Human umbilical cord bloods, which could be taken during the delivery are utilized as a source of hematopoietic stem cells. Also in cord blood, there are several kinds of stem cells such as endothelial and mesenchymal stem cells.

We isolated the mesenchymal stem cells from human umbilical cord bloods and confirmed the differentiation of these cells into osteoblast progenitor cells. The mesenchymal stem cells derived from umbilical cord blood have the ability to differentiate into specific tissue cells, which is one of characteristics of stem cells. These cells were originated from the multipolar shaped cells out of adherent cells of the umbilical cord blood mononuclear cell culture.

The mesenchymal stem cells expressed cell surface antigen CD13, CD90, CD102, CD105, α-smooth muscle actin and cytoplasmic antigen vimentine. Having cultrued these cells in bone formation media, we observed the formation of extracellular matrix and the expression of alkaline phosphatase and of mRNA of cbfa-1, ostoecalcin and type I collagen.

From these results we concluded that the cells isolated from the umbilical cord blood were mesenchymal stem cells, which we could differentiate into osteoblast when cultured in bone formation media. In short, it is suggested that these cells could be used as a new source of stem cells, which has the probability to alternate the embryonic stem cells.