Intravenous curcumin efficacy on healing and scar formation in rabbit ear wounds under nonischemic, ischemic, and ischemia-reperfusion conditions

Pharmacotherapy for Keloids and Hypertrophic Scars

Keloids (KD) and hypertrophic scars (HTS), which are quite raised and pigmented and have increased vascularization and cellularity, are formed due to the impaired healing process of cutaneous injuries in some individuals having family history and genetic factors. These scars decrease the quality of life (QOL) of patients greatly, due to the pain, itching, contracture, cosmetic problems, and so on, depending on the location of the scars. Treatment/prevention that will satisfy patients' QOL is still under development. In this article, we review pharmacotherapy for treating KD and HTS, including the prevention of postsurgical recurrence (especially KD). Pharmacotherapy involves monotherapy using a single drug and combination pharmacotherapy using multiple drugs, where drugs are administered orally, topically and/or through intralesional injection. In addition, pharmacotherapy for KD/HTS is sometimes combined with surgical excision and/or with physical therapy such as cryotherapy, laser therapy, radiotherapy including brachytherapy, and silicone gel/sheeting. The results regarding the clinical effectiveness of each mono-pharmacotherapy for KD/HTS are not always consistent but rather scattered among researchers. Multimodal combination pharmacotherapy that targets multiple sites simultaneously is more effective than mono-pharmacotherapy. The literature was searched using PubMed, Google Scholar, and Online search engines.

Curcumin and chemokines: mechanism of action and therapeutic potential in inflammatory diseases

Chemokines belong to the family of cytokines with chemoattractant properties that regulate chemotaxis and leukocyte migration, as well as the induction of angiogenesis and maintenance of hemostasis. Curcumin, the major component of the Curcuma longa rhizome, has various pharmacological actions, including anti-inflammatory, immune-regulatory, anti-oxidative, and lipid-modifying properties. Chemokines and chemokine receptors are influenced/modulated by curcumin. Thus, the current review focuses on the molecular mechanisms associated with curcumin's effects on chemoattractant cytokines, as well as putting into context the many studies that have reported curcumin-mediated regulatory effects on inflammatory conditions in the organs/systems of the body (e.g., the central nervous system, liver, and cardiovascular system). Curcumin's effects on viral and bacterial infections, cancer, and adverse pregnancy outcomes are also reviewed.

Role of curcumin in ischemia and reperfusion injury

Ischemia-reperfusion injury (IRI) is an inevitable pathological process after organic transplantations. Although traditional treatments restore the blood supply of ischemic organs, the damage caused by IRI is always ignored. Therefore, the ideal and effective therapeutic strategy to mitigate IRI is warrented. Curcumin is a type of polyphenols, processing such properties as anti-oxidative stress, anti-inflammation and anti-apoptosis. However, although many researches have been confirmed that curcumin can exert great effects on the mitigation of IRI, there are still some controversies about its underlying mechanisms among these researches. Thus, this review is to summarize the protective role of curcumin against IRI as well as the controversies of current researches, so as to clarify its underlying mechanisms clearly and provide clinicians a novel idea of the therapy for IRI.

Transdermal delivery of Protocatechuic aldehyde using hyaluronic acid/gelatin-based microneedles for the prevention and treatment of hypertrophic scars

The formation of hypertrophic scar (HS) involves many pathological processes, such as reduced apoptosis in fibroblasts, excessive collagen deposition by fibroblasts, over-abundant angiogenesis, etc. The therapeutic effects of current treatments targeting one single pathological process are limited. Due to their diverse biological activities, natural products offer a potential solution to this issue. In this study reported herein, we investigated the effects of Protocatechuic aldehyde (PA) on both hypertrophic scar-derived fibroblasts (HSF) and vascular endothelial growth factor (VEGF)-stimulated human umbilical vein endothelial cells (HUVECs). Microneedles (MN) containing PA and hyaluronic acid (HA) or containing PA, HA, and gelatin were prepared by mixing PA stock solution with HA or HA/gelatin at a ratio of 1:10. The HS prevention and treatment outcomes of these HA-PA-MN and HA/gelatin-PA-MN were tested using a rabbit ear HS model. Our data indicate that PA induces apoptosis and reduces collagen deposition in HSF. In addition, PA attenuates VEGF-stimulated angiogenesis of HUVECs. Furthermore, HA-PA-MN or HA/gelatin-PA-MN are able to effectively penetrate the epidermis of the HS tissues and then quickly dissolve, enabling the fast release of PA directly into the dermis of the HS tissues. HA-PA-MN or HA/Gelatin-PA-MN have also been found to effectively prevent or alleviate HS in a rabbit ear HS model. In conclusion, this study demonstrates that PA can be used to prevent and treat HS by simultaneously regulating HSF and HUVECs, which offers a potential novel reagent for HS management.

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.

A review of animal models from 2015 to 2020 for preclinical chronic wounds relevant to human health

SIGNIFICANCE

Chronic wounds fail to heal in a timely manner and exhibit sustained inflammation with slow tissue repair and remodelling. They decrease mobility and quality of life, and remain a major clinical challenge in the long-term care of many patients, affecting 6.5 million individuals annually in the U.S., decreasing mobility and quality of life. Treatment costs are a major burden on the U.S. healthcare system, totalling between $25 and $100 billion annually. Chronic wound severity depends upon several factors such as comorbidities, severity of tissue damage, infection and presence of necrosis and vary greatly in their healing mechanisms. In vivo animal models are critical for studying healing pathways of chronic wounds and seek to replicate clinical factors for trials of topical, systemic, and device-based therapeutics. This comprehensive review discusses murine, rat, lapine, canine, feline and porcine models of chronic wounds.

RECENT ADVANCES

Foundational chronic wound models for several species are discussed together with refinements and advances in the time period between 2015 and 2020 which have the potential for broad utility in investigating biological and device-based wound treatment therapies for human health.

CRITICAL ISSUES

Chronic wounds fail to heal in a timely manner and have differing aetiologies, rendering no single in vivo animal model universally applicable.

FUTURE DIRECTIONS

Further studies are required to develop clinically relevant chronic wound animal model which reflect the clinical reality of the various influences of age, disease, comorbidities and gender on delayed healing and enhance understanding of the biological processes of human wound healing.

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.

Curcumin inhibits liver metastasis of gastric cancer through reducing circulating tumor cells

Primary gastric cancer (PGC) is the fourth most common malignant human cancer and the second leading cause of death worldwide. The majority of the subjects of PGC is diagnosed at a late stage, resulting in poor prognosis and therapeutic outcome, largely attributable to dissemination of tumor cells into circulation as circulating tumor cells (CTCs) and their formation of distal tumor. Curcumin is an active ingredient from the rhizome of the plant Curcuma longa. Here, we assessed whether treatment with Curcumin may reduce the incidence of metastatic tumor formation in liver in mice carrying PGC. We found that Curcumin treatment significantly reduced the presence of CTCs and formation of liver tumor. Mechanistically, Curcumin reduced CXCR4 expression in PGCs in vitro and in vivo, and thus likely inhibited metastasis of PGC through suppression of stromal cell -derived factor-1/CXCR4 signaling. Thus, our study suggests that Curcumin may inhibit liver metastasis of PGC through reducing CTCs.

Liposome-encapsulated statins reduce hypertrophic scarring through topical application

Hypertrophic scar is an important clinical problem with limited therapeutic options. Aside from their roles as 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, statins have also been demonstrated to decrease scarring by reducing connective tissue growth factor (CTGF) expression. However, poor penetrative ability limits their utility as topical treatments for hypertrophic scar. Here, we aim to develop novel statin formulations using liposomes to enhance dermal penetrative ability and to evaluate their efficacy against formation of hypertrophic scar utilizing our validated rabbit ear hypertrophic scar model. Liposomal simvastatin or pravastatin were compounded using a novel, flexible liposomal formulation and applied topically to rabbit ear hypertrophic scars daily from postoperation day (POD) 14 until POD 25. Scar color, including erythema and melanin, was measured using reflectance spectrophotometry on POD 28, and scar tissue was harvested for evaluation of scar elevation index as well as gene and protein expression. Human foreskin fibroblasts were also treated with statin formulations and CCN2 expression was determined by quantitative PCR. Both simvastatin and pravastatin were efficiently encapsulated in liposomes, forming nanometer-scale particles possessing highly negative charges. Topical treatment with liposomal simvastatin and pravastatin at 6.5% concentration significantly reduced scar elevation index and decreased type I/III collagen content and myofibroblast persistence in the wound. The erythema/vascularity of scars was reduced by liposomal statin treatment, with concomitant decrease of CD31 expression as measured histologically. Expression levels of transcripts encoding CTGF, collagen I, and collagen III collagen in scar tissue were also decreased by liposomal pravastatin treatment, as were myofibroblast persistence and the type I/III collagen ratio as assessed by immunofluorescence and picrosirus red staining, respectively. Treatment of human foreskin fibroblasts with simvastatin or with liposome-encapsulated pravastatin resulted in decreased expression of transcript encoding CTGF. Overall, our novel statin formulations encapsulated in liposomes were successfully delivered through topical application, significantly reducing hypertrophic scarring in a rabbit ear model.

Topical application of curcumin regulates the angiogenesis in diabetic-impaired cutaneous wound

Diabetic wound characterizes with a delayed repair as a result of the lack of neoangiogenesis and the excess of inflammation. Natural products such as curcumin have shown great promises in their regulatory potentials on inflammation and angiogenesis. However, natural agents have several shortages in their bioavailability and stability when used in vivo. In this study, we have evaluated the efficacy of a topical formulation of curcumin in the enhancement of diabetic wound repair. Streptozocin-induced diabetic mice were wounded, and cream of curcumin (1%) was applied topically to wounds twice daily for different treatment periods. Inflammation, neoangiogenesis, and re-epithelialization were evaluated in each experimental group. Wounds of animals treated with curcumin showed an enhanced neoangiogenesis. Application of topical curcumin also increased the expression level of RelA as the main subunit of the nuclear factor-κB (NF-κB) signalling pathway. However, no significant effects on macrophage polarization and re-epithelialization were observed in the curcumin-treated animals. Our study using a higher concentration of curcumin in the form of a topical cream further confirmed the efficacy of curcumin as an angiogenesis-promoting agent; however, it also conveyed uncertainty over the claimed regulatory effects of curcumin on inflammation. SIGNIFICANCE OF THE STUDY: Diabetes results in several complications such as impaired cutaneous wound repair. Excess of inflammation and lack of angiogenesis are among the main causes of delayed healing in diabetes. Curcumin is famous for its anti-inflammatory properties. However, when in the body curcumin has shown to have a limited benefit unless in high-dosage consumes. This is because of its poor absorption from digestive system and its bioavailability. In this study, we have used a topical formulation of curcumin at a relatively high concentration to enhance the healing of a diabetic wound in an animal model of diabetes. We also have studied different cellular and molecular mechanisms by which curcumin may help the wound repair. Our results re-emphasize the proangiogenic potential of curcumin in diabetic wound environment.

Experimental models for cutaneous hypertrophic scar research

Human skin wound repair may result in various outcomes with most of them leading to scar formation. Commonly seen in many cutaneous wound healing cases, hypertrophic scars are considered as phenotypes of abnormal wound repair. To prevent the formation of hypertrophic scars, efforts have been made to understand the mechanism of scarring following wound closure. Numerous in vivo and in vitro models have been created to facilitate investigations into cutaneous scarring and the development of antiscarring treatments. To select the best model for a specific study, background knowledge of the current models of hypertrophic scars is necessary. In this review, we describe in vivo and in vitro models for studying hypertrophic scars, as well as the distinct characteristics of these models. The choice of models for a specific study should be based on the characteristics of the model and the goal of the study. In general, in vivo animal models are often used in phenotypical scar formation analysis, development of antiscarring treatment, and functional analyses of individual genes. In contrast, in vitro models are chosen to pathway identification during scar formation as well as in high-throughput analysis in drug development. Besides helping investigators choose the best scarring model for their research, the goal of this review is to provide knowledge for improving the existing models and development of new models. These will contribute to the progress of scarring studies.

Hyperosmolar potassium inhibits myofibroblast conversion and reduces scar tissue formation

Scar formation is a natural result of almost all wound healing in adult mammals. Unfortunately, scarring disrupts normal tissue function and can cause significant physical and psychological distress. In addition to improving surgical techniques to limit scar formation, several therapies are under development towards the same goal. Many of these treatments aim to disrupt transforming growth factor β1 (TGFβ1) signaling, as this is a critical control point for fibroblast differentiation into myofibroblasts; a contractile cell that organizes synthesized collagen fibrils into scar tissue. The present study aimed to examine the role of hyperosmolar potassium gluconate (KGluc) on fibroblast function in skin repair. KGluc was first determined to negatively regulate fibroblast proliferation, metabolism, and migration in a dose-dependent manner in vitro. Increasing concentrations of KGluc also inhibited differentiation into myofibroblasts, suggesting that local KGluc treatment might reduce fibrosis. KGluc delivery was confirmed via loading into collagen hydrogels and used to treat a full thickness skin wound in mice. KGluc qualitatively slowed initial closure of the wounds and resulted in tissue that more closely resembled mature, healthy skin (epidermal thickness and dermal-epidermal morphology) when compared to unloaded collagen hydrogels. KGluc treatment significantly reduced the number of myofibroblasts within the dermis while upregulated blood vessel density with respect to unloaded hydrogels, likely a result of disruption of TGFβ1 signaling. Taken together, these data demonstrate the effectiveness of KGluc treatment on skin wound healing and suggest that this may be an efficient treatment to limit scar formation.

In vivo comparison of wound healing and scar treatment effect between curcumin-oligochitosan nanoparticle complex and oligochitosan-coated curcumin-loaded-liposome

This study aimed to compare the in vivo effectiveness between curcumin-oligochitosan nanoplexes (CUR-OCH nanoplexes) and oligochitosan-coated curcumin-encapsulated liposomes (OCH-Lip-CUR) with respect to wound healing and scar treatment. Firstly, CUR-OCH nanoplexes was prepared by drug-polysaccharide complexation method and OCH-Lip-CUR was prepared by a combining method of lipid-film hydration and sonication. Their in vitro cytotoxicity and in vivo wound healing and scar treatment effectiveness were evaluated using 3T3 cells and mice Mus musculus var. Albino, respectively. The resutls indicated that both of them were in nanosize with a moderate PDI (less than 0.3), and exhibited negligible cytotoxicity at low CUR concentration (0.01 mg/mL). Moreover, their application onto wounds resulted in faster healing and higher scar treatment effectiveness than control samples. Interestingly, OCH-Lip-CUR exhibited higher in vivo effectiveness than CUR-OCH nanoplexes. However, based on their own advantages, both of them were good candidates for a commercial formulation for wound healing and scar treatment.

Comparison of Enalapril, Candesartan and Intralesional Triamcinolone in Reducing Hypertrophic Scar Development: An Experimental Study

BACKGROUND

The purpose of this study was to compare the effects of oral enalapril, an angiotensin-converting enzyme inhibitor (ACE-I), oral candesartan, an angiotensin receptor blocker (ARB), and intralesional corticosteroid treatments in reducing scar formation.

METHODS

Twenty male rabbits were divided into five study groups: A (sham), B (control), C (ACE-I), D (ARB) and E (intralesional corticosteroid). The rabbit ear hypertrophic scar model was used. The hypertrophic scars were photographed and analyzed with the program ImageJ quantitatively to determine the degree of collagen fibers. The scar elevation index (SEI) was calculated at the end of the 40th day. Tissue samples were stained with hematoxylin and eosin and Masson's trichrome and examined under light microscopy for the determination of fibroblast number, epithelization, vascularization, inflammation and fibrosis.

RESULTS

The SEI was the highest in the control group with the highest number of fibroblasts under the epithelium. In the steroid group, the SEI was significantly lower than both the ACE-I (p: 0.02) and ARB (p: 0.001) groups. The density of type 1 collagen fibers was the lowest in the control group, whereas type 3 collagen fibers were highest in that group. The ACE-I and ARB groups were similar regarding densities of type 1 and type 3 collagen fibers. The density of type 1 collagen fibers was the highest in the steroid group, whereas the density of type 3 collagen fibers was the lowest in that group.

CONCLUSIONS

Enalapril, candesartan and intralesional steroid therapies were all effective in reducing scar tissue development; however, enalapril and steroid groups revealed better results.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each article. 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 .

Local Application of Statins Significantly Reduced Hypertrophic Scarring in a Rabbit Ear Model

BACKGROUND

We previously showed that intradermal injection of statins is a successful treatment for hypertrophic scarring. Topical application has many advantages over intradermal injection. In this study, we demonstrate the efficacy of topical statin treatment in reducing scar in our validated rabbit ear scar model.

METHODS

Twenty New Zealand White rabbits were divided into 2 study groups, with 6 rabbits receiving 10 μm pravastatin intradermally at postoperative days 15, 18, and 21, and 14 rabbits receiving 0.4%, 2%, and 10% simvastatin topical application at postoperative days 14-25. Four or 6 full-thickness circular dermal punches 7 mm in diameter were made on the ventral surface of the ear down to but not including the perichondrium. Specimens were collected at 28 days to evaluate the effects of statins on hypertrophic scarring.

RESULTS

Treatment with pravastatin intradermal administration significantly reduced scarring in terms of scar elevation index. Topical treatment with both medium- and high-dose simvastatin also significantly reduced scarring. High-dose simvastatin topical treatment showed a major effect in scar reduction but induced side effects of scaling, erythema, and epidermal hyperplasia, which were improved with coapplication of cholesterol. There is a dose response in scar reduction with low-, medium- and high-dose simvastatin topical treatment. High-dose simvastatin treatment significantly reduced the messenger ribonucleic acid (mRNA) expression of connective tissue growth factor, consistent with our previously published work on intradermally injected statins. More directly, high-dose simvastatin treatment also significantly reduced the mRNA expression of collagen 1A1.

CONCLUSIONS

Topical simvastatin significantly reduces scar formation. The mechanism of efficacy for statin treatment through interference with connective tissue growth factor mRNA expression was confirmed.

Biomaterials and tissue engineering for scar management in wound care

Scars are a natural and unavoidable result from most wound repair procedures and the body's physiological healing response. However, they scars can cause considerable functional impairment and emotional and social distress. There are different forms of treatments that have been adopted to manage or eliminate scar formation. This review covers the latest research in the past decade on using either natural agents or synthetic biomaterials in treatments for scar reduction.

Oxidized cyclodextrin-functionalized injectable gelatin hydrogels as a new platform for tissue-adhesive hydrophobic drug delivery

Dual-functional injectable gelatin-based hydrogels utilizing oxidized β-cyclodextrin show high adhesiveness and hydrophobic drug supply.

Catanionic lipid nanosystems improve pharmacokinetics and anti-lung cancer activity of curcumin

Novel catanionic lipid nanosystems (CLNs) incorporating curcumin (CCM) were developed, and improvements in pharmacokinetics and enhanced anti-lung cancer activity were observed. CCM was present in a lipid matrix surrounded by cationic, anionic and zwitterionic surfactants, forming the core-shell nanosystems. Compared with free CCM, the CCM-CLNs had much higher oral and intravenous bioavailabilities due to enhanced absorption and reduced clearance. The CCM-CLNs exhibited greater cytotoxicity in Lewis lung cancer (LLC) cells, which might have been due to increased antiproliferative, proapoptotic and anti-invasive activities and induction of cell cycle arrest. The CCM-CLNs increased the antitumor efficacy of CCM and decreased the tumor growth rate in tumor-bearing mice. This is the first report of induction of apoptosis in LLC cells by CCM through the PI3K/Akt/FoxO1/Bim signaling pathway. Catanionic lipid nanocarriers show promise for the therapeutic delivery of insoluble anti-tumor drugs.

Curcumin Reduces the Noise-Exposed Cochlear Fibroblasts Apoptosis

Introduction The structural changes underlying permanent noise-induced hearing loss (NIHL) include loss of the sensory hair cells, damage to their stereocilia, and supporting tissues within the cochlear lateral wall.

Objective The objective of this study is to demonstrate curcumin as a safe and effective therapeutic agent in the prevention and treatment for fibroblasts damage within the cochlear supporting tissues and lateral wall through cell death pathway.

Methods We divided 24 Rattus norvegicus into 4 groups, Group 1: control; Group 2: noise (+); Group 3: noise (+), 50 mg/day curcumin (+); Group 4: noise (+), 100 mg/day curcumin (+). We provided the noise exposure dose at 100 dB SPL for two hours over two weeks and administered the curcumin orally over two weeks. We examined all samples for the expressions of calcineurin, nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), and apoptotic index of cochlear fibroblasts.

Results We found significant differences for the expressions of calcineurin (p < 0.05) in all groups, significant differences for the expressions of NFATc1 (p < 0.05) in all groups, except in Groups 1 and 4, and significant differences for the apoptotic index (p < 0.05) in all groups.

Conclusion Curcumin proved to be potentially effective in the prevention and treatment for fibroblasts damage within the cochlear supporting tissues and lateral wall regarding the decreased expression of calcineurin, NFATc1, and apoptotic index of cochlear fibroblasts.