Multilineage differentiation activity by cells isolated from umbilical cord blood: Expression of bone, fat, and neural markers

The stromal cell population in bone marrow has been the focus of much atten tion since it has been shown that this cell population can be expanded and differentiated into cells with the phenotype of bone, cartilage, muscle, st roma, neural, and fat cells. We evaluated umbilical cord blood (UCB) for th e presence of these cells. From the mononuclear fraction of UCB, we demonst rated the presence of a subset of cells that have been maintained in contin uous culture for more than 6 months (> 10 passages). These adherent cell po pulations express adhesion molecules CD13(+), CD29(+), and CD44(+), but not antigens of hematopoietic differentiation. Exposure of these cells to oste ogenic agents resulted in an increase in expression of alkaline phosphatase and the appearance of hydroxyapatite nodules by Van Kossa staining. Incuba tion with adipogenic agents resulted in morphological change and staining w ith Oil Red O. In addition, when exposed to basic fibroblast growth factor and human epidermal growth factor the cells underwent changes consistent wi th 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 marro w, cord blood contains a population of cells that can be expanded in cultur e and are able to express the phenotype of multiple lineages. Cord blood mu ltilineage cells are slower to establish in culture, have a lower precursor frequency and a lower level of bone antigen expression, and lack constitut ive expression of neural antigens when compared to bone marrow; suggesting a more primitive population. Cord blood may prove to be a new source of cel ls for cellular therapeutics for stromal, bone, and, potentially, neural re pair.