Cell and molecular mechanisms of insulin-induced angiogenesis

GPER deficiency impedes murine myocutaneous revascularization and wound healing

Estrogens regulate numerous physiological and pathological processes, including wide-ranging effects in wound healing. The effects of estrogens are mediated through multiple estrogen receptors (ERs), including the classical nuclear ERs (ERα and ER β ), that typically regulate gene expression, and the 7-transmembrane G protein-coupled estrogen receptor (GPER), that predominantly mediates rapid "non-genomic" signaling. Estrogen modulates the expression of various genes involved in epidermal function and regeneration, inflammation, matrix production, and protease inhibition, all critical to wound healing. Our previous work demonstrated improved myocutaneous wound healing in female mice compared to male mice. In the current study, we employed male and female GPER knockout mice to investigate the role of this estrogen receptor in wound revascularization and tissue viability. Using a murine myocutaneous flap model of graded ischemia, we measured real-time flap perfusion via laser speckle perfusion imaging. We conducted histologic and immunohistochemical analyses to assess skin and muscle viability, microvascular density and vessel morphology. Our results demonstrate that GPER is crucial in wound healing, mediating effects that are both dependent and independent of sex. Lack of GPER expression is associated with increased skin necrosis, reduced flap perfusion and altered vessel morphology. These findings contribute to understanding GPER signaling in wound healing and suggest possible therapeutic opportunities by targeting GPER.

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.

Efficacy of the Novel Formulation of Topical Liothyronine and Liothyronine-insulin in Mild to Moderate Diabetic Foot Ulcer: A Randomized, Triple-blind Clinical Trial

BACKGROUND

Diabetic foot ulcer (DFU) is one of the challenging complications of chronic diabetes.

OBJECTIVE

The study aimed to investigate whether liothyronine (T3) and liothyronineinsulin (T3/Ins) topical preparations could significantly reduce the healing time of DFU.

METHODS

A prospective, randomized, placebo-controlled, patient-blinded clinical trial was conducted on patients with mild to moderate DFU, over a lesion area of no greater than 100 cm2. The patients were randomized to receive T3, T3/Ins, or honey cream 10% as the routine of care twice a day. Patients were examined for tissue healing weekly for 4 weeks, or until the total lesion clearance was observed, whichever was earlier.

RESULTS

Of 147 patients with DFUs, 78 patients (26 per group) completed the study and were included in the final evaluation. At the time of study termination, all participants in each of the T3 or T3/Ins groups were free of symptoms based on the REEDA score, while about 40% of participants in the control group were detected with each of grades 1, 2, or 3. A significant difference was observed on days 7, 14, and 21 of consumption of topical preparations (p-value < 0.001). The mean time to complete wound closure in the routine care group was about 60.6 days, while it was 15.9 and 16.4 days in T3 and T3/Ins groups, respectively. Within the T3 and T3/Ins groups, significant earlier wound closure was detected at day 28 (p-value < 0.001).

CONCLUSION

T3 or T3/Ins topical preparations are effective for wound healing and acceleration of wound closure in mild to moderate DFUs.

Local Insulin Improves Wound Healing: A Systematic Review and Bayesian Network Meta-Analysis

BACKGROUND

Wounds are a significant health issue, and reliable and safe strategies to promote repair are needed. Clinical trials have demonstrated that local insulin promotes healing in acute and chronic wounds (ie, reductions of 7% to 40% versus placebo). However, the trials' sample sizes have prevented drawing solid conclusions. Furthermore, no analysis has focused on safety concerns (ie, hypoglycemia). Under the hypothesis that local insulin promotes healing through proangiogenic effects and cellular recruitment, the aim of this systematic review and network meta-analysis (NMA) was to assess its safety and relative effectiveness using a Bayesian approach.

METHODS

Medline, CENTRAL, Embase, Scopus, LILACS, and gray literature sources were searched for human studies assessing the local use of insulin versus any comparator since inception to October of 2020. Data on glucose changes and adverse events, wound and treatment characteristics, and healing outcomes were extracted, and an NMA was conducted.

RESULTS

A total of 949 reports were found, of which 23 ( n = 1240 patients) were included in the NMA. The studies evaluated six different therapies, and most comparisons were against placebo. NMA showed -1.8 mg/dL blood glucose level change with insulin and a lack of reported adverse events. Statistically significant clinical outcomes identified include reduction in wound size (-27%), increased healing rate (23 mm/day), reduction in Pressure Ulcer Scale for Healing scores (-2.7), -10 days to attain complete closure, and an odds ratio of 20 for complete wound closure with insulin use. Likewise, significantly increased neoangiogenesis (+30 vessels/mm 2 ) and granulation tissue (+25%) were also found.

CONCLUSION

Local insulin promotes wound healing without significant adverse events.

Protamine as a barrier against the angiogenic effect of insulin: a possible role of apelin

Insulin is proved to have angiogenic ability thereby may worsen the diabetic retinopathy (DR) progression. Insulin also triggers the expression of endogenous angiogenic peptide, apelin. Since protamine was introduced as an inhibitor of the apelin receptor, we hypothesized that use of protaminated insulin instead of non-protaminated insulin can decrease the negative role of insulin in progression of DR. Firstly, the incidence of DR was compared among three diabetic patient groups: an oral medication, non-protaminated insulin, and protaminated insulin (PIns). Proliferation and migration rate of HUVECs was measured after insulin, apelin, and protamine exposure. In clinical study, the chance of developing DR was 8.5 and 4.1 times higher in insulin group and PIns groups compared with oral group respectively. Insulin group had a chance of 9.5-folds of non-proliferative DR compared to oral group. However, the difference of non-proliferative DR between PIns and oral group wasn't significant. In-vitro tests showed that concomitant use of insulin and apelin increases viability and migratory potential of HUVECs. However, protamine could reverse this effect. Protamine present in some insulins might show a promising protective role against diabetic retinopathy. Thus, protaminated insulins may be preferable in the treatment of diabetes.

Mussel bioinspired, silver-coated and insulin-loaded mesoporous polydopamine nanoparticles reinforced hyaluronate-based fibrous hydrogel for potential diabetic wound healing

Diabetes wounds take longer to heal due to extended inflammation, decreased angiogenesis, bacterial infection, and oxidative stress. These factors underscore the need for biocompatible and multifunctional dressings with appropriate physicochemical and swelling properties to accelerate wound healing. Herein, insulin (Ins)-loaded, and silver (Ag) coated mesoporous polydopamine (mPD) nanoparticles were synthesized (Ag@Ins-mPD). The nanoparticles were dispersed into polycaprolactone/methacrylated hyaluronate aldehyde dispersion, electrospun to form nanofibers, and then photochemically crosslinked to form a fibrous hydrogel. The nanoparticle, fibrous hydrogel, and nanoparticle-reinforced fibrous hydrogel were characterized for their morphological, mechanical, physicochemical, swelling, drug-release, antibacterial, antioxidant, and cytocompatibility properties. The diabetic wound reconstruction potential of nanoparticle-reinforced fibrous hydrogel was studied using BALB/c mice. The results indicated that Ins-mPD acted as a reductant to synthesize Ag nanoparticles on their surface, held antibacterial and antioxidant potential, and their mesoporous properties are crucial for insulin loading and sustained release. The nanoparticle-reinforced scaffolds were uniform in architecture, porous, mechanically stable, showed good swelling, and possessed superior antibacterial, and cell-responsive properties. Furthermore, the designed fibrous hydrogel scaffold demonstrated good angiogenic, anti-inflammatory, increased collagen deposition, and faster wound repair capabilities, therefore, it could be used as a potential candidate for diabetic wound treatment.

Derivation of Human Extraembryonic Mesoderm-like Cells from Primitive Endoderm

In vitro modeling of human peri-gastrulation development is a valuable tool for understanding embryogenetic mechanisms. The extraembryonic mesoderm (ExM) is crucial in supporting embryonic development by forming tissues such as the yolk sac, allantois, and chorionic villi. However, the origin of human ExM remains only partially understood. While evidence suggests a primitive endoderm (PrE) origin based on morphological findings, current in vitro models use epiblast-like cells. To address this gap, we developed a protocol to generate ExM-like cells from PrE-like cell line called naïve extraembryonic endoderm (nEnd). We identified the ExM-like cells by specific markers (LUM and ANXA1). Moreover, these in vitro-produced ExM cells displayed angiogenic potential on a soft matrix, mirroring their physiological role in vasculogenesis. By integrating single-cell RNA sequencing (scRNAseq) data, we found that the ExM-like cells clustered with the LUM/ANXA1-rich cell populations of the gastrulating embryo, indicating similarity between in vitro and ex utero cell populations. This study confirms the derivation of ExM from PrE and establishes a cell culture system that can be utilized to investigate ExM during human peri-gastrulation development, both in monolayer cultures and more complex models.

Smart microneedle patches for wound healing and management

The number of patients with non-healing wounds is generally increasing globally, placing a huge social and economic burden on every country. The complexity of the wound-healing process remains a major health challenge despite the numerous studies that have been reported on conventional wound dressings. Therefore, a therapeutic system that combines diagnostic and therapeutic modalities is essential to monitor wound-related biomarkers and facilitate wound healing in real time. Microneedles, as a multifunctional platform, are promising for transdermal diagnostics and drug delivery. Their advantages are mainly reflected in painless transdermal drug delivery, good biocompatibility, and ease of self-administration. In this work, we review recent advances in the use of microneedle patches for wound healing and monitoring. The paper first provides a brief overview of the skin structure and the wound healing process, and then discusses the current state of research and prospects for the development of wound-related biomarkers and their real-time monitoring based on microneedle sensors. It summarizes the current state of research based on the unique design of microneedle patches, including biomimetic, conductive, and environmentally responsive, to achieve wound healing. It further summarizes the prospects for the application of different microneedle-based drug delivery modalities and drug delivery substances for wound healing, due to their superior transdermal drug delivery advantages. It concludes with challenges and expectations for the use of smart microneedle patches for wound healing and management.

The impact of aging and physical training on angiogenesis in the musculoskeletal system

Angiogenesis is the physiological process of capillary growth. It is strictly regulated by the balanced activity of agents that promote the formation of capillaries (pro-angiogenic factors) on the one hand and inhibit their growth on the other hand (anti-angiogenic factors). Capillary rarefaction and insufficient angiogenesis are some of the main causes that limit blood flow during aging, whereas physical training is a potent non-pharmacological method to intensify capillary growth in the musculoskeletal system. The main purpose of this study is to present the current state of knowledge concerning the key signalling molecules implicated in the regulation of skeletal muscle and bone angiogenesis during aging and physical training.

Cholesterol Paradigm and Beyond in Atherosclerotic Cardiovascular Disease: Cholesterol, Sterol Regulatory Element-Binding Protein, Inflammation, and Vascular Cell Mobilization in Vasculopathy

Hypercholesterolemia is a well-established risk factor for atherosclerotic cardiovascular disease (ASCVD). How cholesterol and its carrier lipoproteins are involved in ASCVD is still under extensive investigation. Satins are thus far the best-proven class of cholesterol-lowering medications to improve the clinical outcomes of ASCVD. Statins specifically inhibit the rate-limiting enzyme 3-hydroxy-3-methylglutaryl-CoA reductase of the mevalonate pathway for cholesterol biosynthesis. The widely accepted theory is that statins inhibit the hepatic cholesterol synthesis causing upregulation of hepatocyte low-density lipoprotein (LDL) receptor; receptor-mediated LDL uptake and metabolism in the liver results in reduction of circulating LDL cholesterol, which subsequently reduces vascular deposition and retention of cholesterol or LDL in atherogenesis. Nevertheless, cholesterol biosynthesis is ubiquitous, also in extrahepatic cells including those in vascular wall, under tight regulation by sterol regulatory element-binding protein (SREBP), the master gene transcription factor governing cholesterol biosynthesis. Studies have shown that SREBP can be upregulated in vascular wall subject to injury or stent implantation. SREBP can be activated by proinflammatory and mitogenic factors in vascular cells, leading to hyperactive mevalonate pathway, which promotes vascular cell mobilization, further proinflammatory and mitogenic factor release from vascular cells, and vascular inflammation. In this article, we review the cellular cholesterol homeostasis regulation by SREBP and SREBP-mediated vascular hyperactive cholesterol biosynthesis, we term vascular hypercholesterolism, in the pathogenesis of ASCVD and vasculopathy. SREBP functions as a platform bridging cholesterol, inflammation, and vascular cell mobilization in ASCVD pathogenesis. Targeting vascular hypercholesterolism could open a new avenue in fighting against ASCVD.

Targeting Pancreatic Islet NLRP3 Improves Islet Graft Revascularization

Hypoxia-induced islet cell death, caused by an insufficient revascularization of the grafts, is a major obstacle for successful pancreatic islet transplantation. Recently, it has been reported that the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is expressed in pancreatic islets and that its loss protects against hypoxia-induced cell death. Therefore, we hypothesized that the inhibition of NLRP3 in islets improves the survival and endocrine function of the grafts. The transplantation of Nlrp3-/- islets or wild-type (WT) islets exposed to the NLRP3 inhibitor CY-09 into mouse dorsal skinfold chambers resulted in an improved revascularization compared with controls. An increased insulin release after NLRP3 inhibition caused the enhanced angiogenic response. Moreover, the inhibition of NLRP3 in hypoxic β-cells triggered insulin gene expression by inducing the shuttling of MafA and pancreatic and duodenal homeobox-1 into the nucleus. This was mediated by a reduced interaction of NLRP3 with the thioredoxin-interacting protein (TXNIP). Transplantation of Nlrp3-/- islets or WT islets exposed to CY-09 under the kidney capsule of diabetic mice markedly improved the restoration of normoglycemia. These findings indicate that the inhibition of NLRP3 in isolated islets represents a promising therapeutic strategy to improve engraftment and function of the islets.

Identification and characterization of stem cell secretome-based recombinant proteins for wound healing applications

Stem cells have been introduced as a promising therapy for acute and chronic wounds, including burn injuries. The effects of stem cell-based wound therapies are believed to result from the secreted bioactive molecules produced by stem cells. Therefore, treatments using stem cell-derived conditioned medium (CM) (referred to as secretome) have been proposed as an alternative option for wound care. However, safety and regulatory concerns exist due to the uncharacterized biochemical content and variability across different batches of CM samples. This study presents an alternative treatment strategy to mitigate these concerns by using fully characterized recombinant proteins identified by the CM analysis to promote pro-regenerative healing. This study analyzed the secretome profile generated from human placental stem cell (hPSC) cultures and identified nine predominantly expressed proteins (ANG-1, FGF-7, Follistatin, HGF, IL-6, Insulin, TGFβ-1, uPAR, and VEGF) that are known to contribute to wound healing and angiogenesis. These proteins, referred to as s (CMFs), were used in combination to test the effects on human dermal fibroblasts (HDFs). Our results showed that CMF treatment increased the HDF growth and accelerated cell migration and wound closure, similar to stem cell and CM treatments. In addition, the CMF treatment promoted angiogenesis by enhancing new vessel formation. These findings suggest that the defined CMF identified by the CM proteomic analysis could be an effective therapeutic solution for wound healing applications. Our strategy eliminates the regulatory concerns present with stem cell-derived secretomes and could be developed as an off-the-shelf product for immediate wound care and accelerating healing.

EPDR1 is a noncanonical effector of insulin-mediated angiogenesis regulated by an endothelial-specific TGF-β receptor complex

Insulin signaling in blood vessels primarily functions to stimulate angiogenesis and maintain vascular homeostasis through the canonical PI3K and MAPK signaling pathways. However, angiogenesis is a complex process coordinated by multiple other signaling events. Here, we report a distinct crosstalk between the insulin receptor and endoglin/activin receptor-like kinase 1 (ALK1), an endothelial cell-specific TGF-β receptor complex essential for angiogenesis. While the endoglin-ALK1 complex normally binds to TGF-β or bone morphogenetic protein 9 (BMP9) to promote gene regulation via transcription factors Smad1/5, we show that insulin drives insulin receptor oligomerization with endoglin-ALK1 at the cell surface to trigger rapid Smad1/5 activation. Through quantitative proteomic analysis, we identify ependymin-related protein 1 (EPDR1) as a major Smad1/5 gene target induced by insulin but not by TGF-β or BMP9. We found endothelial EPDR1 expression is minimal at the basal state but is markedly enhanced upon prolonged insulin treatment to promote cell migration and formation of capillary tubules. Conversely, we demonstrate EPDR1 depletion strongly abrogates these angiogenic effects, indicating that EPDR1 is a crucial mediator of insulin-induced angiogenesis. Taken together, these results suggest important therapeutic implications for EPDR1 and the TGF-β pathways in pathologic angiogenesis during hyperinsulinemia and insulin resistance.

The effect of insulin on response to intravitreal anti-VEGF injection in diabetic macular edema in type 2 diabetes mellitus

Objectives

To assess whether insulin therapy impacts the effectiveness of anti-vascular endothelial growth factor (anti-VEGF) injection for the treatment of diabetic macular edema (DME) in type 2 diabetes mellitus.

Methods

This was a retrospective multi-center analysis. The best-corrected visual acuity (BCVA) at 12 months, BCVA change, central macular thickness (CMT), CMT change, and cumulative injection number were compared between the insulin and the oral hypoglycemic agent (OHA) groups.

Results

The mean final BCVA and CMT improved in both the insulin (N = 137; p < 0.001; p < 0.001, respectively) and the OHA group (N = 61; p = 0.199; p < 0.001, respectively). The two treatment groups were comparable for final BCVA (p = 0.263), BCVA change (p = 0.184), final CMT (p = 0.741), CMT change (p = 0.458), and the cumulative injections received (p = 0.594). The results were comparable between the two groups when stratified by baseline vision (p > 0.05) and baseline HbA1c (p > 0.05).

Conclusion

Insulin therapy does not alter treatment outcomes for anti-VEGF therapy in DME.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02325-x.

Insulin Topical Application for Wound Healing in Nondiabetic Patients

BACKGROUND

Low-cost and safe strategies to improve wound healing will be of great social and economic value. The goal of this pilot clinical trial is aimed at analyzing how effective insulin therapy is at healing wounds in nondiabetic people.

METHODS

In this protocol research, 346 individuals were included. Patients were divided as 2 groups at random: experimental patients were given a ten-unit answer. For each 10 cm2 of wound, insulin was injected in solution with 1 mL 0.9 percent saline, whereas the control group got a standard dressing with normal saline.

RESULTS

During the therapy period, no adverse effects were reported. After insulin therapy, no substantial insulin-related side effects were reduced. After 10 days of therapy, the experimental group's granulation tissue coverage rate and thickness were considerably improved as compared to control. Furthermore, a momentous difference in the occurrence of wound bleeding and suppurative wounds between the two groups (P = 0.05).

CONCLUSION

The results of this pilot research suggest that insulin injections could harmless and effective alternative therapy for wound healing in nondiabetic individuals and that larger, placebo-controlled trials are needed to evaluate effectiveness and safety of insulin treatment in wound healing patients.

Endothelial Insulin Receptors Promote VEGF-A Signaling via ERK1/2 and Sprouting Angiogenesis

Endothelial insulin receptors (Insr) promote sprouting angiogenesis, although the underpinning cellular and molecular mechanisms are unknown. Comparing mice with whole-body insulin receptor haploinsufficiency (Insr+/-) against littermate controls, we found impaired limb perfusion and muscle capillary density after inducing hind-limb ischemia; this was in spite of increased expression of the proangiogenic growth factor Vegfa. Insr+/- neonatal retinas exhibited reduced tip cell number and branching complexity during developmental angiogenesis, which was also found in separate studies of mice with endothelium-restricted Insr haploinsufficiency. Functional responses to vascular endothelial growth factor A (VEGF-A), including in vitro angiogenesis, were also impaired in aortic rings and pulmonary endothelial cells from Insr+/- mice. Human umbilical vein endothelial cells with shRNA-mediated knockdown of Insr also demonstrated impaired functional angiogenic responses to VEGF-A. VEGF-A signaling to Akt and endothelial nitric oxide synthase was intact, but downstream signaling to extracellular signal-reduced kinase 1/2 (ERK1/2) was impaired, as was VEGF receptor-2 (VEGFR-2) internalization, which is required specifically for signaling to ERK1/2. Hence, endothelial insulin receptors facilitate the functional response to VEGF-A during angiogenic sprouting and are required for appropriate signal transduction from VEGFR-2 to ERK1/2.

Regenerative Effects of Hypoxia Primed Flowable Placental Formulation in Muscle and Dermal Injury

The placental tissue, due to its angiogenic, anti-inflammatory, antioxidative, antimicrobial, and anti-fibrotic properties, has become a compelling source towards a solution for several indications in regenerative medicine. However, methods to enhance and capture the therapeutic properties with formulations that can further the applications of viable placental tissue have not been explored. In this study, we investigated the regenerative effects of a hypoxia primed flowable placental formulation (FPF), composed of amnion/chorion and umbilical tissue, in two in vivo injury models. Laser Doppler data from rodent ischemia hindlimbs treated with FPF revealed significant tissue perfusion improvements compared to control ischemic hindlimbs. To further corroborate FPF's effects, we used a rodent ischemic bipedicle skin flap wound model. FPF treatment significantly increased the rate of wound closure and the quality of wound healing. FPF-treated wounds displayed reduced inflammation and an increase in angiogenesis. Furthermore, quantitative PCR and next-generation sequencing analysis confirmed these changes in the FPF-treated group at both the gene and transcriptional level. The observed modulation in miRNAs was associated with angiogenesis, regulation of inflammatory microenvironment, cell migration and apoptosis, reactive oxygen species generation, and restoring epithelial barrier function, all processes involved in impaired tissue healing. Taken together, these data validate the tissue regenerative properties of the flowable placental formulation configuration tested.

Improvement of islet transplantation by the fusion of islet cells with functional blood vessels

Pancreatic islet transplantation still represents a promising therapeutic strategy for curative treatment of type 1 diabetes mellitus. However, a limited number of organ donors and insufficient vascularization with islet engraftment failure restrict the successful transfer of this approach into clinical practice. To overcome these problems, we herein introduce a novel strategy for the generation of prevascularized islet organoids by the fusion of pancreatic islet cells with functional native microvessels. These insulin-secreting organoids exhibit a significantly higher angiogenic activity compared to freshly isolated islets, cultured islets, and non-prevascularized islet organoids. This is caused by paracrine signaling between the β-cells and the microvessels, mediated by insulin binding to its corresponding receptor on endothelial cells. In vivo, the prevascularized islet organoids are rapidly blood-perfused after transplantation by the interconnection of their autochthonous microvasculature with surrounding blood vessels. As a consequence, a lower number of islet grafts are required to restore normoglycemia in diabetic mice. Thus, prevascularized islet organoids may be used to improve the success rates of clinical islet transplantation.

[Expression of tumor-associated vascular insulin receptor in colorectal cancer and its relationship with tumor pathological features]

OBJECTIVE

To study the expression of tumor associated vascular insulin receptor (TVIR) in colorectal cancer with or without metabolic syndrome (MS) and its relationship with the pathological features of colorectal cancer.

METHODS

The expression of TVIR in 220 colorectal cancer specimens was detected by tissue microarray and immunohistochemistry. The relationships between the expression of TVIR and the pathological features (pathological subtypes, histological grade, invasion depth, lymph node metastasis and TNM stage) of colorectal cancer with/without MS were analyzed.

RESULTS

The insulin receptor expression was observed in colorectal cancer tissue or border area between cancer and normal tissue, but not in normal intestinal tissue. The high-expression rates of TVIR in MS group was remarkably lower than that of non-MS group (21.6%vs. 41.0%, P< 0.05). TVIR high expression was significantly associated with tumor deep invasion, lymph node metastasis and high TNM stage (P<0.05 or P<0.01). Univariate logistic regression analysis showed high-expression of TVIR to be significantly associated with risk of deep invasion (OR=2.21, 95% CI: 1.10-4.44, P<0.05), lymph node metastasis (OR=2.21, 95% CI: 1.26-3.86, P<0.01) and high TNM stage (OR=2.08, 95% CI: 1.19-3.63, P<0.05). Such associations can be observed in patients without MS, but not in patients with MS.

CONCLUSIONS

s: High-expression of TVIR is associated with aggressive pathological features such as invasion, lymph node metastasis and high TNM stage of colorectal cancer, especially for those patients without MS. TVIR could be a useful biological marker for prognosis of colorectal cancer.

Insulin-Containing Wound Dressing Promotes Diabetic Wound Healing Through Stabilizing HIF-1α

HIF-1α is seen as a major regulator during wound healing and controls many wound healing processes, such as angiogenesis, extracellular deposition, and reepithelialization. A diabetic state plays a vicious effect on wound healing, and the destabilization of HIF-1α is a non-negligible factor. Insulin-loaded silk fibroin microparticles were prepared to release insulin by covering the wounds, and this material was proven to promote wound healing in both in vitro and in vivo studies. In this work, we found that this insulin-containing wound dressing could accelerate diabetic wound healing by promoting reepithelialization, angiogenesis, and extracellular matrix, especially collagen deposition. Meanwhile, HIF-1α was stable and accumulated in insulin-containing dressing to group wound cells, which was significantly unstable in the control group. In further studies, we showed that methylglyoxal (MGO), the main form of advanced glycation end products (AGEs), accumulated significantly and caused the destabilization of HIF-1α in the diabetic state. Insulin could alleviate the MGO-induced HIF-1α unstable state and promote HIF-1α target gene expression and its downstream biological effect such as angiogenesis and wound extracellular matrix deposition.

The efficacy of topical insulin application on rat model with burn wounds treated with adipose-derived stem cells

Overall, major burn wounds may require special care and long-term hospitalization as they not only bring complications from the wound itself, but may also compromise the immune system, or even other organs. Previous studies have indicated that topical insulin cream shortened wound closure time in second-degree burns in rats. Transplanted adipose-derived stem cells (AD-MSCs) have been developed as an alternative to treat burns and to accelerate the healing process. The aim of the present study is to investigate the effect of topical insulin gel, associated with AD-MSCs intradermal administration to heal second-degree burn wounds in rat models who were subjected to second-degree dorsal burns. The models were divided into four groups (n = 10 per group): placebo gel (C), topical insulin gel (TI), topical insulin gel and adipose-derived mesenchymal stem cells (TIMSCs) and placebo gel and adipose-derived mesenchymal stem cells (CMSCs). Wounds were assessed on a daily basis and histological evaluations were made on 5 animals from each group on the seventh and fourteenth day. There was a significant macroscopic decrease in burn wound areas in the Control (P = 0.0083), TIMSCs and CMSCs (P = 0.042) groups between the seventh and fourteenth days. The TI treatment did not show any significant change (P > 0.05) throughout this same period. The histological analysis showed significant granulation tissue formation in CMSCs and TIMSCs (P = 0.02235) treatments during the experimental period. According to the results, intradermal administration of allogenic AD-MSCs in experimental second-degree burns for short periods of time in the rat model has contributed to reducing the inflammatory phase duration, improving wound re-epithelialization, tissue granulation and wound contraction, as well as increasing collagen deposition.

Dual Functionalized Injectable Hybrid Extracellular Matrix Hydrogel for Burn Wounds

Low strength and rapid biodegradability of acellular dermal matrix (ADM) restrict its wider clinical application as a rapid cell delivery platform in situ for management of burn wounds. Herein, the extracted ADM was modified by a dual cross-linking approach with ionic crosslinking using chitosan and covalent cross-linking using an iodine-modified 2,5-dihydro-2,5-dimethoxy-furan cross-linker, termed as CsADM-Cl. In addition, inherent growth factors and cytokines were found to be preserved in CsADM-Cl, irrespective of ionic/covalent crosslinking. CsADM-Cl demonstrated improvement in post crosslinking stiffness with a decreased biodegradation rate. This hybrid crosslinked hydrogel supported adhesion, proliferation, and migration of human foreskin-derived fibroblasts and keratinocytes. Also, the angiogenic potential of CsADM-Cl was manifested by chick chorioallantoic membrane assay. CsADM-Cl showed excellent antibacterial activity against Escherichia coli and Staphylococcus aureus. Moreover, CsADM-Cl treated full thickness burn wounds and demonstrated rapid healing marked with superior angiogenesis, well-defined dermal-epidermal junctions, mature basket weave collagen deposition, and development of more pronounced secondary appendages. Altogether, the bioactive CsADM-Cl hydrogel established significant clinical potential to support wound healing as an apt injectable antibacterial matrix to encounter unmet challenges concerning critical burn wounds.

Clinical implications, diagnosis, and management of diabetes in patients with chronic liver diseases

Diabetes mellitus (DM) negatively affects the development and progression of chronic liver diseases (CLD) of various etiologies. Concurrent DM and CLD are also associated with worse clinical outcomes with respect to mortality, the occurrence of hepatic decompensation, and the development of hepatocellular carcinoma (HCC). Unfortunately, early diagnosis and optimal treatment of DM can be challenging, due to the lack of established clinical guidelines as well as the medical complexity of this patient population. We conducted an exploratory review of relevant literature to provide an up-to-date review for internists and hepatologists caring for this patient population. We reviewed the epidemiological and pathophysiological associations between DM and CLD, the impact of insulin resistance on the progression and manifestations of CLD, the pathogenesis of hepatogenic diabetes, as well as the practical challenges in diagnosis and monitoring of DM in this patient population. We also reviewed the latest clinical evidence on various pharmacological antihyperglycemic therapies with an emphasis on liver disease-related clinical outcomes. Finally, we proposed an algorithm for managing DM in patients with CLD and discussed the clinical and research questions that remain to be addressed.

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.

Topical Insulin Modulates Inflammatory and Proliferative Phases of Burn-Wound Healing in Diabetes-Induced Rats

The healing time of burn wounds depends on surface area and depth of the burn and associated comorbidities. Diabetes mellitus (DM) causes delays in the healing process by extending the inflammatory phase. Treatment with topical insulin can improve the inflammatory phase, restore metabolic dysregulation, and modulate impaired cellular signaling in burn wounds. The objective of this study was to evaluate markers of the inflammatory and proliferative phases of second-degree burns after topical insulin treatment in diabetic rats. Type I DM was induced with streptozotocin in male Wistar rats. The animals' backs were shaved and subjected to thermal burning. Rats were randomized into two groups: control diabetic (DC) and insulin diabetic (DI). At Days 7 and 14 postburn, rats were euthanized, and wound-tissue sections were evaluated by hematoxylin and eosin, Weigert, and Verhöeff staining, immunohistochemistry-paraffin, and enzyme-linked immunosorbent assay. A significant increase in reepithelialization was seen on Days 7 and 14 in DI versus DC rats. On Day 7, interleukin (IL)-1β, IL-6, monocyte chemotactic protein (MCP)-1, and F4/80 expression were increased in DI versus DC rats. On Day 14, MCP-1 expression was decreased and F4/80 increased in DI versus DC rats. On Days 7 and 14, Ki-67, transforming growth factor-β1, vascular endothelial growth factor expression, and formation of elastic fibers were increased in DI versus DC rats. Topical insulin modulates burn-wound healing in diabetic animals by balancing inflammation and promoting angiogenesis and formation of elastic fibers.

Advanced 2D/3D cell migration assay for faster evaluation of chemotaxis of slow-moving cells

Considering the essential role of chemotaxis of adherent, slow-moving cells in processes such as tumor metastasis or wound healing, a detailed understanding of the mechanisms and cues that direct migration of cells through tissues is highly desirable. The state-of-the-art chemotaxis instruments (e.g. microfluidic-based devices, bridge assays) can generate well-defined, long-term stable chemical gradients, crucial for quantitative investigation of chemotaxis in slow-moving cells. However, the majority of chemotaxis tools are designed for the purpose of an in-depth, but labor-intensive analysis of migratory behavior of single cells. This is rather inefficient for applications requiring higher experimental throughput, as it is the case of e.g. clinical examinations, chemoattractant screening or studies of the chemotaxis-related signaling pathways based on subcellular perturbations. Here, we present an advanced migration assay for accelerated and facilitated evaluation of the chemotactic response of slow-moving cells. The revised chemotaxis chamber contains a hydrogel microstructure–the migration arena, designed to enable identification of chemotactic behavior of a cell population in respect to the end-point of the experiment. At the same time, the assay in form of a microscopy slide enables direct visualization of the cells in either 2D or 3D environment, and provides a stable and linear gradient of chemoattractant. We demonstrate the correctness of the assay on the model study of HT-1080 chemotaxis in 3D and on 2D surface. Finally, we apply the migration arena chemotaxis assay to screen for a chemoattractant of primary keratinocytes, cells that play a major role in wound healing, being responsible for skin re-epithelialization and a successful wound closure. In direction of new therapeutic strategies to promote wound repair, we identified the chemotactic activity of the epithelial growth factor receptor (EGFR) ligands EGF and TGFα (transforming growth factor α).

Differential microRNA expression between decidual and peripheral blood natural killer cells in early pregnancy

STUDY QUESTION

Have decidual natural killer (dNK) cells a different microRNA (miRNA or miR) expression pattern compared to NK cells circulating in the peripheral blood (pb) of healthy pregnant women in the first trimester of gestation?

SUMMARY ANSWER

dNK cells have a unique miRNA profile, showing exclusive expression of a set of miRNAs and significant up- or down-regulation of most of the miRNAs shared with pbNK cells.

WHAT IS KNOWN ALREADY

dNK cells differ from pbNK cells both phenotypically and functionally, and their origin is still debated. Many studies have indicated that miRNAs regulate several important aspects of NK cell biology, such as development, activation and effector functions.

STUDY DESIGN, SIZE, DURATION

Decidua basalis and peripheral blood specimens were collected from women (n = 7) undergoing voluntary termination of gestation in the first trimester of pregnancy. dNK and pbNK cells were then highly purified by cell sorting.

PARTICIPANTS/MATERIALS, SETTING, METHODS

miRNAs expression was analysed by quantitative RT-PCR (qRT-PCR)-based arrays using RNA purified from freshly isolated and highly purified pbNK and dNK cells. Results from arrays were validated by qRT-PCR assays. The bioinformatics tool ingenuity pathway analysis (IPA) was applied to determine the cellular network targeted by validated miRNAs and the correlated biological functions.

MAIN RESULTS AND THE ROLE OF CHANCE

Herein, we identified the most differentially expressed miRNAs in NK cells isolated from peripheral blood and uterine decidua of pregnant women. We found that 36 miRNAs were expressed only in dNK cells and two miRNAs only in pbNK cells. Moreover, 48 miRNAs were commonly expressed by both NK cell preparations although at different levels: 28 were upregulated in dNK cells, while 15 were downregulated compared to pbNK cells. Validation of a selected set (n = 11) of these miRNAs confirmed the differential expression of nine miRNAs: miR-10b and miR-214 expressed only in dNK cells and miR-200a-3p expressed only in pbNK cells; miR-130b-3p, miR-125a-5p, miR-212-3p and miR-454 were upregulated while miR-210-3p and miR-132 were downregulated in dNK cells compared to pbNK cells. IPA network analysis identified a single network connecting all the miRNAs as well as their significant involvement in several classes of functions: 'Organismal injury, Reproductive system disease, Inflammatory disease' and 'Cellular development'. These miRNAs target molecules such as argonaute 2, tumour protein p53, insulin and other genes that belong to the same network and significantly influence cell differentiation and pregnancy.

LIMITATIONS, REASONS FOR CAUTION

In the present study, the cellular network and biological functions modulated by miRNAs differentially expressed in dNK and pbNK cells were identified by IPA considering only molecules and relationships that were with confidence 'experimentally observed' in leucocytes. The decidual and pbNK cells that were analysed here are a heterogeneous population and further study will help to disentangle whether there are differences in miRNA production by the different subsets of NK cells.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study describing a different miRNA expression profile in dNK cells compared to matched pbNK cells during the first trimester of pregnancy. Our findings improved the body of knowledge on dNK cell biology and strongly suggest further investigation into the roles of miRNAs that are differentially expressed in human dNK compared to pbNK cells. Our results suggest that specific miRNAs can modulate dNK cell origin and functions, highlighting a potential role of this miRNA signature in human development and diseases.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from the Istituto Pasteur, Fondazione Cenci Bolognetti, the European NoE EMBIC within FP6 (Contract number LSHN-CT-2004-512040), Istituto Italiano di Tecnologia, and Ministero dell'Istruzione, dell'Università e della Ricerca (Ricerche Universitarie), and from Università Politecnica delle Marche. There are no conflicts of interest to declare.

Therapeutic strategies for enhancing angiogenesis in wound healing

The enhancement of wound healing has been a goal of medical practitioners for thousands of years. The development of chronic, non-healing wounds is a persistent medical problem that drives patient morbidity and increases healthcare costs. A key aspect of many non-healing wounds is the reduced presence of vessel growth through the process of angiogenesis. This review surveys the creation of new treatments for healing cutaneous wounds through therapeutic angiogenesis. In particular, we discuss the challenges and advancement that have been made in delivering biologic, pharmaceutical and cell-based therapies as enhancers of wound vascularity and healing.

Insulin Mucoadhesive Liposomal Gel for Wound Healing: a Formulation with Sustained Release and Extended Stability Using Quality by Design Approach

The present study deals with the formulation of topical insulin for wound healing with extended stability and sustained release, by applying quality by design concepts. Insulin has been promoted as a promising therapeutic wound healing agent. Topical formulation of insulin faced major problems, as it cannot be delivered safely to the wound with a controlled rate. Formulation of insulin-loaded vesicles in optimized bio-adhesive hydrogels has been explored to ensure a safe delivery of insulin to wounds in a controlled manner. Quality by design (QbD) was applied to study the effect of several critical process parameters on the critical quality attributes. Ishikawa diagram was used to identify the highest risk factors, which were screened by a fractional factorial design and augmented by Box-Behnken design. The optimized formula was incorporated into a mucoadhesive gel, which was further subjected to stability and clinical studies. An optimized formula was obtained with a particle size of 257.751 nm, zeta potential - 20.548 mv, 87.379% entrapment efficiency, and a release rate of 91.521 μg/cm²/h. The results showed that liposomal insulin remained stable for 6 months in aqueous dispersion state at 4°C. Moreover, the release was sustained up to 24 h. The clinical study showed an improvement in the wound healing rate, 16 times, as the control group, with magnificent reduction in the erythema of the ulcer and no signs of hypoglycemia. Insulin-loaded liposomal chitosan gel showed a promising drug delivery system with high stability and sustained release.

BZ043, a novel long-acting amylin analog, reduces gastric emptying, food intake, glycemia and insulin requirement in streptozotocin-induced diabetic rats

Amylin analogs are important adjunctive drugs in the treatment of diabetes mellitus. However, a dual therapy with insulin involves inconvenient multiple injections. Here we describe a novel n-terminal PEGylated human amylin analog - BZ043 - and its potential to improve the control of glycemia using lower doses of insulin. The effect of BZ043 over the insulin-mediated control of fed-glycemia was investigated in rats with streptozotocin-induced diabetes treated with the basal analog glargine (GLAR). Fasted rats (3 h) received a single treatment of BZ043 (16, 64 or 128 nmol/kg), GLAR (1.5 IU or 6.0 IU) or BZ043 plus GLAR low dose (1.5 IU) in separate injections, and had free access to 5% glucose rich chow and water. BZ043 dose-proportionally prevented the meal-related increase of glycemia, and the co-treatment (64 or 128 nmol/kg) with GLAR restored normoglycemia without abrupt variations of glycemia. BZ043 showed a prolonged anti-hyperglycemic effect and, together with GLAR, promoted a long-lasting normoglycemia, in vivo. We conceive that combining BZ043 and GLAR in a fixed-ratio co-formulation might conveniently improve the control of diabetes mellitus.

Insulin and Insulin Receptors in Adipose Tissue Development

Insulin is a major endocrine hormone also involved in the regulation of energy and lipid metabolism via the activation of an intracellular signaling cascade involving the insulin receptor (INSR), insulin receptor substrate (IRS) proteins, phosphoinositol 3-kinase (PI3K) and protein kinase B (AKT). Specifically, insulin regulates several aspects of the development and function of adipose tissue and stimulates the differentiation program of adipose cells. Insulin can activate its responses in adipose tissue through two INSR splicing variants: INSR-A, which is predominantly expressed in mesenchymal and less-differentiated cells and mainly linked to cell proliferation, and INSR-B, which is more expressed in terminally differentiated cells and coupled to metabolic effects. Recent findings have revealed that different distributions of INSR and an altered INSR-A:INSR-B ratio may contribute to metabolic abnormalities during the onset of insulin resistance and the progression to type 2 diabetes. In this review, we discuss the role of insulin and the INSR in the development and endocrine activity of adipose tissue and the pharmacological implications for the management of obesity and type 2 diabetes.

Enhanced TGF-β Signaling Contributes to the Insulin-Induced Angiogenic Responses of Endothelial Cells

Angiogenesis, the development of new blood vessels, is a key process in disease. We reported that insulin promotes translocation of transforming growth factor β (TGF-β) receptors to the plasma membrane of epithelial and fibroblast cells, thus enhancing TGF-β responsiveness. Since insulin promotes angiogenesis, we addressed whether increased autocrine TGF-β signaling participates in endothelial cell responses to insulin. We show that insulin enhances TGF-β responsiveness and autocrine TGF-β signaling in primary human endothelial cells, by inducing a rapid increase in cell surface TGF-β receptor levels. Autocrine TGF-β/Smad signaling contributed substantially to insulin-induced gene expression associated with angiogenesis, including TGF-β target genes encoding angiogenic mediators; was essential for endothelial cell migration; and participated in endothelial cell invasion and network formation. Blocking TGF-β signaling impaired insulin-induced microvessel outgrowth from neonatal aortic rings and modified insulin-stimulated blood vessel formation in zebrafish. We conclude that enhanced autocrine TGF-β signaling is integral to endothelial cell and angiogenic responses to insulin.

The expression of the insulin receptor in gastric cancer correlates with the HER2 status and may have putative therapeutic implications

BACKGROUND

Metabolic reprogramming in gastric cancer (GC) involves not only an alteration of glucose metabolism, but also of insulin receptor (IR) expression. We investigated if (1) GCs express the IR in cancer cells (CC-IR) and vasculature (VIR), (2) IR expression is clinically relevant and may be a novel target of GC treatment.

METHODS

467 primary GCs were studied by immunohistochemistry using an IR-specific antibody. CD31-immunostaining ensured the presence of representative intratumoral microvasculature. VIR, and membranous and cytoplasmic CC-IR (mCC-IR, cCC-IR) were evaluated using a modified HistoScore (HScore) and subsequently dichotomized into low or high IR expressions. The IR status was correlated with clinico-pathological patient characteristics, including survival and HER2 status.

RESULTS

VIR, mCC-IR, and cCC-IR (HScore > 0) were found in 97.0%, 87.6%, and 95.7% of all GCs. After dichotomization of the HScores, 50.7, 48.8, and 50.3% were classified as VIR-high, mCC-IR-high, and cCC-IR-high, respectively. IR was associated with the Laurén phenotype, tumor localization, local tumor growth, vascular invasion, perineural invasion, tumor budding, mucin phenotype, UICC stage, worse survival, and the HER2 status. On multivariate analysis, VIR status was an independent prognosticator of overall (p = 0.010) and tumor-specific (p = 0.006) patient survival.

CONCLUSIONS

VIR and CC-IR expressions are frequent in GC, biologically significant and even correlate with the HER2 status, opening avenues for novel putative therapeutic interventions in GC.

Epithelial insulin receptor expression-prognostic relevance in colorectal cancer

Background

Metabolic reprogramming in cancer encompasses the insulin receptor (IR) as a player of energy homeostasis and proliferation. We aimed to characterize vascular (VIR) and epithelial (EIR) IR expression in CRC and correlate it with clinico-pathological parameters and survival.

Methods

1580 primary CRCs were explored by immunohistochemistry for evaluation of VIR and EIR. Subgroup analyses included in situ hybridization for IR isoform A (IR-A) and DNA mismatch repair protein immunohistochemistry. Clinico-pathological and survival parameters were studied.

Results

High VIR was evident in 63.5% of all CRC samples and was associated with T-stage (P = 0.005). EIR was present in 72.2% and was associated with lower T-stages (P = 0.006) and UICC-stages (P < 0.001). EIR negativity was associated with increased metastasis (P = 0.028), nodal spread (P < 0.001), lymphatic invasion (P = 0.008) and a decreased tumor-specific (P = 0.011) and overall survival (P = 0.007; 95%-C.I.: 44.5-84.1). EIR negativity in UICC-stage II was associated with a significantly worse tumor-specific (P = 0.045) and overall (P = 0.043) survival. IR-A was expressed in CRC vessels and cells.

Conclusions

We demonstrate VIR to be frequent in CRC and characterize EIR negativity as an important prognostic risk factor. The association between EIR negativity and worse survival in UICC-stage II should be prospectively evaluated for an application in therapeutic algorithms.

Oncofoetal insulin receptor isoform A marks the tumour endothelium; an underestimated pathway during tumour angiogenesis and angiostatic treatment

Background

In a genomic screen for determinants of the tumour vasculature, we identified insulin receptor (INSR) to mark the tumour endothelium. As a functional role for insulin/INSR in cancer has been suggested and markers of the tumour endothelium may be attractive therapeutic targets, we investigated the role of INSR in angiogenesis.

Methods

In a genomic screen for determinants of the tumour vasculature we identified insulin receptor to mark the tumour endothelium.

Results

The current report demonstrates the following: (i) the heavy overexpression of INSR on angiogenic vasculature in human tumours and the correlation to short survival, (ii) that INSR expression in the tumour vasculature is mainly representing the short oncofoetal and non-metabolic isoform INSR-A, (iii) the angiogenic activity of insulin on endothelial cells (EC) in vitro and in vivo, (iv) suppression of proliferation and sprouting of EC in vitro after antibody targeting or siRNA knockdown, and (v) inhibition of in vivo angiogenesis in the chicken chorioallantoic membrane (CAM) by anti-INSR antibodies. We additionally show, using preclinical mouse as well as patient data, that treatment with the inhibitor sunitinib significantly reduces the expression of INSR-A.

Conclusions

The current study underscores the oncogenic impact of INSR and suggests that targeting the INSR-A isoform should be considered in therapeutic settings.

Insulin reverses major portal hypertension-related derangements in rats with liver cirrhosis and diabetes

Liver cirrhosis is accompanied by increased intrahepatic resistance and angiogenesis-related portosystemic collaterals formation. Diabetic patients suffer from abnormal vasoresponsiveness and angiogenesis that can be ameliorated by glucose control. However, the relevant presentation is not clear in those with cirrhosis and diabetes, in whom insulin is the treatment of choice. Liver cirrhosis was induced in Sprague–Dawley rats with common bile duct ligation (BDL) and sham rats were used as controls. Streptozotocin 60 mg/kg (STZ, i.p., to induce diabetes) or vehicle was injected. The rats received BDL and STZ injections were injected with insulin or vehicle. On the 29th day after the procedure, the groups were surveyed for (1) systemic and portal hemodynamics; (2) mesenteric vascular density; (3) severity of portosystemic collaterals; (4) hepatic resistance using in situ liver perfusion; (5) histology survey of mesentery and liver; and (6) mesentery angiogenesis- and liver fibrogenesis-related protein expressions. Compared with the cirrhotic rats, the cirrhotic diabetic rats had lower body weight, cardiac output, superior mesenteric arterial (SMA) resistance and portal venous (PV) resistance, and higher SMA and PV flow, which were mostly reversed by insulin. The cirrhotic diabetic rats also had increased mesenteric vascular density, and enhanced pERK, pAkt, VEGF, VEGFR2 protein expressions that were reversed by insulin. Insulin decreased the degree of shunting in the diabetic cirrhotic rats. Hepatic perfusion pressure and severity of liver fibrosis were not significantly influenced by diabetes and insulin treatment in the cirrhotic rats. In conclusion, diabetes aggravated hemodynamic derangements, mesenteric angiogenesis and collaterals in the cirrhotic rats, which were mostly ameliorated by insulin. Further clinical investigations are warranted.

Insulin promotes macrophage phenotype transition through PI3K/Akt and PPAR-γ signaling during diabetic wound healing

Overactivation and persistent chronic inflammation are the major pathogenic characteristics of diabetic-impaired healing, and diabetic wound healing can be promoted by stimulating the transition of macrophage phenotype from pro-inflammatory (M1) to anti-inflammatory (M2). Our previous studies found that the application of insulin induced an advanced initiation and resolution of inflammatory response. To further explore the mechanism, we have investigated the effect of insulin on macrophage phenotype switch utilizing a diabetic rat model and a human monocytic THP-1 cell. We have utilized the high glucose (HG) and HG plus insulin to stimulate the M1 macrophages derived from lipopolysaccharide-treated THP-1 cells. We studied the secretion of inflammatory mediator and related signaling pathways by using western blot test, immunofluorescence, and Rac1 pull-down assay. We have found that the production of pro-inflammatory mediators, which thereafter induced macrophage polarization toward M1 phenotype, has been elevated due to consistent HG exposure. HG plus insulin stimulation, on the other hand, promoted anti-inflammatory effects. Experiments performed on diabetic burn wounds indicated that the insulin modulated macrophages transition from M1 to M2 phenotype. We found that PI3K/Akt/Rac-1 and PPAR-γ signaling pathways are involved in the anti-inflammatory effect of insulin. Insulin inhibited HG-induced activation of p38, NF-κB, and STAT1 transcriptional activity by activating Akt-Rac-1 signaling. Moreover, insulin performs anti-inflammatory effects through upregulation of PPAR-γ expression and induced P38-mediated dephosphorylation of PPAR-γ (Ser112). In conclusion, insulin downregulates inflammatory response, regulates M1 macrophage transition in response to HG, and thus improves chronic wound healing.

Endothelial Insulin Receptor Restoration Rescues Vascular Function in Male Insulin Receptor Haploinsufficient Mice

Reduced systemic insulin signaling promotes endothelial dysfunction and diminished endogenous vascular repair. We investigated whether restoration of endothelial insulin receptor expression could rescue this phenotype. Insulin receptor knockout (IRKO) mice were crossed with mice expressing a human insulin receptor endothelial cell-specific overexpression (hIRECO) to produce IRKO-hIRECO progeny. No metabolic differences were noted between IRKO and IRKO-hIRECO mice in glucose and insulin tolerance tests. In contrast with control IRKO littermates, IRKO-hIRECO mice exhibited normal blood pressure and aortic vasodilatation in response to acetylcholine, comparable to parameters noted in wild type littermates. These phenotypic changes were associated with increased basal- and insulin-stimulated nitric oxide production. IRKO-hIRECO mice also demonstrated normalized endothelial repair after denuding arterial injury, which was associated with rescued endothelial cell migration in vitro but not with changes in circulating progenitor populations or culture-derived myeloid angiogenic cells. These data show that restoration of endothelial insulin receptor expression alone is sufficient to prevent the vascular dysfunction caused by systemically reduced insulin signaling.

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.

Topical insulin accelerates cutaneous wound healing in insulin-resistant diabetic rats

Insulin signaling defects could lead to insulin resistance in insulin target organs: typically, in the muscler, liver, and adipose tissue. We have observed that insulin accelerated diabetic wound healing in our previous works; to further elucidate the mechanism, we investigated the expression and activation of insulin and insulin-like growth factor (IGF)-1 signaling, compared insulin sensitivity in skin tissue with that in liver tissue, and also observed the regulation of insulin on inflammatory response of wounds during the healing process. We found lower expression of insulin receptor, phos-AKT, IGF-1 in type II diabetic rat skin compared with that in normal rat skin. However, the level of phos-AKT in diabetic rat skin remarkably increased after systemic insulin injection, whereas no significant change of phos-AKT was observed in liver upon insulin stimulation. In insulin-treated wounds, we detected a significant increase in insulin signaling proteins and growth factor, as well as the phosphorylated insulin receptor substrate-1 and AKT. The increased Glut1 protein level and translocation of Glut1 from cytosol to cell membrane of the basal epidermal cells were also observed after insulin application. Insulin-treated wounds showed advanced infiltration and resolution of macrophages and a change pattern similar to that of inflammatory mediators, including TNF-α and IL-6. Our findings support that insulin is a valid agent for diabetic wound healing because of its effect on ameliorating defective insulin action and regulating inflammation response. Our results indicate the presence of subtle insulin responsiveness in diabetic skin tissue, regardless of the presence of impaired insulin sensitivity, which could be the cellular and molecular mechanism of insulin accelerating diabetic wound healing.

Insulin Receptor Isoforms in Physiology and Disease: An Updated View

The insulin receptor (IR) gene undergoes differential splicing that generates two IR isoforms, IR-A and IR-B. The physiological roles of IR isoforms are incompletely understood and appear to be determined by their different binding affinities for insulin-like growth factors (IGFs), particularly for IGF-2. Predominant roles of IR-A in prenatal growth and development and of IR-B in metabolic regulation are well established. However, emerging evidence indicates that the differential expression of IR isoforms may also help explain the diversification of insulin and IGF signaling and actions in various organs and tissues by involving not only different ligand-binding affinities but also different membrane partitioning and trafficking and possibly different abilities to interact with a variety of molecular partners. Of note, dysregulation of the IR-A/IR-B ratio is associated with insulin resistance, aging, and increased proliferative activity of normal and neoplastic tissues and appears to sustain detrimental effects. This review discusses novel information that has generated remarkable progress in our understanding of the physiology of IR isoforms and their role in disease. We also focus on novel IR ligands and modulators that should now be considered as an important strategy for better and safer treatment of diabetes and cancer and possibly other IR-related diseases.

Nox2 contributes to hyperinsulinemia-induced redox imbalance and impaired vascular function

Insulin resistance promotes vascular endothelial dysfunction and subsequent development of cardiovascular disease. Previously we found that skeletal muscle arteriolar flow-induced dilation (FID) was reduced following a hyperinsulinemic clamp in healthy adults. Therefore, we hypothesized that hyperinsulinemia, a hallmark of insulin resistance, contributes to microvascular endothelial cell dysfunction via inducing oxidative stress that is mediated by NADPH oxidase (Nox) system. We examined the effect of insulin, at levels that are comparable with human hyperinsulinemia on 1) FID of isolated arterioles from human skeletal muscle tissue in the presence and absence of Nox inhibitors and 2) human adipose microvascular endothelial cell (HAMECs) expression of nitric oxide (NO), endothelial NO synthase (eNOS), and Nox-mediated oxidative stress. In six lean healthy participants (mean age 25.5±1.6 y, BMI 21.8±0.9), reactive oxygen species (ROS) were increased while NO and arteriolar FID were reduced following 60 min of ex vivo insulin incubation. These changes were reversed after co-incubation with the Nox isoform 2 (Nox2) inhibitor, VAS2870. In HAMECs, insulin-induced time-dependent increases in Nox2 expression and P47^phox phosphorylation were echoed by elevations of superoxide production. In contrast, phosphorylation of eNOS and expression of superoxide dismutase (SOD2 and SOD3) isoforms showed a biphasic response with an increased expression at earlier time points followed by a steep reduction phase. Insulin induced eNOS uncoupling that was synchronized with a drop of NO and a surge of ROS production. These effects were reversed by Tempol (SOD mimetic), Tetrahydrobiopterin (BH4; eNOS cofactor), and VAS2870. Finally, insulin induced nitrotyrosine formation which was reversed by inhibiting NO or superoxide generation. In conclusions, hyperinsulinemia may reduce FID via inducing Nox2-mediated superoxide production in microvascular endothelial cells which reduce the availability of NO and enhances peroxynitrite formation. Therefore, the Nox2 pathway should be considered as a target for the prevention of oxidative stress-associated endothelial dysfunction during hyperinsulinemia.

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Hyperinsulinemia impairs FID and induces ROS production in human muscle arterioles.

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Insulin-induced ROS production in endotelial cells is mediated by NADPH oxidase.

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Long exposure to high insulin levels reduces eNOS phosphorylation and NO production.

Pro-angiogenic Role of Insulin: From Physiology to Pathology

The underlying molecular mechanisms involve in the regulation of the angiogenic process by insulin are not well understood. In this review article, we aim to describe the role of insulin and insulin receptor activation on the control of angiogenesis and how these mechanisms can be deregulated in human diseases. Functional expression of insulin receptors and their signaling pathways has been described on endothelial cells and pericytes, both of the main cells involved in vessel formation and maturation. Consequently, insulin has been shown to regulate endothelial cell migration, proliferation, and in vitro tubular structure formation through binding to its receptors and activation of intracellular phosphorylation cascades. Furthermore, insulin-mediated pro-angiogenic state is potentiated by generation of vascular growth factors, such as the vascular endothelial growth factor, produced by endothelial cells. Additionally, diseases such as insulin resistance, obesity, diabetes, and cancer may be associated with the deregulation of insulin-mediated angiogenesis. Despite this knowledge, the underlying molecular mechanisms need to be elucidated in order to provide new insights into the role of insulin on angiogenesis.

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.