The role of microRNAs in the healing of diabetic ulcers

MicroRNA miR-145-5p Inhibits Cutaneous Wound Healing by Targeting PDGFD in Diabetic Foot Ulcer

Diabetic foot ulcer (DFU) is one major, common and serious chronic complication of diabetes mellitus, which is characterized by high incidence, high risk, high burden, and high treatment difficulty and is a leading cause of disability and death in patients with diabetes. Long-term hyperglycemia can result in cellular dysfunction of fibroblasts, which play pivotal roles in wound healing. MicroRNAs (miRNAs) were reported to mediate the pathological processes of multiple diseases, including diabetic wound healing. This research aimed to investigate the functional role of miR-145-5p in high-glucose (HG)-exposed fibroblasts and in DFU mouse models. Human foreskin fibroblast cells (HFF-1) were stimulated by HG to induce cell injury. MiR-145-5p level in HG-stimulated HFF-1 cells was detected via RT-qPCR. The binding between miR-145-5p and PDGFD was validated by Luciferase reporter assay. The effects of the miR-145-5p/PDGFD axis on the viability, migration, and apoptosis of HG-exposed HFF-1 cells were determined by CCK-8, wound healing, and flow cytometry assays. DFU mouse models were subcutaneously injected at the wound edges with miR-145-5p inhibitor/mimics. Images of the wounds were captured on day 0 and 8 post-injection, and wound samples were collected after mice were sacrificed for histological analysis by H&E staining. HG decreased cell viability and increased miR-145-5p expression in HFF-1 cells in a dose- and time-dependent manner. MiR-145-5p downregulation promoted cell viability and migration and inhibited cell apoptosis of HG-stimulated HFF-1 cells, while miR-145-5p overexpression exerted an opposite effect on cell viability, migration, and apoptosis. PDGFD was a direct target gene of miR-145-5p, whose silencing reversed the influence of miR-145-5p downregulation on HG-induced cellular dysfunction of HFF-1 cells. Additionally, downregulating miR-145-5p facilitated while overexpressing miR-145-5p inhibited wound healing in DFU mouse models. MiR-145-5p level was negatively associated with PDGFD level in wound tissue samples of DFU mouse models. MiR-145-5p inhibition improves wound healing in DFU through upregulating PDGFD expression.

Key extracellular proteins and TF-miRNA co-regulatory network in diabetic foot ulcer: Bioinformatics and experimental insights

BACKGROUND

Diabetic foot ulcers (DFUs), a serious complication of diabetes, are associated with abnormal extracellular protein (EP) metabolism. The identification of key EPs and their regulatory networks is crucial for the understanding of DFU formation and development of effective treatments. In this study, a large-scale bioinformatics analysis was conducted to identify potential therapeutic targets and experimental validation was performed to ensure the reliability and biological relevance of the findings.

METHODS

Due to the comprehensive profiling of DFU samples provided by the GSE80178 dataset, we initially selected it to derive differentially expressed genes (DEGs) associated with DFU. Subsequently, utilizing the UniProt database and annotated EP list from the Human Protein Atlas annotation database, we screened for extracellular protein-related differentially expressed genes (EP-DEGs) due to their crucial role in the pathogenesis and healing of DFU. We examined EP-DEG pathway enrichment and protein-protein interaction networks, analyzed paired full-thickness skin tissue samples from 24 patients with DFUs and healthy controls, and performed polymerase chain reaction (PCR) experiments to validate candidate genes. Ultimately, we constructed a transcription factor (TF)-microRNA (miRNA)-hub gene co-regulatory network to explore upstream and downstream regulatory connections based on validated DEGs.

RESULTS

Four crucial candidate genes (FMOD, LUM, VCAN, and S100A12) were identified and verified via PCR analysis. The TF-miRNA-hub EP-DEG regulatory network contained the pivotal TFs TRIM28 and STAT3 and the miRNAs hsa-mir-20a-5p, hsa-miR-21, and hsa-miR-203.

CONCLUSION

The findings of this study advance our understanding of the pathology of DFU by defining key roles of specific EPs and elucidating a comprehensive regulatory network. These insights pave the way for novel approaches to improve DFU treatment outcomes.

Multiple novel functions of circular RNAs in diabetes mellitus

Circular RNAs (circRNAs), as an emerging group of non-coding RNAs (ncRNAs), have received the attention given evidence indicating that these novel ncRNAs are implicated in various biological processes. Due to the absence of 5' and 3' ends in circ-RNAs, their two ends are covalently bonded together, and they are synthesised from pre-mRNAs in a process called back-splicing, which makes them more stable than linear RNAs. There is accumulating evidence showing that circRNAs play a critical role in the pathogenesis of diabetes mellitus (DM). Moreover, it has been indicated that dysregulation of circRNAs has made them promising diagnostic biomarkers for the detection of DM. Recently, increasing attention has been paid to investigate the mechanisms underlying the DM process. It has been demonstrated that there is a strong correlation between the expression of circRNAs and DM. Hence, our aim is to discuss the crosstalk between circRNAs and DM and its complications.

Peptide RL-QN15 promotes wound healing of diabetic foot ulcers through p38 mitogen-activated protein kinase and smad3/miR-4482-3p/vascular endothelial growth factor B axis

Background

Wound management of diabetic foot ulcers (DFUs) is a complex and challenging task, and existing strategies fail to meet clinical needs. Therefore, it is important to develop novel drug candidates and discover new therapeutic targets. However, reports on peptides as molecular probes for resolving issues related to DFUs remain rare. This study utilized peptide RL-QN15 as an exogenous molecular probe to investigate the underlying mechanism of endogenous non-coding RNA in DFU wound healing. The aim was to generate novel insights for the clinical management of DFUs and identify potential drug targets.

Methods

We investigated the wound-healing efficiency of peptide RL-QN15 under diabetic conditions using in vitro and in vivo experimental models. RNA sequencing, in vitro transfection, quantitative real-time polymerase chain reaction, western blotting, dual luciferase reporter gene detection, in vitro cell scratches, and cell proliferation and migration assays were performed to explore the potential mechanism underlying the promoting effects of RL-QN15 on DFU repair.

Results

Peptide RL-QN15 enhanced the migration and proliferation of human immortalized keratinocytes (HaCaT cells) in a high-glucose environment and accelerated wound healing in a DFU rat model. Based on results from RNA sequencing, we defined a new microRNA (miR-4482-3p) related to the promotion of wound healing. The bioactivity of miR-4482-3p was verified by inhibiting and overexpressing miR-4482-3p. Inhibition of miR-4482-3p enhanced the migration and proliferation ability of HaCaT cells as well as the expression of vascular endothelial growth factor B (VEGFB). RL-QN15 also promoted the migration and proliferation ability of HaCaT cells, and VEGFB expression was mediated via inhibition of miR-4482-3p expression by the p38 mitogen-activated protein kinase (p38MAPK) and smad3 signaling pathways.

Conclusions

RL-QN15 is an effective molecule for the treatment of DFUs, with the underlying mechanism related to the inhibition of miR-4482-3p expression via the p38MAPK and smad3 signaling pathways, ultimately promoting re-epithelialization, angiogenesis and wound healing. This study provides a theoretical basis for the clinical application of RL-QN15 as a molecular probe in promoting DFU wound healing.

Healing profiles in patients with a chronic diabetic foot ulcer: An exploratory study with machine learning

Diabetic foot ulcers (DFU) are one of the most frequent and debilitating complications of diabetes. DFU wound healing is a highly complex process, resulting in significant medical, economic and social challenges. Therefore, early identification of patients with a high-risk profile would be important to adequate treatment and more successful health outcomes. This study explores risk assessment profiles for DFU healing and healing prognosis, using machine learning predictive approaches and decision tree algorithms. Patients were evaluated at baseline (T0; N = 158) and 2 months later (T1; N = 108) on sociodemographic, clinical, biochemical and psychological variables. The performance evaluation of the models comprised F1-score, accuracy, precision and recall. Only profiles with F1-score >0.7 were selected for analysis. According to the two profiles generated for DFU healing, the most important predictive factors were illness representations on T1 IPQ-B (IPQ-B ≤ 9.5 and < 10.5) and the DFU duration (≤ 13 weeks). The two predictive models for DFU healing prognosis suggest that biochemical factors are the best predictors of a favorable healing prognosis, namely IL-6, microRNA-146a-5p and PECAM-1 at T0 and angiopoietin-2 at T1. Illness perception at T0 (IPQ-B ≤ 39.5) also emerged as a relevant predictor for healing prognosis. The results emphasize the importance of DFU duration, illness perception and biochemical markers as predictors of  healing in chronic DFUs. Future research is needed to confirm and test the obtained predictive models.

Role of Increased miR-222-3p Expression in Peripheral Blood and Wound Marginal Tissues of Type 2 Diabetes Mellitus Patients with Diabetic Foot Ulcer

Purpose

To study the correlations of miR-222-3p expression in the peripheral blood and wound marginal tissues of type 2 diabetes mellitus (T2DM) patients with the onset of diabetic foot ulcer (DFU), as well as explore the clinical value possessed by miR-222-3p in the diagnosis and treatment outcomes of DFU.

Methods

The study included 70 T2DM patients who did not suffer foot ulcers (T2DM group), 146 T2DM patients who suffered foot ulcers (DFU group), as well as 70 normal controls (NC group). Quantitative real-time PCR determined the MiR-222-3p relative expression. Clinical features and risk factors regarding DFU were assessed. Multiple stepwise logistic regression analysis assisted in confirming whether miR-222-3p expression could serve for independently predicting the risk factors for DFU. ROC curve analysis evaluated the diagnostic value exhibited by miR-222-3p level against DFU.

Results

T2DM group exhibited an obviously higher MiR-222-3p expression relative to NC group [1.98 (0.98, 3.62) vs 0.92 (0.61, 1.87)] (P < 0.01), but DFU group exhibited an obviously higher miR-222-3p expression relative to T2DM group [5.61 (1.98, 10.24) vs 1.98 (0.98, 3.62)] (P < 0.01). Besides, miR-222-3p expression presented a negative correlation with DFU healing rate (P < 0.05). According to Kaplan-Meier survival curve analysis, the group with high miR-222-3p expression showed higher unhealed DFU cumulative rate relative to the group with low expression (log-rank, P = 0.011, 0.001, respectively). Multivariate logistic regression analysis confirmed that high miR-222-3p expressions could independently predict DFU risk (OR=3.85, 95% CI 1.18~12.37, P = 0.008). According to the ROC curve analysis, the AUC of miR-222-3p specific to DFU diagnosis reached 0.803, with the best sensitivity of 95.93% and best specificity of 96.27%.

Conclusion

The increased expression of miR-222-3p in the peripheral blood of T2DM patients is closely related to the occurrence of DFU. MiR-222-3p is a biomarker with potential clinical value in diagnosing and evaluating the prognosis of DFU.

Endogenous Biological Drivers in Diabetic Lower Limb Wounds Recurrence: Hypothetical Reflections

An impaired healing response underlies diabetic foot wound chronicity, frequently translating to amputation, disability, and mortality. Diabetics suffer from underappreciated episodes of post-epithelization ulcer recurrence. Recurrence epidemiological data are alarmingly high, so the ulcer is considered in "remission" and not healed from the time it remains epithelialized. Recurrence may result from the combined effects of behavioral and endogenous biological factors. Although the damaging role of behavioral, clinical predisposing factors is undebatable, it still remains elusive in the identification of endogenous biological culprits that may prime the residual scar tissue for recurrence. Furthermore, the event of ulcer recurrence still waits for the identification of a molecular predictor. We propose that ulcer recurrence is deeply impinged by chronic hyperglycemia and its downstream biological effectors, which originate epigenetic drivers that enforce abnormal pathologic phenotypes to dermal fibroblasts and keratinocytes as memory cells. Hyperglycemia-derived cytotoxic reactants accumulate and modify dermal proteins, reduce scar tissue mechanical tolerance, and disrupt fibroblast-secretory activity. Accordingly, the combination of epigenetic and local and systemic cytotoxic signalers induce the onset of "at-risk phenotypes" such as premature skin cell aging, dysmetabolism, inflammatory, pro-degradative, and oxidative programs that may ultimately converge to scar cell demise. Post-epithelialization recurrence rate data are missing in clinical studies of reputed ulcer healing therapies during follow-up periods. Intra-ulcer infiltration of epidermal growth factor exhibits the most consistent remission data with the lowest recurrences during 12-month follow-up. Recurrence data should be regarded as a valuable clinical endpoint during the investigational period for each emergent healing candidate.

Accelerated Wound Healing in Diabetic Rat by miRNA-185-5p and Its Anti-Inflammatory Activity

Aim

Addressing both inflammation and epithelialization during the treatment of diabetic foot ulcers is an important step, but current treatment options are limited. MiRNA has important prospects in the treatment of diabetic foot refractory wound ulcers. Previous studies have reported that miR-185-5p reduces hepatic glycogen production and fasting blood glucose levels. We herein hypothesized that miR-185-5p might play an important role in the field of diabetic foot wounds.

Materials and Methods

MiR-185-5p in skin tissue samples from patients with diabetic ulcers and diabetic rats were measured using quantitative real-time PCR (qRT-PCR). The streptozotocin-induced diabetes rat model (male Sprague-Dawley rats) for diabetic wound healing was conducted. The therapeutic potential was observed by subcutaneous injection of miR-185-5p mimic into diabetic rat wounds. The anti-inflammation roles of miR-185-5p on human dermal fibroblast cells were analyzed.

Results

We found that miR-185-5p is significantly downregulated in diabetic skin (people with DFU and diabetic rats) compared to controls. Further, in vitro upregulation of miR-185-5p decreased the inflammatory factors (IL-6, TNF-α) and intercellular adhesion molecule 1 (ICAM-1) of human skin fibroblasts under advanced glycation end products (AGEs). Meanwhile, the increase of miR-185-5p promoted cell migration. Our results also confirmed that the topical increase of miR-185-5p decreases diabetic wound p-nuclear factor-κB (p-NF-κB), ICAM-1, IL-6, TNF-α, and CD68 expression in diabetic wounds. MiR-185-5p overexpression boosted re-epithelization and expedited wound closure of diabetic rats.

Conclusion

MiR-185-5p accelerated wound healing of diabetic rats, reepithelization, and inhibited the inflammation of diabetic wounds in the healing process, a potentially new and valid treatment for refractory diabetic foot ulcers.

miRNAs as Biomarkers in Diabetes: Moving towards Precision Medicine

Diabetes mellitus (DM) is a complex metabolic disease with many specifically related complications. Early diagnosis of this disease could prevent the progression to overt disease and its related complications. There are several limitations to using existing biomarkers, and between 24% and 62% of people with diabetes remain undiagnosed and untreated, suggesting a large gap in current diagnostic practices. Early detection of the percentage of insulin-producing cells preceding loss of function would allow for effective therapeutic interventions that could delay or slow down the onset of diabetes. MicroRNAs (miRNAs) could be used for early diagnosis, as well as for following the progression and the severity of the disease, due to the fact of their pancreatic specific expression and stability in various body fluids. Thus, many studies have focused on the identification and validation of such groups or "signatures of miRNAs" that may prove useful in diagnosing or treating patients. Here, we summarize the findings on miRNAs as biomarkers in diabetes and those associated with direct cellular reprogramming strategies, as well as the relevance of miRNAs that act as a bidirectional switch for cell therapy of damaged pancreatic tissue and the studies that have measured and tracked miRNAs as biomarkers in insulin resistance are addressed.

Exosome-cargoed microRNAs: Potential therapeutic molecules for diabetic wound healing

Diabetic foot ulcers are one of the most common complications of diabetes, requiring repeated surgical intervention and leading to amputation. Owing to the lack of effective drugs, novel therapeutics need to be explored. Decreased angiogenic factors, endothelial cell dysfunction and vascular lumen stenosis impair angiogenesis in diabetic wounds. Exosome-cargoed microRNAs are emerging as pivotal regulators of angiogenesis during wound closure. Herein, we summarize the up-to-date knowledge of exosomal microRNAs in modulating angiogenesis and accelerating diabetic wound healing, as well as their targets and underlying mechanisms. Exosomal microRNAs could be therapeutics with negligible rejection complications and good compatibility to treat diabetic foot ulcers.

Wound dressings incorporating microRNAs: Innovative therapy for diabetic wound treatment

Diabetic wounds are the most critical complication in patients with diabetes, which often lead to hospitalization and limb amputations. Diabetic foot ulcers (DFU) is characterized by infections, prolonged inflammation, and a delayed wound healing process. Different types of medical procedures including surgical therapy, drug delivery, stem cell therapy, and wound dressings are used to manage DFU. Bioactive dressings such as hydrogels, nanofiber, and collagens are promising materials that can accelerate the healing process. The wound dressing materials can also be loaded with bioactive molecules like nucleic acids. MicroRNAs (miRNAs) are small non-coding RNA molecules that have recently emerged as regulators of impaired wound healing and could be a target for DFU treatment. miRNA therapeutics can be delivered to the wound region using different delivery systems such as exosomes and nanoparticles. These wound dressings have a high potential for treating diabetic wounds by topical delivery of certain miRNAs in a sustained release manner.

Quercetin: an effective polyphenol in alleviating diabetes and diabetic complications

Various studies, especially in recent years, have shown that quercetin has beneficial therapeutic effects in various human diseases, including diabetes. Quercetin has significant anti-diabetic effects and may be helpful in lowering blood sugar and increasing insulin sensitivity. Quercetin appears to affect many factors and signaling pathways involved in insulin resistance and the pathogenesis of type 2 of diabetes. TNFα, NFKB, AMPK, AKT, and NRF2 are among the factors that are affected by quercetin. In addition, quercetin can be effective in preventing and ameliorating the diabetic complications, including diabetic nephropathy, cardiovascular complications, neuropathy, delayed wound healing, and retinopathy, and affects the key mechanisms involved in the pathogenesis of these complications. These positive effects of quercetin may be related to its anti-inflammatory and anti-oxidant properties. In this article, after a brief review of the pathogenesis of insulin resistance and type 2 diabetes, we will review the latest findings on the anti-diabetic effects of quercetin with a molecular perspective. Then we will review the effects of quercetin on the key mechanisms of pathogenesis of diabetes complications including nephropathy, cardiovascular complications, neuropathy, delayed wound healing, and retinopathy. Finally, clinical trials investigating the effect of quercetin on diabetes and diabetes complications will be reviewed.

Increased Expression of miR-155 in Peripheral Blood and Wound Margin Tissue of Type 2 Diabetes Mellitus Patients Associated with Diabetic Foot Ulcer

PURPOSE

To investigate the correlations of miR-155 expression in the peripheral blood and wound margin tissue of patients with diabetic foot ulcer (DFU) and explore the clinical value of miR-155 as a potential biomarker for the diagnosis and treatment outcomes of DFU.

METHODS

Sixty newly diagnosed T2DM patients without DFU (T2DM group), 112 T2DM patients with DFU (DFU group), and 60 healthy controls (NC group) were included. MiR-155 levels in the peripheral blood and wound margin tissue were determined by quantitative real-time PCR, while clinical features and risk factors of DFU were explored. Multiple stepwise logistic regression analysis was used to determine whether miR-155 expression was an independent risk factor for DFU. The diagnostic effectiveness of miR-155 level on DFU was evaluated using ROC curve analysis.

RESULTS

A significant decrease in the expression level of miR-155 was observed in T2DM group compared with NC group (P < 0.05), while a markedly increased miR-155 expression level was noted in DFU group compared with T2DM group (P < 0.01). Moreover, there was a negative correlation between the expression levels of miR-155 with healing rate of DFU. Kaplan-Meier survival curve analysis showed that the cumulative rate of unhealed DFU in miR-155 high expression group is higher than that in miR-155 low expression group, both in peripheral blood and wound margin tissue (log rank, P = 0.004, P < 0.001, respectively). The multivariate logistic regression analysis confirmed that a high expression of miR-155 was an independent risk factor for DFU. The ROC curve analysis indicated that the AUC of miR-155 for the diagnosis of DFU was 0.794, with the optimum sensitivity being 96.82% and the optimum specificity of 95.93%.

CONCLUSION

The increased expression of miR-155 in peripheral blood of T2DM patients is closely related to the occurrence of DFU. MiR-155 is a potentially valuable biomarker for diagnosis and prognosis of DFU.

Down-Regulation of miR-138 Alleviates Inflammatory Response and Promotes Wound Healing in Diabetic Foot Ulcer Rats via Activating PI3K/AKT Pathway and hTERT

OBJECTIVE

To study the role of miR-138 on the repair of diabetic foot ulcer (DFU) and further to explore its possible mechanism.

MATERIALS AND METHODS

miR-138 inhibitor, IGF-1, LY294002 were used in DFU rat mode, and the mRNA expression of miR-138 was detected. HE staining was used to observe the histological changes of skin ulcer in rats. The level of inflammation, wound healing, and blood vessel formation-related factors were detected by ELISA and immunohistochemical. The expression of VEGF and PI3K/AKT pathway-related proteins were detected by Western blot. To further determine the underlying mechanism of miR-138 in the repair of DFU, telomerase inhibitor BIBR-1232 was used in HUVECs. Dual-luciferase assay was used to determine the target relationship between miR-138 and hTERT. CCK-8, transwell, and tube formation assays were conducted to observe the biological behavior of HUVECs. Inflammatory cytokines and PI3K/AKT pathway-related proteins were also measured by ELISA and Western blot.

RESULTS

The mRNA expression of miR-138 in DFU rat was increased and ulcer of diabetic foot rats was improved after silencing miR-138. The results of cellular bioactivity in vitro experiment were consistent with that in vivo. Meanwhile, after silencing miR-138, the level of inflammatory cytokines was decreased, while the level of anti-inflammatory and healing factors was increased in vivo and vitro. Moreover, the ratios of p-PI3K/PI3K and p-AKT/AKT were upregulated after treated with miR-138 inhibitor and miR-138 was negatively regulated the expression of hTERT. However, the inhibitory effect on inflammatory response and the promotion effect on wound healing of miR-138 inhibitor were reversed by LY294002 and BIBR-1232.

CONCLUSION

Down-regulation of miR-138 could alleviate inflammatory response and promote wound healing in DFU rats by activating PI3K/AKT pathway and hTERT.

Downregulation of hsa-miR-203 in peripheral blood and wound margin tissue by negative pressure wound therapy contributes to wound healing of diabetic foot ulcers

Negative pressure wound therapy (NPWT) has been widely used in the treatment of chronic wounds, including diabetic foot ulcers (DFU) as the severe manifestation of diabetic foot. Hsa-miR-203 is proven to be correlated with the severity of DFU. To investigate whether NPWT influences hsa-miR-203 levels in persons with DFU, we detected hsa-miR-203 levels in peripheral plasma and wound margin tissue from the following patients: type 2 diabetic (T2D) patients with DFU (DFU group), T2D patients without DFU (NDFU group), patients with chronic skin ulcer and normal glucose tolerance (SUC group), and healthy volunteers with normal glucose tolerance (NC group). All patients in SUC group received NPWT. As contrast, some of patients in DFU group received NPWT (NPWT group) while others chose routine dressing therapy (non-NPWT group). In vitro experiments were also performed to determine influences of negative pressure on cell proliferation and migration of HaCaT cells (human keratinocytes). Results showed that before NPWT, levels of hsa-miR-203 in peripheral plasma (P-miR-203) and wound margin tissue (T-miR-203) of DFU group were obviously increased compared to SUC group while expression of P-miR-203 decreased in NDFU group compared with NC group. After NPWT, levels of P-miR-203 and T-miR-203 in DFU and SUC group were significantly lower than before. Changes of P-miR-203 and T-miR-203 after NPWT were positively correlated with 4-week ulcer healing rate in NPWT and SUC group. In vitro, negative pressure lowered the expression of hsa-miR-203, enhancing cell proliferation and migration in HaCaT cells via up-regulation of p63 protein. Meanwhile, the effects of negative pressure on cells were remarkable reduced by high-glucose intervention. Our study suggests that NPWT promotes DFU healing by reducing the expression of hsa-miR-203 in peripheral blood and wound tissue. The changes of hsa-miR-203 in peripheral blood and wound tissue may be related to the therapeutic effect of NPWT.

Integrated analysis of tRNA-derived small RNAs reveals new therapeutic genes of hyperbaric oxygen in diabetic foot ulcers

Background: To reveal the alterations of tRNA-derived small RNA (tsRNA) expression profiles induced by hyperbaric oxygen (HBO) treatment in diabetic foot ulcers (DFUs) and investigate new therapeutic targets. Materials & methods: tsRNA sequencing was employed in normal skin tissue, in DFUs, and after HBO treatment groups. A quantitative real-time PCR was used to validate tsRNA sequencing results and their targets levels. Bioinformatics analysis was performed to reveal their therapeutic functions in DFUs. Results: A total of 22 tsRNAs were differentially expressed in the three groups. Three selected tsRNAs were validated by quantitative real-time PCR for further analysis, which were all significantly overexpressed in DFU while being normally expressed after HBO treatment. Bioinformatics analysis disclosed that these tsRNAs may play therapeutic roles through the regulation of the Wnt signaling pathway. Conclusion: tsRNAs may be novel useful targets for HBO to treat DFUs.

The Role of microRNAs in the Development of Type 2 Diabetes Complications

MicroRNAs represent a class of small (19-25 nucleotides) single-strand pieces of RNA that are noncoding ones. They are synthesized by RNA polymerase II from transcripts that fold back on themselves. They mostly act as gene regulatory agents that pair with complementary sequences on mRNA and produce silencing complexes, which, in turn, suppress coding genes at a post-transcriptional level. There is now evidence that microRNAs may affect insulin secretion or insulin action, as they can alter pancreatic beta cells development, insulin production, as well as insulin signaling. Any molecular disorder that affects these pathways can deteriorate insulin resistance and lead to type 2 diabetes mellitus (T2DM) onset. Furthermore, the expression of several microRNAs is up- or down-regulated in the presence of diabetic microvascular complications (i.e., peripheral neuropathy, nephropathy, retinopathy, foot ulcers), as well as in patients with coronary heart disease, stroke, and peripheral artery disease. However, more evidence is needed, specifically regarding T2DM patients, to establish the use of such microRNAs as diagnostical biomarkers or therapeutic targets in daily practice.

Enhanced Expression of miR-34c in Peripheral Plasma Associated with Diabetic Foot Ulcer in Type 2 Diabetes Patients

OBJECTIVE

To explore the correlation between the expression of miR-34c in peripheral blood of patients with type 2 diabetes mellitus (T2DM) and the onset of diabetic foot ulcer (DFU) and diabetic foot osteomyelitis (DFO).

METHODS

Sixty newly diagnosed patients with T2DM without DFU (T2DM group), 112 T2DM patients with DFU (DFU group) and 60 controls with normal glucose tolerance (NC group). The DFU group patients were subdivided into DFO (n=64) and NDFO (n=48) groups. Quantitative real-time PCR (qRT-PCR) method was used to determine miR-34c expression levels in the peripheral blood of subjects to analyze the clinical characteristics of DFU and DFO risk factors.

RESULTS

MiR-34c expression level in the T2DM group was marked higher than the NC group [2.99 (1.45-6.22) vs 1.01 (0.89-1.52)] (P < 0.05). However, the expression level of miR-34c in the DFU group was significantly higher than the T2DM group [9.65 (6.15-18.63) vs 2.99 (1.45-6.22)] (P < 0.01). Compared with the NDFO group, the expression level of miR-34c in the DFO group was also obviously increased [13.46 (8.89-19.11) vs 6.02 (5.93-14.72)] (P < 0.01). The expression level of miR-34c in DFU patients was positively correlated with the amputation rate of foot ulcers (P=0.030) and was negatively correlated with the healing rate of foot ulcers after eight weeks (P=0.025). Multifactorial logistic regression analysis showed that increased expression of miR-34c was an independent risk factor for DFU and DFO (OR_DFU=3.47, OR_DFO=4.25, P < 0.01). Meanwhile, the ROC curve analysis indicated that the AUC of miR-34c for the diagnosis of DFU and DFO was 0.803 and 0.904, the optimum sensitivity being was 100% and 98.7%, the optimum specificity was 98.4% and 98.4%, respectively.

CONCLUSION

The increased expression of miR-34c in peripheral blood of T2DM patients is closely related to the occurrence, development and prognosis of DFU and DFO.

Decreased expression of miR-24 in peripheral plasma of type 2 diabetes mellitus patients associated with diabetic foot ulcer

To examine the correlations of miR-24 expression in peripheral plasma with the onset of diabetic foot ulcer (DFU) and diabetic foot osteomyelitis (DFO) in type 2 diabetes mellitus (T2DM) patients and explore the clinical value of miR-24 as a potential biomarker for the diagnosis and treatment outcomes of DFU and DFO, a total of 60 newly diagnosed T2DM patients without DFU (T2DM group), 112 T2DM patients with DFU (DFU group), and 60 healthy controls (NC group) were included. DFU group were further divided into DFO group (n = 64) and non-DFO group (n = 48). MiR-24 levels were determined by quantitative real-time PCR, while clinical features and risk factors of DFU and DFO were explored. The expression level of miR-24 in T2DM and DFU group was significantly lower than in NC group (P < .05), and that in DFU group was significantly lower than in T2DM group (P < .01). Additionally, the level of miR-24 significantly decreased in DFO group compared to non-DFO group (P < .01). Moreover, it was negatively correlated with the amputation rate in DFU group (P = .043) and positively correlated with healing rate after 8 weeks (P = .036). The multivariate logistic regression analysis confirmed that a low expression of miR-24 was an independent risk factor for DFU and DFO. The ROC curve analysis indicated that the AUC of miR-24 for the diagnosis of DFU and DFO was 0.849 (95% CI, 0.618-0.879, P < .001) and 0.782 (95% CI, 0.595-0.813, P < .001). Thus, a decreased expression of miR-24 of T2DM patients was closely related to the occurrence, development and prognosis of DFU and DFO, suggesting the use of miR-24 as a potential biomarker for the prediction of DFU and DFO.

Adipose mesenchymal stem cell exosomes promote wound healing through accelerated keratinocyte migration and proliferation by activating the AKT/HIF-1α axis

Accelerating wound healing is a key consideration for surgeons. The three stages of wound healing include the inflammatory response, cell proliferation and tissue repair, and much research has focused on the migration and proliferation of epidermal cells, since this is one of the most important steps in wound healing. Studies have shown that adipose mesenchymal stem cells (ADSCs) can promote wound healing by releasing exosomes, although the specific mechanism remains unclear. To clarify the role of adipose mesenchymal stem cell exosomes (ADSCs-exo), we constructed a HaCaT cells model and a mouse wound healing model to examine the effects of ADSCs-exo on wound healing. CCK8 assays and the scratch test showed that ADSCs-exo could promote the proliferation and migration of HaCaT cells. Western blotting and real-time PCR showed that ADSCs-exo upregulated the phosphorylation of AKT and the expression of HIF-1α in HaCaT cells. HIF-1α expression was reduced by inhibiting AKT phosphorylation,and the migration of HaCaT cells simultaneously slowed. These results were also confirmed in vivo. In conclusion, we confirmed that ADSCs-exo promote the proliferation and migration of HaCaT cells by regulating the activation of the AKT/HIF-1α signaling pathway, thus promoting wound healing.

The role of microRNAs in the healing of diabetic ulcers

MicroRNAs (miRNAs) are small protected molecules with a length of 18 to 25 nucleotides. Many studies have recently been conducted on miRNAs, illustrating their role in regulating many biological, physiological, and pathological activities, such as maintaining cellular signalling and regulating cellular pathways. The main role of miRNAs is to regulate the expression of genes after translation, which can lead to the destruction or suppression of translation by binding to mRNAs. As any change in the regulation of miRNAs is associated with several physiological abnormalities, such as type 2 diabetes and its complications, these molecules can be used for therapeutic purposes or as biomarkers for the diagnosis of diseases such as diabetes and its complications. In this review article, we will discuss important findings about the miRNAs and the role of these molecules in different phases of the wound-healing process of chronic wounds, especially diabetic ulcer.