Experimental Study on the In-Vivo Heterotopic Transplantation of Aortic Valved Homografts after De-Endothelialization

Background and aim of the study: The study aims were to monitor the changes in tissue morphology, calcium content and CD40 expression in the in-vivo heterotopic transplantation of aortic valved homografts after de-endothelialization, and to seek better methods for preventing calcification and degeneration of the homograft valves.

Methods: Adult, healthy, inbred male Chinese rabbits were used as donors, and inbred adult female New Zealand White rabbits as recipients for the heterotopic transplantation of aortic valved homografts with abdominal aorta. Controls received aortic valved homografts without treatment, while the de-endothelialization group received aortic valved homografts after de-endothelialization. For the cryopreservation group, aortic valved homografts were treated with 10% dimethyl sulfoxide and cryopreserved in liquid nitrogen for 60 days. Recipients were randomly allocated to three groups (n = 20 per group). Grafts were removed after two, four, eight and 12 weeks of surgery and observed with light microscopy. Calcium

concentrations were monitored using flame atomic absorption, and CD40 expressions with immunohistochemistry.

Results: At two weeks after transplantation, the calcium contents of the fresh, de-endothelialization and cryopreservation groups were similar (p >0.05). The calcium content at four, eight and 12 weeks in the fresh and cryopreservation groups was significantly higher than that in the de-endothelialization group (p <0.01), while at two, four and eight weeks after transplantation, CD40 expression in the fresh and cryopreservation groups was significantly different from that in the de-endothelialization group (p <0.01).

Conclusion: The calcium content in valve homografts was found to correlate with immune rejection. De-endothelialization could reduce immune rejection reactions and prevent calcification of aortic homograft valve.