The mechanism of skin graft contraction: An update on current research and potential future therapies

An approach to achieve tension-free closure and mitigate recurrence in the management of recurrent cervical keloids

Keloid is a burdensome condition that negatively affects patient's quality of life. It is influenced by a spectrum of risk factors, including tension. We propose an approach to address the tension-free closure and optimize surgical outcomes in neck keloid. A retrospective review of neck keloid patients who underwent surgical treatment between 2014 and 2022 was performed. Five patients underwent surgical interventions. Two patients had sufficient and three had insufficient tissue redundancy. The former underwent keloid excision with tension-free closure. The latter underwent keloid excision with full thickness skin graft for tension-free closure. One patient required re-excision with free flap coverage. All patients received postoperative low dose radiation. All patients were satisfied with the results and there were no signs of keloid recurrence during the follow-up period. Tension during closure following keloid excision is a modifiable risk factor. An appropriate algorithm providing tension-free closure can minimize the recurrence.

Management of Scar Contractures of the Hand-Our Therapeutic Strategy and Challenges

The essence of treating scar contractures lies in covering the skin deficit after releasing the contractures, typically using flaps or skin grafts. However, the specific characteristics of scar contractures, such as their location, shape, and size, vary among patients, which makes surgical planning challenging. To achieve excellent outcomes in the treatment of scar contractures, we have developed a dimensional classification system for these contractures. This system categorizes them into four types: type 1 (superficial linear), type 2-d (deep linear), type 2-s (planar scar contractures confined to the superficial layer), and type 3 (planar scar contractures that reach the deep layer, i.e., three-dimensional scar contractures). Additionally, three factors should be considered when determining surgical approaches: the size of the defect, the availability of healthy skin around the defect, and the blood circulation in the defect bed. Type 1 and type 2-d are linear scars; thus, the scar is excised and sutured in a straight line, and the contracture is released using z-plasty or its modified methods. For type 2-s, after releasing the scar contracture band, local flaps are indicated for small defects, pedicled perforator flaps for medium defects, and free flaps and distant flaps for large defects. Type 2-s has good blood circulation in the defect bed, so full-thickness skin grafting is also a suitable option regardless of the defect's size. In type 3, releasing the deep scar contracture will expose important structures with poor blood circulation, such as tendons, joints, and bones. Thus, a surgical plan using flaps, rather than skin grafts, is recommended. A severity classification and treatment strategy for scar contractures have not yet been established. By objectively classifying and quantifying scar contractures, we believe that better treatment outcomes can be achieved.

Radial matrix constraint influences tissue contraction and promotes maturation of bi-layered skin equivalents

Human skin equivalents (HSEs) serve as important tools for mechanistic studies with human skin cells, drug discovery, pre-clinical applications in the field of tissue engineering and for skin transplantation on skin defects. Besides the cellular and extracellular matrix (ECM) components used for HSEs, physical constraints applied on the scaffold during HSEs maturation influence tissue organization, functionality, and homogeneity. In this study, we introduce a 3D-printed culture insert that exposes bi-layered HSEs to a static radial constraint through matrix adhesion. We examine the effect of various diameters of the ring-shaped culture insert on the HSE's characteristics and compare them to state-of-the-art unconstrained and planar constrained HSEs. We show that radial matrix constraint of HSEs regulates tissue contraction, promotes fibroblast and matrix organization that is similar to human skin in vivo and improves keratinocyte differentiation, epidermal stratification, and basement membrane formation depending on the culture insert diameter. Together, these data demonstrate that the degree of HSE's contraction is an important design consideration in skin tissue engineering. Therefore, this study can help to mimic various in vivo skin conditions and to increase the control of relevant tissue properties.

Effect of hydroalcoholic extract of Trigonella foenum-graecum leaves on wound healing in type 1 diabetic rats

Diabetes describes a group of metabolic disorders characterised by increased blood glucose concentration. People living with diabetes have a higher risk of morbidity and mortality than the general population. In 2015 it was estimated that there were 415 million (uncertainty interval: 340-536 million) people with diabetes aged 20-79 years, and 5.0 million deaths attributable to diabetes. When diabetic patients develop an ulcer, they become at high risk for major complications, including infection and amputation. The pathophysiologic relationship between diabetes and impaired healing is complex. Vascular, neuropathic, immune function, and biochemical abnormalities each contribute to the altered tissue repair. The use of herbal medicine has increased and attracted the attention of many researchers all over the world. In this study, we have evaluated the effect of 500mg/kg hydroalcoholic extract of Trigonella foenum-graecum leaves (TFG-E) on wound healing in diabetic rats using a full-thickness cutaneous incisional wound model. Wounds of treated animals showed better tensiometric indices, accelerated wound contraction, faster re-epithelialisation, improved neovascularisation, better modulation of fibroblasts and macrophage presence in the wound bed and moderate collagen formation.

Establishment and validation of a nomogram to predict the neck contracture after skin grafting in burn patients: A multicentre cohort study

Cervical burn contracture is one of the burn contractures with the highest incidence and severity, and there is no effective method to predict the risk of neck contracture. This study aimed to investigate the effect of combined cervicothoracic skin grafting on the risk of neck contracture in burn patients and to develop a nomogram to predict the risk of neck contracture after skin grafting in burn patients. Data from 212 patients with burns who underwent neck skin grafting were collected from three hospitals, and the patients were randomly divided into training and validation sets. Independent predictors were identified through univariate and multivariate logistic regression analyses and incorporated into a prognostic nomogram. Its performance was assessed using the receiver operating characteristic area under the curve, calibration curve, and decision curve analysis. Burn depth, combined cervicothoracic skin grafting, graft thickness, and neck graft size were significantly associated with neck contractures. In the training cohort, the nomogram had an area under the curve of 0.894. The calibration curve and decision curve analysis indicated good clinical applicability of the nomogram. The results were tested using a validation dataset. Combined cervicothoracic skin grafting is an independent risk factor for neck contracture. Our nomogram demonstrated excellent performance in predicting neck contracture risk.

The Immediate Contraction of the Expanded Forehead Flap

INTRODUCTION

Flaps contract immediately after harvest, which added difficulty to flap design. This study aims to investigate the immediate contraction rate of the expanded forehead flap used in nasal reconstruction.

METHODS

Patients undergoing nasal reconstruction with expanded forehead flaps from September 2021 to January 2023 were included. Objective measurements of the pedicle width, maximum width, maximum length, and flap size of the expanded forehead flap before and after harvest were conducted.

RESULTS

Fourteen patients, including 9 males and 5 females, were included. The average expansion period was 4.6 months, and the mean injection volume was 658.6 ml. The average retraction rate of pedicle width, maximum width, maximum length, and size of the flap after harvest were 16.15%, 30.26%, 26.86%, and 50.89%, respectively.

CONCLUSION

This study presents the contraction rate of the expanded forehead flap used for nasal reconstruction. The data from the measurement will help surgeons to design the expanded forehead flap.

LEVEL OF EVIDENCE

Level-Level IV.

A Histological and Clinical Study of MatriDerm® Use in Burn Reconstruction

Dermal substitutes are well established in the reconstructive ladder. MatriDerm® (Dr. Otto Suwelack Skin & Health Care AG, Billerbeck, Germany) is a single-layer dermal substitute composed of a bovine collagen (type I, III, and V) and elastin hydrolysate, that allows for immediate split-thickness skin grafting (SSG). The aim of this study was to histologically characterize the integration of MatriDerm® when used during burns surgery reconstruction. Eight subjects with nine burn scars and one acute burn wound underwent reconstruction with MatriDerm® and an immediate SSG. MatriDerm® integration and skin graft take were assessed with serial biopsies performed at weeks 1, 2, 3, and 4 and months 2, 3, 6, 9, and 12. Biopsies were assessed with standard special stains and immunohistochemistry, and representative slides were imaged with a transmission electron microscope. Patient satisfaction and clinical scar outcome were assessed with the Vancouver Scar Scale and a patient questionnaire. Histological analysis showed similar stages of wound healing as shown in other dermal templates but on a different timescale. There is early evidence of vascularization and an inflammatory infiltrate in the first 2 weeks. MatriDerm® is resorbed earlier than other dermal substitutes, with evidence of resorption at week 3, to be completely replaced by a neodermis at 2 months. The use of MatriDerm® in reconstruction with immediate skin grafting is supported histologically with early evidence of vascularization to support an epidermal autograft. Future histological studies may help further characterize the ideal dermal substitute.

Epidemiology and Predictors for Cervical Burn Scar Contractures: A Multicenter Cohort Study

Cervical burn scar contracture (BSC) affects many important neck functions and the patients' quality of life. However, it remains unclear which patients have a higher risk of neck BSCs. This study aimed to describe the epidemiology and identify the independent risks of cervical BSC formation and severity. Clinical and demographic data of 106 patients with burn scars were retrospectively collated and analyzed from 3 different Chinese hospitals between December 2016 and December 2020. Both univariate and multivariate logistic regression analyses were performed to identify the independent risks for BSC formation and severity at 12 months postburn. Lateral flexion was the most common plane of motion (POM) limited by contractures (29.4%), whereas the POM most commonly limited by severe contractures was the extension (24.6%). Most patients with contractures had those in 3 to 4 POMs (72.1%). Neck skin grafting was an independent risk factor for BSC formation, and cervical and cervicothoracic skin grafting were independent risk factors for BSC severity. These results may help to identify high-risk patients with contractures in the early stages of burns to carry out individualized early prevention and treatment.

Immune cells and associated molecular markers in dermal fibrosis with focus on raised cutaneous scars

Raised dermal scars including hypertrophic, and keloid scars as well as scalp-associated fibrosing Folliculitis Keloidalis Nuchae (FKN) are a group of fibrotic raised dermal lesions that mostly occur following cutaneous injury. They are characterized by increased extracellular matrix (ECM) deposition, primarily excessive collagen type 1 production by hyperproliferative fibroblasts. The extent of ECM deposition is thought to be proportional to the severity of local skin inflammation leading to excessive fibrosis of the dermis. Due to a lack of suitable study models, therapy for raised dermal scars remains ill-defined. Immune cells and their associated markers have been strongly associated with dermal fibrosis. Therefore, modulation of the immune system and use of anti-inflammatory cytokines are of potential interest in the management of dermal fibrosis. In this review, we will discuss the importance of immune factors in the pathogenesis of raised dermal scarring. The aim here is to provide an up-to-date comprehensive review of the literature, from PubMed, Scopus, and other relevant search engines in order to describe the known immunological factors associated with raised dermal scarring. The importance of immune cells including mast cells, macrophages, lymphocytes, and relevant molecules such as cytokines, chemokines, and growth factors, antibodies, transcription factors, and other immune-associated molecules as well as tissue lymphoid aggregates identified within raised dermal scars will be presented. A growing body of evidence points to a shift from proinflammatory Th1 response to regulatory/anti-inflammatory Th2 response being associated with the development of fibrogenesis in raised dermal scarring. In summary, a better understanding of immune cells and associated molecular markers in dermal fibrosis will likely enable future development of potential immune-modulated therapeutic, diagnostic, and theranostic targets in raised dermal scarring.

Model to Inhibit Contraction in Third-Degree Burns Employing Split-Thickness Skin Graft and Administered Bone Marrow-Derived Stem Cells

Third-degree burns typically result in pronounced scarring and contraction in superficial and deep tissues. Established techniques such as debridement and grafting provide benefit in the acute phase of burn therapy, nevertheless, scar and contraction remain a challenge in deep burns management. Our ambition is to evaluate the effectiveness of novel cell-based therapies, which can be implemented into the standard of care debridement and grafting procedures. Twenty-seven third-degree burn wounds were created on the dorsal area of Red Duroc pig. After 72 h, burns are surgically debrided using a Weck knife. Split-thickness skin grafts (STSGs) were then taken after debridement and placed on burn scars combined with bone marrow stem cells (BM-MSCs). Biopsy samples were taken on days 17, 21, and 45 posttreatment for evaluation. Histological analysis revealed that untreated control scars at 17 days are more raised than burns treated with STSGs alone and/or STSGs with BM-MSCs. Wounds treated with skin grafts plus BM-MSCs appeared thinner and longer, indicative of reduced contraction. qPCR revealed some elevation of α-SMA expression at day 21 and Collagen Iα2 in cells derived from wounds treated with skin grafts alone compared to wounds treated with STSGs + BM-MSCs. We observed a reduction level of TGFβ-1 expression at days 17, 21, and 45 in cells derived from wounds treated compared to controls. These results, where the combined use of stem cells and skin grafts stimulate healing and reduce contraction following third-degree burn injury, have a potential as a novel therapy in the clinic.

Donor Age and Time in Culture Affect Dermal Fibroblast Contraction in an In Vitro Hydrogel Model

Current cellular hydrogel-based skin grafts composed of human dermal fibroblasts and a hydrogel scaffold tend to minimize contraction of full-thickness skin wounds and support skin regeneration. However, there has been no comparison between the sources of the dermal fibroblast used. Products using human adult or neonatal foreskin dermal fibroblasts are often expanded in vitro and used after multiple passages without a clear understanding of the effects of this initial production step on the quality and reproducibility of the cellular behavior. Based on the known effects of 2D tissue culture expansion on cellular proliferation and gene expression, we hypothesized that differences in donor age and time in culture may influence cellular properties and contractile behavior in a fibroblast-populated collagen matrix. Using porcine skin as a model based on its similarity to human skin in structure and wound healing properties, we isolated porcine dermal fibroblasts of three different donor ages for use in a 2D proliferation assay and in a 3D cell-populated collagen matrix contractility assay. In 2D cell culture, doubling time remained relatively consistent between all age groups from passage 1 to 6. In the contractility assays, fetal and neonatal groups contracted faster and generated more contractile force than the adult group at passage 1 in vitro. However, after five passages in culture, there was no difference in contractility between ages. These results show how cellular responses in a hydrogel scaffold differ based on donor age and time in culture in vitro, and suggest that consistency in the cellular component of bioengineered skin products could be beneficial in the biomanufacturing of consistent, reliable skin grafts and graft in vivo models. Future research and therapies using bioengineered skin grafts should consider how results may vary based on donor age and time in culture before seeding. Impact statement Little is known about the impact of donor cell age and time in culture on the contraction of cellular, hydrogel-based skin grafts. These results show how cellular phenotypes of porcine fibroblasts differ based on donor age and time in culture. This information is beneficial when addressing important inconsistencies in biomanufacturing of bioengineered skin grafts and in vitro models. These findings are relevant to research and therapies using bioengineered skin graft models and the results can be used to increase reproducibility and consistency during the production of bioengineered skin constructs. The information from this study can be extrapolated to future in vivo studies using human dermal fibroblasts in an in vivo model to help determine the best donor age and time in culture for optimal wound healing outcomes or more reproducible in vitro testing constructs.

Skin grafting treatment of adolescent lower limb avulsion injury

Background

Under the influence of various factors, the number of lower extremity avulsion injuries in adolescents is increasing year by year. The main modality of treatment is skin grafting. There are many types of skin grafting. Although many studies on skin grafting after avulsion injuries have been published in the past few decades, there are differences in the treatment options for adolescents with post avulsion injuries.

Main body

Thorough debridement and appropriate skin grafts are essential for the surgical management of avulsion injuries for optimal prognosis. In the acquisition of grafts, progress has been made in equipment for how to obtain different depths of skin. The severity of the avulsion injury varies among patients on admission, and therefore the manner and type of skin grafting will vary. Especially in adolescents, graft survival and functional recovery are of great concern to both patients and physicians. Therefore, many efforts have been made to improve survival rate and activity.

Conclusion

This review summarizes the principles of treatment of avulsion injuries, the historical development of skin grafts, and the selection of skin grafts, hoping to be helpful for future research.

Objective Skin Quality Assessment after Reconstructive Procedures for Facial Skin Defects

Local random skin flaps and skin grafts are everyday surgical techniques used to reconstruct skin defects. Although their clinical advantages and disadvantages are well known, there are still uncertainties with respect to their long-term results. Hence, the aim of this study was to evaluate outcomes more than one-year post operatively using objective measurement devices. The study included 31 facial defects reconstructed with local random flap, 30 facial defects reconstructed with split-thickness skin grafts (STSGs) and 30 facial defects reconstructed with full-thickness skin grafts (FTSGs). Skin quality was objectively evaluated using MP6 noninvasive probes (Courage + Khazaka GmbH, Cologne, Germany), which measure melanin count, erythema, hydration, sebum, friction and transepidermal water loss. The results showed that there were no significant differences in melanin count, erythema, hydration, sebum level, friction value and transepidermal water loss (TEWL) between the site reconstructed with random local flaps and the same site on the healthy contralateral side of the face. However, both FTSGs and STSGs showed significantly higher levels in terms of TEWL and erythema, whereas the levels of hydration, sebum and friction were significantly lower compared to the healthy contralateral side. Moreover, STSGs resulted in a significant difference in melanin count. These findings imply that the complex pathophysiology of the wound-healing process possibly results in better skin-quality outcomes for random local flaps than skin autografts. Consequently, this suggests that random local flaps should be implemented whenever possible for the reconstruction of facial region defects.

Biomaterials-Based Regenerative Strategies for Skin Tissue Wound Healing

Skin tissue wound healing proceeds through four major stages, including hematoma formation, inflammation, and neo-tissue formation, and culminates with tissue remodeling. These four steps significantly overlap with each other and are aided by various factors such as cells, cytokines (both anti- and pro-inflammatory), and growth factors that aid in the neo-tissue formation. In all these stages, advanced biomaterials provide several functional advantages, such as removing wound exudates, providing cover, transporting oxygen to the wound site, and preventing infection from microbes. In addition, advanced biomaterials serve as vehicles to carry proteins/drug molecules/growth factors and/or antimicrobial agents to the target wound site. In this review, we report recent advancements in biomaterials-based regenerative strategies that augment the skin tissue wound healing process. In conjunction with other medical sciences, designing nanoengineered biomaterials is gaining significant attention for providing numerous functionalities to trigger wound repair. In this regard, we highlight the advent of nanomaterial-based constructs for wound healing, especially those that are being evaluated in clinical settings. Herein, we also emphasize the competence and versatility of the three-dimensional (3D) bioprinting technique for advanced wound management. Finally, we discuss the challenges and clinical perspective of various biomaterial-based wound dressings, along with prospective future directions. With regenerative strategies that utilize a cocktail of cell sources, antimicrobial agents, drugs, and/or growth factors, it is expected that significant patient-specific strategies will be developed in the near future, resulting in complete wound healing with no scar tissue formation.

Efficacy and safety of a dual-scan protocol for carbon dioxide laser in the treatment of split-thickness skin graft contraction in a red Duroc pig model

BACKGROUND

Fractional CO₂ laser plays an important role in scar management post split-thickness skin graft by loosening the graft contracture and restoring the smoothness of the surface. However, the optimal treatment protocol remains unknown. This study applied a dual-scan protocol to achieve both releasing and ablation of contracted skin graft. We comprehensively describe this treatment method and compare the efficacy and safety between this dual-scan method and the conventional mono-scan mode.

METHODS

A hypercontracted scar model after split-thickness skin grafting in red Duroc pigs was established. All scars meeting the inclusion criteria were randomly divided into four groups: high fluence-low density (HF-LD), low fluence-high density (LF-HD), combined group and control group. The energy per unit area was similar in the HF-LD and LF-HD groups. Two laser interventions were performed at a 6-week interval. The efficacy of the treatment was evaluated by objective measures of scar area, release rate, elasticity, thickness and flatness, while the safety was evaluated based on adverse reactions and melanin index. Collagen structure was observed histologically. The animals were followed up for a maximum of 126 days after modeling.

RESULTS

A total of 28 contracted scars were included, 7 in each group. At 18 weeks postoperatively, the HF-LD and the combined groups showed significantly increased scar release rate (p = 0.000) and elasticity (p = 0.036) and decreased type I/III collagen ratio (p = 0.002) compared with the control and LF-HD groups. In terms of flatness, the combined group was significantly better than the HF-LD group for elevations <1 mm (p = 0.019). No significant skin side effects, pigmentation or scar thickness changes were observed at 18 weeks.

CONCLUSIONS

Dual-scan protocol could achieve superficial ablation and deep release of contracted split-thickness skin graft in a single treatment, with similar contraction release and texture improvement compared to a single deep scan. Its main advantage is to restore a smoother scar appearance. Adequate laser penetration was necessary for the release of contracted scars.

A Comparative Assessment of Scars Resulting From Skin Grafts in Facial Defects

PURPOSE

The authors compared facial scars after split-thickness skin grafts (STSGs) performed with a dermal substitute or after full-thickness skin grafts (FTSGs) in facial defect.

MATERIALS AND METHODS

The medical records of patients who had undergone FTSG or STSG with dermal substitute after skin cancer surgery between March 2016 and December 2018 were retrospectively reviewed. The scars resulting from skin grafts were assessed using the patient and observer scar assessment scales (PSAS and OSAS) in our clinic after a minimum of 6 months postoperatively.

RESULTS

Of the 50 study subjects, 35 patients (FTSG group) received FTSG only and 15 patients (STSG group) received STSG with the dermal substitute. The total scores of PSAS and OSAS were significantly lower in the FTSG group and it is suggested that both patients and observers thought that better scar outcomes were achieved when FTSGs were used. However, for defects smaller than 1.8 cm2 and defects located in the periorbital area, there was no statistically significant difference in the scores of PSAS and OSAS in the 2 groups. Interestingly, for defects located in the periorbital area, although there was no significant difference, PSAS and OSAS scores were lower in the STSG group than in the FTSG group. In other word, scar outcomes in the STSG group were better.

CONCLUSIONS

Although there was no significant difference, unlike what we usually know, our result shows that STSG with dermal substitute tended to produce comparable or rather better results than FTSG under some conditions.

Engineered Pullulan-Collagen-Gold Nano Composite Improves Mesenchymal Stem Cells Neural Differentiation and Inflammatory Regulation

Tissue repair engineering supported by nanoparticles and stem cells has been demonstrated as being an efficient strategy for promoting the healing potential during the regeneration of damaged tissues. In the current study, we prepared various nanomaterials including pure Pul, pure Col, Pul–Col, Pul–Au, Pul–Col–Au, and Col–Au to investigate their physicochemical properties, biocompatibility, biological functions, differentiation capacities, and anti-inflammatory abilities through in vitro and in vivo assessments. The physicochemical properties were characterized by SEM, DLS assay, contact angle measurements, UV-Vis spectra, FTIR spectra, SERS, and XPS analysis. The biocompatibility results demonstrated Pul–Col–Au enhanced cell viability, promoted anti-oxidative ability for MSCs and HSFs, and inhibited monocyte and platelet activation. Pul–Col–Au also induced the lowest cell apoptosis and facilitated the MMP activities. Moreover, we evaluated the efficacy of Pul–Col–Au in the enhancement of neuronal differentiation capacities for MSCs. Our animal models elucidated better biocompatibility, as well as the promotion of endothelialization after implanting Pul–Col–Au for a period of one month. The above evidence indicates the excellent biocompatibility, enhancement of neuronal differentiation, and anti-inflammatory capacities, suggesting that the combination of pullulan, collagen, and Au nanoparticles can be potential nanocomposites for neuronal repair, as well as skin tissue regeneration in any further clinical treatments.

Management of full-thickness skin grafts

Full-thickness skin grafts are a commonly used reconstructive method following Mohs micrographic surgery. The literature varies on the most appropriate methods of suturing and securing grafts as well as best practices to dress the graft postoperatively. Our objective was to review various approaches to management of full-thickness skin grafts, including suturing the graft, securing the graft, and topical emollient use on the graft postoperatively. It was found that absorbable sutures, plain gut, provide preferable outcomes with full-thickness skin grafts. The tie-over bolster is the most-used method for securing skin grafts after placement, although several other methods have demonstrated efficacy, including the polyurethane foam, sandwich, and quilting suture methods. While various topical emollients are used in the immediate postoperative period, plain white petrolatum is the least likely to form allergic contact dermatitis.

Mechanobiological wound model for improved design and evaluation of collagen dermal replacement scaffolds

Skin wounds are among the most common and costly medical problems experienced. Despite the myriad of treatment options, such wounds continue to lead to displeasing cosmetic outcomes and also carry a high burden of loss-of-function, scarring, contraction, or nonhealing. As a result, the need exists for new therapeutic options that rapidly and reliably restore skin cosmesis and function. Here we present a new mechanobiological computational model to further the design and evaluation of next-generation regenerative dermal scaffolds fabricated from polymerizable collagen. A Bayesian framework, along with microstructure and mechanical property data from engineered dermal scaffolds and autograft skin, were used to calibrate constitutive models for collagen density, fiber alignment and dispersion, and stiffness. A chemo-bio-mechanical finite element model including collagen, cells, and representative cytokine signaling was adapted to simulate no-fill, dermal scaffold, and autograft skin outcomes observed in a preclinical animal model of full-thickness skin wounds, with a focus on permanent contraction, collagen realignment, and cellularization. Finite element model simulations demonstrated wound cellularization and contraction behavior that was similar to that observed experimentally. A sensitivity analysis suggested collagen fiber stiffness and density are important scaffold design features for predictably controlling wound contraction. Finally, prospective simulations indicated that scaffolds with increased fiber dispersion (isotropy) exhibited reduced and more uniform wound contraction while supporting cell infiltration. By capturing the link between multi-scale scaffold biomechanics and cell-scaffold mechanochemical interactions, simulated healing outcomes aligned well with preclinical animal model data. STATEMENT OF SIGNIFICANCE: Skin wounds continue to be a significant burden to patients, physicians, and the healthcare system. Advancing the mechanistic understanding of the wound healing process, including multi-scale mechanobiological interactions amongst cells, the collagen scaffolding, and signaling molecules, will aide in the design of new skin restoration therapies. This work represents the first step towards integrating mechanobiology-based computational tools with in vitro and in vivo preclinical testing data for improving the design and evaluation of custom-fabricated collagen scaffolds for dermal replacement. Such an approach has potential to expedite development of new and more effective skin restoration therapies as well as improve patient-centered wound treatment.

Update on the practice of splinting during acute burn admission from the ACT study

INTRODUCTION

Burn scar contracture (BSC) is a common pathological outcome following burn injuries, leading to limitations in range of motion (ROM) of affected joints and impairment in function. Despite a paucity of research addressing its efficacy, static splinting of affected joints is a common preventative practice. A survey of therapists performed 25 years ago showed a widely divergent practice of splinting during the acute burn injury. We undertook this study to determine the current practice of splinting during the index admission for burn injuries.

METHODS

This is a review of a subset of patients enrolled in the Burn Patient Acuity Demographics, Scar Contractures and Rehabilitation Treatment Related to Patient Outcome Study (ACT) database. ACT was an observational multicenter study conducted from 2010-2013. The most commonly splinted joints (elbow, wrist, knee and ankle) and their 7 motions were included. Variables included patients' demographics, burn variables, rehabilitation treatment and hospital course details. Univariate and multivariate analysis of factors related to splinting was performed. P< 0.05 was significant.

RESULTS

Thirty percent of the study population (75 patients) underwent splinting during their hospitalization. Splinting was associated with larger burns and increased injury severity on the patient level and increased involvement with burns requiring grafting in the associated cutaneous functional unit (CFU) on the joint level. The requirement for skin grafting in both analyses remained independently related to splinting, with requirement for grafting in the associated CFU increasing the odds of splinting 6 times (OR =6.0, 95% CI=3.8-9.3, p<0.001). On average splinting was initiated about a third into the hospital length of stay (LOS, 35 ± 21% of LOS) and splints were worn for 50% (50 ± 26%) of the LOS. Joints were splinted for an average 15.1 ± 4.8 hours a day. The wrist was most frequently splinted joint being splinted with one third of wrists splinted ( 30.7%) while the knee was the least frequently splinted joint with 8.2% splinted. However, when splinted, the knee was splinted the most hours per day (17.6 ± 4.8 hours) and the ankle the least (14.4 ± 4.6 hours). Almost one third had splinting continued to discharge (20, 27%).

CONCLUSIONS

The current practice of splinting, especially the initiation, hours of wear and duration of splinting following acute burn injury remains variable. Splinting is independently related to grafting, grafting in the joint CFU, larger CFU involvement and is more likely to occur around the time of surgery. A future study looking at splinting application and its outcomes is warranted.

A systematic review and meta-analysis of urethral complications and outcomes in transgender men

BACKGROUND

Urologic problems, such as urethral fistulas and strictures, are among the most frequent complications occurring after phalloplasty. Although many studies have reported successful phalloplasty and urethral reconstruction with reliable outcomes in transgender men, no method has become standardized so far. This study aimed to summarize the results of reports on urological complications and outcomes in transgender men with respect to various types of urethral reconstruction.

METHODS

A comprehensive literature search of PubMed, Scopus, and Google Scholar databases was conducted for studies related to phalloplasty in transsexuals. Data on various phallic urethral techniques, urethral complications, and outcomes were collected and analyzed using the random-effects model.

RESULTS

A total of 21 studies (1,566 patients) were included: eight studies (1,061 patients) on "tube-in-tube," nine studies (273 patients) on "prelaminated flap," and six studies (221 patients) on "second flap." Compared with the tube-in-tube technique, the prelaminated flap was associated with a significantly higher urethral stricture/stenosis rate; however, there was no difference between the prelaminated flap and the second flap techniques. For all phalloplasty patients, the pool rate of urethral fistula or stenosis is 48.9%, the rate of the ability to void while standing is 91.5%, occurrence rate of tactile or erogenous sensation is 88%, the prosthesis complication rate is 27.9%, and patient-reported satisfactory outcome rate is 90.5%.

CONCLUSION

Urethral reconstruction with a prelaminated flap was associated with a significantly higher urethral stricture rate and increased need of revision surgery compared with that observed using a skin flap. Overall, most patients were able to void while standing and were satisfied with the outcomes.

Evaluation of the Extent of Primary Buccal Mucosal Graft Contracture in Augmentation Urethroplasty for Stricture Urethra: A Prospective Observational Study at a Tertiary Healthcare Centre

Introduction

Buccal mucosal graft (BMG) urethroplasty is considered as gold standard in the treatment of urethral stricture disease. The successful outcome after BMG urethroplasty varies between 66 and 99%. One of the possible causes for failure is BMG contracture. Primary BMG contracture rate is poorly understood and unreported. The present study aimed to evaluate the extent of contracture of buccal mucosa immediately after harvesting.

Materials and Methods

This was a prospective observational study conducted in the Department of Urology at our institute between January 2016 and December 2019. All patients with urethral stricture disease undergoing BMG urethroplasty for the first time were enrolled in the study after obtaining informed consent. Demographic and patient clinical profile was noted. Based on the intraoperative urethral stricture size, the preharvest graft was marked on the buccal mucosa and the size was calculated. Postharvest unstretched size of the graft was measured immediately after graft removal from the oral cavity. Alteration in BMG size was analysed using paired t-test.

Results

Forty-four patients were included in the study. Mean age of the patient was 53.6 years. Mean stricture length was 7.45 cm (range 4–12 cm). Mean pre- and postharvest BMG size was 8.3 × 1.5 cm and 7.6 × 1.3 cm, respectively. There was a 8.4% decrease in length and 9.5% decrease in width of the buccal mucosal graft.

Conclusion

Primary buccal mucosal graft contracture is around 8.4% in length and 9.5% in width. It would be better to mark wider than necessary while harvesting buccal mucosa so that tension-free anastomosis is performed.

Reconstruction of burn scar contracture deformity of the extremities using thin thoracodorsal artery perforator free flaps

BACKGROUND

Severe burn scar contracture of the extremities, especially the joint areas, causes aesthetic problems and functional limitation. Release of burn scar contractures requires complete removal of the scars and resurfacing of the resulting defects. Here, we describe thoracodorsal artery perforator (TDAP) free flaps for reconstructing burn scar contractures.

METHODS

Between August 2013 and July 2018, 25 patients with severe burn scar contractures of the extremities underwent reconstruction using TDAP free flaps. Twelve were men and the mean age of the patients was 38.1 years (range, 12-66 years). Five patients had upper extremity contractures and 20 had lower extremity contractures.

RESULTS

Twenty-one patients underwent reconstruction with a TDAP flap alone, while three received two perforator flaps, a TDAP and an anterolateral thigh flap or deep inferior epigastric artery perforator (DIEP) flap. The remaining patient received three perforator flaps, two TDAP and an anterolateral thigh flap. Fourteen patients had an improved range of motion after reconstruction. All the flaps survived except in the case of four patients who suffered partial loss of a TDAP flap. In one patient, there was partial skin graft loss at the donor site. The mean follow-up was 17.2 months (range 6-36 months).

CONCLUSION

Ideal reconstruction of burn scar contracture yielding functional and aesthetic results involves complete removal of scar tissue and reconstruction. Depending on the extent of the defect, the TDAP flap, with its thin and pliable tissue and minimal donor site morbidity, may be the best option for reconstruction of burn scar contracture.

Concepts in Early Reconstruction of the Burned Hand

BACKGROUND

Early reconstruction of burn sequelae of the hand can be challenging owing to high goals for functional and aesthetic outcome. A variety of reconstructive procedures with ascending levels of complexity exists and warrants careful indication.

METHODS

In this case series, the main reconstructive techniques for reconstruction of burn defects of the hand are described, illustrated, and discussed: split thickness skin grafting (STSG) with fibrin glue, dermal matrices with STSG, distant random pattern (abdominal bridge) flap, distant pedicled flap (superficial circumflex iliac artery flap), and free microvascular tissue transfer (anterolateral thigh flap). An algorithm for decision making in the reconstructive process is proposed.

RESULTS

Split thickness skin grafting provides sufficient coverage for partial thickness defects without exposure of functional structures; fixation with fibrin glue avoids unnecessary stapling. Dermal matrices under STSG provide vascularized granulation tissue on full thickness defects and can be used as salvage procedure on functional structures. Distant random pattern or pedicled flaps provide sufficient coverage of large full thickness defects with exposed functional structures but pose some challenges regarding patient compliance and immobilization. Free tissue transfer allows tailored reconstruction of large full thickness defects with exposed functional structures and can be safely and feasibly performed. Secondary and tertiary procedures are needed with more complex techniques; if applied correctly and consequently, all methods can yield favorable functional and aesthetic outcomes.

CONCLUSIONS

Reconstruction of the burned hand may require a broad armamentarium of surgical techniques with different levels of complexity, versatility, and applicability. Excellent results can be achieved with the right procedure for the right patient.

To Tie or Not to Tie-Over Full-Thickness Skin Grafts in Dermatologic Surgery: A Systematic Review of the Literature

BACKGROUND

Tie-over dressings are frequently used for skin grafts. Although a dressing is necessary for split-thickness skin grafts, their use in full-thickness skin grafts (FTSGs) is questionable.

OBJECTIVE

This review was conducted to investigate the influence of different tie overs and dressings on graft take for FTSGs in cutaneous surgery.

MATERIALS AND METHODS

An electronic database search was performed in MEDLINE, EMBASE, Web of Science, and the Cochrane library. The following search terms and comparable were used: skin transplantation, tie-over, fixation, sutures, and take.

RESULTS

Fifteen articles met the inclusion criteria. Eight studies describe no use of a tie-over dressing for FTSGs. Dressing types included antibacterial dressings, foam or sponges, and bolsters. The lowest graft take was 80% (with a tie-over dressing). The highest graft take was 100% (with and without a tie-over dressing).

CONCLUSION

The results show that, regardless of the technique used, the overall graft success rate is high. Although a definite recommendation could not be made, it seems that a graft without a tie-over dressing can suffice in certain circumstances.

The Impact of Fibrin Sealant Volume on Skin Graft Contraction in a Full-Thickness Skin Graft Model

BACKGROUND

Fibrin sealant has been used for skin grafting in anatomically difficult facial areas. Although biodegradable, an excess of fibrin sealant may inhibit skin graft healing by inhibiting diffusion at the graft-recipient bed interface. The impact of fibrin sealant volume on graft healing was examined in a rat full-thickness skin graft model.

METHODS

Seventy-two full-thickness 2.5 × 2.5-cm skin grafts were used on the dorsum of male Sprague-Dawley rats. The grafts were treated with three different volumes of fibrin sealant placed onto the recipient bed: 0.0 mL or normal saline (group 1), 0.1 mL (group 2), and 0.4 mL (group 3). Graft healing and complications were assessed using digital photographs and necropsies on postoperative days 3, 7, and 21.

RESULTS

Group 3 showed the greatest graft contraction on days 3 and 21, while group 2 showed the least contraction on all 3 postoperative days (P = 0.002, 0.004, and <0.001, respectively). Histopathologic analysis showed inflammatory foreign body reactions in group 3 on days 3 and 7, and less vascular density on day 21 (P = 0.003). Group 1 showed the highest incidence of hematoma (P = 0.004).

CONCLUSION

An excess volume of fibrin sealant may produce pathologic wound contraction in skin grafting because a skin graft lacks a vascular pedicle and is highly dependent on diffusion from the host environment. Before using fibrin sealant for skin grafting in facial areas where the aesthetic outcome is important, the appropriate volume to use can be determined.

Successful Full-Thickness Skin Regeneration Using Epidermal Stem Cells in Traumatic and Complex Wounds: Initial Experience

Skin grafts generated from cultured autologous epidermal stem cells may have potential advantages when compared to traditional skin grafting. In this report, we will share our initial experience with a new technique for the treatment of difficult cutaneous wounds. Eight patients with traumatic or complex wounds underwent full-thickness skin harvesting and processing of epidermal stem cells, followed by the application of our novel management protocol. The patients were at high risk for non-healing and/or severe scar formation due to large traumatic de-gloving crush injuries, wounds from necrotizing fasciitis, or chronic wounds from osteomyelitis. We examined the percent graft success, recipient to donor size ratios, the median time to epithelialization, and two-point sensory discrimination. An international scale (The Patient and Observer Scar Assessment Scale - POSAS) was used to evaluate wound cosmesis and included parameters such as pain, pruritus, vascularity, pigmentation, and thickness of the healing wound. In total, 10 out of 11 wounds had 100% survival of the graft, and one patient had an 80% graft take. The largest wound was 1600 cm^2, and all wounds were harvested from small-donor sites, which were closed primarily. The mean wound to donor ratio was >25:1. Most wounds were fully epithelialized within 30 days. Neurologically, four out of six patients studied exhibited two-point discrimination similar to the adjacent native uninjured skin. The majority of patients reported their wounds to have limited pain or pruritus, and similar pigmentation to adjacent skin. 

Buccal Mucosa Tube Graft for Failed Hypospadias Repair: Worth it or Not?

OBJECTIVE

To report the outcome of buccal mucosa tube graft (BMTG) over time in correcting failed hypospadias.

METHODS

We conducted a retrospective analysis, reviewing charts of all 69 patients who underwent BMTG to repair hypospadias between January 2005 and October 2016. Twenty-one patients were excluded, leaving 48 eligible study subjects. In patients with penile curvatures, corrective procedures (including urethral division, corporoplasty, and local skin flap) took place prior to grafting.

RESULTS

Mean age at surgery was 8.96 years, and mean duration of follow-up was 73.10 ± 30.31 months. A mean of 1.88 previous surgeries was recorded. During follow-up, only 7 patients (14.5%) were complication free. The other 41 patients required at least 1 additional procedure. Stricture-free rates were 50%, 35.4%, and 27% at 1, 3, and 12 months after BMTG, respectively. Among 37 patients with postoperative stricture, 25 were treated only by endoscopic procedures. Single operation prior to BMTG (P= .004) and usage of larger catheter size (>8Fr) (P = .029) were confirmed significant factors associated with better stricture-free survival after BMTG by log-rank test. After several additional procedures, 46 patients (95.8%) reported normal urination with mean maximal urinary flow of 9.55 mL/s and post-void residual of 16.08 mL for at least 12 months on last visit.

CONCLUSION

BMTG after failed hypospadias repair seems prone to complications, primarily urethral stricture. However, a large number of patients with postoperative stricture could be treated simply by endoscopic procedures. Given the better results of staged approach, BMTG should be only applied to highly selected patients with failed hypospadias.

The effects of cross-linking a collagen-elastin dermal template on scaffold bio-stability and degradation

MatriDerm is a collagen-elastin dermal template that promotes regeneration in full-thickness wound repair. Due to its noncross-linked status, MatriDerm biodegrades quickly in a wound. Facilitating vascularization and dermal repair, it is desirable for MatriDerm to remain present until the wound healing process is complete, optimizing tissue regeneration and reducing wound contraction. The aim of this study was to investigate the effect of cross-linking MatriDerm on its mechanical and biological properties and to enhance its regenerative functionality. MatriDerm was chemically cross-linked and characterized in comparison with noncross-linked MatriDerm. Scaffold properties including surface morphology, protein release and mechanical strength were assessed. Cell-scaffold interaction, cell proliferation and migration were examined using human dermal fibroblasts. Scaffold biodegradation and its impact on wound healing and contraction were studied in a mouse model. Results showed that cross-linked MatriDerm displayed a small reduction in pore size, significantly less protein loss and a threefold increase in tensile strength. A significant increase in fibroblast proliferation and migration was observed in cross-linked MatriDerm with reduced scaffold contraction in vitro. In the mouse model, noncross-linked MatriDerm was almost completely biodegraded after 14 days whereas cross-linked MatriDerm remained intact. No significant difference in wound contraction was found between scaffolds. In conclusion, cross-linked MatriDerm showed a significant increase in stability and strength, enhancing its durability and cell-scaffold interaction. in vivo analysis showed cross-linked MatriDerm had a reduced biodegradation rate with a similar host response. The extended structural integrity of cross-linked MatriDerm could potentially facilitate improved skin tissue regeneration, promoting the formation of a more pliable scar.

Open-label Venous Leg Ulcer Pilot Study Using a Novel Autolologous Homologous Skin Construct

Venous leg ulcers (VLUs) are often refractory to compression therapy, and their prevalence is increasing. An autologous homologous skin construct (AHSC) that uses the endogenous regenerative capacity of healthy skin has been developed to treat cutaneous defects, with a single application. The ability of AHSC to close VLUs with a single treatment was evaluated in an open-label, single-arm feasibility study to test the hypothesis that AHSC treatment will result in wound closure by providing healthy autologous tissue to the wound bed.

METHODS

Ten VLUs were treated with a single application of AHSC. A 1.5 cm2 full-thickness skin harvest from the proximal calf was collected and sent to a Food and Drug Administration-registered facility, where it was processed into AHSC and returned to the provider within 48 hours. AHSC was spread evenly across the wound and dressed with silicone. The primary endpoint was wound closure rate at 12 weeks. Wound closure was followed with 3-dimensional planimetry, and closure was confirmed by a panel of plastic surgeons. Additional endpoints followed for 12 weeks included graft take, harvest site closure, adverse event rate, complications, and patient-reported pain.

RESULTS

All 10 VLUs demonstrated successful graft take as evidenced by graft persisting in wound and harvest site closure. Eight VLUs exhibited complete closure within 12 weeks. One VLU that failed to heal with a prior split thickness skin graft closed within 13.5 weeks with AHSC. The mean time of closure was 34 days (95% confidence interval, 14-53). Pain improved by closure confirmation visit. There was 1 serious adverse event unrelated to the product or procedure.

CONCLUSION

This pilot study demonstrated that AHSC may be a viable single-application topical intervention for VLUs and warrants further investigation in larger, controlled studies.

Awareness and attitude of general population regarding allograft skin donation in Riyadh, Saudi Arabia: Cross-sectional study

INTRODUCTION

Burns are one of the major health issues that considerably affect variable groups of the population, varying in age and severity. Despite advances in burn surgical and non-surgical treatments, patient's appearance still represents public health issue. In regards to surgical treatment of burns, skin grafting is still considered the gold standard. One of the major burdens in the burn surgical treatments is the availability of the skin for grafting. As for the non-surgical treatment different modalities of skin dressings or substitutes are still available as an option.

METHODS

A validated questionnaire based study was utilized to acquire assessment of the overall general population knowledge, awareness and attitude toward skin donation. In addition, it surveyed community personal willingness to donate their skin to a skin bank after being deceased, to help solve skin shortages due to the lack of skin banks in Saudi Arabia.

RESULTS

A total of 698 individuals completed the questionnaire over the period of 5 months, from February 2018 till June 2018. Married, postgraduate females, with a history of burn in close family members or similar individuals showed a positive attitude toward skin donation. However, 22% of the participants did not agree to donate their skin due to religious reasons.

CONCLUSION

The study concluded that the majority of participants were willing to donate their skin, and they were aware of the concept of skin donation and its crucial importance in surgical burn management. The current study showed the majority of participants were aware of skin donation and skin use for burn treatment, in addition to having positive attitude toward skin donation. Men were more aware than the women of skin donation. Religious concern was a major reason for participants' skin donation refusal, an issue that can be addressed by contacting Islamic scholars to issue a Fatwa approving the cause.

Design and biofabrication of dermal regeneration scaffolds: role of oligomeric collagen fibril density and architecture

Aim: To evaluate dermal regeneration scaffolds custom-fabricated from fibril-forming oligomeric collagen where the total content and spatial gradient of collagen fibrils was specified. Materials & methods: Microstructural and mechanical features were verified by electron microscopy and tensile testing. The ability of dermal scaffolds to induce regeneration of rat full-thickness skin wounds was determined and compared with no fill control, autograft skin and a commercial collagen dressing. Results: Increasing fibril content of oligomer scaffolds inhibited wound contraction and decreased myofibroblast marker expression. Cellular and vascular infiltration of scaffolds over the 14-day period varied with the graded density and orientation of fibrils. Conclusion: Fibril content, spatial gradient and orientation are important collagen scaffold design considerations for promoting vascularization and dermal regeneration while reducing wound contraction.

Vestibuloplasty covering titanium mesh with grafted free gingiva on anterior mandible: technical report and rationale

This paper describes a patient with an insufficient vestibular depth for a removable partial denture who underwent vestibuloplasty with a free gingival graft using a titanium mesh in the anterior mandible. Free gingiva was harvested from the palatal mucosa, and a partial thickness flap was elevated at the recipient site. After minimal suturing for the graft, a titanium mesh was fixed over the graft. The mesh was removed four weeks after surgery. The patient obtained an adequate vestibular depth and keratinized gingiva eight weeks after surgery without any complications. In this case, an appropriate vestibular depth and keratinized gingiva were easily obtained by vestibuloplasty using a titanium mesh.

Longitudinal extensibility of the dorsal skin of the hand

We aimed to assess the longitudinal extensibility of the dorsal skin of the hand. Measurements were done in five hand positions on the dominant hands of 64 volunteers. The positions were full flexion of the wrist and fingers, drop hand, flat hand, hand with opposed thumb and full extension. Dorsal marks were made on the skin in full flexion. The marks were transferred to transparent parchment paper strips with the hand in the different positions. Skin extensibility was assessed by the change in the distance between two skin marks from the full extension position to the other positions. Opposition required the highest degree of skin extensibility in the dorsal radial region, followed orderly by ulnar and central regions. Generally, the extensibility increased from distal to proximal and from ulnar to radial. These findings may be useful in the management of dorsal hand soft tissue defects.

Regeneration and expansion of autologous full-thickness skin through a self-propagating autologous skin graft technology

New autologous skin regeneration technology yielded full-thickness skin as evidenced by clinical observation and skin biopsy 5 months after surgery, providing relief for debilitating split-thickness skin graft contracture in a pediatric burn case.

Clinical experience with surgical debridement and simultaneous meshed skin grafts in treating biofilm-associated infection: an exploratory retrospective pilot study

Current treatment guidelines for biofilm-associated infections (BAI) recommend repeated sharp/surgical debridement followed by treatment with antimicrobial agents until the wound becomes self-sustaining in terms of a positive wound-healing trajectory. However, complete removal of a biofilm is unlikely, and biofilms reform rapidly. We have treated BAI in patients with chronic diabetic ulcers using a meshed skin graft combined with negative pressure wound therapy (NPWT) immediately after surgical debridement, rather than waiting until the development of clean and healthy granulation tissue; the purpose of this exploratory study was to report the clinical results of this treatment strategy. This retrospective study included 75 patients with chronic diabetic ulcers who were treated for BAI by using surgical debridement, simultaneous meshed skin grafts, and NPWT. Healing time along with the percentage of complete wound closure within 12 weeks were evaluated; bacteria isolated from the wounds and their relation to the wound healing rate were investigated. All 75 wounds healed successfully, and the mean time for complete wound healing was 3.5 ± 1.8 weeks. In particular, 76% of wounds healed uneventfully without graft loss. A mean of 3.3 bacterial colonies/wound were isolated; however, no significant difference in wound healing was observed between the monomicrobial and polymicrobial groups. This exploratory study suggests that surgical debridement and simultaneous meshed skin grafts combined with NPWT may be successfully used to combat BAI in patients with chronic diabetic ulcers. We look forward to larger pivotal studies to confirm or refute these initially promising findings.

Safety and efficacy of dermal fibroblast conditioned medium (DFCM) fortified collagen hydrogel as acellular 3D skin patch

Skin substitutes are one of the main treatments for skin loss, and a skin substitute that is readily available would be the best treatment option. However, most cell-based skin substitutes require long production times, and therefore, patients endure long waiting times. The proteins secreted from the cells and tissues play vital roles in promoting wound healing. Thus, we aimed to develop an acellular three-dimensional (3D) skin patch with dermal fibroblast conditioned medium (DFCM) and collagen hydrogel for immediate treatment of skin loss. Fibroblasts from human skin samples were cultured using serum-free keratinocyte-specific media (KM1 or KM2) and serum-free fibroblast-specific medium (FM) to obtain DFCM-KM1, DFCM-KM2, and DFCM-FM, respectively. The acellular 3D skin patch was soft, semi-solid, and translucent. Collagen mixed with DFCM-KM1 and DFCM-KM2 showed higher protein release compared to collagen plus DFCM-FM. In vitro and in vivo testing revealed that DFCM and collagen hydrogel did not induce an immune response. The implantation of the 3D skin patch with or without DFCM on the dorsum of BALB/c mice demonstrated a significantly faster healing rate compared to the no-treatment group 7 days after implantation, and all groups had complete re-epithelialization at day 17. Histological analysis confirmed the structure and integrity of the regenerated skin, with positive expression of cytokeratin 14 and type I collagen in the epidermal and dermal layer, respectively. These findings highlight the possibility of using fibroblast secretory factors together with collagen hydrogel in an acellular 3D skin patch that can be used allogeneically for immediate treatment of full-thickness skin loss.

Skin bioprinting: the future of burn wound reconstruction?

Burns are a significant cause of trauma, and over the years, the focus of patient care has shifted from just survival to facilitation of improved functional outcomes. Typically, burn treatment, especially in the case of extensive burn injuries, involves surgical excision of injured skin and reconstruction of the burn injury with the aid of skin substitutes. Conventional skin substitutes do not contain all skin cell types and do not facilitate recapitulation of native skin physiology. Three-dimensional (3D) bioprinting for reconstruction of burn injuries involves layer-by-layer deposition of cells along with scaffolding materials over the injured areas. Skin bioprinting can be done either in situ or in vitro. Both these approaches are similar except for the site of printing and tissue maturation. There are technological and regulatory challenges that need to be overcome for clinical translation of bioprinted skin for burn reconstruction. However, the use of bioprinting for skin reconstruction following burns is promising; bioprinting will enable accurate placement of cell types and precise and reproducible fabrication of constructs to replace the injured or damaged sites. Overall, 3D bioprinting is a very transformative technology, and its use for wound reconstruction will lead to a paradigm shift in patient outcomes. In this review, we aim to introduce bioprinting, the different stages involved, in vitro and in vivo skin bioprinting, and the various clinical and regulatory challenges in adoption of this technology.

Application of hydrosurgery for burn wound debridement: An 8-year cohort analysis

INTRODUCTION

During the last decade, the Versajet™ hydrosurgery system has become popular as a tool for tangential excision in burn surgery. Although hydrosurgery is thought to be a more precise and controlled manner for burn debridement prior to skin grafting, burn specialists decide individually whether hydrosurgery should be applied in a specific patient or not. The aim of this study was to gain insight in which patients hydrosurgery is used in specialized burn care in the Netherlands.

METHODS

A retrospective study was conducted in all patients admitted to a Dutch burn centre between 2009 and 2016. All patients with burns that underwent surgical debridement were included. Data were collected using the national Dutch Burn Repository R3.

RESULTS

Data of 2113 eligible patients were assessed. These patients were treated with hydrosurgical debridement (23.9%), conventional debridement (47.7%) or a combination of these techniques (28.3%). Independent predictors for the use of hydrosurgery were a younger age, scalds, a larger percentage of total body surface area (TBSA) burned, head and neck burns and arm burns. Differences in surgical management and clinical outcome were found between the three groups.

CONCLUSION

The use of hydrosurgery for burn wound debridement prior to skin grafting is substantial. Independent predictors for the use of hydrosurgery were mainly burn related and consisted of a younger age, scalds, a larger TBSA burned, and burns on irregularly contoured body areas. Randomized studies addressing scar quality are needed to open new perspectives on the potential benefits of hydrosurgical burn wound debridement.

Construction of low contracted 3D skin equivalents by genipin cross-linking

Continuous contraction of 3D skin equivalents in construction and use restricts their applications in clinical and pharmaceutical practices. So far, no effective method has been developed to inhibit such contraction. Hence, low cytotoxic cross-linkers, 1-ethyl-3-3-dimethylaminopropylcarbodiimide hydrochloride (EDC) and genipin, are investigated to reduce the contraction in this study. As found, both genipin and EDC at 0.2 and 0.4 mmol/L are nontoxic to collagen-entrapped fibroblasts and upregulate the extracellular matrix expression of fibroblasts in cross-linked collagen. Particularly, collagen cross-linking by intermediate concentrations of genipin, specifically 0.4 mmol/L, greatly reduces the contraction of 3D skin equivalents from 87% to 28% (n = 9, P < 0.05), while the collagen after EDC cross-linking at 0.4 mmol/L still presented severe contraction of 64% over a 21-day follow-up period. The inhibited contraction might relate to the increased gel stiffness and slowed collagen degradation. Moreover, the genipin cross-linking does not impair the formation of epidermal layers and improves the epidermal-dermal junction of skin equivalents as well. In this regard, genipin cross-linking might facilitate the applications of 3D skin equivalents in clinical practices and pharmacology testing.

Tie-Over Bolster Dressings vs Basting Sutures for the Closure of Full-Thickness Skin Grafts: A Review of the Literature

BACKGROUND

Full-thickness skin grafting is a well-established technique in the reconstruction of various tissue defects and wounds. However, lack of uniformity in the procedure of closing and securing the grafts has led to a wide range of different techniques.

OBJECTIVE

This article reviews the use of tie-over bolster dressings compared to basting sutures for the fixation and postsurgical immobilization of full-thickness skin grafts (FTSGs), discusses details of each method, and proposes a practice guideline for the closure of FTSGs.

METHODS

A traditional review of the literature was performed through a search of PubMed using the following keywords: full-thickness skin graft, FTSG, closure, suture, tie-over bolster, quilting, and bolster.

RESULTS

The current literature regarding tie-over bolster dressings does not demonstrate improved outcomes compared to quilting sutures. The 2 techniques appear equivalent in terms of utility and outcome, both possessing distinct advantages and disadvantages.

CONCLUSION

Despite minimal head-to-head studies between tie-over bolsters and quilting, the best evidence from the literature appears to show comparable results regarding graft take, cosmetic outcomes, and postoperative complications. Ultimately, the choice of using a tie-over bolster technique or quilting sutures relies on surgeon preference and anatomic location.

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.

Overcoming scarring in the urethra: Challenges for tissue engineering

Urethral stricture disease is increasingly common occurring in about 1% of males over the age of 55. The stricture tissue is rich in myofibroblasts and multi-nucleated giant cells which are thought to be related to stricture formation and collagen synthesis. An increase in collagen is associated with the loss of the normal vasculature of the normal urethra. The actual incidence differs based on worldwide populations, geography, and income. The stricture aetiology, location, length and patient's age and comorbidity are important in deciding the course of treatment. In this review we aim to summarise the existing knowledge of the aetiology of urethral strictures, review current treatment regimens, and present the challenges of using tissue-engineered buccal mucosa (TEBM) to repair scarring of the urethra. In asking this question we are also mindful that recurrent fibrosis occurs in other tissues-how can we learn from these other pathologies?

Multilineage Constructs for Scaffold-Based Tissue Engineering: A Review of Tissue-Specific Challenges

There is a growing interest in the regeneration of tissue in interfacial regions, where biological, physical, and chemical attributes vary across tissue type. The simultaneous use of distinct cell lineages can help in developing in vitro structures, analogous to native composite tissues. This literature review gathers the recent reports that have investigated multiple cell types of various sources and lineages in a coculture system for tissue-engineered constructs. Such studies aim at mimicking the native organization of tissues and their interfaces, and/or to improve the development of complex tissue substitutes. This paper thus distinguishes itself from those focusing on technical aspects of coculturing for a single specific tissue. The first part of this review is dedicated to variables of cocultured tissue engineering such as scaffold, cells, and in vitro culture environment. Next, tissue-specific coculture methods and approaches are covered for the most studied tissues. Finally, cross-analysis is performed to highlight emerging trends in coculture principles and to discuss how tissue-specific challenges can inspire new approaches for regeneration of different interfaces to improve the outcomes of various tissue engineering strategies.