| Expansion of haematopoietic stem/progenitor cells (HS/PCs) has been studied intensively. Although significant quantitative increase in cell numbers has been achieved, self-renewal and transplantation capacity of expanded cells are still the problems for most strategies, such as several week liquid culture with different cytokine combinations or stromal cells feeder layers. In other words, human transplantation of expanded cells remains to be validated althoug quantitative expansion of hematopoietic cells has been achieved.Recently, a synthetic, cell-permeable indirubin derivative, 6-bromoindirubin-3’-oxime (BIO)[1] has been reported to not only maintain the self-renewal capacity but also sustain the differentiation potential of human and mouse embryonic stem cells (HESCs and MESCs, respectively). The effect of this compound on the expansion of human adult HS/PCs and its potential impact on future haematopoietic stem cell transplant are yet to be uncovered. In this study we compared the ex vivo expansion outcome of HS/PCs in the absence or presence of BIO by short-term liquid culture, using freshly isolated CD34+ cells from human cord blood (CB). The expanded cells were assessed for cellular characteristics by surface antigen analysis, colony-forming cell assay (CFC assay), and long-term liquid culture assay. We showed that KL (c-kit ligand; SCF) together with BIO(0.2μM) but not MeBIO (1-methyl-6-bromoindirubin-3’-oxime) effectively expanded human cord blood total HS/PCs by 1.49±0.45 folds, CD34+ HS/PCs by 1.42±0.43 folds after liquid culture for 2.5 days. In addition, the number of CFC (colony forming cells) is also increased by 3.87±1.14 folds compared to day 0 freshely isolated CD34+ cells. Long-term liquid culture proved multileage differentiation potential of the expanded cells. Although lack of animal transplantation experiment, the results show that KL together with BIO could be a favorable combination to expand HS/PCs to provide feasible new ways for stem cell treatment program. |
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