Autologous epidermal cell suspension: A promising treatment for chronic wounds

The efficacy and safety of autologous epidermal cell suspensions for re-epithelialization of skin lesions: A systematic review and meta-analysis of randomized trials

BACKGROUND

Successful usage of autologous skin cell suspension (ASCS) has been demonstrated in some clinical trials. However, its efficacy and safety have not been verified. This latest systematic review and meta-analysis aim to examine the effects of autologous epidermal cell suspensions in re-epithelialization of skin lesions.

METHODS

Relevant articles were retrieved from PubMed, Embase, Cochrane Database, Web of Science, International Clinical Trials Registry Platform, China National Knowledge Infrastructureris, VIP Database for Chinese Technical Periodicals and Wanfang database. The primary output measure was the healing time, and the secondary outputs were effective rate, size of donor site for treatment, size of study treatment area, operation time, pain scores, repigmentation, complications, scar scale scores and satisfaction scores. Data were pooled and expressed as relative risk (RR), mean difference (MD) and standardized mean difference (SMD) with a 95% confidence interval (CI).

RESULTS

Thirty-one studies were included in this systematic review and meta-analysis, with 914 patients who received autologous epidermal cell suspensions (treatment group) and 883 patients who received standard care or placebo (control group). The pooled data from all included studies demonstrated that the treatment group has significantly reduced healing time (SMD = -0.86; 95% CI: -1.59-0.14; p = 0.02, I2 = 95%), size of donar site for treatment (MD = -115.41; 95% CI: -128.74-102.09; p<0.001, I2 = 89%), operation time (MD = 25.35; 95% CI: 23.42-27.29; p<0.001, I2 = 100%), pain scores (SMD = -1.88; 95% CI: -2.86-0.90; p = 0.0002, I2 = 89%) and complications (RR = 0.59; 95% CI: 0.36-0.96; p = 0.03, I2 = 66%), as well as significantly increased effective rate (RR = 1.20; 95% CI: 1.01-1.42; p = 0.04, I2 = 77%). There were no significant differences in the size of study treatment area, repigmentation, scar scale scores and satisfaction scores between the two groups.

CONCLUSION

Our meta-analysis showed that autologous epidermal cell suspensions is beneficial for re-epithelialization of skin lesions as they significantly reduce the healing time, size of donar site for treatment, operation time, pain scores and complications, as well as increased effective rate. However, this intervention has minimal impact on size of treatment area, repigmentation, scar scale scores and satisfaction scores.

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.

A Randomized Controlled Study Comparing the Efficacy of Autologous Smashed Follicular Dermal Graft and Epidermal Cell Suspension versus Normal Saline Dressing in the Treatment of Chronic Nonhealing Trophic Ulcers in Patients with Hansen's Disease

Background

Trophic ulcers remain the most common reason for hospitalization in patients with Hansen's disease. With the introduction of new therapeutic regimens, leprosy can now be cured. However, complications of the disease, such as sensory loss, muscle palsy, absorption of extremities, and recurrent ulcers, still lead to substantial morbidity. The management of patients with trophic ulcers and their consequences is difficult, because it is a recurrent and recalcitrant problem.

Aims

To evaluate the efficacy of autologous smashed follicular dermal graft and epidermal cell suspension (ECS) in the treatment of chronic nonhealing trophic ulcers in patients with Hansen's disease and to compare its efficacy with normal saline dressing.

Materials and Methods

A total of 46 chronic nonhealing trophic ulcers were randomized into two groups (23 ulcers in each): Ulcers in Group A were treated with autologous smashed follicular dermal graft and ECS; ulcers in Group B were treated with normal saline dressings. Ulcers were assessed based on the rate of ulcer size reduction at every week till 12 weeks and then once a month till the sixth month.

Results

All 23 (100%) ulcers in Group A had healed within the study period of six months, whereas only 14 (60.9%) ulcers had healed in Group B. Nine (39.1%) ulcers in Group B had not healed even at the end of six months. All 23 (100%) ulcers in Group A had healed within eight weeks, which was statistically significant, P value <0.05.

Conclusion

Trophic ulcers heal faster by autologous smashed follicular dermal graft and ECS, with good results of re-epithelialization of the ulcer bed than by normal saline dressing.

A Systematic Review of Keratinocyte Secretions: A Regenerative Perspective

Cell regenerative therapy is a modern solution for difficult-to-heal wounds. Keratinocytes, the most common cell type in the skin, are difficult to obtain without the creation of another wound. Stem cell differentiation towards keratinocytes is a challenging process, and it is difficult to reproduce in chemically defined media. Nevertheless, a co-culture of keratinocytes with stem cells usually achieves efficient differentiation. This systematic review aims to identify the secretions of normal human keratinocytes reported in the literature and correlate them with the differentiation process. An online search revealed 338 references, of which 100 met the selection criteria. A total of 80 different keratinocyte secretions were reported, which can be grouped mainly into cytokines, growth factors, and antimicrobial peptides. The growth-factor group mostly affects stem cell differentiation into keratinocytes, especially epidermal growth factor and members of the transforming growth factor family. Nevertheless, the reported secretions reflected the nature of the involved studies, as most of them focused on keratinocyte interaction with inflammation. This review highlights the secretory function of keratinocytes, as well as the need for intense investigation to characterize these secretions and evaluate their regenerative capacities.

Emerging treatment strategies in wound care

Wound healing is a complex process in tissue regeneration through which the body responds to the dissipated cells as a result of any kind of severe injury. Diabetic and non-healing wounds are considered an unmet clinical need. Currently, different strategic approaches are widely used in the treatment of acute and chronic wounds which include, but are not limited to, tissue transplantation, cell therapy and wound dressings, and the use of an instrument. A large number of literatures have been published on this topic; however, the most effective clinical treatment remains a challenge. The wound dressing involves the use of a scaffold, usually using biomaterials for the delivery of medication, autologous stem cells, or growth factors from the blood. Antibacterial and anti-inflammatory drugs are also used to stop the infection as well as accelerate wound healing. With an increase in the ageing population leading to diabetes and associated cutaneous wounds, there is a great need to improve the current treatment strategies. This research critically reviews the current advancement in the therapeutic and clinical approaches for wound healing and tissue regeneration. The results of recent clinical trials suggest that the use of modern dressings and skin substitutes is the easiest, most accessible, and most cost-effective way to treat chronic wounds with advances in materials science such as graphene as 3D scaffold and biomolecules hold significant promise. The annual market value for successful wound treatment exceeds over $50 billion US dollars, and this will encourage industries as well as academics to investigate the application of emerging smart materials for modern dressings and skin substitutes for wound therapy.

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.

Efficacy of Autologous Smashed Follicular Dermal Graft and Epidermal Cell Suspension in the Treatment of Chronic Nonhealing Trophic Ulcers in Hansen's Patients

Context:

Plantar ulcers occur in patients with leprosy not because of the disease but because of its neuropathic effects on the skin on the feet. Neuropathy increases the risk of trauma to patients' feet, leading to the development of ulcers. With the introduction of new therapeutic regimens, leprosy can now be cured. However, complications of the disease, such as sensory loss, muscle palsy, absorption of extremities, and recurrent ulcers, still lead to substantial morbidity. This short article reviews the current management of leprosy plantar ulceration in such (nonhealing chronic ulcers) patients.

Aims:

To evaluate the efficacy of autologous smashed follicular dermal graft and epidermal cell suspension in the treatment of chronic nonhealing trophic ulcers in Hansen's patients.

Materials and Methods:

A total of 23 chronic nonhealing trophic ulcers were treated with autologous smashed follicular dermal graft and epidermal cell suspension. Ulcers were assessed based on the rate of ulcer size reduction every week till 12 weeks and then once a month till the sixth month.

Statistical Analysis:

Analysis was done using SPSS 26 software. Independent t-test was used and a P value of <0.05 was considered statistically significant.

Results:

Amongst the Hansen's patients who were released from treatment, all 23 (100%) ulcers had healed within the study period of six months, and all 23 (100%) ulcers had healed within 8 weeks.

Conclusion:

With this modified technique of combining autologous smashed follicular dermal graft with epidermal cell suspension, trophic ulcers heal faster with good results of reepithelialization of the ulcer bed.

Effect of dermal fibroblasts and mesenchymal stem cells seeded on an amniotic membrane scaffold in skin regeneration: A case series

BACKGROUND

Skin wound healing has always been a challenging subject as it involves the coordinated functioning of various cells and molecules. Any disorder in wound healing can cause healing failure and result in chronic wounds. In this study, we hypothesized that co-cultured dermal fibroblasts (DFs) and Wharton's jelly mesenchymal stem cells (WJ-MSCs) seeded on an acellular amniotic membrane scaffold could be used to promote skin regeneration in chronic ulcers.

MATERIALS AND METHODS

In this case series, the chronic wounds of five diabetic patients aged between 30 and 60 years were treated with co-cultured WJ-MSCs and DFs seeded on an acellular amniotic membrane. Treatment was applied and the wound healing process was evaluated every three days for nine days, with the patients being subsequently followed up for one month. The wound healing percentage, time taken for the wound to heal, and wound size were monitored.

RESULTS

The mean wound healing rate (WHR) increased progressively in all lesions. The mean percentage of wound healing after transplantation of the biological scaffold enriched with WJ-MSCs and autologous DFs after treatment was 93.92%, respectively. The healing percentage significantly increased after three days; significant decreases in wound size and healing time were recorded after six and nine days of treatment, respectively (p < 0.002); and total skin regeneration and re-epithelialization were achieved by the ninth day of treatment. There were no side effects or complications.

CONCLUSION

Given the current problems and complications presented by chronic wounds, Novel Clinical approaches involving cell therapy and tissue engineering can be regarded as an attractive therapeutic option for the treatment of chronic and difficult-to-heal wounds.

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.

Chronic Wounds: Innovations in Diagnostics and Therapeutics

BACKGROUND

A major global health issue is the existence of chronic wounds. Appropriate diagnosis and treatment is essential to promote wound healing and prevent further complications. Traditional methods for treatment and diagnosis of chronic wounds have shown to be of limited effectiveness. Therefore, there is a need for the development of diagnostic and therapeutic innovations in chronic wound care.

OBJECTIVE

This mini-review aims to provide insight in the current knowledge of the wound healing process and the deficiencies encountered in chronic wounds, which provides a basis for the development of innovations in chronic wound care. Furthermore, promising diagnostic and therapeutic innovations will be highlighted.

METHODS

Literature was searched for recent articles (=<10 years) describing the current knowledge about the wound healing process and chronic wounds. The most promising diagnostic and therapeutic innovations were gathered from articles published in the past 5 years.

RESULTS/CONCLUSION

Wound healing is a well-organized process consisting of four phases: coagulation, inflammation, proliferation and wound remodelling. Chronic wounds often stagnate in the inflammatory phase and/or experience an impaired proliferative phase. This mini-review has demonstrated that increased knowledge about the processes involved in wound healing has paved the way for the development of new diagnostic tools and treatments for chronic wounds. Increased knowledge about bacterial invasion and infection in has encouraged researchers to develop diagnostic tools to help clinicians detect these phenomena appropriately and in time. Other researchers have shown that they are able to design/extract biochemical compounds that intervene in the disrupted healing processes in chronic wounds.

A Retrospective Study on the Use of Dermis Micrografts in Platelet-Rich Fibrin for the Resurfacing of Massive and Chronic Full-Thickness Burns

The coverage of massive burns still represents a big challenge, even if several strategies are to date available to deal with this situation. In this study, we describe the use of a combination of platelet-rich fibrin and micrograft spray-on skin in order to increase the yield of grafted cells in patients. We treated a total of five patients, of which two were affected by massive burns and three with chronic burn wounds. Briefly, autologous micrografts were obtained by Rigenera technology using a class I medical device called Rigeneracons. The micrografts were then combined with PRF and sprayed on the wound bed by a Spraypen. Before applying PRF/micrograft spray-on skin, the wound bed was covered with an Integra® dermal template, and the wounds were dressed with a layer of antimicrobial dressing applied directly over the silicone layer. When the silicone layer of the dermal template started showing signs of separation, the wound was considered ready for grafting. In all cases, we observed a fast and complete skin graft on average after 7-10 days by PRF/micrograft spray-on skin treatment. In particular, two patients with massive burns reported rapid reepithelialization, and three patients with chronic burn wounds, two of whom had failed skin grafts before the procedure, had complete wound healing within a week. In conclusion, the results showed in this study suggest that the use of PRF/micrograft spray-on skin represents a promising approach in the management of burns or chronic burn wounds.

Healing of Chronic Wounds: An Update of Recent Developments and Future Possibilities

Chronic wounds are the result of disruptions in the body's usual process of healing. They are not only a source of significant pain and discomfort but also, more importantly, an unguarded port of entry for pathogens into the body. While our current understanding of this phenomenon is far from complete, findings in physiological patterns and advancements in wound healing technologies have helped develop wound management and healing solutions to this long-standing medical challenge. This review presents an overview of known wound healing mechanics, abnormalities that lead to chronic wounds, and a summary of established and new wound healing technologies. Various approaches to heal wounds are discussed, from dermal replacements to advanced biomaterial-based treatments, from cell-, synthetic-, and composite-based approaches to preclinical approaches, which make developing such products possible. While tested breakthrough products are described, the authors focused more on recently developed innovations, which are at varying stages of maturity. The review concludes with a note on future perspectives and opinions on where the field and industry are headed and where they should be. Impact Statement Wound healing is an important area of research and clinical practice, and has captured the attention of tissue engineers since the nascent beginnings of the discipline. Tissue-engineered skin was the first FDA-approved product, achieved in 1996. Despite this success, and the passage of time, healing wounds, particularly chronic wounds, remains a vexing challenge. This comprehensive review article will provide readers with a synopsis of current issues, research approaches, animal models, technologies, and products that span the continuum from early development to clinical studies, in the hope of fueling new interests and ideas to overcome this long-standing medical challenge.

Comparative effectiveness of Biobrane®, RECELL® Autologous skin Cell suspension and Silver dressings in partial thickness paediatric burns: BRACS randomised trial protocol

BACKGROUND

Mixed partial thickness burns are the most common depth of burn injury managed at a large Australian paediatric hospital specialty burns unit. Prolonged time until re-epithelialisation is associated with increased burn depth and scar formation. Whilst current wound management approaches have benefits such as anti-microbial cover, these are not without inherent limitations including multiple dressing changes. The Biobrane® RECELL® Autologous skin Cell suspension and Silver dressings (BRACS) trial aims to identify the most effective wound management approach for mixed partial thickness injuries in children.

METHODS

All children presenting with an acute burn injury to the study site will be screened for eligibility. This is a single-centre, three-arm, parallel group, randomised trial. Children younger than 16 years, with burns ≥ 5% total body surface area involving any anatomical location, up to 48 h after the burn injury, and of a superficial partial to mid-dermal depth, will be included. A sample size of 84 participants will be randomised to standard silver dressing or a Regenerative Epithelial Suspension (RES™) with Biobrane® or Biobrane® alone. The first dressing will be applied under general anaesthesia and subsequent dressings will be changed every 3 to 5 days until the wound is ≥ 95% re-epithelialised, with re-epithelialisation time the primary outcome. Secondary outcomes of acute pain, acute itch, scar severity, health-related quality of life, treatment satisfaction, dressing application ease and healthcare resource use will be assessed at each dressing change and 3, 6 and 12 months post-burn injury.

DISCUSSION

The findings of this study can potentially change the wound management approach for superficial partial to mid-dermal burns in children locally and worldwide.

TRIAL REGISTRATION

The Australian New Zealand Clinical Trials Registry (ACTRN12618000245291) approved prospective registration on 15 February 2018. Registration details can be viewed at https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374272&isReview=true.

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

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

Induction of delayed wound healing by irradiation with optional mechanical compression in swine

A chronic wound or non-healing wound is one that fails to heal for at least 30 days after injury. This study was designed to create delayed wound healing induced by irradiation and mechanical compression using silicone block. Two female pigs received a single fraction of 20 Gy with 6-MeV electrons to a 22 × 60 cm field on the dorsal body skin 7 weeks before experimentation. A 30 × 30 mm sized wounds were created with preservation of muscle fascia on the dorsum. In groups of six, wounds were designated to be control (C) or test areas of irradiation only (T0), irradiation with silicone blocks for 1 week (T1), irradiation with silicone blocks for 2 weeks (T2), and irradiation with silicone blocks for 3 weeks (T3). Wound contraction, bacterial culture, and histological analysis were performed at 1-week intervals for 4 weeks. Control wounds displayed complete re-epithelialization at Weeks 4; however, all experimental groups (T0, T1, T2, and T3 groups) showed necrosis and delayed healing at Week 4. The number of bacterial strains in control wounds differed significantly from values recorded for all experimental groups from Weeks 1-3 (p < 0.05). However, in comparing the various test wounds (T0, T1, T2, and T3 groups), the numbers of strains did not differ significantly from Weeks 1-4. In the histological analysis, the control wound showed a peak influx of acute and chronic inflammatory cell and diminished inflammation thereafter. However, all experimental groups showed no peak in inflammatory score and prolonged chronic inflammation. In conclusion, radiation exposure alone, which triggers intense inflammation and extensive recruitment of inflammatory cells, proved sufficient to prevent re-epithelialization of skin at 30 days. Insertion of silicone blocks had limited effects on promoting delayed wound healing. Consequently, we now recommend using irradiation alone to simulate delayed wound healing in an experimental setting.