Chronological histological findings of cultured epidermal autograft over bilayer artificial dermis

Application of cultured epidermal autograft, JACE®, improves survival rate in extensive burns: A propensity score matching study using Tokyo registry data

Cultured epidermal autograft, JACE®, was introduced into the Japanese national health insurance system in 2009 and has been used in more than 1000 cases of extensive burns. The aim of this study was to investigate whether the use of JACE® contributes to survival rate in extensive burns. In this study, 119 cases were selected from 3990 cases in Tokyo Burn Unit Association registry data from 2009 to 2023, excluding cases with less than 40% total body surface area, cases of deaths within 4 weeks and cases with unknown length of hospital stay. In total, 25 patients treated with JACE® were selected and matched with another 25 patients who did not receive JACE® using propensity score matching. The results showed that patients treated with JACE® had a significantly higher survival rate than did those who were not treated with JACE® at all time points between 6 and 9 weeks post-injury. In addition, there was no significant difference in length of hospital stay between the groups. These results suggest that the use of JACE® in patients with extensive burns contributes to patient survival and does not prolong hospital stay.

Living Skin Substitute Tissue-Is a Replacement for the Autograft Possible?

The ideal living tissue skin substitute for use in burn injury does not yet exist. The currently available alternatives to autologous skin grafting require an understanding of their characteristics and limitations to make an informed decision of surgical treatment options. In this review, living tissue substitutes are categorized by autologous and allogeneic cell sources and epidermal-only versus bilayered tissue options. A short summary of the tissue composition, clinical data, and indications is provided. Finally, the gap in technology is defined and future potential areas of research are explored.

Efficacy of split-thickness skin graft combined with novel sheet-type reprocessed micronized acellular dermal matrix

BACKGROUND

Autologous split-thickness skin grafts (STSGs) remain the mainstay for treatment of large skin defects. Despite its many advantages, there exist critical disadvantages such as unfavorable scar and graft contracture. In addition, it cannot be used when structures such as tendons and bones are exposed. To overcome these limitations, acellular dermal matrix (ADM) is widely used with STSG. CGDerm Matrix^®, which was recently developed, is a novel reprocessed micronized ADM (RMADM). In this study, outcomes of the combined application of RMADM and STSG on full-thickness wounds were analyzed.

METHODS

Forty-one patients with full-thickness skin defects due to trauma, scar contracture release, and diabetic foot ulcers, who underwent STSGs, from January 2021 to July 2021, were retrospectively reviewed. The primary outcome of interest was skin loss rate, which was measured 14 days after surgery.

RESULTS

The most common cause of skin defect was trauma (36 patients), diabetic foot (2 patients), scar contracture release (2 patients), and malignancy (1 patient). The average defect size was 109.6 cm² (range, 8-450 cm²). The average skin loss rate was 9.1%, showing a graft take rate of > 90%.

CONCLUSION

The use of combined RMADM and STSG in full-thickness wound reconstruction provides stable and acceptable outcomes. The newly developed ADM can be a promising option in wound reconstruction.

Cellular and biological factors involved in healing wounds and burns and treatment options in tissue engineering

Severe traumatic wounds and burns have a high chance of mortality and can leave survivors with many functional disabilities and cosmetic problems, including scars. The healing process requires a harmonious interplay of various cells and growth factors. Different structures of the skin house numerous cells, matrix components and growth factors. Any disturbance in the balance between these components can impair the healing process. The function of cells and growth factors can be manipulated and facilitated to aid tissue repair. In the current review, the authors focus on the importance of the skin microenvironment, the pathophysiology of various types of burns, mechanisms and factors involved in skin repair and wound healing and regeneration of the skin using tissue engineering approaches.

Applications of electrospun scaffolds with enlarged pores in tissue engineering

Despite electrospinning has multiple advantages over other methods such as creating materials with superfine fiber diameter, high specific surface area, and good mechanical properties, the pore diameter of scaffolds prepared...

Using Various Skin Graft Techniques in Major Burn Reconstruction: A Lesson Learned From a Taiwanese Cornstarch Explosion

PURPOSE

Four hundred and ninety-nine patients had burn injuries in an explosion in Taiwan on June 27, 2015, 24 were admitted to the intensive care units of Taipei Veterans General Hospital. This study details our experience with surgical management of these patients, focusing primarily on various skin graft techniques.

MATERIALS AND METHODS

This single-center retrospective study included patients who underwent at least one of the previously mentioned skin graft techniques because of extensive skin defects. The demography, burn diagram, treatment modalities, postoperative outcome, and costs were all analyzed, and a comparison with traditional mesh skin grafts was performed. The literature was also reviewed.

RESULTS

Fourteen patients underwent the Meek skin graft technique. Only 3 received ReCell and 1 cultured epithelial autograft (CEA) at separate time point. Overall, the autologous skin grafts, including Meek/ReCell/CEA were completed within 6 months. The average skin graft success rate was approximately 72.9%, 79.2%, and 38% in Meek, ReCell, and CEA, respectively. The infection rate was approximately 35.7%, 25%, and 100% in Meek, ReCell, and CEA, respectively. The average surgical cost and total medical cost were significantly higher in patients who underwent Meek/ReCell/CEA treatments.

CONCLUSIONS

In our experience, Meek and ReCell treatments had acceptable success rates, but CEA treatment not. ReCell and CEA treatments are useful in the event of extremely limited donor sites, and they are fragile, easily infected, and technically challenging. These techniques also require longer hospitalization and tend to be more expensive, all factors that should be considered when assessing treatment options.

The Human Epidermal Basement Membrane: A Shaped and Cell Instructive Platform That Aging Slowly Alters

One of the most important functions of skin is to act as a protective barrier. To fulfill this role, the structural integrity of the skin depends on the dermal-epidermal junction-a complex network of extracellular matrix macromolecules that connect the outer epidermal layer to the underlying dermis. This junction provides both a structural support to keratinocytes and a specific niche that mediates signals influencing their behavior. It displays a distinctive microarchitecture characterized by an undulating pattern, strengthening dermal-epidermal connectivity and crosstalk. The optimal stiffness arising from the overall molecular organization, together with characteristic anchoring complexes, keeps the dermis and epidermis layers extremely well connected and capable of proper epidermal renewal and regeneration. Due to intrinsic and extrinsic factors, a large number of structural and biological changes accompany skin aging. These changes progressively weaken the dermal-epidermal junction substructure and affect its functions, contributing to the gradual decline in overall skin physiology. Most changes involve reduced turnover or altered enzymatic or non-enzymatic post-translational modifications, compromising the mechanical properties of matrix components and cells. This review combines recent and older data on organization of the dermal-epidermal junction, its mechanical properties and role in mechanotransduction, its involvement in regeneration, and its fate during the aging process.

Artificial Dermis Composite Tissue Flaps versus Traditional Prefabricated Flaps

OBJECTIVE

We compared the application of artificial dermis composite tissue flaps and traditional prefabricated flaps in a rat model of exposed bone and tendon injury.

METHODS

Sprague Dawley rats were randomly divided into two groups (n = 40 per group). Group A rats received artificial dermis composite tissue flaps and group B rats received traditional prefabricated flaps. Flap appearance, range of motion, degree of swelling, tissue histologic results, and imaging findings were compared between groups at 7, 14, 21, and 28 days.

RESULTS

There was no difference in flap appearance, range of motion, or degree of swelling between groups. However, blood perfusion of the artificial dermis composite tissue flap was better than that of the traditional prefabricated flap; the artificial dermis was also found to be thicker than the traditional prefabricated flap.

CONCLUSIONS

The artificial dermis composite tissue flap is an ideal method for repairing exposed bone and tendon, and it displays repair effects comparable with those of the traditional prefabricated flap and may be a better alternative.

Dermal regenerative matrix use in burn patients: A systematic review

BACKGROUND

Dermal regenerative matrices (DRMs) have been used for several decades in the treatment of acute and reconstructive burn injury. The objective of this study was to perform a systematic review of the literature to assess clinical outcomes and safety profile of DRMs in full-thickness burn injury.

METHODS

Comprehensive searches of MEDLINE, EMBASE, CINAHL, and Cochrane Library were performed from 1988 to 2017. Two independent reviewers completed preliminary and full-text screening of all articles. English-language articles reporting on DRM use in patients with full-thickness burn injury were included.

RESULTS

Literature search generated 914 unique articles. Following screening, 203 articles were assessed for eligibility, and 72 met inclusion criteria for analysis. DRM was applied to1084 patients (74% acute burns, 26% burn reconstruction). Of the twelve studies that described changes in ROM, significant improvement was observed in 95% of reconstructive patients. The most frequently treated reconstructive sites were the neck, hand/wrist, lower extremity, and axilla. Vancouver scar scale was used in eight studies and indicated a significant improvement in the scar quality with DRM. The overall complication rate was 13%, most commonly infection, graft loss, hematoma formation, and contracture.

CONCLUSIONS

Although variability in functional and cosmetic outcomes was observed, DRM demonstrates improvements in ROM and scar appearance without objective regression. Essential demographic data were lacking in many studies, highlighting the need for future standardization of reporting outcomes in burns following application of dermal substitutes.

Keratinocyte sheets prepared with temperature-responsive dishes show enhanced survival after in vivo grafting on acellular dermal matrices in a rat model of staged bi-layered skin reconstruction

Introduction

Bi-layered skin reconstruction can be achieved by staged grafting of acellular dermal matrices (ADMs) and cultured epithelial keratinocyte sheets (KSs). Both KSs and ADMs have been used for long; yet, their combined use has shown poor effectiveness. This outcome has been related to the enzymatic treatment used in the preparation of KSs, which impairs their adhesion potential to ADMs and the formation of a basement membrane (BM). Temperature-responsive (TR) culture dishes allow for enzyme-free preparation of KSs with preservation of BMs and intercellular adhesion proteins; yet, their use has not been previously applied to staged bi-layered skin reconstruction. Using an in vivo rat model, we tested the hypothesis that TR cultures enhance KSs survival and BM preservation after sequential grafting on ADMs.

Methods

In nude rats (n = 9/group), a 9-cm [2] full-thickness dorsal skin defect was repaired with a commercial ADM. At 2 weeks after surgery, we grafted the ADM with KSs (circular, 25 mm diameter), prepared from human cells either by enzymatic Dispase treatment (DT control group) or a TR culture dish (TR experimental group). KSs survival and BMs preservation was assessed one week later by digital imaging, histology (hematoxylin & eosin), immunohistochemistry (collagen IV, pancytokeratins) and immunofluorescence (cytokeratin 1-5-6, laminin).

Results

The TR group showed a significantly higher KSs survival (120 ± 49 vs. 63 ± 42 mm²; p < 0.05) and epidermal thickness (165 ± 79 vs. 65 ± 54 μm; p < 0.01) compared with the control DT group, as well as higher epidermal maturation (cytokeratin) and a denser laminin and Collagen IV expression in the BMs in vitro and in vivo.

Conclusion

These findings suggest that KSs prepared with TR culture dishes have significantly enhanced survival when grafted on ADMs; these outcomes could help improve current clinical strategies in wound care by skin reconstruction.

Effect of Mature Adipocyte-Derived Dedifferentiated Fat Cells on Formation of Basement Membrane after Cultured Epithelial Autograft on Artificial Dermis

BACKGROUND

Artificial dermis is an important option for preparing full-thickness wounds for cultured epithelial autografting. Long-term fragility after cultured epithelial autografting remains a problem, probably because of the lack of basement membrane proteins. The authors hypothesized that treating artificial dermis with mesenchymal stem cells would promote basement membrane protein production. The authors tested this using dedifferentiated fat cells in a porcine experimental model.

METHODS

This study used four male crossbred (Landrace, Large White, and Duroc) swine. Cultured epithelium and dedifferentiated fat cells were prepared from skin and subcutaneous fat tissue harvested from the cervical region. Full-thickness open dorsal wounds were created and treated with artificial dermis to prepare a graft bed for cultured epithelial autograft. Two groups were established: the control group (artificial dermis treated with 0.5 ml of normal saline solution applied to the wounds) and the dedifferentiated fat group (artificial dermis treated with 0.5 × 10 dedifferentiated fat cells suspended in 0.5 ml of normal saline solution sprayed onto the wounds). On postoperative day 10, the prepared cultured epithelium was grafted onto the generated dermis-like tissue. Fourteen days later, tissue specimens were harvested and evaluated histologically.

RESULTS

Light microscopy of hematoxylin and eosin-stained sections revealed the beginning of rete ridge formation in the dedifferentiated fat group. Synthesis of both collagen IV and laminin-5 was significantly enhanced in the dedifferentiated fat group. Transmission electron microscopy revealed a nearly mature basement membrane, including anchoring fibrils in the dedifferentiated fat group.

CONCLUSION

Combined use of artificial dermis and dedifferentiated fat cells promotes post-cultured epithelial autograft production and deposition of basement membrane proteins at the dermal-epidermal junction and basement membrane development, including anchoring fibrils.

Advancements in Regenerative Strategies Through the Continuum of Burn Care

Burns are caused by several mechanisms including flame, scald, chemical, electrical, and ionizing and non-ionizing radiation. Approximately half a million burn cases are registered annually, of which 40 thousand patients are hospitalized and receive definitive treatment. Burn care is very resource intensive as the treatment regimens and length of hospitalization are substantial. Burn wounds are classified based on depth as superficial (first degree), partial-thickness (second degree), or full-thickness (third degree), which determines the treatment necessary for successful healing. The goal of burn wound care is to fully restore the barrier function of the tissue as quickly as possible while minimizing infection, scarring, and contracture. The aim of this review is to highlight how tissue engineering and regenerative medicine strategies are being used to address the unique challenges of burn wound healing and define the current gaps in care for both partial- and full-thickness burn injuries. This review will present the current standard of care (SOC) and provide information on various treatment options that have been tested pre-clinically or are currently in clinical trials. Due to the complexity of burn wound healing compared to other skin injuries, burn specific treatment regimens must be developed. Recently, tissue engineering and regenerative medicine strategies have been developed to improve skin regeneration that can restore normal skin physiology and limit adverse outcomes, such as infection, delayed re-epithelialization, and scarring. Our emphasis will be centered on how current clinical and pre-clinical research of pharmacological agents, biomaterials, and cellular-based therapies can be applied throughout the continuum of burn care by targeting the stages of wound healing: hemostasis, inflammation, cell proliferation, and matrix remodeling.

Cell therapy for severe burn wound healing

Cell therapy has emerged as an important component of life-saving procedures in treating burns. Over past decades, advances in stem cells and regenerative medicine have offered exciting opportunities of developing cell-based alternatives and demonstrated the potential and feasibility of various stem cells for burn wound healing. However, there are still scientific and technical issues that should be resolved to facilitate the full potential of the cellular devices. More evidence from large, randomly controlled trials is also needed to understand the clinical impact of cell therapy in burns. This article aims to provide an up-to-date review of the research development and clinical applications of cell therapies in burn wound healing and skin regeneration.

Pathophysiologic Mechanisms and Current Treatments for Cutaneous Sequelae of Burn Wounds

Burn injuries are a pervasive clinical problem. Extensive thermal trauma can be life-threatening or result in long-lasting complications, generating a significant impact on quality of life for patients as well as a cost burden to the healthcare system. The importance of addressing global or systemic issues such as resuscitation and management of inhalation injuries is not disputed but is beyond the scope of this review, which focuses on cutaneous pathophysiologic mechanisms for current treatments, both in the acute and long-term settings. Pathophysiological mechanisms of burn progression and wound healing are mediated by highly complex cascades of cellular and biochemical events, which become dysregulated in slow-healing wounds such as burns. Burns can result in fibroproliferative scarring, skin contractures, or chronic wounds that take weeks or months to heal. Burn injuries are highly individualized owing to wound-specific differences such as burn depth and surface area, in addition to patient-specific factors including genetics, immune competency, and age. Other extrinsic complications such as microbial infection can complicate wound healing, resulting in prolonged inflammation and delayed re-epithelialization. Although mortality is decreasing with advancements in burn care, morbidity from postburn deformities continues to be a challenge. Optimizing specialized acute care and late burn outcome intervention on a patient-by-patient basis is critical for successful management of burn wounds and the associated pathological scar outcome. Understanding the fundamentals of integument physiology and the cellular processes involved in wound healing is essential for designing effective treatment strategies for burn wound care as well as development of future therapies. Published 2018. Compr Physiol 8:371-405, 2018.

The Alteration of the Epidermal Basement Membrane Complex of Human Nevus Tissue and Keratinocyte Attachment after High Hydrostatic Pressurization

We previously reported that human nevus tissue was inactivated after high hydrostatic pressure (HHP) higher than 200 MPa and that human cultured epidermis (hCE) engrafted on the pressurized nevus at 200 MPa but not at 1000 MPa. In this study, we explore the changes to the epidermal basement membrane in detail and elucidate the cause of the difference in hCE engraftment. Nevus specimens of 8 mm in diameter were divided into five groups (control and 100, 200, 500, and 1000 MPa). Immediately after HHP, immunohistochemical staining was performed to detect the presence of laminin-332 and type VII collagen, and the specimens were observed by transmission electron microscopy (TEM). hCE was placed on the pressurized nevus specimens in the 200, 500, and 1000 MPa groups and implanted into the subcutis of nude mice; the specimens were harvested at 14 days after implantation. Then, human keratinocytes were seeded on the pressurized nevus and the attachment was evaluated. The immunohistochemical staining results revealed that the control and 100 MPa, 200 MPa, and 500 MPa groups were positive for type VII collagen and laminin-332 immediately after HHP. TEM showed that, in all of the groups, the lamina densa existed; however, anchoring fibrils were not clearly observed in the 500 or 1000 MPa groups. Although the hCE took in the 200 and 500 MPa groups, keratinocyte attachment was only confirmed in the 200 MPa group. This result indicates that HHP at 200 MPa is preferable for inactivating nevus tissue to allow its reuse for skin reconstruction in the clinical setting.

Application of the cultured epidermal autograft "JACE(®") for treatment of severe burns: Results of a 6-year multicenter surveillance in Japan

BACKGROUND

In the 1970s, Green et al. developed a method that involved culturing keratinocyte sheets and used for treatment of burns. Since then, the take rate of cultured epidermal autograft (CEA) onto fascia, granulation tissue, or allografts has been extensively reported, while that on an artificial dermis in a large case series is not. Moreover, the contribution of CEA to patient survival has not been analyzed in a multicenter study.

METHODS

We conducted a 6-year multicenter surveillance on the application of the CEA "JACE(®") for treatment of burns >30% total body surface area (TBSA) across 118 Japanese hospitals. This surveillance included 216 patients and 718 graft sites for efficacy analysis. The CEA take rate at 4 weeks after grafting was evaluated, and safety was monitored until 52 weeks. In addition, the survival curve obtained in this study and the data obtained from the Tokyo Burn Unit Association (TBUA) were compared.

RESULTS

The mean CEA take rates at week 4 were 66% (sites) and 68% (patients), and the rate on the artificial dermis was 65% for 226 sites. CEA application combined with wide split-thickness auto or patch autograft increased the CEA take rate. On comparison with the data obtained from the TBUA, which included data on individuals with burns of the same severity, CEA application was found to contribute to patient survival until 7 weeks after burn.

CONCLUSIONS

We reported the take rate of CEA based on a 6-year multicenter surveillance. From our results, we found that the application of CEA is a useful treatment for the patients with extensive burns.

Bioengineering a human plasma-based epidermal substitute with efficient grafting capacity and high content in clonogenic cells

Cultured epithelial autografts (CEAs) produced from a small, healthy skin biopsy represent a lifesaving surgical technique in cases of full-thickness skin burn covering >50% of total body surface area. CEAs also present numerous drawbacks, among them the use of animal proteins and cells, the high fragility of keratinocyte sheets, and the immaturity of the dermal-epidermal junction, leading to heavy cosmetic and functional sequelae. To overcome these weaknesses, we developed a human plasma-based epidermal substitute (hPBES) for epidermal coverage in cases of massive burn, as an alternative to traditional CEA, and set up critical quality controls for preclinical and clinical studies. In this study, phenotypical analyses in conjunction with functional assays (clonal analysis, long-term culture, or in vivo graft) showed that our new substitute fulfills the biological requirements for epidermal regeneration. hPBES keratinocytes showed high potential for cell proliferation and subsequent differentiation similar to healthy skin compared with a well-known reference material, as ascertained by a combination of quality controls. This work highlights the importance of integrating relevant multiparameter quality controls into the bioengineering of new skin substitutes before they reach clinical development.

SIGNIFICANCE

This work involves the development of a new bioengineered epidermal substitute with pertinent functional quality controls. The novelty of this work is based on this quality approach.

Acellular Dermal Matrix to Treat Full Thickness Skin Defects: Follow-Up Subjective and Objective Skin Quality Assessments

Background

There are several options for replacement of the dermal layer in full-thickness skin defects. In this study, we present the surgical outcomes of reconstruction using acellular dermal substitutes by means of objective and subjective scar assessment tools.

Methods

We retrospectively reviewed the medical records of 78 patients who had undergone autologous split-thickness skin graft with or without concomitant acellular dermal matrix (CGDerm or AlloDerm) graft. We examined graft survival rate and evaluated postoperative functional skin values. Individual comparisons were performed between the area of skin graft and the surrounding normal skin. Nine months after surgery, we compared the skin qualities of CGDerm graft group (n=25), AlloDerm graft group (n=8) with skin graft only group (n=23) each other using the objective and subjective measurements.

Results

The average of graft survival rate was 93% for CGDerm group, 92% for AlloDerm group and 86% for skin graft only group. Comparing CGDerm grafted skin to the surrounding normal skin, mean elasticity, hydration, and skin barrier values were 87%, 86%, and 82%, respectively. AlloDerm grafted skin values were 84%, 85%, and 84%, respectively. There were no statistical differences between the CGDerm and AlloDerm groups with regard to graft survival rate and skin functional analysis values. However, both groups showed more improvement of skin quality than skin graft only group.

Conclusion

The new dermal substitute (CGDerm) demonstrated comparable results with regard to elasticity, humidification, and skin barrier effect when compared with conventional dermal substitute (AlloDerm).