A photocrosslinking antibacterial decellularized matrix hydrogel with nanofiber for cutaneous wound healing

Decellularized human amniotic member hydrogel promotes limbal stem cells proliferation

Allogeneic cultured limbal epithelial stem cell transplantation has shown variable clinical success in treating limbal stem cell deficiency, low success cases are likely due to insufficient stem cell quantity or functional impairment. In this study, we engineered a decellularized amniotic membrane hydrogel (dAM-gel) using a freeze-thaw protocol designed to retain extracellular matrix integrity. Post-processing, collagen content decreased modestly from 313.50 ± 27.89 μg/mg to 284.8 ± 14.82 μg/mg (P = 0.08), while glycosaminoglycan levels shifted from 7.20 ± 1.66 μg/mg to 6.28 ± 0.55 μg/mg (P = 0.27). Crucially, the protocol achieved near-complete DNA removal (7.41 ± 0.78 μg/mg vs. 0.14 ± 0.06 μg/mg) (P < 0.0001), ensuring minimal immunogenicity. Although the dAM-gel demonstrates limited gelation capacity at lower concentrations, it achieves robust gelation at 14 mg/ml, completing the process within 28.26 ± 1.21 minutes. Furthermore, dAM-gel facilitates the migration and proliferation of limbal stem cells, particularly p63 + cells, which are known to correlate with the success of clinical treatments. A plausible explanation for this phenomenon is that dAM-gel contains a high concentration of agrin, which facilitates the proliferation of limbal stem cells while preserving their stemness via the Yap1-cyclin D1 signaling pathway. In conclusion, dAM-gel derived from amniotic membrane presents therapeutic promise for treating limbal stem cell deficiency by enhancing the proliferation of limbal stem cells while maintaining their stem cell phenotype.

Regional-Specific Decellularized Meniscus Extracellular Matrix Elastic Nanofiber Aerogels Regulate Meniscal Regeneration and Vascularization

The meniscus is a heterogeneous structure with spatial distribution of cells and vessels. Promoting meniscus healing remains challenging, especially in its avascular inner region. The ideal repair mode shall promote meniscus repair while maintaining local avascularity to prevent pathological changes from vascular invasion. Given the natural biochemical components of native meniscus, decellularized meniscus extracellular matrix (dmECM) shows promise for meniscus repair. Compared to homogeneous dmECM, regional-specific dmECM (RS-dmECM) appears to offer greater potential for constructing heterogeneous meniscus structures. Furthermore, there is currently no study on the effects of RS-dmECM on vascularization. Thus, RS-dmECM is prepared and found dmECM-Outer induced stem cells fibrochondrogenic differentiation, while dmECM-Inner induced the chondrogenic differentiation and inhibited angiogenesis through suppressing the peroxisome proliferators-activated receptors signaling pathway. Subsequently, regional-specific poly(lactic acid)/gelatin/dmECM elastic 3D nanofiber aerogels (PG-dmECM) are fabricated to repair meniscal avascular area defects in a rabbit model. The PG-Outer promotes meniscal fibrocartilage regeneration without a significant effect on vascular invasion. In contrast, the PG-Inner achieves meniscal cartilage regeneration and inhibits vascular invasion. Moreover, the compressive stress can reach 117 kPa, comparable to that of the avascular area. This PG-Inner may have the potential to promote meniscal cartilage regeneration and prevent pathological changes within the avascular area.

Research Progress on Extracellular Matrix-Based Composite Materials in Antibacterial Field

Due to their exceptional cell compatibility, biodegradability, and capacity to trigger tissue regeneration, extracellular matrix (ECM) materials have drawn considerable attention in tissue healing and regenerative medicine. Interestingly, these materials undergo continuous degradation and release antimicrobial peptides (AMPs) while simultaneously promoting tissue regeneration, thereby exerting a potent antibacterial effect. On this basis, a variety of basic properties of ECM materials, such as porous adsorption, hydrophilic adsorption, group crosslinking, and electrostatic crosslinking, can be used to facilitate the integration of ECM materials and antibacterial agents through physical and chemical approaches in order to enhance the antibacterial efficacy. This article reviews the recent advancements in the study of ECM antibacterial materials, including the antibacterial function and antibacterial mechanism of free-standing ECM materials and ECM-based composite materials. In addition, the urgent challenges and future research prospects of ECM materials in the anti-infection industry are discussed.

Polysaccharide- and protein-based hydrogel dressings that enhance wound healing: A review

Hydrogels can possess desired biochemical and mechanical properties, excellent biocompatibility, satisfactory biodegradability, and biological capabilities that promote skin repair, making them ideal candidates for skin healing dressings. Polysaccharides, such as chitosan, hyaluronic acid and sodium alginate as well as proteins, including gelatin, collagen and fibroin proteins, are biological macromolecules celebrated for their biocompatibility and biodegradability, are at the forefront of innovative hydrogel dressing development. This work first summarizes the skin wound healing process and its influencing factors, and then systematically articulates the multifunctional roles of hydrogels based on biological macromolecules (polysaccharides and proteins) as dressing in addressing bacterial infection, hemorrhage and inflammation during wound healing. Furthermore, this review explores the potential of these hydrogels as vehicles for combination therapy, by incorporating growth factors or stem cells. Finally, the article offers insights into future directions of such hydrogels in wound repair field.

Asymmetric chitosan-derivative/carboxymethylcellulose layer-by-layer film combining antimicrobial and vascular regeneration for the repair of infected wounds

Bacterially infected wounds are a serious threat to patients' lives and health, and multifunctional dressings with antimicrobial properties and healing promotion are urgently needed. Thus, we used the cationic and anionic properties of chitosan (CS)-nerol (N) derivative (CSN) and carboxymethylcellulose (CMC) to prepare asymmetric layer-by-layer self-assembled (LBL) composite films (CSN-CMC LBL films) with antibacterial and healing properties using a spin-coating method. SEM images showed that the CSN-CMC LBL films had completely different degrees of roughness at the bottom (hydrophilic layer) and at the top (hydrophobic layer), with the roughness at the top increasing as the number of layers increased. The CSN and CMC were used to prepare asymmetric LBL films via the electrostatic attraction of -COO- and NH3+. In addition, adhesion and water contact angle tests showed that the CSN-CMC LBL films had enhanced tissue adhesion and good hydrophobicity. These materials had excellent antimicrobial activity and good biocompatibility. Importantly, the animal infection model results showed that CSN-CMC-8 LBL films effectively eliminated the infection in vivo, inhibited inflammation, promoted vascular regeneration, accelerated the epithelialization process, and achieved high quality healing. Overall, the CSN-CMC LBL films in this study showed considerable potential for application in infected wound healing.

Extracellular Matrix-Bioinspired Anisotropic Topographical Cues of Electrospun Nanofibers: A Strategy of Wound Healing through Macrophage Polarization

The skin serves as the body's outermost barrier and is the largest organ, providing protection not only to the body but also to various internal organs. Owing to continuous exposure to various external factors, it is susceptible to damage that can range from simple to severe, including serious types of wounds such as burns or chronic wounds. Macrophages play a crucial role in the entire wound-healing process and contribute significantly to skin regeneration. Initially, M1 macrophages infiltrate to phagocytose bacteria, debris, and dead cells in fresh wounds. As tissue repair is activated, M2 macrophages are promoted, reducing inflammation and facilitating restoration of the dermis and epidermis to regenerate the tissue. This suggests that extracellular matrix (ECM) promotes cell adhesion, proliferation, migrationand macrophage polarization. Among the numerous strategies, electrospinning is a versatile technique for obtaining ECM-mimicking structures with anisotropic and isotropic topologies of micro/nanofibers. Various electrospun biomaterials influence macrophage polarization based on their isotropic or anisotropic topologies. Moreover, these fibers possess a high surface-area-to-volume ratio, promoting the effective exchange of vital nutrients and oxygen, which are crucial for cell viability and tissue regeneration. Micro/nanofibers with diverse physical and chemical properties can be tailored to polarize macrophages toward skin regeneration and wound healing, depending on specific requirements. This review describes the significance of micro/nanostructures for activating macrophages and promoting wound healing.

Instant trachea reconstruction using 3D-bioprinted C-shape biomimetic trachea based on tissue-specific matrix hydrogels

Currently, 3D-bioprinting technique has emerged as a promising strategy to offer native-like tracheal substitutes for segmental trachea reconstruction. However, there has been very limited breakthrough in tracheal repair using 3D-bioprinted biomimetic trachea owing to the lack of ideal bioinks, the requirement for precise structural biomimicking, and the complexity of multi-step surgical procedures by mean of intramuscular pre-implantation. Herein, we propose a one-step surgical technique, namely direct end-to-end anastomosis using C-shape 3D-bioprinted biomimetic trachea, for segmental trachea defect repair. First, two types of tissue-specific matrix hydrogels were exploited to provide mechanical and biological microenvironment conducive to the specific growth ways of cartilage and fibrous tissue respectively. In contrast to our previous O-shape tracheal design, the tubular structure of alternating C-shape cartilage rings and connecting vascularized-fibrous-tissue rings was meticulously designed for rapid 3D-bioprinting of tracheal constructs with optimal printing paths and models. Furthermore, in vivo trachea regeneration in nude mice showed satisfactory mechanical adaptability and efficient physiological regeneration. Finally, in situ segmental trachea reconstruction by direct end-to-end anastomosis in rabbits was successfully achieved using 3D-bioprinted C-shape biomimetic trachea. This study demonstrates the potential of advanced 3D-bioprinting for instant and efficient repair of segmental trachea defects.

Advances in antimicrobial hydrogels for dental tissue engineering: regenerative strategies for endodontics and periodontics

Dental tissue infections have been affecting millions of patients globally leading to pain, severe tissue damage, or even tooth loss. Commercial sterilizers may not be adequate to prevent frequent dental infections. Antimicrobial hydrogels have been introduced as an effective therapeutic strategy for endodontics and periodontics since they have the capability of imitating the native extracellular matrix of soft tissues. Hydrogel networks are considered excellent drug delivery platforms due to their high-water retention capacity. In this regard, drugs or nanoparticles can be incorporated into the hydrogels to endow antimicrobial properties as well as to improve their regenerative potential, once biocompatibility criteria are met avoiding high dosages. Herein, novel antimicrobial hydrogel formulations were discussed for the first time in the scope of endodontics and periodontics. Such hydrogels seem outstanding candidates especially when designed not only as simple volume fillers but also as smart biomaterials with condition-specific adaptability within the dynamic microenvironment of the defect site. Multifunctional hydrogels play a pivotal role against infections, inflammation, oxidative stress, etc. along the way of dental regeneration. Modern techniques (e.g., 3D and 4D-printing) hold promise to develop the next generation of antimicrobial hydrogels together with their limitations such as infeasibility of implantation.

Nano drug delivery systems: a promising approach to scar prevention and treatment

Scar formation is a common physiological process that occurs after injury, but in some cases, pathological scars can develop, leading to serious physiological and psychological effects. Unfortunately, there are currently no effective means to intervene in scar formation, and the structural features of scars and their unclear mechanisms make prevention and treatment even more challenging. However, the emergence of nanotechnology in drug delivery systems offers a promising avenue for the prevention and treatment of scars. Nanomaterials possess unique properties that make them well suited for addressing issues related to transdermal drug delivery, drug solubility, and controlled release. Herein, we summarize the recent progress made in the use of nanotechnology for the prevention and treatment of scars. We examine the mechanisms involved and the advantages offered by various types of nanomaterials. We also highlight the outstanding challenges and questions that need to be addressed to maximize the potential of nanotechnology in scar intervention. Overall, with further development, nanotechnology could significantly improve the prevention and treatment of pathological scars, providing a brighter outlook for those affected by this condition.

Evaluation of Natural Protein-based Nanofiber Composite Photocrosslinking Hydrogel for skin wound regeneration

Protein based photocrosslinking hydrogels with nanofiber dispersions were reported to be an effective wound dressing. In this study, two kinds of protein (gelatin and decellularized dermal matrix) were modified to obtain GelMA and ddECMMA, respectively. Poly(ε-caprolactone) nanofiber dispersions (PCLPBA) and thioglycolic acid-modified chitosan (TCS) were added into GelMA solution and ddECMMA solution, respectively. After photocrosslinking, four kinds of hydrogel (GelMA, GTP4, DP and DTP4) were fabricated. The hydrogels showed excellent physico-chemical property, biocompatibility and negligible cytotoxicity. When applied on the full-thickness cutaneous deficiency of SD rats, hydrogel treated groups exhibited an enhanced wound healing effect than Blank group. Besides, the histological staining of H&E and Masson's showed that hydrogels groups with PCLPBA and TCS (GTP4 and DTP4) improved wound healing. Furthermore, GTP4 group performed better healing effect than other groups, which had great potential in skin wound regeneration.

Mussel-inspired methacrylated gelatin-dopamine/quaternized chitosan/glycerin sponges with self-adhesion, antibacterial activity, and hemostatic ability for wound dressings

It is one of the most emergent challenges to prepare wound dressings for quickly and effectively controlling profuse bleeding in clinical surgery and emergent accident. In this work, a novel strategy has been developed to prepare methacrylated gelatin-dopamine (GelMA-DA)/quaternized chitosan (QCS)/glycerol (Gly) composite sponges with good biocompatibility, tissue self-adhesion, antibacterial activity, and hemostatic ability. Results show that the GelMA-DA/QCS/Gly sponges display good biocompatibility and water absorption capacity. The lap shear strength of the GelMA-DA/QCS/Gly sponge with the GelMA-DA content of 5 W/V% is approximately 128.36 ± 8.45, 125.17 ± 7.18, 138.29 ± 7.94, and 113.83 ± 9.28 kPa for skin, liver, muscle, and fat, respectively. The GelMA-DA/QCS/Gly sponge displays better antibacterial activity against Gram positive and negative bacteria than the commercial Gelatin hemostatic sponge and CS hemostatic sponge. Animal experiments using rat tail and liver bleeding model show that the hemostasis time and blood loss in the GelMA-DA/QCS/Gly sponge group is approximately 33.3 ± 6.7 s and 0.19 ± 0.05 g, respectively, which is also better than that of the commercial Gelatin hemostatic sponge and CS hemostatic sponge. These results demonstrate promising potential of the GelMA-DA/QCS/Gly sponges for applications as hemostatic wound dressings in clinical surgery and emergent treatment.

Modulation of Macrophage Function by Bioactive Wound Dressings with an Emphasis on Extracellular Matrix-Based Scaffolds and Nanofibrous Composites

Bioactive wound dressings that are capable of regulating the local wound microenvironment have attracted a very large interest in the field of regenerative medicine. Macrophages have many critical roles in normal wound healing, and the dysfunction of macrophages significantly contributes to impaired or non-healing skin wounds. Regulation of macrophage polarization towards an M2 phenotype provides a feasible strategy to enhance chronic wound healing, mainly by promoting the transition of chronic inflammation to the proliferation phase of wound healing, upregulating the level of anti-inflammatory cytokines around the wound area, and stimulating wound angiogenesis and re-epithelialization. Based on this, modulation of macrophage functions by the rational design of bioactive scaffolds has emerged as a promising way to accelerate delayed wound healing. This review outlines current strategies to regulate the response of macrophages using bioactive materials, with an emphasis on extracellular matrix-based scaffolds and nanofibrous composites.

Effects and Progress of Photo-Crosslinking Hydrogels in Wound Healing Improvement

Wound healing is a dynamic physiological process, including three stages: inflammation, tissue formation, and remodeling. The quality of wound healing is affected by many topical and systemic factors, while any small factor may affect the process. Therefore, improving the quality of wound healing is a complex and arduous challenge. Photo-crosslinking reaction using visible light irradiation is a novel method for hydrogel preparation. Photo-crosslinking hydrogels can be controlled in time and space, and are not interfered by temperature conditions, which have been widely used in the fields of medicine and engineering. This review aims to summarize the application of photo-crosslinking hydrogels in improving the quality of wound healing, mainly including the material design, application mechanism, and effect of photo-crosslinking hydrogels applied in wound healing, followed by the applicable animal models for experimental research. Finally, this review analyzes the clinical application prospects of photo-crosslinking hydrogels in the field of wound healing.