A Novel Collagen-Gelatin Scaffold for the Treatment of Deep Dermal Wounds—An Evaluation in a Minipig Model

The Goettingen minipig as an experimental model in wound-healing studies

Background

Deep dermal wounds in extensive burns and chronic wound-healing disorders represent a significant medical problem and require a high level of therapy to reduce the risk of infection and other long-term consequences, such as amputation. A better understanding of the wound-healing processes is essential, and animal models are indispensable to fundamental research.

Objective

This study aimed to provide a transparent protocol and prove the effectiveness of an in vivo porcine model using Goettingen minipigs for wound-healing studies.

Material and methods

Thirteen female Goettingen minipigs were kept in species-appropriate housing and were treated according to the German law for the protection of animals. The study was performed with permission from the local ethical review committee of animal welfare. The experimental procedure for studying dermal regeneration in 102 full-thickness wounds through clinical observation and histological analysis, focusing on neodermal formation, is described in detail.

Results

The Goettingen minipig model proved to be suitable in wound-healing studies. The dermal regeneration was evident and viewable without wound contamination or any rejection reaction. The histological evaluations were also reliable and clearly presented the optimized wound healing of deep dermal wounds using the different therapeutic approaches.

Conclusion

Given the great clinical need for alternative or complementary therapies, we considered the Goettingen minipig trial a reliable, ethically justifiable, effective, and reproducible in vivo model for wound-healing studies.

Mesenchymal stem cell therapy in diabetic foot ulcer: An updated comprehensive review

Background

Diabetes has evolved into a worldwide public health issue. One of the most serious complications of diabetes is diabetic foot ulcer (DFU), which frequently creates a significant financial strain on patients and lowers their quality of life. Up until now, there has been no curative therapy for DFU, only symptomatic relief or an interruption in the disease's progression. Recent studies have focused attention on mesenchymal stem cells (MSCs), which provide innovative and potential treatment candidates for several illnesses as they can differentiate into various cell types. They are mostly extracted from the placenta, adipose tissue, umbilical cord (UC), and bone marrow (BM). Regardless of their origin, they show comparable features and small deviations. Our goal is to investigate MSCs' therapeutic effects, application obstacles, and patient benefit strategies for DFU therapy.

Methodology

A comprehensive search was conducted using specific keywords relating to DFU, MSCs, and connected topics in the databases of Medline, Scopus, Web of Science, and PubMed. The main focus of the selection criteria was on English-language literature that explored the relationship between DFU, MSCs, and related factors.

Results and Discussion

Numerous studies are being conducted and have demonstrated that MSCs can induce re-epithelialization and angiogenesis, decrease inflammation, contribute to immunological modulation, and subsequently promote DFU healing, making them a promising approach to treating DFU. This review article provides a general snapshot of DFU (including clinical presentation, risk factors and etiopathogenesis, and conventional treatment) and discusses the clinical progress of MSCs in the management of DFU, taking into consideration the side effects and challenges during the application of MSCs and how to overcome these challenges to achieve maximum benefits.

Conclusion

The incorporation of MSCs in the management of DFU highlights their potential as a feasible therapeutic strategy. Establishing a comprehensive understanding of the complex relationship between DFU pathophysiology, MSC therapies, and related obstacles is essential for optimizing therapy outcomes and maximizing patient benefits.

Cell-loaded genipin cross-linked collagen/gelatin skin substitute adorned with zinc-doped bioactive glass-ceramic for cutaneous wound regeneration

An optimal tissue-engineered dermal substitute should possess biocompatibility and cell adhesion conduction to facilitate fibroblast and keratinocyte infiltration and proliferation, as well as angiogenesis potential to escalate wound healing. Zinc was doped to bioactive glass-ceramic (Zn-BGC) to promote biocompatibility and angiogenesis properties. Zn-BGC was then incorporated into a collagen (Col) and gelatin (Gel) porous scaffold. The bioactive porous bionanocomposite exhibited biocompatibility along with improved cell attachment and proliferation. Scaffolds including Col-Gel/Zn-BGC with or without mouse embryonic fibroblasts were applied on full-thickness skin wounds on the BALB/c mice to assess their wound healing potential in vivo. The results indicated that the biodegradation rate of the Col-Gel/Zn-BGC nanocomposites was comparable to the rate of skin tissue regeneration in vivo. Macroscopic wound healing results showed that Col-Gel/Zn-BGC loaded with mouse embryonic fibroblast possesses the smallest wound size, indicating the fastest healing process. Histopathological evaluations displayed that the optimal wound regeneration was observed in Col-Gel/Zn-BGC nanocomposites loaded with mouse embryonic fibroblasts indicated by epithelialization and angiogenesis; besides the number of fibroblasts and hair follicles was increased. The bioactive nanocomposite scaffold of Col-Gel containing Zn-BGC nanoparticles loaded with mouse embryonic fibroblasts can be employed as a desirable skin substitute to ameliorate cutaneous wound regeneration.

Stem Cell-Based Therapy: A Promising Treatment for Diabetic Foot Ulcer

Diabetic foot ulcer (DFU) is a severe complication of diabetes and a challenging medical condition. Conventional treatments for DFU have not been effective enough to reduce the amputation rates, which urges the need for additional treatment. Stem cell-based therapy for DFU has been investigated over the past years. Its therapeutic effect is through promoting angiogenesis, secreting paracrine factors, stimulating vascular differentiation, suppressing inflammation, improving collagen deposition, and immunomodulation. It is controversial which type and origin of stem cells, and which administration route would be the most optimal for therapy. We reviewed the different types and origins of stem cells and routes of administration used for the treatment of DFU in clinical and preclinical studies. Diabetes leads to the impairment of the stem cells in the diseased patients, which makes it less ideal to use autologous stem cells, and requires looking for a matching donor. Moreover, angioplasty could be complementary to stem cell therapy, and scaffolds have a positive impact on the healing process of DFU by stem cell-based therapy. In short, stem cell-based therapy is promising in the field of regenerative medicine, but more studies are still needed to determine the ideal type of stem cells required in therapy, their safety, proper dosing, and optimal administration route.

Assessment of Two Commonly used Dermal Regeneration Templates in a Swine Model without Skin Grafting

In the medical care of partial and full-thickness wounds, autologous skin grafting is still the gold standard of dermal replacement. In contrast to spontaneous reepithelializing of superficial wounds, deep dermal wounds often lead to disturbing scarring, with cosmetically or functionally unsatisfactory results. However, modern wound dressings offer promising approaches to surface reconstruction. Against the background of our future aim to develop an innovative skin substitute, we investigated the behavior of two established dermal substitutes, a crosslinked and a non-crosslinked collagen biomatrix. The products were applied topically on a total of 18 full-thickness skin defects paravertebrally on the back of female Göttingen Minipigs—six control wounds remained untreated. The evaluation was carried out planimetrically (wound closure time) and histologically (neoepidermal cell number and epidermis thickness). Both treatment groups demonstrated significantly faster reepithelialization than the controls. The histologic examination verified the highest epidermal thickness in the crosslinked biomatrix-treated wounds, whereas the non-crosslinked biomatrix-treated wounds showed a higher cell density. Our data presented a positive influence on epidermal regeneration with the chosen dermis substitutes even without additional skin transplantation and, thus, without additional donor site morbidity. Therefore, it can be stated that the single biomatrix application might be used in a clinical routine with small wounds, which needs to be investigated further in a clinical setting to determine the size and depths of a suitable wound bed. Nevertheless, currently available products cannot solely achieve wound healing that is equal to or superior to autologous tissue. Thus, the overarching aim still is the development of an innovative skin substitute to manage surface reconstruction without additional skin grafting.

The Topical Effect of rhGDF-5 Embedded in a Collagen–Gelatin Scaffold for Accelerated Wound Healing

The application of exogenous growth factors such as the recombinant human growth and differentiation factor 5 (rhGDF-5) represents a major research topic with great potential for the treatment of complex wounds. In a randomized, controlled minipig study, the topical effect of rhGDF-5 on full-thickness skin defects was evaluated. A total of 60 deep dermal wounds were either treated with rhGDF-5 embedded in an innovative collagen scaffold or another commonly used collagen matrix or left untreated. Wound healing was analyzed by planimetric analysis to determine wound closure over time. After 21 days, the areas of the initial wounds were excised, and the newly formed tissue was examined histologically. In comparison to untreated wounds, all examined matrices accelerated dermal wound healing. The largest acceleration of wound healing was seen with the high-dose rhGDF-5-treated wounds, which, compared to the untreated wounds, accelerated wound healing by 2.58 days, improved the neoepidermal thickness by 32.40 µm, and increased the epidermal cell density by 44.88 cells. The innovative collagen scaffold delivered rhGDF-5 adequately, served as a template to guide proliferating and restructuring cells, and accelerated wound healing. Thus, this composite product offers a novel tool for developing effective wound dressings in regenerative medicine.

Autologous Stem Cell Therapy for Chronic Lower Extremity Wounds: A Meta-Analysis of Randomized Controlled Trials

Lower extremity chronic wounds (LECWs) commonly occur in patients with diabetes mellitus (DM) and peripheral arterial disease (PAD). Autologous stem cell therapy (ASCT) has emerged as a promising alternative treatment for those who suffered from LECWs. The purpose of this study was to assess the effects of ASCT on LECWs. Two authors searched three core databases, and independently identified evidence according to predefined criteria. They also individually assessed the quality of the included randomized controlled trials (RCTs), and extracted data on complete healing rate, amputation rate, and outcomes regarding peripheral circulation. The extracted data were pooled using a random-effects model due to clinical heterogeneity among the included RCTs. A subgroup analysis was further performed according to etiology, source of stem cells, follow-up time, and cell markers. A total of 28 RCTs (n = 1096) were eligible for this study. The pooled results showed that patients receiving ASCT had significantly higher complete healing rates (risk ratio (RR) = 1.67, 95% confidence interval (CI) 1.28–2.19) as compared with those without ASCT. In the CD34+ subgroup, ASCT significantly led to a higher complete healing rate (RR = 2.70, 95% CI 1.50–4.86), but there was no significant difference in the CD34− subgroup. ASCT through intramuscular injection can significantly improve wound healing in patients with LECWs caused by either DM or critical limb ischemia. Lastly, CD34+ is an important cell marker for potential wound healing. However, more extensive scale and well-designed studies are necessary to explore the details of ASCT and chronic wound healing.

Evaluation of a cross-linked versus non-cross-linked collagen matrix in full-thickness skin defects

Autologous skin transplantation is the gold standard for treatment of full-thickness skin defects such as deep burn injuries, but has the disadvantages of limited donor sites and donor site morbidities. Alternative skin replacement products, such as xenografts and allografts, are not a permanent solution. Numerous manufactured skin substitutes already show promising approaches, but have limited efficacy. Therefore, wound dressings adaptable to the physiology of wound healing are still needed. In a randomized controlled in vivo study, a newly designed biocompatible collagen nonwoven matrix was compared to the Integra® bilayer dermal substitute and untreated controls in 48 full-thickness skin defects in a swine model. The take of all templates was complete, and all the tissue-engineered products accelerated dermal wound healing compared to the untreated controls, as identified by planimetric measurements. The higher collagen dose treatments and Integra®-covered wounds developed the thickest, cell-rich neoepidermal tissue in histological examination. The innovative biocompatible collagen matrix is flexibly applicable and modifiable, and offers potential as a carrier membrane for therapeutic supplemental products such as growth factors to further develop effective wound dressings.

Natural composite dressings based on collagen, gelatin and plant bioactive compounds for wound healing: A review

Skin wound dressings are commonly used to stimulate and enhance skin tissue repair. Even if wounds seem easy to repair for clinicians and to replicate in an in vitro set-up for scientists, chronic wounds remain currently an open challenge in skin tissue engineering for patients with complementary diseases. The seemingly simple process of skin healing hides a heterogenous sequence of events, specific timing, and high level of organization and coordination among the involved cell types. Taken together, all these aspects make wound healing a unique process, but we are not yet able to completely repair the chronic wounds or to reproduce them in vitro with high fidelity. This review highlights the main characteristics and properties of a natural polymer, which is widely used as biomaterial, namely collagen and of its denatured form, gelatin. Available wound dressings based on collagen/gelatin and proposed variants loaded with bioactive compounds derived from plants are presented. Applications of these composite biomaterials are discussed with emphasis on skin wound healing. A perspective on current issues is given in the light of future research. The emerging technologies support the development of innovative dressings based exclusively on natural constituents, either polymeric or bioactive compounds.