Fig 1: ApoEV treatment improves skin and hair follicle MSC functions. (A) Immunofluorescent images show that GFP-ApoEV (green) were engulfed by skin MSCs (SMSCs) (1 and 2), as indicated by co-staining with CD105 at 7 days post-injection. The right panel exhibits the higher magnification of the boxed region to show colocalization of GFP-ApoEV and CD105 positive SMSCs. (B) Western blotting shows GFP signals was detected in SMSCs after GFP-ApoEV injection. (C) Immunofluorescent staining of SMSC smears shows skin cells endocytosed apoEVs. (D) Western blotting shows Wnt/ß-catenin signaling is activated and DKK1 expression is decreased in SMSCs and hair follicle MSCs (HF-MSCs) from MRL/lpr mice after apoEVs injection. (E, F, I and J) EdU and population doubling assay show that MRL/lpr SMSCs and HF-MSCs had reduced proliferation and passage rates when compared to the wild-type control group. After apoEV treatment, proliferation and passage rates were improved in MRL/lpr SMSCs and HF-MSCs, respectively. n = 3–5. *P < 0.05, **P < 0.01, ***P < 0.001, one-way ANOVA test. Data shown as mean ± SD. (G, K) Compared to wild-type SMSCs, MRL/lpr SMSCs showed reduced capacity to form mineralized nodules when cultured under osteogenic inductive conditions, assessed by alizarin red staining, and reduced expression of osteogenic markers Runx2 and ALP, assessed by Western blotting. After apoEV treatment, reduced mineralized nodule formation and expression of Runx2 and ALP were rescued in MRL/lpr SMSCs (G). The osteogenic capacity of MRL/lpr HF-MSCs was also rescued after apoEV treatment (K). n = 3. ***P < 0.001, one-way ANOVA test. Data shown as mean ± SD. (H, L) Compared to wild-type SMSCs, MRL/lpr SMSCs showed reduced capacity to differentiate into adipocytes when cultured under adipogenic inductive conditions, as assessed by Oil red O staining, along with reduced expression of adipogenic markers PPAR? and LPL, as assessed by Western blotting. After apoEV treatment, reduced adipocyte formation and expression of PPAR? and LPL were rescued in MRL/lpr SMSCs (H). The adipogenic capacity of MRL/lpr HF-MSCs was also rescued after apoEV treatment (L). n = 3. *P < 0.05, **P < 0.01, ***P < 0.001, one-way ANOVA test. Data shown as mean ± SD. Scale bars (A, C), 50 µm.