Effective Action Distance Between Umbilical Cord Blood-derived Hematopoietic Stem Progenitor Cells And Human Adipose Derived Stem Cells

Hematopoietic stem progenitor cells (HSPCs) have been used for blood illness such as anaemia and leukaemia, and for gene therapy and immunity therapy etc. Therefore, the great importance of clinical application is greatly concerned by researchers and clinical doctors. Though a great deal of research work about ex-vivo expansion of HSPCs has been done, expansion results varied in a considerably wide range under different culture conditions because of the complicated relationship between them. And lots of culture parameters need to be investegaed deeply.The effective interval between hematopoietic stem progenitor cells and feeding cells is still in suspense. Therefore, in order to investigate the optimal communication distance between umbilical cord blood (UCB) derived hematopoietic stem progenitor cells (HSPCs) and human adipose derived stem cells (ADSCs), transwell co-culture protocol was applied and the distance between the two culture chambers was adjusted. UCB mononuclear cells (MNCs) were isolated by density gradient centrifugation over Ficoll (1.077 g/ml, proportion of 1:1～2 between the Ficoll and UCB) and centrifuged horizontally at 2500rpm for 30 minutes at room temperature. The HSPCs were cultured in the transwell with the inoculated density of 1×10~6cells/ml supported with the ADSCs of 2×10~5 cells/ml inoculated density in the 6 well-plate for 7 days. IMDM medium was used supplemented with 12.5% horse serum and 12.5% fetal calf serum. The total cell number was counted and the cell morphology was viewed every 24h by the hemacytometer and inverted microscope, and the cell growth curves were thus obtained. Moreover, the expanded cells were identified with flow cytometer and through inducing them to multi-differentiate.The results show that there exists an optimal communication distance about 350μm between these two kinds of stem cells during their co-culture. At this distance the expansion fold of the UCB MNCs becomes the maximum of 15.1±0.2, and the CD34~+ cells can be expanded by 5.0±0.1.