Potential of bone marrow stromal stem cells to repair bone defects and fractures

In the emerging age of cellular therapy, bone marrow stromal stem cells (BMSSC) represent a population of cells with enormous therapeutic potential. Whilst in their relative infancy, numerous studies suggest that BMSSC are capable of restoring cardiac function, neural regeneration, defects of articular cartilage, improving hematopoietic engraftment and most promisingly, the repair of large osseous defects. Segmental defects of bone, or non-union fractures represent a significant and intractable clinical problem, in which the volume of bone loss results in delayed healing or non-union. Currently there are several therapies employed to facilitate osseous repair, ranging from the use of autograft bone, allograft bone and an array of artificial bone substitutes. However, all these approaches are often associated with various limitations making it difficult to predict outcome. Major problems include secondary site morbidity associated with autologous bone, availability and suitability of allogeneic bone, and the variable osteo-conductivity of different biomaterials. The ability to generate osteogenic progenitor cells derived from culture expanded BMSSC has provided, for the first time, the potential to overcome many of these limitations. When used in conjunction with existing osteo-conductive bone void fillers, BMMSC may not only facilitate the repair of large segemental defects following disease or trauma, but may also provide a cellular therapy for spinal fusion and craniofacial reconstructive surgery. The following review outlines the possible applications and highlights the potential limitations of BMSSC for developing novel tissue engineering approaches for orthopaedic applications.