Pioglitazone strengthen therapeutic effect of adipose-derived regenerative cells against ischemic cardiomyopathy through enhanced expression of adiponectin and modulation of macrophage phenotype.

Background: The efficacy of cell transplantation in heart failure is reportedly modest, but adjuvant drugs combined with cell therapy may improve this efficacy. Peroxisome proliferator-activated receptor (PPAR)γ, one of the hypoglycemic medicine for diabetes mellitus, reportedly enhances cytokine production in adipose tissue-derived regenerative cells (ADRCs). We hypothesized that combined administration of PPARγ agonists and ADRCs may enhance the paracrine effects of adiponectin (APN), leading to functional recovery in a chronic myocardial infarction (MI) model.

Methods: ADRCs were isolated from adipose tissues of adult rats by gradient centrifugation and embedded in bio-compatible fibrin-glue to produce ADRCs grafts. In the in vitro study, the ADRCs grafts released APN, which was significantly enhanced by the PPARγ agonist (PGZ, pioglitazone). Transplantation of ADRCs grafts (group A), ADRCs mixed with PGZ (group AP), APN knockdown-ADRCs (group Si) or PGZ (group P) onto the epicardium or a sham operation (group C) was performed (n = 10-20 per group).

Results: The AP group showed significant improvement in ejection fraction compared to that in the other groups. In the AP group, a significantly larger number of M2-polarized macrophages was detected and existed for a significantly longer duration in the infarct area. Furthermore, comparing Si group and P group, western blotting of T-cadherin revealed that exogenous APN and local expression of T-cadherin were essential to this histological change and recovery of cardiac function.

Conclusions: Combined administration of PPARγ agonist and ADRSCs activated M2-polarized macrophages with enhancement of APN paracrine effects and lead to better cardiac function in a rat infarction model.