INTRODUCTION: Stem cells derived from diabetes patients often loose most of their regenerative potential. Aims of this study were: 1) investigate the epigenetic basis of diabetes-dependent alterations in cardiac stromal cells (CStC) obtained from diabetes patients (D-CStC); 2) identify potential pharmacological interventions to restore their function.
METHODS AND RESULTS: CStC were isolated from volunteer normoglycaemic (N=12) and type-2 diabetic patients (D-CStC, N=8) and long-term cultured in DMEM, 20% fetal bovine serum at normal glucose concentration (5 mM). In this condition, D-CStC revealed impaired proliferation (3 fold reduction), compared to controls, marked by reduced histone H3 serine 10 phosphorylation (H3S10P), decreased ability to form capillary like-structure and the presence of senescence-associated acidic beta-galactosidase. A global histone code profiling indicated a marked reduction in histone H3 Lysine 9 and 14 acetylation (H3K9Ac; H3K14Ac) and a relative increase in H3 Lysine 9 and 27 trimethylation (H3K9me3; H3K27me3), modifications commonly associated to chromatin condensation and gene repression. This finding was further supported by a down-regulation of the P300/CBP-associated factor (PCAF) paralleled by a decrease in total histone acetyl-transferase (HAT) activity. In this condition, a high level of DNA CpG highlands hypermethylation was detected at gene loci involved in cell proliferation including CDK2, CDK4, CDKN1B, CCNB1 and MCM2. Remarkably, treatment with the pro-acetylation compound SPV106, a PCAF-selective activator, restored H3K9Ac and H3K14Ac at normal level, reduced H3K9me3 global content, abolished DNA CpG hypermethylation and rescued D-CStC proliferation and capillary-like structure formation.
CONCLUSIONS: Taken altogether our results suggest that the diabetes-associated metabolic syndrome permanently hits D-CStC determining chromatin structure and functional alterations which could be reversed by epigenetically active drugs
