Biological Mechanisms of Chronic Wound and Diabetic Foot Healing: The Role of Collagen

Deep Learning for Cell Migration in Nonwoven Materials and Evaluating Gene Transfer Effects following AAV6-ND4 Transduction

Studying cell settlement in the three-dimensional structure of synthetic biomaterials over time is of great interest in research and clinical translation for the development of artificial tissues and organs. Tracking cells as physical objects improves our understanding of the processes of migration, homing, and cell division during colonisation of the artificial environment. In this study, the 3D environment had a direct effect on the behaviour of biological objects. Recently, deep learning-based algorithms have shown significant benefits for cell segmentation tasks and, furthermore, for biomaterial design optimisation. We analysed the primary LHON fibroblasts in an artificial 3D environment after adeno-associated virus transduction. Application of these tools to model cell homing in biomaterials and to monitor cell morphology, migration and proliferation indirectly demonstrated restoration of the normal cell phenotype after gene manipulation by AAV transduction. Following the 3Rs principles of reducing the use of living organisms in research, modeling the formation of tissues and organs by reconstructing the behaviour of different cell types on artificial materials facilitates drug testing, the study of inherited and inflammatory diseases, and wound healing. These studies on the composition and algorithms for creating biomaterials to model the formation of cell layers were inspired by the principles of biomimicry.

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.

Estimation of the repair efficiency of collagen matrices on the model of thermal burn

Background. In the world, dozens of new local wound healing agents are developed and improved every year, which undergo preliminary tests on laboratory animals due to the presence of common phases of the course of the wound process with humans.

The aim of the study was to evaluate the wound healing effect of matrices obtained on the basis of the recycling of collagen-containing waste.

Materials and methods. Collagen matrices are obtained from substandard leather raw materials subjected to treatment with fermented milk composition (KM1) and lactic acid (KM2). The wound healing effect was studied on the model of thermal burns on Wistar rats in 5 groups: 1st – control (natural wound healing); 2nd – experimental 1 (processing KM1); 3rd – experimental 2 (processing KM2); 4th – experimental 3, comparison group (“Levomekol”) and 5th – intact animals (normal, without burns). Wound healing was assessed by the results of planimetry on days 1, 3, 5, 7, 9, and 13 and by histological analysis of the skin tissue on days 6, 13, and 20. On days 6 and 13, the summary antioxidant activity, the total content of leukocytes, erythrocytes, the activity of the catalase enzyme, and the content of malondialdehyde were determined in the blood of rats.

Results. With thermal damage to the skin, an IIIA degree burn was formed, accompanied by the development of dry coagulation necrosis. The use of collagen matrices restored the total content of leukocytes, reduced the area of the burn wound, normalized the content of malondialdehyde, the total antioxidant activity and the activity of catalase in the blood. Histomorphometric studies have confirmed the dynamics of skin tissue recovery after a burn. The effectiveness of the use of matrices was comparable to the pharmacopoeial drug “Levomekol”. A higher wound healing effect was noted when using the KM1 matrix.

Conclusion. On the model of thermal burn, the wound-healing effect of collagen matrices was established, as evidenced by the results of restoring the number of leukocytes, reducing the area of the burn wound and restoring the histostructure of the skin. One of the molecular and cellular mechanisms of wound healing is the inhibition of lipid peroxidation reactions and the restoration of the antioxidant potential of the body. 

Collagen-based formulations for wound healing: A literature review

Wounds have always been the point of concern owing to the involvement of infections and the level of severity. Therefore, the management of wounds always requires additional effort for comprehensive healing and subsequent removal of the scar from the wound site. The role of biomaterials in the management of chronic wounds has been well established. One of such biomaterials is collagen (Col) that is considered to be the crucial component of most of the formulations being developed for wound healing. The role of Col extracted from marine invertebrates remains an unmarked origin of the proteinaceous constituent in the evolution of innovative pharmaceuticals. Col is a promising, immiscible, fibrous amino acid of indigenous origin that is ubiquitously present in extracellular matrices and connective tissues. There are different types of Col present in the body such as type I, II, III, IV, and V however the natural sources of Col are vegetables and marine animals. Its physical properties like high tensile strength, adherence nature, elasticity, and remodeling contribute significantly in the wound healing process. Col containing formulations such as hydrogels, sponges, creams, peptides, and composite nanofibers have been utilized widely in wound healing and tissue engineering purposes truly as the first line of defense. Here we present the recent advancements in Col based dosage forms for wound healing. The Col based market of topical preparations and the published reports identify Colas a useful biomaterial for the delivery of pharmaceuticals and a platform for tissue engineering.

Acute Skin Wounds Treated with Mesenchymal Stem Cells and Biopolymer Compositions Alone and in Combination: Evaluation of Agent Efficacy and Analysis of Healing Mechanisms

We studied the efficacy of using mesenchymal stem cells (MSC) and a polymeric compound (based on chitosan and cellulose with integrated cerium dioxide nanoparticles (PCCD)) in wound healing, and to compare the effects with various invasive and external drugs used for the same purpose. Two wounds were made on the backs of each of 112 Wistar rats, removing the skin. Eight groups were studied: Control_0—intact wounds; Control_ss—0.9% NaCl injections; MSC injections; Control_msc—intact wounds on the opposite side of the body from the MSC group; external application of the PCCD; external application of a combination of the drugs PCCD + MSC; DCh –ointment Dioxomethyltetrahydropyrimidine + Chloramphenicol; and DHCB—injections of a deproteinized hemoderivative of calf blood. After 14 days, we evaluated the state and size of the wounds, studied the level of microcirculation, performed a histological study, and identified and counted the different types of cells. The most effective remedy was combination PCCD + MSC. The treatments in the PCCD and MSC groups were more effective than in the DHCB and DCh groups. Invasive drugs and DCh slowed the regeneration process. DHCB did not affect the rate of healing for acute wounds without ischemia during the first week. The proven efficacy of developed polymeric compounds demonstrates the feasibility of further studies in clinical practice.

Application of Polymer Drugs with Cerium Dioxide Nanomolecules and Mesenchymal Stem Cells for the Treatment of Skin Wounds in Aged Rats

The urgency of the problem of wound healing is not in doubt, given the global trend of an increase in the number of operations and injuries with skin damage, as well as the lack of universal means of treating wounds.

STUDY OBJECTIVE

To compare the effectiveness of the developed drugs, smart polymeric nano-drug with cerium oxide nanoparticles (SPN), and smart polymeric nano-drug in combination with mesenchymal stem cells (SPN + SC) on the healing process of skin wounds.

MATERIAL AND METHODS

An experimental study was carried out using Wistar rats of post-reproductive age, which had dermis and epidermis removed on their backs. There were four groups of wounds in total: control, treatment with mesenchymal stem cells (SC), SPN, and SPN + SC.

RESULTS

A positive therapeutic effect of polymeric drugs on the dynamics of wound area reduction was established, which was most typical for wounds of the SPN group and, particularly, the SPN + SC group. On the third day, an anti-inflammatory effect was revealed in the SC and the SPN + SC groups in particular, which was expressed in a reduced leukocyte infiltration and an increase in the level of microcirculation during this period. The fastest transition from the phase of exudation to proliferation was recorded in the SPN and SPN + SC groups. Histologically, these groups showed faster regeneration, including the epithelialization of wounds.

CONCLUSION

The results obtained in the course of the study open up possibilities for the development of fundamentally new, highly effective wound healing agents.

Comparative Analysis of the Effectiveness of Some Biological Injected Wound Healing Stimulators and Criteria for Its Evaluation

PURPOSE

To investigate the comparative effectiveness of certain biological injectable stimulants for the healing of skin wounds and criteria for its assessment.

MATERIALS AND METHODS

A comparative study of the effectiveness of mesenchymal stem cells (SC group), collagen (Collagen group), and deproteinized calf blood hemoderivative (DCBH group) was carried out using an acute wound model. Control wounds were injected with isotonic sodium chloride solution (Control group). A total of four groups (28 wounds per group) were included in the study. Aged male Wistar rats were used as experimental animals. A dynamic assessment of the wound areas and edges, microvasculature assessment via laser Doppler flowmetry, histological and morphometric analyses to determine the quantitative and qualitative fibroblasts composition, as well as the degree of newly synthesized collagen maturity, was conducted on days 0, 3, 7, and 14.

RESULTS

The administration of SCs provided a rapid but short-lasting effect, whereas the administration of collagen resulted in a delayed but long-lasting wound-healing effect. DCBH resulted in little to no effect. An increase in the perfusion volume of the wound edges accelerated the regeneration process, while the level of microcirculation did not affect the number and activity of fibroblasts. The wound healing acceleration, as well as the new collagen and stratified epithelium formation and maturation, was associated with the presence of a sufficient pool of mature and active fibroblasts in the wound, and not with the number of fibroblasts.

CONCLUSION

The present results clarify the action mechanisms of the studied drugs. In addition, the application purposes and different effects of each drug on the different wound healing phases were demonstrated. An assumption on the multi-component treatment advisability under the wound condition objective assessment possibility was made. Findings from this study may assist clinicians in making an informed transition to personalized wound management and achieve better clinical outcomes.

An Overview of the Use of Equine Collagen as Emerging Material for Biomedical Applications

Type I collagen has always aroused great interest in the field of life-science and bioengineering, thanks to its favorable structural properties and bioactivity. For this reason, in the last five decades it has been widely studied and employed as biomaterial for the manufacture of implantable medical devices. Commonly used sources of collagen are represented by bovine and swine but their applications are limited because of the zoonosis transmission risks, the immune response and the religious constrains. Thus, type-I collagen isolated from horse tendon has recently gained increasing interest as an attractive alternative, so that, although bovine and porcine derived collagens still remain the most common ones, more and more companies started to bring to market a various range of equine collagen-based products. In this context, this work aims to overview the properties of equine collagen making it particularly appealing in medicine, cosmetics and pharmaceuticals, as well as its main biomedical applications and the currently approved equine collagen-based medical devices, focusing on experimental studies and clinical trials of the last 15 years. To the best of our knowledge, this is the first review focusing on the use of equine collagen, as well as on equine collagen-based marketed products for healthcare.

[Mechanisms of the wound-healing action of native collagen type I in ischemic model full-thickness skin wounds on the example - medical devices Collost «(part I)]

Active collagen type I successfully used in regenerative medicine. However, despite the large amount of material of cellular and molecular mechanisms underlying skin repair, the molecular mechanisms of wound healing with use collagen type I, not studied enough.

PURPOSE OF THE STUDY

To study the mechanism of the native collagen type I wound-healing action of native type I collagen on the example of the medical device Collost (7% gel) in a model of the rats difficult-to-heal skin wounds.

MATERIAL AND METHODS

Male rats in population SD (72 individuals) surgically formed an ischemic dorsal skin flap (3×10 cm) with two full-thickness skin wounds 6 mm in diameter.The trained animals divided into 2 groups: in the experimental group, medical device Collost (gel) applied once after the operation, in the control group - a standard medical device for comparison. The dynamics of wound healing assessed, the number of M2 macrophages, myofibroblasts, vascularization and expression of the main markers of the repair process in the wound tissues and time points for assessment were: after 3, 7 and 14 days after operation using macroscopic, immunohistochemical, and molecular methods.

RESULTS

It has been established that the mechanism of action of native collagen type I is associated with the acceleration of the appearance of «progenitorous» M2-macrophages in the wound tissues, decrease in the severity of inflammation or reduction in the duration of the inflammatory stage of the repair process, change in the expression spectrum of number of growth factors, an acceleration of neovasculogenesis.

CONCLUSION

In this work, on the modern experimental model shown regenerative efficiency of a medical device based on collagen type I and described the molecular and cellular processes of wound healing when using it It has been shown that the acceleration of wound healing processes occurs when using a medical device based on native collagen type 1, it is also accompanied by a better aesthetic closure of the damaged skin area.

Comparison of Collagen Granule Dressing Versus Conventional Dressing in Patients With Diabetic Foot Ulcer

Background. Diabetic foot ulcer (DFU) is a difficult, chronic wound with a significant long-term influence on the morbidity, mortality, and quality of life of patients. There is much information about the biochemical features of collagen and its function in wound healing. The aim of this study was to compare the results of DFU patients treated with and without collagen. Methods. A retrospective evaluation was made of the data of patients with DFU who underwent collagen treatment and physiological serum (PS) treatment. The patients were followed-up for a minimum of 12 weeks, and all complications, healing process, and wound characteristics were recorded. Results. Of the total 64 DFU patients included in the study, 30 were treated with PS and 34 with collagen. Complete closure was achieved in 17 (56.6%) of the PS group patients after 12 weeks of treatment. The rate was 25 (73.5%) in the collagen group. The mean duration of treatment was 9.2 weeks (range = 6-12 weeks) in the PS group and 8.08 weeks (range = 5-12 weeks) in the collagen group. The recovery time and recovery rates were determined to be better in the collagen group than in the PS group. Conclusion. A significant reduction in wound size was seen in the collagen group compared with the PS group. The results of this study demonstrated that collagen dressings are better than conventional dressings with regard to early granulation tissue and shorter hospital stay.

Efficacy of A Novel Smart Polymeric Nanodrug in the Treatment of Experimental Wounds in Rats

High-quality and aesthetic wound healing, as well as effective medical support of this process, continue to be relevant. This study aims to evaluate the medical efficacy of a novel smart polymeric nanodrug (SPN) on the rate and mechanism of wound healing in experimental animals. The study was carried out in male Wistar rats (aged 8-9 months). In these animals, identical square wounds down to the fascia were made in non-sterile conditions on the back on both sides of the vertebra. SPN was used for the treatment of one wound, and the other wound was left without treatment (control group). Biocompatible citrate-stabilized cerium oxide nanoparticles integrated into a polysaccharide hydrogel matrix containing natural and synthetic polysaccharide polymers (pectin, alginate, chitosan, agar-agar, water-soluble cellulose derivatives) were used as the therapeutic agent. Changes in the wound sizes (area, volume) over time and wound temperature were assessed on Days 0, 1, 3, 5, 7, and 14. Histological examination of the wounds was performed on Days 3, 7, and 14. The study showed that the use of SPN accelerated wound healing in comparison with control wounds by inhibiting the inflammatory response, which was measured by a decreased number of white blood cells in SPN-treated wounds. It also accelerated the development of fibroblasts, with an early onset of new collagen synthesis, which eventually led to the formation of more tender postoperative scars. Thus, the study demonstrated that the use of SPN for the treatment of wounds was effective and promising.