Hot on the trail of bone cancer recurrence

A new composite scaffold material promotes bone repair while preventing the recurrence of osteosarcoma, a rare but aggressive form of bone cancer that occurs in children and young adults. The new scaffold has the potential to improve recovery from the disease. 

The repair of bone defects caused by osteosarcoma, as well as defects caused by trauma or infection, can be encouraged with the use of scaffold implants that provide a substrate for new bone tissue to grow on. These scaffolds are usually made from a mineral called hydroxyapatite, which has a similar structure and composition to human bone tissue. 

However, osteosarcoma can recur in growing bone tissue, so a scaffold that inhibits the growth of cancer cells, but not of healthy cells, would improve the success of such treatment. The new material, developed by researchers in India, Saudi Arabia and Malaysia, aimed to address this need. The team investigated the use of a hydroxyapatite scaffold reinforced with poly(xylitol sebacate) (PXS) and loaded with capsaicin, a compound found in chilli peppers that has long been considered to have an anti-cancer effect, to prevent osteosarcoma recurrence. 

The researchers first analysed the properties of their composite material with a variety of imaging techniques. They confirmed that the hydroxyapatite–PXS scaffold had formed the expected structure, and that capsaicin was present on the surface of the scaffold. They also demonstrated sustained capsaicin release from the scaffold over a period of ten days. 

Once the properties of the scaffold had been established, the team assessed how osteosarcoma cells and the cells that produce bone tissue, called osteoblasts, reacted to the scaffold in culture. 

Osteoblasts were not affected by the scaffold itself, demonstrating that it is not toxic, or by the presence of capsaicin. By contrast, while osteosarcoma cells were not affected by the scaffold itself, their growth was inhibited by the presence of capsaicin on the scaffold. The mechanisms behind capsaicin’s anti-cancer effect are not known, but the team determined that it increased production of damaging reactive oxygen species in osteosarcoma cells, and induced the in-built cell death programme called apoptosis. 

The researchers conclude that the ability of the capsaicin-loaded scaffold to kill and restrict the growth of osteosarcoma cells, while not affecting the growth of healthy bone tissue, means it has potential for use in tissue engineering to simultaneously repair bone and prevent the recurrence of osteosarcoma.

1. Sumathra, M., Rajan M., Alyahya, S. A., Alharbi, N. S., Kadaikunnan, S. & Kumar, S. S. Development of self-repair nano-rod scaffold materials for implantation of osteosarcoma affected bone tissue. New Journal of Chemistry (2017) | article