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Stem Cells. 2015 Jul;33(7):2169-81. doi: 10.1002/stem.1967. Epub 2015 May 26.

Chromatin Changes at the PPAR-γ2 Promoter During Bone Marrow-Derived Multipotent Stromal Cell Culture Correlate With Loss of Gene Activation Potential.

Author information

1
Cellular and Tissue Therapies Branch, Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, US Food and Drug Administration, Bethesda, Maryland, USA.

Abstract

Bone marrow-derived multipotent stromal cells (BM-MSCs) display a broad range of therapeutically valuable properties, including the capacity to form skeletal tissues and dampen immune system responses. However, to use BM-MSCs in a clinical setting, amplification is required, which may introduce epigenetic changes that affect biological properties. Here we used chromatin immunoprecipitation to compare post-translationally modified histones at a subset of gene promoters associated with developmental and environmental plasticity in BM-MSCs from multiple donors following culture expansion. At many locations, we observed localization of both transcriptionally permissive (H3K4me3) and repressive (H3K27me3) histone modifications. These chromatin signatures were consistent among BM-MSCs from multiple donors. Since promoter activity depends on the relative levels of H3K4me3 and H3K27me3, we examined the ratio of H3K4me3 to H3K27me3 (K4/K27) at promoters during culture expansion. The H3K4me3 to H3K27me3 ratios were maintained at most assayed promoters over time. The exception was the adipose-tissue specific promoter for the PPAR-γ2 isoform of PPAR-γ, which is a critical positive regulator of adipogenesis. At PPAR-γ2, we observed a change in K4/K27 levels favoring the repressed chromatin state during culture. This change correlated with diminished promoter activity in late passage cells exposed to adipogenic stimuli. In contrast to BM-MSCs and osteoblasts, lineage-restricted preadipocytes exhibited levels of H3K4me3 and H3K27me3 that favored the permissive chromatin state at PPAR-γ2. These results demonstrate that locus-specific changes in H3K4me3 and H3K27me3 levels can occur during BM-MSC culture that may affect their properties. Stem Cells 2015;33:2169-2181.

KEYWORDS:

Cell differentiation; Chromatin; Epigenomics; Gene expression regulation; Immunomodulation; Mesenchymal stromal cells

PMID:
25640287
DOI:
10.1002/stem.1967
[Indexed for MEDLINE]
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