Bone Marrow Derived Mesenchymal Stem Cells Enhance In Vitro Expansion Of Umbilical Cord CD34～+ Progenitor Cells In A Serum-free Culture System

ObjectiveTo investigate the effectiveness of in vitro expansion of human cord blood stem cell (CBSC) with a serum-free system and co-culture with human bone marrow derived mesenchymal stem cell (BM-MSC). MethodsAfter 2 weeks' culture in the serum-free medium containing thrombopoietin (TPO), flt3/flk2 ligand (FL), stem cell factor (SCF) and granulocyte-colony stimulating factor (G-CSF), the output of total cells (TC), CD34+, colony forming units (CFU), and long-term culture-initiating cells were evaluated between the culture systems with or without BM-MSC .The results were also evaluated for 7-day or 14-day's culture in vitro in the expansion system with the cytokines and BM-MSC. ResultsIn the presence of both BM-MSC and four cytokines mentioned above, CBSC produced an expansion of 427-fold in TC, 39-fold in CD34+, 125-fold in CFU-C, 104-fold in CFU-GM and 16-fold in LTC-IC, after 14 days of incubation. By contrast, when cultured merely in thepresence of the cytokines, the cell expansion for TC, CD34+, CFU-C and CFU-GM were increased by 62-fold, 11-fold, 25-fold and 24-fold, respectively. Notably, the output of LTC-IC is only 0.8-fold of the input. There is significant difference between the two groups. (P<0.05)While there is no or slight increase in TC in the control group, and cannot detect any CD34+, CFU-C and CFU-GM after 7-day or 14-day's culture. CBSC produced an expansion of 87-fold in TC, 16-fold in CD34+, 15-fold in CFU-C and 26-fold in CFU-GM after 7-day's incubation In the presence of both BM-MSC and the four cytokines, there is significant difference between the group expanded for 7-day and the 14-day one. (P<0.01) ConclusionOur serum-free and co-culture system was shown to achieve admirable results for in vitro expansion of CBSC, and which may probably be employed for clinical purpose.