Transplantation of adipose tissue mesenchymal cells conjugated with VEGF-releasing microcarriers promotes repair in murine myocardial infarction

RATIONALE: Engraftment and survival of transplanted stem or stromal cells in the microenvironment of host tissues may be improved by combining such cells with scaffolds to delay apoptosis and enhance regenerative properties. OBJECTIVES: We examined whether poly(lactic-co-glycolic acid) (PLGA) pharmacologically active microcarriers (PAMs) releasing vascular endothelial growth factor (VEGF) enhance survival, differentiation and angiogenesis of adipose tissue-mesenchymal stromal cells (AT-MSCs). We analyzed the efficacy of transplanted AT-MSCs conjugated with PAMs in a murine model of acute myocardial infarction (AMI). METHODS: We used fibronectin-coated (empty) PAMs or VEGF-releasing PAMs covered with murine AT-MSCs. Twelve month-old C57 mice underwent coronary artery ligation (Lig) to induce AMI, and were randomized into 5 treatment groups: AMI control (saline 20 µL, n=7), AMI followed by intramyocardial injection with AT-MSCs (2.5x105 cells/20 µL, n=5), or concentrated medium from AT-MSCs (CM, 20 µL, n=8), or AT-MSCs (2.5x105 cells/20 µL) conjugated with empty PAMs (n=7), or VEGF-releasing PAMs (n=8). Sham-operated mice (n=7) were used as controls. RESULTS: VEGF-releasing PAMs increased proliferation and angiogenic potential of AT-MSCs, but did not impact their osteogenic or adipogenic differentiation. AT-MSCs conjugated with VEGF-releasing PAMs inhibited apoptosis, decreased fibrosis, increased arteriogenesis and the number of cardiac-resident Ki-67 positive cells, and improved myocardial fractional shortening compared with AT-MSCs alone when transplanted into the infarcted hearts of C57 mice. With the exception of fractional shortening, all such effects of AT-MSCs conjugated with VEGF-PAMs were paralleled by the injection of CM. CONCLUSIONS: AT-MSCs conjugated with VEGF-releasing PAMs exert paracrine effects that may have therapeutic applications.