Gelatin microspheres encapsulated with a nonpeptide angiogenic agent, ginsenoside Rg1, for intramyocardial injection in a rat model with infarcted myocardium

Angiogenic therapies may need to select a stable agent to be delivered. In the study, a nonpeptide angiogenic agent, ginsenoside Rg1 (Rg1), was encapsulated in the gelatin microspheres (MSs) crosslinked with genipin and intramuscularly injected into a rat model with infarcted myocardium. bFGF was used as a control. After swelling in an aqueous environment, the MSs without crosslinking became collapsed and stuck together. For those crosslinked, the swollen MSs appeared to be more stable with an increasing the degree of crosslinking. After it was released from MSs in vitro, the remaining activity of bFGF on HUVEC proliferation reduced significantly, while that of Rg1 remained constant. An inspection of the retrieved hearts revealed a large aneurysmal left ventricle (LV) with a thinned myocardium and a significant myocardial fibrosis for that treated with the Empty MSs (without drug encapsulation). However, those receiving the MSs encapsulated with bFGF or Rg1 attenuated the enlargement of the LV cavity and the development of myocardial fibrosis. The densities of microvessels found in the border zones of the infarct treated with the bFGF or Rg1 MSs were significantly greater than that treated with the Empty MSs. These results indicated that Rg1, a stable angiogenic agent, successfully enhanced the myocardial perfusion and preserved the infarcted LV function.