Exendin-4 in combination with adipose-derived stem cells promotes angiogenesis and improves diabetic wound healing

Incretin-based therapy and the risk of diabetic foot ulcers and related events

AIM

To investigate the effect of dipeptidyl peptidase-4 inhibitors (DPP4-Is) and glucagon-like peptide-1 receptor agonists (GLP1-RAs) on diabetic foot ulcer (DFU) and DFU-related outcomes (lower limb amputation [LLA], DFU-related hospitalization and mortality).

METHODS

We performed a cohort study with data from the Clinical Practice Research Datalink Aurum database with linkage to hospital data. We included people with type 2 diabetes starting treatment with metformin. Then we propensity score matched new users of DPP4-Is and sulphonylureas (N = 98 770), and new users of GLP1-RAs and insulin (N = 25 422). Cox proportional hazards models estimated the hazard ratios (HRs) for the outcomes.

RESULTS

We observed a lower risk of DFU with both DPP4-I use versus sulphonylurea use (HR 0.88, 95% confidence interval [CI]: 0.79-0.97) and GLP1-RA use versus insulin use (HR 0.44, 95% CI: 0.32-0.60) for short-term exposure (≤ 400 days) and HR 0.74 (95% CI: 0.60-0.92) for long-term exposure (>400 days). Furthermore, the risks of hospitalization and mortality were lower with both DPP4-I use and GLP1-RA use. The risk of LLA was lower with GLP1-RA use. The results remained consistent across several sensitivity analyses.

CONCLUSIONS

Incretin-based therapy was associated with a lower risk of DFU and DFU-related outcomes. This suggests benefits for the use of this treatment in people at risk of DFU.

Diabetic microenvironment deteriorates the regenerative capacities of adipose mesenchymal stromal cells

BACKGROUND

Type 2 diabetes is an endocrine disorder characterized by compromised insulin sensitivity that eventually leads to overt disease. Adipose stem cells (ASCs) showed promising potency in improving type 2 diabetes and its complications through their immunomodulatory and differentiation capabilities. However, the hyperglycaemia of the diabetic microenvironment may exert a detrimental effect on the functionality of ASCs. Herein, we investigate ASC homeostasis and regenerative potential in the diabetic milieu.

METHODS

We conducted data collection and functional enrichment analysis to investigate the differential gene expression profile of MSCs in the diabetic microenvironment. Next, ASCs were cultured in a medium containing diabetic serum (DS) or normal non-diabetic serum (NS) for six days and one-month periods. Proteomic analysis was carried out, and ASCs were then evaluated for apoptosis, changes in the expression of surface markers and DNA repair genes, intracellular oxidative stress, and differentiation capacity. The crosstalk between the ASCs and the diabetic microenvironment was determined by the expression of pro and anti-inflammatory cytokines and cytokine receptors.

RESULTS

The enrichment of MSCs differentially expressed genes in diabetes points to an alteration in oxidative stress regulating pathways in MSCs. Next, proteomic analysis of ASCs in DS revealed differentially expressed proteins that are related to enhanced cellular apoptosis, DNA damage and oxidative stress, altered immunomodulatory and differentiation potential. Our experiments confirmed these data and showed that ASCs cultured in DS suffered apoptosis, intracellular oxidative stress, and defective DNA repair. Under diabetic conditions, ASCs also showed compromised osteogenic, adipogenic, and angiogenic differentiation capacities. Both pro- and anti-inflammatory cytokine expression were significantly altered by culture of ASCs in DS denoting defective immunomodulatory potential. Interestingly, ASCs showed induction of antioxidative stress genes and proteins such as SIRT1, TERF1, Clusterin and PKM2.

CONCLUSION

We propose that this deterioration in the regenerative function of ASCs is partially mediated by the induced oxidative stress and the diabetic inflammatory milieu. The induction of antioxidative stress factors in ASCs may indicate an adaptation mechanism to the increased oxidative stress in the diabetic microenvironment.

Adipose-derived stem cells in diabetic foot care: Bridging clinical trials and practical application

Diabetic foot ulcers (DFUs) pose a critical medical challenge, significantly im-pairing the quality of life of patients. Adipose-derived stem cells (ADSCs) have been identified as a promising therapeutic approach for improving wound healing in DFUs. Despite extensive exploration of the mechanical aspects of ADSC therapy against DFU, its clinical applications remain elusive. In this review, we aimed to bridge this gap by evaluating the use and advancements of ADSCs in the clinical management of DFUs. The review begins with a discussion of the classification and clinical management of diabetic foot conditions. It then discusses the current landscape of clinical trials, focusing on their geographic distribution, reported efficacy, safety profiles, treatment timing, administration techniques, and dosing considerations. Finally, the review discusses the preclinical strategies to enhance ADSC efficacy. This review shows that many trials exhibit biases in study design, unclear inclusion criteria, and intervention protocols. In conclusion, this review underscores the potential of ADSCs in DFU treatment and emphasizes the critical need for further research and refinement of therapeutic approaches, with a focus on improving the quality of future clinical trials to enhance treatment outcomes and advance the field of diabetic wound care.

α-ketoglutarate preconditioning extends the survival of engrafted adipose-derived mesenchymal stem cells to accelerate healing of burn wounds

The application of adipose-derived stem cells (ADSCs) in treating hard-to-heal wounds has been widely accepted, while the short-term survival rate remains an obstacle in stem cell therapy. The aim of this study is to investigate the effect of preconditioning ADSCs with α-ketoglutarate (α-KG) on the healing of acid burn wounds and cell survival within wounds. Preconditioning of ADSCs was performed by treating cells at passage 3 with 3.5 mM DM-αKG for 24 h. Proliferation and migration of ADSCs was examined. An acid burn wound was created on the dorsal skin of mice. Cell suspension of ADSCs (2 × 106 cells/ml), either pre-treated with α-KG or not, was injected subcutaneously around the margin of wound. At 1,4,7,10,14 days after injection, the percentage of wound closure was evaluated. Expression of pro-angiogenic factors, matrix molecules and HIF1-α in pretreated ADSCs or in wounds was evaluated by qRT-PCR and immunohistochemistry staining, respectively. The survival rate of DiO-labelled ADSCs was determined with the in vivo bioluminescent imaging system. Treating with α-KG induced an enhancement in migration of ADSCs, while their proliferation was not affected. Expression of Vegf and Fgf-2 was significantly increased. With injection of pretreated ADSCs, healing of wounds was remarkably accelerated, along with increased ECM deposition and microvessel density. Moreover, pretreatment with α-KG resulted a prolonged survival of engrafted ADSCs was observed. Expression of HIF-1α was significantly increased in ADSCs treated with α-KG and in wounds injected with preconditioned ADSCs. Our results revealed that healing of acid burn wound was accelerated with administration of ADSCs pretreated with α-KG, which induced elevated expression of HIF-1α and prolonged survival of engrafted stem cells.

The efficacy of adipose-derived stem cells in burn injuries: a systematic review

BACKGROUND

Burn injuries can be associated with prolonged healing, infection, a substantial inflammatory response, extensive scarring, and eventually death. In recent decades, both the mortality rates and long-term survival of severe burn victims have improved significantly, and burn care research has increasingly focused on a better quality of life post-trauma. However, delayed healing, infection, pain and extensive scar formation remain a major challenge in the treatment of burns. ADSCs, a distinct type of mesenchymal stem cells, have been shown to improve the healing process. The aim of this review is to evaluate the efficacy of ADSCs in the treatment of burn injuries.

METHODS

A systematic review of the literature was conducted using the electronic databases PubMed, Web of Science and Embase. The basic research question was formulated with the PICO framework, whereby the usage of ADSCs in the treatment of burns in vivo was determined as the fundamental inclusion criterion. Additionally, pertinent journals focusing on burns and their treatment were screened manually for eligible studies. The review was registered in PROSPERO and reported according to the PRISMA statement.

RESULTS

Of the 599 publications screened, 21 were considered relevant to the key question and were included in the present review. The included studies were almost all conducted on rodents, with one exception, where pigs were investigated. 13 of the studies examined the treatment of full-thickness and eight of deep partial-thickness burn injuries. 57,1 percent of the relevant studies have demonstrated that ADSCs exhibit immunomodulatory effects during the inflammatory response. 16 studies have shown improved neovascularisation with the use of ADSCs. 14 studies report positive influences of ADSCs on granulation tissue formation, while 11 studies highlight their efficacy in promoting re-epithelialisation. 11 trials demonstrated an improvement in outcomes during the remodelling phase.

CONCLUSION

In conclusion, it appears that adipose-derived stem cells demonstrate remarkable efficacy in the field of regenerative medicine. However, the usage of ADSCs in the treatment of burns is still at an early experimental stage, and further investigations are required in order to examine the potential usage of ADSCs in future clinical burn care.

Progress and application of adipose-derived stem cells in the treatment of diabetes and its complications

Diabetes mellitus (DM) is a serious chronic metabolic disease that can lead to many serious complications, such as cardiovascular disease, retinopathy, neuropathy, and kidney disease. Once diagnosed with diabetes, patients need to take oral hypoglycemic drugs or use insulin to control blood sugar and slow down the progression of the disease. This has a significant impact on the daily life of patients, requiring constant monitoring of the side effects of medication. It also imposes a heavy financial burden on individuals, their families, and even society as a whole. Adipose-derived stem cells (ADSCs) have recently become an emerging therapeutic modality for DM and its complications. ADSCs can improve insulin sensitivity and enhance insulin secretion through various pathways, thereby alleviating diabetes and its complications. Additionally, ADSCs can promote tissue regeneration, inhibit inflammatory reactions, and reduce tissue damage and cell apoptosis. The potential mechanisms of ADSC therapy for DM and its complications are numerous, and its extensive regenerative and differentiation ability, as well as its role in regulating the immune system and metabolic function, make it a powerful tool in the treatment of DM. Although this technology is still in the early stages, many studies have already proven its safety and effectiveness, providing new treatment options for patients with DM or its complications. Although based on current research, ADSCs have achieved some results in animal experiments and clinical trials for the treatment of DM, further clinical trials are still needed before they can be applied in a clinical setting.

Treatment of type 2 diabetes mellitus with stem cells and antidiabetic drugs: a dualistic and future-focused approach

Type 2 Diabetes Mellitus (T2DM) accounts for more than 90% of total diabetes mellitus cases all over the world. Obesity and lack of balance between energy intake and energy expenditure are closely linked to T2DM. Initial pharmaceutical treatment and lifestyle interventions can at times lead to remission but usually help alleviate it to a certain extent and the condition remains, thus, recurrent with the patient being permanently pharmaco-dependent. Mesenchymal stromal cells (MSCs) are multipotent, self-renewing cells with the ability to secrete a variety of biological factors that can help restore and repair injured tissues. MSC-derived exosomes possess these properties of the original stem cells and are potentially able to confer superior effects due to advanced cell-to-cell signaling and the presence of stem cell-specific miRNAs. On the other hand, the repository of antidiabetic agents is constantly updated with novel T2DM disease-modifying drugs, with higher efficacy and increasingly convenient delivery protocols. Delving deeply, this review details the latest progress and ongoing studies related to the amalgamation of stem cells and antidiabetic drugs, establishing how this harmonized approach can exert superior effects in the management and potential reversal of T2DM.

Transplantation of adipose derived stem cells in diabetes mellitus; limitations and achievements

Objectives

Diabetes mellitus (DM) is a complex metabolic disease that results from impaired insulin secreting pancreatic β-cells or insulin resistance. Although available medications help control the disease, patients suffer from its complications. Therefore, finding effective therapeutic approaches to treat DM is a priority. Adipose Derived Stem Cells (ADSCs) based therapy is a promising strategy in various regenerative medicine applications, but its systematic translational use is still somewhat out of reach. This review is aimed at clarifying achievements as well as challenges facing the application of ADSCs for the treatment of DM, with a special focus on the mechanisms involved.

Methods

Literature searches were carried out on "Scopus", "PubMed" and "Google Scholar" up to September 2022 to find relevant articles in the English language for the scope of this review.

Results

Recent evidence showed a significant role of ADSC therapies in DM by ameliorating insulin resistance and hyperglycemia, regulating hepatic glucose metabolism, promoting β cell function and regeneration, and functioning as a gene delivery tool. In addition, ADSCs could improve diabetic wound healing by promoting collagen deposition, inhibiting inflammation, and enhancing angiogenesis.

Conclusion

Overall, this literature review revealed the great clinical implications of ADSCs for translating into the clinical setting for the treatment of diabetes. However, further large-scale and controlled studies are needed to overcome challenges and confirm the safety and optimal therapeutic scheme before daily clinical application.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01280-8.

The Utilization of Glucagon-like Peptide 1 Agonists and Risk of Following External Eye Diseases in Type 2 Diabetes Mellitus Individuals: A Population-Based Study

The glucagon-like peptide 1 (GLP-1) agonist showed anti-hyperglycemic and anti-inflammatory effects, which may retard the risk of external eye disease. The protective effect of GLP-1 agonist and dry eye disease (DED) was found, while the relationship between GLP-1 agonist and other corneal diseases was not clear. Herein, we aim to evaluate the association between the usage of GLP-1 agonists and the development of the following external eye disease in type 2 diabetes mellitus (T2DM) patients. A retrospective cohort study using the National Health Insurance Research Database (NHIRD) of Taiwan was conducted. The T2DM patients were divided into those with GLP-1 treatment and those without GLP-1 treatment and matched with a 1:2 ratio. The main outcomes were the development of dry eye disease (DED), superficial keratitis, and infectious keratitis. The Cox proportional hazard regression was adopted to produce the adjusted hazard ratio (aHR) with a 95% confidence interval (CI) of external eye diseases between groups. There were 115, 54, and 11 episodes of DED, superficial keratitis, and infectious keratitis in the GLP-1 group. Another 280, 168, and 31 events of DED, superficial keratitis, and infectious keratitis were recorded in the control group. The GLP-1 group demonstrated a significantly lower incidence of DED (aHR: 0.853, 95% CI: 0.668-0.989, p = 0.0356) and superficial keratitis (aHR: 0.670, 95% CI: 0.475-0.945, p = 0.0107) compared to the control group. In the subgroup analyses, the correlation of GLP-1 agonist and DED development was more prominent in patients younger than 60 years old (p = 0.0018). In conclusion, the GLP-1 agonist treatments are significantly associated with a lower incidence of subsequent DED and superficial keratitis, while the relationship was not significant between GLP-1 agonist usage and infectious keratitis.

Long-term follow-up and exploration of the mechanism of stromal vascular fraction gel in chronic wounds

BACKGROUND

Chronic refractory wounds easily relapse and seriously affect the patients' quality of life. Previous studies have shown that stromal vascular fraction gel (SVF-gel) significantly promotes the early healing of chronic wounds; however, the mechanisms of SVF-gel function per se remain unclear, and a long-term follow-up is lacking. This study aims to explore the mechanisms of SVF-gel promoting the healing of chronic wounds and follow up the long-term efficacy of SVF-gel.

METHODS

Autologous SVF-gel transplantation was performed in 20 patients with chronic wounds (from March 2016 to September 2019), and the size of the wound before and after SVF-gel transplantation was observed. The conditioned medium (CM) was harvested from SVF-gel under serum-free, serum-deprivation and 10% fetal bovine serum (FBS) microenvironment in vitro, respectively. The concentration of the growth factors in the two kinds of gel-CM was tested, and their effects on the proliferation and migration of human dermal fibroblasts (HDFs) were detected.

RESULTS

All patients had 100% wound closure eventually, and the average time to complete closure was 28.3 ± 9.7 days. The time of follow-up ranged from 2 to 6 years, and there was no wound recurrence. Interestingly, the concentrations of epidermal growth factor and transforming growth factor β1 of the CM were higher in serum-free and serum-deprivation condition than in 10% FBS microenvironment (p < 0.05). Correspondingly, the proliferation and migration ability of HDFs treated with gel-CM from serum-free condition were stronger than those treated with gel-CM from serum-deprivation (2% FBS) or 10% FBS microenvironment (p < 0.05).

CONCLUSION

These results indicate that it is safe, effective, and lasting in effect to treat chronic wounds with SVF-gel and mechanisms of action that include secreting various cytokines and promoting cell proliferation and migration ability.

TRIAL REGISTRATION

Chinese Clinical Trail Registry, ChiCTR2000034624. Registered 12 July 2020-Retrospectively registered, http://www.chictr.org.cn/showproj.aspx?proj=56058.

Lupeol-loaded chitosan-Ag+ nanoparticle/sericin hydrogel accelerates wound healing and effectively inhibits bacterial infection

Lupeol, a pentacyclic triterpene, has demonstrated significant wound healing properties; however, its low water solubility has limited its clinical applicability. To overcome this limitation, we utilized Ag⁺-modified chitosan (CS-Ag) nanoparticles to deliver lupeol, resulting in the formation of CS-Ag-L-NPs. These nanoparticles were then encapsulated within a temperature-sensitive, self-assembled sericin hydrogel. Various analytical methods, including SEM, FTIR, XRD, HPLC, TGA assay, hemolysis and antibacterial activity tests, were employed to characterize the nanoparticles. Additionally, an infectious wound model was used to evaluate the therapeutic and antibacterial efficacy of the CS-Ag-L-NPs modified sericin hydrogel. Our results showed that the encapsulation efficiency of lupeol in CS-Ag-L-NPs reached 62.1 %, with good antibacterial activity against both gram-positive and gram-negative bacteria and a low hemolysis ratio (<5 %). The CS-Ag-L-NPs sericin gel exhibited multiple beneficial effects, including inhibiting bacterial proliferation in wound beds, promoting wound healing via accelerated re-epithelialization, reducing inflammation, and enhancing collagen fiber deposition. We conclude that the CS-Ag-L-NPs loaded sericin hydrogel has tremendous potential for development as a multifunctional therapeutic platform capable of accelerating wound healing and effectively suppressing bacterial infections in clinical settings.

Calcium silicate-stimulated adipose-derived stem cells promote angiogenesis and improve skin wound healing

Skin wound healing is a complicated process involving proliferation, inflammation, coagulation, and hemostasis, and scar tissue formation of wound repairing. Adipose-derived stem cells (ADSCs) have presented potential therapeutic effects in the non-healing and chronic wound. Calcium silicate (CS) ceramics have been identified as a new type of bioceramics for tissue construction and regeneration. Here, we aimed to explore the impact of CS on the regulation of ADSCs-mediated wound healing. Significantly, CS was able to dose-dependently enhance the proliferation of ADSCs. CS inhibited terminal deoxynucleotidyl transferase dUTP nick end labeling positive cells in the H₂O₂-treated ADSCs. Similarly, the Bcl-2 expression was elevated while Bax and cleaved caspase-3 expression were repressed by CS in the cells. CS could induce migration and reduce oxidative stress of ADSCs. Moreover, immunofluorescence analysis and Western blot analysis showed that CS could promote CXCR4 expression in ADSCs. Moreover, CS-stimulated ADSCs enhanced migration and angiogenic capacity of HUVEC. Importantly, CS-stimulated ADSCs improved wound healing in full-thickness skin defect mouse model. Thus, we conclude that CS improves ADSCs-attenuated wound healing in vivo and in vitro. Our finding presents novel insight in the scenario that CS regulates ADSCs and wound healing. CS may be applied as potential materials for the treatment of wound healing.

Human Fibroblast Growth Factor-Treated Adipose-Derived Stem Cells Facilitate Wound Healing and Revascularization in Rats with Streptozotocin-Induced Diabetes Mellitus

Diabetes mellitus contributes to 15-25% of all chronic foot ulcers. Peripheral vascular disease is a cause of ischemic ulcers and exacerbates diabetic foot disease. Cell-based therapies are viable options to restore damaged vessels and induce the formation of new vessels. Adipose-derived stem cells (ADSCs) have the potential for angiogenesis and regeneration because of their greater paracrine effect. Preclinical studies are currently using other forced enhancement techniques (e.g., genetic modification or biomaterials) to increase the efficacy of human ADSC (hADSC) autotransplantation. Unlike genetic modifications and biomaterials, many growth factors have been approved by the equivalent regulatory authorities. This study confirmed the effect of enhanced human ADSC (ehADSC)s with a cocktail of FGF and other pharmacological agents to promote wound healing in diabetic foot disease. In vitro, ehADSCs exhibited a long and slender spindle-shaped morphology and showed significantly increased proliferation. In addition, it was shown that ehADSCs have more functionalities in oxidative stress toleration, stem cell stemness, and mobility. In vivo, the local transplantation of 1.2 × 10⁶ hADSCs or ehADSCs was performed in animals with diabetes induced by STZ. The ehADSC group showed a statistically decreased wound size and increased blood flow compared with the hADSC group and the sham group. Human Nucleus Antigen (HNA) positive cells were observed in some ADSC-transplanted animals. The ehADSC group showed a relatively higher portion of HNA-positive animals than the hADSC group. The blood glucose levels showed no significant difference among the groups. In conclusion, the ehADSCs showed a better performance in vitro, compared with conventional hADSCs. Additionally, a topical injection of ehADSCs into diabetic wounds enhanced wound healing and blood flow, while improving histological markers suggesting revascularization.

Research on the wound healing effect of Shengji Huayu Formula ethanol extract-derived fractions in streptozotocin-induced diabetic ulcer rats

BACKGROUND

Diabetic ulcer is a common complication of diabetes. It is characterized by a long-term disease course and high recurrence rate. Shengji Huayu Formula (SHF) is an effective formula for treating diabetic ulcers. However, the specific effective parts of SHF remain unclear. Clarifying the active polar site of SHF would be helpful to refine research on the components in SHF that promote wound healing. This research aims to focus on evaluating the activity of polar fractions.

METHODS

A diabetic rat model was established by intraperitoneally injecting streptozotocin (STZ) and was adopted to confirm the therapeutic effect of SHF. Four different polarity parts were extracted from SHF and prepared into a cream to evaluate the activity. High-performance liquid chromatography (HPLC) was used to detect chemical constituents in chloroform extracts.

RESULTS

It was discovered that dracorhodin, aloe-emodin, rhein, imperatorin, emodin, isoimperatorin, chrysophanol, physcion, and tanshinone IIA were the main components of the chloroform extract from SHF. The results revealed that chloroform extract could effectively accelerate diabetic wound healing by promoting collagen regeneration and epidermal repair. Chloroform extract of SHF could stimulate the generation of vascular endothelial growth factor (VEGF). The results are also indicated that the effective active fraction was the chloroform part, and the method of detecting the main chemical constituents in the active part was successfully established.

CONCLUSION

SHF could improve diabetic ulcers by promoting granulation tissue synthesis. In this study, four polar parts (petroleum ether, chloroform, ethylacetate, n-butanol) were extracted from a 95% ethanol extract. In contrast, chloroform polar parts showed a higher wound closure rate, stimulated more collagen regeneration and promoted more production of vascular endothelial cells. In conclusion, the chloroform extract of SHF was the effective polar part in ameliorating diabetic wound healing.

Targeting matrix metalloproteases in diabetic wound healing

Chronic inflammation participates in the progression of multiple chronic diseases, including obesity, diabetes mellitus (DM), and DM related complications. Diabetic ulcer, characterized by chronic wounds that are recalcitrant to healing, is a serious complication of DM tremendously affecting the quality of life of patients and imposing a costly medical burden on society. Matrix metalloproteases (MMPs) are a family of zinc endopeptidases with the capacity of degrading all the components of the extracellular matrix, which play a pivotal part in healing process under various conditions including DM. During diabetic wound healing, the dynamic changes of MMPs in the serum, skin tissues, and wound fluid of patients are in connection with the degree of wound recovery, suggesting that MMPs can function as essential biomarkers for the diagnosis of diabetic ulcer. MMPs participate in various biological processes relevant to diabetic ulcer, such as ECM secretion, granulation tissue configuration, angiogenesis, collagen growth, re-epithelization, inflammatory response, as well as oxidative stress, thus, seeking and developing agents targeting MMPs has emerged as a potential way to treat diabetic ulcer. Natural products especially flavonoids, polysaccharides, alkaloids, polypeptides, and estrogens extracted from herbs, vegetables, as well as animals that have been extensively illustrated to treat diabetic ulcer through targeting MMPs-mediated signaling pathways, are discussed in this review and may contribute to the development of functional foods or drug candidates for diabetic ulcer therapy. This review highlights the regulation of MMPs in diabetic wound healing, and the potential therapeutic ability of natural products for diabetic wound healing by targeting MMPs.

Promoting angiogenesis and diabetic wound healing through delivery of protein transduction domain-BMP2 formulated nanoparticles with hydrogel

Decreased angiogenesis contributes to delayed wound healing in diabetic patients. Recombinant human bone morphogenetic protein-2 (rhBMP2) has also been demonstrated to promote angiogenesis. However, the short half-lives of soluble growth factors, including rhBMP2, limit their use in wound-healing applications. To address this limitation, we propose a novel delivery model using a protein transduction domain (PTD) formulated in a lipid nanoparticle (LNP). We aimed to determine whether a gelatin hydrogel dressing loaded with LNP-formulated PTD-BMP2 (LNP-PTD-BMP2) could enhance the angiogenic function of BMP2 and improve diabetic wound healing. In vitro, compared to the control and rhBMP2, LNP-PTD-BMP2 induced greater tube formation in human umbilical vein endothelial cells and increased the cell recruitment capacity of HaCaT cells. We inflicted large, full-thickness back skin wounds on streptozotocin-induced diabetic mice and applied gelatin hydrogel (GH) cross-linked by microbial transglutaminase containing rhBMP2, LNP-PTD-BMP2, or a control to these wounds. Wounds treated with LNP-PTD-BMP2-loaded GH exhibited enhanced wound closure, increased re-epithelialization rates, and higher collagen deposition than those with other treatments. Moreover, LNP-PTD-BMP2-loaded GH treatment resulted in more CD31- and α-SMA-positive cells, indicating greater neovascularization capacity than rhBMP2-loaded GH or GH treatments alone. Furthermore, in vivo near-infrared fluorescence revealed that LNP-PTD-BMP2 has a longer half-life than rhBMP2 and that BMP2 localizes around wounds. In conclusion, LNP-PTD-BMP2-loaded GH is a viable treatment option for diabetic wounds.

hUCMSCs carrying exenatide prevent T1DM by improving intestinal microflora composition and islet tissue damage repair

BACKGROUND

Exenatide is a stable analogue of glucagon-like peptide 1 that can reduce postprandial hyperglycemia and has been utilized as adjunctive therapy for type 1 diabetes mellitus (T1DM). The human umbilical cord is a rich source of MSCs, and human umbilical cord mesenchymal stem cells (hUCMSCs) also show potential to enhance insulin secretion. Here, we aimed to explore the effects of hUCMSCs carrying exenatide in T1DM and further identify the possible mechanisms involved.

METHODS

hUCMSCs were isolated from human umbilical cord tissues, identified, and transduced with recombinant lentivirus carrying exenatide to obtain exenatide-carrying hUCMSCs (hUCMSCs@Ex-4).

RESULTS

The results showed that hUCMSCs@Ex-4 restored the blood glucose levels and body weight of NOD mice, and repressed immune cell infiltration and islet tissue changes. Additionally, in T1DM mice, treatment with hUCMSCs@Ex-4 reduced the blood glucose levels and promoted repair of islet tissue damage. Moreover, hUCMSCs@Ex-4 attenuated renal tissue lesions in T1DM mice. Applying bioinformatic analysis, the effects of hUCMSCs@Ex-4 were suggested to correlate with decreased abundance of pro-inflammatory intestinal bacteria and increased abundance of anti-inflammatory intestinal bacteria.

CONCLUSION

Overall, the study indicated that hUCMSCs carrying exenatide might improve beneficial intestinal microflora abundance and promote islet tissue damage repair, thereby alleviating T1DM.

A Comparative Analysis of the Wound Healing-Related Heterogeneity of Adipose-Derived Stem Cells Donors

Adipose-derived Stem cells (ASCs) are on the verge of being available for large clinical trials in wound healing. However, for developing advanced therapy medicinal products (ATMPs), potency assays mimicking the mode of action are required to control the product consistency of the cells. Thus, greater effort should go into the design of product assays. Therefore, we analyzed three ASC-based ATMPs from three different donors with respect to their surface markers, tri-lineage differentiation, proliferation, colony-forming unit capacity, and effect on fibroblast proliferation and migration, endothelial proliferation, migration, and angiogenesis. Furthermore, the transcriptome of all three cell products was analyzed through RNA-sequencing. Even though all products met the criteria by the International Society for Cell and Gene Therapy and the International Federation for Adipose Therapeutics and Science, we found one product to be consistently superior to others when exploring their potency in the wound healing specific assays. Our results indicate that certain regulatory genes associated with extracellular matrix and angiogenesis could be used as markers of a superior ASC donor from which to use ASCs to treat chronic wounds. Having a panel of assays capable of predicting the potency of the product would ensure the patient receives the most potent product for a specific indication, which is paramount for successful patient treatment and acceptance from the healthcare system.

Advances and perspective on animal models and hydrogel biomaterials for diabetic wound healing

Diabetic wounds are a common complication in diabetes patients. Due to peripheral nerve damage and vascular dysfunction, diabetic wounds are prone to progress to local ulcers, wound gangrene and even to require amputation, bringing huge psychological and economic burdens to patients. However, the current treatment methods for diabetic wounds mainly include wound accessories, negative pressure drainage, skin grafting and surgery; there is still no ideal treatment to promote diabetic wound healing at present. Appropriate animal models can simulate the physiological mechanism of diabetic wounds, providing a basis for translational research in treating diabetic wound healing. Although there are no animal models that can fully mimic the pathophysiological mechanisms of diabetic wounds in humans, it is vital to explore animal simulation models used in basic research and preclinical studies of diabetic wounds. In addition, hydrogel materials are regarded as a promising treatment for diabetic wounds because of their good antimicrobial activity, biocompatibility, biodegradation and appropriate mechanical properties. Herein, we review and discuss the different animal models used to investigate the pathological mechanisms of diabetic wounds. We further discuss the promising future application of hydrogel biomaterials in diabetic wound healing.

Stem Cells and Angiogenesis: Implications and Limitations in Enhancing Chronic Diabetic Foot Ulcer Healing

Nonhealing diabetic foot ulcers (DFUs) are a continuing clinical issue despite the improved treatment with wound debridement, off-loading the ulcer, medication, wound dressings, and preventing infection by keeping the ulcer clean. Wound healing is associated with granulation tissue formation and angiogenesis favoring the wound to enter the resolution phase of healing followed by healing. However, chronic inflammation and reduced angiogenesis in a hyperglycemic environment impair the normal healing cascade and result in chronically non-healing diabetic foot ulcers. Promoting angiogenesis is associated with enhanced wound healing and using vascular endothelial growth factors has been proven beneficial to promote neo-angiogenesis. However, still, nonhealing DFUs persist with increased risks of amputation. Regenerative medicine is an evolving branch applicable in wound healing with the use of stem cells to promote angiogenesis. Various studies have reported promising results, but the associated limitations need in-depth research. This article focuses on summarizing and critically reviewing the published literature since 2021 on the use of stem cells to promote angiogenesis and enhance wound healing in chronic non-healing DFUs.

Potency assays for human adipose-derived stem cells as a medicinal product toward wound healing

In pre-clinical studies, human adipose-derived stem cells (hASCs) have shown great promise as a treatment modality for healing of cutaneous wounds. The advantages of hASCs are that they are relatively easy to obtain in large numbers from basic liposuctions, they maintain their characteristics after long-term in vitro culture, and they possess low immunogenicity, which enables the use of hASCs from random donors. It has been hypothesized that hASCs exert their wound healing properties by reducing inflammation, inducing angiogenesis, and promoting fibroblast and keratinocyte growth. Due to the inherent variability associated with the donor-dependent nature of ASC-based products, it appears necessary that the quality of the different products is prospectively certified using a set of most relevant potency assays. In this review, we present an overview of the available methodologies to assess the Mode and the Mechanism of Action of hASCs, specifically in the wound healing scenario. In conclusion, we propose a panel of potential potency assays to include in the future production of ASC-based medicinal products.

Human adipose-derived stem cell-loaded small intestinal submucosa as a bioactive wound dressing for the treatment of diabetic wounds in rats

Chronic nonhealing wounds are one of the most common and serious complications of diabetes, which can lead to disability of patients. Adipose-derived stem cells (ADSCs) have emerged as a promising tool for skin wound healing, but the therapeutic potential depends considerably on the cell delivery system. Small intestinal submucosa (SIS) is an extracellular matrix-based membranous scaffold with outstanding repair potential for skin wounds. In this study, we first fabricated a bioactive wound dressing, termed the SIS+ADSCs composite, by using human ADSCs as the seed cell and porcine SIS as the cell delivery vehicle. Then, we systematically investigated, for the first time, the healing potential of this wound dressing in a rat model of type 2 diabetes. In vitro studies revealed that SIS provided a favorable microenvironment for ADSCs and significantly promoted the expression of growth factors critical for chronic wound healing. After implantation in the full-thickness skin wounds of diabetic rats, the SIS+ADSCs composite showed a higher wound healing rate and wound healing quality than those in the PBS, ADSCs, and SIS groups. Along with the ability to modulate the polarization of macrophages in vivo, the SIS+ADSCs composite was potent at promoting wound angiogenesis, reepithelialization, and skin appendage regeneration. Taken together, these results indicate that the SIS+ADSCs composite has good therapeutic potential and high translational value for diabetic wound treatment.

Effect of SGLT2 inhibitors versus DPP4 inhibitors or GLP-1 agonists on diabetic foot-related extremity amputation in patients with T2DM: A meta-analysis

AIM

To compare the contribution of sodium-glucose cotransporter-2 inhibitors (SGLT2is) with that of DPP4i or GLP-1ra toward lower extremity amputation rate.

METHODS

Electronic databases were searched for articles published on the differences between the rates of lower extremity amputation among patients with type 2 diabetes mellitus (T2DM) undergoing SGLT2i treatment and those undergoing other anti-hyperglycemic agent (dipeptidyl peptidase-4 inhibitors [DPP4is], glucagon-like peptide-1 receptor agonist [GLP-1as], or sulfonylurea [SUs]) treatments. Random-effect models were used to generate data if heterogeneity was detected.

RESULTS

Eight studies based on retrospective case-control designs with propensity matching were included. The propensity score-matching method increased credibility. Compared with SGLT2i treatment, DPP4i or GLP-1a treatment tended to result in a higher amputation rate (pooled hazard ratio [HR] = 1.1, 95% confidence interval [CI]: 0.98-1.23), whereas SU treatment resulted in similar amputation rates (pooled HR = 0.92, 95% CI: 0.74-1.13). After excluding the heterogeneous study, the meta-analysis of the remaining studies attained a statistical value (pooled HR = 0.81, 95% CI: 0.65-1.01).

CONCLUSION

The study findings suggest that, with respect to diabetic foot-related limb amputations, SGLT2is are not superior to novel anti-hyperglycemic agents (DPP4is and GLP-1as) or other types of oral hypoglycemic agents (SUs). Therefore, SGLT2is may not have significantly positive effects on the prognosis for T2DM patients with complicated diabetic foot.

BCG vaccination and the risk of COVID 19: A possible correlation

Bacillus Calmette-Guérin (BCG) vaccine is currently used to prevent tuberculosis infection. The vaccine was found to enhance resistance to certain types of infection including positive sense RNA viruses. The current COVID-19 pandemic is caused by positive sense RNA, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A higher mortality rate of COVID-19 patients was reported in countries where BCG vaccination is not routinely administered, when compared to the vaccinated ones. We hypothesized that BCG vaccine may control SARS-CoV2 infection via modulating the monocyte immune response. We analyzed GSE104149 dataset to investigate whether human monocytes of BCG-vaccinated individuals acquire resistance to SARS-CoV-2 infection. Differentially expressed genes obtained from the dataset were used to determine enriched pathways, biological processes, and molecular functions for monocytes post BCG vaccination. Our data show that BCG vaccine promotes a more effective immune response of monocytes against SARS-CoV2, but probably not sufficient to prevent the infection.

Adipose-Derived Stem Cells for the Treatment of Diabetic Wound: From Basic Study to Clinical Application

Diabetic wounds significantly affect the life quality of patients and may cause amputation and mortality if poorly managed. Recently, a wide range of cell-based methods has emerged as novel therapeutic methods in treating diabetic wounds. Adipose-derived stem cells (ASCs) are considered to have the potential for widespread clinical application of diabetic wounds treatment in the future. This review summarized the mechanisms of ASCs to promote diabetic wound healing, including the promotion of immunomodulation, neovascularization, and fibro synthesis. We also review the current progress and limitations of clinical studies using ASCs to intervene in diabetic wound healing. New methods of ASC delivery have been raised in recent years to provide a standardized and convenient use of ASCs.

A Review: Matrix Metallopeptidase-9 Nanoparticles Targeted for the Treatment of Diabetic Foot Ulcers

Diabetes foot ulcers are a leading cause of death in diabetic individuals. There are very few medicines and treatments that have received regulatory clearance for this indication, and numerous compounds from various pharmacological classes are now in various stages of clinical studies for diabetic foot ulcers treatment. Multiple risk factors contribute to diabetic foot ulcers, including neuropathy, peripheral artery disease, infection, gender, cigarette smoking, and age. The present difficulties in diabetic foot ulcers treatment are related to bacterial resistance to currently utilized antibiotics. Inhibition of the quorum sensing (QS) system and targeting matrix metallopeptidase-9 (MMP-9) are promising. This study focuses on the difficulties of existing treatment, current treatment technique, and novel pharmacological targets for diabetic foot ulcer. The electronic data base search diabetic for literature on foot ulcers treatment was carried out using Science Direct, PubMed, Google-Scholar, Springer Link, Scopus, and Wiley up to 2021. Becaplermin, a medication that targets MMP-9, glyceryl trinitrate, which inhibits the bacterial quorum sensing system, probiotic therapy, and nano technological solutions are just a few of the novel pharmaceuticals being developed for diabetic foot ulcers treatment. A combination of therapies, rather than one particular agent, will be the best option for treatment of Diabetes foot ulcer since it is multifactorial factors that render occurs of diabetic foot ulcer.

VAP-PLGA microspheres (VAP-PLGA) promote adipose-derived stem cells (ADSCs)-induced wound healing in chronic skin ulcers in mice via PI3K/Akt/HIF-1α pathway

Chronic skin ulcers are a primary global health problem. Velvet antler polypeptide (VAP) regulates endothelial cell migration and angiogenic sprout. Adipose-derived stem cells (ADSCs) are reported to make pivotal impacts upon wound healing. This study aimed to explore the role of VAP combined with ADSCs in wound healing of chronic skin ulcers. The effect of VAP on phenotypes of ADSCs, and VAP (PLGA microspheres) combining with ADSCs on wound healing of chronic skin ulcers in vivo was evaluated. VAP generally promoted the proliferation, migration and invasion of ADSCs, and ADSC-induced angiogenesis in human umbilical vein endothelial cells (HUVECs) through PI3K/Akt/HIF-1α pathway. VAP-PLGA (PLGA microspheres) enhanced the promoting effect of ADSCs on wound healing, pathological changes, and angiogenesis in chronic skin ulcers in vivo. VAP-PLGA intensified the effect of ADSCs on up-regulating the levels of p-PI3K/PI3K, p-Akt/Akt, HIF-1α, vascular endothelial growth factor (VEGF), stromal cell-derived factor-1 (SDF-1), C-X-C motif chemokine receptor 4 (CXCR4), angiopoietin-4 (Ang-4), VEGF receptor (VEGFR), and transforming growth factor-β1 (TGF-β1), and down-regulating the levels of interleukin-1 β (IL-1β), IL-18 and IL-6 in wound tissues in chronic skin ulcers in vivo. Collectively, VAP promoted the growth, migration, invasion, and angiogenesis of ADSCs through activating PI3K/Akt/HIF-1α pathway, and VAP-PLGA enhanced the function of ADSCs in promoting wound healing in vivo, which was associated with angiogenesis, inflammation inhibition, and dermal collagen synthesis.

ADSCs enhance VEGFR3-mediated lymphangiogenesis via METTL3-mediated VEGF-C m6A modification to improve wound healing of diabetic foot ulcers

BACKGROUND

Adipose-derived mesenchymal stem cells (ADSCs) are an important focus in regenerative medicine. However, the biological function of ADSCs in the wound repair of diabetic foot ulcers (DFUs) remains unclear. This study aimed to determine the underlying mechanisms of ADSCs involved in the wound healing of DFUs.

METHODS

The cell surface markers cluster of differentiation 34 (CD34), stromal cell antigen 1 (Stro-1), cluster of differentiation 90 (CD90) and cluster of differentiation 105 (CD105) on ADSCs were identified by flow cytometry. Oil Red O staining and Alizarin Red S staining were performed to identify the multipotential differentiation of ADSCs into adipocytes and bone. The levels of Methyltransferase-like 3 (METTL3), vascular endothelial growth factor C (VEGF-C) and insulin-like growth factor 2 binding protein 2 (IGF2BP2) were assessed by RT-qPCR. CCK-8, Transwell and tubule formation assays were conducted to assess lymphatic endothelial cell (LEC) viability, migration and tubule formation ability, respectively. RIP and RNA pulldown assays were conducted to assess the interaction between IGF2BP2 and VEGF-C. The levels of VEGF-C, VEGFR3, LYVE-1 and IGF2BP2 proteins were assessed by Western blotting. The levels of VEGF-C in LECs were measured by ELISA.

RESULTS

Our findings illustrated that ADSCs accelerate LEC proliferation, migration and lymphangiogenesis via the METTL3 pathway and regulate VEGF-C expression via the METTL3/IGF2BP2-m6A pathway VEGF-C-mediated lymphangiogenesis via the METTL3/IGF2BP2-m6A pathway in DFU mice.

CONCLUSION

ADSCs enhance VEGFR3-mediated lymphangiogenesis via METTL3-mediated VEGF-C m6A modification to improve wound healing in DFUs, indicating that ADSCs may be regarded as a promising therapeutic strategy to promote wound healing in DFUs.

Adipose-Derived Stem Cell Conditioned Medium and Wound Healing: A Systematic Review

Adipose-derived stem cells (ASCs) have been growing in popularity for their potential in wound healing and tissue engineering. Stem cell therapies are limited in application, with the need to maintain cell viability and function as well as safety concerns. It has been increasingly reported that the effects of ASCs are predominantly attributable to the paracrine effects of the secreted factors, which can be collected in conditioned medium (CM). The goal of this systematic review is to investigate the effects on wound healing of CM collected from ASC culture. Original articles relevant to ASC-CM and wound healing (in vitro: dermal fibroblast, epidermal keratinocytes and their equivalent cell lines; in vivo: full-thickness wound models) were included. The agreement level of selections between two investigators were calculated by the kappa scores. And the information concerning to the publications, CM preparation and its application and effects were extracted and reported in a systematic way and summarized in tables. In total, 121 publications were initially identified through a search of the PubMed/MEDLINE database with a specific search algorithm, and 36 articles were ultimately included after two screenings. Nineteen were in vitro studies that met the search criteria and 17 were in vivo studies with or without in vitro data. In summary, based on the included articles, treatment with ASC conditioned medium (ASC-CM), to a large extent, resulted in positive effects on wound healing in vitro and in vivo. Modulation of the culture conditions of ASCs producing the CM, including hypoxic conditions, alternative substrates, medium supplementation, as well as genetic modification of cells, favorably promoted the effects of ASC-CM. Finally, a discussion of the future perspectives and therapeutic potential of ASC-CM, which also addresses the limitations of the field, is presented. A limitation of the evidence is the inconsistency in CM preparation methods among included articles. In conclusion, ASC-CM is a promising novel cell-free therapy for wound healing in regenerative medicine and warrants further exploration.

The glucagon-like peptide 1 receptor agonist Exendin-4 induces tenogenesis in human mesenchymal stem cells

Tendon injuries are common and account for up to 50% of musculoskeletal injuries in the United States. The poor healing nature of the tendon is attributed to poor vascularization and cellular composition. In the absence of FDA-approved growth factors for tendon repair, engineering strategies using bioactive factors, donor cells, and delivery matrices to promote tendon repair and regeneration are being explored. Growth factor alternatives in the form of small molecules, donor cells, and progenitors offer several advantages and enhance the tendon healing response. Small drug molecules and peptides offer stability over growth factors that are known to suffer from relatively short biological half-lives. The primary focus of this study was to assess the ability of the exendin-4 (Ex-4) peptide, a glucagon-like peptide 1 (GLP-1) receptor agonist, to induce tenocyte differentiation in bone marrow-derived human mesenchymal stem cells (hMSCs). We treated hMSCs with varied doses of Ex-4 in culture media to evaluate proliferation and tendonogenic differentiation. A 20 nM Ex-4 concentration was optimal for promoting cell proliferation and tendonogenic differentiation. Tendonogenic differentiation of hMSCs was evaluated via gene expression profile, immunofluorescence, and biochemical analyses. Collectively, the levels of tendon-related transcription factors (Mkx and Scx) and extracellular matrix (Col-I, Dcn, Bgn, and Tnc) genes and proteins were elevated compared to media without Ex-4 and other controls including insulin and IGF-1 treatments. The tendonogenic factor Ex-4 in conjunction with hMSCs appear to enhance tendon regeneration.

Human adipose-derived stem cells promote seawater-immersed wound healing via proangiogenic effects

Seawater immersion can increase the damage to skin wounds and produce chronic wounds, and the application of human adipose-derived stem cells can significantly promote healing. However, the mechanism underlying angiogenesis is currently unclear. In this study, we investigated the vascularization effect of human adipose-derived stem cells on the repair of seawater-treated skin wounds and explored the underlying mechanisms using bioinformatics. The results showed that human adipose-derived stem cells differentiated into vascular endothelial cells and promoted seawater-immersed wound vascularization by promoting vascular endothelial cell proliferation and migration. The differentially expressed genes between human adipose-derived stem cells and fibroblasts were identified and analyzed (including via gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment, protein–protein interaction network, and correlation analyses). The genes may promote wound healing by regulating the mechanisms of extracellular matrix remodeling, programmed cell death, inflammation, and vascularization. In conclusion, this study provides novel insights into the use of human adipose-derived stem cells in the regeneration of seawater-immersed skin wounds and chronic wounds.

Stromal cell-derived factor-1/Exendin-4 cotherapy facilitates the proliferation, migration and osteogenic differentiation of human periodontal ligament stem cells in vitro and promotes periodontal bone regeneration in vivo

Objectives

Stromal cell‐derived factor‐1 (SDF‐1) actively directs endogenous cell homing. Exendin‐4 (EX‐4) promotes stem cell osteogenic differentiation. Studies revealed that EX‐4 strengthened SDF‐1‐mediated stem cell migration. However, the effects of SDF‐1 and EX‐4 on periodontal ligament stem cells (PDLSCs) and bone regeneration have not been investigated. In this study, we aimed to evaluate the effects of SDF‐1/EX‐4 cotherapy on PDLSCs in vitro and periodontal bone regeneration in vivo.

Methods

Cell‐counting kit‐8 (CCK8), transwell assay, qRT‐PCR and western blot were used to determine the effects and mechanism of SDF‐1/EX‐4 cotherapy on PDLSCs in vitro. A rat periodontal bone defect model was developed to evaluate the effects of topical application of SDF‐1 and systemic injection of EX‐4 on endogenous cell recruitment, osteoclastogenesis and bone regeneration in vivo.

Results

SDF‐1/EX‐4 cotherapy had additive effects on PDLSC proliferation, migration, alkaline phosphatase (ALP) activity, mineral deposition and osteogenesis‐related gene expression compared to SDF‐1 or EX‐4 in vitro. Pretreatment with ERK inhibitor U0126 blocked SDF‐1/EX‐4 cotherapy induced ERK signal activation and PDLSC proliferation. SDF‐1/EX‐4 cotherapy significantly promoted new bone formation, recruited more CXCR4⁺ cells and CD90⁺/CD34^‐ stromal cells to the defects, enhanced early‐stage osteoclastogenesis and osteogenesis‐related markers expression in regenerated bone compared to control, SDF‐1 or EX‐4 in vivo.

Conclusions

SDF‐1/EX‐4 cotherapy synergistically regulated PDLSC activities, promoted periodontal bone formation, thereby providing a new strategy for periodontal bone regeneration.

Adipose-Derived Mesenchymal Stem Cells in the Treatment of Diabetic Foot Ulcers: A Review of Preclinical and Clinical Studies

This review provides an outline of the use of adipose-derived mesenchymal stem cells (AMSCs) in the treatment of diabetic foot ulcers (DFUs). A systematic search of PubMed and the Cochrane database was performed on October 2, 2019. Eighteen studies were identified (14 preclinical and 4 clinical). Studies in animal models have demonstrated that AMSCs enhance diabetic wound healing, accelerate granulation tissue formation, and increase reepithelialization and neovascularization. Only 1 randomized control trial has been published so far. Patients (n = 25) with DFUs were treated using an allogeneic AMSC directly on the wound bed as a primary dressing, and improvements were found in complete wound closure in the treatment group (n = 16). Three clinical studies showed that autologous AMSC might be a safe alternative to achieve therapeutic angiogenesis in patients with diabetes and peripheral arterial disease. Based on the available evidence, AMSCs hold promise in the treatment of DFUs. However, this evidence requires confirmation by well-designed trials. Additional studies are also required to understand some issues regarding this treatment for DFUs. For example, the potential application of autologous or allogeneic AMSCs in different types of DFUs, optimal dose/infusion schedules, safety evaluations, and cost-effectiveness.

Adipose stem cells from type 2 diabetic mice exhibit therapeutic potential in wound healing

Background

Diabetic patients suffer from impaired wound healing. Mesenchymal stem cell (MSC) therapy represents a promising approach toward improving skin wound healing through the release of soluble growth factors and cytokines that stimulate new vessel formation and modulate inflammation. Whether adipose tissue-derived MSCs (ASCs) from type 2 diabetes (T2D) donors are suitable for skin damage repair remains largely unknown.

Methods

In this study, we compared the phenotype and functionality of ASCs harvested from high-fat diet (HFD) and streptozotocin (STZ)-induced T2D or control mice, and assessed their abilities to promote wound healing in an excisional wound splinting mouse model with T2D.

Results

T2D ASCs expressed similar cellular markers as control ASCs but secreted less hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF), and transforming growth factor β (TGF-β). T2D ASCs were somewhat less effective in promoting healing of the wound, as manifested by slightly reduced re-epithelialization, cutaneous appendage regeneration, and collagen III deposition in wound tissues. In vitro, T2D ASCs promoted proliferation and migration of skin fibroblasts to a comparable extent as control ASCs via suppression of inflammation and macrophage infiltration.

Conclusions

From these findings, we conclude that, although ASCs from T2D mice are marginally inferior to control ASCs, they possess comparable therapeutic effects in wound healing.

Liraglutide-loaded PLGA/gelatin electrospun nanofibrous mats promote angiogenesis to accelerate diabetic wound healing via the modulation of miR-29b-3p

Diabetic wounds remain a serious clinical challenge whereas current therapies have limited effects on reducing the high disability and morbidity. Impaired vascularization is closely associated with delayed healing of diabetic wounds and liraglutide (Lira), a GLP-1R receptor agonist, has been reported to promote the angiogenic ability of endothelial cells. However, its application is hindered owing to the unsustainable drug concentration. In this study, we prepared a poly (lactic-co-glycolic acid)/gelatin (PLGA/Gel) nanofibrous mat scaffold to sustain the release of Lira for skin tissue engineering through 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxy sulfosuccinimide (EDC/NHS), a green cross-linking-graft integration method. The incorporation of Lira into PLGA/Gel increased the pore size, hydrophilicity, elasticity and degradation properties of nanofibrous mats, which were advantageous to wound healing. In addition, the effects on diabetic wound healing, vascularization and its underlying mechanism were evaluated. The results revealed that PLGA/Gel/Lira remarkably improved the healing efficiency of diabetic dermal wounds characterized by shortened wound closure time, increased blood vessel density, and elevated collagen deposition and alignment. In vitro, Lira reversed the inhibitory effects on proliferation, migration, tube differentiation, and VEGF secretion of endothelial cells induced by high glucose (HG). As for the underlying mechanism, Lira specifically decreased the level of miR-29b-3p, targeting the AKT/GSK-3β/β-catenin pathway to regulate the biological function of endothelial cells. In conclusion, for the first time this study combined PLGA/Gel with Lira to take advantage of their synergistic effects to promote vascularization, a promising strategy to accelerate diabetic wound repair.

The Treatment of Impaired Wound Healing in Diabetes: Looking among Old Drugs

Chronic wounds often occur in patients with diabetes mellitus due to the impairment of wound healing. This has negative consequences for both the patient and the medical system and considering the growing prevalence of diabetes, it will be a significant medical, social, and economic burden in the near future. Hence, the need for therapeutic alternatives to the current available treatments that, although various, do not guarantee a rapid and definite reparative process, appears necessary. We here analyzed current treatments for wound healing, but mainly focused the attention on few classes of drugs that are already in the market with different indications, but that have shown in preclinical and few clinical trials the potentiality to be used in the treatment of impaired wound healing. In particular, repurposing of the antiglycemic agents dipeptidylpeptidase 4 (DPP4) inhibitors and metformin, but also, statins and phenyotin have been analyzed. All show encouraging results in the treatment of chronic wounds, but additional, well designed studies are needed to allow these drugs access to the clinics in the therapy of impaired wound healing.

Biological activity of mesenchymal stem cells secretome as a basis for cell-free therapeutic approach

Mesenchymal stem (stromal) cells (MSCs) are self-renewing, cultured adult stem cells which secrete a complex set of multiple soluble biologically active molecules such as chemokines, and cytokines, cell adhesion molecules, lipid mediators, interleukins (IL), growth factors (GFs), hormones, micro RNAs (miRNAs), long non-coding RNAs (lncRNAs), messenger RNAs (mRNAs), exosomes, as well as microvesicles, the secretome. MSCs of various origin, including adipose-derived stem cells (ASCs), bone marrow derived mesenchymal stem cells (BM-MSCs), human uterine cervical stem cells (hUCESCs), may be good candidates for obtaining secretome-derived products. Different population of MSCs can secret different factors which could have anti-inflammatory, anti-apoptotic, anti-fibrotic activities, a neuroprotective effect, could improve bone, muscle, liver regeneration and wound healing. Therefore, the paracrine activity of conditioned medium obtained when cultivating MSCs, due to a plethora of bioactive factors, was assumed to have the most prominent cell-free therapeutic impact and can serve as a better option in the field of regenerative medicine in future.

Exendin-4 regulates endoplasmic reticulum stress to protect endothelial progenitor cells from high-glucose damage

BACKGROUND

High glucose affects the function of endothelial cells by increasing oxidative stress. Studies have found that exendin-4 can improve wound healing in diabetic mice and mice with normal blood glucose. However, the mechanism of exendin-4 in endothelial progenitor cells under high-glucose condition has not been fully elucidated.

METHODS

Diabetic mouse models were established to investigate the effects of exendin-4 on endothelial progenitor cells in diabetic mice. Serum superoxide dismutase (SOD) and malondialdehyde (MDA) were determined by WST-8 and thiobarbituric acid (TBA) colorimetry, respectively. Cell viability, apoptosis and reactive oxygen species (ROS) were detected by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and flow cytometry. Gene and protein expressions were determined by Quantitative reverse transcription PCR (qRT-PCR) assay and Western blot (WB).

RESULTS

The results showed that in diabetic mice, exendin-4 did not affect blood glucose or body weight, moreover, it improved aortic diastolic function, increased SOD activity and down-regulated malondialdehyde (MDA) level in the mice. In addition, exendin-4 also increased endothelial progenitor cell (EPCs) viability and reduced cell apoptosis through inhibiting p38 MAPK pathway and reducing endoplasmic reticulum stress and ROS.

CONCLUSION

Exndin-4 can alleviate diabetes-caused damage to mice, moreover, it reduced endoplasmic reticulum stress and ROS through inhibiting p38 MAPK pathway in MPCs cells under high-glucose condition, thus increasing cell viability and reducing cell apoptosis.

Human Adipose-Derived Stem Cells Promote Seawater-Immersed Wound Healing by Activating Skin Stem Cells via the EGFR/MEK/ERK Pathway

Seawater (SW) immersion can increase the damage of skin wounds and produce refractory wounds. However, few studies have been conducted to investigate the mechanisms of SW immersion on skin wounds. In our current study, we investigated the effect of human adipose-derived stem cells (hADSCs) on the repair of SW-treated full-thickness skin wounds and the underlying mechanisms. The results showed that SW immersion could reduce the expression of EGF and suppress the activation of the MEK/ERK signaling pathway. At the same time, the proliferation and migration of skin stem cells were inhibited by SW immersion, resulting in delayed wound healing. However, hADSCs significantly accelerated the healing of SW-immersed skin wounds by promoting cell proliferation and migration through the aforementioned mechanisms. Our results indicate a role for hADSCs in the repair of seawater-immersed skin wounds and suggest a potential novel treatment strategy for seawater-immersed wound healing.

Current Therapeutic Strategies in Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are the fastest growing chronic complication of diabetes mellitus, with more than 400 million people diagnosed globally, and the condition is responsible for lower extremity amputation in 85% of people affected, leading to high-cost hospital care and increased mortality risk. Neuropathy and peripheral arterial disease trigger deformities or trauma, and aggravating factors such as infection and edema are the etiological factors for the development of DFUs. DFUs require identifying the etiology and assessing the co-morbidities to provide the correct therapeutic approach, essential to reducing lower-extremity amputation risk. This review focuses on the current treatment strategies for DFUs with a special emphasis on tissue engineering techniques and regenerative medicine that collectively target all components of chronic wound pathology.

Stromal vascular fraction promotes migration of fibroblasts and angiogenesis through regulation of extracellular matrix in the skin wound healing process

Background

A refractory wound is a typical complication of diabetes and is a common outcome after surgery. Current approaches have difficulty in improving wound healing. Recently, non-expanded stromal vascular fraction (SVF), which is derived from mature fat, has opened up new directions for the treatment of refractory wound healing. The aim of the current study is to systematically investigate the impact of SVF on wound healing, including the rate and characteristics of wound healing, ability of fibroblasts to migrate, and blood transport reconstruction, with a special emphasis on their precise molecular mechanisms.

Methods

SVF was isolated by digestion, followed by filtration and centrifugation, and then validated by immunocytochemistry, a MTS proliferation assay and multilineage potential analysis. A wound model was generated by creating 6-mm-diameter wounds, which include a full skin defect, on the backs of streptozocin-induced hyperglycemic mice. SVF or human adipose-derived stem cell (hADSC) suspensions were subcutaneously injected, and the wounds were characterized over a 9-day period by photography and measurements. A scratch test was used to determine whether changes in the migratory ability of fibroblasts occurred after co-culture with hADSCs. Angiogenesis was observed with human umbilical vein endothelial cells. mRNA from fibroblasts, endotheliocyte, and skin tissue were sequenced by high-throughput RNAseq, and differentially expressed genes, and pathways, potentially regulated by SVF or hADSCs were bioinformatically analyzed.

Results

Our data show that hADSCs have multiple characteristics of MSC. SVF and hADSCs significantly improved wound healing in hyperglycemic mice. hADSCs improve the migratory ability of fibroblasts and capillary structure formation in HUVECs. SVF promotes wound healing by focusing on angiogenesis and matrix remodeling.

Conclusions

Both SVF and hADSCs improve the function of fibroblast and endothelial cells, regulate gene expression, and promote skin healing. Various mechanisms likely are involved, including migration of fibroblasts, tubulogenesis of endothelial cells through regulation of cell adhesion, and cytokine pathways.

Secretome of Adipose Tissue-Derived Stem Cells (ASCs) as a Novel Trend in Chronic Non-Healing Wounds: An Overview of Experimental In Vitro and In Vivo Studies and Methodological Variables

Wound healing is a complex process with a linear development that involves many actors in a multistep timeline commonly divided into four stages: Hemostasis, inflammation, proliferation, and remodeling. Chronic non-healing wounds fail to progress beyond the inflammatory phase, thus precluding the next steps and, ultimately, wound repair. Many intrinsic or extrinsic factors may contribute to such an occurrence, including patient health conditions, age-related diseases, metabolic deficiencies, advanced age, mechanical pressure, and infections. Great interest is being focused on the adipose tissue-derived stem cell’s (ASC) paracrine activity for its potential therapeutic impact on chronic non-healing wounds. In this review, we summarize the results of in vitro and in vivo experimental studies on the pro-wound healing effects of ASC-secretome and/or extracellular vesicles (EVs). To define an overall picture of the available literature data, experimental conditions and applied methodologies are described as well as the in vitro and in vivo models chosen in the reported studies. Even if a comparative analysis of the results obtained by the different groups is challenging due to the large variability of experimental conditions, the available findings are undoubtedly encouraging and fully support the use of cell-free therapies for the treatment of chronic non-healing wounds.

Epithelial defect repair in the auricle and auditory meatus by grafting with cultured adipose-derived mesenchymal stem cell aggregate-extracellular matrix

Background:

Several patients experience persistent otorrhea after a flawless surgical procedure because of insufficient epithelial healing. Several efforts, such as autologous tissue allograft and xenograft, have been made to halt otorrhea. However, a stable technology to induce temporal epithelial repair is yet to be established. Therefore, this study aims to investigate whether implantation of seeding adipose-derived mesenchymal stem cell (ADMSC) aggregates on extracellular matrix (ECM; herein, ADMSC aggregate-ECM) into damaged skin wound promotes skin regeneration.

Methods:

ADMSC aggregate-ECM was prepared using a previously described procedure that isolated ADMSCs from rabbits and applied to the auricle and auditory meatus wound beds of New Zealand white rabbits. Wound healing was assessed by general observation and hematoxylin and eosin (H&E) staining. Secretion of growth factor of the tissue was evaluated by western blotting. Two other groups, namely, ECM and control, were used. Comparisons of three groups were conducted by one-way analysis of variance analysis.

Results:

ADMSCs adhered tightly to the ECM and quickly formed cell sheets. At 2 weeks, general observation and H&E staining indicated that the wound healing rates in the ADMSC aggregate-ECM (69.02 ± 6.36%) and ECM (59.32 ± 4.10%) groups were higher than that in the control group (43.74 ± 12.15%; P = 0.005, P < 0.001, respectively) in ear auricle excisional wounds. At 7 weeks, The scar elevation index was evidently reduced in the ADMSC aggregate-ECM (2.08 ± 0.87) and ECM (2.31 ± 0.33) groups compared with the control group (4.06 ± 0.45; P < 0.001, P < 0.001, respectively). In addition, the scar elevation index of the ADMSC aggregate-ECM group reached the lowest rate 4 weeks in advance. In auditory meatus excisional wounds, the ADMSC aggregate-ECM group had the largest range of normal skin-like structure at 4 weeks. The ADMSC aggregate–ECM and ECM groups secreted increased amounts of growth factors that contributed to skin regeneration at weeks 1 and 2, respectively.

Conclusions:

ADMSC aggregate-ECM and ECM are effective repair materials for wound healing, especially ADMSC aggregate-ECM. This approach will provide a meaningful experimental basis for mastoid epithelium repair in subsequent clinical trials.

Effect of miR-19b on the protective effect of Exendin-4 on islet cells in non-obese diabetic mice

This study analyzed the effect of miR-19b on the protective effect of Exendin-4 on islet cells in non-obese diabetic (NOD) mice. Twenty-four NOD/LT mice were randomized, according to the random number table, into a control group (4 µg/kg•day), a low-dose group (2 µg/kg•day Exendin-4), a medium-dose group (4 µg/kg•day Exendin-4) and a high-dose group (8 µg/kg•day Exendin-4) (n=6), with miR-19b expression interfered (an interference group) except for the control group. RT-qPCR was used to detect interference results and different doses of Exendin-4 were given for 8 weeks of intervention after the interference. CD4⁺ and CD8⁺ cell levels were detected by flow cytometry, IL-2 and IL-10 levels in the peripheral blood by enzyme-linked immunosorbent assay, and the apoptosis rate of islet cells in the pancreatic tissue by TUNEL. After 4 and 8 weeks of Exendin-4 intervention, mice in the high-dose group had lower blood glucose level than the medium-dose group (P<0.05). The medium-dose group had lower CD4⁺ cell level than the high-dose group (P<0.05), while the medium-dose group had higher CD8⁺ cell level than the high-dose group (P<0.05). After 8 weeks of intervention, compared with the medium-dose group, the high-dose group had lower IL-2 level (P<0.05), but higher IL-10 level (P<0.05). After 8 weeks of intervention, the medium-dose group had a higher apoptosis rate than the high-dose group (P<0.05). In conclusion, the decrease in miR-19b expression can improve the therapeutic effect of Exendin-4 on NOD, control blood glucose effectively and improve inflammatory response and immune function, as well as reduce islet cell injury. The increase in the dose of Exendin-4 can further improve its therapeutic effect on NOD.

Generation of Functional Human Adipose Tissue in Mice from Primed Progenitor Cells

Adipose tissue (AT) is used extensively in reconstructive and regenerative therapies, but transplanted fat often undergoes cell death, leading to inflammation, calcification, and requirement for further revision surgery. Previously, we have found that mesenchymal progenitor cells within human AT can proliferate in three-dimensional culture under proangiogenic conditions. These cells (primed ADipose progenitor cells, PADS) robustly differentiate into adipocytes in vitro (ad-PADS). The goal of this study is to determine whether ad-PADS can form structured AT in vivo, with potential for use in surgical applications. Grafts formed from ad-PADS were compared to grafts formed from AT obtained by liposuction after implantation into nude mice. Graft volume was measured by microcomputed tomography scanning, and the functionality of cells within the graft was assessed by quantifying circulating human adiponectin. The degree of graft vascularization by donor or host vessels and the content of human or mouse adipocytes within the graft were measured using species-specific endothelial and adipocyte-specific quantitative real time polymerase chain reaction probes, and histochemistry with mouse and human-specific lectins. Our results show that ad-PADS grafted subcutaneously into nude mice induce robust vascularization from the host, continue to increase in volume over time, express the human adipocyte marker PLIN1 at levels comparable to human AT, and secrete increasing amounts of human adiponectin into the mouse circulation. In contrast, grafts composed of AT fragments obtained by liposuction become less vascularized, develop regions of calcification and decreased content of PLIN1, and secrete lower amounts of adiponectin per unit volume. Enrichment of liposuction tissue with ad-PADS improves vascularization, indicating that ad-PADS may be proangiogenic. Mechanistically, ad-PADS express an extracellular matrix gene signature that includes elements previously associated with small vessel development (COL4A1). Thus, through the formation of a proangiogenic environment, ad-PADS can form functional AT with capacity for long-term survival, and can potentially be used to improve outcomes in reconstructive and regenerative medicine.

Incretin-based therapy for diabetic ulcers: from bench to bedside

INTRODUCTION

Diabetic foot ulcers are a serious complication of diabetes and are associated with pain, disability, and poor quality of life. Incretin-based therapy is available for type-2 diabetes. Aside from glucose control, such treatment can impart numerous beneficial effects.

AREAS COVERED

This review summarizes the preclinical and clinical evidence supporting incretin-based treatment approaches for diabetic ulcers.

EXPERT OPINION

Incretin-based therapy may have a role in the treatment of diabetic foot ulcers; the benefits of such treatment arise from attenuation of inflammatory response, improvement of keratinocyte migration, induction of angiogenesis, and the enhancement of tissue remodeling. Large-scale clinical trials are required to determine the advantages of GLP-1 receptor agonists and DPP4 inhibitors. Future research on the topical application of incretin-based therapy is necessary. Such therapeutic approaches may provide new hope in improving the treatment of impaired diabetic foot ulcers.