Microvascular dysfunction in diabetic foot disease and ulceration

Association of the triglyceride glucose index with sudden cardiac death in the patients with diabetic foot ulcer

BACKGROUND

This study examines the relationship between the TyG index and the risk of sudden cardiac death (SCD) in the patients with diabetic foot ulcer (DFU).

METHODS

688 type 2 diabetes mellitus (T2DM) inpatients with DFU between January 2010 and December 2023 was included in this retrospective study. The 1:1 propensity score matching (PSM) method was applied. The relationship between TyG index and SCD risk was analyzed using the Kaplan-Meier (K-M) survival curve analysis, multivariate Cox proportional hazard regression model, Restricted cubic spline (RCS) model analysis and subgroup analyses.

RESULTS

Over a median follow-up period of 61 months, 38 cases of SCD were recorded. After PSM, 71 pairs of score-matched patients according to TyG index were generated. K-M survival curves revealed higher SCD rates in patients with TyG index ≥9.65. The Cox proportional hazard model, independently associated with the risk of SCD (HR: 75.98; 95 % CI: 9.16 ∼ 630.40; P < 0.001). RCS model showed that SCD risk was non-linearly correlated with gradual increases in TyG index levels. Stratified analyses indicated a consistent relationship between increasing TyG index and SCD risk across all subgroups.

CONCLUSIONS

Elevated TyG index independently confers an increased risk for SCD in individuals with DFU.

Mechanisms of Impaired Wound Healing in Type 2 Diabetes: The Role of Epigenetic Factors

Despite decades of research, impaired extremity wound healing in type 2 diabetes remains a significant driver of patient morbidity, mortality, and health care costs. Advances in surgical and medical therapies, including the advent of endovascular interventions for peripheral artery disease and topical therapies developed to promote wound healing, have not reduced the frequency of lower leg amputations for nonhealing wounds in type 2 diabetes. This brief report is aimed at reviewing the roles of various cell types in tissue repair and summarizing the known dysfunctions of these cell types in diabetic foot ulcers. Recent advances in our understanding of the epigenetic regulation in immune cells identified to be altered in type 2 diabetes are summarized, and particular attention is paid to the developing research defining the epigenetic regulation of structural cells, including keratinocytes, fibroblasts, and endothelial cells. Gaps in knowledge are highlighted, and potential future directions are suggested based on the current state of the field.

Effect of Transcutaneous Application of Carbon Dioxide on Wound Healing, Wound Recurrence Rate and Diabetic Polyneuropathy in Patients with Neuropathic, Ischemic and Neuroischemic Diabetes-Related Foot Ulcers

(1) Background: Diabetes-related foot ulcers (DFUs) are a severe complication of diabetes mellitus (DM), with a five-year mortality rate of around 40%. Our study aimed to explore the effects of transcutaneous application of carbon dioxide (CO2 therapy) on DFU healing and recurrence rate, as well as diabetic polyneuropathy. (2) Methods: Adults with at least one chronic DFU were invited to undergo 20 50-min-long CO2 therapies within 4 weeks. After the completion of the last CO2 therapy, the effect of the therapies on wound healing and diabetic polyneuropathy was assessed, and 1 year later, we evaluated the incidence rate of DFU recurrence. (3) Results: Thirty-five subjects with DM and forty DFUs (ischemic: 15, neuropathic: 8, neuroischemic: 17) participated in our trial. After 4 weeks, 67.5% of all DFUs healed, whereas the reduction of the surface area of the unhealed wounds (74.0% ± 22.3%) was statistically significant. The restoration of protective sensations was also statistically significant. All unhealed wounds received standard care and healed within 2 additional weeks. The recurrence rate after 1 year was 17.5%. None of the patients required antibiotic treatment, hospitalization, or amputation. (4) Conclusion: CO2 therapy is a promising therapeutic intervention for treating DFUs and improving diabetic polyneuropathy.

Exploring air insole pressure and walking durations effects on microcirculation in healthy individuals to optimize diabetic foot ulcers prevention

To evaluate the impact of air insole on reducing the risk of diabetic foot ulcers (DFUs) in healthy individuals through microcirculation assessment, which considers blood flow as a critical factor due to the role of peripheral vascular disease in DFU development. The study analyzes the interaction between air insole pressure and walking duration. Repeated-measures design was used to assess the effects of two walking durations (10 and 20 min) and three air insole pressures (80, 160, and 240 mmHg), resulting in six walking conditions tested in 13 healthy participants. The average blood flow in the first metatarsal head (M1) was quantified using data from the last 3 min of the 10 min post-exercise period. The results of one-way ANOVA showed that the 80 mmHg air insole pressure was significantly lower microcirculation than 240 mmHg with 10 min walking duration (129.4 ± 9.1 vs 163.1 ± 12.6 PU, P = 0.035). The paired t-test showed three significant differences in the effects of the walking duration in all air insole pressures. (1) 10 min walking duration was significantly lower compared to 20 min with 80 mmHg air insole pressure (129.4 ± 9.1 vs 203.6 ± 10.1 PU, P = 0.001); (2) 10 min walking duration was significantly lower compared to 20 min with 160 mmHg air insole pressure (142.5 ± 10.6 vs 206.0 ± 12.5 PU, P = 0.001); (3) 10 min walking duration was significantly lower compared to 20 min with 240 mmHg (163.1 ± 12.6 vs 219.1 ± 11.8 PU, P = 0.008). This study highlights that walking with an air insole pressure of 80 mmHg for 20 minutes influences microcirculation at the first metatarsal head, potentially offering important benefits for individuals at risk of pressure-related injuries, such as DFUs.

Plant-Derived B-CGT Hydrogel Accelerates Diabetic Wound Healing Through Multitarget Modulation of Inflammation, Angiogenesis, and Tissue Remodeling

Diabetic wound healing presents significant challenges due to impaired angiogenesis, chronic inflammation, and cellular dysfunction. Building on previous research, this study further explores the potential of a plant-derived glucosyloxybenzyl 2-isobutylmalates (B-CGT) hydrogel in promoting diabetic wound healing. Network pharmacology and molecular docking analyses suggest that B-CGT may regulate key mechanisms, such as apoptosis, inflammation, and matrix remodeling, through core targets including SIRT1, CASP8, and MMP8. In vivo studies further demonstrated that B-CGT hydrogel significantly accelerated wound closure in diabetic mice, enhanced angiogenesis, promoted collagen deposition, and achieved immune balance by modulating macrophage polarization, thereby shifting the inflammatory environment toward a repair state. Moreover, B-CGT hydrogel significantly improved the wound microenvironment by upregulating VEGF expression and exerting antioxidant effects. By combining theoretical predictions with experimental validation, this study elucidates the multi-target synergistic regulatory mechanisms of B-CGT hydrogel. These findings provide new research directions for addressing immune imbalance and angiogenesis defects in diabetic wound healing and lay a scientific foundation for the optimization and application of chronic wound treatment strategies.

Deciphering Diabetic Foot Wounds: A Comprehensive Review on Classification, Multidrug Resistance, Microbial Insights, Management & Treatment Strategies, and Advanced Diagnostic Tools

Diabetic foot wounds and infections pose a significant and evolving challenge in diabetes care. Diabetic wound healing has become a major global concern for a very long time. Continuous research has been conducted to increase the healing process in diabetic ulcers to the rate of amputation. Wound healing is prolonged in diabetic patients due to various conditions, such as high glucose levels, neuropathy, poor blood circulation, and prolonged inflammation around the limbs, which causes the healing to be delayed compared to normal patients. Understanding the complexity of chronic foot wounds and the management and proper treatment would lead to a decrease in the risk of amputation. The medical team all over the world is constantly researching to lower the risk. This review paper offers a compelling journey through the multifaceted world of diabetic foot wounds and infections. It underscores the urgency of understanding classification, tackling multidrug resistance, and harnessing microbial insights to revolutionize the treatment and management of diabetic foot complications. Furthermore, it unveils state-of-the-art diagnostics, heralding a brighter future in the battle against this debilitating complication of diabetes.

Microcirculatory Dysfunction in Patients With Diabetes Mellitus Detected by a Distributed System of Wearable Laser Doppler Flowmetry Analysers

The paper is devoted to the study of perfusion and amplitude-frequency spectra of laser Doppler flowmetry (LDF) signals in patients with diabetes mellitus (DM) in different skin areas of the upper and lower extremities using a distributed system of wearable LDF analysers. LDF measurements were performed in the areas of the fingers, toes, wrists and shins. The mean perfusion values, the amplitudes of blood flow oscillations in endothelial, neurogenic, myogenic, respiratory and cardiac frequency ranges, and the values of nutritive blood flow were analysed. The results revealed a decrease in tissue perfusion and nutritive blood flow in the lower extremities and an increase in these parameters in the upper extremities in patients with DM. A decrease in the amplitudes of endothelial and neurogenic oscillations was observed. The obtained results confirm the possibility of using wearable LDF analysers to detect differences in the blood flow regulation in normal and pathological conditions.

Recurrence rates after healing in patients with neuroischemic diabetic foot ulcers healed with and without sucrose octasulfate-impregnated dressings: A 1-year comparative prospective study

To compare recurrence rates after a 1-year follow-up period of healed neuroischemic diabetic foot ulcers after treatment with or without sucrose octasulfate impregnated dressing. A 1-year prospective study with two arms was conducted between April 2021 and April 2023 on 92 patients with healed neuroischemic diabetic foot ulcers. Patients were divided into two groups; the treatment group, that includes patients healed with a sucrose octasulfate-impregnated dressing, and the control group, which includes patients treated with other local treatments different from sucrose octasulfate-impregnated dressings. After healing, patients were prospectively followed up during 1-year and assessed monthly in the specialised outpatient clinics. The main outcome of the study was ulcer recurrence after wound healing within 1 year follow-up. Secondary outcomes were minor or major amputation and all causes of death. Fifty patients in the treatment group and 42 patients in the control group were included. Fourteen (28%) patients suffered from a reulceration event in the treatment group compared to 28 (66.7%) in the control group, p < 0.001. Time to recurrence in the treatment group was 10 (16.26-2.75) and 11.50 (30.75-5.25) weeks in the control group, p = 0.464. There were no observed differences in the minor amputation rates between the two groups: 15.2% (n = 7) in the treatment group and 7.1% (n = 3) in the control group (p = 0.362). Major amputations and death outcomes were exclusively observed in the treatment group. Specifically, four major amputations (8.7%) in the treatment group were complications arising from recurring events complicated by infection during the SARS-CoV-2 period. Seven patients died due to complications not related with local therapy. The relative risk of recurrence was 20.18 times higher in the control group compared with those treated with octasulfate dressing (p < 0.001). Treatment with sucrose octasulfate-impregnated dressings can decrease recurrence rates of neuroischaemic diabetic foot ulcers more effectively than neutral dressings. Besides, it may enhance the foot's clinical properties in patients with poor microcirculation, which could aid in preventing future recurrences.

A fast all-optical 3D photoacoustic scanner for clinical vascular imaging

The clinical assessment of microvascular pathologies (in diabetes and in inflammatory skin diseases, for example) requires the visualization of superficial vascular anatomy. Photoacoustic tomography (PAT) scanners based on an all-optical Fabry-Perot ultrasound sensor can provide highly detailed 3D microvascular images, but minutes-long acquisition times have precluded their clinical use. Here we show that scan times can be reduced to a few seconds and even hundreds of milliseconds by parallelizing the optical architecture of the sensor readout, by using excitation lasers with high pulse-repetition frequencies and by exploiting compressed sensing. A PAT scanner with such fast acquisition minimizes motion-related artefacts and allows for the volumetric visualization of individual arterioles, venules, venous valves and millimetre-scale arteries and veins to depths approaching 15 mm, as well as for dynamic 3D images of time-varying tissue perfusion and other haemodynamic events. In exploratory case studies, we used the scanner to visualize and quantify microvascular changes associated with peripheral vascular disease, skin inflammation and rheumatoid arthritis. Fast all-optical PAT may prove useful in cardiovascular medicine, oncology, dermatology and rheumatology.

Vildagliptin promotes diabetic foot ulcer healing through autophagy modulation

The study aimed to investigate the molecular mechanisms underlying the effects of Vildagliptin on the healing of diabetic foot ulcers (DFUs). The research compared patients who received 12 weeks of Vildagliptin treatment to those who did not. Various molecular markers associated with wound healing were measured. Wound fluid samples were collected from DFUs using a filter paper absorption technique, and total RNA was extracted for quantitative real-time PCR (qPCR). The results showed that the autophagy marker NUP62 was significantly downregulated in the Vildagliptin group at week 12 compared to baseline (median expression 0.57 vs. 1.28; P = 0.0234). No significant change was observed in the placebo group (median expression 1.61 vs. 1.48; P = 0.9102). Both groups showed substantial downregulation of RIPK3, a necroptosis marker, at week 12 compared to their respective baselines. In addition to its effects on blood sugar levels, Vildagliptin may promote DFU healing by reducing autophagy in patients with diabetes.

Engineered exosomes as a prospective therapy for diabetic foot ulcers

Diabetic foot ulcer (DFU), characterized by high recurrence rate, amputations and mortality, poses a significant challenge in diabetes management. The complex pathology involves dysregulated glucose homeostasis leading to systemic and local microenvironmental complications, including peripheral neuropathy, micro- and macro-angiopathy, recurrent infection, persistent inflammation and dysregulated re-epithelialization. Novel approaches to accelerate DFU healing are actively pursued, with a focus on utilizing exosomes. Exosomes are natural nanovesicles mediating cellular communication and containing diverse functional molecular cargos, including DNA, mRNA, microRNA (miRNA), lncRNA, proteins, lipids and metabolites. While some exosomes show promise in modulating cellular function and promoting ulcer healing, their efficacy is limited by low yield, impurities, low loading content and inadequate targeting. Engineering exosomes to enhance their curative activity represents a potentially more efficient approach for DFUs. This could facilitate focused repair and regeneration of nerves, blood vessels and soft tissue after ulcer development. This review provides an overview of DFU pathogenesis, strategies for exosome engineering and the targeted therapeutic application of engineered exosomes in addressing critical pathological changes associated with DFUs.

Nanozymes for the Therapeutic Treatment of Diabetic Foot Ulcers

Diabetic foot ulcers (DFU) are chronic, refractory wounds caused by diabetic neuropathy, vascular disease, and bacterial infection, and have become one of the most serious and persistent complications of diabetes mellitus because of their high incidence and difficulty in healing. Its malignancy results from a complex microenvironment that includes a series of unfriendly physiological states secondary to hyperglycemia, such as recurrent infections, excessive oxidative stress, persistent inflammation, and ischemia and hypoxia. However, current common clinical treatments, such as antibiotic therapy, insulin therapy, surgical debridement, and conventional wound dressings all have drawbacks, and suboptimal outcomes exacerbate the financial and physical burdens of diabetic patients. Therefore, development of new, effective and affordable treatments for DFU represents a top priority to improve the quality of life of diabetic patients. In recent years, nanozymes-based diabetic wound therapy systems have been attracting extensive interest by integrating the unique advantages of nanomaterials and natural enzymes. Compared with natural enzymes, nanozymes possess more stable catalytic activity, lower production cost and greater maneuverability. Remarkably, many nanozymes possess multienzyme activities that can cascade multiple enzyme-catalyzed reactions simultaneously throughout the recovery process of DFU. Additionally, their favorable photothermal-acoustic properties can be exploited for further enhancement of the therapeutic effects. In this review we first describe the characteristic pathological microenvironment of DFU, then discuss the therapeutic mechanisms and applications of nanozymes in DFU healing, and finally, highlight the challenges and perspectives of nanozyme development for DFU treatment.

A case of pseudo-Kaposi sarcoma with chronic limb-threatening ischemia

BACKGROUND

Pseudo-Kaposi sarcoma (PKS) is a rare vascular proliferative disease, caused by arteriovenous malformation (AVM) and chronic venous insufficiency. The lesions are characterized by purple or reddish-brownish papules, plaques, and nodules. Although benign, it is clinically similar to Kaposi's sarcoma (KS), a malignant disease, and must be differentiated by histopathological examination. We report a rare case of PKS with chronic limb-threatening ischemia (CLTI).

CASE PRESENTATION

An 83-year-old man with diabetes mellitus (DM) presented to a local dermatology department with a complaint of a right second toe ulcer and was, thereby, referred to our department due to arterial bleeding during skin biopsy to exclude malignant diseases. Although the pulsation of dorsalis pedis artery of the affected limb was palpable, the skin perfusion pressure was only 20 and 30 mmHg on the dorsum and planter surface, respectively, indicating severe ischemia of toe and forefoot. Ultrasonography and computed tomography revealed an AVM around the right second metatarsophalangeal joint and occlusion of the right dorsalis pedis artery in the middle, indicating CLTI in the background. Pathological findings of the skin biopsy found capillary blood vessel proliferation, hemosiderin deposition, and extravascular red blood cell leakage in the dermal layer, which could be found in KS. However, CD34 was normally stained in the vascular endothelium, and human herpesvirus-8 staining was negative, resulting in the pathological diagnosis of PKS, a proliferative vascular lesion associated with AVM. The ulcer was spontaneously epithelialized, but 2 years later the ulcer recurred and infection developed, necessitating treatment for abnormal blood flow. Transarterial embolization using N-butyl 2-cyanoacrylate for the AVM controlled abnormal perfusion once; however, the procedure exacerbated perfusion of the toe, resulting in foot ulcer progression. Forefoot amputation with surgical excision of AVM was performed, and thereby, wound healing was achieved.

CONCLUSION

This is a rare case of PKS with CLTI complicated with AVM. As there is currently no established consensus on the treatment of PKS, the approach to treatment strategy should be tailored to the specific condition of each patient.

Machine Learning Analysis of Human Skin by Optoacoustic Mesoscopy for Automated Extraction of Psoriasis and Aging Biomarkers

Ultra-wideband raster-scan optoacoustic mesoscopy (RSOM) is a novel modality that has demonstrated unprecedented ability to visualize epidermal and dermal structures in-vivo. However, an automatic and quantitative analysis of three-dimensional RSOM datasets remains unexplored. In this work we present our framework: Deep Learning RSOM Analysis Pipeline (DeepRAP), to analyze and quantify morphological skin features recorded by RSOM and extract imaging biomarkers for disease characterization. DeepRAP uses a multi-network segmentation strategy based on convolutional neural networks with transfer learning. This strategy enabled the automatic recognition of skin layers and subsequent segmentation of dermal microvasculature with an accuracy equivalent to human assessment. DeepRAP was validated against manual segmentation on 25 psoriasis patients under treatment and our biomarker extraction was shown to characterize disease severity and progression well with a strong correlation to physician evaluation and histology. In a unique validation experiment, we applied DeepRAP in a time series sequence of occlusion-induced hyperemia from 10 healthy volunteers. We observe how the biomarkers decrease and recover during the occlusion and release process, demonstrating accurate performance and reproducibility of DeepRAP. Furthermore, we analyzed a cohort of 75 volunteers and defined a relationship between aging and microvascular features in-vivo. More precisely, this study revealed that fine microvascular features in the dermal layer have the strongest correlation to age. The ability of our newly developed framework to enable the rapid study of human skin morphology and microvasculature in-vivo promises to replace biopsy studies, increasing the translational potential of RSOM.

Biomaterials-Based Strategies to Enhance Angiogenesis in Diabetic Wound Healing

Amidst the present healthcare issues, diabetes is unique as an emerging class of affliction with chronicity in a majority of the population. To check and control its effects, there have been huge turnover and constant development of management strategies, and though a bigger part of the health care area is involved in achieving its control and the related issues such as the effect of diabetes on wound healing and care and many of the works have reached certain successful outcomes, still there is a huge lack in managing it, with maximum effect yet to be attained. Studying pathophysiology and involvement of various treatment options, such as tissue engineering, application of hydrogels, drug delivery methods, and enhancing angiogenesis, are at constantly developing stages either direct or indirect. In this review, we have gathered a wide field of information and different new therapeutic methods and targets for the scientific community, paving the way toward more settled ideas and research advances to cure diabetic wounds and manage their outcomes.

Skin microcirculatory responses: A potential marker for early diabetic neuropathy assessment using a low-cost portable diffuse optical spectrometry device

Diffuse optical measurement is an evolving optical modality providing a fast and portable solution for microcirculation assessment. Diffuse optics in static and dynamic modalities are combined here in a system to assess hemodynamics in skin tissues of control and diabetic subjects. The in-house developed system consists of a laser source, fiber optic probe, a low-cost avalanche photodiode, a finite element model (FEM) derived static optical property estimator, and a software correlator for continuous flow monitoring through microvasculature. The studies demonstrated that the system quantifies the changes in blood flow rate in the immediate skin subsurface. The system is calibrated with in vitro flow models and a proof-of-concept was demonstrated on a limited number of subjects in a clinical environment. The flow changes in response to vasoconstrictive and vasodilative stimuli were analyzed and used to classify different stages of diabetes, including diabetic neuropathy.

Renal function as risk factor for diabetic foot ulcers: A meta-analysis

The meta-analysis aimed to assess renal function (RF) as a risk factor for diabetic foot ulcers (DFUs). Using dichotomous or contentious random or fixed effect models, the outcomes of this meta-analysis were examined, and the odds Ratio (OR) and the mean difference (MD) with 95% confidence intervals (CIs) were computed. 16 examinations from 2004 to 2023 were enrolled for the present meta-analysis, including 808 914 individuals with diabetes mellitus (DM). DFU had significantly higher chronic renal failure (OR, 3.17; 95% CI, 1.97-5.09, p < 0.001), higher serum Creatinine (MD, 29.30; 95% CI, 9.68-48.92, p = 0.003), and a low estimated glomerular filtration rate (MD, -15.31; 95% CI, -19.36 to -11.26, p < 0.001) compared to non-DFU patients with DM. The examined data revealed that DFU had significantly higher chronic renal failure, higher serum Creatinine, and a low estimated glomerular filtration rate compared to non-DFU patients with DM. Yet, attention should be paid to its values since some comparisons had a low number of selected studies.

Performance of non-invasive bedside vascular testing in the prediction of wound healing or amputation among people with foot ulcers in diabetes: A systematic review

INTRODUCTION

The presence of peripheral artery disease (PAD) confers a significantly increased risk of failure to heal and major lower limb amputation for people with diabetes-related foot ulcer (DFU). Determining performance of non-invasive bedside tests for predicting likely DFU outcomes is therefore key to effective risk stratification of patients with DFU and PAD to guide management decisions. The aim of this systematic review was to determine the performance of non-invasive bedside tests for PAD to predict DFU healing, healing post-minor amputation, or need for minor or major amputation in people with diabetes and DFU or gangrene.

METHODS

A database search of Medline and Embase was conducted from 1980 to 30 November 2022. Prospective studies that evaluated non-invasive bedside tests in patients with diabetes, with and without PAD and foot ulceration or gangrene to predict the outcomes of DFU healing, minor amputation, and major amputation with or without revascularisation, were eligible. Included studies were required to have a minimum 6-month follow-up period and report adequate data to calculate the positive likelihood ratio (PLR) and negative likelihood ratio for the outcomes of DFU healing, and minor and major amputation. Methodological quality was assessed using the Quality in Prognosis Studies tool.

RESULTS

From 14,820 abstracts screened 28 prognostic studies met the inclusion criteria. The prognostic tests evaluated by the studies included: ankle-brachial index (ABI) in 9 studies; ankle pressures in 10 studies, toe-brachial index in 4 studies, toe pressure in 9 studies, transcutaneous oxygen pressure (TcPO2 ) in 7 studies, skin perfusion pressure in 5 studies, continuous wave Doppler (pedal waveforms) in 2 studies, pedal pulses in 3 studies, and ankle peak systolic velocity in 1 study. Study quality was variable. Common reasons for studies having a moderate or high risk of bias were poorly described study participation, attrition rates, and inadequate adjustment for confounders. In people with DFU, toe pressure ≥30 mmHg, TcPO2 ≥25 mmHg, and skin perfusion pressure of ≥40 mmHg were associated with a moderate to large increase in pretest probability of healing in people with DFU. Toe pressure ≥30 mmHg was associated with a moderate increase in healing post-minor amputation. An ABI using a threshold of ≥0.9 did not increase the pretest probability of DFU healing, whereas an ABI <0.5 was associated with a moderate increase in pretest probability of non-healing. Few studies investigated amputation outcomes. An ABI <0.4 demonstrated the largest increase in pretest probability of a major amputation (PLR ≥10).

CONCLUSIONS

Prognostic capacity of bedside testing for DFU healing and amputation is variable. A toe pressure ≥30 mmHg, TcPO2 ≥25 mmHg, and skin perfusion pressure of ≥40 mmHg are associated with a moderate to large increase in pretest probability of healing in people with DFU. There are little data available evaluating the prognostic capacity of bedside testing for healing after minor amputation or for major amputation in people with DFU. Current evidence suggests that an ABI <0.4 may be associated with a large increase in risk of major amputation. The findings of this systematic review need to be interpreted in the context of limitations of available evidence, including varying rates of revascularisation, lack of post-revascularisation bedside testing, and heterogenous subpopulations.

Improved small vessel visibility in diabetic foot arteriography using dual-energy CT

AIM

To test the feasibility and performance of dual-energy computed tomography (DECT) in foot arteriography of diabetic patients, where contrast medium is largely reduced within the small vessels.

MATERIALS AND METHODS

A total of 50 diabetic patients were enrolled prospectively, where DECT was acquired immediately after the CT angiography (CTA, group A) of the lower extremity. Two images were derived from the DECT data, one optimal virtual monochromatic image (VMI, group B) and one fusion image (group C), both of which were compared against the CTA image for visualising the foot arteries. The contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were evaluated. The arterial course and contrast were graded each using a five-point scale. The clarity of small vessel depiction was quantified by comparing the number of plantar metatarsal arteries found in the maximum intensity projection image.

RESULTS

The median CNRs and SNRs obtained in group B were approximately 45% and 20% higher than those in groups A and C, respectively (p<0.05). Group B also received higher subjective scores on the posterior tibial artery and the foot arteries (all >3) than groups A and C. The number of visible branches of the plantar metatarsal arteries was found to be substantially higher (p<0.05) in group B (median=6) than in groups A (median=2) and C (median=4).

CONCLUSION

DECT was found to be superior to conventional CTA in foot arteriography, and beyond the lower extremity, it might be a general favourable solution for imaging regions with small vessels and reduced contrast medium.

Research progress on the mechanism of angiogenesis in wound repair and regeneration

Poor wound healing and pathological healing have been pressing issues in recent years, as they impact human quality of life and pose risks of long-term complications. The study of neovascularization has emerged as a prominent research focus to address these problems. During the process of repair and regeneration, the establishment of a new vascular system is an indispensable stage for complete healing. It provides favorable conditions for nutrient delivery, oxygen supply, and creates an inflammatory environment. Moreover, it is a key manifestation of the proliferative phase of wound healing, bridging the inflammatory and remodeling phases. These three stages are closely interconnected and inseparable. This paper comprehensively integrates the regulatory mechanisms of new blood vessel formation in wound healing, focusing on the proliferation and migration of endothelial cells and the release of angiogenesis-related factors under different healing outcomes. Additionally, the hidden link between the inflammatory environment and angiogenesis in wound healing is explored.

Diabetic microvascular disease in non-classical beds: the hidden impact beyond the retina, the kidney, and the peripheral nerves

Diabetes microangiopathy, a hallmark complication of diabetes, is characterised by structural and functional abnormalities within the intricate network of microvessels beyond well-known and documented target organs, i.e., the retina, kidney, and peripheral nerves. Indeed, an intact microvascular bed is crucial for preserving each organ's specific functions and achieving physiological balance to meet their respective metabolic demands. Therefore, diabetes-related microvascular dysfunction leads to widespread multiorgan consequences in still-overlooked non-traditional target organs such as the brain, the lung, the bone tissue, the skin, the arterial wall, the heart, or the musculoskeletal system. All these organs are vulnerable to the physiopathological mechanisms that cause microvascular damage in diabetes (i.e., hyperglycaemia-induced oxidative stress, inflammation, and endothelial dysfunction) and collectively contribute to abnormalities in the microvessels' structure and function, compromising blood flow and tissue perfusion. However, the microcirculatory networks differ between organs due to variations in haemodynamic, vascular architecture, and affected cells, resulting in a spectrum of clinical presentations. The aim of this review is to focus on the multifaceted nature of microvascular impairment in diabetes through available evidence of specific consequences in often overlooked organs. A better understanding of diabetes microangiopathy in non-target organs provides a broader perspective on the systemic nature of the disease, underscoring the importance of recognising the comprehensive range of complications beyond the classic target sites.

Does the advantage of transcutaneous oximetry measurements in diabetic foot ulcer apply equally to free flap reconstruction?

BACKGROUND

Transcutaneous oxygen pressure (TcpO₂) is a precise method for determining oxygen perfusion in wounded tissues. The device uses either electrochemical or optical sensors.

AIM

To evaluate the usefulness of TcpO₂ measurements on free flaps (FFs) in diabetic foot ulcers (DFUs).

METHODS

TcpO₂ was measured in 17 patients with DFUs who underwent anterolateral thigh (ALT)-FF surgery and compared with 30 patients with DFU without FF surgery.

RESULTS

Significant differences were observed in the ankle-brachial index; duration of diabetes; and haemoglobin, creatinine, and C-reactive protein levels between the two groups. TcpO₂ values were similar between two groups except on postoperative days 30 and 60 when the values in the ALT-FF group remained < 30 mmHg and did not increase > 50 mmHg.

CONCLUSION

Even if the flap is clinically stable, sympathectomy due to adventitia stripping during anastomosis and arteriovenous shunt progression due to diabetic polyneuropathy could lead to low TcpO₂ values in the ALT-FF owing to its thick fat tissues, which is supported by the slow recovery of the sympathetic tone following FF. Therefore, TcpO₂ measurements in patients with DFU who underwent FF reconstruction may be less accurate than in those who did not.

Wireless Dynamic Light Scattering Sensors Detect Microvascular Changes Associated With Ageing and Diabetes

This article presents clinical results of wireless portable dynamic light scattering sensors that implement laser Doppler flowmetry signal processing. It has been verified that the technology can detect microvascular changes associated with diabetes and ageing in volunteers. Studies were conducted primarily on wrist skin. Wavelet continuous spectrum calculation was used to analyse the obtained time series of blood perfusion recordings with respect to the main physiological frequency ranges of vasomotions. In patients with type 2 diabetes, the area under the continuous wavelet spectrum in the endothelial, neurogenic, myogenic, and cardio frequency ranges showed significant diagnostic value for the identification of microvascular changes. Aside from spectral analysis, autocorrelation parameters were also calculated for microcirculatory blood flow oscillations. The groups of elderly volunteers and patients with type 2 diabetes, in comparison with the control group of younger healthy volunteers, showed a statistically significant decrease of the normalised autocorrelation function in time scales up to 10 s. A set of identified parameters was used to test machine learning algorithms to classify the studied groups of young controls, elderly controls, and diabetic patients. Our conclusion describes and discusses the classification metrics that were found to be most effective.

m6A epitranscriptomic modification in diabetic microvascular complications

N6-methyladenosine (m6A) modifications are modulated by m6A methyltransferases, m6A demethylases, and m6A-binding proteins. The dynamic and reversible patterns of m6A modification control cell fate programming by regulating RNA splicing, translation, and decay. Emerging evidence demonstrates that m6A modification of coding and noncoding RNAs exerts crucial effects that influence the pathogenesis of diabetic microvascular complications that include diabetic cardiomyopathy, diabetic nephropathy, diabetic retinopathy, diabetic neuropathy, and diabetic dermatosis. In this review, we summarize the roles of m6A modification and m6A modification-related enzymes in diabetic microvascular complications and discuss potential m6A modification-related enzyme-targeting therapeutic strategies.

Circulating Angiogenic Factors and Ischemic Diabetic Foot Syndrome Advancement-A Pilot Study

Despite clear evidence of inadequate angiogenesis in ischemic diabetic foot syndrome (DFS) pathogenesis, angiogenic factor level changes in patients with ischemic DFS remain inconsistent. This study aimed to assess circulating angiogenic factors concerning ischemic DFS advancement and describe their relationships with patients' clinical characteristics, microvascular parameters, and diabetic control. The study included 41 patients with ischemic DFS (67.3 (8.84) years; 82.9% males). Angiogenic processes were assessed by identifying circulating concentrations of five pro- and two anti-angiogenic factors. We found that penetrating ulcers were related to a significantly higher FGF-2 level (8.86 (5.29) vs. 5.23 (4.17) pg/mL, p = 0.02). Moreover, plasma FGF-2 showed a significant correlation with the SINBAD score (r = 0.32, p = 0.04), platelet count (r = 0.43, p < 0.01), white cell count (r = 0.42, p < 0.01), and age (r = -0.35, p = 0.03). We did not observe any significant linear relationship between the studied biomarkers and microcirculatory parameters, nor for glycemic control. In a univariate analysis using logistic regression, an increase in plasma FGF-2 was tied to greater odds of high-grade ulcers (OR 1.16; 95% CI 1.02-1.38, p = 0.043). This suggests that circulating FGF-2 may serve as a potential biomarker for predicting DFU advancement and progression. It is necessary to conduct further studies with follow-up observations to confirm this hypothesis.

Comparison of resting/postexercise ankle-brachial index and transcutaneous partial pressure of oxygen for noninvasive diagnosis of peripheral artery disease in type 2 diabetes mellitus

Background Type 2 diabetes

Type 2 diabetes mellitus (T2DM) is a strong risk factor for peripheral artery disease (PAD) and PAD diagnosis in T2DM may indicate coexisting coronary artery disease as well. Postexercise ankle brachial index (ABI) and transcutaneous partial pressure of oxygen (TcPO2) have not been evaluated for PAD diagnosis among Indian T2DM patients. This study aimed to evaluate the performance of resting + postexercise(R + PE) ABI and R + PE-TcPO2 for PAD diagnosis among T2DM patients at increased PAD risk, using colour duplex ultrasound (CDU) as reference standard.

Methods

This prospectively conducted diagnostic accuracy study involved T2DM patients at increased PAD risk. R-ABI≤0.9 or PE-ABI decline >20% from resting value in those with R-ABI between 0.91 and 1.4, R-TcPO2 <30 mm Hg or PE decline of TcPO2 to <30 mm Hg in those with R-TcPO2 ≥30 mm Hg, CDU showing >50% stenosis or complete occlusion of lower extremity arteries constituted PAD.

Results

Among 168 patients enrolled, R + PE-ABI diagnosed PAD in 19(11.3%), R + PE-TcPO2 in 61 (36.3%) and 17 (≈10%) had PAD finally confirmed by CDU. Sensitivity, specificity, PPV and NPV of R + PE-ABI for PAD diagnosis were 82.3%, 96.7%, 73.7% and 98% and that of R + PE-TcPO2 were 76.5%, 68.2%, 21.3% and 96.2%, respectively. PE-ABI increased the sensitivity of ABI by ≈ 18% and had 100% PPV for PAD. When both ABI and TcPO2 (R + PE tests) were normal, PAD could be safely excluded in 88% of patients.

Conclusion

PE-ABI should be routinely employed and TcPO2(R/PE) is unreliable as a stand-alone test for PAD detection among moderate to high risk T2DM patients.

Current and future outlook of loaded components in hydrogel composites for the treatment of chronic diabetic ulcers

Due to recalcitrant microangiopathy and chronic infection, traditional treatments do not easily produce satisfactory results for chronic diabetic ulcers. In recent years, due to the advantages of high biocompatibility and modifiability, an increasing number of hydrogel materials have been applied to the treatment of chronic wounds in diabetic patients. Research on composite hydrogels has received increasing attention since loading different components can greatly increase the ability of composite hydrogels to treat chronic diabetic wounds. This review summarizes and details a variety of newly loaded components currently used in hydrogel composites for the treatment of chronic diabetic ulcers, such as polymer/polysaccharides/organic chemicals, stem cells/exosomes/progenitor cells, chelating agents/metal ions, plant extracts, proteins (cytokines/peptides/enzymes) and nucleoside products, and medicines/drugs, to help researchers understand the characteristics of these components in the treatment of diabetic chronic wounds. This review also discusses a number of components that have not yet been applied but have the potential to be loaded into hydrogels, all of which play roles in the biomedical field and may become important loading components in the future. This review provides a "loading component shelf" for researchers of composite hydrogels and a theoretical basis for the future construction of "all-in-one" hydrogels.

Paradoxical Changes of Cutaneous Microcirculation and Sympathetic Fibers of Rat Hind Limbs after Sciatic Nerve Compression

BACKGROUND

Recent studies show evidence that surgical nerve decompression could improve cutaneous blood flow (CBF), which might benefit ulcer healing. However, the change of CBF and sympathetic fibers after nerve compression is poorly understood. In the current study, a unilateral sciatic nerve compression model was created in Sprague-Dawley rats.

METHODS

A laser Doppler imaging system was applied to assess the CBF of the regions below the ankles. Immunohistochemistry and transmission electron microscopy were used to investigate the histopathologic changes of sympathetic fibers in sciatic nerve samples.

RESULTS

Laser Doppler imaging revealed decreased CBF of both the lesional limb and the contralesional limb, which occurred earlier in the lesional side, indicating an enhanced sympathetic tone on vasomotor function. Intraneural density of sympathetic fibers decreased on both sides and the ultrastructure of unmyelinated fibers of both sides degenerated in a nonsynchronized manner.

CONCLUSIONS

The study revealed nonsynchronized reduced CBF of bilateral hind limbs with paradoxically degenerated and diminished sympathetic fibers in bilateral sciatic nerves after unilateral sciatic nerve compression. These results may validate the importance of and broaden the indications for surgical nerve decompression in preventing or treating foot ulcers.

Microcirculation Improvement in Diabetic Foot Patients after Treatment with Sucrose Octasulfate-Impregnated Dressings

To assess the patients' microcirculation evolution during the treatment with a sucrose octasulfate-impregnated dressing, fifty patients with neuroischaemic DFU treated with TLC-NOSF dressing were included in a prospective study between November 2020 and February 2022. TcpO₂ values were measured on the dorsalis pedis or tibial posterior arteries' angiosome according to the ulcer location. TcpO₂ values were assessed at day 0 and every 4 weeks during 20 weeks of the follow-up or until the wound healed. A cut-off point of tcpO₂ < 30 mmHg was defined for patients with impaired microcirculation. The TcpO₂ values showed an increase between day 0 and the end of the study, 33.04 ± 12.27 mmHg and 40.89 ± 13.06 mmHg, respectively, p < 0.001. Patients with impaired microcirculation showed an increase in the tcpO₂ values from day 0 to the end of the study (p = 0.023). Furthermore, we observed a significant increase in the TcpO₂ values in the forefoot DFU (p = 0.002) and in the rearfoot DFU (p = 0.071), with no difference between the ulcer locations (p = 0.694). The local treatment with TLC-NOSF dressing improved the microcirculation in patients with neuroischaemic DFU, regardless of microcirculation status at the baseline, and in the forefoot, regardless of the location.

Determination of light pressing pressure for improving foot skin blood flow in type 2 diabetic patients

OBJECTIVE

Traditional Thai massage is one of the alternative treatments for diabetic feet. However, the specific amount of pressing pressure applied to the foot during Thai foot massage is unknown. This study aimed to evaluate the effect of light pressing pressure on foot skin blood flow in type 2 diabetic patients.

METHODES

A single-arm repeated measures was conducted. Forty-three participants were recruited via the subjective examination and screening using the Michigan Neuropathy Screening Instrument. To obtain foot skin blood flow by laser doppler blood flowmetry, a probe was pasted on the 1st distal phalange of the big toe. Light pressure at a single point was applied on the plantar skin fold between the bases of the second and third toes by using the digital algometer. The pressure was applied gently, then increased slightly until the participant started to feel some minor discomfort. Patients were asked to rate their pain intensity using the visual analogue scale.

RESULTS

The average pressing pressure without discomfort was 3.55 ± 1.04 kg/cm². The foot skin blood flow increased significantly immediately after the pressing pressure, and this increase represented about 1.9 times when compared with the baseline (p < 0.001).

CONCLUSION

The application of light pressing pressure could be used as a basic standard criterion for massage to improve the foot skin blood flow in type 2 diabetic patients.

Monitoring and recovery of hyperglycaemia-induced endothelial dysfunction with rheopheresis in diabetic lower extremity ulceration with hyperviscosity

AIMS

Rheopheresis is an extracorporeal haematotherapy that improves haemorheological status by filtering proteins that enhance blood viscosity. It also has anti-inflammatory effects by removing inflammatory cytokines. Our study aims to examine the effects of rheopheresis on the endothelial status in diabetic lower extremity ulceration.

METHODS

In vitro experiments were performed in a HUVEC model to mimic hyperglycaemic stress. We determined the changes in gene expression levels of IL-6, IL-8, TNF-alpha, endothelin convertase enzyme, ET-1, and NO synthase, as well as the ROS and intracellular GSH levels upon hyperglycaemia. In in vivo studies, two rheopheresis procedures were performed on seven patients with diabetic lower extremity ulceration with hyperviscosity, and we measured the changes in plasma concentrations of ET-1, TXB2, SOD enzyme activity, and extracellular components of the glutathione pool depending on treatments.

RESULTS

Our results showed that hyperglycaemia increases endothelial expression of inflammatory cytokines, ET-1, and endothelin convertase enzyme, while NO synthase was decreased. As a result of rheopheresis, we observed decreased ET-1 and TXB2 concentrations in the plasma and beneficial changes in the parameters of the glutathione pool.

CONCLUSION

To summarize our results, hyperglycaemia-induced oxidative stress and endothelial inflammation can be moderated by rheopheresis in diabetic lower extremity ulceration with hyperviscosity.

The Efficacy of Exercise Training for Cutaneous Microvascular Reactivity in the Foot in People with Diabetes and Obesity: Secondary Analyses from a Randomized Controlled Trial

It is unclear if cutaneous microvascular dysfunction associated with diabetes and obesity can be ameliorated with exercise. We investigated the effect of 12-weeks of exercise training on cutaneous microvascular reactivity in the foot. Thirty-three inactive adults with type 2 diabetes and obesity (55% male, 56.1 ± 7.9 years, BMI: 35.8 ± 5, diabetes duration: 7.9 ± 6.3 years) were randomly allocated to 12-weeks of either (i) moderate-intensity continuous training [50−60% peak oxygen consumption (VO2peak), 30−45 min, 3 d/week], (ii) low-volume high-intensity interval training (90% VO2peak, 1−4 min, 3 d/week) or (iii) sham exercise placebo. Post-occlusive reactive hyperaemia at the hallux was determined by laser-Doppler fluxmetry. Though time to peak flux post-occlusion almost halved following moderate intensity exercise, no outcome measure reached statistical significance (p > 0.05). These secondary findings from a randomised controlled trial are the first data reporting the effect of exercise interventions on cutaneous microvascular reactivity in the foot in people with diabetes. A period of 12 weeks of moderate-intensity or low-volume high-intensity exercise may not be enough to elicit functional improvements in foot microvascular reactivity in adults with type 2 diabetes and obesity. Larger, sufficiently powered, prospective studies are necessary to determine if additional weight loss and/or higher exercise volume is required.

Immunomodulatory Bandage for Accelerated Healing of Diabetic Wounds

Diabetic foot ulcers are challenging to treat. Current strategies to treat these wounds focus on preventing infection and promoting tissue regrowth but are ineffective in many individuals. Low-grade chronic inflammation is present in individuals with diabetes, and altering the inflammatory responses at the wound site could be an alternate approach to promote healing. We hypothesized that immunomodulation of the wound microenvironment would result in accelerated healing. To test this hypothesis, we began by characterizing the changes in the myeloid cell phenotype in a mouse model [leptin receptor knockout (KO) mouse] that closely mimics the type 2 diabetes condition observed in humans. We observed increased numbers of monocytes and neutrophils in the circulation of the KO mice compared to that in wild-type control mice. We also observed several phenotypic changes in neutrophils from the KO diabetic mice, suggesting low-grade systemic inflammation. Hence, we developed a rapamycin-loaded chitosan scaffold that may be used to modulate immune responses. The use of these immunomodulatory scaffolds at a wound site resulted in accelerated healing compared to the healing using blank scaffolds. In summary, our data suggest that immunomodulation may be a viable strategy to promote the healing of wounds in individuals with diabetes.

Effect of intermittent pneumatic compression with different inflation pressures on the distal microvascular responses of the foot in people with type 2 diabetes mellitus

Intermittent pneumatic compression (IPC) is commonly used to improve peripheral circulation of the lower extremity. However, its therapeutic dosage for people with type 2 diabetes mellitus (DM) at risk for ulcers is not well established. This study explored the effect of IPC with different inflation pressures on the distal microvascular responses of the foot in people with type 2 DM. Twenty-four subjects with and without DM were recruited. Three IPC protocols with inflation pressures of 60, 90, and 120 mmHg were applied to the foot. The foot skin blood flow (SBF) responses were measured by laser Doppler flowmetry during and after IPC interventions. Results show that all three IPC interventions significantly increased foot SBF of IPC stage in healthy subjects, but only 90 and 120 mmHg IPC significantly improved SBF in diabetic subjects. IPC with 90 and 120 mmHg showed a greater effect than 60 mmHg in both groups, but 120 mmHg IPC was more effective for diabetic subjects. This study demonstrates that 90 and 120 mmHg are effective dosages of IPC for improving blood flow in healthy people, and 120 mmHg IPC may be more suitable for people with type 2 DM.

Huangbai liniment and berberine promoted wound healing in high-fat diet/Streptozotocin-induced diabetic rats

Diabetic ulcer is a challenging complication of diabetes mellitus but current treatments cannot achieve satisfactory results. In this study, the effect of Huangbai liniment (HB) and berberine on the wound healing in high fat diet/streptozotocin injection induced diabetic rats was investigated by RNA-seq technology. HB topical treatment promoted wound healing in the diabetic patients and diabetic rats, and it affected multiple processes, of which IL-17 signalling pathway was of importance. Inhibiting IL-17a by its inhibitor or antibody remarkably facilitated wound healing and HB significantly repressed the high IL-17 expression and its downstream targets, including Cxcl1, Ccl2, Mmp3, Mmp9, G-CSF, IL1B and IL6, in diabetic wounds, promoted T-AOC, SOD activity and GSH levels; decreased the levels of nitrotyrosine and 8-OHdG; enhanced angiogenesis-related CD31, PDGF-BB and ANG1 expression; inhibited cleaved caspase-3 levels and promoted TIMP1 and TGFB1. Moreover, berberine (a major component in HB) repressed the IL-17 signalling pathway, and promoted wound healing in diabetes mellitus. This study highlights the strategy of targeting IL-17a in diabetic wounds, deepens the understanding of wound healing in diabetes mellitus in a dynamic way and reveals the characteristics of HB and berberine in promoting wound healing of type 2 diabetes mellitus.

45S5 Bioglass® works synergistically with siRNA to downregulate the expression of matrix metalloproteinase-9 in diabetic wounds

Diabetic chronic wounds are difficult to heal because of the presence of excessive inflammation and high overexpression of matrix metalloproteinase-9 (MMP-9), which greatly affects the quality of life of patients with diabetes and increases the risk of death. Thus, the regulation of excessive inflammation and inhibition of MMP-9 overexpression are effective strategies to improve diabetic wound healing. The present study is the first to demonstrate that ion products of 45S5 Bioglass® (BG) can work with small interfering RNA of MMP9 (MMP9-siRNA) to reduce MMP-9 expression in tissue-forming cells and enhance the synthesis of extracellular matrix proteins (ECMs). Specifically, the BG ionic products can stimulate macrophages to convert to M2 phenotype, thereby creating a proregenerative inflammation microenvironment to indirectly suppress the expression of MMP-9 in tissue-forming cells. Chitosan nanoparticles encapsulating MMP9-siRNA (MMP9-siNP) can directly lower MMP-9 expression in tissue-forming cells. In addition, BG ionic products can promote the vascularization of endothelial cells and ECM protein synthesis by fibroblasts. Thus, injectable BG/sodium alginate (BG/SA) hydrogels loaded with MMP9-siNP can significantly accelerate the healing process of full-thickness excision wounds of diabetic rats by decreasing MMP-9 expression, improving collagen synthesis, and enhancing angiogenesis in the wounds, thereby demonstrating their great application potential in treating diabetic chronic wounds. STATEMENT OF SIGNIFICANCE: Excessive inflammation and high overexpression of MMP-9 have been considered as factors that severely hinder the healing process of diabetic chronic wounds. Effective strategies are required for the regulation of excessive inflammation and inhibition of MMP-9 overexpression to enhance diabetic wound healing. In the present work, an injectable bioglass/sodium alginate (BG/SA) hydrogel loaded with MMP9-siNP was developed; this hydrogel significantly accelerated the healing process of full-thickness excision wounds of diabetic rats by decreasing MMP-9 expression, improving collagen accumulation, and enhancing angiogenesis in the wounds. Thus, the BG/SA hydrogel loaded with MMP9-siNP has great potential for use in healing of diabetic chronic wounds.

State of the field: cellular and exosomal therapeutic approaches in vascular regeneration

Pathologies of the vasculature including the microvasculature are often complex in nature, leading to loss of physiological homeostatic regulation of patency and adequate perfusion to match tissue metabolic demands. Microvascular dysfunction is a key underlying element in the majority of pathologies of failing organs and tissues. Contributing pathological factors to this dysfunction include oxidative stress, mitochondrial dysfunction, endoplasmic reticular (ER) stress, endothelial dysfunction, loss of angiogenic potential and vascular density, and greater senescence and apoptosis. In many clinical settings, current pharmacologic strategies use a single or narrow targeted approach to address symptoms of pathology rather than a comprehensive and multifaceted approach to address their root cause. To address this, efforts have been heavily focused on cellular therapies and cell-free therapies (e.g., exosomes) that can tackle the multifaceted etiology of vascular and microvascular dysfunction. In this review, we discuss 1) the state of the field in terms of common therapeutic cell population isolation techniques, their unique characteristics, and their advantages and disadvantages, 2) common molecular mechanisms of cell therapies to restore vascularization and/or vascular function, 3) arguments for and against allogeneic versus autologous applications of cell therapies, 4) emerging strategies to optimize and enhance cell therapies through priming and preconditioning, and, finally, 5) emerging strategies to bolster therapeutic effect. Relevant and recent clinical and animal studies using cellular therapies to restore vascular function or pathologic tissue health by way of improved vascularization are highlighted throughout these sections.

Cutaneous microvascular reactivity in Charcot neuroarthropathy: a systematic review and meta-analysis

Background

To systematically evaluate the literature investigating the relationship between cutaneous microvascular reactivity in the foot of adults with diabetes-related Charcot neuroarthropathy compared to a non-Charcot adult control group.

Methods

A systematic search was conducted to June 2021 using the biomedical databases EBSCO Megafile Ultimate, Cochrane Library and EMBASE. Original research conducting comparative investigation of cutaneous microvascular reactivity in the foot of adults with diabetes and any pattern of acute or chronic Charcot neuroarthropathy and any non-Charcot adult control groups were included. A modified Critical Appraisal Skills Programme tool was used for quality appraisal. Cutaneous microvascular reactivity in diabetes-related Charcot neuroarthropathy data were synthesised and meta-analysis conducted where possible.

Results

The search strategy identified 1,684 articles, with seven eligible for inclusion. Included studies used various methodologies and equipment to assess cutaneous microvascular reactivity in 553 participants (162 with Charcot neuroarthropathy). Cutaneous microvascular reactivity in Charcot neuroarthropathy groups was impaired compared to uncomplicated diabetes groups. Meta-analysis investigating the difference in response to thermal hyperaemia demonstrated a significant difference in cutaneous microvascular reactivity between Charcot neuroarthropathy and peripheral neuropathy with a large, pooled effect size (SMD 1.46 95% CI: 0.89–2.02) and low heterogeneity (I² = 4%, T² = 0.01) indicating that the cutaneous microvascular response is more impaired in peripheral neuropathy than in Charcot neuroarthropathy.

Conclusions

Charcot neuroarthropathy is associated with greater cutaneous microvascular reactivity in the periphery relative to diabetes cohorts with diabetes-related peripheral neuropathy alone. It is unknown if this occurs prior to, or as a result of, Charcot neuroarthropathy.

Risk of Foot Ulcer and Lower-Extremity Amputation Among Participants in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study

OBJECTIVE

Intensive glycemic control reduces the risk of kidney, retinal, and neurologic complications in type 1 diabetes (T1D), but whether it reduces the risk of lower-extremity complications is unknown. We examined whether former intensive versus conventional glycemic control among Diabetes Control and Complications Trial (DCCT) participants with T1D reduced the long-term risk of diabetic foot ulcers (DFUs) and lower-extremity amputations (LEAs) in the subsequent Epidemiology of Diabetes Interventions and Complications (EDIC) study.

RESEARCH DESIGN AND METHODS

DCCT participants (n = 1,441) completed 6.5 years on average of intensive versus conventional diabetes treatment, after which 1,408 were enrolled in EDIC and followed annually over 23 years for DFU and LEA occurrences by physical examination. Multivariable Cox proportional hazard regression models estimated associations of DCCT treatment assignment and time-updated exposures with DFU or LEA.

RESULTS

Intensive versus conventional glycemic control was associated with a significant risk reduction for all DFUs (hazard ratio 0.77 [95% CI 0.60, 0.97]) and a similar magnitude but nonsignificant risk reduction for first-recorded DFUs (0.78 [0.59, 1.03]) and first LEAs (0.70 [0.36, 1.36]). In adjusted Cox models, clinical neuropathy, lower sural nerve conduction velocity, and cardiovascular autonomic neuropathy were associated with higher DFU risk; estimated glomerular filtration rate <60 mL/min/1.73 m2, albuminuria, and macular edema with higher LEA risk; and any retinopathy and greater time-weighted mean DCCT/EDIC HbA1c with higher risk of both outcomes (P < 0.05).

CONCLUSIONS

Early intensive glycemic control decreases long-term DFU risk, the most important antecedent in the causal pathway to LEA.

Sprayable methacrylic anhydride-modified gelatin hydrogel combined with bionic neutrophils nanoparticles for scar-free wound healing of diabetes mellitus

Hard-to-healing or nonhealing diabetic wounds caused by hyperglycemia, bacterial infection and chronic inflammation are becoming a challenge globally. In this study, a novel hydrogel for diabetic wound healing composed of methacrylic anhydride-modified gelatin (GelMA) hydrogel and mimicking neutrophil nanoparticles was originally created. The prepared GelMA hydrogel has good sprayability and film-formation ability under blue light illumination (wavelength = 435-480 nm). Nanoparticles mimicking neutrophils belong to a double enzyme system that are encapsulated in ZIF-8 nanoparticles, which can consume glucose to produce HClO, ensuring a decrease in the glucose concentration of the wound and growth inhibition in bacteria. The hydrogel also has excellent biocompatibility, which can promote the growth and proliferation of fibroblasts. More importantly, the hydrogel can accelerate wound healing in type I diabetic rats owing to the downregulation of proinflammatory cytokines, and the wound with an area of 1 cm² can be almost fully healed with no formation of the scar on the 21st day, as verified by histochemistry and immunohistochemistry. All these combinations indicate its potential in diabetic wound treatment.

Dynamic contrast enhanced - MRI efficiency in detecting embolization-induced perfusion defects in a rabbit model of critical-limb-ischemia

Critical limb ischemia (CLI) is a severe disease which affects about 2 million people in the US. Its prevalence is assessed at 800/100,000 population. However, no reliable tools are currently available to assess perfusion defects at the muscle tissue level. DCE-MRI is a technique that holds the potential to be effective in achieving this goal. However, preclinical studies performed with DCE-MRI have indicated low sensitivity assessing perfusion at resting state. To improve these previous results, in this work we propose new methodologies for data acquisition and analysis and we also revisit the biological model used for evaluation. Eleven rabbits underwent embolization of a lower limb. They were imaged at day 7 after embolization using DCE-MRI, performed on a 4.7 T small imaging device. Among them, n = 4 rabbits were used for MRI sequence optimization and n = 6 for data analysis after one exclusion. Normalized Areas under the curve (AUCn), and kinetic parameters such as K_trans and V_d resulting from the Tofts-Kety modeling (KTM) were calculated on the embolized and contralateral limbs. Average and heterogeneity features, consisting on standard-deviation and quantiles, were calculated on muscle groups and whole limbs. The Wilcoxon and Fisher-tests were performed to compare embolized and contralateral regions of interests. The Wilcoxon test was also used to compare features of parametric maps. Quantiles of 5 and 95% in the contralateral side were used to define low and high outliers. A P-value <0.05 was considered statistically significant. Average features were inefficient to identify injured muscles, in agreement with the low sensitivity of the technique previously reported by the literature. However, these findings were dramatically improved by the use of additional heterogeneity features (97% of total accuracy for group muscles, P < 0.01 and 100% of total accuracy for the total limbs). The mapping analysis and automatic outlier detection quantification improvement was explained by the presence of local hyperemia that impair the average calculations. The analysis with KTM did not provide any additional information compared to AUCn. The DCE technique can be effective in detecting embolization-induced disorders of limb muscles in a CLI model when heterogeneity is taken into account in the data processing, even without vascular stimulation. The simultaneous presence of areas of ischemia and hyperemia appeared as a signature of the injured limbs. These areas seem to reflect the simultaneous presence of infarcted areas and viable peripheral areas, characterized by a vascular response that is visible in DCE.

Effect of Exercise Volume on Plantar Microcirculation and Tissue Hardness in People With Type 2 Diabetes

Objective: Exercise has been reported to be beneficial for people with type 2 diabetes (T2DM), but exercise, especially weight-bearing exercise, may increase the risk of diabetic foot ulcers (DFUs). This study aimed to explore the associations between different volumes of weight-bearing physical activities and plantar microcirculation and tissue hardness in people with T2DM.

Methods: 130 elderly people with T2DM were enrolled for this cross-sectional study. They were classified into the high exercise volume group and the low exercise volume group based on their weekly energy expenditure (metabolic equivalents per week) in the past year. Weekly energy expenditure was calculated using the International Physical Activity Questionnaire and the Compendium of Physical Activities. The plantar oxygen saturation (SO₂) and soft tissue hardness of each participant’s right foot were measured.

Results: A total of 80 participants completed the trial. The average exercise energy expenditure of the high exercise volume group and the low exercise volume group were significantly different (p < 0.05). The results showed that the SO₂ of the high exercise volume group (67.25 ± 6.12%) was significantly higher than the low exercise volume group (63.75 ± 8.02%, p < 0.05). The plantar tissue hardness of the high exercise volume group was lower than the low exercise volume group in the big toe, midfoot and hindfoot regions (p < 0.05).

Conclusion: This study demonstrates that higher volumes of exercise are associated with better plantar microcirculation and lower plantar tissue hardness in people with T2DM. The findings of this study indicate that weight-bearing exercise may not increase risk of developing diabetic foot ulcers.

Effect of Vibration on Alleviating Foot Pressure-Induced Ischemia under Occlusive Compression

Objectives

Foot ulcers often occur in people with diabetes because of pressure-induced tissue ischemia. Vibration has been reported to be helpful in alleviating mechanical damage and promoting wound healing. The objective of this study is to explore whether vibration can relieve reactive hyperemia in foot tissue under occlusive compression.

Methods

Thirteen healthy adults participated in the study. Each foot was placed under occlusive compression without or with vibration intervention, which was randomly assigned every other day. The dorsal foot skin blood flow (SBF) was measured pre- and postintervention for each subject in each test. Temporal variations and spectral features of SBF were recorded for comparison.

Results

The results showed that subjects displayed an obvious reactive hyperemia in the foot tissue after pressure occlusion, whereas they displayed a more regular SBF when vibration was applied along with occlusive compression. Moreover, the amplitude of metabolic, neurogenic, and myogenic pathways for SBF was significantly reduced during the hyperemia process when vibration was applied.

Conclusions

This study demonstrated that vibration can effectively reduce the level of hyperemia in foot tissue under occlusive compression and also induce less protective physiological regulatory activities. This is helpful for protecting foot tissue from pressure-induced ischemic injury and foot ulcers.

Principal predictors of major adverse limb events in diabetic peripheral artery disease: A narrative review

Background and aims

The increasing prevalence of diabetes mellitus is causing a massive growth of peripheral artery disease incidences, a disabling complication of diabetic atherosclerosis, which leads often to the amputation of the affected limb. Critical limb ischemia is the terminal disease stage, which requires a prompt intervention to relieve pain and save limbs. However, patients undergoing revascularization often suffer from cardiovascular, cerebrovascular and major adverse limb events with poor outcomes. Furthermore, the same procedure performed in apparently similar patients has various outcomes and lack of an outcome predictive support causes a high lower limb arterial revascularization rate with disastrous effects for patients. We collected the main risk factors of major adverse limb events in a more readable and immediate format of the topic, to propose an overview of parameters to manage effectively peripheral artery disease patients and to propose basics of a new predictive tool to prevent from disabling vascular complications of the disease.

Methods

Most recent and updated literature about the prevalence of major adverse limb events in peripheral artery disease was reviewed to identify possible main predictors.

Results

In this article, we summarized major risk factors of limb revascularization failure and disabling vascular complications collecting those parameters principally responsible for major adverse limb events, which provides physio-pathological explanation of their role in peripheral artery disease.

Conclusion

We evaluated and listed a panel of possible predictors of MALE (Major Adverse Limb Event) in order to contribute to the development of a predictive score, based on a summary of the main risk factors reported in scientific articles, which could improve the management of peripheral artery disease by preventing vascular accidents.

The effect of rheopheresis treatment on the cytokine profile in diabetic foot syndrome with hyperviscosity in the aspect of clinical changes: A preliminary study

BACKGROUND

Rheopheresis is a selective extracorporal double cascade filtration treatment, which can extract high molecular weight proteins being responsible for hyperviscosity. As the whole blood and plasma viscosity decrease microcirculation improves.

OBJECTIVE

In this preliminary study we aimed to analyze additional beneficial effects of rheopheresis treatment with changes of pro-inflammantory cytokine levels in diabetic foot syndrome patients.

METHODS

Two rheopheresis treatments were performed for 6 patients with diabetic foot ulcer and/or neuropathy on consecutive days. Before and after the treatments whole blood and plasma viscosity, as well as IL-6, IL-8, and TNF-alpha serum levels were determined, and complex angiological and ENG examinations were performed.

RESULTS

Rheopheresis decreased the whole blood and plasma viscosity, and the serum levels of IL-6, IL-8, and TNF-alpha were markedly reduced. The life quality of the patients improved, the ulcers healed, the pain decreased. Daily dose of analgesics decreased in the follow-up period (6 months). The ENG showed improving amplitude and/or normalizing conduction speed.

CONCLUSION

Application of rheopheresis in patients with diabetic foot syndrome has a beneficial effect, providing favorable rheological condition, normalizing cytokine profile and reducing the sensorineural symptoms.

Angiogenic Effects and Crosstalk of Adipose-Derived Mesenchymal Stem/Stromal Cells and Their Extracellular Vesicles with Endothelial Cells

Adipose-derived mesenchymal stem/stromal cells (ASCs) are an adult stem cell population able to self-renew and differentiate into numerous cell lineages. ASCs provide a promising future for therapeutic angiogenesis due to their ability to promote blood vessel formation. Specifically, their ability to differentiate into endothelial cells (ECs) and pericyte-like cells and to secrete angiogenesis-promoting growth factors and extracellular vesicles (EVs) makes them an ideal option in cell therapy and in regenerative medicine in conditions including tissue ischemia. In recent angiogenesis research, ASCs have often been co-cultured with an endothelial cell (EC) type in order to form mature vessel-like networks in specific culture conditions. In this review, we introduce co-culture systems and co-transplantation studies between ASCs and ECs. In co-cultures, the cells communicate via direct cell-cell contact or via paracrine signaling. Most often, ASCs are found in the perivascular niche lining the vessels, where they stabilize the vascular structures and express common pericyte surface proteins. In co-cultures, ASCs modulate endothelial cells and induce angiogenesis by promoting tube formation, partly via secretion of EVs. In vivo co-transplantation of ASCs and ECs showed improved formation of functional vessels over a single cell type transplantation. Adipose tissue as a cell source for both mesenchymal stem cells and ECs for co-transplantation serves as a prominent option for therapeutic angiogenesis and blood perfusion in vivo.

The Role of Cutaneous Microcirculatory Responses in Tissue Injury, Inflammation and Repair at the Foot in Diabetes

Diabetic foot syndrome is one of the most costly complications of diabetes. Damage to the soft tissue structure is one of the primary causes of diabetic foot ulcers and most of the current literature focuses on factors such as neuropathy and excessive load. Although the role of blood supply has been reported in the context of macro-circulation, soft tissue damage and its healing in the context of skin microcirculation have not been adequately investigated. Previous research suggested that certain microcirculatory responses protect the skin and their impairment may contribute to increased risk for occlusive and ischemic injuries to the foot. The purpose of this narrative review was to explore and establish the possible link between impairment in skin perfusion and the chain of events that leads to ulceration, considering the interaction with other more established ulceration factors. This review highlights some of the key skin microcirculatory functions in response to various stimuli. The microcirculatory responses observed in the form of altered skin blood flow are divided into three categories based on the type of stimuli including occlusion, pressure and temperature. Studies on the three categories were reviewed including: the microcirculatory response to occlusive ischemia or Post-Occlusive Reactive Hyperaemia (PORH); the microcirculatory response to locally applied pressure such as Pressure-Induced Vasodilation (PIV); and the interplay between microcirculation and skin temperature and the microcirculatory responses to thermal stimuli such as reduced/increased blood flow due to cooling/heating. This review highlights how microcirculatory responses protect the skin and the plantar soft tissues and their plausible dysfunction in people with diabetes. Whilst discussing the link between impairment in skin perfusion as a result of altered microcirculatory response, the review describes the chain of events that leads to ulceration. A thorough understanding of the microcirculatory function and its impaired reactive mechanisms is provided, which allows an understanding of the interaction between functional disturbances of microcirculation and other more established factors for foot ulceration.

Pharmacokinetics, Safety, and Tolerability of the α2C -Adrenoreceptor Antagonist BAY 1193397 in Healthy Male Subjects

The α_2C -adrenoreceptor antagonist BAY 1193397 is in development for the oral treatment of diabetic foot ulcers. Safety, tolerability, and pharmacokinetics of BAY 1193397 were investigated in 3 randomized, single-center phase 1 studies in healthy male subjects: a first-in-human study (single oral doses of 0.5-50 mg), a relative bioavailability and food effect study (single doses of 1 and 10 mg), and a multiple-dose escalation study (using 2 and 5 mg twice daily and 10 and 20 mg once daily for 9 consecutive days). BAY 1193397 was rapidly absorbed in the fasted state, peak concentrations were reached between 0.6 and 2 hours. The mean terminal half-life was in the range of 17 to 20 hours. Area under the plasma concentration-time curve and maximum concentration appeared to be dose proportional, with a negligible food effect. There were no high-accumulation effects of BAY 1193397 after repeated dosing. BAY 1193397 was safe and well tolerated. At supratherapeutic plasma concentrations, there were slight transient increases in norepinephrine levels, heart rate, and blood pressure that were more pronounced after a single dose compared to steady state and appeared to be maximum concentration dependent. The results of the presented studies support the conduct of subsequent clinical trials with BAY 1193397 in patients with diabetes and compromised microcirculation.