In order to investigate the effects of in vitro co-culture distance between umbilical cord blood-derived hematopoietic stem/progenitor cells(HS/PCs) and human adipose derived stem cells(h-ADSCs) on the expansion of HS/PCs and the stem cell properties of h-ADSCs,a novel transwell co-culture protocol in which the distance between the two culture chambers could be adjusted was designed.Sand papers with different specifications were utilized to adjust the cellular action distance between two kinds of cells ment...