Porcine mesothelium matrix as a biomaterial for wound healing applications

Diamond-Like Carbon Depositing on the Surface of Polylactide Membrane for Prevention of Adhesion Formation During Tendon Repair

Post-traumatic peritendinous adhesion presents a significant challenge in clinical medicine. This study proposes the use of diamond-like carbon (DLC) deposited on polylactic acid (PLA) membranes as a biophysical mechanism for anti-adhesion barrier to encase ruptured tendons in tendon-injured rats. The results indicate that PLA/DLC composite membrane exhibits more efficient anti-adhesion effect than PLA membrane, with histological score decreasing from 3.12 ± 0.27 to 2.20 ± 0.22 and anti-adhesion effectiveness increasing from 21.61% to 44.72%. Mechanistically, the abundant C=O bond functional groups on the surface of DLC can reduce reactive oxygen species level effectively; thus, the phosphorylation of NF-κB and M1 polarization of macrophages are inhibited. Consequently, excessive inflammatory response augmented by M1 macrophage-originated cytokines including interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) is largely reduced. For biocompatibility evaluation, PLA/DLC membrane is slowly absorbed within tissue and displays prolonged barrier effects compared to traditional PLA membranes. Further studies show the DLC depositing decelerates the release of degradation product lactic acid and its induction of macrophage M2 polarization by interfering esterase and PLA ester bonds, which further delays the fibrosis process. It was found that the PLA/DLC membrane possess an efficient biophysical mechanism for treatment of peritendinous adhesion.

Application of Cartilage Extracellular Matrix to Enhance Therapeutic Efficacy of Methotrexate

BACKGROUND

Rheumatoid arthritis (RA) is characterized by chronic inflammation and joint damage. Methotrexate (MTX), a commonly used disease-modifying anti-rheumatic drug (DMARD) used in RA treatment. However, the continued use of DMARDs can cause adverse effects and result in limited therapeutic efficacy. Cartilage extracellular matrix (CECM) has anti-inflammatory and anti-vascular effects and promotes stem cell migration, adhesion, and differentiation into cartilage cells.

METHODS

CECM was assessed the dsDNA, glycosaminoglycan, collagen contents and FT-IR spectrum of CECM. Furthermore, we determined the effects of CECM and MTX on cytocompatibility in the SW 982 cells and RAW 264.7 cells. The anti-inflammatory effects of CECM and MTX were assessed using macrophage cells. Finally, we examined the in vivo effects of CECM in combination with MTX on anti-inflammation control and cartilage degradation in collagen-induced arthritis model. Anti-inflammation control and cartilage degradation were assessed by measuring the serum levels of RA-related cytokines and histology.

RESULTS

CECM in combination with MTX had no effect on SW 982, effectively suppressing only RAW 264.7 activity. Moreover, anti-inflammatory effects were enhanced when low-dose MTX was combined with CECM. In a collagen-induced arthritis model, low-dose MTX combined with CECM remarkably reduced RA-related and pro-inflammatory cytokine levels in the blood. Additionally, low-dose MTX combined with CECM exerted the best cartilage-preservation effects compared to those observed in the other therapy groups.

CONCLUSION

Using CECM as an adjuvant in RA treatment can augment the therapeutic effects of MTX, reduce existing drug adverse effects, and promote joint tissue regeneration.

Novel neutrophil extracellular trap-related mechanisms in diabetic wounds inspire a promising treatment strategy with hypoxia-challenged small extracellular vesicles

Neutrophil extracellular traps (NETs) have been considered a significant unfavorable factor for wound healing in diabetes, but the mechanisms remain unclear. The therapeutic application of small extracellular vesicles (sEVs) derived from mesenchymal stem cells (MSCs) has received considerable attention for their properties. Hypoxic preconditioning is reported to enhance the therapeutic potential of MSC-derived sEVs in regenerative medicine. Therefore, the aim of this study is to illustrate the detailed mechanism of NETs in impairment of diabetic wound healing and develop a promising NET-targeting treatment based on hypoxic pretreated MSC-derived sEVs (Hypo-sEVs). Excessive NETs were found in diabetic wounds and in high glucose (HG)-induced neutrophils. Further research showed that high concentration of NETs impaired the function of fibroblasts through activating endoplasmic reticulum (ER) stress. Hypo-sEVs efficiently promoted diabetic wound healing and reduced the excessive NET formation by transferring miR-17-5p. Bioinformatic analysis and RNA interference experiment revealed that miR-17-5p in Hypo-sEVs obstructed the NET formation by targeting TLR4/ROS/MAPK pathway. Additionally, miR-17-5p overexpression decreased NET formation and overcame NET-induced impairment in fibroblasts, similar to the effects of Hypo-sEVs. Overall, we identify a previously unrecognized NET-related mechanism in diabetic wounds and provide a promising NET-targeting strategy for wound treatment.

Pyrrolidine Dithiocarbamate-loaded Electrospun Membranes for Peritendinous Anti-adhesion through Inhibition of the Nuclear Factor-κB Pathway

Peritendinous adhesion is a major cause of limb dysfunction and disability in clinical practice. Numerous studies suggest that activation of nuclear factor-κB (NF-κB) pathway in macrophages could be the pivotal figure in excessive collagen synthesis and thus peritendinous adhesion formation. In this study, we assumed this pathological process could be suppressed by inhibiting NF-κB phosphorylation and nuclear translocation using pyrrolidine dithiocarbamate (PDTC), a specific NF-κB inhibitor with the ability to penetrate cell membranes, in macrophages. Then, we conducted electrospinning process to incorporate PDTC into poly(L-lactic) acid (PLA) electrospinning membranes, that is, the PDTC-PLA membranes. Further, with integral film quality and stable drug release property, the PDTC-PLA membranes were subsequently analyzed in the capability and mechanism of preventing adhesion formation both in vitro and in vivo. Our results showed inhibition of macrophage proliferation as well as NF-κB pathway activation from in vitro assays and outstanding promotion in inhibiting NF-κB p65 phosphorylation and reducing adhesion formation from in vivo assays of PDTC-PLA compared to PLA membranes. In conclusion, our findings suggested that PDTC-PLA as an alternative therapeutic approach alleviated inflammation and peritendinous adhesion formation through NF-κB signaling pathway. STATEMENT OF SIGNIFICANCE: Pyrrolidine dithiocarbamate (PDTC) can be blended into poly-L-lactic acid (PLA) fibrous membranes by electrospinning process. This incorporation of PDTC into PLA is an effective way to inhibit proinflammatory activation of macrophages and to achieve advanced anti-adhesion outcome after tendon repair.

Mechanisms of magnesium oxide-incorporated electrospun membrane modulating inflammation and accelerating wound healing

Previously, we demonstrated that magnesium oxide (MgO)-incorporated electrospun membranes show powerful antibacterial activity and promote wound healing, but the underlying mechanisms have not been entirely understood. Herein, we investigated the relationship between structure and function of MgO-incorporated membranes and interrogated critical bioactive cues that contribute to accelerated wound healing and functional restoration. Our results show that MgO-incorporated membranes exhibit good flexibility and improved water vapor transmission rates (WVTRs) and sustained Mg²⁺ release in a simulated model of wounds. MgO-incorporated membranes modulate macrophage phenotype to downregulate inflammatory response, contributing to alleviated inflammation and creating a favorable microenvironment for wound healing. Specifically, MgO-incorporated membranes stimulate macrophages to shift to a pro-healing M2 phenotype and upregulate pro-healing cytokine of transforming growth factor-beta 1 (TGF-β1) and downregulate pro-inflammatory cytokines under lipopolysaccharide (LPS) challenge conditions. Together with increased TGF-β1 by macrophages, MgO-incorporated membranes significantly boost the proliferation of fibroblasts and upregulate collagen production, thus driving granulation tissue formation and wound closure. MgO-incorporated membranes promote angiogenesis by promoting tube formation and upregulating vascular endothelial growth factor (VEGF) production of endothelial cells. Rapid epithelialization of regenerated skin tissue is attributed to the balanced phenotype of keratinocytes between proliferative and terminally differentiated populations. In addition to coordinating keratinocyte phenotype, MgO-incorporated membranes reduce the expression of inflammatory cytokine interleukin 1-alpha (IL-1α) therefore promoting hair follicle regeneration. These data provide mechanisms of MgO-incorporated membranes that inhibit bacterial infection, alleviate inflammation, facilitate extracellular matrix production and epithelialization, and potentiate hair follicle regeneration.

Fibronectin in hyperglycaemia and its potential use in the treatment of diabetic foot ulcers: A review

Metabolism of fibronectin, the protein that plays a key role in the healing of wounds, is changed in the patients with diabetes mellitus. Fibronectin can interact with other proteins and proteoglycans and organise them to form the extracellular matrix, the basis of the granulation tissue in healing wounds. However, diabetic foot ulcers (DFUs) suffer from inadequate deposition of this protein. Degradation prevails over fibronectin synthesis in the proteolytic inflammatory environment in the ulcers. Because of the lack of fibronectin in the wound bed, the assembly of the extracellular matrix and the deposition of the granulation tissue cannot be started. A number of methods have been designed that prevents fibronectin degradation, replace lacking fibronectin or support its formation in non-healing wounds in animal models of diabetes. The aim of this article is to review the metabolism of fibronectin in DFUs and to emphasise that it would be useful to pay more attention to fibronectin matrix assembly in the ulcers when laboratory methods are translated to clinical practice.

Injectable demineralized bone matrix particles and their hydrogel bone grafts loaded with β-tricalcium phosphate powder and granules: A comparative study

Demineralized bone matrix (DBM), has been used as a bone-graft material because of its osteoconductivity and osteoinductivity. However, the previous research report that supports the single use of DBM is limited by its rapid resorption caused by the lack of calcium and phosphate. β-Tricalcium phosphate (TCP) is an enriched calcium phosphate material suitable for bone healing with osteoconductive properties. In this study, we have developed injectable bone graft by the loading two kinds of TCP in DBM particles and thermo-sensitive DBM-derived hydrogel (hDBM). TCP powder (pTCP) and TCP granules (gTCP) were loaded into hDBM and DBM, respectively. The bone formation effect was investigated according to the morphological features of TCP. Residual growth factor concentrations were investigated; microstructure and morphology were characterized by SEM. In-vitro studies showed that hDBM/DBM/pTCP and hDBM/DBM/gTCP bone grafts were biocompatible and could promote osteogenesis by up-regulating the expression of Runx2 and OPN, bone-related genes. In-vivo studies using the rabbit-femur defect model revealed that the implanted hDBM/DBM/pTCP bone graft showed similar histology to that of fibrous dysplasia with the expression of CD68, whereas hDBM/DBM/gTCP showed good bone formation. Loading of gTCP in place of pTCP was noticed as an effective way to improve bone regeneration in an injectable hDBM/DBM hydrogel-based bone graft.

Polymeric biomaterials for wound healing applications: a comprehensive review

Chronic wounds have been a global health threat over the past few decades, requiring urgent medical and research attention. The factors delaying the wound-healing process include obesity, stress, microbial infection, aging, edema, inadequate nutrition, poor oxygenation, diabetes, and implant complications. Biomaterials are being developed and fabricated to accelerate the healing of chronic wounds, including hydrogels, nanofibrous, composite, foam, spongy, bilayered, and trilayered scaffolds. Some recent advances in biomaterials development for healing both chronic and acute wounds are extensively compiled here. In addition, various properties of biomaterials for wound-healing applications and how they affect their performance are reviewed. Based on the recent literature, trilayered constructs appear to be a convincing candidate for the healing of chronic wounds and complete skin regeneration because they mimic the full thickness of skin: epidermis, dermis, and the hypodermis. This type of scaffold provides a dense superficial layer, a bioactive middle layer, and a porous lower layer to aid the wound-healing process. The hydrophilicity of scaffolds aids cell attachment, cell proliferation, and protein adhesion. Other scaffold characteristics such as porosity, biodegradability, mechanical properties, and gas permeability help with cell accommodation, proliferation, migration, differentiation, and the release of bioactive factors.

Fabrication of Sulfated Heterosaccharide/Poly (Vinyl Alcohol) Hydrogel Nanocomposite for Application as Wound Healing Dressing

Nowadays, natural polysaccharides-based hydrogels have achieved promising results as dressings to promote skin healing. In the present study, we prepared a novel hydrogel nanocomposite with poly(vinyl alcohol) (PVA) and sulfated heterosaccharide (UF), named UPH. The SEM results showed that the UPH had dense porous structures with a high porosity and a specific surface area. The UPH had a good swelling property, which can effectively adsorb exudate and keep the wound moist. The in vitro experiments results showed that the UPH was non-cytotoxic and could regulate the inflammatory response and promote the migration of fibroblasts significantly. The phenotypic, histochemistry, and Western blot analyses showed UPH treatment accelerated the wound healing and recovery of skin tissue at wound sites in a C57BL/6 mouse model. Furthermore, the UPH could promote the inflammation process to onset earlier and last shorter than that in a normal process. Given its migration-promoting ability and physicochemical properties, the UPH may provide an effective application for the treatment and management of skin wounds.

Development of decellularization protocol for caprine small intestine submucosa as a biomaterial

Decellularized animal tissues have been proven to be promising biomaterials for various tissue engineering (TE) applications. Among various animal tissues, small intestine submucosa (SIS) has gained attention of many researchers due to its easy availability from the abattoir waste, excellent physicochemical and biological characteristics of a good biomaterial. In this study, Caprine SIS was decellularized to get decellularized caprine SIS (DG-SIS). For decellularization, several physical, chemical and enzymatic protocols have been described in the literature. To optimize the decellularization of caprine SIS, several decellularization protocol (DP), including an in-house developed by us, had been attempted, and effect of the different DPs on the obtained DG-SIS were assessed in terms of decellularization, physiochemical and biological properties. All the DPs differ in terms of decellularization, but three DPs where ionic detergent like sodium dodecyl sulphate (SDS) has been used, largely affect the native composition (e.g. glycosaminoglycans (GAGs)), biological properties and other physiochemical properties of the G-SIS as compared to the DP that uses hypertonic solution of potassium iodide (KI) and non-ionic detergent (TritonX-100). The obtained DG-SISs were fibrous, hemocompatible, biocompatible, hydrophilic, biodegradable and exhibited significant antibacterial activity. Therefore, the DG-SIS will be a prospective biomaterial for TE applications.

Collagen-Based Nanofibers for Skin Regeneration and Wound Dressing Applications

Skin regeneration after an injury is very vital, but this process can be impeded by several factors. Regenerative medicine is a developing biomedical field with the potential to decrease the need for an organ transplant. Wound management is challenging, particularly for chronic injuries, despite the availability of various types of wound dressing scaffolds in the market. Some of the wound dressings that are in clinical practice have various drawbacks such as poor antibacterial and antioxidant efficacy, poor mechanical properties, inability to absorb excess wound exudates, require frequent change of dressing and fails to offer a suitable moist environment to accelerate the wound healing process. Collagen is a biopolymer and a major constituent of the extracellular matrix (ECM), making it an interesting polymer for the development of wound dressings. Collagen-based nanofibers have demonstrated interesting properties that are advantageous both in the arena of skin regeneration and wound dressings, such as low antigenicity, good biocompatibility, hemostatic properties, capability to promote cellular proliferation and adhesion, and non-toxicity. Hence, this review will discuss the outcomes of collagen-based nanofibers reported from the series of preclinical trials of skin regeneration and wound healing.

Wound dressings: curbing inflammation in chronic wound healing

Chronic wounds represent an economic burden to healthcare systems worldwide and a societal burden to patients, deeply impacting their quality of life. The incidence of recalcitrant wounds has been steadily increasing since the population more susceptible, the elderly and diabetic, are rapidly growing. Chronic wounds are characterised by a delayed wound healing process that takes longer to heal under standard of care than acute (i.e. healthy) wounds. Two of the most common problems associated with chronic wounds are inflammation and infection, with the latter usually exacerbating the former. With this in mind, researchers and wound care companies have developed and marketed a wide variety of wound dressings presenting different compositions but all aimed at promoting healing. This makes it harder for physicians to choose the correct therapy, especially given a lack of public quantitative data to support the manufacturers’ claims. This review aims at giving a brief introduction to the clinical need for chronic wound dressings, focusing on inflammation and evaluating how bio-derived and synthetic dressings may control excess inflammation and promote healing.

Scaffold-based developmental tissue engineering strategies for ectodermal organ regeneration

Tissue engineering (TE) is a multidisciplinary research field aiming at the regeneration, restoration, or replacement of damaged tissues and organs. Classical TE approaches combine scaffolds, cells and soluble factors to fabricate constructs mimicking the native tissue to be regenerated. However, to date, limited success in clinical translations has been achieved by classical TE approaches, because of the lack of satisfactory biomorphological and biofunctional features of the obtained constructs. Developmental TE has emerged as a novel TE paradigm to obtain tissues and organs with correct biomorphology and biofunctionality by mimicking the morphogenetic processes leading to the tissue/organ generation in the embryo. Ectodermal appendages, for instance, develop in vivo by sequential interactions between epithelium and mesenchyme, in a process known as secondary induction. A fine artificial replication of these complex interactions can potentially lead to the fabrication of the tissues/organs to be regenerated. Successful developmental TE applications have been reported, in vitro and in vivo, for ectodermal appendages such as teeth, hair follicles and glands. Developmental TE strategies require an accurate selection of cell sources, scaffolds and cell culture configurations to allow for the correct replication of the in vivo morphogenetic cues. Herein, we describe and discuss the emergence of this TE paradigm by reviewing the achievements obtained so far in developmental TE 3D scaffolds for teeth, hair follicles, and salivary and lacrimal glands, with particular focus on the selection of biomaterials and cell culture configurations.

Extracellular matrix-based biomaterials as adipose-derived stem cell delivery vehicles in wound healing: a comparative study between a collagen scaffold and two xenografts

BACKGROUND

Stem cell therapies represent a promising tool in regenerative medicine. Considering the drawbacks of direct stem cell injections (e.g. poor cell localisation), extracellular matrix-based biomaterials (e.g. scaffolds and tissue grafts), due to their compositional biofunctionality and cytocompatibility, are under investigation as potential stem cell carriers.

METHODS

The present study assessed the potential of three commercially available extracellular matrix-based biomaterials [a collagen/glycosaminoglycan scaffold (Integra™ Matrix Wound Dressing), a decellularised porcine peritoneum (XenoMEM™) and a porcine urinary bladder (MatriStem™)] as human adipose-derived stem cell delivery vehicles.

RESULTS

Both tissue grafts induced significantly (p < 0.01) higher human adipose-derived stem cell proliferation in vitro over the collagen scaffold, especially when the cells were seeded on the basement membrane side. Human adipose-derived stem cell phenotype and trilineage differentiation potential was preserved in all biomaterials. In a splinted wound healing nude mouse model, in comparison to sham, biomaterials alone and cells alone groups, all biomaterials seeded with human adipose-derived stem cells showed a moderate improvement of wound closure, a significantly (p < 0.05) lower wound gap and scar index and a significantly (p < 0.05) higher proportion of mature collagen deposition and angiogenesis (the highest, p < 0.01, was observed for the cell loaded at the basement membrane XenoMEM™ group). All cell-loaded biomaterial groups retained more cells at the implantation side than the direct injection group, even though they were loaded with half of the cells than the cell injection group.

CONCLUSIONS

This study further advocates the use of extracellular matrix-based biomaterials (in particular porcine peritoneum) as human adipose-derived stem cell delivery vehicles. Comparative analysis of a collagen scaffold (Integra™ Matrix Wound Dressing) and two tissue grafts [decellularised porcine peritoneum (XenoMEM™) and porcine urinary bladder (MatriStem™)] as human adipose-derived stem cells carriers.