Childhood and adolescence are almost synonymous with broken bones and fractures. To facilitate bone healing and growth, a team of French researchers has developed an innovative, self-setting foam that could help regenerate broken and defective bones much faster than traditional methods. What is more, this injectable biomaterial could pave the way for minimally-invasive bone repair surgeries, and possibly even a cure for osteoporosis.
70-percent of our bones are composed of a particular calcium phosphate mineral, known as hydroxyapatite. Traditionally, doctors have relied on the use of calcium phosphate cements (CPCs) to repair bone defects and fractures. Widely used in orthopedic and trauma surgeries, these self-setting bone substitutes have several impressive features, including injectability and biocompatibility. Being microporous, CPCs allow nutrients to flow through the bones, thereby accelerating their regeneration.
Over the years, scientists have struggled to introduce macroporosity – basically the presence of cavities and pores larger than 50 nanometers – into conventional bone cements. According to researchers, macroporous CPCs assist bone regeneration and also, strengthen cancellous bone, which is a type of spongy and flexible tissue that degenerates with the progression of osteoporosis. Although such materials do indeed exist, they usually have very poor mechanical properties, and are quite unsuitable for use in surgeries.
As part of a new research, scientists at the University of Nantes have come up with a special, injectable foam that doubles as a macroporous, self-setting bone cement. Created using silanised-hydroxypropyl methylcellulose (Si-HPMC) hydrogel as the foaming agent for adding air bubbles into the mixture, the material has been found to facilitate bone repair and growth. Speaking about the research, recently published in the Acta Biomaterialia journal, Pierre Weiss said:
Our approach is simple and gives us really good results in terms of mechanical properties and macroporous structures.
The breakthrough follows the team’s previous attempts, which involved adding a special Si-HPMC hydrogel to traditional CPCs, as a way of improving their mechanical properties. While preparing the hydrogel using syringes, however, air bubbles appeared in the resultant mixture, and were found to be difficult to remove. These air bubbles, according to the researchers, provided macroporosity to the bone cements.
To create the foam, the scientists started with two separate syringes, containing CPC and Si-HPMC solutions, respectively. Following that, air was pumped into the CPC-filled synringe. When joined by means of a connector, the contents of the syringes and air combined to form a frothy, homogenous, non-toxic material. Talking about the breakthrough, Weiss added:
We knew that both biomaterials are biocompatible separately but we didn’t know how the body would react with a combination of both.
To test the efficacy of the foam in terms of bone regeneration, the team conducted a series of in vivo tests, in which the cavities in the defective thigh bones of two rabbits were filled with the new-developed biomaterial. As expected, the foam helped facilitate bone healing and growth, leading to the formation of a new bone in the central part of the implant sites. Weiss said:
We think this could be a good biomaterial, perhaps with active molecules, to act against osteoporosis locally. We need to determine the proof of concept in animal models.
Via: Chemistry World