Tissue engineering of bone - Cell based strategies

Skeletal tissue regeneration requires the interaction of three basic biolog ic elements: cells, growth and differentiation factors, and extracellular m atrix scaffolds. Therapeutic approaches for tissue engineered repair of bon e defects have attempted to mimic the natural process of bone repair by del ivering a source of cells capable of differentiating into osteoblasts, indu ctive growth and differentiation factors, or bioresorbable scaffolding matr ices to support cellular attachment, migration, and proliferation. Sophisti cated designs even have tried to combine two or more of these elements. The development of cell based approaches has advanced dramatically in recent y ears as an understanding of musculoskeletal cell biology improves. Cell bas ed approaches do not depend on the presence of local osteoprogenitors for t he synthesis of new bone and, as a result, they particularly are attractive for patients who hale a diminished pool of these progenitors, or in whom t he host tissue bed has been compromised. This review highlights the develop ment of cell based approaches for the tissue engineering of bone, and offer s perspectives on the optimal elements for success, Although logistical and regulatory issues remain to be solved, cell based therapies for the repair of clinically significant bone defects rapidly are approaching clinical fe asibility.