The stromal cell population in bone marrow has been the focus of much attention since it has been shown that this cell population can be expanded and differentiated into cells with the phenotype of bone, cartilage, muscle, stroma, neural, and fat cells. We evaluated umbilical cord blood (UCB) for the presence of these cells. From the mononuclear fraction of UCB, we demonstrated the presence of a subset of cells that have been maintained in continuous culture for more than 6 months (>10 passages). These adherent cell populations express adhesion molecules CD13+, CD29+, and CD44+, but not antigens of hematopoietic differentiation. Exposure of these cells to osteogenic agents resulted in an increase in expression of alkaline phosphatase and the appearance of hydroxyapatite nodules by Von Kossa staining. Incubation with adipogenic agents resulted in morphological change and staining with Oil Red O. In addition, when exposed to basic fibroblast growth factor and human epidermal growth factor the cells underwent changes consistent with cells of neural origin. These changes were demonstrated by a combination of immunofluorescent labeling and Western immunoblots for neural-specific markers. Thus, similar to what has been previously reported with bone marrow, cord blood contains a population of cells that can be expanded in culture and are able to express the phenotype of multiple lineages. Cord blood multilineage cells are slower to establish in culture, have a lower precursor frequency and a lower level of bone antigen expression, and lack constitutive expression of neural antigens when compared to bone marrow, suggesting a more primitive population. Cord blood may prove to be a new source of cells for cellular therapeutics for stromal, bone, and, potentially, neural repair.

Rare cells are present in human umbilical cord blood that do not express the hematopoietic marker CD45 and in culture do not produce cells of hematopoietic lineage. These umbilical cord multipotent stem cells (UC-MC) behave as multilineage progenitor cells (stem cells) and can be expanded in tissue culture. Exposure to basic fibroblast growth factor (bFGF) and human epidermal growth factor (hEGF) for a minimum of 7 days in culture induces expression of neural and glial markers. Western immunoblots demonstrate expression of both β-tubulin III and glial fibrillary acidic protein (GFAP). Immunocytochemistry of the cells showed intense labeling to both compounds on the intracellular cytoskeleton. The oligodendrocyte cell surface marker galactocerebroside (Gal-C) was present on most cells. Many cells show dual labeling, expressing both neuronal and glial markers.