Abstract P393: Fabrication Of Immunomodulatory Hydrogels For Cardiac Repair After Acute Myocardial Infaction

Abstract

Introduction: The balance of pro- and anti-inflammatory processes is tightly linked to left ventricular remodeling after myocardial infarction. Immune activation also plays a key role in rejection of transplanted allogeneic stem cells. In this study, we present the design, fabrication and characterization of immunomodulatory chitosan-based hydrogels for cardiac repair after myocardial infarction. Methods: Chitosan hydrogels conjugated with small immunomodulatory molecules were synthesized through a thermogelation process. Resultant hydrogels were characterized using scanning electron microscopy and Fourier-transformed infrared spectroscopy. Human mesenchymal stem cells were encapsulated into the hydrogels and biocompatibility was assessed after one week using fluorescence microscopy and a colorimetric assay. Immunomodulatory activity was assessed after co-culture with human T-lymphocytes using flow cytometry for CD4+IFN-γ+ pro-inflammatory and CD4+CD25+FoxP3+ regulatory T-lymphocytes. Results: Small immunomodulatory molecules were successfully integrated into chitosan hydrogels. Physico-chemical characterization revealed no significant changes to the 3D structure and porosity of hydrogels. The addition of 10μM atorvastatin or 10μM rosuvastatin did not result in significant cytotoxicity to encapsulated mesenchymal stem cells at 3 or 7 days. Addition of statins resulted in marked suppression of CD4+ T-lymphocyte proliferation (Control 25.1 Fold, Atorvastatin 1.0 Fold, Rosuvastatin 2.3 Fold, p<0.001) and activation (CD4+IFN-γ+ Population: Control 87.1%, Rosuvastatin 23.7%, p<0.001) after stimulation. No differences were seen in percentages of CD4+CD25+FoxP3+ regulatory T-lymphocytes (Control 5.5%, Rosuvastatin 5.7%, ns). Conclusion: A biocompatible immunomodulatory hydrogel was created through integration of atorvastatin and rosuvastatin into a chitosan hydrogel. Experiments are currently underway in vivo to examine its usefulness for stem cell delivery and reducing adverse left ventricular remodeling after myocardial infarction.