Effects of CXCR1 and CXCR2 inhibition on expansion and differentiation of umbilical cord blood CD133+ cells into megakaryocyte progenitor cells

ObjectiveThere have been various reports on the roles of CXC receptors (CXCR) in modulation of hematopoiesis. In the present study, we investigated the effects of CXCR1 and/or CXCR2 inhibition on expansion and differentiation of umbilical cord blood (UCB) CD133+ cells into megakaryocytic progenitors.Materials and methodsPurified UCB CD133+ cells were cultured in a serum-free liquid culture either in the presence or absence of neutralizing anti-CXCR1 and/or anti-CXCR2 antibodies in combination with a conventional cytokine cocktail for up to 14 days. Expression of megakaryocytic lineage markers (CD41 and CD61) and determination of ploidy level were determined by flowcytometry. In addition, colony-forming unit assay was performed using CD133+ cultures in serum-free collagen-based medium containing the cytokine cocktail plus neutralizing CXCR1 and -R2 antibodies. Colony forming unit-megakaryocyte (CFU-MKs) and non-MKs were counted after immunocytochemistry staining on day 12.ResultsWe show that while simultaneous inhibition of both CXCR1 and -R2 causes a significant reduction in the fold expansion of UCB CD133+ cells, it also leads to an increase in percentages of CD61+, CD41+, and CFU-MK populations.ConclusionCXCR1 and CXCR2 play significant roles in the suppression of megakaryopoiesis. We demonstrate that blocking of this suppressive effect by a simultaneous inhibition of both receptors can enhance the differentiation of UCB CD133+ cells into megakayocytic progenitors.

► We investigated effects of CXCR1/R2 on expansion and differentiation of CD133+ cells. ► Simultaneous inhibition of CXCR1/R2 causes a reduction in expansion of CD133+ cells. ► It also leads to an increase in percentages of CD61+, CD41+, and CFU-MK populations. ► Neutralization of CXCR1/R2 has no effect on DNA content of CD41+ and CD61+ cells. ► CXC neutralizing antibodies might overcome platelet recovery after transplantation.