Hydrogel based injectable scaffolds for cardiac tissue regeneration.
BACKGROUND Growing evidence suggests that intramyocardial biomaterial injection improves cardiac functions after myocardial infarction (MI) in rodents. Cell therapy is another promising approach to treat MI, although poor retention of transplanted cells is a major challenge. In this study, we hypothesized that intramyocardial injection of self-assembling peptide nanofibers (NFs) thickens the infarcted myocardium and increases transplanted autologous bone marrow mononuclear cell (MNC) retention to attenuate cardiac remodeling and dysfunction in a pig MI model. METHODS AND RESULTS A total of 40 mature minipigs were divided into 5 groups: sham, MI+normal saline, MI+NFs, MI+MNCs, and MI+MNCs/NFs. MI was induced by coronary occlusion followed by intramyocardial injection of 2 mL normal saline or 1% NFs with or without 1×10(8) isolated autologous MNCs. NF injection significantly improved diastolic function and reduced ventricular remodeling 28 days after treatment. Injection of MNCs alone ameliorated systolic function only, whereas injection of MNCs with NFs significantly improved both systolic and diastolic functions as indicated by +dP/dt and -dP/dt (1214.5±91.9 and -1109.7±91.2 mm Hg/s in MI+NS, 1693.7±84.7 and -1809.6±264.3 mm Hg/s in MI+MNCs/NFs, respectively), increased transplanted cell retention (29.3±4.5 cells/mm(2) in MI+MNCs and 229.4±41.4 cells/mm(2) in MI+MNCs/NFs) and promoted capillary density in the peri-infarct area. CONCLUSIONS We demonstrated that NF injection alone prevents ventricular remodeling, whereas cell implantation with NFs improves cell retention and cardiac functions after MI in pigs. This unprecedented combined treatment in a large animal model has therapeutic effects, which can be translated to clinical applications in the foreseeable future.