Extracellular vesicles derived from human adipose-derived stem cells promote the exogenous angiogenesis of fat grafts via the let-7/AGO1/VEGF signalling pathway

Abstract

Extracellular vesicles (EVs) derived from human adipose-derived stem cells (hADSCs) possess the proangiogenic potential for ischaemic diseases. Thus, our study aimed to evaluate the therapeutic effects of hADSC-EVs on fat grafting and explore the mechanism of hADSC-EVs promoting angiogenesis. The EVs released by hADSCs incubated under normal or hypoxic conditions were employed to supplement fat grafting in a nude mouse model. The proliferation, migration, tube formation and vascular endothelial growth factor (VEGF) secretion of vascular endothelial cells cocultured with two kinds of hADSC-EVs were analysed. MicroRNA sequencing was performed to reveal the species and content of microRNAs in hADSC-EVs, the key microRNAs were blocked, and their effect in promoting angiogenesis was detected via above protocols as a reverse proof. The results demonstrate that hADSC-EVs could improve the survival of fat grafts by promoting exogenous angiogenesis and enhance the proliferation, migration, tube formation and VEGF secretion of vascular endothelial cells. In addition, the pro-angiogenic effect of hADSC-EVs in vivo and vitro could be enhanced by hypoxic pretreatment. We found that the let-7 family, a kind of hypoxic-related microRNA, is enriched in hypoxic hADSC-EVs that contribute to angiogenesis via the let-7/argonaute 1 (AGO1)/VEGF signalling pathway.Fat grafting has been widely used for soft tissue filling in cosmetic plastic surgery (such as breast augmentation and facial rejuvenation) and reconstruction surgery due to several diseases (such as soft tissue defects caused by facial muscle atrophy, tumour excision and breast reconstruction after breast cancer surgery) 1 . The technology of fat grafting has made significant advances in the past decades, being considered less technically challenging because of the sophisticated liposuction technique, low donor site morbidity after transplantation and reduced host immune responses 1-3 . However, the main limitation is the necrosis and absorption of grafts due to poor revascularization 4,5 . Therefore, the survival of fat grafts can still be improved.The process of liposuction and injection leads to devascularisation and ischaemic injury of the adipose tissue. Since the adipose tissue is less tolerant to ischaemia 3 , early revascularization of the transplanted tissue is critical for the survival of fat grafts 4 . Various studies have demonstrated the promotion of angiogenesis by mesenchymal stem/stromal cells (MSCs). Yoshimura et al. 6 developed a cell-assisted lipotransfer (CAL) strategy to co-transplant autologous adipose tissue with adipose stromal cells. The meta-analysis performed by Laloze et al. 7 demonstrated that the CAL technology can significantly improve survival from 44 to 64%. With the progress on the research of the biological functions of MSCs, for fat grafting, the paracrine effect of adipose-derived stem cells (ADSCs) play important roles in angiogenesis and tissue regeneration 8 . In addition, studies in recent years have www.nature.com/scientificreports...

Electrospun Nanofibers for Improved Angiogenesis: Promises for Tissue Engineering Applications

“…Regarding the outcome of numerous experimental studies, it can be stated that extracellular vesicles and exosomes containing pro-angiogenic growth factors are responsible elements for improving neovascularization [196][197][198][199]. For instance, extracellular vesicles released from human adipose-derived stem cells have been shown to promote angiogenesis through the let-7/AGO1/VEGF signaling pathway in an ischemic model of mice [198]. Despite this potent pro-angiogenic capacity, there is limited evidence of experiments in which pro-angiogenic exosomes and vesicles incorporated into the nanofibrous mats were shown to induce neovascularization.…”

“…Endothelial progenitor cells, endothelial cells, mural cells like pericytes and smooth muscle cells, mesenchymal stem cells, and hematopoietic stem cells are among the most promising candidates for promoting angiogenesis as they are able to secrete pro-angiogenic growth factors and cytokines [ 192 , 193 , 194 , 195 ]. Regarding the outcome of numerous experimental studies, it can be stated that extracellular vesicles and exosomes containing pro-angiogenic growth factors are responsible elements for improving neovascularization [ 196 , 197 , 198 , 199 ]. For instance, extracellular vesicles released from human adipose-derived stem cells have been shown to promote angiogenesis through the let-7/AGO1/VEGF signaling pathway in an ischemic model of mice [ 198 ].…”

Extracellular vesicles‐encapsulated let‐7i shed from bone mesenchymal stem cells suppress lung cancer via KDM3A/DCLK1/FXYD3 axis

“…Furthermore, the low expression of let‐7 in lung cancer has been linked with the poor prognosis of lung cancer patients 37 . Moreover, let‐7 has been found to be highly expressed miRNA in EVs derived from human adipose tissue stem cells 38,39 . Lung cancers were then treated with BMSC‐EV‐let‐7i‐mimic to further explore the effect of let‐7i in BMSC‐EVs on lung cancer, the results of which showed significant suppression of proliferation, migration and invasion of lung cancer cells.…”

Extracellular Vesicles in Musculoskeletal Pathologies and Regeneration

“…They have been reported to exert pro- or antiangiogenic effects (Todorova et al, 2017 ) that have been related to various signaling pathways, which may be targeted by the corresponding ligands and cytokines contained in EVs, such as: vascular endothelial growth factor (VEGF) (Brill et al, 2005 ; Zou et al, 2016 ; Gangadaran et al, 2017 , 2020 ; Ahn et al, 2018 ; Tang et al, 2019 ), platelet-derived growth factor (PDGF) (Brill et al, 2005 ; Ma et al, 2017 ) and MMPs (Taraboletti et al, 2002 ; Han et al, 2019 ; Tang et al, 2019 ). Moreover, a number of miRNAs involved in angiogenic effects of EVs have been identified, e.g., pro-angiogenic miR31, miR-125a, miR-126, miR-130a, miR-150, miR-210, miR214 (Li et al, 2013 ; van Balkom et al, 2013 ; Kang et al, 2016 ; Liang et al, 2016 ; Lombardo et al, 2016 ; Du et al, 2017a ; Gong et al, 2017a ; Wu et al, 2018 ; Jia et al, 2019 ; Nie et al, 2019 ; Gangadaran et al, 2020 ; Zhu et al, 2020 ).…”

“…This knowledge can be used to optimize EV-based therapeutic approaches, for example, with respect to promoting their angiogenic effects. Next to pro-angiogenic impact induced by hypoxic preconditioning (Xue et al, 2018 ; Han et al, 2019 ; Zhu et al, 2020 ), it has been demonstrated that nitric oxide (NO) stimulation could augment the pro-angiogenic effects of placenta-derived MSCs, which was attributed to increased levels of miR-126 and VEGF (Du et al, 2017a ). Similarly, PDGF stimulation promotes the pro-angiogenic efficacy of adipose tissue MSC-EVs (Lopatina et al, 2014 ).…”