Supplementary Material for: Effect of youthful blood environment and its key factor SCF on renal interstitial fibrosis in elderly mice

Introduction: Youthful blood environment was shown to decelerate the aging process of kidney and to attenuate senile renal fibrosis in a young-old parabiotic animal model; in addition, we identified a stem cell factor (SCF) that is closely linked with the process. This research was to investigate the effect of youthful blood environment on senile renal interstitial fibrosis and the role of SCF. Methods: We bred SCF receptor c-Kit gene loss-of-function Wps/Wps mice and established a combination mice model that was subjected to unilateral ureteral obstructive (UUO) and parabiotic surgeries. Parabiotic mice were divided into isochronic parabiotic (young-young, Y-IP and old-old, O-IP) and heterochronic parabiotic (young-old, HP) groups. UUO surgery was performed in one of the parabiotic pairs in the IP group (Y-IPuuo and O-IPuuo) and in the elderly mice in the HP group (O-HPuuo). In order to study the role of SCF/c-kit on renal interstitial fibrosis, UUO surgery was performed in wildtype (WT) and Wps/Wps mice. Results: Fourteen days after UUO surgery, the kidney interstitial fibrosis area, kidney function, and the expressions of SCF/c-Kit, pNF-κB, and fibrosis-related proteins in the O-HPuuo group were significantly lower than those in the Ouuo and O-IPuuo groups. Compared with wildtype UUO mice, the expressions of pNF-κB and fibrosis-related proteins, and the kidney function were all significantly decreased in Wps/Wps UUO mice. Conclusion: Youthful blood environment downregulated the expressions of SCF/c-Kit in elderly UUO mice, and ameliorated UUO-induced kidney fibrosis and function loss.