The effects of cryopreservation on the immunogenicity of HUVEC

Abstract

Objective To study the effects of cryopreservation on the immunogenicity of human umbilical vein endothelial cells(HUVEC).Methods HUVEC were isolated ex vivo and cryopreserved.Lymphocyte stimulation index(SI)was analyzed by MTT in lymphoeyte-endothelial cell co-culture.Both HLA-ABC and HLA-DR antigen expression on fresh or cryopreserved HUVEC,and the effects of IFN-γ treatment on HLA antigen expression in both groups were determined by using flow cytometry.Results No difference in SI was observed between fresh prepared and cryopreserved HUVEC(1.716±0.181 vs 1.686±0.145,P>0.05).The percentage of HLA-ABC expression was(96.6±1.9)%and(96.0±1.4)%in fresh and cryopreserved HUVEC(P>0.05),and the mean intensity for HLA-ABC expression was 84.1±5.7 and 82.4±4.8 in fresh and cryopreserved HUVEC(P>0.05),respectively.However,no HLA-DR expression was observed in both groups.When treated with IFN-γ,HLA-ABC expression was significantly up-regulated,and HLA-DR expression was induced in a dose-dependent manner.No significant difference was found in the HLA-ABC expression between fresh and cryopreserved HUVEC(P>0.05),while the HLA-DR expression in cryopreserved HUVEC was remarkably lower than in fresh HUVEC with the increase of IFN-γ(P<0.01).Conclusion The immunogenicity of HUVEC remains stable by cryopreservation without IFN-γtreatment or treated with low concentration of IFN-γ(≤50 U/ml).However,the HLA-DR expression in HUVEC was remarkably reduced in eryopreserved cells treated with a high concentration of IFN-γ(≥100 U/ml).These data indieated that the effects of cryopreservation on immunogenicity of HUVEC may result from the decreased responses of HLA-DR expression by the stimulation of IFN-γ treatment. Key words: Endothelial cells; Umbilical veins; HLA antigens; Humans; Cryopreservation