Umbilical Cord Mesenchymal Stem Cells: Adjuvants for Human Cell Transplantation

A, Expansion of UC-MSCs in various culture media. Fresh cord pieces were minced and those particles were cryopreserved in 10% DMSO and autologous cord plasma to avoid exposure of UC-MSCs to allogeneic media. After thawing, UC-MSCs were expanded in 20% FBS, 10% FBS, 20% HS, 10% HS, or autologous cord plasma. The number of expanded cells is plotted on the y-axis. All sera were heat-inactivated and supplemented with either RPMI 1640 or X-Vivo10. FBS at 20% resulted in the best expansion. No difference was seen for RPMI 1640 or X-Vivo10 as base media. Results from 1 of 3 representative experiments are presented. B, Microscopic view of UC-MSCs cultured in either 20% FBS/RPMI 1640 or 20% HS/RPMI 1640 appearance (original magnification × 40). In HS, the MSCs tend to form clumps, with less UC-MSCs becoming adherent. Spreading of the clumps can be observed when plucked and replated in 20% FBS.

Engraftment of human BM cells in NOD/SCID mice. The mice underwent transplantation (intravenous injection) either with UCB cells at 10⁶ alone or together with 10⁶ UC-MSCs (A) or with CD34-enriched UCB cells at 10⁴ alone or together with 10⁶ UC-MSCs (B). Human cell engraftment was assessed at 6-8 weeks according to the human CD45 marker. Co-transplanted UC-MSCs augmented engraftment for transplantation of unfractionated UCB cells as well as CD34 selected hematopoietic precursors.

Transfection of UC-MSCs with the GFP reporter gene. Adherent cells were transfected using the BioRad electroporator with either cDNA or mRNA at different voltages and capacitance, as indicated. mRNA showed higher transfection efficiency than cDNA, with expression of the GFP gene maintained for several days.