A combined cell therapy and in-situ tissue-engineering approach for myocardial repair.

Myocardial cell-replacement strategies are hampered by limited sources for human cardiomyocytes and by significant cell loss following transplantation. We tested the hypothesis that a combined delivery of cardiomyocytes with an in-situ polymerizable hydrogel into a post-MI rat heart will result in better functional outcomes than each intervention alone. A photopolymerizable, biodegradable, PEGylated-fibrinogen (PF) hydrogel matrix was used as the carrier for the cardiomyocytes [neonatal rat ventricular cardiomyocytes (NRVCMs) or human embryonic stem cell-derived cardiomyocytes (hESC-CMs)]. Infarcted rat hearts (LAD ligation) were randomized to injection of saline, NRVCMs, biopolymer, or combined biopolymer-cell delivery. Echocardiography revealed typical post-infarction remodeling after 30 days in the saline-injected control group [deterioration of fractional shortening (FS) by 31.0 ± 3.6%]. Injection of NRVCMs or PF alone significantly (p < 0.01) altered this remodeling process (slightly increasing FS by 3.1 ± 6.6% and 0.5 ± 5.3% respectively). Co-injection of the NRVCMs with PF matrix resulted in a significant increase in the cell-graft area (by 144%) and in the highest improvements in FS (by 26.3 ± 6.6%). Finally, feasibility studies were performed with the PF matrix and hESC-CMs. We conclude that an injectable in-situ forming hydrogel can act as a cardiomyocyte cell-carrier and add to the beneficial effects of the grafted cells in preventing unfavorable post-infarction cardiac remodeling.