Epidermal skin grafting

Application of pulsed electric field technology to skin engineering

Tissue engineering encompasses a range of techniques that direct the growth of cells into a living tissue construct for regenerative medicine applications, disease models, drug discovery, and safety testing. These techniques have been implemented to alleviate the clinical burdens of impaired healing of skin, bone, and other tissues. Construct development requires the integration of tissue-specific cells and/or an extracellular matrix-mimicking biomaterial for structural support. Production of such constructs is generally expensive and environmentally costly, thus eco-sustainable approaches should be explored. Pulsed electric field (PEF) technology is a nonthermal physical processing method commonly used in food production and biomedical applications. In this review, the key principles of PEF and the application of PEF technology for skin engineering will be discussed, with an emphasis on how PEF can be applied to skin cells to modify their behaviour, and to biomaterials to assist in their isolation or sterilisation, or to modify their physical properties. The findings indicate that the success of PEF in tissue engineering will be reliant on systematic evaluation of key parameters, such as electric field strength, and their impact on different skin cell and biomaterial types. Linking tangible input parameters to biological responses critical to healing will assist with the development of PEF as a sustainable tool for skin repair and other tissue engineering applications.

Exploring an Innovative Approach: Integrating Negative-Pressure Wound Therapy with Silver Nanoparticle Dressings in Skin Graft Procedures

BACKGROUND

Skin grafting is a helpful instrument in a plastic surgeon's arsenal. Several types of dressings were designed to facilitate the process of graft integration. Negative-pressure wound therapy is a proven dressing method, enhancing graft survival through several mechanisms: aspiration of secretions, stimulation of neoangiogenesis, and promotion of an anti-inflammatory environment. Silver nanoparticle dressings also bring multiple benefits by bearing an antimicrobial effect and providing a humid medium, which are favorable for epithelialization. The combination of NPWT (negative-pressure wound therapy) with AgNPs (silver nanoparticles) has not been widely studied.

MATERIALS AND METHODS

This study aimed to compare the outcomes of silver nanoparticle sheets with the combination of negative-pressure wound therapy and silver nanoparticle dressings. We conducted a comparative prospective study on 80 patients admitted to the Plastic Surgery Department of "Prof. Dr. Agrippa Ionescu" Emergency Clinical Hospital between 1st of January 2020 and 31st of December 2022. The study population was randomized to receive either silver nanoparticle dressings or negative-pressure wound therapy (NPWT) combined with silver nanoparticle dressings. Various parameters were monitored, including patient comorbidities and graft-related data such as defect etiology, graft integration, and graft size. Dressings were changed, and graft status was evaluated at 7, 10, and 14 days postoperatively. Additionally, baseline C-reactive protein (CRP) levels were measured before surgery and 7, 10, and 14 days postoperatively.

RESULTS

The study demonstrated an enhanced integration of skin grafts at all evaluation stages when employing NPWT combined with AgNPs, particularly evident 10 days post operation. Significant variations in graft integration were also observed based on factors such as diabetes, cardiovascular disease, graft size, or the origin of the grafted defect. Moreover, dynamic C-reactive protein monitoring showed a statistically significant decrease in CRP levels 10 days post operation among patients treated with NPWT in conjunction with silver dressing, consistent with the nearly complete integration of skin grafts at this evaluation threshold.

CONCLUSION

Several factors influence the postoperative evolution of split-skin grafts. Postoperative dressings target local factors to enhance graft integration further. Our research demonstrated that the innovative combination of NPWT-assisted dressings, complemented by a silver nanoparticle sheet, resulted in improved benefits for graft integration and the alleviation of systemic inflammation.

Electrospinning/3D printing drug-loaded antibacterial polycaprolactone nanofiber/sodium alginate-gelatin hydrogel bilayer scaffold for skin wound repair

Skin injuries and defects, as a common clinical issue, still cannot be perfectly repaired at present, particularly large-scale and infected skin defects. Therefore, in this work, a drug-loaded bilayer skin scaffold was developed for repairing full-thickness skin defects. Briefly, amoxicillin (AMX) was loaded on polycaprolactone (PCL) nanofiber via electrospinning to form the antibacterial nanofiber membrane (PCL-AMX) as the outer layer of scaffold to mimic epidermis. To maintain wound wettability and promote wound healing, external human epidermal growth factor (rhEGF) was loaded in sodium alginate-gelatin to form the hydrogel structure (SG-rhEGF) via 3D printing as inner layer of scaffold to mimic dermis. AMX and rhEGF were successfully loaded into the scaffold. The scaffold exhibited excellent physicochemical properties, with elongation at break and tensile modulus were 102.09 ± 6.74 % and 206.83 ± 32.10 kPa, respectively; the outer layer was hydrophobic (WCA was 112.09 ± 4.67°), while the inner layer was hydrophilic (WCA was 48.87 ± 5.52°). Meanwhile, the scaffold showed excellent drug release and antibacterial characteristics. In vitro and in vivo studies indicated that the fabricated scaffold could enhance cell adhesion and proliferation, and promote skin wound healing, with favorable biocompatibility and great potential for skin regeneration and clinical application.

Monitoring angiogenesis in skin autografts using photoacoustic microscopy

BACKGROUND

Skin autografts have been broadly used to manage the skin and soft tissue defects. It is important for surgeons to assess the vitality of skin autografts via observing the angiogenesis. However, there is lack of reliable approach for giving the quantitative angiogenesis information on the skin autografts. Recently, photoacoustic microscopy imaging has attracted much attention based on its good performance in angiography.

METHODS

In this study, we aim to monitor angiogenesis in skin autografts via PAM, and further verify its clinical potential for the early prediction of skin autografts clinical outcome.

RESULTS AND CONCLUSIONS

The results indicate that PAM is a feasible, precise, high-resolution, noninvasive technique for the early prediction of necrosis of skin autografts via monitoring the angiogenesis, providing a promising tool for surgeons to use this surgical technology.

Healing techniques for split-thickness skin grafts donor sites. Umbrella review

OBJECTIVES

To summarize the existing evidence and provide recommendations for the most effective management of partial-thickness graft donor sites in adults, with the goals of enhancing re-epithelialization, reducing pain, and preventing infection.

METHODOLOGY

Umbrella review. A systematic search was conducted encompassing databases such as Pubmed, CUIDEN, Cochrane Library, CINHAL Plus, SCOPUS, and LILACS. The search targeted systematic reviews published since 2011 that focused on examining the effectiveness of different approaches for the treatment of partial-thickness graft donor sites. Reviews with a low critical appraisal score according to AMSTAR 2 were excluded. The included reviews were evaluated using the SIGN scale to assess the level of evidence and grade the recommendations.

RESULTS

Five systematic reviews with meta-analysis were incorporated in the analysis. Platelet-rich plasma and human amniotic membrane demonstrated statistically significant improvements in re-epithelialization and pain reduction when compared to the control group. Moreover, platelet-rich plasma also exhibited a decrease in wound infection rates. Recombinant human growth hormone was found to expedite the re-epithelialization process.

CONCLUSIONS

Based on the findings, the use of platelet-rich plasma is recommended to enhance re-epithelialization, alleviate pain, and reduce infection in partial-thickness graft donor sites among adults. Application of human amniotic membrane is recommended to accelerate re-epithelialization and alleviate pain, while recombinant human growth hormone is suggested to expedite the overall healing time of these wounds.

Multicellular bioprinted skin facilitates human-like skin architecture in vivo

Bioprinting is a promising alternative method to generate skin substitutes because it can replicate the structural organization of the skin into biomimetic layers in vitro. In this study, six primary human skin cell types were used to bioprint a trilayer skin construct consisting of epidermis, dermis, and hypodermis. Transplantation of the bioprinted skin with human cells onto full-thickness wounds of nu/nu mice promoted rapid vascularization and formation of epidermal rete ridges analogous to the native human epidermis, with a normal-looking extracellular matrix. Cell-specific staining confirmed the integration of the implanted cells into the regenerated skin. Using a similar approach, a 5 centimeter-by-5 centimeter bioprinted autologous porcine skin graft was transplanted onto full-thickness wounds in a porcine excisional wound model. The bioprinted skin graft improved epithelialization, reduced skin contraction, and supported normal collagen organization with reduced fibrosis. Differential gene expression demonstrated pro-remodeling protease activity in wounds transplanted with bioprinted autologous skin grafts. These results demonstrate that bioprinted skin can support skin regeneration to allow for nonfibrotic wound healing and suggest that the skin bioprinting technology may be applicable for human clinical use.

Vascular endothelial growth factor a modified mRNA engineered cellular electrospun membrane complexes promotes mouse skin wound repair

Artificial skin substitutes are one of the most promising areas of wound healing research; however, graft survival largely depends on how the treatment is performed. Early angiogenesis is essential for wound healing and graft survival and vascular endothelial growth factor A (VEGFA) is an important cytokine that stimulates angiogenesis. Here, we first investigated the effects of different ratios of collagen (BC) and gelatin blended with poly (l-lactide-co-caprolactone) (PLCL) on nanofibrous membranes. The Young's modulus and cell proliferation were significantly higher in the 50% BC group than that in all other groups. Then, cellular electrospun membrane complexes (CEMC) were successfully constructed from nanoscaffolds and fibroblasts extracted from human foreskin and engineered with controlled autocrine VEGFA by transfecting VEGFA modified mRNA (modRNA). Engineered CEMC significantly promoted wound healing in vivo and contributed to stable vascular network formation in the grafted area, thereby increasing the survival rate of the engineered skin. This study provides a potential solution for wound healing while establishing the value of different RNA modification methods for various engineered skins in the future, thereby advancing engineered skin development.

Biomaterials derived from hard palate mucosa for tissue engineering and regenerative medicine

Autologous materials have superior biosafety and are widely used in clinical practice. Due to its excellent trauma-healing ability, the hard palate mucosa (HPM) has become a hot spot for autologous donor area research. Multiple studies have conducted an in-depth analysis of the healing ability of the HPM at the cellular and molecular levels. In addition, the HPM has good maneuverability as a donor area for soft tissue grafts, and researchers have isolated various specific mesenchymal stem cells (MSCs) from HPM. Free soft tissue grafts obtained from the HPM have been widely used in the clinic and have played an essential role in dentistry, eyelid reconstruction, and the repair of other specific soft tissue defects. This article reviews the advantages of HPM as a donor area and its related mechanisms, classes of HPM-derived biomaterials, the current status of clinical applications, challenges, and future development directions.

Enhancing Lower Extremity Defect Coverage: High Viability Ultra-Thin Split-Thickness Skin Grafts Obtained from the Scalp

BACKGROUND

Repairing lower extremity defects presents challenges due to the scarcity of available local tissue. Skin grafting is a widely employed technique for addressing non-healing ulcers, improving the quality of life of patients and minimizing discomfort. However, using traditional donor sites, such as the thigh, can hinder mobility and result in noticeable scarring and pigmentation changes.

OBJECTIVES

This study aims to assess the effectiveness of a novel approach utilizing autologous ultra-thin split-thickness skin grafts (STSGs) harvested from the scalp using a disposable, commercially available razor blade named DermaBlade.

METHODS

Fifteen patients (median age: 72 years, eight males and seven females) with diverse lower limb lesions, including carcinomas and ulcers of varying etiologies, were prospectively enrolled. Donor sites included the sideburn extending to the hairy temporal skin (nine cases) and hairy occipital skin (six cases). Ultra-thin skin strips (<0.2 mm thick) were obtained from the scalp through the use of the disposable flexible blade DermaBlade. The strips were positioned over the receptor area with no sutures in most cases and secured using dressings. A substantial majority of patients (90%) achieved successful graft take with no complications. Swift re-epithelialization occurred within a median of 12 days for the donor site and 24 days for the receptor site. No hair transfer or alopecic scars were noted.

CONCLUSIONS

In contrast to traditional grafting methods, DermaBlade-assisted scalp grafting yields highly viable STSGs that adhere to wound beds without the need for sutures. Notable advantages of this technique encompass rapid wound healing, minimal complications, and superior cosmetic outcomes. Furthermore, it avoids scarring and alopecia, making it a promising approach for addressing lower extremity defects.

Full-thickness skin columns: A method to reduce healing time and donor site morbidity in deep partial-thickness burns

The current standard of care for the coverage of large wounds often involves split thickness skin grafts (STSGs) which have numerous limitations. One promising technique that has gained traction is fractional autologous skin grafting using full-thickness skin columns (FTSC). Harvesting occurs orthogonally by taking numerous individual skin columns containing the epidermis down through the dermis and transferring them to the wound bed. The purpose of this porcine study was to investigate the efficacy of implanting FTSCs directly into deep partial-thickness burn wounds, as well as examining donor site healing at the maximal harvest density. It was hypothesised that by utilising FTSCs, the rate of healing in deep partial thickness burns can be improved without incurring the donor morbidity seen in other methods of skin grafting. Deep partial-thickness burns were created on the dorsum of female red duroc swine, debrided 3 days later and FTSCs were implanted at varying expansion ratios directly into the burn wounds. At day 14, 1:50 expansion ratio showed significantly faster re-epithelialisation compared to the debrided burn control and 1:200. Donor sites (at 7%-10% harvest density) were 100% re-epithelialised by day 7. Additionally, the maximal harvest density was determined to be 28% in an ex vivo model, which then five donor sites were harvested at 28% density on a red duroc swine and compared to five STSG donor sites. At maximal harvest density, FTSC donor sites were significantly less hypopigmented compared to STSGs, but no significant differences were observed in re-epithelialisation, contraction, blood flow or dermal thickness. In conclusion, implantation directly into deep partial-thickness burns is a viable option for the application of FTSCs, favouring lower expansion ratios like 1:50 or lower. Little difference in donor site morbidity was observed between FTSC at a maximal harvest density of 28% and STSGs, exceeding the optimal harvest density.

Burn Scar Management and Reconstructive Surgery

This chapter highlights the importance of a comprehensive burn scar treatment plan in approaching a burn survivor. General concepts of burn scar physiology and a practical system to describe burn scars based on cause, biology, and symptoms are presented. Common scar management modalities including nonsurgical, surgical, and adjuvant therapies are further discussed.

Full-Thickness Skin Graft from the Submental Triangle for Facial Defect Reconstruction

Full-thickness skin grafting plays an important role in facial reconstruction for excessive skin defects or possible eye, nose, or lip distortion after a malignant tumor excision. For esthetic consideration, full-thickness skin grafts of the retroauricular region can be used, but the amount of skin is limited. The skin of the submental triangle has similar cutaneous features and provides a large graft. We aimed to evaluate the feasibility of using full-thickness skin grafts harvested from the submental triangle to reconstruct facial skin defects. We retrospectively analyzed 14 cases treated at a single institution to evaluate the clinical and esthetic outcomes, and patients' satisfaction. During 6-24 months of follow-up, the wounds healed with well-matched color, texture, and contour. No obvious hypertrophies or distortions were observed. Additionally, the removal of redundant submental triangle skin resulted in the secondary gain of double chin reduction. All patients were satisfied with the appearance of both donor and recipient sites. In conclusion, the submental triangle is a good possible option for full-thickness skin grafts used to resurface facial skin defects. Using this approach, both donor and recipient sites can achieve satisfactory esthetic outcomes.

Delayed primary intention with full-thickness skin graft in distal interphalangeal injury: A rare case report

INTRODUCTION AND IMPORTANCE

The fingertip injury is the most common in the hand area. In this regard, skin grafting can be considered to preserve sensation, due to its functional importance, particularly for distal tip injuries. A full-thickness skin graft (FTSG) results in excellent function after engraftment and should be considered in reconstructing functionally and aesthetically important areas. Moreover, a thorough understanding of FTSG is required for a surgeon to have an excellent outcome.

CASE PRESENTATION

A 38-year-old man had the third fingertip injury of his right hand after being crushed by a mill. Physical examination revealed exposed bone distal to DIP, with intact periosteum and nail plate, negative active bleeding, and negative contaminants. There was no tendon or soft tissue left above the periosteum. In addition, an X-ray of the right manus revealed no fracture. The wound was applied with hydrogel and petroleum gauze to maintain hydration. A wound toilet was performed, followed by the closure of the wound with full-thickness skin grafting (FTSG). Follow-up was done in the first week and the fourth week after the procedure, as they showed good aesthetic results with satisfactory function. The sensory recovery showed normal result for touch and vibration. Meanwhile, sharp pain and warmth object sensation were minimally diminished.

CLINICAL DISCUSSION

A literature review concludes that FTSGs are generally unreliable in cases with over poorly vascularized beds, and FTSG will only work with no serious blood supply issues. Therefore, severe fingertip injury was reconstructed by the graft.

CONCLUSION

This procedure showed excellent graft survival with no additional surgical injury of the normal finger, satisfactory functional and aesthetic outcomes, and no need for secondary debulking procedures. Potential disadvantages consisted of insufficient volume of soft tissue and graft hyperpigmentation. However, delayed primary wound closure by FTSG may be an option for treating full-thickness finger defects with bone or tendon exposure.

Applications of MXene and its modified materials in skin wound repair

The rapid healing and repair of skin wounds has been receiving much clinical attention. Covering the wound with wound dressing to promote wound healing is currently the main treatment for skin wound repair. However, the performance of wound dressing prepared by a single material is limited and cannot meet the requirements of complex conditions for wound healing. MXene is a new two-dimensional material with electrical conductivity, antibacterial and photothermal properties and other physical and biological properties, which has a wide range of applications in the field of biomedicine. Based on the pathophysiological process of wound healing and the properties of ideal wound dressing, this review will introduce the preparation and modification methods of MXene, systematically summarize and review the application status and mechanism of MXene in skin wound healing, and provide guidance for subsequent researchers to further apply MXene in the design of skin wound dressing.

Nagging Pain and Foot Ulcers Can be Treated into Remission

Lower extremity ulcerations are very common in patients with diabetes. These wounds lead to amputation in a surprisingly large percentage of patients with diabetes. The mortality rate following amputation in a patient with diabetes is alarmingly high. Preventive treatment is pivotal to avoid the numerous complications associated with diabetic ulcerations. However, at the onset of ulceration, early treatment under the supervision and guidance of a specialist can result in remission. Diabetic peripheral neuropathy is also a life-altering and debilitating disease. Although some patients experience numbness, some experience pain that can be sharp, shooting, and tingling. Although treatment is challenging and often requires medication, newer modalities, such as stimulation and physical therapy, have shown promise in reversing the devastating effects of peripheral neuropathy.

Hyperbaric and topical oxygen therapies in thermal burn wound healing: a review

OBJECTIVE

This review aims to evaluate the effectiveness of the two most commonly used oxygen delivery methods for the treatment of thermal burn wound healing: hyperbaric oxygen therapy (HBOT) and topical oxygen therapy (TOT).

METHOD

The PubMed database was searched for articles discussing the use of HBOT or TOT in the treatment of thermal burns.

RESULTS

The search yielded 43,406 articles, of which 28 (23 HBOT, 5 TOT) met the inclusion criteria. Both experimental and clinical studies have demonstrated conflicting results after treating thermal burns with HBOT or TOT. Overall, 14/23 studies demonstrated positive results for HBOT on the healing of burn wounds and associated complications, such as oedema and pain. Findings from these studies showed it can reduce morbidity and mortality in certain high-risk groups such as those with diabetes or extensive burns. Although the five studies (one human and four animal trials) reviewing TOT showed promising outcomes, this therapeutic modality has not been well investigated.

CONCLUSION

Therapeutic use of HBOT in thermal burns has been popular in the past but its use remains controversial due to inconsistent results, serious side-effects, lack of convenience and high costs. The use of TOT in the management of burns needs further exploration by scientists and clinicians alike, in addition to the implementation of a standardised treatment protocol.

Challenges of Gene Editing Therapies for Genodermatoses

Genodermatoses encompass a wide range of inherited skin diseases, many of which are monogenic. Genodermatoses range in severity and result in early-onset cancers or life-threatening damage to the skin, and there are few curative options. As such, there is a clinical need for single-intervention treatments with curative potential. Here, we discuss the nascent field of gene editing for the treatment of genodermatoses, exploring CRISPR-Cas9 and homology-directed repair, base editing, and prime editing tools for correcting pathogenic mutations. We specifically focus on the optimisation of editing efficiency, the minimisation off-targets edits, and the tools for delivery for potential future therapies. Honing each of these factors is essential for translating gene editing therapies into the clinical setting. Therefore, the aim of this review article is to raise important considerations for investigators aiming to develop gene editing approaches for genodermatoses.

Application expansion of small intestinal submucosa extracellular matrix in complex and surgical wounds

A wound is hard-to-heal or complex when the defect fails to progress through the normal stages of wound healing in a timely fashion. Hard-to-heal wounds such as diabetic foot or venous leg ulcers can be long-lasting conditions. Alternatively, complex acute wounds that occur from trauma, burns, postoperative, necrosis and some dermatological diseases can also result in hard-to-heal wounds. This article reviews important considerations in the management of complex acute wounds, such as time to wound closure, pain, scarring, patient satisfaction and identification of options that can promote healing of grafts and flaps, while reducing donor-site morbidity. Primary research has demonstrated the inherent benefits of small intestinal submucosa extracellular matrix (SIS-ECM), a naturally occurring porcine matrix that promotes development of dermis-like tissue in both complex acute and hard-to-heal wounds. Presently, the literature provides mostly case studies demonstrating the benefits of SIS-ECM in the management of complex acute wounds. The available case series suggest emerging clinical benefits including rapid time to coverage, avoidance of donor-site complications and development of granulation tissue in locations of low circulation, which improves poor graft sites, potentially reducing dehiscence and providing support for reconstruction flaps and grafts.

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.

Individually moulded silicone dressing in full thickness skin grafts

Background

Full thickness skin grafting is a common technique for reconstructing defects in the head and neck area. We propose the use of an addition-cured silicone as an individually moulded silicone dressing to keep the vulnerable skin graft in place, prevent shearing forces and create a moist environment.

Method

The silicone dressing is applied directly on the graft, using a double cartridge system. The silicone is moulded to the skin graft and hardens quickly, integrating thread knots into its material and creating good adherence to the graft. Charts of 24 patients who had undergone reconstruction with full thickness skin graft from the neck after surgery for skin tumors in the head from November 2017 to October 2020, were reviewed retrospectively to quantify the degree of post-operative graft loss and durability of the dressing.

Conclusion

Medical silicone based on venylpolysiloxane is a safe and durable dressing which makes postoperative dressing changes expendable.

Trial registration The study was approved by the institutional review board of the Brandenburg state medical association (S 4(bB)/2021).

Graphical Abstract

Electrospun Nanofibers for Wound Management

Electrospun nanofibers show great potential in biomedical applications. This mini review article traces the recent advances in electrospun nanofibers for wound management via various approaches. Initially, we provide a short note on the four phases of wound healing, including hemostasis, inflammation, proliferation, and remodeling. Then, we state how the nanofiber dressings can stop bleeding and reduce the pain. Following that, we discuss the delivery of therapeutics and cells using different types of nanofibers for enhancing cell migration, angiogenesis, and re-epithelialization, resulting in the promotion of wound healing. Finally, we present the conclusions and future perspectives regarding the use of electrospun nanofibers for wound management.

Identification of Angiogenic Cargoes in Human Fibroblasts-Derived Extracellular Vesicles and Induction of Wound Healing

A complete redevelopment of the skin remains a challenge in the management of acute and chronic wounds. Recently, the application of extracellular vesicles (EVs) for soft tissue wound healing has received much attention. As fibroblasts are fundamental cells for soft tissues and skin, we investigate the proangiogenic factors in human normal fibroblast-derived EVs (hNF-EVs) and their effects on wound healing. Normal fibroblasts were isolated from human skin tissues and characterized by immunofluorescence (IF) and Western blotting (WB). hNF-EVs were isolated by ultracentrifugation and characterized using transmission electron microscopy and WB. The proangiogenic cargos in hNF-EVs were identified by a TaqMan assay and a protein array. Other in vitro assays, including internalization assays, cell counting kit-8 analysis, scratch wound assays, WBs, and tube formation assays were conducted to assess the effects of hNF-EVs on fibroblasts and endothelial cells. A novel scaffold-free noninvasive delivery of hNF-EVs with or without fibrin glue was applied onto full-thickness skin wounds in mice. The wound healing therapeutical effect of hNF-EVs was assessed by calculating the rate of wound closure and through histological analysis. Isolated hNF was confirmed by verifying the expression of the fibroblast markers vimentin, αSMA, Hsp70, and S100A4. Isolated hNF-EVs showed intact EVs with round morphology, enriched in CD81 and CD63, and devoid of the cell markers GM130, Calnexin, and Cytochrome C. Our TaqMan assay showed that hNF-EVs were enriched in miR130a and miR210, and protein arrays showed enriched levels of the proangiogenic proteins’ vascular endothelial growth factor (VEGF)-D and CXCL8. Next, we found that the internalization of hNF-EVs into hNF increased the proliferation and migration of hNF, in addition to increasing the expression of bFGF, MMP2, and αSMA. The internalization of hNF-EVs into the endothelial cells increased their proliferation and tube formation. A scaffold-free noninvasive delivery of hNF-EVs with or without fibrin glue accelerated the wound healing rate in full-thickness skin wounds in mice, and the treatments increased the cellular density, deposition, and maturation of collagens in the wounds. Moreover, the scaffold-free noninvasive delivery of hNF-EVs with or without fibrin glue increased the VEGF and CD31 expression in the wounds, indicating that hNF-EVs have an angiogenic ability to achieve complete skin regeneration. These findings open up for new treatment strategies to be developed for wound healing. Further, we offer a new approach to the efficient, scaffold-free noninvasive delivery of hNF-EVs to wounds.

Strategies to Induce Blood Vessel Ingrowth into Skin Grafts and Tissue-Engineered Substitutes

Skin is a multilayer organ consisting of several tissues and appendages residing in a complex niche. Adequate and physiologically regulated vascularization is an absolute requirement for skin homeostasis, regeneration, and wound healing. The lack of vascular networks and ischemia results in delayed wound closure. In addition, vascularization is critical for the prolonged function and survival of skin grafts and tissue-engineered skin substitutes. This study highlights the clinical challenges associated with the limited vascularization in the cutaneous wounds. Then, we highlight the novel approaches for the development of vascular networks in the skin autografts, allografts, and artificial substitutes. Also, the future directions to overcome the existing vascularization complications in skin grafting and synthetic skin substitutes are presented. Statement of Significance Delayed closure of large dermal wounds, such as burn injuries, results from the lack of vascular networks and ischemia. The amount of blood supply in the skin graft is the primary factor determining the quality of the transplanted grafts. The current skin grafts and their fabrication methods lack the appropriate features that contribute to the vascularization and integration of the wound bed and graft and adherence to the skin layers. Therefore, the new generation of skin grafts should consider advanced technologies to induce vascularization and overcome current challenges.

Bioprinted Gelatin-Recombinant Type III Collagen Hydrogel Promotes Wound Healing

Artificial skins are biomaterials that can replace the lost skin or promote the regeneration of damaged skin. Skin regenerative biomaterials are highly applauded because they can exempt patients with severe burns from the painful procedure of autologous skin transplantation. Notwithstanding decades of research, biocompatible, degradable, and printable biomaterials that can effectively promote skin regeneration as a transplantation replacement in clinical use are still scarce. Here, we report one type of all-protein hydrogel material as the product of the enzymatic crosslinking reaction of gelatin and a recombinant type III collagen (rColIII) protein. Doping the rColIII protein in gelatin reduces the inflammatory response as an implant underneath the skin. The all-protein hydrogel can be bioprinted as scaffolds to support the growth and proliferation of 3T3 fibroblast cells. The hydrogel used as a wound dressing promotes wound healing in a rat model of skin damage, showing a faster and healthier recovery than the controls. The rColIII protein in the hydrogel has been shown to play a critical role in skin regeneration. Altogether, this work manifests the development of all-protein gelatin-rColIII hydrogel and demonstrates its use in wound healing. The gelatin-collagen hydrogel wound dressing thereby may become a promising treatment of severe wounds in the future.

Chitosan/Gelatin Composite Nonwoven Fabric Scaffold Seeding Minimal Function Unit of Skin for Functional Skin Regeneration

The construction of intact functional skin is a challenging field in tissue engineering. Traditional skin tissue engineering, using "seed cells" as a bioactive source for scaffolding materials maybe not efficient enough. Here a new strategy is shown for constructing functional tissue-engineered skin with Minimal Functional Unit of Skin (MFUS) as the source of bioactivity. Chitosan/gelatin non-woven fabric is used as the scaffold. MFUS is derived from autologous skin with full-thickness skin microstructure and complete functional skin unit harvesting. A mathematical model is used to calculate the MFUS Minimal Harvest Diameter and Angle (MHDA). Chitosan/gelatin non-woven fabric (CS+GEL) is porous and absorbable, with an elastic modulus meeting the requirement of skin engineering. It supports layered and 3D growth of MFUS. The degradation rate of chitosan, including filament diameter and density is evaluated in vivo. MFUS-engineered skin could reduce the density of local nerve fibers in the early stage, potentially reducing pain during wound healing, as well as could limit excessive fibroblast cell migration in the later stage, potentially reducing scar formation. This study proposes a new strategy for the clinical treatment of large full-thickness skin defects by constructing intact functional at minimal cost.

Skin biomechanics: a potential therapeutic intervention target to reduce scarring

Pathological scarring imposes a major clinical and social burden worldwide. Human cutaneous wounds are responsive to mechanical forces and convert mechanical cues to biochemical signals that eventually promote scarring. To understand the mechanotransduction pathways in cutaneous scarring and develop new mechanotherapy approaches to achieve optimal scarring, the current study highlights the mechanical behavior of unwounded and scarred skin as well as intra- and extracellular mechanisms behind keloid and hypertrophic scars. Additionally, the therapeutic interventions that promote optimal scar healing by mechanical means at the molecular, cellular or tissue level are extensively reviewed. The current literature highlights the significant role of fibroblasts in wound contraction and scar formation via differentiation into myofibroblasts. Thus, understanding myofibroblasts and their responses to mechanical loading allows the development of new scar therapeutics. A review of the current clinical and preclinical studies suggests that existing treatment strategies only reduce scarring on a small scale after wound closure and result in poor functional and aesthetic outcomes. Therefore, the perspective of mechanotherapies needs to consider the application of both mechanical forces and biochemical cues to achieve optimal scarring. Moreover, early intervention is critical in wound management; thus, mechanoregulation should be conducted during the healing process to avoid scar maturation. Future studies should either consider combining mechanical loading (pressure) therapies with tension offloading approaches for scar management or developing more effective early therapies based on contraction-blocking biomaterials for the prevention of pathological scarring.

Utilization of Acupuncture and Herbal Ointment Instead of Skin Graft Surgery for the Treatment of Burn Injuries: A Case Series and Literature review

Skin graft surgery is a standard treatment that increases the survival rate of patients with burn injuries; however, it leaves many sequelae. Conventional external preparations for the treatment of burns also have various side effects. In this retrospective case study, we assessed the cases of four patients with topical third-degree burns who did not wish to undergo the skin graft surgeries recommended by medical doctors and were thus treated using traditional medicine alone. A Korean medicine doctor administered integrative traditional medicine treatment to the patients using acupuncture and herbal ointments. Analysis of the patients' treatment photographs, quantitative evaluation indices, and vivid narratives suggested that their skin recovered well without adverse effects. Traditional Korean medicine treatment, including acupuncture and herbal ointment treatment, can be a new alternative therapeutic strategy for the treatment of patients with topical burns who do not want to undergo skin graft surgery or who have higher risks for poor surgical outcomes.

Lower Extremity Ulcers

Lower extremity ulcerations contribute to significant morbidity and economic burden globally. Chronic wounds, or those that do not progress through healing in a timely manner, are estimated to affect 6.5 million people in the United States alone causing, significant morbidity and economic burden of at least an estimated $25 billion annually. Owing to the aging population and increasing rates of obesity and diabetes mellitus globally, chronic lower extremity ulcers are predicted to increase. Here, we explore the pathophysiology, diagnosis, and management of the most (and least) commonly seen lower extremity ulcers.

Novel silicone dressing in full thickness skin grafts - A retrospective controlled case series

PURPOSE

The right choice of dressing after skin grafting, especially in the anatomically complex and aesthetically important head and neck area, is difficult. It is important to have a dressing which is durable and doesn't need a lot of dressing changes. This study introduces a novel, individually moulded silicon dressing; and investigates the number of dressing changes, durability of the dressing and the aesthetic outcome of patients receiving this new type of dressing, in comparison to a control group.

MATERIALS AND METHODS

The present retrospective single center controlled case series study reports our experiences using two different types of dressing on patients undergoing full thickness skin grafts in the head during the period 01 May 2016 to 01 May 2020. Data were analysed according to the type of dressing with either a transparent moulded silicone dressing or an established silicone sheet dressing.

RESULTS

52 patients were included in the study. We found no difference in the aesthetic outcome and complication rate (p > 0.05) between the two groups. The number of days until first dressing change after surgery, the number of dressing changes or follow up visits in the outpatient care until complete wound healing, and the overall number of dressing changes were all statistically significantly reduced (p < 0.05).

CONCLUSION

Addition-cured silicone used as a moulded dressing in full thickness skin grafts has longer durability and leads to a significant reduction of dressing changes with equal aesthetic outcome compared to an establishes silicone sheet dressing.

Clinical study on a skin stretching technique with adjustable external fixators to treat skin defects

The aim of this study was to determine the effectiveness of a skin stretching technique with adjustable external fixators in treating skin defects.Eighteen patients treated with a skin-stretching technique with adjustable external fixators for skin defects from April 2017 to October 2019 were included. Visual Analogue Scale (VAS) scores were collected during therapy. The skin defects gradually became smaller until they were completely resolved according to the blood flow of the affected limb and wound skin (the color, temperature, elasticity, and capillary response). The defect sizes ranged from 4 cm × 2 cm to 20 cm × 6 cm.The 18 adjustable external fixators were dismantled in 2 to 9 days (mean, 4.05 days) after the operation, and the defects were completely closed and the sutures were removed after 2 to 3 weeks. The average VAS score was 5.97. The follow-up period was 4 to 12 months (mean, 6.3 months); 17 patients healed well with linear small scar, and no infections or patients of necrosis were observed. Sensory recovery was assessed using the Medical Research Council scale, and all the sensation scores were S3+. Eight patients were healed after the first stage. Nine patients were closed totally while small sinus or skin defect were observed after sutures were removed; 3 patients were healed after the second debridement, and 6 patients finally healed after the dressings were changed. Patellar osteomyelitis recurred in 1 patient who was transferred to the Orthopedic Department for further treatment, and a flap graft procedure was performed.The operation was simple and obviously reduced the course of the disease, the costs, and the damage to the donor site, and it is also significantly superior to skin graft or flap transplantation procedures in terms of the resulting skin sensation, color, texture, elasticity, and appearance.

Evaluation of Patients' Preferences for Skin Grafting in Plastic-Surgical Defect Coverage

BACKGROUND

Grafting split-thickness (STSGs) and full-thickness skin grafts (FTSGs) are common techniques to replace missing skin and to restore the skin barrier in burn, trauma and remaining skin defects after tumor resections. The defect coverage with skin grafts offer many advantages, but also disadvantages such as donor site morbidity like possible sensory disturbances, scarring, risk of infection, contour changes and pigment disorders. We aimed to assess the preferred distribution of donor site for STSGs and FTSGs in patient’s skin grafting for plastic-surgical defect coverage.

METHODS

Patients and their accompany persons referred to the Department of Plastic Surgery were interviewed for defect coverage with STSGs or FTSGs, the preference in donor site was investigated and the detailed advantages and disadvantages were clarified.

RESULTS

We evaluated 85 participants (male=43, female=42) with a median age of 42 years (mean=46 years). The definition of the donor site (n=188 markings) was mainly based on the physicians recommendation (32.98%), mobility (23.40%), aesthetic results (22.34%) and pain (21.28%). Feared complications (n=152) were mainly wound healing disorders (32.24%), circulation disorders (28.29%), scars (20.39%) and bleeding risks (19.08%). Among all participants, 79 split-skin graft preferences were specified, while 32% favored the scalp as a donor site, as well as 29% the frontal part of the left thigh and 10% the frontal part of the right thigh.

CONCLUSION

There were preferred anatomical donor sites for skin grafting. Nevertheless, in conscious patients, the donor site has to be selected in a consent talk and joint approval, preoperatively. The options of taking STSGs from the occipital region with all its advantages should be discussed intensively as it is an attractive graft donor site.

Artificial dermal substitutes for tissue regeneration: comparison of the clinical outcomes and histological findings of two templates

OBJECTIVE

Artificial dermal substitutes (DSs) are fundamental in physiological wound healing to ensure consistent and enduring wound closure and provide a suitable scaffold to repair tissue. We compared the clinical and histological features of two DSs, Pelnac and Integra, in the treatment of traumatic and iatrogenic skin defects.

METHODS

This prospective observational study involved 71 randomly selected patients from our hospital. Wound healing was analyzed using the Wound Surface Area Assessment, the Vancouver Scar Scale, and a visual analog scale. Histological and immunohistochemical evaluations were also performed.

RESULTS

At 2 weeks, greater regeneration with respect to proliferation of the epidermis and renewal of the dermis was observed with Pelnac than with Integra. At 4 weeks, the dermis had regenerated with both DSs. Both templates induced renewed collagen and revascularization. Differences in the Vancouver Scar Scale score were statistically significant at 4 weeks and 1 year. Pelnac produced a significant increase in contraction at 2 weeks with increasing effectiveness at 4 weeks. Integra produced a higher percentage reduction in the wound surface area and a shorter healing time than Pelnac for wounds >1.5 cm deep.

CONCLUSION

Our observational data indicate that both DSs are effective and applicable in different clinical contexts.

Thin and Ultra-Thin Split-Thickness Skin Grafts Are Safe and Efficacious in the Burn Population

Split-thickness skin-grafts are a mainstay of burn management. Studies suggest no benefit to using thick (0.025 inch) over standard (0.012-0.020 inch) grafts, and some support the use of thin (0.008 inch) over standard thickness. Data on the use of even thinner grafts is scarce. This study reviewed outcomes of burn patients treated with thin (0.008-0.011 inch) and ultra-thin (≤0.007 inch) grafts. Retrospective review of records from July 2012 to June 2016 included patients who sustained operative burns treated by a single surgeon. Patients were excluded for nonoperative injuries, inhalational injuries, or prolonged hospitalizations. Outcome measures were compared between thin and ultra-thin groups. One-hundred twenty-eight patients met inclusion criteria; 35 received thin split-thickness skin-grafts while 93 received ultra-thin. Cohort analysis demonstrated equivalent graft-take, time to reepithelialization, and functional outcomes. Time to donor-site healing was significantly faster in the ultra-thin cohort (P = .04). Of those with functional outcomes recorded, 88.1% had good-excellent function and 11.9% retained a limitation in function as designated in physical therapy notes. There were fewer complications overall (P = .004) and a lower incidence of hypertrophic scarring (P = .025) in the ultra-thin cohort. This study presents a single-surgeon experience with thin and ultra-thin split-thickness skin-grafts. These grafts are exhibit excellent graft-take and few complications. There was no correlation between thickness and functional outcome at the time of physical therapy discharge. Donor-site reepithelialization was faster with ultra-thin grafts, which may be important in patients with large burns and limited donor sites.

Adipose-derived stem cells in wound healing of full-thickness skin defects: a review of the literature. J Plast Surg Hand Surg 2020;54:263-279. [PMID: 32427016 DOI: 10.1080/2000656x.2020.1767116]

The complex process of wound healing can be delayed in circumstances when the natural niche is extremely altered. Adipose-derived stem cells (ADSC) seem to be a promising therapy for these type of wounds. We aim to describe the studies that used ADSC for wound healing after a full-thickness skin defect, the ADSC mechanisms of action, and the outcomes of the different ADSC therapies applied to date. We performed a review by querying PubMed database for studies that evaluated the use of ADSC for wound healing. The Mesh terms, adipose stem cells AND (skin injury OR wound healing) and synonyms were used for the search. Our search recorded 312 articles. A total of 30 articles met the inclusion criteria. All were experimental in nature. ADSC was applied directly (5 [16.7%]), in sheets (2 [6.7%]), scaffolds (14 [46.7%]), skin grafts (3 [10%]), skin flaps (1 [3.3%]), as microvesicles or exosomes (4 [13.3%]), with adhesives for wound closure (1 [3.3%]), and in a concentrated conditioned hypoxia-preconditioned medium (1 [3.3%]). Most of the studies reported a benefit of ADSC and improvement of wound healing with all types of ADSC therapy. ADSC applied along with extracellular matrix, stromal cell-derived factor (SDF-1) or keratinocytes, or ADSC seeded in scaffolds showed better outcomes in wound healing than ADSC alone. ADSC have shown to promote angiogenesis, fibroblast migration, and up-regulation of macrophages chemotaxis to enhance the wound healing process. Further studies should be conducted to assure the efficacy and safety of the different ADSC therapies.

Darier and Ferrand's dermatofibrosarcoma: A carcinologic and cosmetologic challenge in a low-income country

INTRODUCTION

Dermatofibrosarcoma (DFS) is a common dermic sarcoma. It is a local malignant tumor occurring in young adults. The recurrence potential justifies an R0-type surgery with a three centimeters margin. We report our experience of the management of locally advanced DFS by resection and reconstructive surgery.

METHODS

It is an ongoing descriptive study spanned from June 2005 to December 2018. We included all DFS cases treated by curative resection and reconstruction. A total of eight cases of DFS among 108 soft tissue sarcomas were studied. All patients were males. The mean age was 41.8 years [32-60]. Carcinologic results, cosmetic results, and outcomes were analyzed.

RESULTS

R0-type resection was performed in six cases. In two cases, the resection was R1-type and resulted in amputation. In four cases, it was an iterative surgery. Average desease duration was 4 years [1-8]. Reconstructive surgery was needed for wound closure in six cases. Wounds healed in 28 days [18-90]. Outcomes showed hyperchromic keloid scars (N=2) at the trunk localization.

CONCLUSION

DFS is a common cancer with a good outcome if managed earliest. Delayed diagnoses and inadequate first-time surgery led to tumor extension and recurrences. Locally advanced tumors management needs extensive resections and reconstructive surgery. In addition to surgery, Imatinib and radiotherapy improve outcomes, but are not available in our context.

Bioprinted Skin Recapitulates Normal Collagen Remodeling in Full-Thickness Wounds

Over 1 million burn injuries are treated annually in the United States, and current tissue engineered skin fails to meet the need for full-thickness replacement. Bioprinting technology has allowed fabrication of full-thickness skin and has demonstrated the ability to close full-thickness wounds. However, analysis of collagen remodeling in wounds treated with bioprinted skin has not been reported. The purpose of this study is to demonstrate the utility of bioprinted skin for epidermal barrier formation and normal collagen remodeling in full-thickness wounds. Human keratinocytes, melanocytes, fibroblasts, dermal microvascular endothelial cells, follicle dermal papilla cells, and adipocytes were suspended in fibrinogen bioink and bioprinted to form a tri-layer skin structure. Bioprinted skin was implanted onto 2.5 × 2.5 cm full-thickness excisional wounds on athymic mice, compared with wounds treated with hydrogel only or untreated wounds. Total wound closure, epithelialization, and contraction were quantified, and skin samples were harvested at 21 days for histology. Picrosirius red staining was used to quantify collagen fiber orientation, length, and width. Immunohistochemical (IHC) staining was performed to confirm epidermal barrier formation, dermal maturation, vascularity, and human cell integration. All bioprinted skin treated wounds closed by day 21, compared with open control wounds. Wound closure in bioprinted skin treated wounds was primarily due to epithelialization. In contrast, control hydrogel and untreated groups had sparse wound coverage and incomplete closure driven primarily by contraction. Picrosirius red staining confirmed a normal basket weave collagen organization in bioprinted skin-treated wounds compared with parallel collagen fibers in hydrogel only and untreated wounds. IHC staining at day 21 demonstrated the presence of human cells in the regenerated dermis, the formation of a stratified epidermis, dermal maturation, and blood vessel formation in bioprinted skin, none of which was present in control hydrogel treated wounds. Bioprinted skin accelerated full-thickness wound closure by promoting epidermal barrier formation, without increasing contraction. This healing process is associated with human cells from the bioprinted skin laying down a healthy, basket-weave collagen network. The remodeled skin is phenotypically similar to human skin and composed of a composite of graft and infiltrating host cells. Impact statement We have demonstrated the ability of bioprinted skin to enhance closure of full-thickness wounds through epithelialization and normal collagen remodeling. To our knowledge, this article is the first to quantify collagen remodeling by bioprinted skin in full-thickness wounds. Our methods and results can be used to guide further investigation of collagen remodeling by tissue engineered skin products to improve ongoing and future bioprinting skin studies. Ultimately, our skin bioprinting technology could translate into a new treatment for full-thickness wounds in human patients with the ability to recapitulate normal collagen remodeling in full-thickness wounds.

Biofabrication of thick vascularized neo-pedicle flaps for reconstructive surgery

Wound chronicity due to intrinsic and extrinsic factors perturbs adequate lesion closure and reestablishment of the protective skin barrier. Immediate and proper care of chronic wounds is necessary for a swift recovery and a reduction of patient vulnerability to infection. Advanced therapies supplemented with standard wound care procedures have been clinically implemented to restore aberrant tissue; however, these treatments are ineffective if local vasculature is too compromised to support minimally-invasive strategies. Autologous "flaps", which are tissues equipped with their own hierarchical vascular supply, can be harvested from one region of the patient and transplanted to the wound where it is reperfused upon microsurgical anastomosis to appropriate recipient vessels. Despite the success of autologous flap transfer, these procedures are extremely invasive, incur obligatory donor-site morbidity, and require sufficient donor-tissue availability, microsurgical expertise, and specialized equipment. 3D-bioprinting modalities, such as extrusion-based bioprinting, can be used to address the clinical constraints of autologous flap transfer, primarily addressing donor-site morbidity and tissue availability. This advancement in regenerative medicine allows the biofabrication of heterogeneous tissue structures with high shape fidelity and spatial resolution to generate biomimetic constructs with the anatomically-precise geometries of native tissue to ensure tissue-specific function. Yet, meaningful progress toward this clinical application has been limited by the lack of vascularization required to meet the nutrient and oxygen demands of clinically relevant tissue volumes. Thus, various criteria for the fabrication of functional tissues with hierarchical, patent vasculature must be considered when implementing 3D-bioprinting technologies for deep, chronic wounds.

Treating skin graft donor sites: a comparative study between remnant skin use and polyurethane foam

Objective:

Excess remnant skin is retained for use in additional grafting in case of split-thickness skin graft (STSG) failure. We hypothesise that regrafting with remnant skin offers greater efficacy and advantages in wound healing and donor site appearance.

Methods:

Skin graft donor sites were assessed by comparing those regrafted with remnant skin with those treated with polyurethane foam dressing. Healing time, pain, patient satisfaction, itching sensation, skin stiffness and irregularity between regrafting and foam dressing were compared. The aesthetic satisfaction of donor site was evaluated by four board-certified plastic surgeons. The differences were tested statistically.

Results:

A total of 39 patients received a STSG due to skin or soft tissue wounds caused by burn, trauma and cancer reconstruction. The donor site healing time was shorter with remnant skin regrafting compared with foam dressing. There was no difference with respect to donor site pain between the two treatment groups. At two weeks after skin graft, patient satisfaction was higher in those treated with remnant skin than in those treated with foam dressing. Aesthetic assessment was improved after 12 weeks.

Conclusion:

Donor site dressing using remnant skin appears to improve wound healing and enhance the aesthetic outcome of donor sites.

Evaluation of Donor Site Pain After Fractional Autologous Full-Thickness Skin Grafting

Background: Despite the development of numerous wound treatment alternatives, 25% to 50% of leg ulcers and >30% of foot ulcers are not fully healed after 6 months of treatment. Autologous skin grafting is a time-tested therapy for these wounds; however, the creation of a new wound in the donor area yields a considerable limitation to this procedure.

Innovation: Fractional autologous full-thickness skin grafting (FFTSG) is a technique wherein multiple small full-thickness skin grafts (FTSGs) are harvested with possibly minor donor-site comorbidities. The first device used to harvest FFTSG (ART™ system, Medline, Northfield, IL) is a device capable of harvesting >300 small FTSGs and transferring them to a target wound.

Objective: To better evaluate patients' clinical experience, we sought to evaluate pain at the donor site associated with this procedure.

Approach: Pain was assessed with numeric visual analog pain scales at days 1, 2, 4, and 7. Nine subjects underwent this procedure with only six of them reporting any level of pain on day 1, and none disclosing pain after day 2.

Conclusion: In this study, we evidenced that this device manages to harvest FTSGs with minimal associated pain. Future research will need to evaluate other aspects of the procedure as well as long-term outcomes at the donor and recipient areas.

Mechanical forces in skin disorders

Mechanical forces are known to regulate homeostasis of the skin and play a role in the pathogenesis of skin diseases. The epidermis consists of keratinocytes that are tightly adhered to each other by cell junctions. Defects in keratins or desmosomal/hemidesmosomal proteins lead to the attenuation of mechanical strength and formation of intraepidermal blisters in the case of epidermolysis bullosa simplex. The dermis is rich in extracellular matrix, especially collagen, and provides the majority of tensile force in the skin. Keloid and hypertrophic scar, which is the result of over-production of collagen by fibroblasts during the wound healing, are associated with extrinsic tensile forces and changes of intrinsic mechanical properties of the cell. Increasing evidences shows that stiffness of the skin environment determines the regenerative ability during wound healing process. Mechanotransduction pathways are also involved in the morphogenesis and cyclic growth of hair follicles. The development of androgenetic alopecia is correlated to tensile forces generated by the fibrous tissue underlying the scalp. Acral melanoma predominantly occurs in the weight-bearing area of the foot suggesting the role of mechanical stress. Increased dermal stiffness from fibrosis might be the cause of recessive dystrophic epidermolysis bullosa associated squamous cell carcinoma. Strategies to change the mechanical forces or modify the mechanotransduction signals may lead to a new way to treat skin diseases and promote skin regeneration.

Wound healing of cutaneous substance losses based on infectious, inflammatory and traumatic skin disorders: The experience of a center

INTRODUCTION

There is no reference available concerning the standard healing time based on dermatological diseases responsible for cutaneous substance losses. The aim of our study was to assess the healing time after surgical debridement of necrotizing fasciitis (NF), hidradenitis suppurativa (HS) and skin necrosis due to trauma (SNT) based on multiples existing co-morbidities among these patients to provide surgeons with accurate scientific data in order to inform and educate patients and nurses who are practicing care under the supervision of the surgeon.

MATERIALS AND METHODS

This was a retrospective study. The primary endpoint was the time for complete wound healing, which was calculated from the time of the last surgical procedure to the complete wound healing corresponding to the time of complete reepithelialization, when daily dressings were no longer needed.

RESULTS

A total of 107 patients were included. The mean time for complete wound healing was 64.94±31.55 days in patients with NF, 45.70±21.40 days in patients with SNT and 75.02±26.41 days in patients with HS (SNT versus NF, P=0.004** and SNT versus HS, P<0.0001**).

CONCLUSION

The mean time for complete wound healing was 64.94 days in patients with NF, 45.70 days in patients with SNT, 75.02 days in patients with HS. This study can be considered as a referential based on the experience of a reference centre for these 3 pathologies (NF, HS, and SNT) whose aim is to inform plastic surgeons in order to anticipate the management or educate the patient.

Epidermal Stem Cells in Skin Wound Healing

Significance: Skin serves as a protective barrier for mammals. Epidermal stem cells are responsible for maintaining skin homeostasis. When cutaneous injuries occur, skin homeostasis and integrity are damaged, leading to dire consequences such as acute, chronic, or infected wounds. Skin wound healing is an intrinsic self-saving chain reaction, which is crucial to facilitating the replacement of damaged or lost tissue. Recent Advances: An immense amount of research has uncovered the underlying mechanisms behind the complex and highly regulated wound healing process. In this review, we will dissect the biological process of adult skin wound healing and emphasize the importance of epidermal stem cells during the wound healing. Critical Issues: We will comprehensively discuss the current clinical practices used on patients with cutaneous wounds, including both traditional skin grafting procedures and advanced grafting techniques with cultured skin stem cells. The majority of these leading techniques still retain some deficiencies during clinical use. Moreover, the regeneration of skin appendages after severe injuries remains a challenge in treatment. Future Directions: Understanding epidermal stem cells and their essential functions during skin wound healing are fundamental components behind the development of clinical treatment on patients with cutaneous wounds. It is important to improve the current standard of care and to develop novel techniques improving patient outcomes and long-term rehabilitation, which should be the goals of future endeavors in the field of skin wound healing.

Transit-Amplifying Cells in the Fast Lane from Stem Cells towards Differentiation

Stem cells have a high potential to impact regenerative medicine. However, stem cells in adult tissues often proliferate at very slow rates. During development, stem cells may change first to a pluripotent and highly proliferative state, known as transit-amplifying cells. Recent advances in the identification and isolation of these undifferentiated and fast-dividing cells could bring new alternatives for cell-based transplants. The skin epidermis has been the target of necessary research about transit-amplifying cells; this work has mainly been performed in mammalian cells, but further work is being pursued in other vertebrate models, such as zebrafish. In this review, we present some insights about the molecular repertoire regulating the transition from stem cells to transit-amplifying cells or playing a role in the transitioning to fully differentiated cells, including gene expression profiles, cell cycle regulation, and cellular asymmetrical events. We also discuss the potential use of this knowledge in effective progenitor cell-based transplants in the treatment of skin injuries and chronic disease.