Scar and contracture: biological principles

Targeting Diverse Wounds and Scars: Recent Innovative Bio-design of Microneedle Patch for Comprehensive Management

Wounds and the subsequent formation of scars constitute a unified and complex phased process. Effective treatment is crucial; however, the diverse therapeutic approaches for different wounds and scars, as well as varying treatment needs at different stages, present significant challenges in selecting appropriate interventions. Microneedle patch (MNP), as a novel minimally invasive transdermal drug delivery system, has the potential for integrated and programmed treatment of various diseases and has shown promising applications in different types of wounds and scars. In this comprehensive review, the latest applications and biotechnological innovations of MNPs in these fields are thoroughly explored, summarizing their powerful abilities to accelerate healing, inhibit scar formation, and manage related symptoms. Moreover, potential applications in various scenarios are discussed. Additionally, the side effects, manufacturing processes, and material selection to explore the clinical translational potential are investigated. This groundwork can provide a theoretical basis and serve as a catalyst for future innovations in the pursuit of favorable therapeutic options for skin tissue regeneration.

An Updated Review of Hypertrophic Scarring

Hypertrophic scarring (HTS) is an aberrant form of wound healing that is associated with excessive deposition of extracellular matrix and connective tissue at the site of injury. In this review article, we provide an overview of normal (acute) wound healing phases (hemostasis, inflammation, proliferation, and remodeling). We next discuss the dysregulated and/or impaired mechanisms in wound healing phases that are associated with HTS development. We next discuss the animal models of HTS and their limitations, and review the current and emerging treatments of HTS.

Loureirin A Exerts Antikeloid Activity by Antagonizing the TGF-β1/Smad Signalling Pathway

It has been recently shown that loureirin A (LA), a major active component of resina draconis, might be effective in the prevention and treatment of liver fibrosis. We examined whether LA could inhibit the formation of keloids. To investigate the pharmacological effects of loureirin A on keloid formation and the underlying mechanisms. CellTiter-Blue viability assays were used to examine the proliferation of keloid fibroblasts (KFs) that were treated with LA. Fibroblast migration was evaluated using a cell migration assay. Immunofluorescence staining was used to measure the expression of α-SMA in KFs. RT-qPCR was used to evaluate the mRNA expression of Col-I, Col-III, α-SMA, Bax, and Caspase-3, while Western blotting was used to evaluate the protein expression of Col-I, Col-III, α-SMA, Bax, Caspase-3, p-Smad2, and p-Smad3. LA inhibited the proliferation of KFs and suppressed the migration and TGF-β1-induced myofibroblast differentiation of KFs. In addition, LA downregulated the mRNA and protein levels of Col-I, Col-III, and α-SMA while promoting the mRNA and protein levels of Bax and Caspase-3. Moreover, LA downregulated the protein levels of p-Smad2 and p-Smad3 in cultured TGF-β1-treated KFs ex vivo. These results show that LA has an antikeloid effect on KFs by suppressing the TGF-β1/Smad signalling pathway. Our findings suggest that LA may be a potential candidate drug for the prevention and treatment of keloids.

Strategies to Minimize Surgical Scarring: Translation of Lessons Learned from Bedside to Bench and Back

Significance: An understanding of the physiology of wound healing and scarring is necessary to minimize surgical scar formation. By reducing tension across the healing wound, eliminating excess inflammation and infection, and encouraging perfusion to healing areas, surgeons can support healing and minimize scarring. Recent Advances: Preoperatively, newer techniques focused on incision placement to minimize tension, skin sterilization to minimize infection and inflammation, and control of comorbid factors to promote a healing process with minimal scarring are constantly evolving. Intraoperatively, measures like layered closure, undermining, and tissue expansion can be taken to relieve tension across the healing wound. Appropriate suture technique and selection should be considered, and finally, there are new surgical technologies available to reduce tension across the closure. Postoperatively, the healing process can be supported as proliferation and remodeling take place within the wound. A balance of moisture control, tension reduction, and infection prevention can be achieved with dressings, ointments, and silicone. Vitamins and corticosteroids can also affect the scarring process by modulating the cellular factors involved in healing. Critical Issues: Healing with no or minimal scarring is the ultimate goal of wound healing research. Understanding how mechanical tension, inflammation and infection, and perfusion and hypoxia impact profibrotic pathways allows for the development of therapies that can modulate cytokine response and the wound extracellular microenvironment to reduce fibrosis and scarring. Future Directions: New tension-off loading topical treatments, laser, and dermabrasion devices are under development, and small molecule therapeutics have demonstrated scarless wound healing in animal models, providing a promising new direction for future research aimed to minimize surgical scarring.

The Thenar Crease Skin Graft: A Novel Addition to "Camouflage" Grafts of the Hand

Palmar skin defects of the hand are common. When wound conditions are favorable, glabrous skin grafting provides ideal resurfacing-simple, predictable, and excellent esthetic outcome. Glabrous skin grafts are however confined to small sizes from limited donor sites. We present a novel technique of harvesting full-thickness skin grafts from the thenar crease and report the outcome of our cases. We provide further insights to adapt the technique to a variety of clinical scenarios-degloving injuries and shaving injuries of the finger including subcomplete pulp skin loss. Graft size is up to 75 mm by 10 mm, with tension-free donor site closure. We further report the operative experience, functional and esthetic outcome. The technique is fast, versatile, and provides large surface areas of good quality glabrous skin in a single-stage procedure. It will sit well in the armamentarium of the hand surgeon.

A Novel Bespoke Hypertrophic Scar Treatment: Actualizing Hybrid Pressure and Silicone Therapies with 3D Printing and Scanning

The treatment of hypertrophic scars (HSs) is considered to be the most challenging task in wound rehabilitation. Conventional silicone sheet therapy has a positive effect on the healing process of HSs. However, the dimensions of the silicone sheet are typically larger than those of the HS itself which may negatively impact the healthy skin that surrounds the HS. Furthermore, the debonding and displacement of the silicone sheet from the skin are critical problems that affect treatment compliance. Herein, we propose a bespoke HS treatment design that integrates pressure sleeve with a silicone sheet and use of silicone gel using a workflow of three-dimensional (3D) printing, 3D scanning and computer-aided design, and manufacturing software. A finite element analysis (FEA) is used to optimize the control of the pressure distribution and investigate the effects of the silicone elastomer. The result shows that the silicone elastomer increases the amount of exerted pressure on the HS and minimizes unnecessary pressure to other parts of the wrist. Based on this treatment design, a silicone elastomer that perfectly conforms to an HS is printed and attached onto a customized pressure sleeve. Most importantly, unlimited scar treating gel can be applied as the means to optimize treatment of HSs while the silicone sheet is firmly affixed and secured by the pressure sleeve.

A Rodent Model of Hypertrophic Scarring: Splinting of Rat Wounds

Human hypertrophic scars are the result of imperfect healing of skin, which is particularly evident from the scars developing after severe burns. In contrast, mouse and rat full-thickness skin wounds heal normally without forming visible scar tissue, which reduces the suitability of rodent models for the study of skin scarring. We here provide a simple procedure to splint the edges of full-thickness rodent skin with a sutured plastic frame that prevents wound closure by granulation tissue contraction. The resulting mechanical tension in the wound bed and the lack of neo-epithelium amplify myofibroblast formation and generate hypertrophic features, not unlike those of human skin. In addition to producing scar tissue, the splint provides a reservoir that can be used for the delivery of cellular and acellular wound treatment regimen. Despite being simple and almost historical, wound splinting is a robust and reliable model to study myofibroblast biology.

Expression of collagen type III in healing tympanic membrane

OBJECTIVES

Type III collagen plays significant role in skin wound healing, forming provisional matrix guiding the inflammatory cells and fibroblasts into the wound site. Our preliminary study performed on rat's tympanic membrane (TM) using Rat Wound Healing RT2 Profiler PCR Array revealed up-regulated expression of collagen type III α1 chain mRNA also during healing of TM. This study was undertaken to confirm and evaluate collagen type III protein expression and distribution during TM healing process.

METHODS

Sixty rats were used, of which 10 served as controls and the others had their TM perforated. The experimental animals were divided into five subgroups on the basis of time points (03, 06, 09, 14, 20 day after injury). Videootoscopy and histology were employed to assess morphology of the healing process. The expression of collagen type III was evaluated using Western blot analysis and its tissue localization was determined by the immunohistochemical method.

RESULTS

The expression of collagen type III remained on the same level as in control TM up to day 06. On day 09 abrupt (p = 0.01) increase of the collagen type III expression was observed and it maintained on the same level to the end of observation period. In perforated TM collagen type III was detected in the healing area along the perforation border and around dilated blood vessels. On day 14 and 20 collagen type III was found in the connective tissue filling up the TM previous defect.

CONCLUSIONS

Taking into consideration our recent and previous data, as well as results obtained by other authors, is seems possible that the increase of collagen type III expression in the late stage of TM healing contributes to proper scar formation.

Customized Fabrication Approach for Hypertrophic Scar Treatment: 3D Printed Fabric Silicone Composite

Hypertrophic scars (HS) are considered to be the greatest unmet challenge in wound and burn rehabilitation. The most common treatment for HS is pressure therapy, but pressure garments may not be able to exert adequate pressure onto HS due to the complexity of the human body. However, the development of three-dimensional (3D) scanning and direct digital manufacturing technologies has facilitated the customized placement of additively manufactured silicone gel onto fabric as a component of the pressure therapy garment. This study provides an introduction on a novel and customized fabrication approach to treat HS and discusses the mechanical properties of 3D printed fabric reinforced with a silicone composite. For further demonstration of the suggested HS therapy with customized silicone insert, silicone inserts for the finger webs and HS were additively manufactured onto the fabric. Through the pressure evaluation by Pliance X system, it proved that silicone insert increases the pressure exerted to the HS. Moreover, the mechanical properties of the additively manufactured fabric silicone composites were characterized. The findings suggest that as compared with single viscosity print materials, the adhesive force of the additively manufactured silicone and fabric showed a remarkable improvement of 600% when print materials with different viscosities were applied onto elevated fabric.

Customized Fabrication Approach for Hypertrophic Scar Treatment: 3D Printed Fabric Silicone Composite

Hypertrophic scars (HS) are considered to be the greatest unmet challenge in wound and burn rehabilitation. The most common treatment for HS is pressure therapy, but pressure garments may not be able to exert adequate pressure onto HS due to the complexity of the human body. However, the development of three-dimensional (3D) scanning and direct digital manufacturing technologies has facilitated the customized placement of additively manufactured silicone gel onto fabric as a component of the pressure therapy garment. This study provides an introduction on a novel and customized fabrication approach to treat HS and discusses the mechanical properties of 3D printed fabric reinforced with a silicone composite. For further demonstration of the suggested HS therapy with customized silicone insert, silicone inserts for the finger webs and HS were additively manufactured onto the fabric. Through the pressure evaluation by Pliance X system, it proved that silicone insert increases the pressure exerted to the HS. Moreover, the mechanical properties of the additively manufactured fabric silicone composites were characterized. The findings suggest that as compared with single viscosity print materials, the adhesive force of the additively manufactured silicone and fabric showed a remarkable improvement of 600% when print materials with different viscosities were applied onto elevated fabric.

MicroRNA‑486‑5p inhibits the growth of human hypertrophic scar fibroblasts by regulating Smad2 expression

The aim of the current study was to investigate the expression and role of microRNA-486-5p (miR-486-5p) in hypertrophic scar (HS) formation, and to examine the associated mechanisms. First, miR-486-5p expression was detected in HS tissues and human hypertrophic scar fibroblasts (hHSFs) by reverse transcription-quantitative polymerase chain reaction. Target genes of miR-486-5p were predicted using TargetScan and verified by dual-luciferase reporter assays. To investigate the role of miR-486-5p in HS formation, miR-486-5p was overexpressed in hHSFs through transfection with miR-486-5p mimics. MTT, cell apoptosis and cell cycle assays were preformed to investigate the proliferation, cell apoptosis and cell cycle distribution of hHSFs, respectively. Additionally, protein expression was measured by western blot analysis. The results demonstrated that miR-486-5p expression was significantly decreased in HS tissues and cells. Mothers against decapentaplegic homolog (Smad)2 was a target gene of miR-486-5p, and it was negatively regulated by miR-486-5p. It was also found that Smad2 expression was significantly increased in HS tissues and cells. Further analysis indicated that miR-486-5p mimic transfection inhibited the proliferation, induced cell apoptosis and increased G1/S phase arrest in hHSFs. Furthermore, the expression of cyclin-dependent kinase (CDK)2, CDK4 and apoptosis regulator Bcl-2 was repressed, while apoptosis regulator BAX expression was enhanced by miR-486-5p mimic transfection. Notably, the effects of miR-486-5p mimic on hHSFs were significantly eliminated by Smad2 plasmid transfection. Taken together, these results demonstrated that miR-486-5p inhibited the proliferation, induced apoptosis and increased G1/S phase arrest of hHSFs by targeting Smad2. miR-486-5p may be a promising therapeutic target for HS management.

MicroRNA-205-5p regulates extracellular matrix production in hyperplastic scars by targeting Smad2

Hypertrophic scar (HS) formation is the result of poor skin-wound healing. At present, the pathogenesis of HS formation is largely unclear. Micro (miR)RNAs have important effects on a variety of biological and pathological processes. The role of miRNA in HS formation remains largely unclear. The present study aimed to investigate the role of miR-205-5p in HS, and explore the underlying molecular mechanism. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to determine the expression of miR-205-5p in HS. Western blot assay and RT-qPCR were performed to assess the expression of associated proteins and genes, respectively. TargetScan was performed to predict the target gene of miR-205-5p, and the luciferase reporter assay was applied to verify the prediction. The function of miR-205-5p on cell proliferation was detected using Cell Counting Kit-8 assay, and cell apoptosis was detected via flow cytometry. miR-205-5p expression was decreased in HS tissues and human hypertrophic scar fibroblasts (hHSFs). Mothers against decapentaplegic homolog (Smad)2 was significantly increased in HS tissues and HSFs, and it was directly targeted by miR-205-5p. Restoration of miR-205-5p suppressed HSF cell proliferation and induced cell apoptosis. It was also demonstrated that RAC-Alpha Serine/Threonine-Protein Kinase (AKT) phosphorylation and the expression of α-smooth muscle actin, collagen I and collagen III were inhibited by miR-205-5p. In addition, Smad2 weakened the effects of miR-205-5p on HSFs. In conclusion, miR-205-5p exhibited an important role in HS by targeting smad2 and suppressing the AKT pathway. These findings provide a clearer understanding of the mechanism for HS that may be used to develop novel treatments for HS.

Adult Contractures in Burn Injury: A Burn Model System National Database Study

As the overall survival rate for burn injury has improved, increased emphasis is placed on postburn morbidity and the optimization of functional and cosmetic outcomes. One major cause of morbidity and functional deficits is that of joint contractures. The true incidence of postburn contractures and their associated risk factors remains unknown. This study examines the incidence and severity of contractures in a large, multicenter, burn population. The associated risk factors for the development of contractures are determined. Data from the National Institute on Disability and Rehabilitation Research Burn Model System database, for adult burn survivors from 1994 to 2003, were analyzed. Demographic and medical data were collected on each subject. The primary outcome measures included the presence of contractures, number of contractures per patient, and severity of contractures at each of nine locations (shoulder, elbow, hip, knee, ankle, wrist, neck, lumbar spine, and thoracic spine) at time of hospital discharge. Regression analysis was performed to determine predictors of the presence, severity, and numbers of contractures, with P < .05 used for statistical significance. Of the 1865 study patients, 620 (33%) developed at least 1 contracture at hospital discharge. Among those with at least one contracture, the mean is three (3.38) contractures per person. The shoulder was the most frequently contracted joint (23.0%), followed by the elbow (19.9%), wrist (17.3%), ankle (13.6%), and knee (13.4%). Most contractures were mild (47.2%) or moderate (32.9%) in severity. Statistically significant predictors of contracture development were male sex, black race, Hispanic ethnicity, medical problems, neuropathy, TBSA grafted, and TBSA burned. Predictors of the severity of contracture included male sex, black race, medical problems, neuropathy, TBSA grafted, and TBSA burned. Predictors of the number of contractures included male sex, medical problems, flash burn, neuropathy, TBSA burned, and TBSA grafted. Similar to a previous single-center study on postburn contractures, approximately one third of the patients with an eligible burn injury requiring autografting developed a contracture at hospital discharge. It is likely that these contractures develop despite early therapeutic interventions such as positioning and splinting; therefore, the challenge to the burn community remains, to identify new and better prevention strategies.

Pediatric Contractures in Burn Injury: A Burn Model System National Database Study

Joint contractures are a major cause of morbidity and functional deficit. The incidence of postburn contractures and their associated risk factors in the pediatric population has not yet been reported. This study examines the incidence and severity of contractures in a large, multicenter, pediatric burn population. Associated risk factors for the development of contractures are determined. Data from the National Institute on Disability and Rehabilitation Research Burn Model System database, for pediatric (younger than 18 years) burn survivors from 1994 to 2003, were analyzed. Demographic and medical data were collected on each subject. The primary outcome measures included the presence of contractures, number of contractures per patient, and severity of contractures at each of nine locations (shoulder, elbow, hip, knee, ankle, wrist, neck, lumbar, and thoracic) at time of hospital discharge. Regression analysis was performed to determine predictors of the presence, severity, and numbers of contractures, with P < .05 used for statistical significance. Of the 1031 study patients, 237 (23%) developed at least 1 contracture at hospital discharge. Among those with at least one contracture, the mean was three (3.3) contractures per person. The shoulder was the most frequently contracted joint (27.9%), followed by the elbow (17.6%), wrist (14.2%), knee (13.3%), and ankle (11.9%). Most contractures were mild (38.5%) or moderate (36.3%) in severity. The statistically significant predictors of contracture development were age and intensive care unit (ICU) length of stay. The statistically significant predictors of severity of contracture were age, ICU length of stay, presence of amputation, and black race. Predictors of the number of contractures included total age, length of stay, length of ICU stay, presence of amputation, TBSA burned, and TBSA grafted. This is the first study to report the epidemiology of postburn contractures in the pediatric population. Approximately one quarter of children with a major burn injury developed a contracture at hospital discharge, and this could potentially increase as the child grows. Contractures develop despite early therapeutic interventions such as positioning and splinting; therefore, it is essential that we identify novel and more effective prevention strategies.

Cutaneous Scarring: Basic Science, Current Treatments, and Future Directions

Significance: Scarring of the skin from burns, surgery, and injury constitutes a major burden on the healthcare system. Patients affected by major scars, particularly children, suffer from long-term functional and psychological problems. Recent Advances: Scarring in humans is the end result of the wound healing process, which has evolved to rapidly repair injuries. Wound healing and scar formation are well described on the cellular and molecular levels, but truly effective molecular or cell-based antiscarring treatments still do not exist. Recent discoveries have clarified the role of skin stem cells and fibroblasts in the regeneration of injuries and formation of scar. Critical Issues: It will be important to show that new advances in the stem cell and fibroblast biology of scarring can be translated into therapies that prevent and reduce scarring in humans without major side effects. Future Directions: Novel therapies involving the use of purified human cells as well as agents that target specific cells and modulate the immune response to injury are currently undergoing testing. In the basic science realm, researchers continue to refine our understanding of the role that particular cell types play in the development of scar.

History and Advancement of Burn Treatments

Advances in burn care have accelerated within the last 50 years. The principal modalities of and approaches to burn treatment include dressings, antimicrobials, fluid resuscitation, burn wound excision, skin grafting, and use of skin substitutes. This review presents a historical outline of these approaches, their current status, and prospects for the future of burn care.

Scar Management of the Burned Hand

Burn injury can result in hypertrophic scar formation that can lead to debilitating functional deficits and poor aesthetic outcomes. Although nonoperative modalities in the early phase of scar maturation are critical to minimize hypertrophic scar formation, surgical management is often indicated to restore hand function. The essential tenant of operative scar management is release of tension, which can often be achieved through local tissue rearrangement. Laser therapy has emerged as a central pillar of subsequent scar rehabilitation. These treatment tools provide an effective resource for the reconstructive surgeon to treat hypertrophic hand scars.

Biological Principles of Scar and Contracture

Hypertrophic scar and contracture in burn patients is a complex process. Contributing factors include critical injury depth and activation of key cell subpopulations, including deep dermal fibroblasts, myofibroblasts, fibrocytes, and T-helper cells, which cause scarring rather than regeneration. These cells influence each other via cellular profibrotic and antifibrotic signals, which help to determine the outcome. These cells also both modify and interact with extracellular matrix of the wound, ultimately forming hypertrophic scar. Current treatments reduce hypertrophic scar formation or improve remodeling by targeting these pathways and signals.

Sequential Release of Multiple Drugs from Flexible Drug Delivery Films

Sequential release of drugs aligned with the phases of tissue healing could reduce scarring. To achieve this aim, layered film devices comprising cellulose acetate phthalate (CAP) and Pluronic F-127 (Pluronic) were loaded with ketoprofen, quercetin, and pirfenidone. Citrate plasticizers were added to impart flexibility. Release of two or three drugs in sequence over several days was obtained for all multilayered devices tested. Mechanical analysis showed that elongation increased and modulus decreased with increasing plasticizer content. Release profiles can be tailored by order of layers, plasticizer concentration, and drug loaded, making CAP-Pluronic an appealing system for inhibiting scar tissue formation.

Transplanting Human Skin Grafts onto Nude Mice to Model Skin Scars

Hypertrophic scar (HTS) is a common outcome of deep dermal wound healing mainly followed mechanical, chemical, and thermal injuries in the skin. Because of the lack of the most effective prevention and treatment, it is particularly important to establish an ideal dermal animal model for improving the understanding of the pathogenesis and exploring therapeutic approaches of HTS. Compared to other dermal fibrotic animal models in rabbits, red Duroc pigs, guinea pigs, rats, and mice, the approach that uses normal human split-thickness skin grafted onto nude or other immunodeficient mice which develop scars that resemble human HTS offers the advantages of lower cost, easier manipulation, and shorter research period. In this chapter, we will introduce the detailed procedures to create the ideal dermal fibrotic mouse model.

Interleukin-10-mediated regenerative postnatal tissue repair is dependent on regulation of hyaluronan metabolism via fibroblast-specific STAT3 signaling

The cytokine IL-10 has potent antifibrotic effects in models of adult fibrosis, but the mechanisms of action are unclear. Here, we report a novel finding that IL-10 triggers a signal transducer and activator of transcription 3 (STAT3)–dependent signaling pathway that regulates hyaluronan (HA) metabolism and drives adult fibroblasts to synthesize an HA-rich pericellular matrix, which mimics the fetal regenerative wound healing phenotype with reduced fibrosis. By using cre-lox–mediated novel, inducible, fibroblast-, keratinocyte-, and wound-specific STAT3-knockdown postnatal mice—plus syngeneic fibroblast cell-transplant models—we demonstrate that the regenerative effects of IL-10 in postnatal wounds are dependent on HA synthesis and fibroblast-specific STAT3-dependent signaling. The importance of IL-10–induced HA synthesis for regenerative wound healing is demonstrated by inhibition of HA synthesis in a murine wound model by administering 4-methylumbelliferone. Although IL-10 and STAT3 signaling were intact, the antifibrotic repair phenotype that is induced by IL-10 overexpression was abrogated in this model. Our data show a novel role for IL-10 beyond its accepted immune-regulatory mechanism. The opportunity for IL-10 to regulate a fibroblast-specific formation of a regenerative, HA-rich wound extracellular matrix may lead to the development of innovative therapies to attenuate postnatal fibrosis in organ systems or diseases in which dysregulated inflammation and HA intersect.—Balaji, S., Wang, X., King, A., Le, L. D., Bhattacharya, S. S., Moles, C. M., Butte, M. J., de Jesus Perez, V. A., Liechty, K. W., Wight, T. N., Crombleholme, T. M., Bollyky, P. L., Keswani, S. G. Interleukin-10–mediated regenerative postnatal tissue repair is dependent on regulation of hyaluronan metabolism via fibroblast-specific STAT3 signaling.

Combined Effects of Drugs and Plasticizers on the Properties of Drug Delivery Films

Formation of scar tissue may be reduced or prevented if wounds were locally treated with a combination of molecules tuned to the different healing phases, guiding tissue regeneration along a scar free path. To this end, drug delivery devices made of cellulose acetate phthalate and Pluronic F-127 were loaded with either quercetin or pirfenidone and plasticized with either triethyl citrate (TEC) or tributyl citrate (TBC). Quercetin inhibits oxidative stress, and pirfenidone has been shown to reduce production of pro-inflammatory and fibrogenic molecules. The combined effects of drug and plasticizer on erosion, release, and mechanical properties of the drug delivery films were investigated. TEC-plasticized films containing quercetin released drug at a slower rate than did TBC films. Pirfenidone-loaded films released drug at a faster rate than erosion occurred for both types of plasticizers. Higher plasticizer contents of both TEC and TBC increased the elongation and decreased the elastic modulus. In contrast, increased pirfenidone loading in both TEC and TBC films resulted in a significantly higher modulus, an anti-plasticizer effect. Adding pirfenidone significantly decreased elongation for all film types, but quercetin-loaded samples had significantly greater elongation with increasing drug content. Films containing quercetin elongated more than did pirfenidone-loaded films. Quercetin is over 1.5 times larger than pirfenidone, has water solubility over 12 times lower, and has 6 times more bonding sites than pirfenidone. These differences affected how the two drugs interacted with cellulose acetate phthalate and Pluronic F-127 and thereby determined polymer properties. Drug release, erosion, and mechanical properties of association polymer films can be tailored by the characteristics of the drugs and plasticizers included in the system.

The molecular basis of hypertrophic scars

Hypertrophic scars (HTS) are caused by dermal injuries such as trauma and burns to the deep dermis, which are red, raised, itchy and painful. They can cause cosmetic disfigurement or contractures if craniofacial areas or mobile region of the skin are affected. Abnormal wound healing with more extracellular matrix deposition than degradation will result in HTS formation. This review will introduce the physiology of wound healing, dermal HTS formation, treatment and difference with keloids in the skin, and it also review the current advance of molecular basis of HTS including the involvement of cytokines, growth factors, and macrophages via chemokine pathway, to bring insights for future prevention and treatment of HTS.

The therapeutic potential of a C-X-C chemokine receptor type 4 (CXCR-4) antagonist on hypertrophic scarring in vivo

Effective prevention and treatment of hypertrophic scars (HTSs), a dermal form of fibrosis that frequently occurs following thermal injury to deep dermis, are unsolved significant clinical problems. Previously, we have found that stromal cell-derived factor 1/CXCR4 signaling is up-regulated during wound healing in burn patients and HTS tissue after thermal injury. We hypothesize that blood-borne mononuclear cells are recruited into wound sites after burn injury through the chemokine pathway of stromal cell-derived factor 1 and its receptor CXCR4. Deep dermal injuries to the skin are often accompanied by prolonged inflammation, which leads to chemotaxis of mononuclear cells into the wounds by chemokine signaling where fibroblast activation occurs and ultimately HTS are formed. Blocking mononuclear cell recruitment and fibroblast activation, CXCR4 antagonism is expected to reduce or minimize scar formation. In this study, the inhibitory effect of CXCR4 antagonist CTCE-9908 on dermal fibrosis was determined in vivo using a human HTS-like nude mouse model, in which split-thickness human skin is transplanted into full-thickness dorsal excisional wounds in athymic mice, where these wounds subsequently develop fibrotic scars that resemble human HTS as previously described. CTCE-9908 significantly attenuated scar formation and contraction, reduced the accumulation of macrophages and myofibroblasts, enhanced the remodeling of collagen fibers, and down-regulated the gene and protein expression of fibrotic growth factors in the human skin tissues. These findings support the potential therapeutic value of CXCR4 antagonist in dermal fibrosis and possibly other fibroproliferative disorders.

MicroRNA 181b regulates decorin production by dermal fibroblasts and may be a potential therapy for hypertrophic scar

Hypertrophic scarring is a frequent fibroproliferative complication following deep dermal burns leading to impaired function and lifelong disfigurement. Decorin reduces fibrosis and induces regeneration in many tissues, and is significantly downregulated in hypertrophic scar and normal deep dermal fibroblasts. It was hypothesized that microRNAs in these fibroblasts downregulate decorin and blocking them would increase decorin and may prevent hypertrophic scarring. Lower decorin levels were found in hypertrophic scar as compared to normal skin, and in deep as compared to superficial dermis. A decorin 3' un-translated region reporter assay demonstrated microRNA decreased decorin in deep dermal fibroblasts, and microRNA screening predicted miR- 24, 181b, 421, 526b, or 543 as candidates. After finding increased levels of mir-181b in deep dermal fibroblasts, it was demonstrated that TGF-β1 stimulation decreased miR-24 but increased miR-181b and that hypertrophic scar and deep dermis contained increased levels of miR-181b. By blocking miR-181b with an antagomiR, it was possible to increase decorin protein expression in dermal fibroblasts. This suggests miR-181b is involved in the differential expression of decorin in skin and wound healing. Furthermore, blocking miR-181b reversed TGF-β1 induced decorin downregulation and myofibroblast differentiation in hypertrophic scar fibroblasts, suggesting a potential therapy for hypertrophic scar.

Biology and principles of scar management and burn reconstruction

Hypertrophic scarring is extremely common and is the source of most morbidity related to burns. The biology of hypertrophic healing is complex and poorly understood. Multiple host and injury factors contribute, but protracted healing of partial thickness injury is a common theme. Hypertrophic scarring and heterotopic ossification may share some basic causes involving marrow-derived cells. Several traditional clinical interventions exist to modify hypertrophic scar. All have limited efficacy. Laser interventions for scar modification show promise, but as yet do not provide a definitive solution. Their efficacy is only seen when used as part of a multimodality scar management program.

Efficacy and Tolerability of a New Pharmaceutical Form of Betamethasone Valerate in the Prevention of Hypertrophic Scars following Anterior Trunk Plastic Surgery: A Preliminary Exploratory Study

Hypertrophic scars are fibroproliferative diseases of the skin. Many treatment options are now available, but none is completely effective. The primary objective of this study was to compare the efficacy of a betamethasone valerate (BMV) 2.25 mg plaster versus no treatment in the prevention of hypertrophic scars after anterior trunk plastic surgery. An exploratory, open, prospective, controlled study was carried out on 16 consecutive patients with postoperative wounds. A 12-week daily treatment was initiated after wounds cicatrisation. The effect of a daily application of the plaster was compared to no treatment by dividing the wound into 2–4 parts. The wound evaluation was performed during the treatment period at 2, 4, 8 and 12 weeks, and 6 months after the end of the treatment. A total of 60 wounds was evaluated. Pain and itching improved in both groups after 12 weeks. However, only the wounds treated with BMV plaster showed a significantly greater and more rapid improvement as compared with the non-treated wounds after 4 and 8 weeks of treatment in all the evaluated parameters (p<0.0001). The efficacy and tolerability of BMV plaster in the prevention of hypertrophic scar development is promising.

A collagen-based scaffold delivering exogenous microrna-29B to modulate extracellular matrix remodeling

Directing appropriate extracellular matrix remodeling is a key aim of regenerative medicine strategies. Thus, antifibrotic interfering RNA (RNAi) therapy with exogenous microRNA (miR)-29B was proposed as a method to modulate extracellular matrix remodeling following cutaneous injury. It was hypothesized that delivery of miR-29B from a collagen scaffold will efficiently modulate the extracellular matrix remodeling response and reduce maladaptive remodeling such as aggressive deposition of collagen type I after injury. The release of RNA from the scaffold was assessed and its ability to silence collagen type I and collagen type III expression was evaluated in vitro. When primary fibroblasts were cultured with scaffolds doped with miR-29B, reduced levels of collagen type I and collagen type III mRNA expression were observed for up to 2 weeks of culture. When the scaffolds were applied to full thickness wounds in vivo, reduced wound contraction, improved collagen type III/I ratios and a significantly higher matrix metalloproteinase (MMP)-8: tissue inhibitor of metalloproteinase (TIMP)-1 ratio were detected when the scaffolds were functionalized with miR-29B. Furthermore, these effects were significantly influenced by the dose of miR-29B in the collagen scaffold (0.5 versus 5 μg). This study shows a potential of combining exogenous miRs with collagen scaffolds to improve extracellular matrix remodeling following injury.

The molecular mechanism of hypertrophic scar

Hypertrophic scar (HTS) is a dermal form of fibroproliferative disorder which often develops after thermal or traumatic injury to the deep regions of the skin and is characterized by excessive deposition and alterations in morphology of collagen and other extracellular matrix (ECM) proteins. HTS are cosmetically disfiguring and can cause functional problems that often recur despite surgical attempts to remove or improve the scars. In this review, the roles of various fibrotic and anti-fibrotic molecules are discussed in order to improve our understanding of the molecular mechanism of the pathogenesis of HTS. These molecules include growth factors, cytokines, ECM molecules, and proteolytic enzymes. By exploring the mechanisms of this form of dermal fibrosis, we seek to provide some insight into this form of dermal fibrosis that may allow clinicians to improve treatment and prevention in the future.

The role of the myofibroblast in tumor stroma remodeling

Since its first description in wound granulation tissue, the myofibroblast has been recognized to be a key actor in the epithelial-mesenchymal cross-talk that plays a crucial role in many physiological and pathological situations, such as regulation of prostate development, ventilation-perfusion in lung alveoli or organ fibrosis. The presence of myofibroblasts in the stroma reaction to epithelial tumors is well established and many data are accumulating which suggest that the stroma compartment is an active participant in tumor onset and/or evolution. In this review we summarize the evidence in favor of this concept, the main mechanisms that regulate myofibroblast differentiation and function, as well as the biophysical and biochemical factors possibly involved in epithelial-stroma interactions, using liver carcinoma as main model, in view of achieving a better understanding of tumor progression mechanisms and of tools directed toward stroma as eventual therapeutic target.

Implantation of allogenic synovial stem cells promotes meniscal regeneration in a rabbit meniscal defect model

BACKGROUND

Indications for surgical meniscal repair are limited, and failure rates remain high. Thus, new ways to augment repair and stimulate meniscal regeneration are needed. Mesenchymal stem cells are multipotent cells present in mature individuals and accessible from peripheral connective tissue sites, including synovium. The purpose of this study was to quantitatively evaluate the effect of implantation of synovial tissue-derived mesenchymal stem cells on meniscal regeneration in a rabbit model of partial meniscectomy.

METHODS

Synovial mesenchymal stem cells were harvested from the knee of one New Zealand White rabbit, expanded in culture, and labeled with a fluorescent marker. A reproducible 1.5-mm cylindrical defect was created in the avascular portion of the anterior horn of the medial meniscus bilaterally in fifteen additional rabbits. Allogenic synovial mesenchymal stem cells suspended in phosphate-buffered saline solution were implanted into the right knees, and phosphate-buffered saline solution alone was placed in the left knees. Meniscal regeneration was evaluated histologically at four, twelve, and twenty-four weeks for (1) quantity and (2) quality (with use of an established three-component scoring system). A similar procedure was performed in four additional rabbits with use of green fluorescent protein-positive synovial mesenchymal stem cells for the purpose of tracking progeny following implantation.

RESULTS

The quantity of regenerated tissue in the group that had implantation of synovial mesenchymal stem cells was greater at all end points, reaching significance at four and twelve weeks (p < 0.05). Tissue quality scores were also superior in knees treated with mesenchymal stem cells compared with controls at all end points, achieving significance at twelve and twenty-four weeks (3.8 versus 2.8 at four weeks [p = 0.29], 5.7 versus 1.7 at twelve weeks [p = 0.008], and 6.0 versus 3.9 at twenty-four weeks [p = 0.021]). Implanted cells adhered to meniscal defects and were observed in the regenerated tissue, where they differentiated into type-I and II collagen-expressing cells, at up to twenty-four weeks.

CONCLUSIONS

Synovial mesenchymal stem cells adhere to sites of meniscal injury, differentiate into cells resembling meniscal fibrochondrocytes, and enhance both quality and quantity of meniscal regeneration.

Scar contractures of the hand

This article discusses scar contracture of the hand. It contains a brief outline of the anatomy of the hand and upper extremities and the types of injuries involved. Hand reconstruction, including examination, nonoperative treatment, surgery, excision and skin grafting, flaps, postoperative management, and complications, are covered.