Characterisation of the cell suspension harvested from the dermal epidermal junction using a ReCell® kit

Wound Healing and Scar Patterning After Addition of Autologous Skin Cell Suspension to Meshed Grafts

INTRODUCTION

A common treatment for large deep-to-full-thickness burns is excision and grafting with a widely meshed split-thickness skin graft (mSTSG). Due to the differential healing of the interstices and adhered split-thickness skin graft, wound patterning and delayed wound healing are common outcomes of this treatment. Delayed healing may increase infection rates and wound care requirements, while wound patterning may be psychologically and aesthetically consequential for patients. Autologous skin cell suspension (ASCS) can be used to "over spray" a meshed autograft. It was hypothesized that the use of ASCS combined with mSTSG would increase the rate of wound healing and decrease patterning in healed burn wounds.

METHODS

Full-thickness burns or excisional wounds (n = 8 each) were created in red Duroc pigs and received 4:1 mSTSGs after wound bed preparation. Half of the wounds received ASCS and half did not at the time of grafting. Percent re-epithelialization, patterning, rete ridge ratio, cellularity, dermal and epidermal thickness, immunofluorescent S100β staining, and melanin index were assessed for each scar.

RESULTS

Wounds that received ASCS exhibited increased rates of re-epithelialization (burn +ACSC versus burn-ASCS; day 3 (53.9 ± 3.1 versus 34.3 ± 3.3, P = 0.009): day 5 (68.1 ± 1.6 versus 40.8 ± 3.2, P < 0.001)). Excision +ASCS versus excision-ASCS; day 7 (98.1 ± 1.2 versus 86.4 ± 2.0, day 7 P = 0.022) compared to wounds not treated with ASCS. There was no difference in rete ridge ratio, cellularity, dermal thickness, epidermal thickness, S100β staining, melanin index, or patterning was measured between wounds that received ASCS and those that did not.

CONCLUSIONS

The addition of ASCS to 4:1 mSTSGs leads to increased rate of wound healing but does not impact the degree of patterning in this model, suggesting that ASCS application likely robustly transfers keratinocytes but not functioning melanocytes at acute timepoints.

Advancements in cell-based therapies for thermal burn wounds: a comprehensive systematic review of clinical trials outcomes

BACKGROUND

Burn trauma is one of the major causes of morbidity and mortality worldwide. The standard management of burn wounds consists of early debridement, dressing changes, surgical management, and split-thickness skin autografts (STSGs). However, there are limitations for the standard management that inclines us to find alternative treatment approaches, such as innovative cell-based therapies. We aimed to systematically review the different aspects of cell-based treatment approaches for burn wounds in clinical trials.

METHODS

A systematic search through PubMed, Medline, Embase, and Cochrane Library databases was carried out using a combination of keywords, including "Cell transplantation", "Fibroblast", "Keratinocyte", "Melanocyte", or "Stem Cell" with "Burn", "Burn wound", or "Burn injury". Firstly, titles and abstracts of the studies existing in these databases until "February 2024" were screened. Then, the selected studies were read thoroughly, and considering the inclusion and exclusion criteria, final articles were included in this systematic review. Moreover, a manual search was performed through the reference lists of the included studies to minimize the risk of missing reports.

RESULTS

Overall, 30 clinical trials with 970 patients were included in our study. Considering the type of cells, six studies used keratinocytes, nine used fibroblasts, eight used combined keratinocytes and fibroblasts, one study used combined keratinocytes and melanocytes, five used combined keratinocytes and fibroblasts and melanocytes, and one study used mesenchymal stem cells (MSCs). Evaluation of the preparation type in these studies showed that cultured method was used in 25 trials, and non-cultured method in 5 trials. Also, the graft type of 17 trials was allogeneic, and of 13 other trials was autologous.

CONCLUSIONS

Our study showed that employing cell-based therapies for the treatment of burn wounds have significant results in clinical studies and are promising approaches that can be considered as alternative treatments in many cases. However, choosing appropriate cell-based treatment for each burn wound is essential and depends on the situation of each patient.

Benefits of Aerosolized, Point-of-care, Autologous Skin Cell Suspension (ASCS) for the Closure of Full-thickness Wounds From Thermal and Nonthermal Causes: Learning Curves From the First 50 Consecutive Cases at an Urban, Level 1 Trauma Center

OBJECTIVE

To determine the utility of Autologous Skin Cell Suspension (ASCS) in closing full-thickness (FT) defects from injury and infection.

BACKGROUND

Although ASCS has documented success in closing partial-thickness burns, far less is known about the efficacy of ASCS in FT defects.

METHODS

Fifty consecutive patients with FT defects (burn 17, necrotizing infection 13, crush 7, degloving 5, and other 8) underwent closure with the bilayer technique of 3:1 widely meshed, thin, split-thickness skin graft and 80:1 expanded ASCS. End points were limb salvage rate, donor site reduction, operative and hospital throughput, incidence of complications, and re-epithelialization by 4, 8, and 12 weeks.

RESULTS

Definitive wound closure was achieved in 76%, 94%, and 98% of patients, at 4, 8, and 12 weeks, respectively. Limb salvage occurred in 42/43 patients (10 upper and 33 lower extremities). The mean area grafted was 435 cm 2 ; donor site size was 212 cm 2 , representing a potential reduction of 50%. The mean surgical time was 71 minutes; the total operating room time was 124 minutes. The mean length of stay was 26.4 days; the time from grafting to discharge was 11.2 days. Four out of 50 patients (8%) required 6 reoperations for bleeding (1), breakdown (4), and amputation (1). Four out of 50 patients (8%) developed hypertrophic scarring, which responded to silicone sheeting (2) and laser resurfacing (2). The mean follow-up was 92.7 days.

CONCLUSIONS

When used for the closure of FT wounds, point-of-care ASCS is effective and safe. Benefits include rapid re-epithelialization, high rate of limb salvage, reduction of donor site size and morbidity, and low incidence of hypertrophic scarring.

Biological attributes required for epidermal regeneration: Evaluation of the next-generation autologous cell harvesting device

Early wound intervention and closure is critical for reducing infection and improving aesthetic and functional outcomes for patients with acute burn wounds and nonthermal full-thickness skin defects. Treatment of partial-thickness burns or full-thickness injuries with autologous skin cell suspension (ASCS) achieves robust wound closure while limiting the amount of donor skin compared with standard autografting. A Next Generation Autologous Cell Harvesting Device (NG-ACHD) was developed to standardize the preparation process for ASCS to ensure biological attributes are obtained known to correlate with well-established safety and performance data. This study compared ASCS prepared using the NG-ACHD and ACHD following the manufacturer's guidance, evaluating cellular yields, viability, apoptotic activity, aggregates, phenotypes and functional capacity. Non-inferiority was established for all biological attributes tested and comparable healing trajectories were demonstrated using an in vitro skin regeneration model. In addition to standardization, the NG-ACHD also provides workflow efficiencies with the potential to decrease training requirements and increase the ease of incorporation and utilization of ASCS in clinical practice.

Limited debridement combined with ReCell® Techniques for deep second-degree burns

BACKGROUND

The purpose of this article is to introduce a method that combines limited debridement and ReCell® autologous cell regeneration techniques for the treatment of deep second-degree burn wounds.

METHOD

A total of 20 patients suffered with deep second-degree burns less than 10% of total body surface area (TBSA) who were admitted to our department, from June 2019 to June 2021, participated in this study. These patients first underwent limited debridement with an electric/pneumatic dermatome, followed by the ReCell® technique for secondary wounds. Routine treatment was applied to prevent scarring after the wound healed. Clinical outcomes were scored using the Vancouver Scar Scale (VSS).

RESULTS

All wounds of the patients healed completely. One patient developed an infection in the skin graft area and finally recovered by routine dressing changes. The average healing time was 12 days (range: 10-15 days). The new skin in the treated area was soft and matched the colour of the surrounding normal skin and the VSS score ranged from 3~5 for each patient. Of the 20 patients, 19 were very satisfied and 1 was satisfied.

CONCLUSIONS

This article reports a useful treatment method that combines electric dermatome-dependent limited debridement and the ReCell® technique for the treatment of deep second-degree burn wounds. It is a feasible and effective strategy that is easy to implement and minimally invasive, and it is associated with a short healing time, mild scar formation and little damage to the donor skin area.

A novel method for the establishment of autologous skin cell suspensions: characterisation of cellular sub-populations, epidermal stem cell content and wound response-enhancing biological properties

Introduction: Autologous cell suspension (ACS)-based therapy represents a highly promising approach for burns and chronic wounds. However, existing technologies have not achieved the desired clinical success due to several limitations. To overcome practical and cost-associated obstacles of existing ACS methods, we have established a novel methodology for rapid, enzymatic disaggregation of human skin cells and their isolation using a procedure that requires no specialist laboratory instrumentation and is performed at room temperature. Methods: Cells were isolated using enzymatic disaggregation of split-thickness human skin followed by several filtration steps for isolation of cell populations, and cell viability was determined. Individual population recovery was confirmed in appropriate culture medium types, and the presence of epidermal stem cells (EpSCs) within keratinocyte sub-populations was defined by flow cytometry via detection of CD49 and CD71. Positive mediators of wound healing secreted by ACS-derived cultures established on a collagen-based wound-bed mimic were detected by proteome arrays and quantified by ELISA, and the role of such mediators was determined by cell proliferation assays. The effect of ACS-derived conditioned-medium on myofibroblasts was investigated using an in-vitro model of myofibroblast differentiation via detection of α-SMA using immunoblotting and immunofluorescence microscopy. Results: Our methodology permitted efficient recovery of keratinocytes, fibroblasts and melanocytes, which remained viable upon long-term culture. ACS-derivatives comprised sub-populations with the CD49-high/CD71-low expression profile known to demarcate EpSCs. Via secretion of mitogenic factors and wound healing-enhancing mediators, the ACS secretome accelerated keratinocyte proliferation and markedly curtailed cytodifferentiation of myofibroblasts, the latter being key mediators of fibrosis and scarring. Discussion: The systematic characterisation of the cell types within our ACS isolates provided evidence for their superior cell viability and the presence of EpSCs that are critical drivers of wound healing. We defined the biological properties of ACS-derived keratinocytes, which include ability to secrete positive mediators of wound healing as well as suppression of myofibroblast cytodifferentiation. Thus, our study provides several lines of evidence that the established ACS isolates comprise highly-viable cell populations which can physically support wound healing and possess biological properties that have the potential to enhance not only the speed but also the quality of wound healing.

Autologous Skin Cell Suspension for Full-Thickness Skin Defect Reconstruction: Current Evidence and Health Economic Expectations

Despite differing etiologies, acute thermal burn injuries and full-thickness (FT) skin defects are associated with similar therapeutic challenges. When not amenable to primary or secondary closure, the conventional standard of care (SoC) treatment for these wound types is split-thickness skin grafting (STSG). This invasive procedure requires adequate availability of donor skin and is associated with donor site morbidity, high healthcare resource use (HCRU), and costs related to prolonged hospitalization. As such, treatment options that can facilitate effective healing and donor skin sparing have been highly anticipated. The RECELL® Autologous Cell Harvesting Device facilitates preparation of an autologous skin cell suspension (ASCS) for the treatment of acute thermal burns and FT skin defects. In initial clinical trials, the approach showed superior donor skin-sparing benefits and comparable wound healing to SoC STSG among patients with acute thermal burn injuries. These findings led to approval of RECELL for this indication by the US Food and Drug Administration (FDA) in 2018. Subsequent clinical evaluation in non-thermal FT skin wounds showed that RECELL, when used in combination with widely meshed STSG, provides donor skin-sparing advantages and comparable healing outcomes compared with SoC STSG. As a result, the device received FDA approval in June of 2023 for treatment of FT skin defects caused by traumatic avulsion or surgical excision or resection. Given that health economic advantages have been demonstrated for RECELL ± STSG versus STSG alone when used for burn therapy, it is prudent to examine similarities in the burn and FT skin defect treatment pathways to forecast the potential health economic advantages for RECELL when used in FT skin defects. This article discusses the parallels between the two indications, the clinical outcomes reported for RECELL, and the HCRU and cost benefits that may be anticipated with use of the device for non-thermal FT skin defects.

Effectiveness of a Regenerative Epithelial Suspension (RES), on the pigmentation of split-thickness skin graft donor sites in children: the dRESsing pilot randomised controlled trial protocol

BACKGROUND

Paediatric donor site wounds are often complicated by dyspigmentation following a split-thickness skin graft. These easily identifiable scars can potentially never return to normal pigmentation. A Regenerative Epidermal Suspension (RES) has been shown to improve pigmentation in patients with vitiligo, and in adult patients following a burn injury. Very little is known regarding the efficacy of RES for the management of donor site scars in children.

METHODS AND ANALYSIS

A pilot randomised controlled trial of 40 children allocated to two groups (RES or no RES) standard dressing applied to donor site wounds will be conducted. All children aged 16 years or younger requiring a split thickness skin graft will be screened for eligibility. The primary outcome is donor site scar pigmentation 12 months after skin grafting. Secondary outcomes include re-epithelialisation time, pain, itch, dressing application ease, treatment satisfaction, scar thickness and health-related quality of life. Commencing 7 days after the skin graft, the dressing will be changed every 3-5 days until the donor site is ≥ 95% re-epithelialised. Data will be collected at each dressing change and 3, 6 and 12 months post skin graft.

ETHICS AND DISSEMINATION

Ethics approval was confirmed on 11 February 2019 by the study site Human Research Ethics Committee (HREC) (HREC/18/QCHQ/45807). Study findings will be published in peer-reviewed journals and presented at national and international conferences. This study was prospectively registered on the Australian New Zealand Clinical Trials Registry (available at https://anzctr.org.au/ACTRN12620000227998.aspx).

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry [Available at https://anzctr.org.au/ACTRN12620000227998.aspx].

Maximizing wound coverage in full-thickness skin defects: A randomized-controlled trial of autologous skin cell suspension and widely meshed autograft versus standard autografting

BACKGROUND

Traumatic insults, infection, and surgical procedures can leave skin defects that are not amenable to primary closure. Split-thickness skin grafting (STSG) is frequently used to achieve closure of these wounds. Although effective, STSG can be associated with donor site morbidity, compounding the burden of illness in patients undergoing soft tissue reconstruction procedures. With an expansion ratio of 1:80, autologous skin cell suspension (ASCS) has been demonstrated to significantly decrease donor skin requirements compared with traditional STSG in burn injuries. We hypothesized that the clinical performance of ASCS would be similar for soft tissue reconstruction of nonburn wounds.

METHODS

A multicenter, within-patient, evaluator-blinded, randomized-controlled trial was conducted of 65 patients with acute, nonthermal, full-thickness skin defects requiring autografting. For each patient, two treatment areas were randomly assigned to concurrently receive a predefined standard-of-care meshed STSG (control) or ASCS + more widely meshed STSG (ASCS+STSG). Coprimary endpoints were noninferiority of ASCS+STSG for complete treatment area closure by Week 8, and superiority for relative reduction in donor skin area.

RESULTS

At 8 weeks, complete closure was observed for 58% of control areas compared with 65% of ASCS+STSG areas (p = 0.005), establishing noninferiority of ASCS+STSG. On average, 27.4% less donor skin was required with ASCS+ STSG, establishing superiority over control (p < 0.001). Clinical healing (≥95% reepithelialization) was achieved in 87% and 85% of Control and ASCS+STSG areas, respectively, at 8 weeks. The treatment approaches had similar long-term scarring outcomes and safety profiles, with no unanticipated events and no serious ASCS device-related events.

CONCLUSION

ASCS+STSG represents a clinically effective and safe solution to reduce the amount of skin required to achieve definitive closure of full-thickness defects without compromising healing, scarring, or safety outcomes. This can lead to reduced donor site morbidity and potentially decreased cost associated with patient care.Clincaltrials.gov identifier: NCT04091672.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level I.

Telomerase mRNA Enhances Human Skin Engraftment for Wound Healing

Deep skin wounds represent a serious condition and frequently require split-thickness skin grafts (STSG) to heal. The application of autologous human-skin-cell-suspension (hSCS) requires less donor skin than STSG without compromising the healing capacity. Impaired function and replicative ability of senescent cutaneous cells in the aging skin affects healing with autologous hSCS. Major determinants of senescence are telomere erosion and DNA damage. Human telomerase reverse transcriptase (hTERT) adds telomeric repeats to the DNA and can protect against DNA damage. Herein, hTERT mRNA lipid nanoparticles (LNP) are proposed and evaluated for enhancing cellular engraftment and proliferation of hSCS. Transfection with optimized hTERT mRNA LNP system enables delivery and expression of mRNA in vitro in keratinocytes, fibroblasts, and in hSCS prepared from donors' skin. Telomerase activity in hSCS is significantly increased. hTERT mRNA LNP enhance the generation of a partial-thickness human skin equivalent in the mouse model, increasing hSCS engraftment (Lamin) and proliferation (Ki67), while reducing cellular senescence (p21) and DNA damage (53BP1).

Preclinical study of diabetic foot ulcers: From pathogenesis to vivo/vitro models and clinical therapeutic transformation

Diabetic foot ulcer (DFU), a common intractable chronic complication of diabetes mellitus (DM), has a prevalence of up to 25%, with more than 17% of the affected patients at risk of amputation or even death. Vascular risk factors, including vascular stenosis or occlusion, dyslipidemia, impaired neurosensory and motor function, and skin infection caused by trauma, all increase the risk of DFU in patients with diabetes. Therefore, diabetic foot is not a single pathogenesis. Preclinical studies have contributed greatly to the pathogenesis determination and efficacy evaluation of DFU. Many therapeutic tools are currently being investigated using DFU animal models for effective clinical translation. However, preclinical animal models that completely mimic the pathogenesis of DFU remain unexplored. Therefore, in this review, the preparation methods and evaluation criteria of DFU animal models with three major pathological mechanisms: neuropathy, angiopathy and DFU infection were discussed in detail. And the advantages and disadvantages of various DFU animal models for clinical sign simulation. Furthermore, the current status of vitro models of DFU and some preclinical studies have been transformed into clinical treatment programs, such as medical dressings, growth factor therapy, 3D bioprinting and pre-vascularization, Traditional Chinese Medicine treatment. However, because of the complexity of the pathological mechanism of DFU, the clinical transformation of DFU model still faces many challenges. We need to further optimize the existing preclinical studies of DFU to provide an effective animal platform for the future study of pathophysiology and clinical treatment of DFU.

Quality management overview for the production of a tissue-engineered human skin substitute in Malaysia

Treatments for skin injuries have recently advanced tremendously. Such treatments include allogeneic and xenogeneic transplants and skin substitutes such as tissue-engineered skin, cultured cells, and stem cells. The aim of this paper is to discuss the general overview of the quality assurance and quality control implemented in the manufacturing of cell and tissue product, with emphasis on our experience in the manufacturing of MyDerm®, an autologous bilayered human skin substitute. Manufacturing MyDerm® requires multiple high-risk open manipulation steps, such as tissue processing, cell culture expansion, and skin construct formation. To ensure the safety and efficacy of this product, the good manufacturing practice (GMP) facility should establish a well-designed quality assurance and quality control (QA/QC) programme. Standard operating procedures (SOP) should be implemented to ensure that the manufacturing process is consistent and performed in a controlled manner. All starting materials, including tissue samples, culture media, reagents, and consumables must be verified and tested to confirm their safety, potency, and sterility. The final products should also undergo a QC testing series to guarantee product safety, efficacy, and overall quality. The aseptic techniques of cleanroom operators and the environmental conditions of the facility are also important, as they directly influence the manufacturing of good-quality products. Hence, personnel training and environmental monitoring are necessary to maintain GMP compliance. Furthermore, risk management implementation is another important aspect of QA/QC, as it is used to identify and determine the risk level and to perform risk assessments when necessary. Moreover, procedures for non-conformance reporting should be established to identify, investigate, and correct deviations that occur during manufacturing. This paper provides insight and an overview of the QA/QC aspect during MyDerm® manufacturing in a GMP-compliant facility in the Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia.

Autologous Skin Cell Suspension in Toxic Epidermal Necrolysis: A Case Series

Toxic epidermal necrolysis (TEN) is a dermatological process which has lacked both clear pathophysiological definition and efficacious medical treatment. This leads to metabolic dysfunction due to the inability to regulate fluid and electrolytes after the loss of skin. It is a deadly and costly disease which is associated with long lengths of stay and high-mortality rates. The depth of TEN mimics that of a partial-thickness burn. There has been documentation of successful usage of autologous skin cell suspension (ASCS) in TEN. This study expands upon our previous experience using ASCS in TEN to a series of three. Dermatology is consulted for biopsy along with the burn surgery team for wound care, where a Score for TEN is performed for risk stratification. Aggressive operative debridement is performed in the operative suite and a healthy, uninvolved donor site is harvested and processed per standard protocol. Dressings are taken down at postoperative day 4 for evaluation. The average length of stay when compared to historical data in literature is a reduction by 48%. ICU days were reduced by 64%. Cost was reduced by 54%. There was no mortality in our population of three. ASCS is both therapeutically and cost effective at treating TEN. The question of type of dressing and decision to operate is mitigated by this intervention. As an efficacious intervention, it reduces hospital stay, reduces wound cares, speeds healing, and provides a cosmetically acceptable outcome.

Efficacy of stromal vascular fraction and enzyme-free mechanical isolation therapy in experimental full thickness burn wounds

BACKGROUND

Autologous cell suspensions obtained by a stromal vascular fraction (SVF) and enzyme-free mechanical isolation (EMI) are an alternative in the treatment of burn wounds. In this study, we aimed to investigate the effect of autologous cell suspensions obtained by SVF and EMI on full-thickness skin burn wounds.

METHODS

A total of 45 male Sprague-Dawley rats were divided into three groups, SVF group, EMI group, and SVF + EMI group. The groups were also classified as the first, second, and third week of the burn to reveal the effect of the treatment on the burn in the early, middle, and late stages. For treatment, 0.2 ml SVF or 0.2 ml EMI was injected subcutaneously into the burn lesions of the subjects. Histopathological examination was performed on the burn wounds taken at the end of the experiment, and Ki67, CD44, CD73, CD90, and CK17 expressions were evaluated.

RESULTS

Histological examination revealed that there was no improvement in the control samples, but the skin was multicellular, vascularization was present. Histologic scores in all groups was significantly better than control, and SVF + EMI was the best group in terms of recovery (p < 0.05). Ki67, CK17, CD44, CD73, and CD90 expressions were significantly higher in the treatment groups compared to the control (p < 0.05).

CONCLUSION

We found in our study that both applications significantly increased the healing of the burn wound. Moreover, SVF + EMI application provided more improvement than SVF or EMI alone.

Emerging Therapies for Full-Thickness Skin Regeneration

The classical treatment of extensive full-thickness skin loss due to trauma or burns has been the split-thickness skin graft. While split-thickness skin grafts close the wound, they leave patients with visible scars, dry skin, pruritis, pain, pigmentation alterations, and changes in sensation. The optimal replacement for full-thickness skin loss is replacement with intact full-thickness skin. New technologies combined with advances in the understanding of the mechanisms behind wound healing have led to the development of techniques and products that may eventually recapitulate the functions, appearance, and physical properties of normal skin. Autologous homologous skin constructs, minimal functional skin units, and composite bioengineered skin with dermal substitutes all represent potential avenues for full-thickness composite skin development and application in extensive wounds. This article summarizes the progress, state, and future of full-thickness skin regeneration in burn and massive wound patients.

Composition and Performance of Autologous Engineered Skin Substitutes for Repair or Regeneration of Excised, Full-Thickness Burns

Prompt and permanent wound closure after burn injuries remains a requirement for patient recovery. Historically, split-thickness skin autograft (STAG) has served as the prevailing standard of care for closure of extensive, deep burns. Because STAG availability may be insufficient in life-threatening burns, alternatives have been evaluated for safety and efficacy of wound closure. Since the 1970s, alternatives consisting of cultured epidermal keratinocytes, and/or acellular dermal substitutes were studied and translated into services and devices that facilitated wound closure, survival, and recovery after major burns. Cultured epithelial autografts (CEA) promoted epidermal closure of wounds but were not stable during long-term recovery. An acellular dermal substitute consisting of collagen and glycosaminoglycans (C-GAG) provided more uniform dermal repair, and reduced needs for epidermal harvesting but was subject to loss from microbial contamination. More recently, an autologous engineered skin substitute (ESS) has been reported and includes a C-GAG polymer populated with fibroblasts and keratinocytes which form basement membrane. ESS can be applied clinically over a vascularized dermal substitute and generates stable wound closure that is smooth, soft, and strong. Despite these advances, no current alternatives for permanent wound closure restore the anatomy and physiology of uninjured skin. Current alternatives act by mechanisms of wound healing, not by developmental biology by which skin forms in utero with pigment, hair, sweat and sebaceous glands, microvasculature, and nerve. Until full-thickness burns are restored with all of the normal structures and functions of uninjured skin, regenerative medicine of skin will remain an ambitious aspiration for future researchers and engineers to achieve.

The Role of Cell-Based Therapies in Acute Burn Wound Skin Repair: A Review

Tissue engineering solutions for skin have been developed over the last few decades with a focus initially on a two-layered structure with epithelial and dermal repair. An essential element of skin restoration is a source of cells capable of differentiating into the appropriate phenotype. The need to repair areas of skin when traditional techniques were not adequate addressed led to cell based therapies being developed initially as a laboratory-based tissue expansion opportunity, both as sheets of cultured epithelial autograft and in composite laboratory-based skin substitutes. The time to availability of the cell-based therapies has been solved in a number of ways, from using allograft cell-based solutions to the use of point of care skin cell harvesting for immediate clinical use. More recently pluripotential cells have been explored providing a readily available source of cells and cells which can express the broad range of phenotypes seen in the mature skin construct. The lessons learnt from the use of cell based techniques has driven the exploration of the use of 3D printing technology, with controlled accurate placement of the cells within a specific printed construct to optimise the phenotypic expression and tissue generation.

Skin Tissue Engineering Advances in Burns: A Brief Introduction to the Past, the Present, and the Future Potential

Burn injuries are a severe form of skin damage with a significant risk of scarring and systemic sequelae. Approximately 11 million individuals worldwide suffer burn injuries annually, with 180,000 people dying due to their injuries. Wound healing is considered the main determinant for the survival of severe burns and remains a challenge. The surgical treatment of burn wounds entails debridement of necrotic tissue, and the wound is covered with autologous skin substitutes taken from healthy donor areas. Autologous skin transplantation is still considered to be the gold standard for wound repair. However, autologous skin grafts are not always possible, especially in cases with extensive burns and limited donor sites. Allografts from human cadaver skin and xenografts from pig skin may be used in these situations to cover the wounds temporarily. Alternatively, dermal analogs are used until permanent coverage with autologous skin grafts or artificial skins can be achieved, requiring staged procedures to prolong the healing times with the associated risks of local and systemic infection. Over the last few decades, the wound healing process through tissue-engineered skin substitutes has significantly enhanced as the advances in intensive care ensuring early survival have led to the need to repair large skin defects. The focus has shifted from survival to the quality of survival, necessitating accelerated wound repair. This special volume of JBCR is dedicated to the discoveries, developments, and applications leading the reader into the past, present, and future perspectives of skin tissue engineering in burn injuries.

Advances in Skin Tissue Engineering and Regenerative Medicine

There are an estimated 500,000 patients treated with full-thickness wounds in the United States every year. Fire-related burn injuries are among the most common and devastating types of wounds that require advanced clinical treatment. Autologous split-thickness skin grafting is the clinical gold standard for the treatment of large burn wounds. However, skin grafting has several limitations, particularly in large burn wounds, where there may be a limited area of non-wounded skin to use for grafting. Non-cellular dermal substitutes have been developed but have their own challenges; they are expensive to produce, may require immunosuppression depending on design and allogenic cell inclusion. There is a need for more advanced treatments for devastating burns and wounds. This manuscript provides a brief overview of some recent advances in wound care, including the use of advanced biomaterials, cell-based therapies for wound healing, biological skin substitutes, biological scaffolds, spray on skin and skin bioprinting. Finally, we provide insight into the future of wound care and technological areas that need to be addressed to support the development and incorporation of these technologies.

Air-Pressure-Supported Application of Cultured Human Keratinocytes in a Fibrin Sealant Suspension as a Potential Clinical Tool for Large-Scale Wounds

The treatment of large-scale skin wounds remains a therapeutic challenge. In most cases there is not enough autologous material available for full coverage. Cultured epithelial autografts are efficient in restoring the lost epidermal cover; however, they have some disadvantages, such as difficult application and protracted cell cultivation periods. Transplanting a sprayed keratinocyte suspension in fibrin sealant as biological carrier is an option to overcome those disadvantages. Here, we studied different seeding techniques regarding their applicability and advantages on cell survival, attachment, and outgrowth in vitro and thereby improve the cell transfer to the wound bed. Human primary keratinocytes were suspended in a fibrin sealant. WST-8 assay was used to evaluate the vitality for 7 days. Furthermore, the cells were labeled with CellTracker™ CM-Di-I and stained with a life/dead staining. Cell morphology, shape, and distribution were microscopically analyzed. There was a significant increase in vitality while cultivating the cells in fibrin. Sprayed cells were considerably more homogenously distributed. Sprayed cells reached the confluent state earlier than dripped cells. There was no difference in the vitality and morphology in both groups over the observation period. These findings indicate that the sprayed keratinocytes are superior to the application of the cells as droplets. The sprayed application may offer a promising therapeutic option in the treatment of large chronic wounds.

The Role of Skin Substitutes in Acute Burn and Reconstructive Burn Surgery: An Updated Comprehensive Review

Burns disrupt the protective skin barrier with consequent loss of cutaneous temperature regulation, infection prevention, evaporative losses, and other vital functions. Chronically, burns lead to scarring, contractures, pain, and impaired psychosocial well-being. Several skin substitutes are available and replace the skin and partially restore functional outcomes and improve cosmesis. We performed a literature review to update readers on biologic and synthetic skin substitutes to date applied in acute and reconstructive burn surgery. Improvement has been rapid in the development of skin substitutes in the last decade; however, no available skin substitute fulfills criteria as a perfect replacement for damaged skin.

Advances in spray products for skin regeneration

To date, skin wounds are still an issue for healthcare professionals. Although numerous approaches have been developed over the years for skin regeneration, recent advances in regenerative medicine offer very promising strategies for the fabrication of artificial skin substitutes, including 3D bioprinting, electrospinning or spraying, among others. In particular, skin sprays are an innovative technique still under clinical evaluation that show great potential for the delivery of cells and hydrogels to treat acute and chronic wounds. Skin sprays present significant advantages compared to conventional treatments for wound healing, such as the facility of application, the possibility to treat large wound areas, or the homogeneous distribution of the sprayed material. In this article, we review the latest advances in this technology, giving a detailed description of investigational and currently commercially available acellular and cellular skin spray products, used for a variety of diseases and applying different experimental materials. Moreover, as skin sprays products are subjected to different classifications, we also explain the regulatory pathways for their commercialization and include the main clinical trials for different skin diseases and their treatment conditions. Finally, we argue and suggest possible future trends for the biotechnology of skin sprays for a better use in clinical dermatology.

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Skin sprays represent a promising technique for wound healing applications.

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Skin sprays can deliver cells and hydrogels with great facility over large wounds.

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Many skin spray products have been studied, only a few have been commercialized.

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Numerous clinical trials study spray products for skin diseases like psoriasis.

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Improved spraying devices should be developed for different materials and cells.

Reversibly immortalized keratinocytes (iKera) facilitate re-epithelization and skin wound healing: Potential applications in cell-based skin tissue engineering

Skin injury is repaired through a multi-phase wound healing process of tissue granulation and re-epithelialization. Any failure in the healing process may lead to chronic non-healing wounds or abnormal scar formation. Although significant progress has been made in developing novel scaffolds and/or cell-based therapeutic strategies to promote wound healing, effective management of large chronic skin wounds remains a clinical challenge. Keratinocytes are critical to re-epithelialization and wound healing. Here, we investigated whether exogenous keratinocytes, in combination with a citrate-based scaffold, enhanced skin wound healing. We first established reversibly immortalized mouse keratinocytes (iKera), and confirmed that the iKera cells expressed keratinocyte markers, and were responsive to UVB treatment, and were non-tumorigenic. In a proof-of-principle experiment, we demonstrated that iKera cells embedded in citrate-based scaffold PPCN provided more effective re-epithelialization and cutaneous wound healing than that of either PPCN or iKera cells alone, in a mouse skin wound model. Thus, these results demonstrate that iKera cells may serve as a valuable skin epithelial source when, combining with appropriate biocompatible scaffolds, to investigate cutaneous wound healing and skin regeneration.

Autologous skin cell suspension application for toxic epidermal necrolysis: a case report

Toxic epidermal necrolysis is a drug-mediated disease process which mimics a partial thickness thermal injury. It has long been treated with frequent wound dressing changes and supportive care. There has been minimal efficacious system therapy. The pathophysiology is poorly understood but causes necrosis of keratinocytes at the dermal-epidermal junction leading to sloughing of the epidermis. The disease is rare with high mortality rates associated with long hospital stays. This case report describes the application of autologous skin cell suspension to a patient with toxic epidermal necrolysis after antihypertensive and hyperglycemic therapy. This was associated with minimal wound care and efficacious arrest of patient disease process and timely closure of wound.

The Current Challenges on Spray-Based Cell Delivery to the Skin Wounds

Cell delivery through spray instruments is a promising and effective method in tissue engineering and regenerative medicine. It is used for treating different acute and chronic wounds, including burns with different etiologies, chronic diabetic or venous wounds, postcancer surgery, and hypopigmentation disorders. Cell spray can decrease the needed donor site area compared with conventional autologous skin grafting. Keratinocytes, fibroblasts, melanocytes, and mesenchymal stem cells are promising cell sources for cell spray procedures. Different spray instruments are designed and utilized to deliver the cells to the intended skin area. In an efficient spray instrument, cell viability and wound coverage are two determining parameters influenced by various physical and biological factors such as air pressure, spraying distance, viscosity of suspension, stiffness of the wound surface, and velocity of impact. Besides, to improve cell delivery by spray instruments, some matrices and growth factors can be added to cell suspensions. This review focuses on the different types of cells and spray instruments used in cell delivery procedures. It also discusses physical and biological parameters associated with cell viability and wound coverage in spray instruments. Moreover, the recent advances in codelivery of cells with biological glues and growth factors, as well as clinical translation of cell spraying, have been reviewed. Impact statement Skin wounds are a group of prevalent injuries that can lead to life-threatening complexities. As a focus of interest, stem cell therapy and spray-based cell delivery have effectively decreased associated morbidity and mortality. This review summarizes a broad scope of recent evidence related to spray-based cell therapy, instruments, and approaches adopted to make the process more efficient in treating skin wounds. An overview including utilized cell types, clinical cases, and current challenges is also provided.

A systematic review and meta-analysis of randomized trials evaluating the efficacy of autologous skin cell suspensions for re-epithelialization of acute partial thickness burn injuries and split-thickness skin graft donor sites

BACKGROUND

This systematic review evaluated the efficacy of autologous skin cell suspensions (ASCS) on the re-epithelialization of partial thickness burn injuries and skin graft donor site wounds.

METHODS

Four databases (EMBASE, Google Scholar, MEDLINE, Web of Science), grey literature and select journal hand-searching identified studies from 1975 - 2020. Randomized trials evaluating partial thickness burn management with non-cultured ASCS compared to any other intervention were included. Time to re-epithelialization (TTRE) was the primary outcome. Three independent researchers completed screening, data extraction and certainty of evidence assessment using Cochrane Risk of Bias Tool and Grading of Recommendations Assessment, Development and Evaluation.

RESULTS

Five trials (n = 347) reported on adults (2 trials) and children (1 trial) with burn wounds, and adults with donor site wounds (2 trials). The effect of ASCS compared to control on TTRE in adult burn wounds was not estimable. TTRE was shorter in pediatric burn wounds (SMD -1.75 [95% CI: -3.45 to -0.05]) and adult donor site wounds (SMD-5.71 [95% CI: -10.61 to-0.81]) treated with ASCS. The certainty of evidence was very low.

CONCLUSION

Compared to standard care, ACSC may reduce pediatric partial thickness burn wound and adult split-thickness skin graft donor site TTRE.

REGISTRATION

PROSPERO CRD42019133171.

Initial Experience Combining Negative Pressure Wound Therapy With Autologous Skin Cell Suspension and Meshed Autografts

The success of autologous split-thickness skin grafts (STSGs) in the treatment of full-thickness burns is often dependent on the dressing used to secure it. Tie-over bolsters have been used traditionally; however, they can be uncomfortable for patients and preclude grafting large areas in one definitive operation. Negative pressure wound therapy (NPWT) is used as an alternative to bolster dressings and may afford additional wound healing benefits. In our center, NPWT has become the dressing of choice for securing STSGs. While the RECELL® system is being used in conjunction with STSGs, it is currently unknown whether autologous skin cell suspensions (ASCS) can be used with NPWT. This report is a retrospective chart review of nine patients treated in this manner. All wounds were almost completely re-epithelialized within 14 days, and their healing was as expected. Wound healing trajectories are shown. There were no significant complications in these patients. This dressing technique can be considered as an option when using ASCS and widely meshed STSG.

Myofibroblasts: Function, Formation, and Scope of Molecular Therapies for Skin Fibrosis

Myofibroblasts are contractile, α-smooth muscle actin-positive cells with multiple roles in pathophysiological processes. Myofibroblasts mediate wound contractions, but their persistent presence in tissues is central to driving fibrosis, making them attractive cell targets for the development of therapeutic treatments. However, due to shared cellular markers with several other phenotypes, the specific targeting of myofibroblasts has long presented a scientific and clinical challenge. In recent years, myofibroblasts have drawn much attention among scientific research communities from multiple disciplines and specialisations. As further research uncovers the characterisations of myofibroblast formation, function, and regulation, the realisation of novel interventional routes for myofibroblasts within pathologies has emerged. The research community is approaching the means to finally target these cells, to prevent fibrosis, accelerate scarless wound healing, and attenuate associated disease-processes in clinical settings. This comprehensive review article describes the myofibroblast cell phenotype, their origins, and their diverse physiological and pathological functionality. Special attention has been given to mechanisms and molecular pathways governing myofibroblast differentiation, and updates in molecular interventions.

A Pilot Study of Negative Pressure Therapy with Autologous Skin Cell Suspensions in a Porcine Model

BACKGROUND

Negative pressure wound therapy (NPWT) is an option for securing meshed split thickness skin grafts (mSTSGs) after burn excision to optimize skin graft adherence. Recently, the use of autologous skin cell suspension (ASCS) has been approved for use in the treatment of burn injuries in conjunction with mSTSGs.To date, limited data exists regarding the impact of NPWT on healing outcomes when the cellular suspension is utilized. It was hypothesized that NPWT would not negatively impact wound healing of ASCS+mSTSG.

MATERIALS AND METHODS

A burn, excision, mSTSG, ASCS ± NPWT model was used. Two Duroc pigs were utilized in this experiment, each with 2 sets of paired burns. Four wounds received mSTSG+ASCS+NPWT through post-operative day 3, and 4 wounds received mSTSG+ACSC+ traditional ASCS dressings. Cellular viability was characterized prior to spraying. Percent re-epithelialization, graft-adherence, pigmentation, elasticity, and blood perfusion and blood vessel density were assessed at multiple time points through 2 weeks.

RESULTS

All wounds healed within 14 days with minimal scar pathology and no significant differences in percent re-epithelialization between NPWT, and non-NPWT wounds were observed. Additionally, no differences were detected for pigmentation, perfusion, or blood vessel density. NPWT treated wounds had less graft loss and improved elasticity, with elasticity being statistically different.

CONCLUSIONS

These data suggest the positive attributes of the cellular suspension delivered are retained following the application of negative pressure. Re-epithelialization, revascularization, and repigmentation are not adversely impacted. The use of NPWT may be considered as an option when using ASCS with mSTSGs for the treatment of full-thickness burns.

Skin substitutes with noncultured autologous skin cell suspension heal porcine full-thickness wounds in a one-stage procedure

Clinical application of skin substitute is typically a two-stage procedure with application of skin substitute matrix to the wound followed by engraftment of a split-thickness skin graft (STSG). This two-stage procedure requires multiple interventions, increasing the time until the wound is epithelialised. In this study, the feasibility of a one-stage procedure by combining bioengineered collagen-chondroitin-6-sulfate (DS1) or decellularised fetal bovine skin substitute (DS2) with autologous skin cell suspension (ASCS) in a porcine full-thickness wound healing model was evaluated. Twelve full-thickness excisional wounds on the backs of pigs received one of six different treatments: empty; ASCS; DS1 with or without ASCS; DS2 with or without ASCS. The ASCS was prepared using a point-of-care device and was seeded onto the bottom side of DS1, DS2, and empty wounds at 80 000 cells/cm² . Wound measurements and photographs were taken on days 0, 9, 14, 21, 28, 35, and 42 post-wounding. Histological analysis was performed on samples obtained on days 9, 14, 28, and 42. Wounds in the empty group or with ASCS alone showed increased wound contraction, fibrosis, and myofibroblast density compared with other treatment groups. The addition of ASCS to DS1 or DS2 resulted in a marked increase in re-epithelialisation of wounds at 14 days, from 15 ± 11% to 71 ± 20% (DS1 vs DS1 + ASCS) or 28 ± 14% to 77 ± 26 (DS2 vs DS2 + ASCS) despite different mechanisms of tissue regeneration employed by the DS used. These results suggest that this approach may be a viable one-stage treatment in clinical practice.

A Narrative Review of the History of Skin Grafting in Burn Care

Thermal injuries have been a phenomenon intertwined with the human condition since the dawn of our species. Autologous skin translocation, also known as skin grafting, has played an important role in burn wound management and has a rich history of its own. In fact, some of the oldest known medical texts describe ancient methods of skin translocation. In this article, we examine how skin grafting has evolved from its origins of necessity in the ancient world to the well-calibrated tool utilized in modern medicine. The popularity of skin grafting has ebbed and flowed multiple times throughout history, often suppressed for cultural, religious, pseudo-scientific, or anecdotal reasons. It was not until the 1800s, that skin grafting was widely accepted as a safe and effective treatment for wound management, and shortly thereafter for burn injuries. In the nineteenth and twentieth centuries skin grafting advanced considerably, accelerated by exponential medical progress and the occurrence of man-made disasters and global warfare. The introduction of surgical instruments specifically designed for skin grafting gave surgeons more control over the depth and consistency of harvested tissues, vastly improving outcomes. The invention of powered surgical instruments, such as the electric dermatome, reduced technical barriers for many surgeons, allowing the practice of skin grafting to be extended ubiquitously from a small group of technically gifted reconstructive surgeons to nearly all interested sub-specialists. The subsequent development of biologic and synthetic skin substitutes have been spurred onward by the clinical challenges unique to burn care: recurrent graft failure, microbial wound colonization, and limited donor site availability. These improvements have laid the framework for more advanced forms of tissue engineering including micrografts, cultured skin grafts, aerosolized skin cell application, and stem-cell impregnated dermal matrices. In this article, we will explore the convoluted journey that modern skin grafting has taken and potential future directions the procedure may yet go.

New Pigmentation After Medical Treatment Suggests Increased Efficacy of Dermabrasion and Noncultured Epidermal Cell Suspension Techniques in Stable Vitiligo

BACKGROUND

Stable vitiligo has been treated by dermabrasion and noncultured epidermal cell suspension (NCES) effectively. However, not all patches respond well.

OBJECTIVE

To investigate the efficacy of new pigmentation after medical treatment in the therapy of stable vitiligo.

MATERIALS AND METHODS

Medical records were retrospectively reviewed from October 2016 to March 2019, and 134 patients with stable vitiligo after medical therapy were further treated with NCES. They were divided into 2 groups: 70 patients in Group 1 had new pigmentation, whereas 64 patients in Group 2 did not. Repigmentation and satisfaction of patients and third-party assessors were evaluated at 3 and 6 months postoperatively.

RESULTS

Repigmentation was scored as excellent (≥76%), good (51%-75%), fair (26%-50%), or poor (≤25%). Repigmentation of the 2 groups at 6 months postoperatively was excellent in 82.9% versus 23.4%, good in 10.0% versus 15.6%, fair in 7.1% versus 13.0%, and poor in 0% versus 48.4%, respectively. A positive correlation between satisfaction and repigmentation was found.

CONCLUSION

New pigmentation after medical treatment suggests increased efficacy of NCES in treating stable vitiligo.

A Short History of Skin Grafting in Burns: From the Gold Standard of Autologous Skin Grafting to the Possibilities of Allogeneic Skin Grafting with Immunomodulatory Approaches

Due to groundbreaking and pioneering developments in the last century, significant improvements in the care of burn patients have been achieved. In addition to the still valid therapeutic standard of autologous split-thickness skin grafting, various commercially available skin substitutes are currently available. Significant progress in the field of tissue engineering has led to the development of promising therapeutic approaches. However, scientific advances in the field of allografting and transplant immunology are of great importance. The achievement of various milestones over the past decades has provided thought-provoking impulses in the field of skin allotransplantation. Thus, biologically viable skin allotransplantation is still not a part of the clinical routine. The purpose of this article is to review the achievements in burn surgery with regards to skin allotransplantation in recent years.

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.

Coverage of soft tissue defects in acute surgery for deep burns of the limbs

Burns of the limbs affect 48.6% of burn patients. Injury mechanisms condition their depth and degree of extension. Injury of the hands and/or the joint areas entails considerable risk of retraction. Coverage is consequently doubly challenging, it is a matter not only of compensating for a soft tissue defects, but also of striving to prevent early (infectious) and late (amplitude limitation, pain, loss of function…) complications. Thoroughgoing assessment of the initial injury and associated lesions is conducive to rapid determination of a therapeutic strategy tailored to the relevant functional issues and subsequent rehabilitation. Following a summary of the epidemiological elements and the medical context of management, a review of existing treatments has been drawn up based on the data in the literature and current professional recommendations. Emergency procedures, the different types of excision and the possibilities of autologous covering and skin substitutes are reported. Last but not least, routinely validated indications are synthesized.

Complex approach to skin repair in an extensively burned child: a case study

The limited amount of donor sites and loss of dermis are major challenges in the therapy of extensively burned patients. Here, we present a complex treatment approach of an eight-year-old boy with full-thickness burns on 90% of the total body surface area, using simple and efficient techniques of tissue engineering. To obtain sufficient skin for grafting we repeatedly harvested the same anatomical areas. Acceleration of donor site healing was achieved by treatment with a suspension of noncultured autologous skin cells (NASC) and acellular porcine dermis (Xe-Derma (XD), Czech Republic). Moreover, such wound management allowed up to six reharvestings, compared with one-to-three procedures following routine treatment. Bilayer Integra template (Integra LifeSciences Corp., US) was used as the dermal substitute in over 60% of full-thickness burns. Following successful vascularisation of the neodermis in 3-4 weeks, the templates were covered with meshed split-thickness skin grafts (STSG), or Meek autografts, and facilitated by NASC/XD. We may conclude that such a 'sandwich' technique approach, combining four biological covers (Integra, STSG, NASC and XD), significantly contributed to the successful skin repair of the patient.

A pilot multi-centre prospective randomised controlled trial of RECELL for the treatment of venous leg ulcers

Venous leg ulcers (VLUs) have a significant impact on approximately 3% of the adult population worldwide, with a mean NHS wound care cost of £7600 per VLU over 12 months. The standard care for VLUs is compression therapy, with a significant number of ulcers failing to heal with this treatment, especially with wound size being a risk factor for non-healing. This multicentre, prospective, randomised trial evaluated the safety and effectiveness of autologous skin cell suspension (ASCS) combined with compression therapy compared with standard compression alone (Control) for the treatment of VLUs. Incidence of complete wound closure at 14 weeks, donor site closure, pain, Health-Related Quality of Life (HRQoL), satisfaction, and safety were assessed in 52 patients. At Week 14, VLUs treated with ASCS + compression had a statistically greater decrease in ulcer area compared with the Control (8.94 cm2 versus 1.23 cm2 , P = .0143). This finding was largely driven by ulcers >10 to 80 cm2 in size, as these ulcers had a higher mean percentage of reepithelialization at 14 weeks (ASCS + compression: 69.97% and Control: 11.07%, P = .0480). Additionally, subjects treated with ASCS + compression experienced a decrease in pain and an increase in HRQoL compared with the Control. This study indicates that application of ASCS + compression accelerates healing in large venous ulcers.

New Treatment of Wound Healing With Allogenic Acellular Human Skin Graft: Preclinical Assessment and In Vitro Study

BACKGROUND

Nonhealing wounds can be a major clinical problem. Impaired wound healing is often related to massive tissue injury, concomitant wound healing deficiencies (chronic wounds), burn injury, or congenital conditions. We propose a novel biological dressing as an alternative surgical approach. The dressing is a form of an allogenic human skin graft equivalent with further use of allogeneic stem cells classified as an advanced therapy medicinal product. This new allogenic acellular human skin graft has been specifically developed to address the clinical indications for dressing wound lesions and promoting tissue repair in specific rare genetic diseases.

METHODS

This case report illustrates the use of an acellular human skin allograft seeded with multipotent stem cells in the treatment of tissue injuries (burns), congenital conditions, and chronic wounds. Donor-tissue processing yields an acellular dermal matrix with integral collagen bundling and organization, as well as an intact basement membrane complex.

RESULTS

Preclinical observations show prolonged viability of acellular human skin grafts with multipotent stem cells. This was confirmed with histological and electron-microscopic evaluation of biopsies, which demonstrated host-cell infiltration and neovascularization of the biological dressing. Moreover, the dressings were characterized by low immunogenicity, as confirmed by histology exam and T-cell proliferation assays in vitro.

CONCLUSION

Our data confirmed the safety and efficacy of the evaluated acellular human skin grafts, which may be used in patients with rare diseases, such as epidermolysis bullosa, burn injuries, and chronic wounds.

The Clinical Efficacy of ReCell® Autologous Cell Regeneration Techniques Combined with Dermabrasion Treatment in Acne Scars

OBJECTIVE

To evaluate the efficacy of ReCell® autologous cell regeneration techniques combined with dermabrasion treatment on the therapy of acne scars.

METHODS

We analyzed retrospectively 78 patients with acne scars who presented to the Department of Plastic Surgery at Peking Union Medical College Hospital from May 2015 to May 2017; 30 patients were treated with dermabrasion (Group 1), and the other 48 patients were treated with ReCell® autologous regeneration techniques combined with dermabrasion (Group 2). Efficacy was evaluated through self-evaluation of the patient, third-party evaluation and photographs taken before and after treatment. The wound healing time and postoperative complication rate were also recorded.

RESULTS

The study revealed a significant difference in healing time (P < 0.001) between patients treated with dermabrasion (Group 1) and patients treated with ReCell® autologous regeneration techniques combined with dermabrasion (Group 2). The average healing time of Group 1 was 12.30 ± 1.725 days, while the average healing time of Group 2 was 5.27 ± 1.086 days. In Group 2, patient self-evaluation and third-party evaluation were more satisfactory than those of Group 1 (P < 0.001). Moreover, there were no postoperative complications in Group 2 such as pigmentation and scar hyperplasia.

CONCLUSION

The ReCell® technique is simple, minimally invasive, biocompatible and effective in the treatment of acne scars. It can shorten healing time and reduce the occurrence of postoperative complications, thereby providing a safe and effective treatment approach for patients with facial acne scars.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Initial Experience With Autologous Skin Cell Suspension for Treatment of Deep Partial-Thickness Facial Burns

Facial burns present a challenge in burn care, as hypertrophic scarring and dyspigmentation can interfere with patients’ personal identities, ocular and oral functional outcomes, and have long-term deleterious effects. The purpose of this study is to evaluate our initial experience with non-cultured, autologous skin cell suspension (ASCS) for the treatment of deep partial-thickness (DPT) facial burns. Patients were enrolled at a single burn center during a multicenter, prospective, single-arm, observational study involving the compassionate use of ASCS for the treatment of large total BSA (TBSA) burns. Treatment decisions concerning facial burns were made by the senior author. Facial burns were initially excised and treated with allograft. The timing of ASCS application was influenced by an individual’s clinical status; however, all patients were treated within 30 days of injury. Outcomes included subjective cosmetic parameters and the number of reoperations within 3 months. Five patients (4 males, 1 female) were treated with ASCS for DPT facial burns. Age ranged from 2.1 to 40.7 years (mean 18.2 ± 17.3 years). Average follow-up was 231.2 ± 173.1 days (range 63–424 days). Two patients required reoperation for partial graft loss within 3 months in areas of full-thickness injury. There were no major complications and one superficial hematoma. Healing and cosmetic outcomes were equivalent to, and sometimes substantially better than, outcomes typical of split-thickness autografting. Non-cultured, ASCS was successfully used to treat DPT facial burns containing confluent dermis with remarkable cosmetic outcomes. Treatment of DPT burns with ASCS may be an alternative to current treatments, particularly in patients prone to dyspigmentation, scarring sequelae, and with limited donor sites.

A Comparative Study of the ReCell® Device and Autologous Spit-Thickness Meshed Skin Graft in the Treatment of Acute Burn Injuries

Early excision and autografting are standard care for deeper burns. However, donor sites are a source of significant morbidity. To address this, the ReCell^® Autologous Cell Harvesting Device (ReCell) was designed for use at the point-of-care to prepare a noncultured, autologous skin cell suspension (ASCS) capable of epidermal regeneration using minimal donor skin. A prospective study was conducted to evaluate the clinical performance of ReCell vs meshed split-thickness skin grafts (STSG, Control) for the treatment of deep partial-thickness burns. Effectiveness measures were assessed to 1 year for both ASCS and Control treatment sites and donor sites, including the incidence of healing, scarring, and pain. At 4 weeks, 98% of the ASCS-treated sites were healed compared with 100% of the Controls. Pain and assessments of scarring at the treatment sites were reported to be similar between groups. Significant differences were observed between ReCell and Control donor sites. The mean ReCell donor area was approximately 40 times smaller than that of the Control (P < .0001), and after 1 week, significantly more ReCell donor sites were healed than Controls (P = .04). Over the first 16 weeks, patients reported significantly less pain at the ReCell donor sites compared with Controls (P ≤ .05 at each time point). Long-term patients reported higher satisfaction with ReCell donor site outcomes compared with the Controls. This study provides evidence that the treatment of deep partial-thickness burns with ASCS results in comparable healing, with significantly reduced donor site size and pain and improved appearance relative to STSG.

The Role of Autologous Dermal Micrografts in Regenerative Surgery: A Clinical Experimental Study

The aim of the study was the objective assessment of the effectiveness of a microfragmented dermal extract obtained with Rigenera™ technology in promoting the wound healing process in an in vivo homogeneous experimental human acute surgical wound model. The study included 20 patients with 24 acute postsurgical soft tissue loss and a planned sequential two-stage repair with a dermal substitute and an autologous split-thickness skin graft. Each acute postsurgical soft tissue loss was randomized to be treated either with an Integra® dermal substitute enriched with the autologous dermal micrografts obtained with Rigenera™ technology (group A—Rigenera™ protocol) or with an Integra® dermal substitute only (group B—control). The reepithelialization rate in the wounds was assessed in both groups at 4 weeks through digital photography with the software “ImageJ.” The dermal cell suspension enrichment with the Rigenera™ technology was considered effective if the reepithelialized area was higher than 25% of the total wound surface as this threshold was considered far beyond the expected spontaneous reepithelialization rate. In the Rigenera™ protocol group, the statistical analysis failed to demonstrate any significant difference vs. the controls. The old age of the patients likely influenced the outcome as the stem cell regenerative potential is reduced in the elderly. A further explanation for the unsatisfying results of our trial might be the inadequate amount of dermal stem cells used to enrich the dermal substitutes. In our study, we used a 1 : 200 donor/recipient site ratio to minimize donor site morbidity. The gross dimensional disparity between the donor and recipient sites and the low concentration of dermal mesenchymal stromal stem cells might explain the poor epithelial proliferative boost observed in our study. A potential option in the future might be preconditioning of the dermal stem cell harvest with senolytic active principles that would fully enhance their regenerative potential. This trial is registered with trial protocol number NCT03912675.