Exosomes derived from ADSCs suppress the fibrosis process of derma in secondary lymphedema.

Secondary lymphedema (SLE), a progressive condition characterized by limb swelling and tissue fibrosis, frequently arises following oncologic surgery or radiotherapy. Fibrosis in SLE is primarily mediated through the TGFβ-Smad signaling pathway. Adipose derived multipotent mesenchymal stromal cells (ADSCs) and their secreted extracellular vesicles, known as exosomes (ADSC-Exs), have shown therapeutic potential in alleviating SLE. While both ADSCs and ADSC-Exs exhibit anti-fibrotic effects, the extent to which these benefits are attributable to modulation of the TGFβ-Smad pathway remains unclear. EW-7197, a known inhibitor of TGFβ1 signaling, also attenuates fibrosis by suppressing this pathway. However, a direct comparison among ADSCs, ADSC-Exs, and EW-7197 in the context of SLE has not been conducted. This study aims to elucidate the mechanisms by which ADSCs and ADSC-Exs mitigate fibrosis through regulation of the TGFβ-Smad pathway and, for the first time, compares the therapeutic efficacy of ADSCs, ADSC-Exs, and EW-7197 in a model of secondary lymphedema. We established a secondary lymphedema model in C57BL/6 mice through surgical excision and localized radiation. Tissue staining was used to assess fibrosis progression at key time points, identifying the peak fibrosis stage. ADSCs and ADSC-Exs were injected into the affected areas to test their therapeutic effects, while TGFβ1 inhibitors were used as controls to block the TGFβ-Smad signaling pathway. This study compared the effects of ADSCs, ADSC-Exs, and the inhibitors on lymphedema and fibrosis markers, with a focus on their influence on the TGFβ-Smad pathway. Fibrosis in the SLE model peaked between the 4th and 5th weeks. Both ADSCs, ADSC-Exs, and the TGFβ inhibitor EW-7197 reduced edema and fibrosis, with ADSC-Exs having the most significant effect on skin fibrosis. This was evident by decreased levels of TGFβ1, Smad2/3, and phosphorylated Smad2/3, along with increased Smad7 levels, indicating that ADSC-Exs effectively regulate the TGFβ-Smad pathway to reduce fibrosis. Our findings demonstrate that ADSCs and ADSC-Exs significantly alleviate edema and fibrosis in a secondary lymphedema mouse model. This therapeutic effect is largely mediated through the regulation of the TGFβ-Smad pathway, suggesting a promising approach for treating fibrosis in SLE.