[Experimental study on umbilical vascular compliance and expression of antigen after removing endothelial cell].

Objective: To evaluate which is better method zymogen or low temperature frozen in removing vascular endothelial cell so as to lay a foundation for creating a kind of brace which is not to be rejected and the same as own blood vessel.

Methods: Fresh and not damaged umbilical blood vessel was collected from natural labour women, human umbilical blood vessel was remove carefully from normal foetus, then was put into disinfectant at 37 C for 24 hours. They were divided into 3 groups:normal group (NG), zymogen group (ZG) and low temperature frozen group (LG). ZG: 0.1% collagen II enzyme was added in umbilical blood vessel and closed the both sides and the vascular endothelial cell was removed in 37 C water. LG:Umbilical blood vessel was put into liquid nitrogen for 24 hours after frozened step by step, and then it was put into 37 C water for 30-60s and the vascular endothelial cells were washed away by normal saline. NG:Umbilical blood vessel was kept into 4 C Kerb's liquid. The bacteria were cultured in each group. The samples were stained by HE, elastic fiber and collagen fiber were observed by light and scanning electron microscope. The difference of compliance was compared. Human leukocyte antigen ABC (HLA-ABC) and HLA-DR were observed by immunohistochemical method and the expression of antigen of umbilical blood vessel was analysed. Results In LG, umbilical vascular endothelial cells were removed completely; artery showed vertical smooth muscle and vein showed elastic membrane. In ZG, umbilical vascular endothelial cells were removed completely after 20 minutes; artery showed vertical smooth muscle cells and vein showed lower endothelial layer. The vascular compliance in LG was higher than that in NG, and the latter was also higher than that in ZG, but showing no significant differences (P > 0.05). The compliance of umbilical vein was 2-3 times as much as that of umbilical artery. The expression of HLA-ABC and HLA-DR in LG and ZG were lower than that in NG, showing significant differences (P < 0.01).

Conclusion: Low temperature frozen method and zymogen method (0.1% collagen II enzyme for 20 min) can remove vascular endothelial cells of human umbilical blood vessel completely. Low temperature frozen method was better than zymogen method.