DNA Methylation and Hydroxymethylation Profile of CD34⁺-Enriched Cell Products Intended for Autologous CD34⁺ Cell Transplantation

Abstract

Epigenetic dysregulation has been shown to limit functional capacity of aging hematopoietic stem cells, which may contribute to impaired outcome of hematopoietic stem cell-based therapies. The aim of our study was to gain better insight into the epigenetic profile of CD34-enriched cell products intended for autologous CD34 cell transplantation in patients with cardiomyopathy. We found global DNA methylation content significantly higher in immunoselected CD34 cells compared to leukocytes in leukapheresis products (2.33 ± 1.03% vs. 1.84 ± 0.86%, p = 0.04). Global DNA hydroxymethylation content did not differ between CD34 cells and leukocytes (p = 0.30). By measuring methylation levels of 94 stem cell transcription factors on a ready-to-use array, we identified 15 factors in which average promoter methylation was significantly different between leukocytes and CD34 cells. The difference was highest for HOXC12 (58.18 ± 6.47% vs. 13.34 ± 24.18%, p = 0.0009) and NR2F2 (51.65 ± 25.89% vs. 7.66 ± 21.43%, p = 0.0045) genes. Our findings suggest that global DNA methylation and hydroxymethylation patterns as well as target methylation profile of selected genes in CD34-enriched cell products do not differ significantly compared to leukapheresis products and, thus, can tell us little about the functional capacity and regenerative properties of CD34 cells. Future studies should examine other CD34 cell graft characteristics, which may serve as prognostic tools for autologous CD34 cell transplantation.