Unraveling the differential mechanisms of revascularization promoted by MSCs & ECFCs from adipose tissue or umbilical cord in a murine model of critical limb-threatening ischemia

BACKGROUND

Critical limb-threatening ischemia (CLTI) constitutes the most severe manifestation of peripheral artery disease, usually induced by atherosclerosis. CLTI patients suffer from high risk of amputation of the lower extremities and elevated mortality rates, while they have low options for surgical revascularization due to associated comorbidities. Alternatively, cell-based therapeutic strategies represent an effective and safe approach to promote revascularization. However, the variability seen in several factors such as cell combinations or doses applied, have limited their success in clinical trials, being necessary to reach a consensus regarding the optimal "cellular-cocktail" prior further application into the clinic. To achieve so, it is essential to understand the mechanisms by which these cells exert their regenerative properties. Herein, we have evaluated, for the first time, the regenerative and vasculogenic potential of a combination of endothelial colony forming cells (ECFCs) and mesenchymal stem cells (MSCs) isolated from adipose-tissue (AT), compared with ECFCs from umbilical cord blood (CB-ECFCs) and AT-MSCs, in a murine model of CLTI.

METHODS

Balb-c nude mice (n:32) were distributed in four different groups (n:8/group): control shams, and ischemic mice (after femoral ligation) that received 50 µl of physiological serum alone or a cellular combination of AT-MSCs with either CB-ECFCs or AT-ECFCs. Follow-up of blood flow reperfusion and ischemic symptoms was carried out for 21 days, when mice were sacrificed to evaluate vascular density formation. Moreover, the long-term molecular changes in response to CLTI and both cell combinations were analyzed in a proteomic quantitative approach.

RESULTS

AT-MSCs with either AT- or CB-ECFCs, promoted a significant recovery of blood flow in CLTI mice 21 days post-ischemia. Besides, they modulated the inflammatory and necrotic related processes, although the CB group presented the slowest ischemic progression along the assay. Moreover, many proteins involved in the repairing mechanisms promoted by cell treatments were identified.

CONCLUSIONS

The combination of AT-MSCs with AT-ECFCs or with CB-ECFCs promoted similar revascularization in CLTI mice, by restoring blood flow levels, together with the modulation of the inflammatory and necrotic processes, and reduction of muscle damage. The protein changes identified are representative of the molecular mechanisms involved in ECFCs and MSCs-induced revascularization (immune response, vascular repair, muscle regeneration, etc.).

Endoscopically injectable and self-crosslinkable hydrogel-mediated stem cell transplantation for alleviating esophageal stricture after endoscopic submucosal dissection

Esophageal stricture after extensive endoscopic submucosal dissection impairs the quality of life of patients with superficial esophageal carcinoma. Beyond the limitations of conventional treatments including endoscopic balloon dilatation and the application of oral/topical corticosteroids, several cell therapies have been recently attempted. However, such methods are still limited in clinical situations and existing setups, and the efficacies are less in some cases since the transplanted cells hardly remain at the resection site for a long time due to swallowing and peristalsis of the esophagus. Thus, a cell transplantation platform directly applicable with clinically established equipment and enabling stable retention of transplanted cells can be a promising therapeutic option for better clinical outcomes. Inspired by ascidians that rapidly self-regenerate, this study demonstrates endoscopically injectable and self-crosslinkable hyaluronate that allows both endoscopic injection in a liquid state and self-crosslinking as an in situ-forming scaffold for stem cell therapy. The pre-gel solution may compatibly be applied with endoscopic tubes and needles of small diameters, based on the improved injectability compared to the previously reported endoscopically injectable hydrogel system. The hydrogel can be formed via self-crosslinking under in vivo oxidative environment, while also exhibiting superior biocompatibility. Finally, the mixture containing adipose-derived stem cells and the hydrogel can significantly alleviate esophageal stricture after endoscopic submucosal dissection (75% of circumference, 5 cm in length) in a porcine model through paracrine effects of the stem cell in the hydrogel, which modulate regenerative processes. The stricture rates on Day 21 were 79.5% ± 2.0%, 62.8% ± 1.7%, and 37.9% ± 2.9% in the control, stem cell only, and stem cell-hydrogel groups, respectively (p < 0.05). Therefore, this endoscopically injectable hydrogel-based therapeutic cell delivery system can serve as a promising platform for cell therapies in various clinically relevant situations.

Comparative study of mouse adipose- and bone marrow mesenchymal stem cells in diabetic model with critical limb ischemia

The aim of this research is to compare the capabilities of Adipose tissue mesenchymal stem cells (AT-MSCs) and bone marrow mesenchymal stem cells (BM-MSCs) in the treatment of diabetic male mice with CLI model. Supernatants were collected from C57BL/6 mice isolated AT-MSCs and BM-MSCs, afterward their effects on human umbilical vein endothelial (HUVEC) migration potential were evaluated. Diabetes mellitus type 1 was induced by streptozotocin injection. Diabetic mice with CLI model were divided into three groups and injected with AT-MSCs, BM-MSCs, or PBS then the efficacy of them was assessed. Survival of MSCs was analysed by SRY-specific gene. The conditioned medium of AT-MSCs and BM-MSCs stimulated HUVECs migration and the donor cells were detected till 21 day in two groups. BM-MSCs and AT-MSCs improved significantly functional recovery and ischemia damage. Neovascularization in ischemic muscle was significantly higher in mice treated with AT-MSCs and BM-MSCs and they improved muscle regeneration. In vivo and in vitro findings show that AT-MSCs and BM-MSCs transplantation could be proposed as a promising therapy to promote angiogenesis and muscle regeneration through secretion of proangiogenic factors, cytokines and growth factors in diabetic mice with CLI model wherein blood supply is insufficient and disrupted.

New prospects of mesenchymal stem cells for ameliorating temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is present in 30% of epileptic patients and does not respond to conventional treatments. Bone marrow derived mesenchymal stem cells (BMSCs) induce endogenous neural stem cells, inhibit neurodegeneration, and promote brain self-repair mechanisms. The present study addresses the feasibility of BMSCs transplantation against pilocarpine-induced TLE experimentally. BMSCs were injected either intravenously (IV) or in hippocampus bilaterally (IC). Increased cell count of BMSCs was achieved via IC route. BMSCs treatment ameliorated the pilocarpine-induced neurochemical and histological changes, retained amino acid neurotransmitters to the normal level, downregulated the immunoreactivity to insulin growth factor-1 receptor, synaptophysin, and caspase-3 and reduced oxidative insult and inflammatory markers detected in epileptic model. It is worth noting that BMSCs IC-administered showed more pronounced effects than those administered via IV route. BMSCs transplantation presents a promise for TLE treatment that has to be elucidated clinically.

Extracellular vesicles of ETV2 transfected fibroblasts stimulate endothelial cells and improve neovascularization in a murine model of hindlimb ischemia

Ischemia are common conditions related to lack of blood supply to tissues. Depending on the ischemic sites, ischemia can cause different diseases, such as hindlimb ischemia, heart infarction and stroke. This study aims to evaluate how extracellular vesicles (EVs) derived from ETV2 transfected fibroblasts affect endothelial cell proliferation and neovascularization in a murine model of hindlimb ischemia. Human fibroblasts were isolated and cultured under standard conditions and expanded to the 3th passage before use in experiments. Human fibroblasts were transduced with a viral vector containing the ETV2 gene. Transduced cells were selected by puromycin treatment. These cells were further cultured for collection of EVs, which were isolated from culture supernatant. Following co-culture with endothelial cells, EVs were evaluated for their effect on endothelial cell proliferation and were directly injected into ischemic tissues of a murine model of hindlimb ischemia. The results showed that EVs could induce endothelial cell proliferation in vitro and improved neovascularization in a murine model of hindlimb ischemia. Our results suggest that EVs derived from ETV2-transfected fibroblasts can be promising non-cellular products for the regeneration of blood vessels.