Wound healing with "spray-on" autologous skin grafting (ReCell) compared with standard care in patients with large diabetes-related foot wounds: an open-label randomised controlled trial

A Degradable Bioelectronic Scaffold for Localized Cell Transfection toward Enhancing Wound Healing in a 3D Space

Large skin wounds, with extensive surface area and deep vertical full-thickness involvement, can pose significant challenges in clinical settings. Traditional routes for repairing skin wounds encompass three hallmarks: 1) scab formation for hemostasis; 2) proliferation and migration of epidermal cells for wound closure; 3) proliferation, migration, and functionalization of fibroblasts and endothelial cells for dermal remodeling. However, this route face remarkable challenges to healing large wounds, usually leading to disordered structures and loss of functions in the regenerated skin, due to limited control on the transition among the three stages. In this work, an implantable bioelectronics is developed that enables the synchronization of the three stages, offering accelerated and high-quality healing of large skin wounds. The system efficiently electro-transfect local cells near the wounds, forcing cellular proliferation, while providing a 3D porous environments for synchronized migration of epidermal and dermal cells. In vivo experiments demonstrated that the system achieved synchronous progression of multiple layers within the wounds, leading to the reconstruction of a complete skin structure similar to healthy skin, which presents a new avenue for the clinical translation of large wound healing.

Benefits of Aerosolized, Point-of-care, Autologous Skin Cell Suspension (ASCS) for the Closure of full Thickness Wounds from Thermal and Non-Thermal 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.

SUMMARY BACKGROUND DATA

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, 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, 33 lower extremities). Mean area grafted was 435 cm2; donor site size was 212 cm2, representing a potential reduction of 50%. Mean surgical time was 71 minutes; total OR time was 124 minutes. Mean length-of-stay was 26.4 days; time from grafting to discharge was 11.2 days. 4/50 patients (8%) required 6 reoperations for bleeding (1), breakdown (4), and amputation (1). 4/50 patients (8%) developed hypertrophic scarring, which responded to silicone sheeting (2) and laser resurfacing (2). Mean follow-up was 92.7 days.

CONCLUSION

When used for 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.

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.

Effectiveness of interventions to enhance healing of chronic foot ulcers in diabetes: A systematic review

BACKGROUND

It is critical that interventions used to enhance the healing of chronic foot ulcers in diabetes are backed by high-quality evidence and cost-effectiveness. In previous years, the systematic review accompanying guidelines published by the International Working Group of the Diabetic Foot performed 4-yearly updates of previous searches, including trials of prospective, cross-sectional and case-control design.

AIMS

Due to a need to re-evaluate older studies against newer standards of reporting and assessment of risk of bias, we performed a whole new search from conception, but limiting studies to randomised control trials only.

MATERIALS AND METHODS

For this systematic review, we searched PubMed, Scopus and Web of Science databases for published studies on randomised control trials of interventions to enhance healing of diabetes-related foot ulcers. We only included trials comparing interventions to standard of care. Two independent reviewers selected articles for inclusion and assessed relevant outcomes as well as methodological quality.

RESULTS

The literature search identified 22,250 articles, of which 262 were selected for full text review across 10 categories of interventions. Overall, the certainty of evidence for a majority of wound healing interventions was low or very low, with moderate evidence existing for two interventions (sucrose-octasulfate and leucocyte, platelet and fibrin patch) and low quality evidence for a further four (hyperbaric oxygen, topical oxygen, placental derived products and negative pressure wound therapy). The majority of interventions had insufficient evidence.

CONCLUSION

Overall, the evidence to support any other intervention to enhance wound healing is lacking and further high-quality randomised control trials are encouraged.

Guidelines on interventions to enhance healing of foot ulcers in people with diabetes (IWGDF 2023 update)

AIMS

Principles of wound management, including debridement, wound bed preparation, and newer technologies involving alternation of wound physiology to facilitate healing, are of utmost importance when attempting to heal a chronic diabetes-related foot ulcer. However, the rising incidence and costs of diabetes-related foot ulcer management necessitate that interventions to enhance wound healing of chronic diabetes-related foot ulcers are supported by high-quality evidence of efficacy and cost effectiveness when used in conjunction with established aspects of gold-standard multidisciplinary care. This is the 2023 International Working Group on the Diabetic Foot (IWGDF) evidence-based guideline on wound healing interventions to promote healing of foot ulcers in persons with diabetes. It serves as an update of the 2019 IWGDF guideline.

MATERIALS AND METHODS

We followed the GRADE approach by devising clinical questions and important outcomes in the Patient-Intervention-Control-Outcome (PICO) format, undertaking a systematic review, developing summary of judgements tables, and writing recommendations and rationale for each question. Each recommendation is based on the evidence found in the systematic review and, using the GRADE summary of judgement items, including desirable and undesirable effects, certainty of evidence, patient values, resources required, cost effectiveness, equity, feasibility, and acceptability, we formulated recommendations that were agreed by the authors and reviewed by independent experts and stakeholders.

RESULTS

From the results of the systematic review and evidence-to-decision making process, we were able to make 29 separate recommendations. We made a number of conditional supportive recommendations for the use of interventions to improve healing of foot ulcers in people with diabetes. These include the use of sucrose octasulfate dressings, the use of negative pressure wound therapies for post-operative wounds, the use of placental-derived products, the use of the autologous leucocyte/platelet/fibrin patch, the use of topical oxygen therapy, and the use of hyperbaric oxygen. Although in all cases it was stressed that these should be used where best standard of care was not able to heal the wound alone and where resources were available for the interventions.

CONCLUSIONS

These wound healing recommendations should support improved outcomes for people with diabetes and ulcers of the foot, and we hope that widescale implementation will follow. However, although the certainty of much of the evidence on which to base the recommendations is improving, it remains poor overall. We encourage not more, but better quality trials including those with a health economic analysis, into this area.

"Minimally Invasive" Skin Grafting With Enzymatic Debridement and Autologous Skin Cell Spray: A Retrospective Case Series

Minimally invasive surgery is becoming the standard of care across surgical subspecialties. Several new "minimally invasive" options for burn debridement and autografting exist. Enzymatic bromelain-based debridement (BBD) and autologous skin cell spray (ASCS) have independently proven to reduce the rate of split-thickness skin grafting (STSG) and decrease donor site size when grafting is performed. There is a paucity in the literature regarding the combination of these two therapies. The purpose of this study is to characterize a cohort of patients treated with both BBD and ASCS and qualitatively compare data to expected outcomes without these therapies. This retrospective study of a single academic burn center's experience using BBD and ASCS together included 13 patients with a total burn surface area (TBSA) from 1-30% and all had >50% deep partial thickness. All patients received BBD and ASCS. Deeper burns additionally received STSG with ASCS overspray. Median burn size was 14% TBSA (IQR:5.45,20), donor site size was 225 sq cm (IQR:28.5,556.5), and ratio of donor site area to total treatment area of 0.082 (IQR: 0.039, 0.241) was observed. Median observed length of stay (LOS) was 19 days (IQR:10,27), expected LOS was 15.4 days, and O/E ratio 1.06. Donor sites in both groups of patients were much smaller than expected versus treatment with conventional meshed STSG alone and length of stay is lower than expected based on burn size. An emphasis on expenses and scar development will guide future studies into the patient subset and wound features that are best for this combination treatment.

Fractional Epidermal Skin Grafts in Hard-to-Heal Wounds: Case Series

Cellutome^™ is a minimally invasive, automated system for harvesting fractional epidermal micrografts. This therapy is indicated for granulating, small size, poor exuding acute wounds. We enrolled 15 patients with 9 venous leg ulcers and 6 atypical ulcers. The micrografts were applied with a nonadherent dressing and covered with a polyurethane foam and multilayer bandage. We scheduled 3 weekly visits for the change of the secondary dressings and multilayer bandage and clinical assessment (Wound Bed Score [WBS], pain assessment, and healing rate). The lesions were measured with the Silhouette Star^™ system, a software that allows measurement of perimeter and area from a digital image. The only symptom during the procedure was a sensation of warmth. The donor area healed in 2 weeks in all patients (n = 15). We reported an area reduction of 24.30% in typical ulcers and 38.82% in atypical ulcers after 3 weeks. The average WBS improved in all ulcers from 13.06 to 14.93. The average healing rate was 0.19 mm/day both in typical and atypical ulcers. Consequently, in our small case series fractionated epidermal graft treatment significantly promoted the healing rate in all chronic ulcers regardless of etiology. Future studies with larger case series will be needed.

Translational development of ABCB5+ dermal mesenchymal stem cells for therapeutic induction of angiogenesis in non-healing diabetic foot ulcers

Background

While rapid healing of diabetic foot ulcers (DFUs) is highly desirable to avoid infections, amputations and life-threatening complications, DFUs often respond poorly to standard treatment. GMP-manufactured skin-derived ABCB5⁺ mesenchymal stem cells (MSCs) might provide a new adjunctive DFU treatment, based on their remarkable skin wound homing and engraftment potential, their ability to adaptively respond to inflammatory signals, and their wound healing-promoting efficacy in mouse wound models and human chronic venous ulcers.

Methods

The angiogenic potential of ABCB5⁺ MSCs was characterized with respect to angiogenic factor expression at the mRNA and protein level, in vitro endothelial trans-differentiation and tube formation potential, and perfusion-restoring capacity in a mouse hindlimb ischemia model. Finally, the efficacy and safety of ABCB5⁺ MSCs for topical adjunctive treatment of chronic, standard therapy-refractory, neuropathic plantar DFUs were assessed in an open-label single-arm clinical trial.

Results

Hypoxic incubation of ABCB5⁺ MSCs led to posttranslational stabilization of the hypoxia-inducible transcription factor 1α (HIF-1α) and upregulation of HIF-1α mRNA levels. HIF-1α pathway activation was accompanied by upregulation of vascular endothelial growth factor (VEGF) transcription and increase in VEGF protein secretion. Upon culture in growth factor-supplemented medium, ABCB5⁺ MSCs expressed the endothelial-lineage marker CD31, and after seeding on gel matrix, ABCB5⁺ MSCs demonstrated formation of capillary-like structures comparable with human umbilical vein endothelial cells. Intramuscularly injected ABCB5⁺ MSCs to mice with surgically induced hindlimb ischemia accelerated perfusion recovery as measured by laser Doppler blood perfusion imaging and enhanced capillary proliferation and vascularization in the ischemic muscles. Adjunctive topical application of ABCB5⁺ MSCs onto therapy-refractory DFUs elicited median wound surface area reductions from baseline of 59% (full analysis set, n = 23), 64% (per-protocol set, n = 20) and 67% (subgroup of responders, n = 17) at week 12, while no treatment-related adverse events were observed.

Conclusions

The present observations identify GMP-manufactured ABCB5⁺ dermal MSCs as a potential, safe candidate for adjunctive therapy of otherwise incurable DFUs and justify the conduct of a larger, randomized controlled trial to validate the clinical efficacy.

Trial registration: ClinicalTrials.gov, NCT03267784, Registered 30 August 2017, https://clinicaltrials.gov/ct2/show/NCT03267784

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03156-9.