Local insulin-zinc injection accelerates skin donor site wound healing

Topical delivery of insulin using novel organogel formulations: An approach for the management of diabetic wounds

Diabetes mellitus is a growing chronic form of diabetes, with lengthy health implications. It is predicted as poor diabetic wound recovery affects roughly 25% of all diabetes mellitus patients, frequently resulting in lower traumatic injury and severe external factors and emotional expenses. The insulin-resistant condition increases biofilm development, making diabetic wounds harder to treat. Nowadays, medical treatment and management of diabetic wounds, which have a significant amputation rate, a high-frequency rate, and a high death rate, have become a global concern. Topical formulations have played a significant part in diabetic wound management and have been developed to achieve a number of features. Because of its significant biocompatibility, moisture retention, and therapeutic qualities, topical insulin has emerged as an appealing and feasible wound healing process effector. With a greater comprehension of the etiology of diabetic wounds, numerous functionalized topical insulins have been described and shown good outcomes in recent years, which has improved some diabetic injuries. The healing of wounds is a physiological phenomenon that restores skin integrity and heals damaged tissues. Insulin, a powerful wound-healing factor, is also used in several experimental and clinical studies accelerate healing of diverse injuries.

The Use of Fast-Acting Insulin Topical Solution on Skin to Promote Surgical Wound Healing in Cats

Wound healing is a complex biological process involving a coordinated sequence of events aimed at restoring tissue integrity and function. Recent advancements in wound care have introduced novel therapies, with topical insulin application emerging as a promising strategy for promoting tissue healing. This study, involving 60 female cats (n = 60) undergoing elective spaying, aimed to evaluate the effects of topical fast-acting insulin on the healing process of surgical wounds. Each surgical suture was divided into two regions: the control zone (Zcr) without insulin application and the study zone (Zst), where insulin was applied topically for 10 min every 24 h over eight consecutive days. Assessment of suture healing was conducted using an adapted scale at two time points post-surgery: T1 (day 2) and T2 (day 8). Statistically significant differences were registered in the final healing scale scores between Zcr and Zst (p < 0.022), as well as for the parameter of regional fluid (p-value = 0.017). Additionally, at T2, all Zst regions exhibited wound closure, whereas Zcr did not, although not in a statistically significant manner. The observed discrepancy at T2 between the Zcr and Zst regions may suggest a potential benefit of utilizing insulin. No side effects resulting from the insulin topical application performed by the tutors were recorded in the Zst suture group. This study represents the first exploration of the benefits of topical insulin application for surgical wound healing in cats.

Bioactive Insulin-Loaded Electrospun Wound Dressings for Localized Drug Delivery and Stimulation of Protein Expression Associated with Wound Healing

Effective therapy of wounds is difficult, especially for chronic, non-healing wounds, and novel therapeutics are urgently needed. This challenge can be addressed with bioactive wound dressings providing a microenvironment and facilitating cell proliferation and migration, ideally incorporating actives, which initiate and/or progress effective healing upon release. In this context, electrospun scaffolds loaded with growth factors emerged as promising wound dressings due to their biocompatibility, similarity to the extracellular matrix, and potential for controlled drug release. In this study, electrospun core-shell fibers were designed composed of a combination of polycaprolactone and polyethylene oxide. Insulin, a proteohormone with growth factor characteristics, was successfully incorporated into the core and was released in a controlled manner. The fibers exhibited favorable mechanical properties and a surface guiding cell migration for wound closure in combination with a high uptake capacity for wound exudate. Biocompatibility and significant wound healing effects were shown in interaction studies with human skin cells. As a new approach, analysis of the wound proteome in treated ex vivo human skin wounds clearly demonstrated a remarkable increase in wound healing biomarkers. Based on these findings, insulin-loaded electrospun wound dressings bear a high potential as effective wound healing therapeutics overcoming current challenges in the clinics.

Effectiveness of Topical Insulin Dressings in Management of Diabetic Foot Ulcers

BACKGROUND

Infected diabetic foot ulcers are always a problem for the surgeon, as well as, an economic burden upon the patient and state, in terms of increased hospital stay and cost of medications and dressings. Various methods have been devised for the treatment of infected wounds in history with varying results in different patients groups. The purpose of this study is to compare the effectiveness of topical insulin on the healing of diabetic foot ulcers with the conventional Pyodine^® povidone iodine dressing. Our objective was to compare effectiveness of topical insulin with conventional Pyodine^® povidone iodine dressings in frequency of healing of diabetic foot ulcers.

MATERIALS AND METHODS

It was a quasi-experimental study done at Pakistan Institute of Medical Sciences Islamabad over a period of 20 months from January 2015 to September 2016. One hundred ten patients were included in the study. Sampling technique used was non-probability consecutive. Patients were assigned into two groups, group A receiving treatment with solution of 30 International Units Insulin Regular in 30 ml of normal saline and group B receiving conventional dressing with normal saline. The wound were compared for both groups at the days 7, 14 and 21 for wound healing. Complete healing time of diabetic foot ulcers was determined from patients' followup visits in outpatient department. Data was by analyzed by SPSS 20.

RESULTS

A total of 110 patients were enrolled in the study. Patients were divided equally into both control and experimental groups. The mean age of the patients was 53.23 ± 6.21 years. The mean pre-treatment wound diameter was 4.81 ± 0.85 cm in the placebo group, while it was 4.84 ± 0.81 cm in the topical insulin group (CI 0.29-0.35, P = 0.875). The mean post-treatment wound diameter was 3.90 ± 0.76 cm in the placebo group, while it was 2.46 ± 0.57 cm in the topical insulin group (CI 0.44-0.58, P = 0.022). The mean wound difference was 0.91 ± 0.25 cm in the placebo group, while it was 2.4 ± 0.34 cm in the topical insulin group (CI 0.40-0.20, P = 0.041). The mean percent reduction in wound diameter was 19.2 ± 4.6% in the placebo group, while it was 49.7 ± 5.2% cm in the topical insulin group (CI 10.6-6.1, P = 0.001).

CONCLUSION

There was significant contraction seen in the size of the ulcer in both the study groups depicting the healing process.

Topical insulin application accelerates diabetic wound healing by promoting anti-inflammatory macrophage polarization

Besides regulating glucose levels, insulin has been reported to participate actively in many other functions, including modulating inflammatory reactions. In this study we investigated how topical insulin application would affect the diabetic wound healing process. We found that the excessive expression of insulin-degrading enzyme led to insufficient insulin levels in diabetic skin during wound healing, which ultimately reduced the recovery rate of diabetic wounds. We confirmed that topical insulin application could reverse the impaired inflammation reaction in the diabetic wound environment and promote healing of diabetic wounds. Our study revealed that insulin promoted apoptosis of neutrophils and subsequently triggered polarization of macrophages. Both in vivo and in vitro studies verified that insulin re-established phagocytosis function and promoted the process of phagocytosis-induced apoptosis in neutrophils. Furthermore, we found that insulin treatment also promoted efferocytosis of the apoptosed neutrophils by macrophages, and thus induced macrophages to change their polarization state from M1 to M2. In conclusion, our studies proved that the exogenous application of insulin could improve diabetic wound healing via the restoration of the inflammatory response.

Effects of Topical Insulin on Wound Healing: A Review of Animal and Human Evidences

Wound healing is a complex biological process that repairs damaged tissues and restores skin integrity. Insulin, a potent factor of wound healing, has been reported for nearly a century to induce rapid recovery of various wounds, as shown by numerous human and animal studies. Although many studies have addressed the healing effect of systemic insulin on burn wound, only few have investigated the efficacy of topical insulin. Thus, this study aimed to review evidence of the effects of topical insulin on wound healing, including on diabetic and non-diabetic wounds. The presented animal and clinical studies support that topical insulin improves wound healing through several mechanisms without causing side effects. Additionally, various wound dressings accelerate the wound healing with controlled and sustained delivery of bioactive insulin. Therefore, topical insulin has been appreciated in field of wound healing, and further studies are needed to improve our understanding of the role of insulin in the healing of various wounds.

Core-shell insulin-loaded nanofibrous scaffolds for repairing diabetic wounds

Patients with diabetes mellitus have up to a 15% lifetime risk of non-healing and poorly healing wounds. This work develops core-shell nanofibrous bioactive insulin-loaded poly-D-L-lactide-glycolide (PLGA) scaffolds that release insulin in a sustained manner for repairing wounds in diabetic rats. To prepare the biodegradable core-shell nanofibers, PLGA and insulin solutions were fed into two capillary tubes of different sizes that were coaxially electrospun using two independent pumps. The scaffolds sustainably released insulin for four weeks. The hydrophilicity and water-containing capacity of core-shell nanofibrous insulin/PLGA scaffolds significantly exceeded those of blended nanofibrous scaffolds. The nanofibrous core-shell insulin-loaded scaffold reduced the amount of type I collagen in vitro, increased the transforming growth factor-beta content in vivo, and promoted diabetic would repair. The core-shell insulin-loaded nanofibrous scaffolds prolong the release of insulin and promote diabetic wound healing.

Topical insulin-liposomal formulation in management of recurrent aphthous ulcers: A randomized placebo-controlled trial

AIM

To evaluate the effectiveness of topical insulin-liposomal gel in aphthous ulcer treatment.

METHODS

80 participants with minor aphthous ulcers were randomly divided to receive either topical insulin-liposomal gel or placebo gel (once daily) for 6 days. Assessment of outcomes included visual analog scale (VAS) for pain (primary outcome), and secondary outcomes included ulcer duration and impact of treatment on quality of life using the Oral Health Impact Profile 14 (OHIP-14). Testing of the outcomes was carried out at 1, 2, 3, 4 and 6 days after treatment for VAS and at 6 days for OHIP-14.

RESULTS

For pain scores, the test group showed a significant decrease by time, this was evident from day 1 (P < .001); at day 3, median and interquartile range (IQR) values were 0 (0-1). For the placebo group, a non-significant change by time was reported between baseline and day 1; at day 3, the median value was 7 (IQR, 7-9). The test group showed significantly lower mean duration than the placebo group (P < .001). OHIP-14 scores after 6 days showed that the test group had a significantly lower score than placebo (P < .001).

CONCLUSIONS

Topical insulin-liposomal formulation showed marked effectiveness in management of aphthous ulcers.

Coencapsulation of ISCs and MSCs Enhances Viability and Function of both Cell Types for Improved Wound Healing

Introduction

We previously demonstrated that insulin secreting cells (ISCs) accelerate healing of chronic wounds, and it is known that mesenchymal stem cells (MSCs) also accelerate wound healing. Here, we report that the combination of both cell types coencapsulated into a synthetic hydrogel dressing accelerates chronic wound healing 3 × faster than control and 2 × faster than each cell type delivered singly. Specifically, insulin released by ISCs activates the PI3/Akt pathway, which is vital to the function and survival of MSCs. MSCs in turn improve the viability and function of ISCs.

Materials and Methods

MSCs and/or rat islet tumor RIN-m cells were encapsulated into polyethylene glycol diacrylate hydrogel sheets and applied to 1 cm² full thickness excisional wounds on the dorsa of genetically diabetic male mice (BKS.Cg-m +/+Leprdb/J) in accordance with protocols approved by the Rutgers IACUC. Encapsulated cell viability was assessed using a LIVE/DEAD^® Viability/Cytotoxicity Kit. Akt phosphorylation, insulin, VEGF, and TGF-β1 secretion were assessed by ELISA. Animals were sacrificed on postoperative days 14 and 28 and wound tissue was collected for histological and western blot analysis.

Results

ISC:MSC combination groups had the highest levels of every secreted product and phosphorylated Akt, and closed wounds in 14 days, ISC-only or MSC-only groups closed wounds in 28 days, control groups closed wounds in 40 days. Further, ISC:MSC groups healed without intermediate scab or scar.

Conclusions

Combining MSCs with ISCs results in a more robust healing response than singly delivered cells, warranting further investigation of coencapsulation for MSC therapies.

Neurotensin, substance P, and insulin enhance cell migration

Neurotensin, substance P, and insulin have been demonstrated to improve wound healing in vivo. However, the mechanism behind their effect is still not fully understood. This study investigates the effects leading to enhanced scratch closure by these peptides in vitro. The skin keratinocyte cell line, HaCaT, was used to test scratch closure effects of the peptides and alterations of cytokine levels. HUVEC cells were used to test the angiogenic effect of the peptides. Furthermore, clinical isolates of Staphylococcus lugdunensis were used to examine the potential antimicrobial activity of each peptide. Our results demonstrate that neurotensin, substance P, and insulin had significant migratory effects in scratch assays were neurotensin had the lowest effect. Furthermore, we investigated use of the peptides in combination. When substance P was used in combination with neurotensin, the cell migratory capacity was decreased, and the peptides showed a negative correlation (r = -0.298, P < .001). Neurotensin and insulin significantly increased levels of monocyte chemoattractant protein-1 (P < .001) secreted from white blood cells, whereas substance P showed a tendency. Interestingly, neurotensin increased the level of monocyte chemoattractant protein-1 significantly compared to substance P (P < .01). Additionally, the peptides decreased TNFα mRNA levels (P < .001) in HaCaT cells, whereas only neurotensin and insulin decreased IL-8 mRNA (P < .001) but had no significant effect on IL-6 mRNA levels. Surprisingly, substance P increased IL-6 mRNA 9-fold (P < .001). Furthermore, we demonstrate that the peptides increased angiogenesis in the HUVEC cells (P < .001). Finally, S. lugdunensis isolates were not susceptible to the peptides. We demonstrate that the peptides worked differently on HaCaT cells, but substance P acted differently than neurotensin on cytokine levels expression as well as on migration of HaCaT cells. On the contrary, neurotensin and insulin worked similarly. All of these aspects are crucial for proper wound healing, and the results suggest multiple mechanisms for wound-healing properties of these peptides.

Insulin regulates multiple signaling pathways leading to monocyte/macrophage chemotaxis into the wound tissue

Wound healing is a complex process that involves sequential phases that overlap in time and space and affect each other dynamically at the gene and protein levels. We previously showed that insulin accelerates wound healing by stimulating faster and regenerative healing. One of the processes that insulin stimulates is an increase in monocyte/macrophage chemotaxis. In this study, we performed experiments in vivo and in vitro to elucidate the signaling transduction pathways that are involved in insulin-induced monocyte/macrophage chemotaxis. We found that insulin stimulates THP-1 cell chemotaxis in a dose-dependent and insulin receptor-dependent manner. We also show that the kinases PI3K-Akt, SPAK/JNK, and p38 MAPK are key molecules in the insulin-induced signaling pathways that lead to chemoattraction of the THP-1 cell. Furthermore, both PI3K-Akt and SPAK/JNK signaling involve Rac1 activation, an important molecule in regulating cell motility. Indeed, topical application of Rac1 inhibitor at an early stage during the healing process caused delayed and impaired healing even in the presence of insulin. These results delineate cell and molecular mechanisms involved in insulin-induced chemotaxis of monocyte/macrophage, cells that are critical for proper healing.

Summary: Insulin regulates multiple signaling pathways leading to monocyte/macrophage chemotaxis into the wound tissue, involving -Akt, SPAK/JNK, and p38 MAPK which in turn are involved in Rac1 activation. Furthermore, these results augment our understanding of the insulin-regulated wound inflammatory response.

Effects of Local Use of Insulin on Wound Healing in Non-diabetic Patients

Background

Clinical trials have shown the positive effects of local insulin therapy in the formation of new vessels and fibrosis in acute and chronic diabetic wounds without major adverse effects.

Objective

The aim of this study was to investigate the effects of local insulin use on wound healing in non-diabetic patients.

Methods

A randomized, split-plot, double-blind, placebo-controlled trial was conducted. Ten non-diabetic patients with full-thickness acute wounds were recruited (5 due to trauma, 3 to burns, and 2 to pressure). All wounds received standard bedside treatment. Each wound was divided into 2 zones. One side received a standard care plus insulin, while the other received standard care plus injection of saline solution. A biopsy specimen was taken from both sites on days 0 and 14. The amount of blood vessel growth and the percentage of fibrosis were evaluated.

Results

A significant difference in the number of new vessels was observed on the insulin-treated site (70.6 [29.21]) compared to saline only (26.5 [34.3]; P < .04). The percentage of fibrosis (insulin 34.7 [28.02] vs saline 27.8 [29.9]) showed no significant difference. No adverse events related to the study occurred. The clinical implications of this study are considerable in terms of the formation of blood vessels but not fibrosis.

Conclusion

We suggest that local insulin administration is a safe therapeutic option for angiogenesis in wounds of non-diabetic patients.

Effects of insulin on wound healing: A review of animal and human evidences

AIMS

Several studies have indicated that insulin that is used in reducing blood glucose is also affective on wound healing by various mechanisms. To understand the outcomes of insulin therapy on wound healing, a meta-analysis and systematic review was performed.

MAIN METHODS

The Cochrane library, PubMed, and Science Direct were searched for the literature published from January the 1st 1990 to September the 30th 2016. Twelve animals and nine clinical studies were included. A quantitative and qualitative review was performed on the clinical trials and the animal studies were comprehensively overviewed. Statistical analysis for development of granulation tissue, microvessel density, and time of healing was conducted in this systematic review.

KEY FINDINGS

The animal studies revealed that treatment with topical insulin lead to faster wound contraction and re-epithelialization. Meta-analysis of wound studies revealed that insulin therapy is significantly favored for growth of granulation tissue. Based on these findings, insulin enhanced development of granulation tissue on day 7 after treatment. The meta-analysis studies indicated significant reduction in time of healing in the patients treated with insulin. These studies also disclosed that the new vessels were observable from five days after injection in the treated group, compared to the control animals that developed significantly at later stage.

SIGNIFICANCE

Insulin is a low cost growth factor and can be considered as a therapeutic agent in wound healing. However, further studies are necessary to gain a better understanding of the role of insulin in wound healing.

Efficacy of topical insulin in wound healing: A preliminary systematic review and meta-analysis of randomized controlled trials

Topical insulin has been shown to promote wound healing in various studies. Considering the absence of a systematic review and quantitative synthesis on the same, the present study was carried out. Using an appropriate search strategy, electronic databases were searched for randomized controlled trials that have compared topical application of insulin in wounds with normal saline. Standardize mean differences were calculated for the following outcome measures: healing rate of ulcers/wound, percent granulation tissue growth, microvessel density, time to heal, wound area and ulcer severity score. Cochrane's risk of bias tool was used for each of the studies and RevMan 5.3 software was used to generate the pooled estimates and Forest plots. The quality of evidence was assessed by the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) working group approach. A total of 8 studies were found eligible to be included in this review and 7 for the meta-analysis. The pooled estimates were as follows: healing rate-0.04 [-1.38, 1.46]; percent granulation tissue-10.99 [-10.07, 32.06], microvessel density-3.01 [-1.67, 7.69] and wound area--6.59 [-9.7, -3.48]. There was only one study for each of the following outcome measures: time to heal and ulcer severity score. Hence, pooling of the results was not attempted for these outcome measures. The studies conducted in this field were preliminary and it was difficult to draw any conclusion regarding the use of insulin topically for wound healing.

Efeito da estimulação elétrica de alta voltagem e insulina tópica em lesão cutânea experimental

RESUMO O objetivo deste estudo foi avaliar o efeito da estimulação elétrica de alta voltagem (EEAV) catódica, associada à insulina tópica, em lesão tegumentar de ratos. Para isso, foram utilizados 42 ratos Wistar (240±30 g), submetidos a retirada cirúrgica de 1 cm2 de pele do dorso em seis grupos (n=7), tratados por sete dias consecutivos: controle (C), estimulação elétrica placebo (EP), estimulação elétrica catódica (EE), insulina tópica (IT), insulina placebo (IP) e EEAV associada a insulina tópica (EE+I). A EEAV foi administrada 24 horas após a cirurgia, 30 minutos por dia, com frequência de 100 Hz e voltagem média de 60 V, mantida no limiar motor. Áreas das lesões foram registradas macroscopicamente no primeiro, quarto e oitavo dia, sendo submetidas a tratamento histológico para inclusão em paraplast® e coloração em hematoxilina e eosina. A epitelização e o perfil numérico das células foram obtidos por análises histométricas. Utilizou-se o teste de Shapiro-Wilk e ANOVA one-way seguida de Bonferrone (p<0,05). Observou-se redução significativa na área da lesão no oitavo dia de tratamento, nos grupos EE e EE+I em relação aos demais grupos. A reepitelização não diferiu entre os grupos, mas a distância entre as bordas da lesão foi menor nos grupos EE e EE+I. Nesses grupos houve aumento significativo (p<0,05) no número de fibroblastos e diminuição de leucócitos. Pode-se concluir que a EEAV catódica acelerou o processo de reparação da lesão, não demonstrando efeito adicional com a aplicação da insulina tópica.

Clinical study on local application of low-dose insulin for promoting wound healing after operation for deep burns

Transplanted free skin flaps are often needed to treat deep burns; their survival, however, is less than optimal. This study examined whether local low-dose insulin injections can promote flap survival and wound healing after surgery. A total of 165 patients who underwent free skin flap transplantation for simple deep burns were enrolled in the study and divided into 5 groups of 33 patients each: Blank control group (no local subcutaneous drug injections), saline control group (saline injections), low-dose insulin group (0.5 units regular insulin injections), medium-dose group (1.0 units regular insulin injections) and high-dose group (2.0 units regular insulin injections). Wound healing and flap survival conditions were assessed and compared among groups. The best wound healing rate found was that of the low-dose insulin injection group where all the parameters measured improved significantly: The healing time was shorter; the blood flow volume, the flap survival, the number of fibroblasts and new vessels increased; the re-epithelialization occurred faster; the infiltration of inflammatory cells was reduced; the expression levels of heat shock protein-90, vascular endothelial growth factor, transforming growth factor-β and interleukin-1 were higher; and the plasma glucose levels only fluctuated slightly. The results clearly demonstrate that a local low-dose insulin regime after flap transplantation can accelerate the healing time and improve the surgical outcome without exerting detrimental secondary effects on the glucose plasma level of deep burn patients.

Non-diabetic clinical applications of insulin

BACKGROUND

Introducing a new drug to the market is a time-consuming process, is complex, and involves consumption of a lot of resources. Therefore, discovering new uses for the old drugs (i.e. drug repurposing) benefits the patients by providing them time-tested drugs. With developments in insulin therapy still happening, it is worth keeping up to date on trends in the use of this powerful glucose-lowering agent. The aim of this article is to explore the potential non-diabetic clinical applications of insulin.

METHODS

Literature survey was carried out through the various scientific journals publishing experimental and clinical research papers regarding the diverse applications of insulin other than in diabetes mellitus. These applications include both therapeutic as well as diagnostic uses of insulin. The relevant information collected from these publications was paraphrased in the present paper.

RESULTS

On studying the literature, the non-diabetic uses of insulin include the following: wound healing, parenteral nutrition, antiaging, body building, cardioprotection in acute coronary syndromes, insulin tolerance test to test the hypothalamo-pituitary-adrenal axis functioning, cell culture, cancer treatment, organ preservation, and management of septic shock, calcium channel, β-blocker overdose and other critical illnesses in intensive care units.

CONCLUSIONS

This review attempts to survey some interesting new applications of insulin other than in diabetes mellitus.

Wound Healing Concepts in Clinical Practice of OMFS

BACKGROUND

Wound healing is a complex and dynamic process and a thorough knowledge of the basics of physiology of wound healing is a must to implement principles of chronic wound care. Understanding wound healing at multiple levels-biochemical, physiologic, cellular and molecular provides the surgeon with a framework for basing clinical decisions aimed at optimizing the healing response.

OBJECTIVE

This review article describes the classification of wounds and aims to highlight the fundamentals of wound repair, enumerating the dressings used commonly and also, the newer concepts of wound healing.

MATERIALS AND METHODS

Search engines and medical databases were tapped to gather information on the subject. Search words employed were "Wounds", "wounds in OSMF", "Wound healing", "Repair", "Dressings in OMFS".

RESULTS

The search resulted in total of 153 articles which we reviewed to add to the literature the concepts of wound healing and to throw some light on recent advances in wound care.

CONCLUSIONS

Wound healing remains a challenging clinical problem and correct, efficient wound management is essential to positively influence the wound healing course and reduce potential complications.

Effect of local insulin injection on wound vascularization in patients with diabetic foot ulcer

The aim of the present study was to investigate the effect of local insulin injection on granulation tissue formation in the wounds of patients with diabetic foot ulcer. Thirty-two patients with diabetic foot ulcer were randomly divided into an insulin (n=18) and a control (n=14) group. In the diabetic foot ulcer wound, the insulin group were administered insulin and the control group were administered an equal volume of saline. Prior to injection and at 0.5, 1.0, 2.0 and 4.0 h after injection, the fingertip blood glucose levels were determined. The growth of granulation tissue was assessed continuously for 12 days. Wound tissue was harvested at 0, 5, 7 and 12 days for the detection of CD34 expression by immunohistochemistry. The microvessel density (MVD) was calculated. No significant difference in the fasting blood glucose level was found between the two groups at any time-point (P>0.05). Growth of granulation tissue in the insulin group was more marked from 7 days after local insulin injection (24.87±0.24) and was significantly different from that in the control group (18.66±0.45) (P<0.01). New vessels were observed in the insulin group 3 days after insulin injection; however, there was no significant difference in MVD compared with the control group (P>0.05). The MVD in the insulin group increased markedly from 5 days after treatment, and the difference between the two groups was significant (P<0.01). In conclusion, local injection of insulin into the base of a diabetic foot ulcer has a significant effect on systemic blood glucose and may promote wound healing by improving the growth of granulation tissue.

Release of insulin from PLGA-alginate dressing stimulates regenerative healing of burn wounds in rats

Burn wound healing involves a complex set of overlapping processes in an environment conducive to ischaemia, inflammation and infection costing $7.5 billion/year in the U.S.A. alone, in addition to the morbidity and mortality that occur when the burns are extensive. We previously showed that insulin, when topically applied to skin excision wounds, accelerates re-epithelialization and stimulates angiogenesis. More recently, we developed an alginate sponge dressing (ASD) containing insulin encapsulated in PLGA [poly(D,L-lactic-co-glycolic acid)] microparticles that provides a sustained release of bioactive insulin for >20 days in a moist and protective environment. We hypothesized that insulin-containing ASD accelerates burn healing and stimulates a more regenerative, less scarring healing. Using heat-induced burn injury in rats, we show that burns treated with dressings containing 0.04 mg insulin/cm(2) every 3 days for 9 days have faster closure, a higher rate of disintegration of dead tissue and decreased oxidative stress. In addition, in insulin-treated wounds, the pattern of neutrophil inflammatory response suggests faster clearing of the burned dead tissue. We also observe faster resolution of the pro-inflammatory macrophages. We also found that insulin stimulates collagen deposition and maturation with the fibres organized more like a basket weave (normal skin) than aligned and cross-linked (scar tissue). In summary, application of ASD-containing insulin-loaded PLGA particles on burns every 3 days stimulates faster and more regenerative healing. These results suggest insulin as a potential therapeutic agent in burn healing and, because of its long history of safe use in humans, insulin could become one of the treatments of choice when repair and regeneration are critical for proper tissue function.

The Application of Negative Pressure Wound Therapy with Installation in Diabetic Foot Associated with Phlegmon

The negative pressure wound therapy in the treatment of diabetic foot ulcers was used successfully for many years. In the case of complications associated with infection by this type of wound treatment to give very good results. From many years of sustained research on a device that could combine the advantages of the negative pressure wound therapy and drainage flow. Finally, in the last year, the first V.A.C. Ulta (KCI, USA) devices were included to the Polish hospital departments. In this paper we present a case of a patient of successfully using a negative pressure wound therapy with installation via a set of V.A.C. Ulta in the ischemic diabetic foot syndrome complicated by phlegmon and tissue necrosis. The patient was treated in stages. In first stage was performed angioplasty of critically stenosis of the superficial femoral artery segment. Secondly, the resection of the necrotic bone revised fingers and forefoot was conducted, and in the third step the negative pressure wound therapy with installation was used. Finally, the wound was closed by the intermediate thickness skin graft. The total duration of treatment was 21 days. The patient in good general condition with a completely healed wound was discharged. Currently, after the supply with orthopedic equipment, patient regained full mobility.

A pilot trial using topical regular crystalline insulin vs. aqueous zinc solution for uncomplicated cutaneous wound healing: Impact on quality of life

When wounds are treated with regular insulin, they are also being treated with zinc; used in the formula to crystallize insulin molecules. It is not clear if regular insulin-accelerated wound healing is due to insulin, the zinc it contains, or both. Thus, we aimed to compare topical regular crystalline insulin (containing zinc) vs. aqueous zinc chloride solution to controls, on healing of open uncomplicated cutaneous wounds. In this randomized controlled pilot study, 90 nondiabetic patients were randomly assigned to one of three groups depending on the twice daily applications received; group I: regular insulin; group II: aqueous zinc chloride solution, and group III: 0.9% saline (control). A questionnaire was used to determine the effect of wounds on the quality of life. Both topical regular crystalline insulin (containing zinc) and aqueous zinc chloride solution enhanced healing of uncomplicated cutaneous wounds of nondiabetic patients, than control (p < 0.001), and hence improved patients' quality of life. However, regular insulin showed better results than aqueous zinc solution (p = 0.015), probably due to synergistic effect between insulin and zinc of its formulation. Healing rate was significantly higher in acute than chronic wounds (p < 0.001), in those ≤40 years than those >40 (p = 0.004), and in upper body wounds than lower body (p = 0.015).

Insulin and wound healing

Skin is a dynamic and complex organ that relies on the interaction of different cell types, biomacromolecules and signaling molecules. Injury triggers a cascade of events designed to quickly restore skin integrity. Depending on the size and severity of the wound, extensive physiological and metabolic changes can occur, resulting in impaired wound healing and increased morbidity resulting in higher rates of death. While wound dressings provide a temporary barrier, they are inherently incapable of significantly restoring metabolic upsets, post-burn insulin resistance, and impaired wound healing in patients with extensive burns. Exogenous insulin application has therefore been investigated as a potential therapeutic intervention for nearly a century to improve wound recovery. This review will highlight the important achievements that demonstrate insulin's ability to stimulate cellular migration and burn wound recovery, as well as providing a perspective on future therapeutic applications and research directions.

Local use of insulin in wounds of diabetic patients: higher temperature, fibrosis, and angiogenesis

BACKGROUND

Clinical trials have shown the effectiveness of systemic and local insulin therapy in improving wound healing. Diabetic wounds remain a challenge for healthcare providers. Impaired angiogenesis and reduced granulation tissue formation contribute to inadequate wound healing. The aim of this study was to investigate the effect of local insulin administration in acute and chronic diabetic wounds.

METHODS

Eight diabetic patients presenting with full-thickness wounds, of different causes, were included in this study. Five wounds were due to necrobiosis, one to trauma, and two to postneoplasm resection. All wounds were treated with regular bedside treatment. In addition, half of the wound surface was treated with insulin and the other half did not receive insulin. Thermographic and biopsy specimens of the two sides were obtained on days 0 and 14. The presence of fibrosis, change in temperature, and amount of blood were evaluated.

RESULTS

Significant differences in the number of vessels were observed on the insulin-treated side (96 ± 47) when compared with the no-insulin side (32.88 ± 45) (p < 0.026). The percentage of fibrosis (insulin: 44.42 ± 30.42 percent versus no insulin: 12.38 ± 36.17 percent; p < 0.047) and the mean temperature (insulin: 1.27 ± 1.12°C versus no-insulin: 0.13 ± 1.22°C; p < 0.001) were also significantly different between sides. No adverse events related to the study occurred.

CONCLUSION

The use of local insulin improves the formation of new blood vessels, increases fibrosis, and correlates with increased temperature.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

Insulin and hypertonic glucose in the management of aseptic fat liquefaction of post-surgical incision: a meta-analysis and systematic review

A meta-analysis and systematic review assessing randomised controlled trials (RCTs) was sought to determine whether subcutaneous injection of insulin with hypertonic glucose promotes healing in postoperative incisions with aseptic fat liquefaction. We searched the Cochrane library, Pubmed, EMBASE, National Science Digital Library (NSDL) and China Biological Medicine Database (CBMdisc) for literature published from 1 January 1990 to 30 September 2011. RCTs that evaluated subcutaneous injection of insulin with hypertonic glucose as a treatment for postoperative wound with fat liquefaction were sought. Wound healing was the primary endpoint. Jadad score and Cochrane Collaboration's tool were used for assessing quality of studies and risk of bias. We abstracted data regarding time to wound healing, cost and adverse effects. The random-effects inverse variance model was used for all analyses using weighted mean difference and 95% confidence interval. Eight trials (414 participants) were identified that met the inclusion criteria. Subcutaneous injection of insulin with hypertonic glucose significantly reduces time to healing by 6·33 days compared with conventional drainage, with less cost. There was no report concerning adverse effects. Subcutaneous injection of insulin with hypertonic glucose may improve the healing process in postoperative wounds with aseptic fat liquefaction.

Recent advances in topical wound care

There are a wide variety of dressing techniques and materials available for management of both acute wounds and chronic non-healing wounds. The primary objective in both the cases is to achieve a healed closed wound. However, in a chronic wound the dressing may be required for preparing the wound bed for further operative procedures such as skin grafting. An ideal dressing material should not only accelerate wound healing but also reduce loss of protein, electrolytes and fluid from the wound, and help to minimize pain and infection. The present dictum is to promote the concept of moist wound healing. This is in sharp contrast to the earlier practice of exposure method of wound management wherein the wound was allowed to dry. It can be quite a challenge for any physician to choose an appropriate dressing material when faced with a wound. Since wound care is undergoing a constant change and new products are being introduced into the market frequently, one needs to keep abreast of their effect on wound healing. This article emphasizes on the importance of assessment of the wound bed, the amount of drainage, depth of damage, presence of infection and location of wound. These characteristics will help any clinician decide on which product to use and where,in order to get optimal wound healing. However, there are no ‘magical dressings’. Dressings are one important aspect that promotes wound healing apart from treating the underlying cause and other supportive measures like nutrition and systemic antibiotics need to be given equal attention.

Sustained prolonged topical delivery of bioactive human insulin for potential treatment of cutaneous wounds

Skin damaged by heat, radiation, or chemical exposure is difficult to treat and slow to heal. Indeed full restoration of the tissue is difficult to obtain. Sub-dermal insulin injection was recently shown to stimulate wound healing of the skin by accelerating wound closure, stimulating angiogenesis and inducing a regenerative process of healing. We have developed a topical delivery vehicle that is capable of releasing therapeutic levels of bioactive insulin for several weeks with the potential to stimulate and sustain healing. By encapsulating the crystalline form of insulin within poly(d,l-lactide-co-glycolide) microspheres, we succeeded in stabilizing and then releasing bioactive insulin for up to 25 days. To measure bioactivity we used Rat L6 myofibroblasts, stimulated them with this slow release insulin and determined activation of the receptors on the cell surface by quantifying AKT phosphorylation. There was only a minor and gradual decrease in AKT phosphorylation over time. To determine whether the slow release insulin could stimulate keratinocyte migration, wounding was simulated by scratching confluent cultures of human keratinocytes (HaCaT). Coverage of the scratch "wounds" was significantly faster in the presence of insulin released from microspheres than in the insulin-free control. Extended and sustained topical delivery of active insulin from a stable protein crystal-based reservoir shows promise in promoting tissue healing.

Novel use of insulin in continuous-instillation negative pressure wound therapy as "wound chemotherapy"

Negative pressure wound therapy (NPWT) is frequently employed in the treatment of complex wounds. A variety of wound chemotherapeutic agents such as insulin, which acts as a growth factor, may prove helpful in treatment as well. We present a case report in which insulin was used as a chemotherapeutic agent in continuous-instillation NPWT. To our knowledge, this is the first report in the literature describing this method of delivery.

The ubiquitous role of zinc in health and disease

OBJECTIVE

To review zinc physiology and pathophysiology and the importance of zinc toxicity and deficiency in veterinary patients.

DATA SOURCES

A review of human and veterinary medical literature.

HUMAN DATA SYNTHESIS

There is a significant amount of original research in humans and animals on the role of zinc in multiple organ systems. There is also significant data available on human patients with zinc abnormalities.

VETERINARY DATA SYNTHESIS

Zinc deficiency has been studied in dogs with genetic disease and dietary deficiency leading to dermatological disease and immune deficiency. Zinc toxicity has been described after ingestion of metallic foreign bodies containing zinc.

CONCLUSIONS

Historically, the role of zinc in health and disease has been studied through patients with toxicity or severe deficiency with obvious clinical signs. As the ubiquitous contribution of zinc to structure and function in biological systems was discovered, clinically significant but subtle deficiency states have been revealed. In human medicine, mild zinc deficiencies are currently thought to cause chronic metabolic derangement leading to or exacerbating immune deficiency, gastrointestinal problems, endocrine disorders, neurologic dysfunction, cancer, accelerated aging, degenerative disease, and more. Determining the causal relationships between mild zinc deficiency and concurrent disease is complicated by the lack of sensitive or specific tests for zinc deficiency. The prevalence of zinc deficiency and its contribution to disease in veterinary patients is not well known. Continued research is warranted to develop more sensitive and specific tests to assess zinc status, to determine which patients are at risk for deficiency, and to optimize supplementation in health and disease.

Nanodiamond-insulin complexes as pH-dependent protein delivery vehicles

Enhanced specificity in drug delivery aims to improve upon systemic elution methods by locally concentrating therapeutic agents and reducing negative side effects. Due to their robust physical properties, biocompatibility and drug loading capabilities, nanodiamonds serve as drug delivery platforms that can be applied towards the elution of a broad range of therapeutically-active compounds. In this work, bovine insulin was non-covalently bound to detonated nanodiamonds via physical adsorption in an aqueous solution and demonstrated pH-dependent desorption in alkaline environments of sodium hydroxide. Insulin adsorption to NDs was confirmed by FT-IR spectroscopy and zeta potential measurements, while both adsorption and desorption were visualized with TEM imaging, quantified using protein detection assays and protein function demonstrated by MTT and RT-PCR. NDs combined with insulin at a 4:1 ratio showed 79.8+/-4.3% adsorption and 31.3+/-1.6% desorption in pH-neutral and alkaline solutions, respectively. Additionally, a 5-day desorption assay in NaOH (pH 10.5) and neutral solution resulted in 45.8+/-3.8% and 2.2+/-1.2% desorption, respectively. MTT viability assays and quantitative RT-PCR (expression of Ins1 and Csf3/G-csf genes) reveal bound insulin remains inactive until alkaline-mediated desorption. For applications in sustained drug delivery and therapy we have developed a therapeutic protein-ND complex with demonstrated tunable release and preserved activity.

Cell and molecular mechanisms of keratinocyte function stimulated by insulin during wound healing

BACKGROUND

Regenerative wound repair is a goal of modern medicine. This is important not only for the local repair but also for its beneficial effect to systemic physiological processes. When wounds become chronic, individuals are susceptible to generalized inflammatory cascades that can affect many organs and even lead to death. Skin is the most commonly injured tissue, and its proper repair is important for reestablishment of its barrier function.

RESULTS

We show here that insulin, when topically applied to skin excision wounds, accelerates re-epithelialization and stimulates "maturation" of the healing tissue. These effects are dependent on the insulin receptor but independent of EGF/EGF-R; PI3K-Akt-Rac1 signaling pathways are critically involved, and healing is alpha3 and LN332-dependent.

CONCLUSION

Insulin has great potential for the treatments of chronic wounds in which re-epthelialization is impaired. Understanding of the pathways induced by insulin is important for the development of analog molecules that function strictly in healing. Because of its long history of safe use in humans for decades, this protein may prove to be a powerful therapy without major adverse effects.

The year in burns 2007

In the year 2007, approximately 1000 original burn research articles were published in scientific journals using the English language. This article reviews approximately 90 of these which were deemed by the author to be the most important in terms of clinical burn care. Relevant topics include epidemiology, wound characterisation, critical care physiology, inhalation injury, infection, metabolism and nutrition, psychological considerations, pain management, rehabilitation, and burn reconstruction. Each selected article is mentioned briefly with editorial comment.