Synthetic Bone Graft Recruits Stem Cells for Faster Bone Healing

They found that microporous ceramic particles composed of calcium phosphate--the primary component of bone ash--induced stem cells to develop into bone cells in the test tube and stimulated bone growth in live tissue in mice, dogs, and sheep. According to the researchers, the study shows that the microporosity of the ceramic biomaterials correlates to their propensity to stimulate osteogenic differentiation of stem cells in vitro, as well as bone induction in vivo.

When researchers packed the ceramic particles into a large bone defect in sheep, the bone healed similarly to implants constructed from the animals' own bone, thus demonstrating that osteoinductive ceramics are equally efficient in bone repair as autologous bone grafts. A further benefit is that unlike commercial products that contain artificial GFs, the ceramic biomaterials do not have unwanted side effects such as causing bone fragments to form in nearby soft tissue, such as muscle. The study was published in the August 3, 2010, issue of the Proceedings of the National Academy of Sciences (PNAS).

"The rate of bone repair we see with these materials rivals that of traditional grafts using a patients' own bone,” said lead author Professor Joost de Bruijn, Ph.D., from the school of engineering and materials science at the Queen Mary, University of London. "And what sets it apart from other synthetic graft substitutes is its ability to attract stem cells and the body's natural growth factors, which coincide to form new, strong, natural bone around an artificial graft.”

Although the researchers have not yet identified the mechanism by which these osteoinductive ceramics drive bone growth in the synthetic implants, they note that variations in the ceramic material's chemistry, microporosity, microstructure, and degradation influence the graft's performance.

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