RESUMEN
<p><b>AIM</b>To study the effects of cryopreservation length on the proliferative potential of hematopoietic cells derived from cord blood.</p><p><b>METHODS</b>Using Dextran-40 and 10% DMSO as cryoprotectants, separated nuclear cells were stored in liquid nitrogen after they were freezed according programme. One month or 4 months later, they were thawed and expanded in serum-free medium for culture and expansion of hematopoietic cell (SFEM) for 5 weeks. Dynamic results were detected every week.</p><p><b>RESULTS</b>At the 5th week of expanding, TNC were expanded for 1499.0 +/- 115.6-folds and 1513.0 +/- 110.4-folds, respectively. CD34+ cells and CFCs reached to their highest level at the 2nd week and at the 3rd week. CD34+ cells were expanded for 63.8 +/- 6.1-folds and 62.4 +/- 5.7-folds, respectively. CFCs were expanded for 53.8 +/- 6.3-folds and 54.8 +/- 6.7-folds, respectively. Between the two kinds of cells, statistical significant difference in proliferative potential wasn't detected.</p><p><b>CONCLUSION</b>In ideal cryopreservative condition, the cryopreservation length would do not affect the proliferative potential of cord blood hematopoietic cells.</p>