Resistance of rat adipose-derived stem cells to human xenoantibody-dependant complement-mediated lysis and its mechanism / 中华器官移植杂志

ABSTRACT

Objective To investigate whether rat adipose-derived stem cells (rASCs) could resist human xenoantibody-dependent complement-mediated lysis and to explore its possible mechanisms.Method SD rat ASCs were isolated,rASCs at passage 2 to 8 were used for the following studies and rat lymphocytes were harvested as control cells.α-Gal expression was detected by flow cytometry.After incubation of rASCs with 20％ normal human serum (NHS) or heat inactivated normal human serum (HINHS),flow cytometry was used to detect cytotoxicity,IgG or IgM binding,and C3c,C4c and C5b-9 deposition.Result We successfully established the method to isolate and culture rASCs.The morphology of rASCs remained unchanged after passages.rASCs were positive for tell surface markers of CD44 and CD90,while negative for CD45 and MHC-Ⅱ.As compared with rLCs,rASCs significantly resisted human natural antibody and complement-mediated lysis when incubated with 20％ NHS in vitro (20.42％ ± 2.80％ vs 51.84％ ± 6.70％,P ＜ 0.01).Mechanistically,rASCs expressed lower level of α-Gal (13.97 ± 0.33 vs.24.47 ± 3.03,P＜0.05),which was correlated with decreased binding of human xenoreactive IgG and IgM (IgM9.4 ± 2.0 vs.107.2± 4.8,P＜0.01; IgG5.73 ± 1.0 vs.27.49 ± 3.9,P＜0.01) and reduced deposition of complements C3c,C4c and C5b-9 (C3c294.6 ± 38.02 vs.1924 ± 509.4,P＜0.05; C4c35.23 ± 3.1vs.177.3 ± 37.17,P＜0.05; C5b-95.63 ± 1.74 vs.37.05 ± 7.4,P＜0.01).Conclusion These data demonstrated that the resistance of rASCs to human xenoantibody and complement-mediated lysis is associated with low expression of xenoantigen a-Gal and inhibition of MAC (membrane attack complex) formation.