Stem cells and regenerative medicine for musculoskeletal tissue

Unfortunately, musculoskeletal conditions are now a leading cause of non-infectious disease and fractures, especially in the elderly population, can lead to significant morbidity and mortality. There are two main mechanisms of fracture healing, primary and secondary healing. The stability of the fracture, resulting strain at the fracture site, and distance between the broken ends affect the way the fracture heals and the outcome. In order to heal the fracture, new bone must be generated and this is done through recruitment of local and distant progenitor cells. Using a complicated network of signaling pathways, cells are recruited to the site of the fracture and coordinate their responses. Both innate qualities and the microenvironment affect the role of cells and therefore impact the rate and quality of the repaired bone. In cases of impaired fracture healing, physicians can use biomaterials to promote proper healing of fractures. There are many types of biomaterials, from autologous bone grafts to nanostructured autografts, and each type of material has its own strengths and weaknesses. This chapter gives an overview of the different stages of fracture healing, progenitor cells, signaling pathways, and biomaterials. While our knowledge of fracture healing has come a long way, there is still a lot that remains unclear and further research into signaling pathways and biomaterials should be done.