<p><b>OBJECTIVE</b>To study the
role of the
feeder layer cells as niche in the process of expansion of late
endothelial progenitor cell in vitro.</p><p><b>
METHODS</b>We cultured mononuclear
cells (MNC)from
human peripheral
blood (PB)on the plate with the
feeder layer cells which were irradiated late
endothelial progenitor cells(EPC)or
human umbilical vein endothelial cells (HUVEC) by EGM-2. After 21 days, the numbers of obtained late EPC colonies were counted separately, and their
surface antigen of the late EPC was verified by
fluorescence-activated
cell sorter (FACS)
analysis, and their
ability of forming vessel structure with Matrigel
in vitro. The differentiation of single
stem cell on the
feeder layer cell was traced by video-
microscopy.</p><p><b>RESULTS</b>After 21 days of
culture,(40.0±3.9)and(39.3±3.1)late EPC colonies that MNC of a hundred milliliter PB were cultured, respectively, on the
feeder layer cells of EPC and HUVEC were much more than (2.0±1.3) colonies cultured on without the
feeder layer cells (all P <0.05). These
cells also expressed CD31,CD34,eNOS,FLt-1,P1H12,Sendo,VE
cadherin,and CD117, as shown by FACS
analysis. Furthermore, they formed vessel structure with Matrigel
in vitro. The video-
microscopy showed the
asymmetric cell division was participated by the
feeder layer cell during the expansion of single
stem cell.</p><p><b>CONCLUSION</b>The massive expansion of late EPC can be achieved by the
provision of the
feeder layer cells, which may be involved in the
stem cell asymmetric cell division.</p>