Endothelial progenitor cells from human fetal aorta cure diabetic foot in a rat model

Preclinical study of diabetic foot ulcers: From pathogenesis to vivo/vitro models and clinical therapeutic transformation

Diabetic foot ulcer (DFU), a common intractable chronic complication of diabetes mellitus (DM), has a prevalence of up to 25%, with more than 17% of the affected patients at risk of amputation or even death. Vascular risk factors, including vascular stenosis or occlusion, dyslipidemia, impaired neurosensory and motor function, and skin infection caused by trauma, all increase the risk of DFU in patients with diabetes. Therefore, diabetic foot is not a single pathogenesis. Preclinical studies have contributed greatly to the pathogenesis determination and efficacy evaluation of DFU. Many therapeutic tools are currently being investigated using DFU animal models for effective clinical translation. However, preclinical animal models that completely mimic the pathogenesis of DFU remain unexplored. Therefore, in this review, the preparation methods and evaluation criteria of DFU animal models with three major pathological mechanisms: neuropathy, angiopathy and DFU infection were discussed in detail. And the advantages and disadvantages of various DFU animal models for clinical sign simulation. Furthermore, the current status of vitro models of DFU and some preclinical studies have been transformed into clinical treatment programs, such as medical dressings, growth factor therapy, 3D bioprinting and pre-vascularization, Traditional Chinese Medicine treatment. However, because of the complexity of the pathological mechanism of DFU, the clinical transformation of DFU model still faces many challenges. We need to further optimize the existing preclinical studies of DFU to provide an effective animal platform for the future study of pathophysiology and clinical treatment of DFU.

Application of Electrospun Nanofiber Membrane in the Treatment of Diabetic Wounds

Diabetic wounds are complications of diabetes which are caused by skin dystrophy because of local ischemia and hypoxia. Diabetes causes wounds in a pathological state of inflammation, resulting in delayed wound healing. The structure of electrospun nanofibers is similar to that of the extracellular matrix (ECM), which is conducive to the attachment, growth, and migration of fibroblasts, thus favoring the formation of new skin tissue at the wound. The composition and size of electrospun nanofiber membranes can be easily adjusted, and the controlled release of loaded drugs can be realized by regulating the fiber structure. The porous structure of the fiber membrane is beneficial to gas exchange and exudate absorption at the wound, and the fiber surface can be easily modified to give it function. Electrospun fibers can be used as wound dressing and have great application potential in the treatment of diabetic wounds. In this study, the applications of polymer electrospun fibers, nanoparticle-loaded electrospun fibers, drug-loaded electrospun fibers, and cell-loaded electrospun fibers, in the treatment of diabetic wounds were reviewed, and provide new ideas for the effective treatment of diabetic wounds.

Guidelines and standards for comprehensive clinical diagnosis and interventional treatment for diabetic foot in China (Issue 7.0)

Diabetic foot (DF) is one of the most common complications of diabetes and is associated with high morbidity, disability, lethality and low cure-rate. The clinical diagnosis and treatment of DF need to be standardized. The Chinese Diabetic Foot Cell and Interventional Therapy Technology Alliance has released six editions of guidelines and standards for clinical diagnosis and interventional treatment of DF, which filled the gap in the domestic DF treatment standard and played an important role in improving the level of diagnosis and treatment in China. In line with the latest developments in diagnosis and treatment, the Alliance, along with other 89 institutions, developed and issued the new edition based on the sixth edition to help standardize the clinical diagnosis and treatment of DF in China.

Modeling of endothelial cell dysfunction using human induced pluripotent stem cells derived from patients with end-stage renal disease

Background

Endothelial cell (EC) dysfunction is a frequent feature in patients with end-stage renal disease (ESRD). The aim of this study was to generate human induced pluripotent stem cells, differentiate ECs (hiPSC-ECs) from patients with ESRD, and appraise the usefulness of hiPSC-ECs as a model to investigate EC dysfunction.

Methods

We generated hiPSCs using peripheral blood mononuclear cells (PBMCs) isolated from three patients with ESRD and three healthy controls (HCs). Next, we differentiated hiPSC-ECs using the generated hiPSCs and assessed the expression of endothelial markers by immunofluorescence. The differentiation efficacy, EC dysfunction, and molecular signatures of EC-related genes based on microarray analysis were compared between the ESRD and HC groups.

Results

In both groups, hiPSCs and hiPSC-ECs were successfully obtained based on induced pluripotent stem cell or EC marker expression in immunofluorescence and flow cytometry. However, the efficiency of differentiation of ECs from hiPSCs was lower in the ESRD-hiPSCs than in the HC-hiPSCs. In addition, unlike HC-hiPSC-ECs, ESRD-hiPSC-ECs failed to form interconnecting branching point networks in an in vitro tube formation assay. During microarray analysis, transcripts associated with oxidative stress and inflammation were upregulated and transcripts associated with vascular development and basement membrane extracellular matrix components were downregulated in ESRD-hiPSC-ECs relative to in HC-hiPSC-ECs.

Conclusion

ESRD-hiPSC-ECs showed a greater level of EC dysfunction than HC-hiPSC-ECs did based on functional assay results and molecular profiles. hiPSC-ECs may be used as a disease model to investigate the pathophysiology of EC dysfunction in ESRD.

Exosomes from linc00511-overexpressing ADSCs accelerates angiogenesis in diabetic foot ulcers healing by suppressing PAQR3-induced Twist1 degradation

AIMS

We aim to investigate the role of ADSCs (Adipose-derived stem cells)-derived exosomes on regulating angiogenesis in diabetic foot ulcers healing.

METHODS

EPCs (endothelial progenitor cells) from human peripheral blood were applied as in vitro model of angiogenesis. Exosomes isolated from ADSCs culture medium were characterized by electron microscopy, size distribution and biomarker expression. Cell proliferation, migration, apoptosis and angiogenesis were detected by CCK-8 and EdU staining, wound healing, flow cytometry and tube formation assays, respectively. Rat diabetic foot model was further constructed for the evaluation of wound healing and histological alterations.

RESULTS

EPCs from diabetes showed suppressed proliferation, migration and angiogenesis and decreased Twist1 protein. Similarly, high glucose repressed the proliferation, migration and angiogenesis of EPCs, which also elevated PAQR3 and suppressed Twist1 expression. However, these impaired EPCs biological functions were recovered by the application of exosomes from linc00511-overexpressing ADSCs, along with increased Twist1 and decreased PAQR3. Mechanistically, PAQR3 overexpression reduced Twist1 protein level in EPCs by enhancing BTRC-mediated Twist1 ubiquitin degradation. Exosomes from linc00511-overexpressing ADSCs alleviated rat diabetic foot ulcers by inhibiting Twist1 ubiquitination to promote angiogenesis.

CONCLUSION

Exosomes from linc00511-overexpressing ADSCs promotes diabetic foot ulcers healing by accelerating angiogenesis via suppressing PAQR3-induced Twist1 ubiquitin degradation.

Current Status of Angiogenic Cell Therapy and Related Strategies Applied in Critical Limb Ischemia

Critical limb ischemia (CLI) constitutes the most severe form of peripheral arterial disease (PAD), it is characterized by progressive blockade of arterial vessels, commonly correlated to atherosclerosis. Currently, revascularization strategies (bypass grafting, angioplasty) remain the first option for CLI patients, although less than 45% of them are eligible for surgical intervention mainly due to associated comorbidities. Moreover, patients usually require amputation in the short-term. Angiogenic cell therapy has arisen as a promising alternative for these "no-option" patients, with many studies demonstrating the potential of stem cells to enhance revascularization by promoting vessel formation and blood flow recovery in ischemic tissues. Herein, we provide an overview of studies focused on the use of angiogenic cell therapies in CLI in the last years, from approaches testing different cell types in animal/pre-clinical models of CLI, to the clinical trials currently under evaluation. Furthermore, recent alternatives related to stem cell therapies such as the use of secretomes, exosomes, or even microRNA, will be also described.

Combined analysis of circRNA and mRNA profiles and interactions in patients with Diabetic Foot and Diabetes Mellitus

In order to elucidate the pathogenesis and explore new biomarkers for diabetes and diabetic foot (DF), an analysis using RNA sequencing affords broader insights into gene expression regulatory networks in DF. To better explore the molecular basis of DF, we carried out an analysis of circular RNA (circRNA) and messenger RNA (mRNA) expression profiles of serum samples from DF patients and diabetes mellitus (DM) patients. The potential roles and interactions of differentially expressed circRNAs and mRNAs were classified by gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses. Compared with diabetes patients, 279 mRNAs were upregulated and 353 mRNAs were downregulated in the serum of DF patients, and 33 circRNAs were differently expressed. The differential genes at the nodes of the interaction network were screened, and TLR6 RUNX1 and ST2 were found to be related to the progression of diabetes and DF. The enrichment pathway analysis revealed that the lysosomal pathway played a critical role in the occurrence and development of DF. TLR6, RUNX1, and ST2 mRNA expressions and the lysosomal pathway may be involved in the pathogenesis of diabetes and DF. In addition, methane metabolism and Chagas disease pathways were observed in the occurrence and development of DF, which is a new discovery in this study. This study provides clues on the molecular mechanisms of DF at the circRNA and mRNA levels.

Epicardial cell lineages and the origin of the coronary endothelium

The embryonic epicardium generates a population of epicardial-derived mesenchymal cells (EPDC) whose contribution to the coronary endothelium is minor or, according to some reports, negligible. We have compared four murine cell-tracing models related to the EPDC in order to elucidate this contribution. Cre recombinase was expressed under control of the promoters of the Wilms' tumor suppressor (Wt1), the cardiac troponin (cTnT), and the GATA5 genes, activating expression of the R26R^EYFP reporter. We have also used the G2 enhancer of the GATA4 gene as a driver due to its activation in the proepicardium. Recombination was found in most of the epicardium/EPDC in all cases. The contribution of these lineages to the cardiac endothelium was analyzed using confocal microscopy and flow cytometry. G2-GATA4 lineage cells are the most frequent in the endothelium, probably due to the recruitment of circulating endothelial progenitors. The contribution of the WT1 cell lineage increases along gestation due to further endothelial expression of WT1. GATA5 and cTnT lineages represent 4% of the cardiac endothelial cells throughout the gestation, probably standing for the actual EPDC contribution to the coronary endothelium. These results suggest caution when using a sole cell-tracing model to study the fate of the EPDC.

Monocytes as Endothelial Progenitor Cells (EPCs), Another Brick in the Wall to Disentangle Tumor Angiogenesis

Bone marrow contains endothelial progenitor cells (EPCs) that, upon pro-angiogenic stimuli, migrate and differentiate into endothelial cells (ECs) and contribute to re-endothelialization and neo-vascularization. There are currently no reliable markers to characterize EPCs, leading to their inaccurate identification. In the past, we showed that, in a panel of tumors, some cells on the vessel wall co-expressed CD14 (monocytic marker) and CD31 (EC marker), indicating a putative differentiation route of monocytes into ECs. Herein, we disclosed monocytes as potential EPCs, using in vitro and in vivo models, and also addressed the cancer context. Monocytes acquired the capacity to express ECs markers and were able to be incorporated into blood vessels, contributing to cancer progression, by being incorporated in tumor neo-vasculature. Reactive oxygen species (ROS) push monocytes to EC differentiation, and this phenotype is reverted by cysteine (a scavenger and precursor of glutathione), which indicates that angiogenesis is controlled by the interplay between the oxidative stress and the scavenging capacity of the tumor microenvironment.

Wnt3a involved in the mechanical loading on improvement of bone remodeling and angiogenesis in a postmenopausal osteoporosis mouse model

Osteoporosis is a major health problem, making bones fragile and susceptible to fracture. Previous works showed that mechanical loading stimulated bone formation and accelerated fracture healing. Focusing on the role of Wnt3a (wingless/integrated 3a), this study was aimed to assess effects of mechanical loading to the spine, using ovariectomized (OVX) mice as a model of osteoporosis. Two-week daily application of this novel loading (4 N, 10 Hz, 5 min/d) altered bone remodeling with an increase in Wnt3a. Spinal loading promoted osteoblast differentiation, endothelial progenitor cell migration, and tube formation and inhibited osteoclast formation, migration, and adhesion. A transient silencing of Wnt3a altered the observed loading effects. Spinal loading significantly increased bone mineral density, bone mineral content, and bone area per tissue area. The loaded OVX group showed a significant increase in the number of osteoblasts and reduction in osteoclast surface/bone surface. Though expression of osteoblastic genes was increased, the levels of osteoclastic genes were decreased by loading. Spinal loading elevated a microvascular volume as well as VEGF expression. Collectively, this study supports the notion that Wnt3a-mediated signaling involves in the effect of spinal loading on stimulating bone formation, inhibiting bone resorption, and promoting angiogenesis in OVX mice. It also suggests that Wnt3a might be a potential therapeutic target for osteoporosis treatment.-Li, X., Liu, D., Li, J., Yang, S., Xu, J., Yokota, H., Zhang, P. Wnt3a involved in the mechanical loading on improvement of bone remodeling and angiogenesis in a postmenopausal osteoporosis mouse model.

Exosomes of Endothelial Progenitor Cells Inhibit Neointima Formation After Carotid Artery Injury

BACKGROUND

Exosomes released from endothelial progenitor cells (EPCs) play a protective role in various disease models. Both endothelial cell (EC) damage and smooth muscle cell (SMC) proliferation are involved in the pathological process of restenosis after angioplasty and stenting. Few studies have focused on the therapeutic role of exosomes in EC damage and SMC proliferation. In this study, we sought to investigate the effect of exosomes released by human fetal aorta-derived EPCs on the rat carotid artery balloon injury model in vivo. We also sought to determine the effect of exosomes on both ECs and SMCs in vitro.

METHODS

Exosomes (Exo group) or saline (Con group) were injected in rat carotid balloon injury model animals. The rats were sacrificed after 2, 4, 14, and 28 d, and injured carotid specimens were collected for Evans blue staining, hematoxylin-eosin staining, and immunohistochemistry.

RESULTS

When the Con group and the Exo group were compared, the reendothelialized areas were not significantly different after 2 or 4 d, as shown by Evans blue staining. The hematoxylin-eosin results showed that the intimal to medial area ratio was slightly but not significantly higher in the Exo group after 2 and 4 d. The immunohistochemistry results showed that the proliferation of SMCs was slightly higher in the Exo group after 2 and 4 d, but the difference was not significant. The reendothelialization area of the Con group was significantly smaller than that of the Exo group at day 14. Both the intimal to medial area ratio and SMC proliferation in the Exo group were significantly smaller than those of the Con group at 14 or 28 d. In the in vitro study, exosome treatment significantly enhanced the proliferation and migration of both ECs and SMCs.

CONCLUSIONS

Exosomes derived from EPCs could inhibit neointimal hyperplasia after carotid artery injury in rats. The protective effect of exosomes may manifest through the promotion of EC repair rather than direct suppression of proliferation and migration of smooth muscles cells.

A novel dressing seeded with embryonic artery CD133+ cells and loaded with the Sirt1 agonist SRT1720 accelerates the healing of diabetic ischemic ulcers

Refractory ischemic ulcers that occur in patients with diabetes present a major clinical challenge. Embryonic artery cluster of differentiation 133⁺ cells (EACCs) may promote the healing of diabetic ulcers; however, the high glucose environment in the diabetic ulcers decreases the survival rate of transplanted EACCs and inhibit their biological function. Furthermore, microcirculation in diabetic ischemic ulcers is impaired, which inhibits the beneficial effect of EACCs. In the current study, the Sirt1 agonist SRT1720 was selected as a therapeutic drug and loaded into a dressing composed of PLGA, collagen and silk (PCSS) formed using electrospinning technology. EACCs were seeded onto the PCSS dressing and this was used to treat diabetic ulcers. The results indicated that SRT1720 promotes the proliferation of EACCs, enhances the secretion of vascular endothelial growth factor A, interluekin 8 and basic fibroblast growth factor, and inhibits the secretion of tumor necrosis factor α. Furthermore, SRT1720 promoted the paracrine function of EACCs and promoted the proliferation and migration of human umbilical vein endothelial cells. PCSS induced the steady release of SRT1720 over a 15-day period and PCSS seeded with EACCs (PCSS-EACCs) were transplanted into the diabetic ischemic ulcers of mice with diabetes. The results of these experiments indicated that angiogenesis and the healing of diabetic ischemic ulcers was significantly improved following the transplantation of PCSS-EACCs. Therefore, PCSS-EACCs may be a novel and effective treatment for diabetic ischemic ulcers.