Liver is a primary source of insulin-like growth factor-1 in skin wound healing

The modified albumin-bilirubin (ALBI) grade reflect the fate of limb prognosis in patients with chronic limb threatening ischemia

OBJECTIVE

To examine the influence of liver function on patients with chronic limb-threatening ischemia (CLTI), we classified patients with CLTI after revascularization according to their modified ALBI grades.

METHODS

We retrospectively analyzed single-center data of patients who underwent revascularization for CLTI between 2015 and 2020. Patients were classified with modified albumin-bilirubin (ALBI) grades 1, 2a, and 2b & 3 according to the ALBI score, which was calculated based on serum albumin and total bilirubin levels. The endpoints were the two-year amputation-free survival (AFS) and one-year wound healing rates.

RESULTS

We included 190 limbs in 148 patients, and 50, 54, and 86 cases were assigned as grade 1, 2a, and 2b & 3, respectively. The two-year AFS rates for the grade 1, 2a, and 2b & 3 groups were 79 ± 6%, 66% ± 7%, and 45 ± 6%, respectively (P < 0.01). One-year cumulative wound healing rates for grade 1, 2a, and 2b & 3 groups were 68 ± 7%, 69% ± 6%, and 48% ± 5%, respectively (P = 0.01). Multivariate Cox proportional hazard analyses identified age (≥75 years), dependent ambulatory status, and modified ALBI grades 2b & 3 compared with grades 1 and 2a as significant independent predictors of AFS. The dependent ambulatory status and WIfI stage 4 were significant negative predictors of wound healing.

CONCLUSIONS

Many patients with CLTI had high modified ALBI grades and impaired liver function classified as modified ALBI grade 2b or 3 is a robust negative predictor of amputation-free survival.

The Combination of Stromal Vascular Fraction Cells and Platelet-Rich Plasma Increases Fibroblast Growth Factor 2 and Insulin-Like Growth Factor 1 in Full-Thickness Burns in Animal Model

The previous study on the injection of SVFs in combination with PRP showed positive effect on the healing of deep dermal burns. We now seek to understand the effect on full thickness burns, as assessed by changes in serum FGF2, IGF1, epithelialization, and fibroblast count. Forty-eight Wistar rats were randomly divided into four groups: (1) rats with full thickness burns given a local injection of combined SVFs and PRP; (2) rats with burns given topical Vaseline; (3) rats with burns given a local injection of placebo; and (4) rats without burns. Primary data were measured according to the time of euthanasia (at the 8th hour, 4th day, 7th day, 14th day or 21st day). One-way ANOVA test followed by post hoc test were used. Epithelialization in rats who received SVFs and PRP was superior on days 7, 14 and 21 when compared to the other groups. The fibroblast count in rats who received SVFs and PRP showed significant difference on days 7 (p=0.022). Significant differences in serum FGF2 were observed on days 4, 7, 14 and 21 (p=0.003, p=0.001, p=0.024, p=0.038, respectively). A significant difference was also observed in serum IGF1 levels on days 7, 14 and 21 (p=0.043, p=0.003, p=0.045, respectively), and the combination of SVFs and PRP showed superior results compared to other groups. Injection of combined SVFs and PRP increases FGF2, IGF1, fibroblast count, and epithelialization.

Pretreatment with platelet-rich plasma protects against ischemia-reperfusion induced flap injury by deactivating the JAK/STAT pathway in mice

BACKGROUND

Ischemia-reperfusion (I/R) injury is a major cause of surgical skin flap compromise and organ dysfunction. Platelet-rich plasma (PRP) is an autologous product rich in growth factors, with tissue regenerative potential. PRP has shown promise in multiple I/R-induced tissue injuries, but its effects on skin flap injury remain unexplored.

METHODS

We evaluated the effects of PRP on I/R-injured skin flaps, optimal timing of PRP administration, and the involved mechanisms.

RESULTS

PRP protected against I/R-induced skin flap injury by improving flap survival, promoting blood perfusion and angiogenesis, suppressing oxidative stress and inflammatory response, and reducing apoptosis, at least partly via deactivating Janus kinase (JAK)-signal transducers and activators of transcription (STAT) signalling pathway. PRP given before ischemia displayed overall advantages over that given before reperfusion or during reperfusion. In addition, PRP pretreatment had a stronger ability to reverse I/R-induced JAK/STAT activation and apoptosis than AG490, a specific inhibitor of JAK/STAT signalling.

CONCLUSIONS

This study firstly demonstrates the protective role of PRP against I/R-injured skin flaps through negative regulation of JAK/STAT activation, with PRP pretreatment showing optimal therapeutic effects.

Assessment of antimicrobial activity and In Vitro wound healing potential of ZnO nanoparticles synthesized with Capparis spinosa extract

Agents that will accelerate wound healing maintain their clinical importance in all aspects. The aim of this study is to determine the antimicrobial activity of zinc oxide nanoparticles (ZnO NPs) ZnO nanoparticles obtained by green synthesis from Capparis spinosa L. extract and their effect on in vitro wound healing. ZnO NPs were synthesized and characterized using Capparis spinosa L. extract. ZnO NPs were tested against nine ATCC-coded pathogen strains to determine antimicrobial activity. The effects of different doses (0.0390625-20 µg/mL) of NPs on cell viability were determined by MTT assay. The effect of ZnO NPs doses (0.0390625 µg/mL, 0.078125 µg/mL, 0.15625 µg/mL, 0.3125 µg/mL, 0.625 µg/mL, 1.25 µg/mL) that increase proliferation and migration on wound healing was investigated in an in vitro wound experiment. Cell culture medium obtained from the in vitro wound assay was used for biochemical analysis, and plate alcohol-fixed cells were used for immunohistochemical staining. It was determined that NPs formed an inhibition zone against the tested Gram-positive bacteria. The ZnO NPs doses determined in the MTT test provided faster wound closure in in-vitro conditions compared to the DMSO group. Biochemical analyses showed that inflammation and oxidative status decreased, while antioxidant levels increased in ZnO NPs groups. Immunohistochemical analyses showed increased expression levels of Bek/FGFR2, IGF, and TGF-β associated with wound healing. The findings reveal the antimicrobial effect of ZnO nanoparticles obtained using Capparis spinosa L. extract in vitro and their potential applications in wound healing.

Liver insulin-like growth factor-1 mediates effects of low-intensity vibration on wound healing in diabetic mice

Chronic wounds in diabetic patients are associated with significant morbidity and mortality; however, few therapies are available to improve healing of diabetic wounds. Our group previously reported that low-intensity vibration (LIV) could improve angiogenesis and wound healing in diabetic mice. The purpose of this study was to begin to elucidate the mechanisms underlying LIV-enhanced healing. We first demonstrate that LIV-enhanced wound healing in db/db mice is associated with increased IGF1 protein levels in liver, blood, and wounds. The increase in insulin-like growth factor (IGF) 1 protein in wounds is associated with increased Igf1 mRNA expression both in liver and wounds, but the increase in protein levels preceded the increase in mRNA expression in wounds. Since our previous study demonstrated that liver was a primary source of IGF1 in skin wounds, we used inducible ablation of IGF1 in the liver of high-fat diet (HFD)-fed mice to determine whether liver IGF1 mediated the effects of LIV on wound healing. We demonstrate that knockdown of IGF1 in liver blunts LIV-induced improvements in wound healing in HFD-fed mice, particularly increased angiogenesis and granulation tissue formation, and inhibits the resolution of inflammation. This and our previous studies indicate that LIV may promote skin wound healing at least in part via crosstalk between the liver and wound. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Role of NK Cells in Skin Wound Healing of Mice

NK cells are best known for their killing of virus-infected cells and tumor cells via release of cytotoxic factors. However, NK cells can also produce growth factors and cytokines, and thus have the potential to influence physiological processes such as wound healing. In this study, we test the hypothesis that NK cells play a physiological role in skin wound healing of C57BL/6J mice. Immunohistochemical and flow cytometry assays showed that NK cells accumulate in excisional skin wounds, peaking on day 5 postinjury. We also found that NK cells proliferate locally in wounds, and blocking IL-15 activity locally reduces NK cell proliferation and accumulation in wounds. Wound NK cells exhibit primarily a mature CD11b+CD27- and NKG2A+NKG2D- phenotype and express LY49I and proinflammatory cytokines such as IFN-γ, Tnf-a, and Il-1β. Systemic depletion of NK cells resulted in enhanced re-epithelization and collagen deposition, suggesting a negative role for these cells in skin wound healing. Depletion of NK cells did not influence accumulation of neutrophils or monocytes/macrophages in wounds but did reduce expression of IFN-γ, Tnf-a, and Il-1β, indicating that NK cells contribute to proinflammatory cytokine expression in wounds. In short, NK cells may impede physiological wound healing via production of proinflammatory cytokines.

Cell non-autonomous regulation of cerebrovascular aging processes by the somatotropic axis

Age-related cerebrovascular pathologies, ranging from cerebromicrovascular functional and structural alterations to large vessel atherosclerosis, promote the genesis of vascular cognitive impairment and dementia (VCID) and exacerbate Alzheimer's disease. Recent advances in geroscience, including results from studies on heterochronic parabiosis models, reinforce the hypothesis that cell non-autonomous mechanisms play a key role in regulating cerebrovascular aging processes. Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) exert multifaceted vasoprotective effects and production of both hormones is significantly reduced in aging. This brief overview focuses on the role of age-related GH/IGF-1 deficiency in the development of cerebrovascular pathologies and VCID. It explores the mechanistic links among alterations in the somatotropic axis, specific macrovascular and microvascular pathologies (including capillary rarefaction, microhemorrhages, impaired endothelial regulation of cerebral blood flow, disruption of the blood brain barrier, decreased neurovascular coupling, and atherogenesis) and cognitive impairment. Improved understanding of cell non-autonomous mechanisms of vascular aging is crucial to identify targets for intervention to promote cerebrovascular and brain health in older adults.