Wound Healing in Diabetes: Hemorheological and Microcirculatory Aspects

Current and promising applications of MOF composites in the healing of diabetes wounds

Diabetes mellitus is an exponentially growing chronic metabolic disease identified by prolonged hyperglycemia that leads to a plethora of health problems. It is well established that the skin of diabetic patients is more prone to injury, and hence, wound healing is an utmost critical restorative process for injured skin and other tissues. Diabetes patients have problems with wound healing at all stages, which ultimately results in delays in the healing process. Therefore, it is vital to find new medications or techniques to hasten the healing of wounds. Metal-organic frameworks (MOFs), an assorted class of porous hybrid materials comprising metal ions coordinated to organic ligands, can display great potential in accelerating diabetic wound healing due to their good physicochemical properties. The release of metal ions during the degradation of MOFs can promote the differentiation of fibroblasts into myofibroblasts and subsequently angiogenesis. Secondly, similar to enzyme-like active substances, they can eliminate reactive oxygen species (ROS) overproduction (secondary to the bio-load of wound bacteria), which is conducive to accelerating diabetic wound healing. Subsequently, MOFs can support the slow release of drugs (molecular or gas therapeutics) in diabetic wounds and promote wound healing by regulating pathological signaling pathways in the wound microenvironment or inhibiting the expression of inflammatory factors. In addition, the combination of photodynamic and photothermal therapies using photo-stimulated porphyrin-based MOF nanosystems has brought up a new idea for treating complicated diabetic wound microenvironments. In this review, recent advances affecting diabetic wound healing, current means of rapid diabetic wound healing, and the limitations of traditional approaches are discussed. Further, the diabetic wound healing applications of MOFs have been discussed followed by the future challenges and directions of MOF materials in diabetic wound healing.

Electric Factors in Wound Healing

Significance: Electric factors such as electric charges, electrodynamic field, skin battery, and interstitial exclusion permeate wound healing physiology and physiopathology from injury to re-epithelialization. The understanding of how electric factors contribute to wound healing and how treatments may interfere with them is fundamental for the development of better strategies for the management of pathological scarring and chronic wounds. Recent Advances: Angiogenesis, cell migration, macrophage activation hemorheology, and microcirculation can interfere and be interfered with electric factors. New treatments with various types of electric currents, laser, light emitting diode, acupuncture, and weak electric fields applied directly on the wound have been developed to improve wound healing. Critical Issues: Despite the basic and clinical development, pathological scars such as keloids and chronic wounds are still a challenge. Future Directions: New treatments can be developed to improve skin wound healing taking into account the influence of electrical charges. Monitoring electrical activity during skin healing and the influence of treatments on hemorheology and microcirculation are examples of how to use knowledge of electrical factors to increase their effectiveness.

Updated Evaluation of Cholesterol's Influence on Membrane Oxygen Permeability

There is a surprising gap in knowledge regarding the mechanism of oxygen (O2) diffusional delivery at the level of tissues and cells. Yet, the effectiveness of tumor radiotherapy, the success of tissue engineering, and healthy metabolism all require ample intracellular oxygen. Tissue-level diffusion takes place in a complex and crowded macromolecular environment. Cholesterol-rich cellular membranes have been thought to reduce oxygen flux. Here, we use atomistic molecular dynamics simulations to update prior estimates of bilayer permeability and related parameters for 1-palmitoyl,2-oleoylphosphatidylcholine (POPC) and POPC/cholesterol bilayers, using a modified O2 model with improved membrane-water partitioning behavior. This work estimates an oxygen permeability coefficient of 15 ± 1 cm/s for POPC and 11.5 ± 0.4 cm/s for POPC/cholesterol (1:1 molecular ratio) at 37 °C. The permeability of POPC is found to be ~1/3 that of a water layer of similar thickness, and the permeability of POPC/cholesterol is estimated to be 20-30% below that of POPC. Void pathway visualization and free energy data support channeling of oxygen toward the center of cholesterol-incorporating membranes, while partition coefficient data suggest reduced membrane solubility of oxygen due to cholesterol. Further study is needed to understand whether diffusion pathway changes due to cholesterol and other molecular compositional factors influence oxygen availability within tissue.

How does oxygen diffuse from capillaries to tissue mitochondria? Barriers and pathways

Timely delivery of oxygen (O₂ ) to tissue mitochondria is so essential that elaborate circulatory systems have evolved to minimize diffusion distances within tissue. Yet, knowledge is surprisingly limited regarding the diffusion pathway between blood capillaries and tissue mitochondria. An established and growing body of work examines the influence cellular and extracellular structures may have on subcellular oxygen availability. This brief review discusses the physiological and pathophysiological significance of oxygen availability, highlights recent computer modelling studies of transport at the cell-membrane level, and considers alternative diffusion pathways within tissue. Experimental and computer modelling studies suggest that oxygen diffusion may be accelerated by cellular lipids, relative to cytosolic and interstitial fluids. Such acceleration, or 'channelling', would occur due to greatly enhanced oxygen solubility in lipids, especially near the midplane of lipid bilayers. Rapid long-range movement would be promoted by anisotropically enhanced lateral diffusion of oxygen along the midplane and by junctions holding lipid structures in close proximity to one another throughout the tissue. Clarifying the biophysical mechanism of oxygen transport within tissue will shed light on limitations and opportunities in tumour radiotherapy and tissue engineering.

Predictive Factors for Surgical Site Infections in Patients Undergoing Surgery for Breast Carcinoma

INTRODUCTION

Operative interventions for breast cancer are generally classified as clean surgeries. Surgical site infections (SSIs), while rare, do occur. This study sought to identify risk factors for SSI, using the National Surgical Quality Improvement Program (NSQIP).

METHODS

NSQIP's participant use data files (PUF) between 2012 and 2015 were examined. Female patients with invasive breast cancer who underwent surgery were identified through CPT and ICD9 codes. Non-SSI and SSI groups were compared and the statistical differences were addressed through propensity score weighting. Multivariate logistic regression testing was used to identify predictors of SSI.

RESULTS

This study examined 30 544 lumpectomies and 23 494 mastectomies. SSI rate was 1126/54 038 patients (2.1%). In the weighted dataset, mastectomy, diabetes, smoking, COPD, ASA class-severe, BMI >35 kg/m², and length of stay (LOS) >1 day were associated with an increased odds ratio (OR) of SSI. The OR for SSI was highest after mastectomy with reconstruction (OR 2.626, P < .001; 95% CI 2.073-3.325). Postoperative variables associated with an increased OR of SSIs included systemic infection, unplanned reoperation wound dehiscence, and renal failure.

CONCLUSION

Mastectomy, diabetes, smoking, COPD, ASA class-severe, BMI >35 kg/m², length of stay (LOS) >1 day are associated with an increased OR for SSIs following breast surgery.

Impact of Diabetes on 30-Day Complications in Mastectomy and Implant-Based Breast Reconstruction

BACKGROUND

Diabetic patients are known to be at increased risk of postoperative complications after multiple types of surgery. However, conflicting evidence exists regarding the association between diabetes and wound complications in mastectomy and breast reconstruction. This study evaluates the impact of diabetes on surgical outcomes after mastectomy procedures and implant-based breast reconstruction.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database review from 2010 to 2015 identified patients undergoing total, partial, or subcutaneous mastectomy, as well as immediate or delayed implant reconstruction. Primary outcomes included postoperative wound complications and implant failure. Preoperative variables and outcomes were compared between diabetic and nondiabetic patients. Multivariate regression was used to control for confounders.

RESULTS

The following groups were identified: partial (n = 52,583), total (n = 41,540), and subcutaneous mastectomy (n = 3145), as well as immediate (n = 4663) and delayed (n = 4279) implant reconstruction. Diabetes was associated with higher rates of superficial incisional surgical site infection (SSI) in partial mastectomy (odds ratio [OR] = 8.66; P = 0.03). Diabetes was also associated with higher rates of deep incisional SSI (OR = 1.61; P = 0.01) in subcutaneous mastectomy and both superficial (OR = 1.56; P = 0.04) and deep incisional SSI (OR = 2.07; P = 0.04) in total mastectomy. Diabetes was not associated with any wound complications in immediate reconstruction but was associated with higher rates of superficial incisional SSI (OR = 17.46; P < 0.001) in the delayed reconstruction group. There was no association with implant failure in either group.

CONCLUSIONS

Evaluation of the largest national cohort of mastectomy and implant reconstructive procedures suggests that diabetic patients are at significantly increased risk of 30-d postoperative infectious wound complications but present no difference in rates of early implant failure.

Experimental Study on Effects of Adipose-Derived Stem Cell-Seeded Silk Fibroin Chitosan Film on Wound Healing of a Diabetic Rat Model

BACKGROUND

Wound healing is a complex process that relies on growth factors and stimulation of angiogenesis. Tissue engineering materials composed of adipose-derived stem cells (ADSCs) and silk fibroin (SF)/chitosan (CS) may be able to solve this problem. The aim of this study was to investigate the wound-healing potential of ADSC-seeded SF/CS in streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

Thirty-six male Sprague-Dawley rats were purchased and randomly assigned into 3 groups: a control group (no graft), a group treated with SF/CS film graft, and a group treated with ADSC-seeded SF/CS graft. The number of animals in each group was 12. Diabetes was induced by an intraperitoneal injection of streptozotocin. A cutaneous wound was incised at the dorsal region of all the experimental animals. The ADSCs were labeled with CM-Dil fluorescent staining. Wound healing was assessed for all animal groups by observing the rate of wound closure and hematoxylin and eosin staining. The expression of epidermal growth factor, transforming growth factor-β, and vascular endothelial growth factor at the wound sites was studied by enzyme-linked immunosorbent assay to evaluate the effect of growth factors secreted by ADSCs. The differentiation of ADSCs was analyzed by immunofluorescence staining.

RESULTS

The ADSC-seeded SF/CS film treatment significantly increased the rates of wound closure in treated animals, and hence wound healing was drastically enhanced for ADSC-SF/CS treatment groups compared with control groups and SF/CS film treatment group. Histological observations showed the condition of wound healing. Enzyme-linked immunosorbent assay and immunofluorescence staining observations showed the secretion and differentiation of ADSCs, respectively.

CONCLUSIONS

Our analyses clearly suggested that it is feasible and effective to enhance wound healing in a diabetic rat model with ADSC-seeded SF/CS film.

The aneurysmal arteriovenous fistula - morphological study and assessment of clinical implications. A pilot study

Aneurysmal dilation of arteriovenous fistulae used for haemodialysis is a recognised complication but its clinical significance is a contentious issue. Our aims were to describe aneurysmal fistulae morphologically and clinically.Sixty patients underwent duplex scanning to measure the maximum diameter and skin thickness of their fistula. Haemodialysis function and bleeding risk were assessed clinically.The 75th percentile of maximum diameter was 2.05 cm. In addition to conventional diameter measurement, we describe a novel volume measurement technique which may be of value. No relationship was found between maximum diameter or volume and function, skin thickness or bleeding.Some studies define aneurysm at 2 cm (75th percentile); however, this definition and other arbitrary definitions lack clinical significance. This work suggests that fistula dilation should be considered together with clinical issues when determining the clinical significance of an aneurysm. Our finding that haemodialysis function, skin thickness and bleeding were not associated with diameter needs further study.

Off-label prescriptions in diabetic foot

Prescription of a drug outside of the indications for which it was originally approved by regulators is internationally known as "off-label" prescription. We describe off-label treatments for the diabetic foot reported in international scientific literature. This is a qualitative and descriptive bibliographical review based on the results of a search of the Medline international database. The criteria for review were publication between January 1985 and November 2013, and the MeSH (Medical Subject Heading) keywords "off-label use" OR "off-label" OR "off-label prescribing" plus "diabetic foot" were input on the search form. Nine studies were selected that contained information about off-label treatments for the diabetic foot. We conclude that the practice of off-label prescribing has potential benefits. In some situations an off-label prescription is the only treatment available for patients, either because a more targeted drug does not exist, or because other methods of treatment are ineffective or unavailable due to patient intolerance.

Identifying risk factors for surgical site infections in mastectomy patients using the National Surgical Quality Improvement Program database

BACKGROUND

The Centers for Disease Control and Prevention reported that surgical site infections (SSIs) create a significant hospital burden. To date, few multi-institutional studies have been performed to evaluate the risk factors for SSIs in mastectomy patients.

METHODS

By using the American College of Surgeons' National Surgical Quality Improvement Program database, all patients undergoing mastectomy from 2005 to 2009 were identified. The outcome was to determine the incidence rate and identify significant independent risk factors of SSIs.

RESULTS

The incidence of SSI was 2.3% (891 of 38,739; 95% confidence interval, 2.2%-2.5%) in patients undergoing mastectomy without reconstruction. Significant (P < .05) risk factors for SSI included a body mass index greater than 25, American Society of Anesthesiology classification of 3 or higher, diabetes mellitus, surgical time of 2 hours or longer (75th percentile), and current smoking status.

CONCLUSIONS

Before this study, there was wide variation in the incidence rate of surgical site infections in this patient population. This was a large-scale study to address these inconsistencies.

Antioxidative and aldose reductase-inhibitory effects of a fermentation filtrate of Rubus coreanus

Antioxidative and aldose reductase (AR)-inhibitory effects of a fermentation filtrate of Rubus coreanus (FRC) were investigated using corneal/retinal homogenate and lens cytosol, respectively. Rat corneal/retinal homogenate was treated with 50 µM FeCl₃ in the presence of FRC (3.2-100 µg/mL) for 30 min at 37℃, and thiobarbituric acid-reactive substances (TBARS) was quantified as a lipid peroxidation parameter. FRC markedly suppressed the TBARS production in a concentration-dependent manner, leading to 50% (IC₅₀) and 100% (IC₁₀₀) inhibitory concentrations of 20 and 95 µg/mL, respectively, which was similar to the effect of butylated hydroxyanisole. Activity of AR from rat lens was assayed in the presence of FRC (1-31.6 µg/mL) at 25℃ using glyceraldehyde as a substrate. FRC inhibited lens AR by 50% (IC₅₀) and 90% (IC₉₀) at approximately 2 and 31.6 µg/mL, respectively, comparable to the effect of quercetin. The results indicate that ERC could be a promising candidate for the improvement of eye injury and visual dysfunction of dry eye and diabetic patients.

The role of hyperbaric oxygen in the treatment of diabetic foot ulcers

Diabetic foot ulcers are still extremely difficult to heal. Therefore, therapeutic options to improve healing rates are continuously being explored. Hyperbaric oxygen (HBO) has been used in addition to standard treatment of the diabetic foot for more than 20 years. Evidence suggests that HBO reduces amputation rates and increases the likelihood of healing in infected diabetic foot ulcers, in association with improved tissue oxygenation, resulting in better quality of life. Nonetheless, HBO represents an expensive modality, which is only available in few centers. Moreover, adverse events necessitate a closer investigation of its safety. Finally, it is not entirely clear which patients stand to benefit from HBO and how these should be selected. In conclusion, HBO appears promising, but more experience is needed before its broad implementation in the routine care of the diabetic foot.