Mitochondrial superoxide reduction and cytokine secretion skewing by carbon nanotube scaffolds enhance ex vivo expansion of human cord blood hematopoietic progenitors

In this study, we report that surface functional groups of single walled carbon nanotubes (f-SWCNT) are critical formediating survival and ex vivo expansion of hematopoietic stem and progenitor cells (HSPC) in human umbilical cord blood (UCB). In comparison to amide (-O-NH2) and polyethylene-glycol (-PEG) functionalized SWCNT, carboxylic acid (-COOH) variants gave optimal viability support which correlated with maximal reduction of lethal mitochondrial superoxides in HSPC. Cytokine array illustrated that f-SWCNT-COOH maintained higher proportion of HSPC associated cytokines and minimal level of differentiation promoting factors. Transplantation of f-SWCNT-COOH expanded grafts in sublethally irradiated immunodeficient mice resulted in higher engraftment of HSPC in bone marrow compared to control when they were co-transplanted with non-expanded cells from the same UCB. Expanded grafts mediated higher survival rate of mice compared to non-expanded grafts due to lower graft-versus-host-disease which is likely a consequence of proportion of immune cells in the grafts. From the Clinical Editor: Umbilical cord blood (UCB) is a potential source of hematopoietic stem and progenitor (HSPC) cells. One major hurdle for its clinical use is the insufficient yield of cell number. The authors in this study elegantly demonstrated the importance of various functional groups on single-walled carbon nanotubes (f-SWCNT) in enhancing ex vivo expansion of HSPC in UCB. The findings may pave a way for having UCB as a source for HSPC for clinical use in the future. (C) 2015 Elsevier Inc. All rights reserved.