Biological dermal templates with native collagen scaffolds provide guiding ridges for invading cells and may promote structured dermal wound healing

Native collagen sheet mask improves skin health and appearance: A comprehensive clinical evaluation

BACKGROUND

Collagen, a critical structural protein found abundantly in animal skin and bones, has become increasingly recognized for its potential therapeutic role in skincare. Despite growing interest, the scientific evidence for the efficacy of collagen sheet masks remains limited. The principal objective of our study was to provide insights into the multifaceted role of collagen in skin health, with a specific focus on its application in collagen sheet masks.

METHODS

The effects of a collagen sheet mask consisting of >92% native bovine collagen were investigated. The soluble protein components of the collagen matrix were analyzed and the influence of soluble collagen components on fibroblast regulation was examined. Scanning Electron Microscope (SEM) analysis was performed for structural analysis and effect on irritated skin. Five different clinical studies were conducted, including a comparison of the diversity of the skin microbiome, the tolerance and local irritating reactions in atopic dermatitis, an evaluation of skin redness after UV radiation, wrinkle reduction, and hydration and skin roughness of the collagen mask in comparison to a pre-soaked cellulose sheet mask.

RESULTS

The collagen mask contains soluble protein components, including small collagen peptides. The mask showed potential for promoting fibroblast activity. SEM analysis showed a native collagen structure similar to human dermis. The mask maintained the skin microbiome diversity and decreased skin pH levels. It demonstrated good tolerability on both intact and lesional skin and had a significant effect in reducing erythema caused by UV radiation compared to other skincare products. It showed significant improvements in skin hydration and the volume of eye wrinkles and was more effective than pre-soaked cellulose sheet masks.

CONCLUSION

Collagen sheet masks have the potential to positively impact skin health and appearance by increasing hydration, reducing erythema, minimizing wrinkles, and maintaining a healthy skin microbiome and skin barrier.

Application of a meshed artificial dermal scaffold and negative-pressure wound therapy in the treatment of full-thickness skin defects: a prospective in vivo study

Artificial dermal scaffolds (ADSs) have great value in repairing deep skin defects. However, problems such as unsatisfactory angiogenesis and local dropsy or empyema often occur, resulting in delayed or even failed wound healing. Negative pressure wound therapy (NPWT) is an effective therapy to promote wound healing or shorten wound bed preparation time. Studies on whether it can improve the effects of ADSs have never been interrupted, and no consensus has been reached. In this study, an improved ADS was prepared by mesh technology, physicochemical experiments were conducted, cell adhesion and proliferation were assessed with the meshed ADS, and in vivo experiments were conducted to investigate the effects of meshed ADS or ADS combined with NPWT in repairing full-thickness skin defects. The results showed that the meshed ADS showed through-layer channels arranged in parallel longitudinal and transverse intersections. The cell experiments confirmed the good cytocompatibility. The in vivo experiments showed that there were no differences in the take rate or contraction of grafted skin among all experiment groups. The meshed ADS exhibited good histocompatibility, and there were no differences in tissue inflammation, dermal angiogenesis, or degradation among all groups. In addition, necrosis, dropsy, or empyema of the dermal scaffold were found in all experiment groups except for the meshed ADS + NPWT group, which showed better wound repair results, including fewer scaffold-related complications and satisfactory skin graft survival and wound contraction. In conclusion, this novel meshed ADS, which has a regular through-layer mesh structure and possesses stable physicochemical properties and good biocompatibility, combined with NPWT can ensure adequate subdermal drainage and reduce the risk of scaffold-related complications, thereby improving the quality and efficiency of wound repair, promoting a broader application of biomaterials, and helping physicians and readers implement more effective wound management.

Use of a collagen-elastin matrix with split-thickness skin graft for defect coverage in complex wounds

OBJECTIVE

Severe soft tissue damage with destruction of the dermis requires plastic reconstructive treatment. For multimorbid patients or patients unable to undergo major reconstructive surgery, use of dermal substitutes, such as a collagen-elastin matrix (CEM) with a split-thickness skin graft (STSG), instead of local or free flap surgery, may be a valid and easy treatment option. We aimed to investigate and compare the outcomes and rate of successful defect reconstruction using CEM plus STSG, using either a one-step approach (simultaneous CEM and STSG) or a two-step approach (CEM and negative wound pressure therapy (NPWT), with secondary STSG transplantation).

METHOD

A single-centre, retrospective follow-up study of patients who had received CEM was conducted. Wounds had been treated with an STSG transplantation covering a CEM (MatriDerm, MedSkin Solutions Dr. Suwelack AG, Germany). Previous attempts at wound closure with conventional methods had failed in the selected patient population, which would usually have resulted in flap surgery.

RESULTS

Overall, 46 patients were included (mean age 60.9±20.0 years), with a total of 49 wound sites. We analysed 38 patients with wounds that did not require flap coverage; 18 patients received the one-step approach and 20 patients received the two-step approach. The mean follow-up in these patients was 22±11.5 months, and one patient was lost to follow-up. Overall, 29 (78.4%) wounds remained closed. Wounds which did not successfully heal were related to comorbidities, such as diabetes, alcohol misuse and smoking. Using the one-step approach, long-term defect coverage was achieved in 13 (76.5%) wounds and 16 (80.0%) wounds were closed using the two-step approach. However, there was no statistically significant differences between the one- or two-step approaches regarding the rate of development of a wound healing disorder.

CONCLUSION

Wound closure was achieved in 38 complex wounds using CEM plus STSG, while 11 wounds needed secondary flap coverage. In the flap-free wounds, there were no statistically significant differences between the one-step versus two-step approach. Using a simple defect reconstruction algorithm, we successfully used CEM plus STSG to treat complex wounds.

Microporous Polylactic Acid Scaffolds Enable Fluorescence-Based Perfusion Imaging of Intrinsic In Vivo Vascularization

In vivo tissue engineering (TE) techniques like the AV loop model provide an isolated and well-defined microenvironment to study angiogenesis-related cell interactions. Functional visualization of the microvascular network within these artificial tissue constructs is crucial for the fundamental understanding of vessel network formation and to identify the underlying key regulatory mechanisms. To facilitate microvascular tracking advanced fluorescence imaging techniques are required. We studied the suitability of microporous polylactic acid (PLA) scaffolds with known low autofluorescence to form axial vascularized tissue constructs in the AV loop model and to validate these scaffolds for fluorescence-based perfusion imaging. Compared to commonly used collagen elastin (CE) scaffolds, the total number of vessels and cells in PLA scaffolds was lower. In detail, CE-based constructs exhibited significantly higher vessel numbers on day 14 and 28 (d14: 316 ± 53; d28: 610 ± 74) compared to the respective time points in PLA-based constructs (d14: 144 ± 18; d28: 327 ± 34; each p < 0.05). Analogously, cell counts in CE scaffolds were higher compared to corresponding PLA constructs (d14: 7661.25 ± 505.93 and 5804.04 ± 716.59; d28: 11211.75 + 1278.97 and 6045.71 ± 572.72, p < 0.05). CE scaffolds showed significantly higher vessel densities in proximity to the main vessel axis compared to PLA scaffolds (200-400 µm and 600-800 µm on day 14; 400-1000 µm and 1400-1600 µm on day 28). CE scaffolds had significantly higher cell counts on day 14 at distances from 800 to 2000 µm and at distances from 400 to 1600 µm on day 28. While the total number of vessels and cells in PLA scaffolds were lower, both scaffold types were ideally suited for axial vascularization techniques. The intravascular perfusion of PLA-based constructs with fluorescence dye MHI148-PEI demonstrated dye specificity against vascular walls of low- and high-order branches as well as capillaries and facilitated the fluorescence-based visualization of microcirculatory networks. Fluorophore tracking may contribute to the development of automated quantification methods after 3D reconstruction and image segmentation. These technologies may facilitate the characterization of key regulators within specific subdomains and add to the current understanding of vessel formation in axially vascularized tissue constructs.

Zinc oxide loaded chitosan-elastin-sodium alginate nanocomposite gel using freeze gelation for enhanced adipose stem cell proliferation and antibacterial properties

Hydrogels have been the material of choice for regenerative medicine applications due to their biocompatibility that can facilitate cellular attachment and proliferation. The present study aimed at constructing a porous hydrogel composite scaffold (chitosan, sodium alginate and elastin) for the repair of chronic skin wounds. Chitosan-based hydrogel incorporating varying concentrations of zinc oxide nanoparticles i.e. ZnO-NPs (0, 0.001, 0.01, 0.1 and 1 % w/w) as the antimicrobial agent tested against Escherichia coli (E.coli) and Staphylococcus aureus (S. aureus) exhibited good antibacterial activities. ZnO-NPs were characterized by UV visible spectroscopy, Scanning electron microscopy (SEM) analysis, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. Fabricated gels were characterized by SEM analysis, FTIR, XRD, swelling ratio, degradation behavior and controlled release kinetics of ZnO-NPs. In vitro cytocompatibility of the composite was investigated using human adipose stem cells (ADSCs) by MTT and lactate dehydrogenase (LDH) assay, further assessed by SEM analysis and PKH26 staining. The SEM and XRD analysis confirmed the successful loading of ZnO-NPs into these scaffolds. Fluorescence PKH26 stained images and SEM analysis of ADSCs seeded scaffolds revealed biocompatible nature. The findings suggested that the developed composite gels have potential clinically for tissue engineering and chronic wound treatment.

Alginate-Based Hydrogels and Scaffolds for Biomedical Applications

Alginate is a natural polymer of marine origin and, due to its exceptional properties, has great importance as an essential component for the preparation of hydrogels and scaffolds for biomedical applications. The design of biologically interactive hydrogels and scaffolds with advanced, expected and required properties are one of the key issues for successful outcomes in the healing of injured tissues. This review paper presents the multifunctional biomedical applications of alginate-based hydrogels and scaffolds in selected areas, highlighting the key effect of alginate and its influence on the essential properties of the selected biomedical applications. The first part covers scientific achievements for alginate in dermal tissue regeneration, drug delivery systems, cancer treatment, and antimicrobials. The second part is dedicated to our scientific results obtained for the research opus of hydrogel materials for scaffolds based on alginate in synergy with different materials (polymers and bioactive agents). Alginate has proved to be an exceptional polymer for combining with other naturally occurring and synthetic polymers, as well as loading bioactive therapeutic agents to achieve dermal, controlled drug delivery, cancer treatment, and antimicrobial purposes. Our research was based on combinations of alginate with gelatin, 2-hydroxyethyl methacrylate, apatite, graphene oxide and iron(III) oxide, as well as curcumin and resveratrol as bioactive agents. Important features of the prepared scaffolds, such as morphology, porosity, absorption capacity, hydrophilicity, mechanical properties, in vitro degradation, and in vitro and in vivo biocompatibility, have shown favorable properties for the aforementioned applications, and alginate has been an important link in achieving these properties. Alginate, as a component of these systems, proved to be an indispensable factor and played an excellent “role” in the optimal adjustment of the tested properties. This study provides valuable data and information for researchers and demonstrates the importance of the role of alginate as a biomaterial in the design of hydrogels and scaffolds that are powerful medical “tools” for biomedical applications.

Treatment of complex extremity wounds with MatriDerm: first clinical experience in the US

OBJECTIVE

Coverage of upper and lower extremity wounds with exposed vital structures such as tendon and bone is reliant on pedicled and free flaps. However, a population of patients with medical comorbidities or other social issues may not be suitable for flap coverage. We present the first in patient clinical experience in the US with MatriDerm (Billerbeck, Germany) for treatment of difficult extremity wounds, all with exposed bone or tendon.

METHOD

MatriDerm dermal matrix has been popular in Europe for coverage of wounds. However, MatriDerm only received full approval for use by the US Food and Drug Administration (FDA) in 2021. Here we review our clinical experience.

RESULTS

Locations (n=11) treated included forearm (n=1), hand (n=4), leg (n=3), and feet (n=3). Vital structures in wounds exposed included bone (n=3), bone and tendon (n=1), and tendon (n=7). Mean area of the wound treated was 59.2cm² (range: 2 to 230). In our series, eight out of 11 wounds healed, with MatriDerm only (n=6) or following delayed skin grafting (n=2). Mean time to healing in the patients treated only with MatriDerm was 49 days (range 7 to 84). Mean time to split-thickness skin grafting in the remaining two patients was 44.5 days (range 32 to 57).

CONCLUSION

MatriDerm has potential for treatment of complex extremity wounds, which would otherwise require flap coverage, in patients who are not good candidates for flap surgery.

Quaternary ammonium salt-modified isabgol scaffold as an antibacterial dressing to improve wound healing

Chronic wounds require suitable treatment and management strategies for proper healing. Among other causes, infection delays the healing of wounds and increases the risk of wound-related complications. In this study, an inherently antibacterial and biocompatible wound dressing is developed to enhance the healing. Chemical modification of a natural polysaccharide, Isabgol with epoxypropyltrimethylammonium chloride, renders antibacterial activity to the material. This is the first report of such chemical modification of this polymer for biomedical applications. The modified material is freeze-dried to obtain porous scaffolds. ¹³C NMR and FTIR analysis confirmed the modification of the Isabgol polymer chains with EPTMAC. SEM analysis confirmed the porous structure of the scaffold that would allow the exchange of gases and nutrients through the matrix. The material can swell up to 17 times its initial weight, allowing it to absorb wound exudates and maintain a moist environment at the wound site. Thermogravimetric analysis and compression testing showed that the scaffold has suitable thermal and mechanical properties. The material is antibacterial and can potentially prevent infections at the wound site. In vitro studies have confirmed that these scaffolds are cytocompatible and hemocompatible. These properties indicate that the EPTMAC-modified Isabgol scaffolds would be suitable for wound dressing applications.

Immuno-modulatory biomaterials as anti-inflammatory therapeutics

Biocompatible and biodegradable biomaterials are used extensively in regenerative medicine and serve as a tool for tissue replacement, as a platform for regeneration of injured tissue, and as a vehicle for delivery of drugs. One of the key factors that must be addressed in developing successful biomaterial-based therapeutics is inflammation. Whilst inflammation is initially essential for wound healing; bringing about clearance of debris and infection, prolonged inflammation can result in delayed wound healing, rejection of the biomaterial, further tissue damage and increased scarring and fibrosis. In this context, the choice of biomaterial must be considered carefully to minimise further induction of inflammation. Here we address the ability of the biomaterials themselves to modulate inflammatory responses and outline how the physico-chemical properties of the materials impact on their pro and anti-inflammatory properties (Fig. 1).

Comparison of Efficacy among Three Dermal Substitutes in the Management of Critical Lower-Limb Wounds: The Largest Biases-Reduced Single-Center Retrospective Cohort Study in Literature

Background and objectives: The skin recently became the main focus of regenerative medicine and, in this context, skin substitutes are fully entering into the plastic surgeon’s armamentarium. Among the various types of skin substitutes, dermal substitutes (DSs) are the most used. Our study aims to retrospectively compare three renowned and extremely similar DS in the management of critical lower limb wounds in the largest cohort analysis currently present in literature. Materials and Methods: We followed a strict protocol of application and evaluation of the DS for each patient and wound and, after a meticulous bias reduction process, we compared final outcomes in terms of efficacy and speed in achieving the defect coverage. Results: Among patients who did not receive a skin graft after the DS, we registered a wound healed surface of 50% for Pelnac, 52% for Integra, and 19% for Nevelia, after 30 days from the external silicon layer removal; among those who received a skin graft after the DS, we observed a significantly lower mean percentage of graft take after 7 days with Pelnac (53%) compared to Integra and Nevelia (92% and 80%, respectively). The overall percentage of wound healed surface obtained after 30 days from the external silicon sheet removal, either with or without skin graft, was 71% for Pelnac, 63% for Integra and 63% for Nevelia. We also ran a sub-group analysis only including grafted wounds with a negative microbiological test and the mean percentage of graft take was similar this time. Eventually, we assessed the influence of the wound’s “chronicity” on its healing, comparing the mean graft take only in “acute” wounds who received a skin graft and it resulted 63% for Pelnac, 91% for Integra and 75% for Nevelia. Conclusions: Integra demonstrates the highest rate of skin graft viability and the highest rate of skin graft takes after 7 days. Pelnac shows the quickest induction of secondary healing in acute wounds. Nevelia is not different from Integra and shows a superior graft take compared to Pelnac, but features the lowest secondary healing induction rate. No differences exist between the three DSs in terms of wound healing after 30 days from the skin graft or from the removal of the external silicon layer.

Current Insights into Collagen Type I

Collagen type I (Col-I) is unique due to its high biocompatibility in human tissue. Despite its availability from various sources, Col-I naturally mimics the extracellular matrix (ECM) and generally makes up the larger protein component (90%) in vasculature, skin, tendon bone, and other tissue. The acceptable physicochemical properties of native Col-I further enhance the incorporation of Col-I in various fields, including pharmaceutical, cosmeceutical, regenerative medicine, and clinical. This review aims to discuss Col-I, covering the structure, various sources of availability, native collagen synthesis, current extraction methods, physicochemical characteristics, applications in various fields, and biomarkers. The review is intended to provide specific information on Col-I currently available, going back five years. This is expected to provide a helping hand for researchers who are concerned about any development on collagen-based products particularly for therapeutic fields.

Natural-Based Biomaterial for Skin Wound Healing (Gelatin vs. Collagen): Expert Review

Collagen (Col) and gelatin are most extensively used in various fields, particularly in pharmaceuticals and therapeutics. Numerous researchers have proven that they are highly biocompatible to human tissues, exhibit low antigenicity and are easy to degrade. Despite their different sources both Col and gelatin have almost the same effects when it comes to wound healing mechanisms. Considering this, the bioactivity and biological effects of both Col and gelatin have been, and are being, constantly investigated through in vitro and in vivo assays to obtain maximum outcomes in the future. With regard to their proven nutritional values as sources of protein, Col and gelatin products exert various possible biological activities on cells in the extracellular matrix (ECM). In addition, a vast number of novel Col and gelatin applications have been discovered. This review compared Col and gelatin in terms of their structures, sources of derivatives, physicochemical properties, results of in vitro and in vivo studies, their roles in wound healing and the current challenges in wound healing. Thus, this review provides the current insights and the latest discoveries on both Col and gelatin in their wound healing mechanisms.

Cellular human tissue-engineered skin substitutes investigated for deep and difficult to heal injuries

Wound healing is an important function of skin; however, after significant skin injury (burns) or in certain dermatological pathologies (chronic wounds), this important process can be deregulated or lost, resulting in severe complications. To avoid these, studies have focused on developing tissue-engineered skin substitutes (TESSs), which attempt to replace and regenerate the damaged skin. Autologous cultured epithelial substitutes (CESs) constituted of keratinocytes, allogeneic cultured dermal substitutes (CDSs) composed of biomaterials and fibroblasts and autologous composite skin substitutes (CSSs) comprised of biomaterials, keratinocytes and fibroblasts, have been the most studied clinical TESSs, reporting positive results for different pathological conditions. However, researchers' purpose is to develop TESSs that resemble in a better way the human skin and its wound healing process. For this reason, they have also evaluated at preclinical level the incorporation of other human cell types such as melanocytes, Merkel and Langerhans cells, skin stem cells (SSCs), induced pluripotent stem cells (iPSCs) or mesenchymal stem cells (MSCs). Among these, MSCs have been also reported in clinical studies with hopeful results. Future perspectives in the field of human-TESSs are focused on improving in vivo animal models, incorporating immune cells, designing specific niches inside the biomaterials to increase stem cell potential and developing three-dimensional bioprinting strategies, with the final purpose of increasing patient's health care. In this review we summarize the use of different human cell populations for preclinical and clinical TESSs under research, remarking their strengths and limitations and discuss the future perspectives, which could be useful for wound healing purposes.

Mimicking the Hierarchical Organization of Natural Collagen: Toward the Development of Ideal Scaffolding Material for Tissue Regeneration

Biological materials found in living organisms, many of which are proteins, feature a complex hierarchical organization. Type I collagen, a fibrous structural protein ubiquitous in the mammalian body, provides a striking example of such a hierarchical material, with peculiar architectural features ranging from the amino acid sequence at the nanoscale (primary structure) up to the assembly of fibrils (quaternary structure) and fibers, with lengths of the order of microns. Collagen plays a dominant role in maintaining the biological and structural integrity of various tissues and organs, such as bone, skin, tendons, blood vessels, and cartilage. Thus, "artificial" collagen-based fibrous assemblies, endowed with appropriate structural properties, represent ideal substrates for the development of devices for tissue engineering applications. In recent years, with the ultimate goal of developing three-dimensional scaffolds with optimal bioactivity able to promote both regeneration and functional recovery of a damaged tissue, numerous studies focused on the capability to finely modulate the scaffold architecture at the microscale and the nanoscale in order to closely mimic the hierarchical features of the extracellular matrix and, in particular, the natural patterning of collagen. All of these studies clearly show that the accurate characterization of the collagen structure at the submolecular and supramolecular levels is pivotal to the understanding of the relationships between the nanostructural/microstructural properties of the fabricated scaffold and its macroscopic performance. Several studies also demonstrate that the selected processing, including any crosslinking and/or sterilization treatments, can strongly affect the architecture of collagen at various length scales. The aim of this review is to highlight the most recent findings on the development of collagen-based scaffolds with optimized properties for tissue engineering. The optimization of the scaffolds is particularly related to the modulation of the collagen architecture, which, in turn, impacts on the achieved bioactivity.

A hybrid scaffold of gelatin glycosaminoglycan matrix and fibrin as a carrier of human corneal fibroblast cells

A hybrid scaffold of gelatin-glycosaminoglycan matrix and fibrin (FGG) has been synthesized to improve the mechanical properties, degradation time and cell response of fibrin-like scaffolds. The FGG scaffold was fabricated by optimizing some properties of fibrin-only gel and gelatin-glycosaminoglycan (GG) scaffolds. Mechanical analysis of optimized fibrin-only gel showed the Young module and tensile strength of up to 72 and 121 KPa, respectively. Significantly, the nine-fold increase in the Young modulus and a seven-fold increase in tensile strength was observed when fibrin reinforced with GG scaffold. Additionally, the results demonstrated that the degradation time of fibrin was enhanced successfully up to 7 days which was much longer time compared to fibrin-only gel with 38 h of degradation time. More than 45% of FGG initial mass was preserved on day 7 in the presence of aprotinin. Human corneal fibroblast cells (HCFCs) were seeded on the FGG, fibrin-only gel and GG scaffolds for 5 days. The FGG scaffold showed excellent cell viability over 5 days, and the proliferation of HCFCs also increased significantly in comparison with fibrin-only gel and GG scaffolds. The FGG scaffold illustrates the great potential to use in which appropriate stability and mechanical properties are essential to tissue functionality.

Biological dermal templates with native collagen scaffolds provide guiding ridges for invading cells and may promote structured dermal wound healing

Dermal substitutes are of major importance in treating full thickness skin defects. They come in a variety of materials manufactured into various forms, such as films, hydrocolloids, hydrogels, sponges, membranes, and electrospun micro- and nanofibers. Bioactive dermal substitutes act in wound healing either by delivery of bioactive compounds or by being constructed from materials having endogenous activity. The healing success rate is highly determined by cellular and physiological processes at the host-biomaterial interface during crucial wound healing steps. Hence, it is important to design appropriate wound treatment strategies with the ability to work actively with tissues and cells to enhance healing. Therefore, in this study, we investigated biological dermal templates and their potential to stimulate natural cell adherence, guidance, and morphology. The most pronounced effect was observed in biomaterials with the highest content of native collagen networks. Cell attachment and proliferation were significantly enhanced on native collagen scaffolds. Cell morphology was more asymmetrical on such scaffolds, resembling native in vivo structures. Importantly, considerably lower expression of myofibroblast phenotype was observed on native collagen scaffolds. Our data suggest that this treatment strategy might be beneficial for the wound environment, with the potential to promote improved tissue regeneration and reduce abnormal scar formation.