Scar-reducing effects of gambogenic acid on skin wounds in rabbit ears

The role of macrophages in hypertrophic scarring: molecular to therapeutic insights

Hypertrophic Scar (HS) is a common fibrotic disease of the skin, usually caused by injury to the deep dermis due to trauma, burns, or surgical injury. The main feature of HS is the thickening and hardening of the skin, often accompanied by itching and pain, which seriously affects the patient's quality of life. Macrophages are involved in all stages of HS genesis through phenotypic changes. M1-type macrophages primarily function in the early inflammatory phase by secreting pro-inflammatory factors, while M2-type macrophages actively contribute to tissue repair and fibrosis. Despite advances in understanding HS pathogenesis, the precise mechanisms linking macrophage phenotypic changes to fibrosis remain incompletely elucidated. This review addresses these gaps by discussing the pathological mechanisms of HS formation, the phenotypic changes of macrophages at different stages of HS formation, and the pathways through which macrophages influence HS progression. Furthermore, emerging technologies for HS treatment and novel therapeutic strategies targeting macrophages are highlighted, offering potential avenues for improved prevention and treatment of HS.

Losartan in Situ Forming Gel as a New Treatment for Hypertrophic Scars

Hypertrophic scars are defined as visible lesions formed by excessive wound healing that cause cosmetic and, in some cases, functional challenges in patients. This study aimed to assess the efficacy of intralesional injections of losartan-loaded in situ forming gel and compare it with the common treatment (triamcinolone) in preventing scar formation. The formulation was prepared using a thermosensitive PLGA-PEG-PLGA triblock copolymer. Ear scar tissue in rabbits represented the hypertrophic scar, and the animals were treated with three treatments in three groups. Nine weeks following the single treatment, images of the scars were obtained and quantitatively analyzed using ImageJ and light microscopy was used to evaluate the fibroblast cell number, vascularization, inflammation and collagen deposition and fibrosis in H&E-stained sample tissue. According to the results based on the ImageJ and the Vancouver criteria, the losartan in situ forming gel (F-LG) indicated significantly higher improving effects on decreased vascularity and pigmentation in comparison with triamcinolone (F-TA) and placebo as a control (F-Ctl), although the effect F-LG was almost similar to F-TA on pliability and scar height, and they were better than the control. Histological findings showed F-LG and F-TA have less inflammatory and fibroblast cells compared to F-Ctl. Also, results indicated the dermal layers of the F-TA and F-LG groups' scar were thinner, and the deposition of collagens was reduced compared to the control. Consequently, F-LG was found to be an effective treatment in reducing scarring and promoting wound healing.No Level Assigned This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Multifunctional Nanofiber Membranes Constructed by Microfluidic Blow-Spinning to Inhibit Scar Formation at Early Intervention Stage

Pathological scarring has been a challenge in skin injury repair since ancient times, and prophylactic treatment in the early stages of wound healing usually results in delayed wound healing. In this study, poly(ethylene oxide) (PEO) and chitosan (CTS) were used as carrier materials to construct multifunctional pirfenidone (PFD)/CTS/PEO (PCP) nanofiber membranes (NFMs) loaded with PFD by microfluidic blow-spinning (MBS). MBS is a good method for quickly, safely, and greenly constructing large-area manufacturing of inexpensive NFMs. PCP NFMs were uniform in external morphology, with diameters ranging from 200 to 500 nm. The encapsulation efficiency of the drug-loaded PCP NFMs was above 80%, which had a good slow release, visualization, water absorption, and biocompatibility. The inhibitory effect of PCP NFMs on normal human dermal fibroblasts was dose-dependent and inhibited the expression of the transforming growth factor-β1/SMAD family member 3 (TGF-β1/SMAD3) signaling pathway. PCP NFMs showed significant antibacterial effects against both Staphylococcus aureus and Escherichia coli. In the rabbit ear scar experiment, the wound healed about 70% on day 5 and almost completely on day 10 after PCP-3 NFMs treatment, with the thinnest scar tissue, skin color, tenderness close to normal tissue, and a Vancouver scar scale score of less than 5. PCP-3 NFMs had good effects on anti-inflammatory, wound healing, and collagen-I deposition reducing effects. In conclusion, PCP-3 NFMs can both promote wound healing and intervene to inhibit pathological scarring in advance, making them a potential multifunctional wound dressing for early prevention and treatment of pathological scarring.

Ultra-pH-sensitive nanoparticle of gambogenic acid for tumor targeting therapy via anti-vascular strategy plus immunotherapy

Although the combination of anti-vascular strategy plus immunotherapy has emerged as the optimal first-line treatment of hepatocellular carcinoma, lack of tumor targeting leads to low antitumor efficacy and serious side effect. Here, we report an ultra-pH-sensitive nanoparticle of gambogenic acid (GNA) encapsulated by poly(ethylene glycol)-poly(2-azepane ethyl methacrylate) (PEG-PAEMA) for tumor-targeting combined therapy of anti-vascular strategy plus immunotherapy. PEG-PAEMA-GNA nanoparticle was quite stable at pH 7.4 for 30 d. In contrast, it exerted size shrinkage, charge reversal and the release of GNA at pH 6.7 within 24 h. Moreover, PEG-PAEMA-GNA significantly enhanced the anti-vascular activity, membrane-disruptive capability and pro-apoptosis when pH changed from 7.4 to 6.7. Western blot analysis exhibits that PEG-PAEMA and its GNA nanoparticle facilitated the phosphorylation of STING protein. In vivo assays show that PEG-PAEMA-GNA not only displayed much higher tumor inhibition of 92 % than 37 % of free GNA, but also inhibited tumor vasculature, promoted the maturation of dendritic cells and recruited more cytotoxic t-lymphocytes for sufficient anti-vascular therapy and immunotherapy. All these results demonstrate that PEG-PAEMA-GNA displayed tumor-targeting combined treatment of anti-vascular therapy and immunotherapy. This study offers a simple and novel method for the combination of anti-vascular therapy and immunotherapy with high selectivity towards tumor.

Preparation of Compound Salvia miltiorrhiza-Blumea balsamifera Nanoemulsion Gel and Its Effect on Hypertrophic Scars in the Rabbit Ear Model

Hypertrophic scars (HS) still remain an urgent challenge in the medical community. Traditional Chinese medicine (TCM) has unique advantages in the treatment of HS. However, due to the natural barrier of the skin, it is difficult for the natural active components of TCM to more effectively penetrate the skin and exert therapeutic effects. Therefore, the development of an efficient drug delivery system to facilitate enhanced transdermal absorption of TCM becomes imperative for its clinical application. In this study, we designed a compound Salvia miltiorrhiza-Blumea balsamifera nanoemulsion gel (CSB-NEG) and investigated its therapeutic effects on rabbit HS models. The prescription of CSB-NEG was optimized by single-factor, pseudoternary phase diagram, and central composite design experiments. The results showed that the average particle size and PDI of the optimized CSB-NE were 46.0 ± 0.2 nm and 0.222 ± 0.004, respectively, and the encapsulation efficiency of total phenolic acid was 93.37 ± 2.56%. CSB-NEG demonstrated excellent stability and skin permeation in vitro and displayed a significantly enhanced ability to inhibit scar formation compared to the CSB physical mixture in vivo. After 3 weeks of CSB-NEG treatment, the scar appeared to be flat, pink, and flexible. Furthermore, this treatment also resulted in a decrease in the levels of the collagen I/III ratio and TGF-β1 and Smad2 proteins while simultaneously promoting the growth and remodeling of microvessels. These findings suggest that CSB-NEG has the potential to effectively address the barrier properties of the skin and provide therapeutic benefits for HS, offering a new perspective for the prevention and treatment of HS.

Unveiling Gambogenic Acid as a Promising Antitumor Compound: A Review

Gambogenic acid is a derivative of gambogic acid, a polyprenylated xanthone isolated from Garcinia hanburyi. Compared with the more widely studied gambogic acid, gambogenic acid has demonstrated advantages such as a more potent antitumor effect and less systemic toxicity than gambogic acid according to early investigations. Therefore, the present review summarizes the effectiveness and mechanisms of gambogenic acid in different cancers and highlights the mechanisms of action. In addition, drug delivery systems to improve the bioavailability of gambogenic acid and its pharmacokinetic profile are included. Gambogenic acid has been applied to treat a wide range of cancers, such as lung, liver, colorectal, breast, gastric, bladder, and prostate cancers. Gambogenic acid exerts its antitumor effects as a novel class of enhancer of zeste homolog 2 inhibitors. It prevents cancer cell proliferation by inducing apoptosis, ferroptosis, and necroptosis and controlling the cell cycle as well as autophagy. Gambogenic acid also hinders tumor cell invasion and metastasis by downregulating metastasis-related proteins. Moreover, gambogenic acid increases the sensitivity of cancer cells to chemotherapy and has shown effects on multidrug resistance in malignancy. This review adds insights for the prevention and treatment of cancers using gambogenic acid.

Effects of ultrashort wave diathermy on skin wounds in rabbit ears

PURPOSE

Ultrashort wave diathermy (USWD) is commonly used in diseases associated with osteoarticular and soft tissue injuries. However, while accelerating wound healing and preventing joint stiffness, there have been few reports on whether it leads to excessive hypertrophic scarring. The aim was to investigate the effects of different doses of USWD on hypertrophic scars.

MATERIALS AND METHODS

A rabbit model of hypertrophic scars was used to determine which dose of USWD reduced scar hyperplasia. The scar thickness was calculated using Sirius red staining. All protein expression levels were determined by western blotting, including fibrosis, collagen deposition, and neoangiogenesis related proteins. Subsequently, flow cytometry and ELISAs were used to determine the proportions of macrophage and inflammatory levels.

RESULTS

The wounds with USWD in histopathology showed the dermis was more markedly thickened in the 120 mA group, whereas the wounds with the 60 mA were less raised, comparing with the 0 mA; all detected protein levels were increased significantly, the 120 mA group comparing with the others, including heat shock, fibrosis, and neoangiogenesis, whereas the collagen deposition relative protein levels were decreased, the 60 mA group comparing with Sham group; Finally, in the proportion of macrophages and inflammatory levels the 120 mA group were the highest, and the group Sham was lower than group 60 mA.

CONCLUSIONS

In hypertrophic scars, the 60 mA USWD could relieve scar formation and inflammatory reactions; however, higher doses could result in opposite consequences.

Gambogenic acid induces cell death in human osteosarcoma through altering iron metabolism, disturbing the redox balance, and activating the P53 signaling pathway

Osteosarcoma (OS) is the most common primary bone malignancy in children and adolescents with extremely poor prognosis. Gambogenic acid (GNA), one of the major bioactive ingredients isolated from Gamboge, has been shown to possess a multipotent antitumor effect, its activity on OS remains unclear yet. In this study, we found that GNA could trigger multiple cell death modalities, including ferroptosis and apoptosis in human OS cells, reduce the cell viability, inhibit the proliferation and invasiveness. Furthermore, GNA provoked oxidative stress leading to GSH depletion-inducing ROS generation and lipid peroxidation, altered iron metabolism represented by the induction of labile iron, mitochondrial membrane potential decreased, mitochondrial morphological changed, decreased the cell viability. In addition, ferroptosis inhibitors (Fer-1) and apoptosis inhibitors (NAC) can partially reversed GNA' s effects on OS cells. Further investigation showed that GNA augmented the expression of P53, bax, caspase 3 and caspase 9 and decreased the expression of Bcl-2, SLC7A11 and glutathione peroxidase-4 (GPX4). In vivo, GNA was showed to delay tumor growth significantly in axenograft osteosarcoma mouse model. In conclusion, this study reveals that GNA simultaneously triggers ferroptosis and apoptosis in human OS cells by inducing oxidative stress via the P53/SLC7A11/GPX4 axis.

Smart anti-vascular nanoagent induces positive feedback loop for self-augmented tumor accumulation

How to achieve efficient drug accumulation in the tumor with low vascular density is a great challenge but the key to push the limit of anti-vascular therapeutic efficacy. Herein, we report a charge-reversible nanoparticles of gambogenic acid (CRNP-GNA) that would induce the positive feedback loop between increased tumor vascular permeability and improved drug accumulation. This positive feedback loop would remarkably improve tumor vascular permeability for efficient drug accumulation through few residue vessels. As compared to its charge-irreversible analogue in the latter injections, the accumulation in tumor and vascular permeability and retention indexes (VPRI) in CRNP-GNA group respectively boosted from nearly equal to 8.32 and 60 times, while its tumorous microvessel density decreased from nearly equal to only 7%. The self-augmented accumulation consequently amplified the antitumor efficacy via multiple pathways of anti-angiogenesis, vascular disruption and pro-apoptosis, where 5 out of 6 tumors in animal models were completely cured by CRNP-GNA. This work confirms that the underlying positive feedback loop for anti-vascular therapy could be induced by charge-reversible drug delivery nanosystem to achieve efficient and self-augmented drug accumulation even in the tumor with few vessels. It provides a novel strategy to conquer the dilemma between anti-vascular efficacy and drug accumulation.

EGCG inhibits hypertrophic scar formation in a rabbit ear model

OBJECTIVE

Hypertrophic scarring is a common skin fibro-proliferative disease, but currently there has no satisfactory drugs for anti-scar treatments. Previous study showed that epigallocatechin gallate (EGCG), the main catechin in green tea, improved wound healing and tissue fibrosis in both rats and mice. In the present study, the therapeutic effects of EGCG on hypertrophic scar were analyzed using a rabbit ear hypertrophic scar model.

MATERIALS

A rabbit ear model of hypertrophic scarring was used. DMSO, 0.5 mg EGCG/wound, 1.0 mg EGCG/wound or triamcinolone were injected subcutaneously once a week for 4 weeks. The scar elevation index (SEI) was measured using HE staining images, the collagen fibers were examined by Masson' trichrome staining images, and the number of capillaries in hypertrophic scar were calculated by CD31 staining images. The mRNA levels in the scar tissues were detected by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Gross observation and histological evaluation showed the inhibitory effects of EGCG on hypertrophic scar formation at both doses, and decreased scar height and SEI were detected. EGCG also attenuated the mean collagen area fraction and decreased the number of capillaries in scar tissues. qRT-PCR revealed that EGCG significantly inhibited the mRNA expression of TGF-β1, Col I, Col III, α-SMA, and eNOS.

CONCLUSION

EGCG may serve as a useful candidate therapeutic drug for hypertrophic scar via inhibiting fibrotic gene expression and suppressing angiogenesis.

Automated Structural Analysis and Quantitative Characterization of Scar Tissue Using Machine Learning

An analysis of scar tissue is necessary to understand the pathological tissue conditions during or after the wound healing process. Hematoxylin and eosin (HE) staining has conventionally been applied to understand the morphology of scar tissue. However, the scar lesions cannot be analyzed from a whole slide image. The current study aimed to develop a method for the rapid and automatic characterization of scar lesions in HE-stained scar tissues using a supervised and unsupervised learning algorithm. The supervised learning used a Mask region-based convolutional neural network (RCNN) to train a pattern from a data representation using MMDetection tools. The K-means algorithm characterized the HE-stained tissue and extracted the main features, such as the collagen density and directional variance of the collagen. The Mask RCNN model effectively predicted scar images using various backbone networks (e.g., ResNet50, ResNet101, ResNeSt50, and ResNeSt101) with high accuracy. The K-means clustering method successfully characterized the HE-stained tissue by separating the main features in terms of the collagen fiber and dermal mature components, namely, the glands, hair follicles, and nuclei. A quantitative analysis of the scar tissue in terms of the collagen density and directional variance of the collagen confirmed 50% differences between the normal and scar tissues. The proposed methods were utilized to characterize the pathological features of scar tissue for an objective histological analysis. The trained model is time-efficient when used for detection in place of a manual analysis. Machine learning-assisted analysis is expected to aid in understanding scar conditions, and to help establish an optimal treatment plan.

Therapeutic Strategies by Regulating Interleukin Family to Suppress Inflammation in Hypertrophic Scar and Keloid

Hypertrophic scar (HS) and keloid are fibroproliferative disorders (FPDs) of the skin due to aberrant wound healing, which cause disfigured appearance, discomfort, dysfunction, psychological stress, and patient frustration. The unclear pathogenesis behind HS and keloid is partially responsible for the clinical treatment stagnancy. However, there are now increasing evidences suggesting that inflammation is the initiator of HS and keloid formation. Interleukins are known to participate in inflammatory and immune responses, and play a critical role in wound healing and scar formation. In this review, we summarize the function of related interleukins, and focus on their potentials as the therapeutic target for the treatment of HS and keloid.