Comparison of two cell-free therapeutics derived from adipose tissue: small extracellular vesicles versus conditioned medium

Abstract

Background Cell-free therapy has been inspired as a promising approach to overcome the limitations of traditional stem cell therapy. However, the therapeutic effect between extracellular vesicles and conditioned medium with the same source had not been compared. Our previous studies have shown that both the conditioned medium of adipose tissue (adipose tissue extract, ATE) and its further purification product small extracellular vesicles (sEV-AT) contributed to adipose tissue regeneration. In this study, we aimed to compare the ATE and sEV-AT in composition, inductivity on cells and de novo adipose regenerative potential. Methods The characteristics of sEV-AT and ATE were compared through protein and particle yield, particle size distribution and composition. The inductivity of sEV-AT and ATE on cells were compared through co-culture of sEV-AT or ATE with ASC, HUVEC and RAW264.7 in vitro. The capacity of promoting de novo adipogenesis was compared by implanting the silicone tube containing sEV-AT or ATE subcutaneously in vivo. Results More particles and concentrated particle size distribution were detected in sEV-AT. In turn, more soluble factors and multiple peaks in particle size distribution were detected in ATE. In 1662 common proteins of sEV-AT and ATE, there were 984 (59.2%) proteins enriched twice more in sEV-AT than in ATE. With the prerequisite of equivalent protein concentration, sEV-AT outperformed ATE in promoting proliferation, migration and regeneration potential of cells those contributing adipose tissue regeneration in vitro. Furthermore, sEV-AT expedited the de novo adipose tissue regeneration and angiogenesis at the early stage than ATE in vivo, but sEV-AT and ATE group formed similar neoadipose tissue and new vessels at week 12. Conclusions Our results provided a direct comparison between EV and conditioned medium as cell-free therapeutic strategy. Both sEV and ATE had specific biological signature to facilitate tissue repair. Considering the convenience of extraction and acceptable effect, ATE represented a feasible product of cell-free therapy, providing another option for different situations in clinical application. Furthermore, the complex contents of both sEV-AT and ATE should be studied comprehensively to avoid possible negative effects and to ensure sufficient safety for clinical applications.

Adipose tissue-derived small extracellular vesicles modulate macrophages to improve the homing of adipocyte precursors and endothelial cells in adipose tissue regeneration

“…In the past few years, we found sEV-AT could effectively induce adipose tissue regeneration ( Dai et al, 2017 ) and adipose tissue extract (ATE) also showed the same ability ( He et al, 2022 ). We also found the ability of sEV-AT derived from rats and porcine to repair soft tissue was similar.…”

“…For tissue regeneration, sEVs have been reported to recruit host cells, regulate immune responses, stimulate angiogenesis, and promote tissue repair or regeneration ( Qi et al, 2016 ; Zhang et al, 2016 ; Ahn et al, 2018 ). Our previous study has shown that adipose tissue-derived small extracellular vesicles (sEV-AT), possessed the typical characteristics of sEVs, could effectively promote adipose tissue regeneration ( Dai et al, 2017 ; Dong et al, 2020 ; He et al, 2022 ). However, the interaction between sEV-AT and the host’s immune system, especially macrophages, was unknown.…”

Human adipose tissue-derived small extracellular vesicles promote soft tissue repair through modulating M1-to-M2 polarization of macrophages

“…The particle size and size distribution of h-sEV-AT were determined by Zeta View analysis system (Particle Metrix, Germany) according to the manufacturer's protocol. The marker proteins were detected by Western blot according to our previous methods [13,16]. Briefly, 30 μg h-sEV-AT mixed with loading buffer (Solarbio, China), boiled for 10 min, resolved on 10% polyacrylamide gel, and blotted onto a nitrocellulose membrane.…”

“…Our previous study has shown that rat and porcine adipose tissue-derived small extracellular vesicles effectively promoted soft tissue regeneration [13][14][15][16]. However, whether small extracellular vesicles could be isolated from human liposuction adipose tissue and whether it also showed effectiveness on soft tissue were unknown.…”

Cell-Free Fat Extract Improves Ovarian Function and Fertility in Mice With Advanced Age

“…Adipose tissue, which is rich in cytokines, has been processed and applied in various diseases ( 22 , 23 ). Cell-free fat extract (CEFFE) is a cell-free liquid with active protein components acquired from adipose tissues via the process of mechanical emulsification and centrifugation to remove cellular debris and viable cell components and sterilization, which has advantages of an autogenous source, low immunogenicity, no tumorigenicity, high clinical safety, and low ethical risk.…”