Expression of Cadherins in Bone Marrow Stromal Cells Affects Capacity Supporting Expansion of CD34+ Cord Blood Cells.

Ex vivo expansion of hematopoietic progenitor cells (HPCs) has been used to circumvent the limitation of umbilical cord blood applied on adult HPC transplantation and may facilitate ex vivo gene manipulation. Nonetheless, the nature of these signals provided by the stromal microenvironment and mechanisms by which stromal cells regulate the growth of stem cells remain to be defined. With the help of retrovirally-expressing human telomerase reverse transcriptase (hTERT) in marrow stromal cells, we isolated 16 human bone marrow stromal cell lines. After a 7-day short stromal cells-dependent co-culture, the cord blood CD34+ cells were 1.0- to 14.5-fold expanded. Among the adhesion molecules in stromal cells examined, expression of N-cadherin and P-cadherin in stromal cells were found to correlate with capacities of stromal cells to support cord blood HPC expansion and be predictive of HPC-expanding capacities.