OBJECTIVETo investigate whether injectable engineering heart tissue (EHT) can survive and improve heart function after transplantation into infarct area.

METHODSVentricular cardiomyocytes from 1-3 day-old Sprague-Dawley (SD) rats were isolated by using trypsin method, and then labeled and cultured. The left coronary of female SD rats was ligated to create a myocardial infarct model. Three weeks later, the qualified animals were randomized into four groups: EHT group (n = 12), which were transplanted with both cardiomyocytes and matrix; cell transplantation group (n = 12); matrix group (n = 12), control (n = 11). Four weeks after implantation, echocardiography and Langendorff model were used to assess heart function, and then the hearts were harvested for pathological examination. Meanwhile polymerase chain reaction (PCR) was performed to detect SRY gene on Y chromosome.

RESULTSThe grafted cells were identified in both EHT and cell transplantation group by either pathology or PCR. But in EHT group, transplanted cells formed more condensed tissue, and produced definite connected protein. Data of fraction shortness from echocardiography are showed as follows: EHT group, (22.82 +/- 3.44)%; cell transplantation group, (20.55 +/- 4.11)%, matrix group, (17.05 +/- 4.57)%; control, (19.80 +/- 3.98)% (P = 0.012). Langendorff examination revealed significant differences among four groups when left ventricular balloon volume was at the level of 0.06 ml, 0.08 ml and 0.10 ml, in which EHT group had the highest developed pressure and dp/dt.

CONCLUSIONIt is feasible to fabricate injectable EHT in vitro. The fabricated EHT could survive in the myocardial infarct area after transplantation in a rat model and improve heart function due to better histological configuration.