Human Cell Culture Made Easy
Blog Feb 23, 2018 | By Anna MacDonald, Science Writer for Technology Networks
Human myocytes stained for MYOG and troponin T
Current disease and drug discovery models are often associated with a number of limitations, calling for a need for improved approaches. We spoke to Dr Mark Kotter, MD PhD, Founder and CEO of Elpis Biomed to learn about the benefits that using human stem cells can bring, and how a novel gene targeting strategy can help researchers optimise the generation of these cells.
Anna MacDonald (AM): What are some of the limitations of current models for research and drug discovery?
Dr Mark Kotter (MK): Currently, most research is conducted on animal models or using cell lines with limited physiological relevance. Biological differences between these models and the actual situation is the largest single reason why drugs fail in late-stage clinical trials (Harrison et al., 2016; Nat. Reviews Drug Discovery).
The use of human cells will help to overcome these limitations.
AM: Why has the use of differentiated stem cells in place of these models so far been slow?
MK: Human stem cells are, in theory, a great source for generating human cells. Their main properties are 1) that they can be expanded infinitely, and 2) that they have the capability of giving rise to all other cell types. In practice, however, the scientific paradigm which has underpinned the use of stem cells is challenging. Traditionally, stem cells are coaxed to "differentiate" step-by-step into the desired target cell. This involves passing through several intermediate (stem cell and progenitor cell) stages. Every stage is determined by a combination of signals in the media. Unfortunately, this process is prone to error at every stage. Some protocols are so difficult that only a few labs are able to master them. As a result, the cultures are not consistent and lack purity. This also negatively affects the scalability of this traditional approach.
MK: Opti-OX is a gene targeting strategy that we developed to efficiently switch on genes in human stem cells. This is important if one wants to harness a novel and highly disruptive way of generating cell types called "direct cellular reprogramming". Cellular reprogramming is similar to running a new program on your computer. Because the genetic program of a cell determines its identity, this results in a complete change of cell type in a single step. However, again, the limitation was that cellular reprogramming was not efficient.
Investigating the reasons as to why cells do not convert, we found that stem cells have an incredibly well established "immune system" that detects reprogramming factors and switches them off, a process called "gene silencing". After several years of hard work and step-wise progress, my academic research team, especially Matthias Pawlowski, a former PhD student who now runs his own lab, came up with Opti-OX. Opti-OX optimises the way reprogramming factors are switched on in human stem cells. This has rendered reprogramming "deterministic", i.e. every Opti-OX cell in the culture will reprogram into e.g. a brain cell, if activated.
Comparison of directed differentiation and reprogramming
AM: What benefits does this technology offer researchers?
MK: Our technology allows researchers working with human cell culture to overcome the long-standing issue of purity, consistency, and scalability. We are now able to generate human brain cells, blood cells, muscle tissue and, in theory, any cell in the human body in a highly reproducible manner. This allows us to put human cells into every lab that is interested in using them and remove the need of any stem cell expertise entirely. It’s human cell culture made easy. Scientists can use these cells for research, drug discovery, toxicology, and for developing cell therapies.
AM: Can you tell us about any future developments planned?
MK: Over the coming months, Elpis will offer more and more different types of human cells. We will start with a range of brain cells (excitatory and inhibitory neurons, motor neurons, sensory neurons, and glia, including astrocytes and oligodendrocytes), muscle tissue and progenitors, and then expand to other tissues. We are already capable of providing cells with specific genetic mutations as disease-in-a-dish models.
In the mid-term, we aim to expand the genetic diversity of our cells to a point where we can provide e.g. human neurons that match an entire population. This will enable researchers to run experiments similar to a clinical trial in a petri dish.
The next step will be to provide more complex models of entire tissues - an area in which we have started to collaborate with a number of partners.
Our biggest ambition, however, is to develop selected cell types for therapy. We have initiated several partnerships that will enable us to fulfil this dream.
Dr Mark Kotter was speaking to Anna MacDonald, Science Writer for Technology Networks.