A human model of small fiber neuropathy to study wound healing

Meta-Analysis: Outcomes of Surgical and Medical Management of Diabetic Foot Osteomyelitis

BACKGROUND

The aim of this study was to evaluate clinical outcomes in the published literature on medical and surgical management of diabetic foot osteomyelitis (DFO).

METHODS

A PubMed and Google Scholar search of articles relating to DFO was performed over the dates of January 1931 to January 2020. Articles that involved Charcot arthropathy, case reports, small case series, review articles, commentaries, nonhuman studies, and non-English articles were excluded. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool was used to rate the bias of each study. A meta-analysis was performed using random-effects and inverse variance methods. The search yielded 1192 articles. After review and the removal of articles that did not meet inclusion criteria, 28 articles remained. Eighteen articles were related to the medical management of DFO and 13 articles were related to surgical management. Three articles looked at a combination of medical and surgical management and were included in both groups. Heterogeneity was evaluated using Cochran Q, I 2, τ2, and τ.

RESULTS

The average success rate was 68.2% (range, 17.0%-97.3%) for medical treatment and 85.7% (range, 65.0%-98.8%) for surgical and medical treatment. There were significant inconsistencies in accounting for peripheral arterial disease and peripheral neuropathy. There was significant heterogeneity in outcomes between studies. However, there was a high rate of successful treatment and a wide range between patients with medical treatment and combined surgical and medical treatment.

CONCLUSIONS

Additional properly designed prospective studies with gold-standard references for diagnosing osteomyelitis are needed to help determine whether medical management of DFO can be successful without surgical intervention.

Solvent-Free Polycaprolactone Dissolving Microneedles Generated via the Thermal Melting Method for the Sustained Release of Capsaicin

(1) Background: Dissolving microneedles (DMNs), a transdermal drug delivery system, have been developed to treat various diseases in a minimally invasive, painless manner. However, the currently available DMNs are based on burst release systems due to their hydrophilic backbone polymer. Although hydrophobic biodegradable polymers have been employed on DMNs for sustained release, dissolution in an organic solvent is required for fabrication of such DMNs. (2) Method: To overcome the aforementioned limitation, novel separable polycaprolactone (PCL) DMNs (SPCL-DMNs) were developed to implant a PCL-encapsulated drug into the skin. PCL is highly hydrophobic, degrades over a long time, and has a low melting point. Under thermal melting, PCL encapsulated capsaicin and could be fabricated into a DMN without the risk of toxicity from an organic solvent. (3) Results: Optimized SPCL-DMNs, containing PCL (height 498.3 ± 5.8 µm) encapsulating 86.66 ± 1.13 µg capsaicin with a 10% (w/v) polyvinyl alcohol and 20% (w/v) polyvinylpyrrolidone mixture as a base polymer, were generated. Assessment of the drug release profile revealed that this system could sustainably release capsaicin for 15 days from PCL being implanted in porcine skin. (4) Conclusion: The implantable SPCL-DMN developed here has the potential for future development of toxicity-free, sustained release DMNs.

A novel method to quantify cutaneous vascular innervation

INTRODUCTION

To develop a new method to quantify the density of nerves, vessels, and the neurovascular contacts, we studied skin biopsies in diabetes and control subjects.

METHODS

Skin biopsies with dual immunofluorescent staining were used to visualize nerves and blood vessels. The density of nerves, vessels, and their neurovascular contacts were quantified with unbiased stereology. Results were compared with examination findings, validated questionnaires, and autonomic function.

RESULTS

In tissue from 19 controls and 20 patients with diabetes, inter-rater and intra-rater intraclass correlation coefficients were high (>0.85; P < .001) for all quantitative methods. In diabetes, the nerve densities (P < .05), vessel densities (P < .01), and the neurovascular densities (P < .01) were lower compared with 20 controls. Results correlated with autonomic function, examination and symptom scores.

DISCUSSION

We report an unbiased, stereological method to quantify the cutaneous nerve, vessel and neurovascular density and offer new avenues of investigation into cutaneous neurovascular innervation in health and disease.

High-fat diet exacerbates postoperative pain and inflammation in a sex-dependent manner

Obesity is often associated with increased pain, but little is known about the effects of obesity and diet on postoperative pain. In this study, effects of diet and obesity were examined in the paw incision model, a preclinical model of postoperative pain. Long-Evans rats were fed high-fat diet (40% calories from butter fat) or low-fat normal chow. Male rats fed high-fat diet starting 6 weeks before incision (a diet previously shown to induce markers of obesity) had prolonged mechanical hypersensitivity and an overall increase in spontaneous pain in response to paw incision, compared with normal chow controls. Diet effects in females were minor. Removing high-fat diet for 2 weeks before incision reversed the diet effects on pain behaviors, although this was not enough time to reverse high-fat diet-induced weight gain. A shorter (1 week) exposure to high-fat diet before incision also increased pain behaviors in males, albeit to a lesser degree. The 6-week high-fat diet increased macrophage density as examined immunohistochemically in lumbar dorsal root ganglion even before paw incision, especially in males, and sensitized responses of peritoneal macrophages to lipopolysaccharide stimuli in vitro. The nerve regeneration marker growth-associated protein 43 (GAP43) in skin near the incision (day 4) was higher in the high-fat diet group, and wound healing was delayed. In summary, high-fat diet increased postoperative pain particularly in males, but some diet effects did not depend on weight gain. Even short-term dietary manipulations, that do not affect obesity, may enhance postoperative pain.

Diabetes care in figures: current pitfalls and future scenario

Diabetes mellitus (DM) epidemic-on a global scale-is a major and snowballing threat to public health, healthcare systems and economy, due to the cascade of pathologies triggered in a long-term manner after the DM manifestation. There are remarkable differences in the geographic disease spread and acceleration of an increasing DM prevalence recorded. Specifically, the highest initial prevalence of DM was recorded in the Eastern-Mediterranean region in 1980 followed by the highest acceleration of the epidemic characterised by 0.23% of an annual increase resulted in 2.3 times higher prevalence in the year 2014. In contrast, while the European region in 1980 demonstrated the second highest prevalence, the DM epidemic developments were kept much better under control compared to all other regions in the world. Although both non-modifiable and modifiable risk factors play a role in DM predisposition, cross-sectional investigations recently conducted amongst elderly individuals demonstrate that ageing as a non-modifiable risk factor is directly linked to unhealthy lifestyle as a well-acknowledged modifiable risk factor which, in turn, may strongly promote ageing process related to DM even in young populations. Consequently, specifically modifiable risk factors should receive a particular attention in the context of currently observed DM epidemic prognosed to expand significantly over 600 million of diabetes-diseased people by the year 2045. The article analyses demographic profiles of DM patient cohorts as well as the economic component of the DM-related crisis and provides prognosis for future scenarios on a global scale. The innovative approach by predictive diagnostics, targeted prevention and treatments tailored to the person in a suboptimal health condition (before clinical onset of the disease), as the medicine of the future is the most prominent option to reverse currently persisting disastrous trends in diabetes care. The key role of biomedical sciences in the future developments of diabetes care is discussed.

Comparison of Neurovascular Characteristics of Facial Skin in Patients After Primary and Revision Rhytidectomies

Importance

Wound healing influences both the cosmetic and functional outcomes of facial surgery. Study of cutaneous innervation may afford insight into patients' preoperative wound healing potential and aid in their selection of appropriate surgical procedures.

Objective

To present the quantitative and qualitative differences of epidermal nerve fibers (ENFs), neurotransmitters, vasculature, and mast cells in facial skin among patients after primary and revision rhytidectomies.

Design, Setting, and Participants

This pilot study collected cutaneous specimens from 8 female patients aged 42 to 66 years who underwent primary rhytidectomy (n = 5) and revision rhytidectomy (n = 3) at Centennial Lakes Surgery Center, Edina, Minnesota, from July 2010 to March 2014. Tissue was processed for confocal/epifluorescence microscopy and indirect immunofluorescent localization of several neural and tissue antigens as well as basement membrane and mast cell markers.

Intervention

Primary rhytidectomy vs revision rhytidectomy with selection of a small area of redundant, otherwise disposed of tissue anterior to the tragus for ENF study.

Main Outcomes and Measures

Demographic characteristics included smoking status; 10-point rating scales for facial sensation, pain, and paresthesias; and confocal/epifluorescence microscopy to quantify ENFs, neurotransmitters, vasculature, and mast cells.

Results

Patients in the primary rhytidectomy group had a mean (SD) of 54.4 (31.6) ENFs/mm (range, 14.2-99.2 ENFs/mm), and those in the revision rhytidectomy group had a mean (SD) of 18.6 (5.8) ENFs/mm (range, 13.8-25.0 ENFs/mm). A patient in the primary rhytidectomy group was a 25-pack-year smoker and had 14.2 ENFs/mm, the lowest in both groups. In addition to these structural neural changes, functional neural changes in revision rhytidectomy samples included qualitative changes in normal neural antigen prevalence (substance P, calcitonin gene-related peptide, and vasoactive intestinal peptide). Capillary loops appeared less robust and were less common in dermal papilla among samples from both the primary and revision groups, and mast cells were more degranulated. No differences were found in subjective, self-reported postoperative facial sensation.

Conclusions and Relevance

Previous skin elevation was associated with decreased epidermal nerve fiber density and qualitative changes in dermal nerves, capillaries, and mast cells in a clinical sample of patients undergoing rhytidectomy. Future research is needed to determine whether histological findings predict wound healing and to better understand the effects of surgery on regenerative capacity of epidermal nerve fibers.

Level of Evidence

NA.

Diabetic Foot Ulcers and Epidermal Growth Factor: Revisiting the Local Delivery Route for a Successful Outcome

Soon after epidermal growth factor (EGF) discovery, some in vivo models appeared demonstrating its property to enhance cutaneous wound healing. EGF was the first growth factor (GF) introduced in the clinical arena as a healing enhancer, exerting its mitogenic effects on epithelial, fibroblastoid, and endothelial cells via a tyrosine kinase membrane receptor. Compelling evidences from the 90s documented that, for EGF, locally prolonged bioavailability and hourly interaction with the receptor were necessary for a successful tissue response. Eventually, the enthusiasm on the clinical use of EGF to steer the healing process was wiped out as the topical route to deliver proteins started to be questioned. The simultaneous in vivo experiments, emphasizing the impact of the parenterally administered EGF on epithelial and nonepithelial organs in terms of mitogenesis and cytoprotection, rendered the theoretical fundamentals for the injectable use of EGF and shaped the hypothesis that locally infiltrating the diabetic ulcers would lead to an effective healing. Although the diabetic chronic wounds microenvironment is hostile for local GFs bioavailability, EGF local infiltration circumvented the limitations of its topical application, thus expanding its therapeutic prospect. Our clinical pharmacovigilance and basic studies attest the significance of the GF local infiltration for chronic wounds healing.

Impaired wound healing: facts and hypotheses for multi-professional considerations in predictive, preventive and personalised medicine

Whereas the physiologic wound healing (WH) successfully proceeds through the clearly defined sequence of the individual phases of wound healing, chronic non-healing wounds/ulcers fail to complete the individual stages and the entire healing process. There are many risk factors both modifiable (such as stress, smoking, inappropriate alcohol consumption, malnutrition, obesity, diabetes, cardio-vascular disease, etc.) and non-modifiable (such as genetic diseases and ageing) strongly contributing to the impaired WH. Current statistics demonstrate that both categories are increasingly presented in the populations, which causes dramatic socio-economic burden to the healthcare sector and society at large. Consequently, innovative concepts by predictive, preventive and personalised medicine are crucial to be implemented in the area. Individual risk factors, causality, functional interrelationships, molecular signature, predictive diagnosis, and primary and secondary prevention are thoroughly analysed followed by the expert recommendations in this paper.

Skin-derived precursor cells promote wound healing in diabetic mice

BACKGROUND

Impaired wound healing as one of the complications arising from diabetes mellitus is a serious clinical issue. Recently, various cell therapies have been reported for promotion of wound healing. Skin-derived precursor cells (SKPs) are multipotent adult stem cells with the tendency to differentiate into neurons. We investigated the potency of promoting diabetic wound healing by the application of SKPs.

METHODS

Skin-derived precursor cells isolated from diabetic murine skin were cultured in sphere formation medium. At passage 2, they were suspended in phosphate-buffered saline (PBS), and applied topically to full-thickness excisional cutaneous wounds in diabetic mice. Application of PBS served as controls (n = 21 for each group; n = 42 total). Time to closure and percentage closure were calculated by morphometry. Wounds were harvested at 10 and 28 days and then processed, sectioned, and stained (CD31, α-smooth muscle actin, and neurofilament heavy chain) to quantify vascularity and neurofilaments.

RESULTS

Wounds treated with SKPs demonstrated a significantly decreased time to closure (18.63 days) compared with PBS-control wounds (21.72 days, P < 0.01), and a significant improvement in percentage closure at 7, 10, 14, and 18 days compared with PBS-control wounds (P < 0.01). Histological analysis showed that the Capillary Score (the number of vessels/mm2) was significantly higher in SKP-treated wounds at day 10 but not at day 28. Nerve Density (the number of neurofilaments/mm2) had increased significantly in SKP-treated wounds at day 28 compared with control group. Some applied SKPs were stained by neurofilament heavy chain, which demonstrates that SKPs directly differentiated into neurons.

CONCLUSIONS

Skin-derived precursor cells promoted diabetic wound healings through vasculogenesis at the early stage of wound healing. Skin-derived precursor cells are a possible therapeutic tool for diabetic impaired wound healing.