Modern collagen wound dressings: function and purpose

l-Carnosine loaded on carboxymethyl cellulose hydrogels for promoting wound healing

Wound management remains a challenge in clinical practice. Nowadays, patients have an increasing demand for wound repair with enhanced speed and quality; therefore, there is a great need to seek therapeutic strategies that can promote rapid and effective wound healing. In this study, we developed a carboxymethyl cellulose hydrogel loaded with l-carnosine (CRN@hydrogel) for potential application as a wound dressing. In vitro experiments confirmed that CRN@hydrogel can release over 80% of the drug within 48 h and demonstrated its favorable cytocompatibility and blood compatibility, thus establishing its applicability for safe utilization in clinical practice. Using a rat model, we found that this hydrogel could promote and accelerate wound healing more effectively. These results indicate that the novel hydrogel can serve as an efficient therapeutic strategy for wound treatment.

Minimizing pain in deer antler removal: Local anaesthetics in ZnO nanoparticle based collagen dressings as a promising solution

Antler removal in deer is a common practice for various purposes, including meat production and traditional medicine. However, the current industry practice using lidocaine as a local anesthetic has limitations, such as short duration of action and the potential for postoperative infections. In this study, we investigated the performance of a ZnO collagen nanocomposites loaded with local anesthetics to improve wound management and alleviate pain associated with antler removal in red deer. The research involved the preparation of collagen nanocomposites with local anesthetics and testing the drug release rates using in vitro drug release tests. Pharmacokinetic analysis was performed to evaluate the total drug release from the collagen matrix in red deer after velvet removal. Additionally, the analgesic efficacy of these collagen nanocomposite dressings was assessed after antler removal in red deer. Functionalized ZnO nanoparticles were incorporated into collagen fibers to enhance their mechanical stability and prolong drug release. The developed collagen nanocomposites aimed to slowly release local anesthetics and promote wound healing. The findings of this research could have significant implications for improving the pain management and wound healing associated with antler removal in deer. The results obtained from the in vitro drug release tests, pharmacokinetic analysis, and analgesic efficacy evaluations provide valuable insights into the understanding and development of novel approaches for antler removal procedures in red deer. The findings contribute to the advancement of knowledge in this field and lay the foundation for future implementation of improved techniques and protocols for antler removal.

Selection of collagen IV fragments forming the outer sphere of the native protein: Assessment of biological activity for regenerative medicine

The aim of this research was to select the fragments that make up the outer layer of the collagen IV (COL4A6) protein and to assess their potential usefulness for regenerative medicine. It was expected that because protein-protein interactions take place via contact between external domains, the set of peptides forming the outer sphere of collagen IV will determine its interaction with other proteins. Cellulose-immobilized protein fragment libraries treated with polyclonal anti-collagen IV antibodies were used to select the peptides forming the outer sphere of collagen IV. In the first test, 33 peptides that strongly interacted with the polyclonal anti-collagen IV antibodies were selected from a library of non-overlapping fragments of collagen IV. The selected fragments of collagen IV (cleaved from the cellulose matrix) were tested for their cytotoxicity, their effects on cell viability and proliferation, and their impact on the formation of reactive oxygen species (ROS). The studies used RAW 264.7 mouse macrophage cells and Hs 680.Tr human fibroblasts. PrestoBlue, ToxiLight™, and ToxiLight 100% Lysis Control assays were conducted. The viability of fibroblasts cultured with the addition of increasing concentrations of the peptide mix did not show statistically significant differences from the control. Fragments 161-170, 221-230, 721-730, 1331-1340, 1521-1530, and 1661-1670 of COL4A6 were examined for cytotoxicity against BJ normal human foreskin fibroblasts. None of the collagen fragments were found to be cytotoxic. Further research is underway on the potential uses of collagen IV fragments in regenerative medicine.

A fetal wound healing program after intrauterine bile duct injury may contribute to biliary atresia

BACKGROUND & AIMS

Biliary atresia (BA) is an obstructive cholangiopathy that initially affects the extrahepatic bile ducts (EHBDs) of neonates. The etiology is uncertain, but evidence points to a prenatal cause. Fetal tissues have increased levels of hyaluronic acid (HA), which plays an integral role in fetal wound healing. The objective of this study was to determine whether a program of fetal wound healing is part of the response to fetal EHBD injury.

METHODS

Mouse, rat, sheep, and human EHBD samples were studied at different developmental time points. Models included a fetal sheep model of prenatal hypoxia, human BA EHBD remnants and liver samples taken at the time of the Kasai procedure, EHBDs isolated from neonatal rats and mice, and spheroids and other models generated from primary neonatal mouse cholangiocytes.

RESULTS

A wide layer of high molecular weight HA encircling the lumen was characteristic of the normal perinatal but not adult EHBD. This layer, which was surrounded by collagen, expanded in injured ducts in parallel with extensive peribiliary gland hyperplasia, increased mucus production and elevated serum bilirubin levels. BA EHBD remnants similarly showed increased HA centered around ductular structures compared with age-appropriate controls. High molecular weight HA typical of the fetal/neonatal ducts caused increased cholangiocyte spheroid growth, whereas low molecular weight HA induced abnormal epithelial morphology; low molecular weight HA caused matrix swelling in a bile duct-on-a-chip device.

CONCLUSION

The fetal/neonatal EHBD, including in human EHBD remnants from Kasai surgeries, demonstrated an injury response with prolonged high levels of HA typical of fetal wound healing. The expanded peri-luminal HA layer may swell and lead to elevated bilirubin levels and obstruction of the EHBD.

IMPACT AND IMPLICATIONS

Biliary atresia is a pediatric cholangiopathy associated with high morbidity and mortality rates; although multiple etiologies have been proposed, the fetal response to bile duct damage is largely unknown. This study explores the fetal pathogenesis after extrahepatic bile duct damage, thereby opening a completely new avenue to study therapeutic targets in the context of biliary atresia.

Box-Behnken design to optimize the cross-linked sodium alginate/mucilage/Aloe vera film: Physical and mechanical studies

The crosslinked sodium alginate/mucilage/Aloe vera/glycerin was optimized by different ratios of each factor to be an absorption wound dressing base for infected wound healing. Mucilage was extracted from seeds of Ocimum americanum. The Box-Behnken design (BBD) in response surface methodology (RSM) was used to construct an optimal wound dressing base with the target ranges of mechanical and physical properties of each formulation. The independent variables selected were sodium alginate (X1: 0.25-0.75 g), mucilage (X2: 0.00-0.30 g), Aloe vera (X3: 0.00-0.30 g), and glycerin (X4: 0.00-1.00 g). The dependent variables were tensile strength (Y1: low value), elongation at break (Y2: high value), Young's modulus (Y3: high value), swelling ratio (Y4: high value), erosion (Y5: low value), and moisture uptake (Y6: high value). The results showed that the wound dressing base with the most desirable response consists of sodium alginate (59.90 % w/w), mucilage (23.96 % w/w), and glycerin (16.14 % w/w) without Aloe vera gel powder (0.00 % w/w).

Therapeutic Potential of Nanocarrier-Mediated Delivery of Phytoconstituents for Wound Healing: Their Current Status and Future Perspective

The treatment of wounds is a serious problem all over the world and imposes a huge financial burden on each and every nation. For a long time, researchers have explored wound dressing that speeds up wound healing. Traditional wound dressing does not respond effectively to the wound-healing process as expected. Therapeutic active derived from plant extracts and extracted bioactive components have been employed in various regions of the globe since ancient times for the purpose of illness, prevention, and therapy. About 200 years ago, most medical treatments were based on herbal remedies. Especially in the West, the usage of herbal treatments began to wane in the 1960s as a result of the rise of allopathic medicine. In recent years, however, there has been a resurgence of interest in and demand for herbal medicines for a number of reasons, including claims about their efficacy, shifting consumer preferences toward natural medicines, high costs and negative side effects of modern medicines, and advancements in herbal medicines brought about by scientific research and technological innovation. The exploration of medicinal plants and their typical uses could potentially result in advanced pharmaceuticals that exhibit reduced adverse effects. This review aims to present an overview of the utilization of nanocarriers in plant-based therapeutics, including its current status, recent advancements, challenges, and future prospects. The objective is to equip researchers with a comprehensive understanding of the historical background, current state, and potential future developments in this emerging field. In light of this, the advantages of nanocarriers based delivery of natural wound healing treatments have been discussed, with a focus on nanofibers, nanoparticles, nano-emulsion, and nanogels.

In vitro and in vivo effect of novel GA-CSNPs loaded col-fibrin nanocomposite scaffold on diabetic wound healing

A non-healing wound is a common problem associated with diabetes mellitus. Chronic inflammation, challenging re-epithelization, unusual growth factors, and impaired angiogenesis are the multifactorial events that contribute to impaired wounds. Hence, in the present work, an innovative GA-CSNPs nanocomposite scaffold has been fabricated by integrating Gallic acid (GA) loaded chitosan nanoparticles (GA-CSNPs) into a genipin crosslinked collagen-fibrin (Col-fibrin) scaffold as wound dressing material. The in vitro RT-PCR study carried out using NIH/3T3 mouse fibroblast cells showed that treatment with GA-CSNPs nanocomposite scaffold aids in an upsurge in the expression of Col-I, III, and VEGF, which further supports the synthesis of extracellular matrix, increases neovascularization and development of the established vascular system. In vivo wound contraction study results revealed that diabetic wounds treated with GA-CSNPs nanocomposite scaffold show a faster rate of wound closure (p < .001), histopathology results showed accelerated fibroblast cell migration, reduction of the inflammatory cells, enhanced collagen along with hexosamine synthesis. In addition, immunohistochemistry results showed increased vascularization, a significant decrease in macrophage recruitment, and reduced expression of MMP-9 compared to the Col-fibrin scaffold and Control groups. Overall data suggest that the fabricated GA-CSNPs nanocomposite porous 3-D scaffold can be a hopeful therapeutic choice for diabetic wound management.

A meta‐analysis examined the effect of oxidised regenerated cellulose/collagen dressing on the management of chronic skin wounds

To assess the impact of oxidised regenerated cellulose/collagen dressing on the management of chronic skin wounds, we conducted a meta-analysis. A thorough review of the literature up to September 2022 revealed that 1521 participants had chronic skin wounds at the start of the investigations; 763 of them used oxidised regenerated cellulose/collagen dressing, while 758 received control. Using dichotomous or contentious methods and a random or fixed-effect model, odds ratios (OR) and mean difference (MD) with 95% confidence intervals (CIs) were estimated to evaluate the impact of oxidised regenerated cellulose/collagen dressing on the management of chronic skin wounds. The oxidised regenerated cellulose/collagen dressing had significantly higher complete wound healing (OR, 1.74; 95% CI, 1.06-2.85; P = .03), higher wound relative reduction percent (MD, 13.50; 95% CI, 2.39-24.61; P = .02), and lower adverse events in wound healing (OR, 0.63; 95% CI, 0.41-0.98; P = .04) compared with control in chronic skin wounds. The oxidised regenerated cellulose/collagen dressing had significantly higher complete wound healing, higher wound relative reduction percent and lower adverse events in wound healing compared with control in chronic skin wounds. The low sample size of 8 out of 10 researches in the meta-analysis and the small number of studies in several comparisons calls for care when analysing the results.

A Functionalized Membrane Layer as Part of a Dressing to Aid Wound Healing

PURPOSE

This study is an approach to a dressing platform based on support functionalized with oxygenating factors within an alginate layer, constituting a safe and even contact surface for interface with a wound.

METHODS

An alginate layer with incorporated oxygenating elements deposited on the support patch was assessed. As an oxygenating factor, perfluorooctyl was applied, and the layer coatings in two options, cross-linked and not, were evaluated. The function of human dermal fibroblast cells cultured in the presence of these constructs was analyzed, as well as their morphology using flow cytometry, fluorescence microscopy, and scanning electron microscopy. In addition, the membrane coating material was assessed using FTIR, AFM, and SEM-EDX characterization.

RESULTS

The applied membrane coatings adsorbed on the patch ensured the viability of the human fibroblasts cultured on the membranes during 10 days of culture. However, on the sixth day of culture, the percentage of live cells grown in the presence of cross-linked alginate with oxygenating factor ((ALG-PFC)net) was significantly higher than that of the cells cultured in the presence of the alginate coatings alone. SEM-EDX analysis of the (ALG-PFC)_net confirmed the presence of oxygenating and cross-linking factors. In addition, the regular granular branched structure of the layer coating material involving the oxygenating and cross-linking factors was observed using the AFM technique.

CONCLUSION

The topography of the layer coating material involving the oxygenating and cross-linking factors ensures an even contact surface for interface with the wound. Considering 5-day intervals between dressing replacements, the platform with an oxygenating configuration ensuring the growth and morphology of the human fibroblasts can be recommended at this time as an element of a dressing system.

Porcine Small Intestinal Submucosa Alters the Biochemical Properties of Wound Healing: A Narrative Review

Among the many biological scaffold materials currently available for clinical use, the small intestinal submucosa (SIS) is an effective material for wound healing. SIS contains numerous active forms of extracellular matrix that support angiogenesis, cell migration, and proliferation, providing growth factors involved in signaling for tissue formation and assisting wound healing. SIS not only serves as a bioscaffold for cell migration and differentiation, but also restores the impaired dynamic reciprocity between cells and the extracellular matrix, ultimately driving wound healing. Here, we review the evidence on how SIS can shift the biochemical balance in a wound from chronic to an acute state.

The clinical efficacy of collagen dressing on chronic wounds: A meta-analysis of 11 randomized controlled trials

Objective

This study aims to evaluate the clinical efficacy of collagen dressing for patients with chronic wounds.

Materials and methods

Relevant randomized controlled trials were searched from the databases such as PubMed, EMBASE, and the Cochrane library as of January 2022. For dichotomous outcomes and continuous outcomes, risk ratio and mean difference were calculated, respectively. Subgroup analysis was performed according to the type of chronic ulcer and follow-up. In addition, trial sequential analysis (TSA) was performed to further verify the results. Jadad score was used to assess the quality of trials. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was utilized to assess the level of evidence for outcomes.

Results

In 11 studies, a total of 961 patients of whom 485 were in the collagen group. Compared with standard of care (SOC) alone, the group that added an extra collagen dressing achieved a higher wound healing rate (Risk Ratio = 1.53; 95% CI, 1.33–1.77). The collagen group also showed a higher healing velocity than the SOC group (Mean Difference, 2.69; 95% CI, 0.87–4.51). In addition, the adverse events related to dressing between the two groups were similar (Risk Ratio = 0.67; 95% CI, 0.44–1.01).

Conclusion

Collagen dressing increases the wound healing rate and may be an effective and safe treatment for chronic wound management. However, more extensive research shall be conducted to substantiate these results.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=245728, identifier: CRD42021245728.

Acceleration of Healing in Full-Thickness Wound by Chitosan-Binding bFGF and Antimicrobial Peptide Modification Chitosan Membrane

Skin wound healing is an important clinical challenge, and the main treatment points are accelerating epidermal regeneration and preventing infection. Therefore, it is necessary to develop a wound dressing that can simultaneously cure bacterial infections and accelerate wound healing. Here, we report a multifunctional composite wound dressing loaded with chitosan (CS)-binding bFGF (CSBD-bFGF) and antimicrobial peptides (P5S9K). First, CS was used as the dressing matrix material, and P5S9K was encapsulated in CS. Then, CSBD-bFGF was designed by combining recombinant DNA technology and tyrosinase treatment and modified on the dressing material surface. The results show that the binding ability of CSBD-bFGF and CS was significantly improved compared with that of commercial bFGF, and CSBD-bFGF could be controllably released from the CS dressing. More importantly, the prepared dressing material showed excellent antibacterial activity in vivo and in vitro and could effectively inhibit the growth of E. coli and S. aureus. Using NIH3T3 cells as cellular models, the results showed that the CSBD-bFGF@CS/P5S9K composite dressing was a friendly material for cell growth. After cells were seeded on the composite dressing surface, collagen-1 (COL-1) and vascular endothelial growth factor (VEGF) genes expression in cells were significantly upregulated. Finally, the full-thickness wound of the rat dorsal model was applied to analyse the tissue repair ability of the composite dressing. The results showed that the composite dressing containing CSBD-bFGF and P5S9K had the strongest ability to repair skin wounds. Therefore, the CSBD-bFGF@CS/P5S9K composite dressing has good antibacterial and accelerated wound healing abilities and has good application prospects in the treatment of skin wounds.

Wound Healing Modulation through the Local Application of Powder Collagen-Derived Treatments in an Excisional Cutaneous Murine Model

Wound healing includes dynamic processes grouped into three overlapping phases: inflammatory, proliferative, and maturation/remodeling. Collagen is a critical component of a healing wound and, due to its properties, is of great interest in regenerative medicine. This preclinical study was designed to compare the effects of a new collagen-based hydrolysate powder on wound repair to a commercial non-hydrolysate product, in a murine model of cutaneous healing. Circular excisional defects were created on the dorsal skin of Wistar rats (n = 36). Three study groups were established according to the treatment administered. Animals were euthanized after 7 and 18 days. Morphometric and morphological studies were performed to evaluate the healing process. The new collagen treatment led to the smallest open wound area throughout most of the study. After seven days, wound morphometry, contraction, and epithelialization were similar in all groups. Treated animals showed reduced granulation tissue formation and fewer inflammatory cells, and induction of vasculature with respect to untreated animals. After 18 days, animals treated with the new collagen treatment showed accelerated wound closure, significantly increased epithelialization, and more organized repair tissue. Our findings suggest that the new collagen treatment, compared to the untreated control group, produces significantly faster wound closure and, at the same time, promotes a slight progression of the reparative process compared with the rest of the groups.

Composite Fish Collagen-Hyaluronate Based Lyophilized Scaffolds Modified with Sodium Alginate for Potential Treatment of Chronic Wounds

Chronic wounds are characterized by both decreased collagen deposition and increased collagen breakdown. It is reasonable to hypothesize that exogenous collagen can potentially promote wound healing by reducing degradation enzymes in the wound environment and disrupting the cycle of chronicity. Therefore, this study aimed to develop an optimal combination of fish collagen (FCOL), sodium alginate (SA), and hyaluronic acid (HA) loaded with bovine serum albumin (BSA) as a model protein fabricated as lyophilized scaffolds. The effects of sodium alginate (SA#) with higher mannuronic acid (M) were compared to sodium alginate (SA*) with higher guluronic acid (G). The SA* with higher G resulted in elegant scaffolds with hardness ranging from 3.74 N−4.29 N that were able to withstand the external force due to the glycosidic bonds in guluronic acid. Furthermore, the high G content also had a significant effect on the pore size, pore shape, and porosity. The water absorption (WA) ranged from 380−1382 (%) and equilibrium water content (EWC) 79−94 (%) after 24 h incubation at 37 °C. The SA* did not affect the water vapor transmission rate (WVTR) but incorporating BSA significantly increased the WVTR making these wound dressing scaffolds capable of absorbing about 50% exudate from a heavily exuding chronic wound. The protein released from the composite systems was best explained by the Korsmeyer−Peppas model with regression R2 values ranging from 0.896 to 0.971 and slope or n < 0.5 indicating that the BSA release mechanism was governed by quasi-Fickian diffusion. Cell viability assay showed that the scaffolds did not inhibit the proliferation of human dermal fibroblasts and human epidermal keratinocytes, and are therefore biocompatible. In vitro blood analysis using human whole blood confirmed that the BSA-loaded SA*:FCOL:HA scaffolds reduced the blood clotting index (BCI) by up to 20% compared to a commercially available sponge for chronic wounds. These features confirm that SA*:FCOL:HA scaffolds could be applied as a multifunctional wound dressing.

Formulation and Evaluation of Novel Film Wound Dressing Based on Collagen/Microfibrillated Carboxymethylcellulose Blend

Collagen is essential as a physiological material in wound healing, so it is often used in wound management, mainly as a lyophilisate. Collagen also has excellent film-forming properties; unfortunately, however, its utilisation as a film wound dressing is limited because of its weak mechanical properties, especially in its wet state. For this reason, modifications or combinations with different materials are investigated. The combination of collagen with partially modified microfibrillar carboxymethylcellulose (CMC), which has not previously been described, provided a new possibility for strengthening collagen films and was the aim of this work. The collagen–CMC films based on three types of collagens, two plasticizers and two collagen. Plasticiser ratios were prepared using the solvent casting method; partially modified CMC served here as both a film-forming agent and a filler, without compromising the transparency of the films. The presence of microfibrils was confirmed microscopically by SEM. Organoleptic and physicochemical evaluation, especially in terms of practical application on wounds, demonstrated that all the samples had satisfactory properties for this purpose even after wetting. All the films retained acidic pH values even after 24 h, with a maximum of 6.27 ± 0.17, and showed a mild degree of swelling, with a maximum of about 6 after 24 h.

Composite Membrane Dressings System with Metallic Nanoparticles as an Antibacterial Factor in Wound Healing

Wound management is the burning problem of modern medicine, significantly burdening developed countries’ healthcare systems. In recent years, it has become clear that the achievements of nanotechnology have introduced a new quality in wound healing. The application of nanomaterials in wound dressing significantly improves their properties and promotes the healing of injuries. Therefore, this review paper presents the subjectively selected nanomaterials used in wound dressings, including the metallic nanoparticles (NPs), and refers to the aspects of their application as antimicrobial factors. The literature review was supplemented with the results of our team’s research on the elements of multifunctional new-generation dressings containing nanoparticles. The wound healing multiple molecular pathways, mediating cell types, and affecting agents are discussed herein. Moreover, the categorization of wound dressings is presented. Additionally, some materials and membrane constructs applied in wound dressings are described. Finally, bacterial participation in wound healing and the mechanism of the antibacterial function of nanoparticles are considered. Membranes involving NPs as the bacteriostatic factors for improving wound healing of skin and bones, including our experimental findings, are discussed in the paper. In addition, some studies of our team concerning the selected bacterial strains’ interaction with material involving different metallic NPs, such as AuNPs, AgNPs, Fe₃O₄NPs, and CuNPs, are presented. Furthermore, nanoparticles’ influence on selected eukaryotic cells is mentioned. The ideal, universal wound dressing still has not been obtained; thus, a new generation of products have been developed, represented by the nanocomposite materials with antibacterial, anti-inflammatory properties that can influence the wound-healing process.

Protein-Based Systems for Topical Antibacterial Therapy

Recently, proteins are gaining attention as potential materials for antibacterial therapy. Proteins possess beneficial properties such as biocompatibility, biodegradability, low immunogenic response, ability to control drug release, and can act as protein-mimics in wound healing. Different plant- and animal-derived proteins can be developed into formulations (films, hydrogels, scaffolds, mats) for topical antibacterial therapy. The application areas for topical antibacterial therapy can be wide including bacterial infections in the skin (e.g., acne, wounds), eyelids, mouth, lips, etc. One of the major challenges of the healthcare system is chronic wound infections. Conventional treatment strategies for topical antibacterial therapy of infected wounds are inadequate, and the development of newer and optimized formulations is warranted. Therefore, this review focuses on recent advances in protein-based systems for topical antibacterial therapy in infected wounds. The opportunities and challenges of such protein-based systems along with their future prospects are discussed.

Recent Advances in Nanozymes for Bacteria-Infected Wound Therapy

Bacterial-infected wounds are a serious threat to public health. Bacterial invasion can easily delay the wound healing process and even cause more serious damage. Therefore, effective new methods or drugs are needed to treat wounds. Nanozyme is an artificial enzyme that mimics the activity of a natural enzyme, and a substitute for natural enzymes by mimicking the coordination environment of the catalytic site. Due to the numerous excellent properties of nanozymes, the generation of drug-resistant bacteria can be avoided while treating bacterial infection wounds by catalyzing the sterilization mechanism of generating reactive oxygen species (ROS). Notably, there are still some defects in the nanozyme antibacterial agents, and the design direction is to realize the multifunctionalization and intelligence of a single system. In this review, we first discuss the pathophysiology of bacteria infected wound healing, the formation of bacterial infection wounds, and the strategies for treating bacterially infected wounds. In addition, the antibacterial advantages and mechanism of nanozymes for bacteria-infected wounds are also described. Importantly, a series of nanomaterials based on nanozyme synthesis for the treatment of infected wounds are emphasized. Finally, the challenges and prospects of nanozymes for treating bacterial infection wounds are proposed for future research in this field.

HATMSC Secreted Factors in the Hydrogel as a Potential Treatment for Chronic Wounds-In Vitro Study

Mesenchymal stem cells (MSCs) can improve chronic wound healing; however, recent studies suggest that the therapeutic effect of MSCs is mediated mainly through the growth factors and cytokines secreted by these cells, referred to as the MSC secretome. To overcome difficulties related to the translation of cell therapy into clinical use such as efficacy, safety and cost, we propose a hydrogel loaded with a secretome from the recently established human adipose tissue mesenchymal stem cell line (HATMSC2) as a potential treatment for chronic wounds. Biocompatibility and biological activity of hydrogel-released HATMSC2 supernatant were investigated in vitro by assessing the proliferation and metabolic activity of human fibroblast, endothelial cells and keratinocytes. Hydrogel degradation was measured using hydroxyproline assay while protein released from the hydrogel was assessed by interleukin-8 (IL-8) and macrophage chemoattractant protein-1 (MCP-1) ELISAs. Pro-angiogenic activity of the developed treatment was assessed by tube formation assay while the presence of pro-angiogenic miRNAs in the HATMSC2 supernatant was investigated using real-time RT-PCR. The results demonstrated that the therapeutic effect of the HATMSC2-produced factors is maintained following incorporation into collagen hydrogel as confirmed by increased proliferation of skin-origin cells and improved angiogenic properties of endothelial cells. In addition, HATMSC2 supernatant revealed antimicrobial activity, and which therefore, in combination with the hydrogel has a potential to be used as advanced wound-healing dressing.

A Review of the Effects of Collagen Treatment in Clinical Studies

Collagen, an abundant extracellular matrix protein, has been found to have a lot of pharmaceuticals, medicine, food, and cosmetics applications. Increased knowledge of collagen sources, extraction techniques, structure, and properties in the last decades has helped develop more collagen-based products and tissue engineering biomaterials. Collagen products have been playing an important role in benefiting the health of the human body, especially for aging people. In this paper, the effects of collagen treatment in different clinical studies including skin regeneration, bone defects, sarcopenia, wound healing, dental therapy, gastroesophageal reflux, osteoarthritis, and rheumatoid arthritis have been reviewed. The collagen treatments were significant in these clinical studies. In addition, the associations between these diseases were discussed. The comorbidity of these diseases might be closely related to collagen deficiency, and collagen treatment might be a good choice when a patient has more than one of these diseases, including the coronavirus disease 2019 (COVID-19). It concludes that collagen-based medication is useful in treating comorbid diseases and preventing complications.

Airway Fibroblast Secretory Products Enhance Cell Migration

Background:

The nasal fibroblast secretome, which includes various cytokines, chemokines, and growth factors, promotes cell migration. Currently, the proteomics of airway fibroblast (AF) conditioned medium (AFCM) are being actively studied.

Objective:

This study was aimed at profiling and identifying the AF secreted proteins that can enhance wound healing of the airway epithelium and predict the potential pathway involved.

Methods:

Airway epithelial cells (AECs) and AFs were isolated from redundant human nasal turbinate and cultured. AFCM was collected by culturing the AFs either with serum-free airway epithelium basal medium (AECM) or with serum-free F12:DMEM (FDCM). For evaluating cell migration, the AECs were supplemented with airway epithelium medium and defined keratinocyte medium (1:1; AEDK; control), or with AEDK supplemented with 20% AECM or 20% FDCM. The mass spectrometry sample was prepared by protein precipitation, followed by gel electrophoresis and in-gel digestion.

Results :

AECM promoted better cell migration compared to the FDCM and the control medium. Bioinformatics analysis identified a total of 121, and 92 proteins from AECM and FDCM, respectively: 109 and 82 were identified as secreted proteins, respectively. STRING® analysis predicted that 23 proteins from the AECM and 16 proteins from the FDCM are involved in wound healing.

Conclusion:

Conditioned medium promotes wound healing by enhancing cell migration, and we successfully identified various secretory proteins in a conditioned medium that play important roles in wound healing.

The Protective Effect of Snail Secretion Filtrate in an Experimental Model of Excisional Wounds in Mice

Wound healing is a physiological process comprising several coordinated phases, such as inflammation, proliferation, and remodeling. For centuries, Helix aspersa Muller mucus has been known to have biological properties that are useful for treating skin disorders. In this study, we used a full-thickness excisional wound model in mice to test the hypothesis that Snail Secretion Filtrate (SSF) can improve the wound healing process. The mucus from Helix aspersa Muller was obtained mechanically by manually stimulating snails with a sterile cotton swab tip, and then the mucus was subjected to a series of filtrations to obtain SSF. After wounding, the mice were treated topically with SSF for 14 days. Our macroscopic results show that the SSF treatment significantly improved the speed and percentage of wound area closure. Furthermore, SSF improved several markers of proper wound healing, such as collagen deposition (Masson, COL3A1, matrix metalloproteinases (MMPs)) and the tissue remodeling process (α-sma, vascular-endothelial growth factor (VEGF)). SSF was also able to counteract the inflammatory process in injured wound tissue (myeloperoxidase (MPO) IL-1β, IL-6, TNF-α). In conclusion, our results show that SSF is able to enhance the speed and efficiency of wound healing and positively regulate several aspects of the wound healing process, such as the proliferative and remodeling phases.

Retrospective real-world comparative effectiveness of ovine forestomach matrix and collagen/ORC in the treatment of diabetic foot ulcers

The retrospective pragmatic real‐world data (RWD) study compared the healing outcomes of diabetic foot ulcers (DFUs) treated with either ovine forestomach matrix (OFM) (n = 1150) or collagen/oxidised regenerated cellulose (ORC) (n = 1072) in out‐patient wound care centres. Median time to wound closure was significantly (P = .0015) faster in the OFM group (14.6 ± 0.5 weeks) relative to the collagen/ORC group (16.4 ± 0.7). A sub‐group analysis was performed to understand the relative efficacy in DFUs requiring longer periods of treatment and showed that DFUs treated with OFM healed up to 5.3 weeks faster in these challenging wounds. The percentage of wounds closed at 36 weeks was significantly improved in OFM treated DFUs relative to the collagen/ORC. A Cox proportional hazards analysis showed OFM‐treated wounds had a 18% greater probability of healing versus wounds managed with collagen/ORC, and the probability increased to 21% when the analysis was adjusted for multiple variables. This study represents the first large retrospective RWD analysis comparing OFM and collagen/ORC and supports the clinical efficacy of OFM in the treatment of DFUs.

Efficacy of Oxidized Regenerated Cellulose/Collagen Dressing for Management of Skin Wounds: A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of this study was to evaluate the wound healing efficacy of oxidized regenerated cellulose (ORC)/collagen dressing and ORC/collagen/silver-ORC dressings compared to standard of care or control in treatment of chronic skin wounds such as diabetic foot ulcers (DFUs), venous leg ulcers (VLUs), and pressure injuries sore ulcers (PISUs).

METHODS

An electronic search was carried out in four popular databases PubMed, Scopus, Embase, and CENTRAL to identify thirteen included studies, comparing the clinical efficacy of ORC/collagen dressings when compared to control in management of chronic skin wounds, especially DFUs, VLUs, and PISUs, and skin graft donor site wounds.

RESULTS

Consolidated data from thirteen comparative clinical studies undertaken for management of DFUs, VLUs, and PISUs showed favorable outcomes towards use of ORC/collagen compared to other traditional and hydrocolloid foam dressings in terms of wound healing rate (P=0.02) and percentage wound relative reduction (P=0.003). The time taken to achieve complete wound healing in the included studies did not show any statistical significant difference (P=0.24). There was no significant difference in adverse events between ORC/collagen-treated group and comparative group (P=0.19).

CONCLUSION

ORC/collagen wound dressings are beneficial in terms of improved wound healing rate and percentage wound relative reduction compared to already existing traditional standard of care with non-MMP, inhibiting biomaterials such as moistened gauze, autologous growth factors, hydrocolloid foam dressings, or ovine extracellular matrix.

Type I collagen hydrogels as a delivery matrix for royal jelly derived extracellular vesicles

Throughout the last decade, extracellular vesicles (EVs) have become increasingly popular in several areas of regenerative medicine. Recently, Apis mellifera royal jelly EVs (RJ EVs) were shown to display favorable wound healing properties such as stimulation of mesenchymal stem cell migration and inhibition of staphylococcal biofilms. However, the sustained and effective local delivery of EVs in non-systemic approaches – such as patches for chronic cutaneous wounds – remains an important challenge for the development of novel EV-based wound healing therapies. Therefore, the present study aimed to assess the suitability of type I collagen -a well-established biomaterial for wound healing – as a continuous delivery matrix. RJ EVs were integrated into collagen gels at different concentrations, where gels containing 2 mg/ml collagen were found to display the most stable release kinetics. Functionality of released RJ EVs was confirmed by assessing fibroblast EV uptake and migration in a wound healing assay. We could demonstrate reliable EV uptake into fibroblasts with a sustained pro-migratory effect for up to 7 d. Integrating fibroblasts into the RJ EV-containing collagen gel increased the contractile capacity of these cells, confirming availability of RJ EVs to fibroblasts within the collagen gel. Furthermore, EVs released from collagen gels were found to inhibit Staphylococcus aureus ATCC 29213 biofilm formation. Overall, our results suggest that type I collagen could be utilized as a reliable, reproducible release system to deliver functional RJ EVs for wound healing therapies.

Application of Fish Collagen-Nanochitosan-Henna Extract Composites for the Control of Skin Pathogens and Accelerating Wound Healing

Skin is the largest protective organ that could be recurrently wounded and attacked by microorganisms. The wounded skin safeguarding and supporting were intended through natural derivatives. Fish collagen (Cg) type I, extracted from sea bream (Spondyliosoma cantharus), chitosan nanoparticles (NCht) from shrimp shells, and henna (Lawsonia inermis L.) leaves extract (He) were produced and physiochemically characterized. The antimicrobial potentialities of these compounds and their composites were assessed toward skin pathogens (Candida albicans and Staphylococcus aureus) using various assaying methods and microimaging techniques. The infrared and electrophoretic analysis of Cg validated its characteristics, and the IR-spectroscopic analysis of the compounds/composites indicated their physiochemical attributes and interrelations. The produced NCht particles had a diameter range of 64.6-308.8 nm, 104 nm mean diameter, and +31.3 mV zeta potentiality. Both NCht, He, and NCht/He composite exhibited significant antimicrobial potentiality toward skin pathogens; NCht/He was the strongest with inhibitory concentrations of 20.0 and 22.5 μg/mL and inhibition zones of 25.7 and 26.8 mm against S. aureus and C. albicans, respectively. The electron micrographs verified the synergistic microbicidal action of NCht/He, as they led to severe microbial lysis and deformations. The skin wounds’ treatment with NCht/He/Cg composite promoted the fastest and complete healing of wounded rats’ skin during 8 days of local treatment, with the absence of inflammation and infection signs; treated with NCht/He/Cg composite, the wound area vastly reduced from 63.6 mm2 to 15.9 and 9.1 mm2 after 2 and 4 days, respectively. The natural NCht/He/Cg composites are recommended as topical applications for optimum skin disinfection and regeneration.

Bioactives from Bee Products and Accompanying Extracellular Vesicles as Novel Bioactive Components for Wound Healing

In recent years, interest has surged among researchers to determine compounds from bee products such as honey, royal jelly, propolis and bee pollen, which are beneficial to human health. Mass spectrometry techniques have shown that bee products contain a number of proven health-promoting compounds but also revealed rather high diversity in the chemical composition of bee products depending on several factors, such as for example botanical sources and geographical origin. In the present paper, we present recent scientific advances in the field of major bioactive compounds from bee products and corresponding regenerative properties. We also discuss extracellular vesicles from bee products as a potential novel bioactive nutraceutical component. Extracellular vesicles are cell-derived membranous structures that show promising potential in various therapeutic areas. It has been extensively reported that the use of vesicles, which are naturally formed in plant and animal cells, as delivery agents have many advantages. Whether the use of extracellular vesicles from bee products represents a new solution for wound healing remains still to be elucidated. However, promising results in specific applications of the bee products in wound healing and tissue regenerative properties of extracellular vesicles provide a good rationale to further explore this idea.

Use of an advanced collagen matrix dressing on patients with complex chronic lower extremity ulcers: A case series

The objective of this case series was to assess the wound healing effectiveness of a collagen matrix wound dressing containing partially denatured collagen, carboxymethyl cellulose, alginate and ethylenediaminetetraacetic acid in chronic lower extremity ulcers. A total of nine patients with refractory lower extremity ulcers were treated with the collagen contact layer in addition to standard of care. Wound healing progress was measured at 2, 4 and 8 weeks. An average decrease in wound size of 73% was achieved across patients at week 8, with complete healing in two patients. The intervention was easy to use and well tolerated by patients. The results of this study, although preliminary, suggest that the advanced collagen matrix dressing represents an effective and safe treatment strategy for healing refractory chronic lower extremity ulcers of varying etiologies. Further investigation is needed to evaluate efficacy in a larger randomized clinical trial with focus on cost-effectiveness and impact on patient’s quality-of-life.

Review of the Applications of Biomedical Compositions Containing Hydroxyapatite and Collagen Modified by Bioactive Components

Regenerative medicine is becoming a rapidly evolving technique in today’s biomedical progress scenario. Scientists around the world suggest the use of naturally synthesized biomaterials to repair and heal damaged cells. Hydroxyapatite (HAp) has the potential to replace drugs in biomedical engineering and regenerative drugs. HAp is easily biodegradable, biocompatible, and correlated with macromolecules, which facilitates their incorporation into inorganic materials. This review article provides extensive knowledge on HAp and collagen-containing compositions modified with drugs, bioactive components, metals, and selected nanoparticles. Such compositions consisting of HAp and collagen modified with various additives are used in a variety of biomedical applications such as bone tissue engineering, vascular transplantation, cartilage, and other implantable biomedical devices.

Emerging Role of Hydrogels in Drug Delivery Systems, Tissue Engineering and Wound Management

The popularity of hydrogels as biomaterials lies in their tunable physical properties, ability to encapsulate small molecules and macromolecular drugs, water holding capacity, flexibility, and controllable degradability. Functionalization strategies to overcome the deficiencies of conventional hydrogels and expand the role of advanced hydrogels such as DNA hydrogels are extensively discussed in this review. Different types of cross-linking techniques, materials utilized, procedures, advantages, and disadvantages covering hydrogels are tabulated. The application of hydrogels, particularly in buccal, oral, vaginal, and transdermal drug delivery systems, are described. The review also focuses on composite hydrogels with enhanced properties that are being developed to meet the diverse demand of wound dressing materials. The unique advantages of hydrogel nanoparticles in targeted and intracellular delivery of various therapeutic agents are explained. Furthermore, different types of hydrogel-based materials utilized for tissue engineering applications and fabrication of contact lens are discussed. The article also provides an overview of selected examples of commercial products launched particularly in the area of oral and ocular drug delivery systems and wound dressing materials. Hydrogels can be prepared with a wide variety of properties, achieving biostable, bioresorbable, and biodegradable polymer matrices, whose mechanical properties and degree of swelling are tailored with a specific application. These unique features give them a promising future in the fields of drug delivery systems and applied biomedicine.

Recent advances on polymeric hydrogels as wound dressings

Severe hemorrhage is a leading cause of high mortality in critical situations like disaster, accidents, and warfare. The resulting wounds could induce severe physical and psychological trauma to patients and also bring an immense socio-economic burden. Hence, rapid hemostasis and wound healing techniques have become critical initiatives for life-saving treatment. Although traditional methods relying on bandages and gauzes are effective in controlling hemorrhage, they suffer from several limitations: nonbiodegradability, being susceptible to infection, being unsuitable for the irregular wound, secondary tissue damage, and being almost ineffective for wound healing. Owing to the merits of high porosity, good biocompatibility, tunable physicochemical properties, and being beneficial for wound healing, hydrogels with excellent performance have drawn intensive attention and numerous novel effective hydrogel dressings have been widely developed. In this Review, after introducing some commonly used strategies for the synthesis of hydrogels, the most recent progress on polymer-based hydrogels as wound dressings is discussed. Particularly, their hemostasis, antibacterial, and biodegradation properties are introduced. Finally, challenges and future perspectives about the development of hydrogels for wound dressings are outlined.

Modulating the Biomechanical Properties of Engineered Connective Tissues by Chitosan-Coated Multiwall Carbon Nanotubes

Background

Under certain conditions, the physiological repair of connective tissues might fail to restore the original structure and function. Optimized engineered connective tissues (ECTs) with biophysical properties adapted to the target tissue could be used as a substitution therapy. This study aimed to investigate the effect of ECT enforcement by a complex of multiwall carbon nanotubes with chitosan (C-MWCNT) to meet in vivo demands.

Materials and Methods

ECTs were constructed from human foreskin fibroblasts (HFF-1) in collagen type I and enriched with the three different percentages 0.025, 0.05 and 0.1% of C-MWCNT. Characterization of the physical properties was performed by biomechanical studies using unidirectional strain.

Results

Supplementation with 0.025% C-MWCNT moderately increased the tissue stiffness, reflected by Young’s modulus, compared to tissues without C-MWCNT. Supplementation of ECTs with 0.1% C-MWCNT reduced tissue contraction and increased the elasticity and the extensibility, reflected by the yield point and ultimate strain, respectively. Consequently, the ECTs with 0.1% C-MWCNT showed a higher resilience and toughness as control tissues. Fluorescence tissue imaging demonstrated the longitudinal alignment of all cells independent of the condition.

Conclusion

Supplementation with C-MWCNT can enhance the biophysical properties of ECTs, which could be advantageous for applications in connective tissue repair.

One Step e-Beam Radiation Cross-Linking of Quaternary Hydrogels Dressings Based on Chitosan-Poly(Vinyl-Pyrrolidone)-Poly(Ethylene Glycol)-Poly(Acrylic Acid)

We report on the successful preparation of wet dressings hydrogels based on Chitosan-Poly(N-Vinyl-Pyrrolidone)-Poly(ethylene glycol)-Poly(acrylic acid) and Poly(ethylene oxide) by e-beam cross-linking in weakly acidic media, to be used for rapid healing and pain release of infected skin wounds. The structure and compositions of hydrogels investigated according to sol-gel and swelling studies, network parameters, as well as FTIR and XPS analyses showed the efficient interaction of the hydrogel components upon irradiation, maintaining the bonding environment while the cross-linking degree increasing with the irradiation dose and the formation of a structure with the mesh size in the range 11–67 nm. Hydrogels with gel fraction above 85% and the best swelling properties in different pH solutions were obtained for hydrogels produced with 15 kGy. The hydrogels are stable in the simulated physiological condition of an infected wound and show appropriate moisture retention capability and the water vapor transmission rate up to 272.67 g m⁻² day⁻¹, to ensure fast healing. The hydrogels proved to have a significant loading capacity of ibuprofen (IBU), being able to incorporate a therapeutic dose for the treatment of severe pains. Simultaneously, IBU was released up to 25% in the first 2h, having a release maximum after 8 h.

The effect of Smad2- and Smad3-targeting RNA interference on extracellular matrix synthesis in rat fibroblasts of peritoneal adhesion tissues

Fibroblasts migrating to peritoneum injuries play an important role in the development of postoperative peritoneal adhesions due to the excessive synthesis and deposition of extracellular matrix (ECM). This effect is mainly induced by the transforming growth factor-β (TGF-β). Studies indicate that elevated TGF-β1 levels and TGF-β1/Smad signaling are both implicated in the formation of peritoneal adhesions. To confirm the effect of TGF-β1/Smad signaling interference in regulating excessive ECM synthesis, a total of four different R-Smad-targeting small interference RNA (siRNA) duplexes (Smad2-500, Smad2-956, Smad3-378, Smad3-1385) were tested in this study using a TGF-β1-stimulated adhesion tissue fibroblasts (ATFs) cell model. The in vitro assessments show that all proposed siRNAs are capable of significantly downregulating the mRNA and protein levels of Smad2 and Smad3 in ATFs. They also inhibit the phosphorylation of both Smads, which confirms their effect in blocking the TGF-β1/Smad signaling pathway. Moreover, the siRNA duplexes can appreciably lower the elevated levels of fibronectin and collagen 3 alpha 1 (COL3A1) in TGF-β1-stimulated ATFs, and the Smad3-378 siRNA can actually restore both molecules (fibronectin and COL3A1) to normal levels. Therefore, the Smad3-378 siRNA is suitable for both adhesion prevention and wound healing. Overall, our results indicate that postoperative adhesion prophylaxis may be achieved by temporarily blocking TGF-β1/Smad signaling transduction.

Recent trends on wound management: New therapeutic choices based on polymeric carriers

Wound healing is an unmet therapeutic challenge among medical society since wound assessment and management is a complex procedure including several factors playing major role in healing process. Wounds can mainly be categorized as acute or chronic. It is well referred that the acute wound displays normal wound physiology while healing, in most cases, is seemed to progress through the normal phases of wound healing. On the other hand, a chronic wound is physiologically impaired. The main problem in wound management is that the majority of wounds are colonized with microbes, whereas this does not mean that all wounds will be infected. In this review, we address the problems that clinicians face to manage while treat acute and chronic wounds. Moreover, we demonstrate the pathophysiology, etiology, prognosis and microbiology of wounds. We further introduce the state of art in pharmaceutical technology field as part of wound management aiming to assist health professionals to overcome the current implications on wound assessment. In addition, authors review researches which included the use of gels and dermal films as wound healing agents. It can be said that natural and synthetic drugs or carriers provide promising solutions in order to meet the wound management standards. However, are the current strategies as desirable as medical society wish?

Regenerative Wound Dressings for Skin Cancer

Skin cancer is considered the most prevalent cancer type globally, with a continuously increasing prevalence and mortality growth rate. Additionally, the high risk of recurrence makes skin cancer treatment among the most expensive of all cancers, with average costs estimated to double within 5 years. Although tumor excision is the most effective approach among the available strategies, surgical interventions could be disfiguring, requiring additional skin grafts for covering the defects. In this context, post-surgery management should involve the application of wound dressings for promoting skin regeneration and preventing tumor recurrence and microbial infections, which still represents a considerable clinical challenge. Therefore, this paper aims to provide an up-to-date overview regarding the current status of regenerative wound dressings for skin cancer therapy. Specifically, the recent discoveries in natural biocompounds as anti-cancer agents for skin cancer treatment and the most intensively studied biomaterials for bioactive wound dressing development will be described.

Marine fish peptides (collagen peptides) compound intake promotes wound healing in rats after cesarean section

Background

Wound complications are a major source of morbidity after cesarean section (CS) and contribute to increased risks in subsequent pregnancies. In the present study, we aim to investigate the wound healing potential of a kind of oligopeptide compound, mainly derived from the marine fish peptides (MFPs), in rats after CS by biomechanical, biochemical, and histological methods.

Methods

Eighty-four pregnant Sprague–Dawleyrats were randomly assigned to four groups, namely the control group and 1.1, 2.2, and 4.4 mg/kg MFP groups, respectively. The MFPs or normal saline of the equal volume was intragastrically administered every morning on the second day after CS. On days 5, 10, and 15 after the surgery, seven rats from each group were randomly selected. The samples of skin wound and uterus were harvested and then used for the following experiments and analyses.

Results

Using the CS rat model, this study demonstrated that in the MFP groups, the skin tensile strength, uterine bursting pressure, and hydroxyproline (Hyp) were significantly higher than those in the control group at all three time points (P < 0.05). The formation of collagen and smooth muscle fibers and the expression of CD34 and connective tissue growth factor at the incision site were increasingly observed in the MFP groups (P < 0.05).

Conclusions

MFPs have a great potential to accelerate the process and quality of wound healing in rats after CS.

Recent Advances in Tissue Adhesives for Clinical Medicine

Tissue adhesives have attracted more attention to the applications of non-invasive wound closure. The purpose of this review article is to summarize the recent progress of developing tissue adhesives, which may inspire researchers to develop more outstanding tissue adhesives. It begins with a brief introduction to the emerging potential use of tissue adhesives in the clinic. Next, several critical mechanisms for adhesion are discussed, including van der Waals forces, capillary forces, hydrogen bonding, static electric forces, and chemical bonds. This article further details the measurement methods of adhesion and highlights the different types of adhesive, including natural or biological, synthetic and semisynthetic, and biomimetic adhesives. Finally, this review article concludes with remarks on the challenges and future directions for design, fabrication, and application of tissue adhesives in the clinic. This review article has promising potential to provide novel creative design principles for the generation of future tissue adhesives.

Design Considerations for Hydrogel Wound Dressings: Strategic and Molecular Advances

Wound dressings are traditionally used to protect a wound and to facilitate healing. Currently, their function is expanding. There is an urgent need for new smart products that not only act as a protective barrier but also actively support the wound healing process. Hydrogel dressings are an example of such innovative products and typically facilitate wound healing by providing a hospitable and moist environment in which cells can thrive, while the wound can still breathe and exudate can be drained. These dressings also tend to be less painful or have a soothing effect and allow for additional drug delivery. In this review, various strategic and molecular design considerations are discussed that are relevant for developing a hydrogel into a wound dressing product. These considerations vary from material choice to ease of use and determine the dressing's final properties, application potential, and benefits for the patient. The focus of this review lies on identifying and explaining key aspects of hydrogel wound dressings and their relevance in the different phases of wound repair. Molecular targets of wound healing are discussed that are relevant when tailoring hydrogels toward specific wound healing scenarios. In addition, the potential of hydrogels is reviewed as medicine advances from a repair-based wound healing approach toward a regenerative-based one. Hydrogels can play a key role in the transition toward personal wound care and facilitating regenerative medicine strategies by acting as a scaffold for (stem) cells and carrier/source of bioactive molecules and/or drugs. Impact statement Improved wound healing will lead to a better quality of life around the globe. It can be expected that this coincides with a reduction in health care spending, as the duration of treatment decreases. To achieve this, new and modern wound care products are desired that both facilitate healing and improve comfort and outcome for the patient. It is proposed that hydrogel wound dressings can play a pivotal role in improving wound care, and to that end, this review aims to summarize the various design considerations that can be made to optimize hydrogels for the purpose of a wound dressing.

Encapsulation of collagen mimetic peptide-tethered vancomycin liposomes in collagen-based scaffolds for infection control in wounds

Wound infections are a significant clinical problem affecting millions of people worldwide. Topically applied antibacterial formulations with longer residence time and controlled antimicrobial release would offer significant benefits for improved prevention and treatment of infected wounds. In this study, we developed collagen mimetic peptide (CMP) tethered vancomycin (Van)-containing liposomes (Lipo) (CMP-Van-Lipo) hybridized to collagen-based hydrogels ('co-gels,' e.g., collagen/fibrin combination hydrogels) for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in vitro and in vivo. Tethering CMP-Van-Lipo nanostructures to co-gels enabled sustained Van release and enhanced in vitro antibacterial effects against MRSA as compared to Van loaded co-gels or Van-Lipo loaded co-gels following multiple fresh bacterial inoculations over a period of 48 h. These results were successfully translated in vivo wherein MRSA infected wounds were effectively treated with CMP-Van-Lipo loaded co-gels for up to 9 days, whereas the activity of Van loaded co-gels and Van-Lipo loaded co-gels were limited to <2 days. Moreover, CMP-Van-Lipo retained in vivo antibacterial activity even after re-inoculation with bacteria; however, Van loaded co-gels and Van-Lipo loaded co-gels allowed significant bacterial growth demonstrating their limited efficacy. Altogether, these results provide proof-of-concept that CMP-Van-Lipo loaded co-gels can be effective topical formulations for preventive treatment of MRSA wound infections. STATEMENT OF SIGNIFICANCE: Current topical antimicrobial formulations (e.g., creams, gels, and ointments) do not control release, leaving antimicrobial concentrations either too high or too low at different time points, and provoking the development of antibacterial resistance and recurrence of wound infections. Here, collagen mimetic peptides (CMPs) were used to stably hybridize vancomycin-containing liposomal nanocarriers (CMP-Van-Lipo) within collagen-fibrin co-gels via triple-helical integration with collagen, enabling control over Van release for prolonged time periods and minimizing the adverse effects of the Lipo formulations on fibroblast cell viability in the wound bed. The CMP-Van-Lipo loaded co-gel's higher antibacterial effects in vitro were successfully translated in vivo for treatment of MRSA-infected mouse wounds, and thus the co-gels can be a potentially translatable treatment for improved clinical wound management.

A comparative study of two porous sponge scaffolds prepared by collagen derived from porcine skin and fish scales as burn wound dressings in a rabbit model

Collagen is widely used in biomedical applications due to its outstanding properties. In this study, highly porous sponge scaffolds were developed by using porcine skin-derived collagen (PSC) and fish scale-derived collagen (FSC), respectively. The morphology and composition of these PSC and FSC scaffolds were compared. The water uptake ratio of FSC scaffolds reached 47.8, which is 1.7 times of PSC scaffolds. The water vapour transmission rates (WVTR) of PSC and FSC scaffolds were 952.6 ± 55.5 and 1090.9 ± 77.1 g/m²/day, which could produce a moist healing environment for wounds. Both scaffolds show non-toxicity to L929 fibroblast cells. The burn wound healing efficiency of these two scaffolds was examined in vivo using rabbits. No scars around the wounds were observed after applying PSC and SFC scaffolds. Histopathological studies reveal that the wound treated with PSC and FSC scaffolds showed much better wound recovery than gauze and vaseline gauze groups. It was suggested that FSC scaffolds have great potential as same as PSC to be used as burn wound dressing materials.

Energetic electron assisted synthesis of highly tunable temperature-responsive collagen/elastin gels for cyclic actuation: macroscopic switching and molecular origins

Thermoresponsive bio-only gels that yield sufficiently large strokes reversibly and without large hysteresis at a well-defined temperature in the physiological range, promise to be of value in biomedical application. Within the present work we demonstrate that electron beam modification of a blend of natural collagen and elastin gels is a route to achieve this goal, viz. to synthesize a bioresorbable gel with largely reversible volume contractions as large as 90% upon traversing a transition temperature that can be preadjusted between 36 °C and 43 °C by the applied electron dose. Employing circular dichroism and temperature depending confocal laser scanning microscopy measurements, we furthermore unravel the mechanisms underlying this macroscopic behavior on a molecular and network level, respectively and suggest a stringent picture to account for the experimental observations.

Biopolymer-based biomaterials for accelerated diabetic wound healing: A critical review

Non-healing, chronic wounds place a huge burden on healthcare systems as well as individual patients. These chronic wounds especially diabetic wounds will ultimately lead to compromised mobility, amputation of limbs and even death. Currently, wounds and limb ulcers associated with diabetes remain significant health issues; the associated healthcare cost ultimately leads to the increased clinical burden. The presence of diabetes interrupts a highly coordinated cascade of events in the wound closure process. Advances in the understanding of pathophysiological conditions associated with diabetic wounds lead to the development of drug delivery systems which can enhance wound healing by targeting various phases of the impaired processes. Wound environments typically contain degradative enzymes, along with an elevated pH and demonstrate a physiological cascade involved in the regeneration of tissue, which requires the application of an effective delivery system. This article aims to review the pathophysiological conditions associated with chronic and diabetic wounds. The delivery systems, involved in their treatment are described, highlighting potential biomaterials and polymers for establishing drug delivery systems, specifically for the treatment of diabetic wounds and the promotion of the associated mechanisms involved in advanced wound healing. Emerging approaches and engineered devices for effective wound care are reported. The discussion will give insight into the mechanisms relevant to all stages of wound healing.

Collagen-Based Tissue Engineering Strategies for Vascular Medicine

Cardiovascular diseases (CVDs) account for the 31% of total death per year, making them the first cause of death in the world. Atherosclerosis is at the root of the most life-threatening CVDs. Vascular bypass/replacement surgery is the primary therapy for patients with atherosclerosis. The use of polymeric grafts for this application is still burdened by high-rate failure, mostly caused by thrombosis and neointima hyperplasia at the implantation site. As a solution for these problems, the fast re-establishment of a functional endothelial cell (EC) layer has been proposed, representing a strategy of crucial importance to reduce these adverse outcomes. Implant modifications using molecules and growth factors with the aim of speeding up the re-endothelialization process has been proposed over the last years. Collagen, by virtue of several favorable properties, has been widely studied for its application in vascular graft enrichment, mainly as a coating for vascular graft luminal surface and as a drug delivery system for the release of pro-endothelialization factors. Collagen coatings provide receptor-ligand binding sites for ECs on the graft surface and, at the same time, act as biological sealants, effectively reducing graft porosity. The development of collagen-based drug delivery systems, in which small-molecule and protein-based drugs are immobilized within a collagen scaffold in order to control their release for biomedical applications, has been widely explored. These systems help in protecting the biological activity of the loaded molecules while slowing their diffusion from collagen scaffolds, providing optimal effects on the targeted vascular cells. Moreover, collagen-based vascular tissue engineering substitutes, despite not showing yet optimal mechanical properties for their use in the therapy, have shown a high potential as physiologically relevant models for the study of cardiovascular therapeutic drugs and diseases. In this review, the current state of the art about the use of collagen-based strategies, mainly as a coating material for the functionalization of vascular graft luminal surface, as a drug delivery system for the release of pro-endothelialization factors, and as physiologically relevant in vitro vascular models, and the future trend in this field of research will be presented and discussed.

Effect of Native Type I Collagen with Polyhexamethylene Biguanide Antimicrobial on Wounds: Interim Registry Results

BACKGROUND

Biofilm can impair wound healing by maintaining an elevated, but ineffective, inflammatory state. This article describes interim results from the prospective RESPOND postmarketing registry evaluating the use of a native type 1, porcine collagen matrix with the embedded antimicrobial polyhexamethylene biguanide (PCMP) in the management of chronic wounds.

METHODS

Adults ≥18 years of age with ≥1 appropriate wound were eligible for inclusion. Data that were final on January 26, 2018 were included in this analysis. At week 0, wounds were cleaned, debrided, and prepared as necessary and PCMP was applied, with a dressing to fix it in place. Patients received standard wound care plus PCMP weekly, up to 24 weeks, at the investigator's discretion. At each visit, wounds were assessed for area and quality of granulation tissue.

RESULTS

Most common wound types (N = 63) were venous ulcers (28.6%), trauma and lacerations (22.2%), postsurgical open wounds (15.9%), pressure injuries (12.7%), and diabetic ulcers (9.5%). Median baseline wound area was 6.5 cm2; mean wound duration at baseline was 4 months. Of the 63 wounds, 43 (68.3%) achieved complete wound closure, 41 of 43 (95.3%) closed after PCMP treatment, and 2 of 43 (4.7%) after bridging to other modalities and surgical closure. Twelve out of 63 wounds were bridged to other modalities after PCMP treatment. Mean time to closure for PCMP wounds was 5.0 weeks.

CONCLUSIONS

PCMP appears to be a useful adjunct for treating various wound types. PCMP use should be considered when managing chronic or acute wounds.