Both cultured and freshly isolated adipose tissue-derived stem cells enhance cardiac function after acute myocardial infarction

We assessed whether freshly isolated human adipose tissue-derived cells (fhADCs) or cultured human adipose tissue-derived stem cells (hASCs) have beneficial effects on cardiac function after myocardial infarction (MI), whether the injected cells can survive long term, and whether their effects result from direct differentiation or paracrine mechanisms. Myocardial infarction was experimentally induced in severe combined immunodeficient mice, and either fhADCs, cultured hASCs, or phosphate-buffered saline was injected into the peri-infarct region. Myocardial function improved significantly in mice treated with hASCs or fhADCs 4 weeks after MI. Immunofluorescence revealed that grafted hASCs and fhADCs underwent cardiomyogenic differentiation pathway, as indicated by expression of connexin 43 and troponin I in a fusion-independent manner. Some of the injected cells integrated with host cardiomyocytes through connexin 43, and others were incorporated into newly formed vessels. Human adipose tissue-derived stem cells survived in injured hearts up to 4 months, as detected by luciferase-based bioluminescence imaging. Vascular density was significantly increased, and fewer apoptotic cells were present in the peri-infarct region of cell-injected mice. This is the first study to systematically compare the effects of fhADCs and hASCs on myocardial regeneration. Both cell types engraft into infarcted myocardium, survive, and improve myocardial function, suggesting that fhADCs, like hASCs, are a promising alternative cell source for myocardial repair after MI.