RNA therapeutics are transforming modern medicine by directly addressing the biological mechanisms of complex diseases. Lipid nanoparticles (LNPs) have emerged as a leading non-viral delivery platform, accelerating the translation of RNA therapeutics from research to the clinic.
However, expanding applications beyond single-dose vaccines to chronic treatments and extrahepatic targets requires overcoming hurdles such as repeat-dose immunogenicity, ultra-cold storage dependency, and targeted delivery. Addressing these formulation and stability challenges is critical for clinical translation.
This eBook explores key scientific advances in LNP development that are shaping the future of RNA delivery, including repeat dosing, lyophilization, harnessing multi-antigen mRNA, and organ-specific targeting.
Download this eBook to discover:
- The latest strategies for LNP formulation and stability
- How LNPs uniquely enable multi-antigen cancer vaccines
- Key advances enabling organ-specific delivery and antibody targeting
cytiva.com
Lipid
nanoparticles
beyond
vaccines
New frontiers in targeted
and personalized therapeutics2 cytiva.com
Contents
Foreword ..................................................................................................................................3
Chapter 1:
Designing LNPs for repeat dosing: advancing safety and tolerability
beyond vaccines.....................................................................................................................4
Chapter 2:
LNP stability and lyophilization: enabling real-world RNA therapeutics..............10
Chapter 3:
Lipid nanoparticles in personalized cancer vaccines ...............................................15
Chapter 4:
Beyond the liver: advancing LNP delivery to the lung ..............................................21
Chapter 5:
Expanding the horizon: targeted LNPs for extrahepatic delivery ..........................263 cytiva.com
Foreword
We are entering a new era of medicine.
RNA therapeutics are transforming how we approach
disease, not simply by managing symptoms, but by
addressing their underlying biological mechanisms.
By harnessing the body’s own cellular machinery,
these therapies are opening new possibilities for
treating cancer, rare diseases, infectious diseases,
and many other conditions. As our scientific
understanding deepens and technology continues
to advance, RNA-based medicines are becoming an
increasingly versatile platform for developing more
precise, adaptable, and personalized therapies.
Realizing their potential, however, depends on solving
one of the field’s greatest challenges: delivery.
RNA molecules are inherently fragile. Without an
effective delivery system, they are rapidly degraded
before reaching their intended target. Lipid
nanoparticles (LNPs) have emerged as the leading
non-viral delivery platform, protecting RNA, enabling
intracellular delivery, and accelerating the translation
of RNA therapeutics from research to the clinic.
Yet delivery is no longer just about getting RNA
into cells.
As the field expands beyond prophylactic vaccines
toward protein replacement therapies, gene
editing, personalized cancer vaccines, and chronic
diseases requiring repeat administration, the
demands placed on delivery systems are changing.
Future LNP platforms must not only deliver
efficiently, but also demonstrate long-term safety,
repeat-dose tolerability, enhanced stability, scalable
manufacturing, and the ability to precisely target
tissues beyond the liver.
These challenges represent more than technical
hurdles. They define the next phase of innovation in
RNA therapeutics.
Across academia and industry, researchers are
rethinking every aspect of LNP design: engineering
formulations for repeat dosing, developing
alternative stabilizers, improving storage through
lyophilization, and developing targeting strategies
that extend delivery beyond traditional organs.
Together, these advances are expanding the
therapeutic reach of RNA medicines while bringing
them closer to real-world clinical application.
This eBook explores several of the scientific advances
shaping the future of RNA delivery. Drawing on insights
from researchers working across LNP development,
it examines how innovation in formulation, stability,
repeat dosing, and organ-specific targeting is helping
address some of the field’s most important challenges.
While significant challenges remain, the momentum
across the field is unmistakable, moving us closer
to a future where RNA therapeutics can reach
more diseases, more patients, and more healthcare
settings than ever before.4 cytiva.com
Chapter 1:
Designing LNPs for repeat dosing:
advancing safety and tolerability
beyond vaccines
Lipid nanoparticles (LNPs) have transformed
nucleic acid delivery, most visibly through the
success of mRNA vaccines. Yet, as therapeutic
ambitions extend beyond prophylaxis toward
chronic and complex indications, the expectations
placed on delivery systems are changing.
Previously, vaccine design assumptions focused on
single or limited dosing, primarily as prophylactic
measures, relying on a singular prime dose or a few
booster doses. In that context, LNPs were designed
for stability, efficient delivery, and acute tolerability.
Today, the landscape is evolving beyond acute,
one-time interventions and into applications that
require sustained or repeated delivery, including
protein replacement, immune modulation, and
emerging gene editing approaches. When repeated
dosing becomes the foundation of therapeutic
efficacy, a fundamentally different safety paradigm
is introduced. Subtle tolerability liabilities can
compound over time, amplifying concerns around
systemic inflammation, immunogenicity, and
pharmacokinetic variability.
As Nikita Jain, Senior Scientist at Cytiva, explains,
“The strategy must shift from potency-driven
to tolerance-driven. If a therapy is administered
repeatedly or even life-long, tolerability, clearance,
and safety become the primary design criteria.”
For developers, this raises a critical question:
Can LNP platforms maintain safety, efficacy,
and predictable immune compatibility?
Repeated dosing introduces new biological
challenges and potential risks, including immune
activation, organ toxicity, and anti-polyethylene
glycol (PEG) antibody (APA) formation. Each
of these can reduce therapeutic efficacy, alter
biodistribution, or trigger adverse reactions. Among
these risks associated with repeat exposure,
immune recognition remains one of the most
closely scrutinized.
In particular, PEG, used pervasively in creams,
cosmetics,1 food,2 and medicine,3 is also used in
LNP formulations (typically 1%–2% by mole) to
enhance stability and prolong circularization. Its
exposure has been associated with the induction
of APAs in both preclinical and clinical settings,3
raising challenges for dose optimization, regulatory
confidence, and long-term patient management.5 cytiva.com
The PEG challenge:
understanding the
immunological landscape
While PEG has long been the stabilizer of choice
for extending LNP circulation time and preventing
aggregation, recent data highlights a growing
hurdle regarding its immunogenicity.4
Recent data shows:
• Pre-existing APAs have also been detected in
individuals with no prior exposure to PEGylated
drugs, raising additional clinical concerns.5
• Repeated LNP administration can boost these
antibodies, trigger accelerated blood clearance
(ABC), which causes the rapid clearance and
decreased efficacy of therapeutic agents, and
reduce therapeutic payload delivery.6
• Elevated APAs have been linked to enhanced
reactogenicity and altered biodistribution,
which can compromise clinical outcomes,
and it is important to validate this potential
association with larger clinical mRNA health
conference studies.7
These findings underscore a critical reality: for
therapies requiring repeated or chronic dosing,
PEG immunogenicity is a practical barrier to
effective translation.
Environmental
exposure to PEG
Anti-PEG antibodies
develop
Pre-existing antibodies
can reduce effectiveness
of PEGylated drugs
1 2 3
Figure 1. Overview of environmental PEG exposure, anti-PEG antibodies, and therapeutic outcomes6 cytiva.com
Designing LNPs for safer,
repeated dosing
Researchers at Cytiva are using a unique approach
by combining a deep understanding of lipid
chemistry with rigorous preclinical evaluation.
In one of their recent studies on repeat-dose
safety, Nikita and her team evaluated multiple LNP
formulations containing proprietary ionizable lipids
in a nine-dose intramuscular study in mice, with
injections administered every 21 days. The threeweek interval was selected based on precedent
from early clinical-stage cancer vaccine program
studies, providing a practical starting point for
evaluating repeated exposure. The study was
presented at the 2025 mRNA Health Conference in
Berlin, Germany.
This extended regimen enabled evaluation of both
acute and cumulative effects, capturing endpoints
that short-term studies may overlook. Clinical
observations were monitored throughout the
study, alongside comprehensive immunological
assessments. Key readouts included:
• Clinical observations
• Liver enzyme functions
• Inflammatory markers
• Anti-PEG antibody responses/
immune responses
Across all dosing cycles, the results were
encouraging:
• No differences in clinical observations were
seen compared with phosphate-buffered saline
(PBS) controls.
• Measures of liver enzyme, often considered
sensitive indicators of systemic and hepatic
stress, remained stable. This indicated an
absence of hepatotoxicity and suggested
preserved metabolic homeostasis despite
repeated exposure.
• No sustained elevation in inflammatory markers
was detected. Chronic inflammation represents
a central concern for repeat administration
strategies, as even low-grade inflammatory
signaling can contribute to cumulative tissue
stress, immune activation, and patient
discomfort. The absence of sustained
inflammatory responses under extended dosing
supports the favorable tolerability profile of
these formulations.
• Critically, no long-term APAs were observed.
Addressing anti-PEG immunity
– a critical translational barrier
Beyond general tolerability, immune recognition
of nanoparticle components remains a defining
challenge for chronic delivery platforms.
The absence of detectable APAs following
nine-dose LNP administration represents a
meaningful advance. Immune profiling revealed
no long-term adaptive response against PEG
components, with antibody levels remaining
comparable to PBS-treated controls throughout
the study duration.
These findings demonstrate that careful lipid
formulation and dosing strategy alignment can
mitigate immune risk, supporting repeated LNP
administration without compromising safety or7 cytiva.com
tolerability. While continued clinical investigation
remains essential, the ability to maintain
immune tolerance under repeat dosing provides
an important scientific credibility and clinical
relevance for expanding LNP-based therapies into
chronic and high-frequency treatment paradigms.
A crucial insight gained from this study is that a
universal formulation simply doesn’t exist. Even
when using the same lipid components, small
changes in composition can significantly alter how
LNPs behave in the body. As Nikita describes, “We
may use the same components, but by tuning the
composition, we can direct where the LNP goes. If
the goal is liver targeting, the formulation will look
very different from one designed for spleen delivery
or localized expression.”
The formulation tuning is critical because different
applications require different delivery profiles:
• Protein replacement therapies often require
liver targeting.
• Gene editing applications depend on organspecific delivery.
• Vaccines benefit from localized expression and
controlled immune activation.
For vaccines in particular, excessive systemic
exposure can increase the risk of adverse immune
responses. As a result, LNPs are often designed to
remain localized after intramuscular injections, with
controlled drainage to lymph nodes.
This level of precision reinforces a key principle:
LNP design must start with the therapeutic goal,
not the formulation.
Interpreting the implications
of repeated dosing for RNA
therapeutics
Repeated dosing capability opens the door to
chronic, long-term, and multi-dose therapies for
mRNA therapeutics targeting:
• Chronic protein replacement, where consistent
expression is needed over months.
• Gene editing, which may require multiple dosing
to achieve sufficient editing efficiency.
• Immunotherapies, where dosing schedules may
be patient specific.
Moreover, these results reinforce a critical
insight: safety and tolerability must be evaluated
longitudinally under clinically relevant conditions.
Demonstrating preserved tolerability across
repeated administrations, therefore, extends
beyond risk mitigation—it actively expands the
therapeutic design space. Developers gain flexibility
to explore higher cumulative doses, extended
treatment windows, and adaptive dosing schedules
tailored to individual patients’ needs.
At the platform level, these findings reinforce
the importance of integrating lipid chemistry,
immunological insight, and formulation engineering
early in development.
As Nikita explains, “If a therapy needs to be
administered over years, the LNP is no longer just
a delivery system; it effectively becomes part of
the drug.”
By addressing tolerability and immunogenicity at
the design stage, formulation strategies can evolve8 cytiva.com
in parallel with therapeutic ambition rather than
becoming downstream constraints (Table 1).
Short-term focus Long-term focus
High potency High tolerability
Strong endosomal escape Controlled release
Transient cytotoxicity
acceptable
Near-zero cytotoxicity
Rapid effect Sustained, predictable
response
Table 1. Formulation design priorities
This approach allows developers to anticipate
challenges early and reduce risks during clinical
translation.
Preparing for the next evolution
of LNP design
While the favorable safety profile observed in the
study supports continued use of PEG-containing
formulations under optimized conditions, it
also sharpens focus on long-term platform
sustainability. Growing awareness of PEG
immunogenicity, which limits the efficacy of both
commercially available medications and future
therapeutics, is stimulating the development of
alternative stabilization strategies.8
This recognition motivated the development of
Cytiva’s non-PEG stabilizers, a complementary
innovation pathway aimed at expanding formulation
options, enhancing operational flexibility, and
meeting evolving regulatory expectations. Cytiva
offers a library of ionizable lipids and custom
formulation services. By building accessibility and
optionality into LNP chemistry, developers can
proactively adapt to shifting clinical, regulatory,
and commercial landscapes. In this context,
repeat-dosing safety is not an endpoint. Instead,
it becomes a foundation for continued platform
evolution, enabling next-generation LNP systems
capable of supporting increasingly sophisticated
therapeutic designs.
Enabling robust genetic
medicines
The transition from single-dose vaccines to chronic
genetic therapies marks a defining inflection
point for LNP technology. As this unfolds, safety
under repeated exposure emerges as a central
determinant of clinical viability.
Through rigorous preclinical evaluation, Cytiva’s LNP
formulations demonstrate sustained tolerability,
preserved liver function, and the absence of
detectable anti-PEG immune responses under
extended dosing conditions. These results establish
a robust safety foundation while informing ongoing
innovation in non-PEG stabilization strategies.
Together, this integrated approach, combining
lipid chemistry, formulation engineering, and
immunological insight, positions LNP platforms
to support not only today’s mRNA vaccines but
the next generation of genetic medicines. As
therapeutic ambition accelerates, delivery systems
designed for durability, flexibility, and long-term
tolerability will define the pace of clinical translation.9 cytiva.com
References
1. Jang HJ, Shin CY, Kim KB. Safety Evaluation of
polyethylene glycol (PEG) compounds for cosmetic
use. Toxicol Res. 2015;31(2):105–136.
doi: 10.5487/tr.2015.31.2.105
2. Younes M, Aggett P, Aguilar F, et al. Refined exposure
assessment of polyethylene glycol (E 1521) from its use as
a food additive. EFSA J. 2018;16(6):5293.
doi: 10.2903/j.efsa.2018.5293
3. Chen BM, Cheng TL, Roffler SR. Polyethylene glycol
immunogenicity: theoretical, clinical, and practical
aspects of anti-polyethylene glycol antibodies. ACS Nano.
2021;15(9):14022–14048. doi: 10.1021/acsnano.1c05922
4. Fu J, Wu E, Li G, Wang B, Zhan C. Anti-PEG antibodies:
Current situation and countermeasures. Nano Today.
2024;55:102163. doi: 10.1016/j.nantod.2024.102163
5. Fu S, Zhu X, Huang F, Chen X. Anti-PEG antibodies and
their biological impact on PEGylated drugs: Challenges
and strategies for optimization. Pharmaceutics.
2025;17(8):1074. doi: 10.3390/pharmaceutics17081074
6. Gao P. PEGylated lipids in lipid nanoparticle delivery
dynamics and therapeutic innovation. Beilstein J
Nanotechnol. 2025;16:1914–1930.
doi: 10.3762/bjnano.16.133
7. Ju Y, Carreño JM, Simon V, Dawson K, Krammer F, Kent
SJ. Impact of anti-PEG antibodies induced by SARS-CoV-2
mRNA vaccines. Nat Rev Immunol. 2023;23(3):135–136.
doi: 10.1038/s41577-022-00825-x
8. Thi TTH, Pilkington EH, Nguyen DH, Lee JS, Park KD,
Truong NP. The Importance of Poly(ethylene glycol)
alternatives for overcoming PEG immunogenicity in drug
delivery and bioconjugation. Polymers. 2020;12(2):298.
doi: 10.3390/polym12020298
Expert Perspective
While stabilizers account for just a few mole
percent of a formulation, their impact can be
significant. To improve efficacy and overcome
traditional PEG related toxicity, my team is
developing a portfolio of non-PEG stabilizers
with diverse functionalities. For example,
some include end groups that can enable
click-chemistry conjugation of targeting
molecules, opening new possibilities for
antibody-targeted applications.
Nikita Jain
Senior Manager I, Delivery, Cytiva
PhD, Organic Chemistry,
The University of British Columbia10 cytiva.com
Chapter 2:
LNP stability and lyophilization:
enabling real-world RNA
therapeutics
The rapid rise of mRNA–lipid nanoparticle (mRNA–
LNP) technologies has transformed what is possible
in modern science. Yet beyond efficacy and
delivery, a quieter constraint continues to shape
how far these therapies can reach: stability.1,2
LNPs are dynamic assemblies that, while enabling
flexibility and modularity, also raise concerns
about their stability. Additionally, both the lipids
and the encapsulated RNA molecules themselves
are highly sensitive to environmental stress,
particularly temperature fluctuations during
storage and handling.1 As a result, many current
formulations rely on ultra-low temperature storage,
often at -80⁰C.2 However, this requirement
introduces a fundamental challenge: it limits
scalability, complicates distribution, and restricts
access, particularly in settings where cold-chain
infrastructure is not readily available.2
Why LNPs are so sensitive
to storage conditions
The instability of the LNP system is not driven by a
single factor, but by a combination of physical and
chemical processes that occur over time and are
amplified during freeze–thaw cycles.
At the molecular level, degradation pathways affect
both components of the system:
• Lipids can undergo hydrolysis and oxidation.1
• RNA payloads are susceptible to hydrolytic
degradation and structural disruption.1
These changes directly impact critical quality
attributes such as:
• Particle size
• Polydispersity index (PDI)
• Encapsulation efficiency
• RNA integrity
However, one of the most overlooked challenges
arises during freezing and thawing. When LNPs are
frozen, ice crystal formation and phase separation
introduce mechanical stress. Upon thawing, rapid
structural reorganization can further destabilize
this system.311 cytiva.com
Moving beyond ultra-cold
storage
To address these limitations, researchers are
increasingly turning to lyophilization (freeze-drying)
to stabilize LNP formulations. Rather than storing
LNPs as frozen liquids, lyophilization converts
them into a dry, solid form that can be stored at
refrigerated temperatures. However, successful
lyophilization is not simply a matter of removing
water. Without proper formulation design, the
process itself can introduce damage through ice
crystal formation, internal stress during drying,
pH changes, and structural collapse.4 This makes
formulation, particularly excipient selection, central
to success.
Protecting LNP structure
through formulation design
Lyophilization is a critical strategy for improving
the stability, shelf life, and manufacturability of
RNA–LNP therapeutics, but successful freeze-dried
formulations depend heavily on the rational
selection of excipients. Formulation additives play
a crucial role in maintaining nanoparticle structure,
ensuring RNA integrity, and enhancing performance
during freezing, drying, and storage processes.
The role of excipients in stabilizing LNPs
Excipients play a central, multifunctional role
in lyophilized RNA–LNP formulations, acting as
structural and stabilizing enablers rather than
passive ingredients. Disaccharides such as
trehalose and sucrose form an amorphous glass
that replaces water–lipid interactions during
freezing, protecting membranes from ice stress and
maintaining particle integrity after reconstitution.
The polymeric excipients (e.g., hydroxypropyl
β-cyclodextrin, PVP, dextrans) raise the glass
transition temperature to reduce molecular
mobility and improve solid-state stability under less
stringent storage conditions. Moreover, crystallizing
bulking agents like mannitol provide mechanical
strength to the lyophilized cake while buffers such
as histidine or Tris preserve pH and RNA/lipid
integrity during freezing and drying. Additionally,
low levels of nonionic surfactants (e.g., poloxamer
188) mitigate aggregation during processing.3
Together, these excipient systems define the
performance envelope of lyophilized RNA
therapeutics, transforming lyophilization
into a platform strategy that enables robust
manufacturing, distribution, and patient access.3
In a recent lyophilization study, researchers at
Cytiva evaluated how lyophilization strategies
impact LNP stability, specifically whether optimized
buffer systems and excipient combinations
can preserve particle integrity and functional
performance after drying and rehydration.
Researchers identified lyophilization-suitable
buffers that retain the critical quality attributes and
potency of both mRNA and saRNA LNPs following
10 months of storage at 4°C.
Across key metrics, lyophilized formulations
demonstrated:
• Minimal changes in size and PDI
• Stable encapsulation efficiency
• Comparable in vivo efficacy12 cytiva.com
A key observation from this work was that LNP
composition itself remained constant, while
stability outcomes were driven by differences in the
lyophilization buffer system.
“The LNPs perform very similarly to fresh
formulations. Even after months, we didn’t observe
significant changes in efficacy,” notes Hossein Yazdani
Ahmadabadi, Associate Senior Scientist at Cytiva.
From centralized
manufacturing to global access
The implications of improved stability extend far
beyond the lab. During the COVID-19 pandemic,
cold-chain requirements created major logistical
challenges, particularly in regions with limited
infrastructure. Lyophilized LNPs offer a path to
overcome these barriers.
“If you want to ship therapeutics globally without
ultra-cold storage, lyophilization makes a big
difference by enabling distribution using standard
refrigerated conditions,” Hossein adds.
This shift would enable:
• Broader global distribution of LNP medicines
• Improved pandemic preparedness
• Reduced cost and complexity of logistics
Lyophilization is not just a formulation improvement—it reshapes how RNA therapies can be deployed.
Key advantages:
• Eliminates reliance on
ultra-cold storage
• Enables refrigerated
(2°C to 8°C) distribution
• Preserves efficacy over
extended periods
• Simplifies handling in
clinical and field settings
Why lyophilization changes the game
COVID era mRNA cold chain
Manufacturing Ultra-cold
storage -
specialized
freezers
Dry ice
temperature
controlled
transport
Limited
distribution
Limited
stability
Patient
Future lyophilization supply chain
Manufacturing Lyophilization Standard Patient
refrigerated
or room temp
shipping
More
healthcare
settings
Reconstitute
before use13 cytiva.com
Enabling new therapeutic
models
Beyond large-scale distribution, stability plays a critical
role in enabling emerging therapeutic paradigms.
Lyophilization supports on-demand manufacturing
workflows, decentralized production models, and
faster turnaround for patient-specific therapies.
These capabilities are particularly relevant for
personalized cancer vaccines, rare disease
treatments, and small-batch clinical applications.
Remaining challenges and path
to lyophilization adoption
While promising, several challenges remain before
widespread clinical adoption. The Cytiva study data
demonstrate that lyophilization can preserve LNP
integrity and in vivo performance after storage,
but translating this into routine practice requires
addressing several practical and scientific challenges.
Stability is formulation specific, not
universal
In the study, the LNP composition remains
unchanged across samples. But LNPs are diverse,
and formulations are adapted to meet the needs of
different indications. What drives stability during
lyophilization is how well the buffer is matched to
the formulation. Hence, there is no single excipient
system that will translate across all payloads and
LNP chemistries. Importantly, though, there are
numerous levers available to developers to adapt
their lyophilization buffers accordingly.
In practice, this means teams need to treat
stability as a design variable, grounded in a clear
understanding of the target product profile (TPP)
and the real-world circumstances of treatment it
defines, from storage and transport to handling
at the point of care. Until definitive evidence
demonstrates that lyophilization can be developed
independently from formulation as a downstream
fix, it is prudent to align formulation, process, and
stability requirements early, designing with the end
use in mind. This means:
1. Defining stability requirements directly from
the TPP (e.g., temperature excursions, shelf life,
reconstitution constraints)
2. Screening formulations through the entire
workflow, including freeze-drying, testing
excipients and buffer systems for compatibility
3. Assessing particle integrity and potency across
freeze–thaw and drying stresses
4. Considering process implications such as fill
volume, container closure, and cycle scalability
While adding lyophilization introduces additional
steps, timelines, and equipment, this integrated
approach can reduce the risk of late-stage
surprises, especially for programs moving quickly
from preclinical to clinical phases.
Scaling the process introduces new
variables
Lyophilization performs well at a small scale, but
consistency becomes more difficult as batch
sizes increase.
Key factors include:
• Freezing rate and uniformity across
larger volumes14 cytiva.com
• Control of cake structure and residual moisture
• Reproducibility during reconstitution
A small shift in these parameters can affect particle
size, PDI, and ultimately performance.
Analytical and regulatory expectations
remain high
Transitioning from liquid to lyophilized formats
requires clear evidence of compatibility and
effectiveness. Developers need to demonstrate
consistent particle size, distribution, maintained
encapsulation efficiency, and preserved biological
activity. The findings from the Cytiva study are
encouraging, but building a robust dataset will be
essential to support regulatory submissions.
Application across modalities is still
evolving
The study data provide a strong foundation, but
broader validation is still needed to answer the
open questions:
• How different payloads respond to the same
buffer strategies
• Whether similar outcomes can be achieved
across delivery routes
• How complex or sensitive constructs behave
during drying and rehydration
Looking ahead
Lyophilization changes how LNPs can be stored,
handled, and deployed. However, its full impact
depends on how early it is integrated into the
development strategy. The opportunity is clear.
The next step is bringing formulation, process, and
application requirements together to make stability
a built-in feature.
References
1. Schoenmaker L, Witzigmann D, Kulkarni JA, et al.
mRNA-lipid nanoparticle COVID-19 vaccines: structure
and stability. Int J Pharm. 2021;601:120586.
doi: 10.1016/j.ijpharm.2021.120586
2. Crommelin DJA, Anchordoquy TJ, Volkin DB, Jiskoot W,
Mastrobattista E. Addressing the cold reality of mRNA
vaccine stability. J Pharm Sci. 2021;110(3):997–1001.
doi: 10.1016/j.xphs.2020.12.006
3. Khan MDFH, Baudin F, Perumal AS, Kamen AA. Freezedrying of mRNA-LNPs vaccines: A review. Vaccines.
2025;13(8):853. doi: 10.3390/vaccines13080853
4. Ruppl A, Hutanu A, Köll-Weber M, Allmendinger A.
Freezing-induced stress in mRNA-lipid nanoparticles
during lyophilization: mechanistic insights from process
and formulation studies. Pharm Res. 2026;43:877–889.
doi: 10.1007/s11095-026-04039-x
Expert Perspective
LNP lyophilization is particularly challenging
because water plays a critical role in LNP
structure, and no two formulations are
exactly alike. Through this work, we’ve gained
valuable process insights, and a strong
understanding of the key variables that our
services team can apply to help customers
develop lyophilization strategies tailored to
their formulations.
Hossein Yazdani
Formulation Scientist II, Cytiva
PhD, Chemistry, The University of British Columbia15 cytiva.com
Chapter 3:
Lipid nanoparticles in
personalized cancer vaccines
Cancer is not a single disease but rather a
dynamic, evolving system of mutations. Even
tumors originating in the same tissue can vary
dramatically between patients and, at times, within
the same tumor. This heterogeneity has driven
growing interest in personalized cancer vaccines
(PCVs), an emerging immunotherapy approach
designed to train the immune system to recognize
the unique molecular fingerprints of an individual
patient’s tumor.1
Rather than targeting a universal tumor antigen,
personalized vaccines rely on neoantigens, which
are mutated proteins that arise from tumor-specific
genetic changes. Advances in genome sequencing
and computational prediction allow researchers
to identify these neoantigens by comparing
tumor DNA and RNA with healthy tissue from the
same patient.2
Once identified, these neoantigens can be encoded
with mRNA sequences and delivered as a vaccine
capable of stimulating anti-tumor immune responses.
However, the success of this strategy depends on
a critical enabling technology: efficient delivery of
complex RNA constructs into immune cells.
Why delivery matters in cancer
vaccines
mRNA molecules are inherently fragile and cannot
easily enter cells on their own. Without protection,
they degrade rapidly in biological environments.
Lipid nanoparticles (LNPs) solve this challenge
by encapsulating mRNA and facilitating cellular
uptake. Once inside the target cells, the RNA
can be translated into antigen proteins that are
presented to the immune system, triggering
immune activation.
This delivery capability has become central to the
rapid progress of mRNA-based therapeutics and
vaccines. Moreover, LNP delivery technologies
have matured significantly in recent years, with
advances in formulation design improving not only
delivery but also safety, tolerability, and stability.
These improvements have enabled the transition
from simple RNA payloads to more complex
therapeutic constructs.
As a result, researchers can now explore
applications such as multi-antigen personalized
cancer vaccines, where both delivery performance
and formulation robustness are critical to success.16 cytiva.com
Multi-antigen vaccine for
complex tumors
Tumors rarely rely on a single mutation to drive
progression. Instead, they often harbor numerous
genetic alterations that drive tumor growth and
immune evasion.
For this reason, many personalized vaccine
strategies encode multiple tumor antigens within a
single mRNA construct.3
In a recent study at Cytiva, researchers evaluated
multi-epitope mRNA constructs encoding
combinations of melanoma-associated antigens
designed to stimulate broad anti-tumor immune
responses in a melanoma model.
Why LNPs uniquely enable multi-antigen
vaccines
Personalized cancer vaccines often encode multiple neoantigens simultaneously. Delivering such
complex payloads would be extremely challenging with many traditional vaccine platforms.
Lipid nanoparticles enable this strategy by:
• Protecting fragile RNA molecules from degradation
• Facilitating efficient intracellular delivery
• Enabling flexible mRNA design, where multiple antigens can be encoded and quickly reconfigured
without re-engineering the delivery platform
Tumor
biopsy
Mutation
identification Neoantigen
prediction
Nucleic
acids
Multiple epitopes
Delivery
5’ neo1 neo2 neo9 neo1017 cytiva.com
These vaccines aimed to activate both:
• CD8+ cytotoxic T cells, which directly kill
tumor cells
• CD4+ helper T cells, which support and sustain
immune responses4
Activating multiple immune pathways simultaneously
may help overcome tumor heterogeneity and reduce
the risk of immune escape.
Formulation choices shape
delivery performance
While mRNA sequence design is critical, the LNP
formulation itself plays an equally important role in
determining therapeutic performance.
Key parameters that influence LNP
behavior include:
• The choice of ionizable lipid
• The ratio of lipid components
• Particle size and structural organization
• Encapsulation efficiency and stability
According to Jay Paquette, a scientist at
Cytiva who worked on the melanoma model,
formulation differences can significantly influence
biological outcomes.
“Picking the right ionizable lipid matters a great
deal,” Jay explains. “Some ionizable lipids work
extremely well in certain models, while others don’t
work at all. Even the ratios of those components
can change how the nanoparticle performs. That’s
why it’s important to test them across different
systems before drawing conclusions.”
This sensitivity means that formulation
development often requires extensive screening
and empirical testing.
Applying a validated LNP
platform in a melanoma model
Rather than designing a completely new
nanoparticle formulation for the melanoma
study, the research team selected a lead LNP
platform that had previously demonstrated strong
performance across multiple in vivo models.
This approach allowed the investigators to focus
on evaluating the multi-antigen mRNA constructs
themselves while relying on a delivery system that
had already been characterized.
“We had already screened several LNP formulations
in different applications,” Jay explains.
“This particular formulation had shown strong
performance across models, so we used it as the
starting point for this melanoma study.”
The mRNA construct encoding melanoma antigens
were encapsulated within lipid nanoparticles and
characterized using standard metrics, including:
• particle size
• polydispersity index (PDI)
• encapsulation efficiency
The resulting formulations were then evaluated in a
tumor-bearing mouse model of melanoma.18 cytiva.com
Early signals of therapeutic
potential
The vaccine candidates demonstrated promising
activity in vivo. Several multi-antigen constructs
produced measurable anti-tumor responses,
resulting in slower tumor progression and improved
survival compared with untreated controls.
Although the work represents an early-stage proof
of concept, it illustrated how LNP-mediated delivery
can support complex mRNA vaccine strategies
targeting multiple tumor antigens simultaneously.
Jay emphasizes that these findings represent an
important but preliminary step.
“It’s important to remember that this is still a
mouse melanoma model,” he says. “What we’re
demonstrating is that this approach can generate
an immune response and influence tumor growth.
Translating that into therapies will require a lot
more work.”
Translational challenges remain
Despite encouraging progress, several scientific
and logistical challenges must be addressed before
personalized cancer vaccines can become routine
clinical therapies.
Neoantigen identification: the real
bottleneck in personalization
Identifying the most immunogenic tumor
mutations that will generate a meaningful immune
response remains a complex task. Modern
sequencing approaches can reveal dozens to
hundreds of candidate neoantigens from a single
tumor sample. However, only a small subset
of these is likely to be presented effectively by
antigen-presenting cells and recognized by T cells.5
“Finding the right epitopes is one of the hardest
parts,” Jay explains. “You may identify dozens of
mutations, but figuring out which ones will actually
trigger a strong immune response is far from
straightforward.”
One common strategy is to prioritize neoantigens
based on factors such as expression level, binding
affinity to major histocompatibility complex
(MHC) molecules, and predicted immunogenicity.
However, these parameters do not always translate
directly into clinical response.
“Just because an epitope is highly expressed
doesn’t mean it will generate a strong immune
response,” Jay notes. “If it were that simple,
the immune system would have already cleared
the tumor.”
This uncertainty introduces an element of empirical
decision making into vaccine design. In some
cases, researchers select a diverse set of epitopes,
including highly expressed and moderately
expressed candidates, to increase the likelihood
of eliciting a productive immune response. At the
same time, there is a need to carefully balance
specificity and safety.
“You also have to consider how similar these
epitopes are to normal proteins,” Jay explains. “If
you select something too close to what’s already
present in healthy tissue, you risk triggering an
unintended autoimmune response.”19 cytiva.com
As a result, neoantigen selection represents a
multidimensional challenge requiring integration
of genomic data, immunological insight, and
predictive modeling. Increasingly, computational
approaches and machine learning tools are being
explored to improve the accuracy and speed of
this process, particularly as personalized therapies
move toward clinical implementation.
Manufacturing speed
Personalized vaccines require a rapid turnaround
between tumor sequencing and therapeutic
administration.
“You’re essentially developing a new drug for a
single patient,” Jay says. “That means identifying
the epitopes, producing the mRNA sequence,
formulating it into nanoparticles, and delivering it
quickly enough to make a clinical difference.”
Automation and scalable RNA manufacturing
platforms will be essential to support this workflow.6
Combination immunotherapy
strategies
Many researchers expect personalized cancer
vaccines to work best when combined with other
immunotherapies.
Immune checkpoint inhibitors, which prevent tumors
from suppressing immune responses, have already
demonstrated a transformative impact in oncology.7
Combining these therapies with personalized
vaccines may produce stronger, more durable
antitumor responses.
“A cancer vaccine may alone not be the full
answer,” Jay explains. “But when combined with
checkpoint inhibitors or other immunotherapies,
there’s a real potential to create a much stronger
therapeutic effect.”
Towards individualized cancer
treatment
As genomic sequencing, RNA synthesis, and
delivery technologies continue to evolve,
personalized cancer vaccines are emerging as
a promising addition to the oncology treatment
landscape. These approaches are often framed in
terms of individualization, tailoring therapies to the
unique mutation profile of each patient’s tumor.
However, their potential impact extends beyond
personalization alone.
One of the most important advantages of
immuno-oncology approaches lies in their ability
to address residual disease, recurrence, and
metastasis—challenges that remain difficult to
manage with conventional therapies. Surgeries
and radiation can effectively remove or reduce
primary tumors, but they do not always eliminate
micrometastatic disease, where a small population
of persisting cancer cells can eventually relapse
and spread from the primary tumor to another
part of the body. Similarly, systemic therapies may
reduce tumor burden but often lack the specificity
or durability needed for long-term control.20 cytiva.com
Personalized cancer vaccines offer a different
mechanism. By training the immune system to
recognize tumor-specific antigens, they have the
potential to establish ongoing immune surveillance,
enabling the body to detect and eliminate cancer
cells that re-emerge over time.
“Personalized cancer vaccines could eventually
become part of follow-up treatment,” Jay says.
“After removing the primary tumor, a vaccine could
help the immune system eliminate remaining
cancer cells and prevent metastasis.”
In this context, individualized vaccine design is
not the endpoint; it is the enabler of a broader
therapeutic goal: durable, system-wide protection
against recurrence.
Realizing this vision will require advances across
multiple domains, including neoantigen selection,
manufacturing speed, and clinical integration. Yet the
convergence of these capabilities suggests a future
in which cancer treatment extends beyond tumor
removal toward long-term disease management
driven by the patient’s own immune system.
References
1. Lu L, Lu X, Luo W. Personalized Cancer vaccines:
Current advances and emerging horizons. Vaccines.
2025;13(12):1231. doi: 10.3390/vaccines13121231
2. Sahin U, Derhovanessian E, Miller M, et al. Personalized
RNA mutanome vaccines mobilize poly-specific
therapeutic immunity against cancer. Nature.
2017;547:222–226. doi: 10.1038/nature23003
3. Fennemann FL, de Vries IJM, Figdor CG, Verdoes M.
Attacking tumors from all sides: Personalized multiplex
vaccines to tackle intratumor heterogeneity. Front
Immunol. 2019;10:824. doi: 10.3389/fimmu.2019.00824
4. Ostroumov D, Fekete-Drimusz N, Saborowski M, Kühnel
F, Woller N. CD4 and CD8 T lymphocyte interplay in
controlling tumor growth. Cell Mol Life Sci. 2018;75:689–
713. doi: 10.1007/s00018-017-2686-7
5. Zhang Y, Chen TT, Li X, et al. Advances and challenges
in neoantigen prediction for cancer immunotherapy.
Front Immunol. 2025;16:1617654. doi: 10.3389/
fimmu.2025.1617654
6. Magoola M, Niazi SK. Current progress and future
perspectives of RNA-Based cancer vaccines: A 2025
update. Cancers. 2025;17(11):1882 doi: 10.3390/
cancers17111882
7. Ribas A, Wolchok JD. Cancer immunotherapy using
checkpoint blockade. Science. 2018;359(6382):1350–
1355. doi: 10.1126/science.aar4060
Expert Perspective
Manufacturing personalized cancer vaccines at small scale remains a significant challenge. The NxGen™
scale ready cartridge provides a gamma-irradiated, animal origin-free, fully traceable solution that helps
researchers transition from process development to small-scale clinical studies using the NanoAssemblr
Ignite™ system.
Jay Paquette
Senior Manager, Nucleic Acids and Nanomedicine, Cytiva
PhD, Psychology: Brain, Behaviour and Cognitive Science, Queen’s University21 cytiva.com
Chapter 4:
Beyond the liver: advancing LNP
delivery to the lung
In previous chapters, we explored how advances in
lipid nanoparticle (LNP) formulation are enhancing
efficiency, manufacturability, and their application
in personalized cancer vaccines. Yet, formulation
optimization alone cannot unlock the full potential
of RNA therapeutics. The next major challenge lies
in directing those systems beyond their natural
destination—the liver.1
Today, most lipid nanoparticle systems used to
deliver RNA accumulate primarily in the liver
following systemic administration. This biological
bias has enabled important therapeutic advances,
but it also limits the range of diseases that RNA
medicines can target. Researchers across academia
and industry are now working to overcome this
constraint. Achieving extrahepatic delivery to other
organs has become one of the most important
frontiers in RNA medicine. Among the emerging
targets, the lung represents both a compelling
opportunity and a formidable scientific challenge.
Why lung delivery presents a
unique challenge
Pulmonary diseases represent a major unmet
medical need. Conditions such as cystic fibrosis,
chronic obstructive pulmonary disease (COPD),
and rare genetic lung disorders could potentially
benefit from RNA therapies capable of restoring or
modifying protein expression directly within airway
cells. However, the lung is not an easy target for
nanoparticle delivery.
Unlike hepatocytes, pulmonary cells are protected
by multiple biological barriers, including mucus
layers, airway branching structures, and rapid
clearance mechanisms. Inhaled particles must
navigate these barriers before reaching epithelial
cells capable of expressing the therapeutic RNA.2
“Pulmonary cells are completely different
from other cells in the body”, explains Cytiva
scientist Noorjahan Aibani, whose work focuses
on developing LNP systems for pulmonary RNA
delivery. “That means the design rules we use
for liver delivery cannot simply be applied to
lung tissue.”
Traditional intravenous administration also
performs poorly for lung targeting. As a result,
researchers are exploring inhalation-based delivery
methods, including nebulization, that can deposit
nanoparticles directly into the respiratory tract.
However, this strategy faces formulation challenges.
Only a small fraction of inhaled particles ultimately
deposit in the lower respiratory tract, meaning the
delivery system must achieve strong transfection
efficiency even at relatively low effective doses.22 cytiva.com
Key barriers to pulmonary RNA
delivery
Pulmonary tissue presents several biological and
engineering challenges for RNA delivery systems:
• Airway mucus layers that trap nanoparticles
• Rapid mucociliary clearance mechanism
• Complex branching airway architecture
• Low deposition efficiency during
inhalation delivery
• Mechanical stress during aerosolization
• Distinct pulmonary cell biology compared with
hepatocytes
Overcoming these barriers requires nanoparticle
composition specifically optimized for
pulmonary tissues.
Engineering LNPs for
pulmonary delivery
LNPs typically contain four core components:
• An ionizable lipid that facilitates RNA
encapsulation and endosomal escape
• Cholesterol that stabilizes the lipid layer
• Helper phospholipids that support
particle structure
• Surface modifying lipids that regulate particle
size, colloidal stability, and biological interaction
Adjusting the relative proportions of these
components can significantly influence
biodistribution, cellular uptake, and intracellular
RNA release.3
To better understand how nanoparticle composition
influences pulmonary delivery, researchers recently
evaluated a panel of LNP formulations designed
to deliver mRNA to the lung through nebulization.
In the study, multiple formulations were screened
to identify combinations capable of producing
measurable expression in lung tissue following
inhalation delivery.
One observation was particularly notable: several
formulations containing lower relative amounts of
structural helper lipids produced higher reporter
gene expression in lung tissue, a result that initially
appeared counterintuitive.
Conventional lipid nanoparticle designs usually rely
on helper lipids to stabilize their structure.
However, the specific mechanisms involved
in the pulmonary environment are still under
investigation. Several hypotheses can explain this
behavior. One possibility is that a reduced quantity
of structural lipids may increase the flexibility of
the nanoparticle membranes, enhancing their
interaction with pulmonary cell membranes and
aiding in endosomal escape after cellular uptake.
These findings reinforce a broader theme emerging
across RNA delivery research: each organ requires
its own formulation design strategy.23 cytiva.com
Ensuring nanoparticle stability
during nebulization
Pulmonary delivery also introduces a mechanical
challenge that does not occur with conventional
intravenous administration: aerosolization.
During nebulization, nanoparticles experience
shear stress and repeated air–liquid interface
exposure. These forces can destabilize lipid
structure or reduce RNA encapsulation efficiency.
For inhaled RNA therapeutics to be viable, LNPs
must retain their physiological integrity during
this process. To address this concern, researchers
evaluated nanoparticle size, encapsulation
efficiency, and other critical quality attributes
before and after nebulization.
Encouragingly, the tested LNPs maintained
structural integrity under aerosolization conditions.
“Our work showed that the particles remained
stable after nebulization,” Noorjahan notes. “That is
essential if pulmonary RNA delivery is going to work
in practice.”
Maintaining stability during aerosolization is a key
prerequisite for translating inhaled RNA therapies
into clinical applications.
Building a platform for
pulmonary RNA therapeutics
Although pulmonary delivery research is often
motivated by specific diseases such as cystic
fibrosis, the implications extend well beyond a
single indication.
Pulmonary delivery
Inhalation can access lung tissue
in ways intravenous administration
cannot.
However, during nebulization, nanoparticles
experience shear stress and repeated air–liquid
interface exposure. These forces can destabilize
lipid structure or reduce RNA encapsulation
efficiency. What if LNPs could be engineered to
overcome this challenge?24 cytiva.com
“What we are developing is not limited to one
disease,” Noorjahan explains. “This type of delivery
platform could support long-term expression
studies, gene editing approaches, and other
advanced RNA therapies in the lung.”
Efficient pulmonary delivery could enable:
• Gene replacement strategies for inherited
lung disease
• Localized immunotherapies for
respiratory cancers
• CRISPR-based gene editing targeting airway
epithelial cells
Given the limited success of previous therapeutic
approaches for some pulmonary genetic disorders,
improved RNA delivery systems could represent a
significant breakthrough.
Designing RNA therapies for
real-world accessibility
Scientific performance is only one aspect
of successful RNA therapeutics. Practical
considerations such as storage stability,
manufacturing scalability, and patient accessibility
also play critical roles. Many current LNP
therapeutics require ultra-cold storage conditions,
sometimes as low as -80⁰C. While manageable for
controlled vaccine distribution, such requirements
could complicate long-term treatment strategies
for chronic respiratory diseases.
Researchers are therefore exploring alternative
formats such as lyophilized dry-powder inhalation
systems. These systems could potentially enable
RNA medicines to be delivered using inhaler devices
similar to those already used for asthma treatments.
“Accessibility is an important consideration,”
Noorjahan says. “It is not only about scaling up
manufacturing. In some cases, it is also about
producing smaller batches that can reach individual
patients.”
This perspective reflects a broader shift towards
flexible manufacturing models that can support
both large-scale production and personalized
medicine applications.
A rapidly evolving field beyond
vaccines
Momentum in RNA therapeutics continues to
grow across multiple areas of medicine. Research
programs that began with vaccine development
are now expanding into cancer immunotherapy,
gene editing technologies, and treatments for rare
genetic diseases.
As these applications emerge, delivery remains
the central challenge. The ability to direct RNA
therapeutics to specific tissues will ultimately
determine which diseases these technologies
can address.
Pulmonary delivery research provides a clear
example of how the field is beginning to tackle this
challenge. By combining formulation engineering
with inhalation-based administration strategies,
researchers are starting to move RNA medicines
beyond their natural liver tropism into previously
difficult-to-reach organs.25 cytiva.com
Expanding the reach of RNA
medicine
The ability to deliver RNA beyond the liver
represents one of the most important milestones in
the evolution of RNA therapeutics.
Advances in nanoparticle formulation, aerosol
delivery technologies, and translational research are
beginning to expand the reach of RNA medicines.
What once appeared to be a fundamental limitation
of the lipid nanoparticle system is now becoming an
active area of innovation.
Pulmonary-targeted LNPs illustrate how this
progress is unfolding. By adapting nanoparticle
design to the unique biology of airway tissues
and ensuring that formulations remain stable
during inhalation delivery, researchers are
beginning to unlock new possibilities for treating
respiratory diseases.
While significant scientific and translational
challenges remain, continued advances in delivery
technology may soon allow RNA therapeutics
to reach organs that were once considered
inaccessible. For pulmonary diseases such as
cystic fibrosis and COPD, these innovations
could ultimately open the door to entirely new
therapeutic approaches.
References
1. Cullis PR, Hope MJ. Lipid nanoparticle systems for
enabling gene therapies. Mol Ther. 2017;25(7):1467–1475.
doi: 10.1016/j.ymthe.2017.03.013
2. Paranjpe M, Müller-Goymann CC. Nanoparticle-mediated
pulmonary drug delivery: A review. Int J Mol Sci.
2014;15(4):5852–5873. doi: 10.3390/ijms15045852
3. Hou X, Zaks T, Langer R, Dong Y. Lipid nanoparticles for
mRNA delivery. Nat Rev Mater. 2021;6:1078–1094. doi:
10.1038/s41578-021-00358-0
Expert Perspective
Because this study involved screening
dozens of formulations, consistency was
critical. The NanoAssemblr Ignite™ system
allowed us to produce formulations quickly
and reproducibly, making it easier to
distinguish chemistry-driven effects from
formulation variability. The resulting volumes
also aligned well with the needs of our
in vivo studies.
Noorjahan Aibani
Scientist II, Delivery, Cytiva
PhD, Pharmaceutical Sciences, Ulster University26 cytiva.com
Chapter 5:
Expanding the horizon: targeted
LNPs for extrahepatic delivery
As discussed in the previous chapter, advancing
extrahepatic RNA delivery using lipid nanoparticles
(LNPs) marks a pivotal step in overcoming the
liver’s intrinsic role as a biological “sink”. While the
lung presents a distinct and accessible target via
inhalation, the true inflection point lies beyond
localized delivery. The field is now converging
on the more complex challenge of systemic
administration, where precise modulation of LNP
biodistribution is essential to unlock efficient
targeted delivery to distal organs. Achieving
this level of control will define the next era of
RNA therapeutics, requiring deeper integration
of particle engineering, biological insight, and
translational strategy.
The spleen as a strategic target
for next-generation therapies
In vivo CAR T therapy is emerging as a defining
application of LNP technology, enabling direct
genetic modification of T cells to recognize and
eliminate cancer.
Conventional CAR T approaches rely on complex
ex vivo workflows where patient cells are
harvested, modified in labs, and reinfused weeks
later, introducing significant time, cost, and
manufacturing constraints.1
LNPs carrying messenger RNA (mRNA) offer a
streamlined alternative by genetically modifying T
cells directly within the patient’s body. This allows
for temporary expression of chimeric antigen
receptors (CARs), enabling CAR T therapy to be
administered as an “off-the-shelf” injection. This
approach has the potential to reduce logistical
and manufacturing complexity, treatment time,
and cost.1
However, making in vivo CAR-T therapy clinically
viable depends on overcoming a major biological
challenge: directing LNPs away from the liver and
toward immune-relevant organs such as the spleen.
As a primary lymphoid organ enriched with T cells
and antigen-presenting cells, the spleen offers a
uniquely permissive environment for immune-cell
targeting and activation.
Achieving this level of organ-specific targeting is
an important step towards expanding therapeutic
applications of RNA–LNP technology.
Achieving cell-specific targeting
Even if a delivery system successfully reaches the
intended organ, such as the spleen, an additional
challenge remains: targeting specific cell populations
within a heterogeneous tissue environment.27 cytiva.com
Off-target delivery at the cellular level
introduces significant risk, including unintended
gene disruption, aberrant cell activation, or
immune-mediated toxicity, causing immune
attacks on healthy cells.2 As a result, precision at
the cellular scale is not simply optimization, it is
also a prerequisite for clinical viability.
To improve cellular specificity, delivery systems
often incorporate ligands such as antibodies or
peptides. However, these approaches introduce
additional design complexity requiring careful
optimization.3 Ligand density, for example, must
be finely tuned, as insufficient density can reduce
binding efficiency while excessive functionalization
may cause aggregation or rapid immune clearance.
Ultimately, for in vivo cell therapy to move beyond
experimental trials and into routine medicine,
researchers must prove that they can successfully
deliver payloads to the correct cell, in the correct
organ, with high precision and reproducibility.
Enabling spleen tropism with
advanced LNP formulations
To overcome the inherent “liver sink” that often
limits systemic RNA therapies, Cytiva is developing
an advanced LNP-based delivery platform designed
to enable more selective, extrahepatic distribution.
To evaluate its potential for extrahepatic delivery,
proprietary LNP–mRNA compositions were tested
in mouse models.4 The results showed high levels of
mRNA translation across multiple organs, such as
the lungs, kidneys, and heart, confirming efficient
mRNA delivery and expression.
This ability to bypass the hepatic “sink” represents
a pivotal step in expanding the reach of RNA–LNP
technology.
The most notable observation, however, was the
platform’s distinct spleen tropism: The lead LNP
formulation achieved a 34-fold increase in trafficking
to the spleen relative to the liver (Figure 1).
By leveraging the spleen’s role as a primary hub
for immune cell activity, this approach unlocks
new opportunities for immune-focused in vivo
delivery strategies.
40
30
20
10
0
PBS LNP 1 LNP 8 LNP 9
Spleen/liver ratio (from avg. total flux)
Figure 1. Cytiva’s LNPs enabled 34-fold higher
spleen expression compared to the liver.
Refining specificity: from organ to cell
Reaching the correct organ is only half the battle;
the payload must then reach the specific cells
capable of mounting an immune response.
Analysis of spleens from mice injected with LNPs
revealed targeting across a range of cell types.4
Specifically, macrophages and natural killer cells
showed higher transfection rates than T cells, B
cells, and dendritic cells. This represents a promising
avenue for chimeric antigen receptor macrophage
(CAR-M) therapy and next-generation vaccines.28 cytiva.com
To enhance cell-specific activity, CD8+ targeting
moieties were conjugated to LNPs. When tested
in a humanized mouse model, these targeted
LNPs (tLNPs) successfully directed mRNA to
the target T-cell populations, as evidenced by
significantly higher transgene expression in CD8+
T-cell populations than in CD4+ T-cell populations
(Figure 2).
Not to be overlooked, advanced analytics developed
by Cytiva’s BioPharma Services team were crucial
in measuring the state of conjugation of targeting
moieties, providing a readout to fine-tune the
conjugation reaction. This combination of Cytiva’s
advanced LNP formulations, ligand targeting, and
analytical confirmation has enabled immune-cell
programming in vivo—an important capability for
translating targeted RNA therapies into scalable
and clinically practical treatment platforms.
Demonstrating therapeutic efficacy
A key test of the platform was its ability to generate
functional in vivo CAR-T cells capable of eliminating
cancer. Mice with humanized tumors received tLNPs
containing CAR mRNA, and the growth or regression
of their cancer cells was tracked in real time.
The results demonstrated:
• Regression of cancer cells in treated mice
• Dose-dependent effects
• No observed adverse effects, suggesting the
formulations were well tolerated
Figure 2. Key insights into Cytiva’s innovation in LNP development
Conventional LNP
Cytiva LNP
Intravenous
administration
Intravenous
administration
Natural accumulation
in liver
34x trafficking
to spleen over liver
Uptake in liver cells
Ligand conjugation enabling
cell-specific targeting29 cytiva.com
The selective and dose-dependent killing of tumor
cells illustrates the potential of the tLNP platform
for transient in vivo CAR-T cell therapy.
A comprehensive platform for
extrahepatic delivery
As LNP formulations incorporate targeting
moieties, advanced analytical methods are
required to:
• Characterize surface conjugation
• Detect unconjugated particles or residual
targeting moieties
• Assess targeting specificity and activity
Cytiva’s BioPharma Services bring together
formulation and analytics into an end-to-end
unified workflow, supported by NanoAssemblr™
systems, to enable the design, production, and
characterization of complex LNP constructs.
Central to this platform is an extensive library of
ionizable lipids, including those explored above,
distinguished by unique linker structures that
offer enhanced biodegradability while maintaining
flexibility in design and application. This portfolio
is further supported by specialized non-PEG
stabilizers, providing a complete toolkit for
researchers looking to optimize delivery, stability,
and targeting performance for in vivo cell therapy.
Broadening the scope of RNA
therapeutics
While the potential of RNA therapeutics is vast,
clinical progress has long been constrained
by challenges of delivery beyond the liver. The
demonstration of successful targeting of the spleen
via LNPs represents a substantial leap toward
piercing that horizon, demonstrating that the liver
“sink” is no longer an insurmountable barrier.
By ensuring the payload reaches the “right postal
code” through the LNP formulation and the “right
address” through targeting moieties, this platform
paves the way for therapies that avoid the costs
and complexities of traditional ex vivo processes.
Ultimately, this core technology provides a blueprint
to potentially enable RNA delivery to a wide array
of non-liver targets. As active targeting strategies
continue to mature, the goal of making the next
generation of genomic medicine accessible to every
patient is moving steadily within reach.
References
1. Pinto E, Lione L, Compagnone M, et al. From ex vivo
to in vivo chimeric antigen T cells manufacturing: new
horizons for CAR T-cell based therapy. J Transl Med.
2025;23:10. doi: 10.1186/s12967-024-06052-3
2. Kalter N, Fuster-García C, Silva A, et al. Off-target effects
in CRISPR-Cas genome editing for human therapeutics:
Progress and challenges. Mol Ther Nucleic Acids.
2025;36(3):102636. doi: 10.1016/j.omtn.2025.102636
3. Lin X, Xiang H, Wu J, et al. The evolution of lipid
nanoparticles: Paving the way for next-generation nucleic
acid medicines. Asian J Pharm Sci. 2026;21(1):101121.
doi: 10.1016/j.ajps.2026.101121
4. Golla K, Sams S, Yazdani H. Extrahepatic delivery of
mRNA LNP to spleen: Towards in vivo CAR therapeutics.
Cytotherapy. 2026;28(5):102591.
doi: 10.1016/j.jcyt.2026.10259130 cytiva.com
Expert Perspective
Targeted LNPs have the potential to transform the future of RNA medicines by enabling precise delivery
to relevant tissues and cell types. Realizing this potential involves navigating significant scientific and
technical complexity, along with the establishment of appropriate CMC frameworks. Compared with
conventional LNPs, targeted LNPs require more sophisticated analytical strategies to comprehensively
characterize their attributes and understand how those attributes influence biological performance. By
leveraging our extensive portfolio of ionizable lipids and stabilizers, robust analytical capabilities, and close
collaboration across our chemistry, formulation, bioassay, process development, and analytical teams, and
through strong partnerships with our collaborators, we generate the insights needed to accelerate the
development and success of our partner programs. We ultimately believe this close collaboration is key to
pushing the boundaries of targeted delivery and advancing programs toward clinical readiness.
Anitha Thomas
Director, R&D, Cytiva
PhD, Chemistry, Interdisciplinary Chemistry & Biology, Indian Institute of Science (IISc)31 cytiva.com
Featured resources
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About This eBook
This eBook was developed through interviews and
contributions from Cytiva subject matter experts
and written by the editorial team at Cytiva.
Written by
Reshma Kapatrala
Marketing Writer, Cytiva
Subject Matter Experts
Nikita Jain, PhD
Senior Manager I, Delivery, Cytiva
Hossein Yazdani Ahmadabadi, PhD
Formulation Scientist II, Cytiva
Jay Paquette, PhD
Senior Manager, Nucleic Acids and Nanomedicine, Cytiva
Noorjahan Aibani, PhD
Scientist II, Delivery, Cytiva
Anitha Thomas
Director, R&D, Cytiva
Shell Ip, PhD
Client Learning and Scientific Content, Nanomedicine, Cytiva