Abstract
Background
Autologous fat grafting is becoming increasingly common worldly. However, the long-term retention of fat grafting is still unpredictable due to the inevitable fibrosis that arises during tissue repair. Fibrosis may be regulated by T-cell immune responses that are influenced by adipose-derived stem cells (ASCs). Accordingly, we hypothesized that overly abundant ASCs might promote fibrosis by promoting T-cell immune responses to adipose tissue.
Methods
We performed 0.3 ml fat grafts with 104/ml, 106/ml and 108/ml ASCs and control group in C57 BL/6 mice in vivo. We observed retention, fibrosis, T-cell immunity, and macrophage infiltration over 12 weeks. In addition, CD4 + T-helper 1 (Th1) cells and T-helper 2 (Th2) cells were co-cultured with ASCs or ASCs conditioned media (CM) in vitro. We detected the ratio of Th2%/Th1% after 24 and 48 hours.
Results
In vivo, the retention rate was higher in the 104 group, while even lower in the 108 group with significantly increased inflammation and fibrosis than the control group at week 12. There was no significance between control group and the 106 group. Also, the 108 group increased infiltration of M2 macrophages, CD4 + T-cells and Th2/Th1 ratio. In vitro, the ratio of Th2%/Th1% induced by the ASCs-transwell group was higher than the ASCs-CM group and showed concentration-dependent.
Conclusions
High concentrations of ASCs in adipose tissue can promote Th1–Th2 shifting, and the excess of Th2 cells might promote the persistence of M2 macrophages and increase the level of fibrosis which lead to a decrease in the long-term retention of fat grafts. In addition, we found that ASCs promoted Th1–Th2 shifting in vitro.
Low antigen-specific CD4 T-cell immune responses despite normal absolute CD4 counts after long-term antiretroviral therapy an African cohort
