Stem cells in the treatment of muscle and connective tissue diseases.

Current data indicate the existence of two types of postnatal stem cells. Tissue non-specific stem cells are haematopoietic in origin and can differentiate into different blood lineages. In contrast, tissue-specific stem cells preferentially differentiate into cells of the residing tissue, although they also possess a limited ability to turn into other lineages. In terms of therapeutic potential, unmodified muscle-derived stem cells have been proven capable of regenerating dystrophic muscle. Furthermore, when genetically modified to express growth factors, these cells are versatile in promoting bone healing. This also occurs with mesenchymal stem cells, which have been used in an attempt to repair defects of cartilage and ligaments. Thus, stem-cell-based therapy--particularly genetically engineered therapy--holds great potential for the treatment of a variety of disorders and conditions affecting the muscle and connective tissue.