DIFFERENTIATION FACTORS INDUCE EXPRESSION OF MUSCLE, FAT, CARTILAGE, AND BONE IN A CLONE OF MOUSE PLURIPOTENT MESENCHYMAL STEM-CELLS

Growth factors have been used experimentally to accelerate wound heali ng by increasing scar tissue formation at a wound site. These studies suggest that simulation of fibroblastic differentiation and proliferat ion are essential components of adult tissue repair. Recent studies re port the presence of mesenchymal stem cells within granulation tissue and as connective tissue-resident stem cells. This suggests that mesen chymal stem cells as well as fibroblasts may contribute to wound heali ng and repair. To determine the potential for mesenchymal stem cells t o contribute to nonfibrogenic tissue repair, a clonal population of mu rine mesenchymal stem cells was examined with dexamethasone, a general differentiation agent, and muscle morphogenetic protein, a specific d ifferentiation-inducing agent. Dexamethasone induced the expression of phenotypic markers for fat, cartilage, and bone in the stem cells. Mu scle morphogenetic protein induced the expression of mRNAs for the mus cle specific regulatory genes MyoD1 and myogenin in these cells. These results suggest that pluripotent mesenchymal stem cells within connec tive tissue compartments and granulation tissue have the potential to contribute to functional tissue restoration, rather than contributing solely to fibrogenic scar tissue formation during tissue repair.