Human umbilical cord blood (hUCB) is well known for a good source of hematopoietic stem cells (HSCs). However, the presence of mesenchymal stem cells (MSCs) in hUCB is still not well approved by many authors. We hereby report the isolation and characterization of MSCs from hUCB, as well as their differentiation into osteogenic, chondrogenic and adipogenic lineages.

Mononuclear cells were isolated from each hUCB harvest (n=411) by density gradient centrifugation, and suspended in -minimum essential medium supplemented with 10% fetal bovine serum (FBS). The cell population was expanded by successive sub-cultivation under the same condition. The cell population that showed more than 1, 000-fold expansion at fifth to eighth passage was inspected with known surface antigens of MSCs and other cell lineage. The isolated MSCs were cultured in osteogenic, chondrogenic, and adipogenic condition to identify their potential to differentiate into different mesenchymal cell lineage.

Ninety five out of 411 hUCB units (23.1%) generated the MSC-like cell population during initial cultivation. Nine cell populations (2.2%) showed more than 1, 000-fold expansion capacity at fifth to eighth passage. These cells positively expressed all known MSC-related antigens. They did not express any of myeloid, endothelial, or histo-compatibility antigens. All of the MSCs isolated showed the potential to differentiate into osteogenic, chondrogenic, and adipogenic lineages.

Our study supports that hUCB does contain MSCs, which can be differentiated into different cell lineages. We believe hUCB will be a good source of MSCs with the advantage of availability and relative abundance. We think hUCB should not be considered as a medical waste, and it will serve as a good source of cells for tissue engineering and cellular therapy in the future.