Effects of demineralized bone matrix on proliferation and osteogenic differentiation of mesenchymal stem cells from human umbilical cord.

BACKGROUND: Mesenchymal stem cells or mesenchymal progenitor cells are defined as self-renewable, multipotent progenitor cells with the unlimited capacity to differentiate into multiple lineage-specific cells that form bone, cartilage, fat, and muscle tissues. Demineralized bone matrix (DBM) has been extensively utilized in orthopaedic, periodontal, and maxillofacial applications and widely investigated as a biomaterial to promote new bone formation. OBJECTIVE: To isolate and characterize umbilical cord mesenchymal stem (UCMS) cells and examine the biological activity of DBM in the UCMS cells MATERIAL AND METHOD: UCMS cells were obtained from human umbilical cord culture. Cells were treated with or without DBM over 7 days of culture. Cell proliferation was examined by direct cell counting. Osteogenic differentiation of the UCMS cells was analysed with alkaline phosphatase staining assay. RESULTS: Phenotypic characteristics ofhuman UCMS cells were spindle and stellate shapes with fine homogenous cytoplasm, typically associated with fibroblast-like cells. The control cells (without DBM treatment) exhibited a spindle shape with little extracellular matrix, whereas the DBM treated cells appeared shortened and flattened, and they were surrounded by extracellular matrix. DBM inhibited the growth of the UCMS cells by 50%, as determined by direct cell counting. Morphologic and histochemical studies confirmed that DBM had a strong stimulatory effect on the alkaline phosphatase activities of UCMS cells, a very early marker of cell differentiation into the osteogenic lineage. CONCLUSION: Mesenchymal progenitor cells derived from umbilical cord could differentiate along an osteogenic lineage and thus provide an alternative source for cell-based therapies and tissue engineering strategies.

Content of bone morphogenetic protein-4 in human demineralized bone: relationship to donor age and ability to induce new bone formation.

BACKGROUND: Bone morphogenetic proteins (BMPs) are also called growth and differentiation factors (GDFs) and form a subfamily of related proteins within the TGF-beta superfamily. BMP-4 is one ofmultifuntional growth factors with pleiotropic roles in many different cell types and is predominantly present in human bone tissue. OBJECTIVES: To analyze the content of extractable BMP-4 in human demineralized bone as a function of age. MATERIAL AND METHOD: Bone samples were ground and demineralized by exposure to 0.5 N HCl and then extracted by collagenase digestion. Extractable BMP-4 was analyzed using a commercially available enzyme-linked immunosorbent assay (ELISA). RESULTS: 63 samples of demineralized bone matrix (DBM) derived from 36 men and 27 women between the ages of 15-65 years. The extractable BMP-4 content appears to be age-dependent, with DBM from younger donors being most likely to have higher BMP-4 quantity. In addition, DBM with high osteoinductivity contained greater amounts of extractable BMP-4 than DBM samples with low osteoinductivity. CONCLUSION: The BMP-4 in demineralized bone undergoes age-related decrease that may contribute to the reduction of bone volume observed with aging.