Autophagy and cardiocyte apoptosis after heterotopic transplantation of the mouse heart preserved in high-pressured mixed gas / 医学研究生学报

ABSTRACT

Objective Heart transplantation is an effective treatment of end-stage heart diseases and extending the time of donor heart preservation helps to make up for the shortage of donor hearts. This study was to investigate whether high-pressured mixed gas ( HPMG) of carbon monoxide and oxygen could prolong the time of donor heart preservation and its mechanisms. Methods Forty-eight C57BL/6 male mice aged 4-6 weeks were randomly divided in-to four groups of equal numbercontrol ( the donor heart isolated but not transplanted) , immediate transplantation ( the donor heart transplanted right after isolated) , HTK-preservation ( the donor heart preserved in histidine-tryptophan-ketoglutarate solution for 24 hours after isolated, and HPMG preservation ( the donor heart preserved in an HPMG chamber with the oxygen partial pressure of 3200 hPa and carbon monoxide partial pressure of 800 hPa for 24 hours after isolated) .Another 36 recipient mice aged 6-8 weeks were randomly assigned to receive the donor heart immediately after harvested (n=12), preserved in HTK solution (n=12), or preserved in HPMG (n=12).At 2 hours after transplantation, the status of heart re-beating and cardiac function were compared among different groups of recipient mice.At 24 hours, tissues were taken from the transplanted hearts for examination of pathologic changes by HE stai-ning, detection of the apoptosis of cardiac cells by TUNEL, and determination of the expressions of microtubule-associated protein 1 light chain 3 -Ⅱ(LC3-Ⅱ) and B cell lymphoma/leukemia-2 (Bcl-2) by Western blot. Resul ts The re-beating rates of the imme-diately transplanted and HPMG-preserved hearts were significantly higher than that of the HTK-preserved ones (P<0.05).At 2 hours after transplantation, the cardiac function scores were 2.5 (2.0-2.9), 0.8 (0.5-1.0), and 4.5 (4.0-4.5) in the immediate implantation, HPMG-preservation and HTK-preservation groups respectively, with statistically significant differences between any two groups (P<0.05).The expressions of LC3-Ⅱand Bcl-2 were 2.06 ±0.29 and 0.87 ±0.18 in the HPMG-preserved heart recipients and 1.24 ±0.20 and 2.07 ±0.32 in the immediately transplanted heart recipients, both higher than 0.13 ±0.03 and 0.19 ±0.02 in the controls and 0.16 ±0.06 and 0.26 ±0.08 in the HTK-preserved heart recipients (P<0.05), the Bcl-2 higher in the HTK-pre-served heart recipients than in the controls (P<0.05), and the LC3-Ⅱ expression higher in the HPMG-preserved heart recipients than in the immediately transplanted heart recipients (P<0.05).HE staining showed that cell edema and inflammatory cell infiltration were more obvious in the HPMG-preserved heart recipients than in the controls and immediately transplanted heart recipients but less obvious than in the HTK-preserved heart recipients.The rate of cell apoptosis was dramatically increased in the HPMG-and HTK-pre-served heart recipients ([5.04 ±1.77]%and [26.72 ±5.23]%) in comparison with the controls ([1.08 ±0.56]%) (P<0.01) and immediately transplanted heart recipients ([2.13 ±1.71]%) (P<0.01) but decreased in the HPMG as compared with the HTK-preserved heart recipients (P<0.01). Conclusion High-pressured mixed gas preservation can reduce cold ischemia-reperfu-sion injury of the donor heart, which may be associated with its promotion of autophagy, provision of energy to cells, and apoptosis of cardiocytes in the donor heart.