“Bioactive Glass” Bone Cancer Therapy Kills 99% of Osteosarcoma Cells

Bioactive glass could one day be used as a novel treatment for bone cancer, new research suggests.

In laboratory cell culture tests, researchers found that samples of bioactive glass doped with gallium oxide were able to kill more than 99% of osteosarcoma cells without being cytotoxic to non-cancerous human osteoblasts. The research was published in Biomedical Materials.

What is bioactive glass?

Bioactive glasses are a type of biomaterial routinely used as a filler in dentistry and reconstructive surgery. The glasses are extremely biocompatible, ensuring they won’t be rejected when implanted in the body, and provide a stable surface for bone and bodily tissues to bond with during the healing process. Additionally, the glasses are biodegradable and can even be formulated to release biologically active ions – such as calcium – that help to promote bone growth.

While there has been significant volumes of research looking into the use of these bioactive glasses for bone tissue engineering, comparatively little work has been done on using the materials for the targeted and controlled release of anti-cancer agents that could treat bone cancer.

“Bioactive glass is soluble glass that contains calcium and phosphorous, which are the key building blocks for bone. Bioactive glasses are normally to repair and regenerate bone and enamel,” senior study author Richard Martin, a professor in the College of Engineering and Physical Sciences at Aston University, told Technology Networks. “We wanted to make a material that could not only kill cancer cells but also help regenerate the bone void which is left behind after the surgeon removes the bone tumor.”

Beating bone cancer with bioactive glass

Osteosarcoma is the most common form of primary bone cancer, yet despite advances in chemotherapy and surgical interventions to remove tumors, osteosarcoma survival rates have only risen by 15 percentage points in the past 50 years. Bone cancer patients are also more susceptible to bone fractures and breaks, which can be an additional source of distress and pain.

For their experiments, the Aston University team formulated a novel bioactive glass doped with gallium oxide in different concentrations. These were then ground down into small particles and sieved before use.

“We are using gallium, which is chemically very similar to iron,” Martin said. “Cancers tend to grow much more rapidly and therefore uptake any nutrients/or ions present. So they naturally absorb the toxic gallium.”

Glasses containing 5 mol% gallium oxide were found to reduce the viability of osteosarcoma cells by 99% with no significant reduction seen in healthy control cells, even after 10 days of exposure.

Energy-dispersive X-ray spectroscopy tests also indicated the formation of an amorphous calcium phosphate/hydroxyapatite layer on the surface of the bioactive glass particles following seven days of exposure to simulated body fluids, indicating the beginnings of new bone growth. This additional bone growth is significant as it indicates the potential of these glasses to stimulate bone regeneration after treatment.

“Bone cancer patients tend to have a lower bone density and be more susceptible to fractures. The gallium-doped bioactive glasses will help regenerate bone strengthen the area and hopefully prevent fractures,” Martin said.

In previous studies with 3 mol% gallium oxide bioactive glass, the research team had been able to kill around 40% of osteosarcoma cells, a figure deemed too low to form the basis of future treatments. With these new tests, Martin believes that bioactive glasses of this type could one day lead to effective, localized treatments for bone cancer that also help to regenerate diseased bones.

The team is now hoping to conduct further research with partners and begin trials using gallium-doped bioactive glasses.

“We will be working together with the Royal Orthopaedic Hospital to isolate patient-derived cancer cells and test out the materials against these cells,” Martin said.