Pierre Weiss and his team at the University of Nantes have been working on improving the way broken and degenerating bones are treated. One of major components that make up bones is calcium, and for over one-hundred years calcium phosphates have been used as substitutes for bone grafts and repairs. While it’s been a proven way to help set and heal bones, Weiss wanted to find a better and less invasive way.
The idea of injectable calcium phosphate cements (CPCs) has been floating around since at least 2004, but one of the major problems faced was creating a CPC that could be injected into a bone while retaining the macroporous qualities — that is, the ability to retain the sponge-like qualities found in the bone tissue around the long ends of bones near the pelvis, skull, ribs, and other areas. Another benefit of macroporosity is how quickly a bone will regenerate once the CPC has been introduced. If the team could find a way to overcome this and reintroduce macroporosity into their CPC injectable, then they would unlock the secret to better bone restoration.
So, they went to work. But it was by accident that they found by introducing silanized-hydroxypropyl methylcellulosem which is a polymer solution, into the CPC, it created a foam. Originally Weiss and his team had added the Si-HPMC directly to the CPC, and air bubbles were formed. They tried to remove them, but found the it too difficult. Nearly giving up on it, two other members chose to run with the experiment a bit further.
Weizhen Liu and Jingtao Zhang, postdoctoral researchers at the University, put the CPC and Si-HPMC compounds in individual syringes, added air, and mixed it all together. Like a really complex two-part epoxy glue. The air bubbles mixed so well that it created a foam, which was able to be injected and keep the CPCs mechanical properties stable.
Tests were done, and the results show that Weiss and his team are well on their way to making a injectable foam for bones that may be the way of bone repair of the future.