Mesenchymal stem/progenitor cells developed in cultures from UC blood.

Background Whether umbilical cord blood (UCB) serves as a source of mesenchymal stem/progenitor cells (MSPC) is controversial. MSPC are the best candidates for cellular therapy of orthopedic skeletal tissues. In order to explore the possibility of UCB as a useful source of MSPC, we identified, expanded in culture, and characterized MSPC from UCB harvests on a large scale. Methods Mononuclear cells isolated from UCB harvests (n=411) were cultured in media supplemented with 10% FBS. MSPC-like cells cultured from each UCB harvest were expanded ex vivo by successive subcultivation. UCB harvests with a more than 1000-fold expanding capacity (n=9) were examined for surface Ag phenotypes and in vitro differentiation potentials into osteogenic, chondrogenic and adipogenic lineages. Results Ninety-five out of a total of 411 UCB units (23.1%) generated MSPC-like cells during cultivation. Nine UCB units (2.2%) yielded MSPC with more than 1000-fold expansion capacity. These cells positively expressed MSPC-related Ag, but did not express myeloid, histocompatibility or endothelial Ag. These cells also possessed multiple capacities for osteogenic, chondrogenic and adipogenic differentiation. Discussion Although the incidence of UCB harvests producing MSPC in culture was low, some of them showed a more than 1000-fold expanding capacity, which is enough in cell numbers to be an allogeneic source for cellular therapy. Our results may encourage the use of UCB as an attractive target for allogeneic cellular therapeutic options in tissue engineering.