Vessel-Derived Decellularized Extracellular Matrices (VdECM): Novel Bio-Engineered Materials for the Wound Healing

Extracellular Matrix-Mediated Crosslinking of Adhesive Hyaluronic Acid Patch for Treating Volumetric Muscle Injury

The treatment of volumetric muscle loss (VML) is challenging owing to the deficiency of appropriate bioscaffolds and ineffective therapeutic outcomes with conventional approaches. Adhesive hydrogels have emerged as potential tools for promoting tissue regeneration, offering effective integration with damaged tissues. However, technical procedures requiring non-biocompatible crosslinking methods, mechanical mismatches, or the absence of tissue-specific microenvironments in conventional adhesive hydrogels have hindered their successful application in tissue reconstruction. In this study, a patch-type adhesive hydrogel is developed by combining a muscle tissue-derived extracellular matrix (MEM) and catechol-conjugated hyaluronic acid (HA-CA). This MEM-containing HA-CA (HCM) patch hydrogel utilizes MEM as both a biocompatible crosslinker and a therapeutic substance. The HCM patch hydrogel, crosslinked through a combination of covalent and non-covalent interactions via MEM and catechol in the composite, not only provides stable physical support but also develops muscle tissue-specific biochemical cues, mediating the recruitment and maturation of muscular cells. In animal models of VML, the HCM patch hydrogel effectively stimulates satellite cells and supports de novo muscle regeneration with functional restoration. This study emphasizes the efficacy and ready-to-use convenience of HCM patch hydrogels for muscle regeneration.

Decellularized Extracellular Matrix Scaffold Loaded with Regulatory T Cell-Conditioned Medium Induces M2 Macrophage Polarization

Biomaterials often induce local inflammatory responses following implantation. Scaffolds that cause continuous M1 polarization typically hinder tissue healing and regeneration. Regulating the transformation of macrophages to the M2 phenotype in the inflammatory environment is crucial. We propose that regulatory T cell-conditioned medium (Treg CM) effectively promotes M2 polarization of macrophages induced by decellularized extracellular matrix (dECM) materials in inflammatory environments. In vitro results showed that in the presence of dECM, Treg CM induces the polarization of RAW264.7 macrophages to M2 and inhibits M1 macrophage polarization under inflammatory conditions (lipopolysaccharide + IFN-γ). Additionally, dECM promotes the polarization of bone marrow-derived macrophages (BMDMs) to M2, while Treg CM further promotes M2 polarization and inhibits M1 polarization in an inflammatory environment. These findings were confirmed by transcriptome sequencing. Treg CM inhibited IκB kinase/NF-κB signaling and cellular responses to oxidative stress. In vivo subcutaneous transplantation showed an increase in M2 macrophages, a decrease in M1 macrophages, and an increased M2/M1 ratio in dECM materials loaded with Treg CM. These results suggest that Treg CM can create a pro-M2 polarized microenvironment for dECM, guiding immune responses toward favorable tissue regeneration. Ultimately, this research highlights the potential of Treg CM as a therapeutic approach to modulate the immune response and improve the efficacy of regenerative biomaterials.

Decellularized Extracellular Matrix Scaffolds: Recent Advances and Emerging Strategies in Bone Tissue Engineering

Bone tissue engineering (BTE) is a complex biological process involving the repair of bone tissue with proper neuronal network and vasculature as well as bone surrounding soft tissue. Synthetic biomaterials used for BTE should be biocompatible, support bone tissue regeneration, and eventually be degraded in situ and replaced with the newly generated bone tissue. Recently, various forms of bone graft materials such as hydrogel, nanofiber scaffolds, and 3D printed composite scaffolds have been developed for BTE application. Decellularized extracellular matrix (DECM), a kind of natural biological material obtained from specific tissues and organs, has certain advantages over synthetic and exogenous biomaterial-derived bone grafts. Moreover, DECM can be developed from a wide range of biological sources and possesses strong molding abilities, natural 3D structures, and bioactive factors. Although DECM has shown robust osteogenic, proangiogenic, immunomodulatory, and bone defect healing potential, the rapid degradation and limited mechanical properties should be improved for bench-to-bed translation in BTE. This review summarizes the recent advances in DECM-based BTE and discusses emerging strategies of DECM-based BTE.

Floating electrode-dielectric barrier discharge-based plasma promotes skin regeneration in a full-thickness skin defect mouse model

Wound healing involves a complex and dynamic interplay among various cell types, cytokines, and growth factors. Macrophages and transforming growth factor-β1 (TGF-β1) play an essential role in different phases of wound healing. Cold atmospheric plasma has a wide range of applications in the treatment of chronic wounds. Hence, we aimed to investigate the safety and efficacy of a custom-made plasma device in a full-thickness skin defect mouse model. Here, we investigated the wound tissue on days 6 and 12 using histology, qPCR, and western blotting. During the inflammation phase of wound repair, macrophages play an important role in the onset and resolution of inflammation, showing decreased F4/80 on day 6 of plasma treatment and increased TGF-β1 levels. The plasma-treated group showed better epidermal epithelialization, dermal fibrosis, collagen maturation, and reduced inflammation than the control group. Our findings revealed that floating electrode-dielectric barrier discharge (FE-DBD)-based atmospheric-pressure plasma promoted significantly faster wound healing in the plasma-treated group than that in the control group with untreated wounds. Hence, plasma treatment accelerated wound healing processes without noticeable side effects and suppressed pro-inflammatory genes, suggesting that FE-DBD-based plasma could be a potential therapeutic option for treating various wounds.

Biofabrication of engineered blood vessels for biomedical applications

To successfully engineer large-sized tissues, establishing vascular structures is essential for providing oxygen, nutrients, growth factors and cells to prevent necrosis at the core of the tissue. The diameter scale of the biofabricated vasculatures should range from 100 to 1,000 µm to support the mm-size tissue while being controllably aligned and spaced within the diffusion limit of oxygen. In this review, insights regarding biofabrication considerations and techniques for engineered blood vessels will be presented. Initially, polymers of natural and synthetic origins can be selected, modified, and combined with each other to support maturation of vascular tissue while also being biocompatible. After they are shaped into scaffold structures by different fabrication techniques, surface properties such as physical topography, stiffness, and surface chemistry play a major role in the endothelialization process after transplantation. Furthermore, biological cues such as growth factors (GFs) and endothelial cells (ECs) can be incorporated into the fabricated structures. As variously reported, fabrication techniques, especially 3D printing by extrusion and 3D printing by photopolymerization, allow the construction of vessels at a high resolution with diameters in the desired range. Strategies to fabricate of stable tubular structures with defined channels will also be discussed. This paper provides an overview of the many advances in blood vessel engineering and combinations of different fabrication techniques up to the present time.

Decellularized matrix bioink with gelatin methacrylate for simultaneous improvements in printability and biofunctionality

Gelatin methacrylate (GelMA) bioink has been widely used in bioprinting because it is a printable and biocompatible biomaterial. However, it is difficult to print GelMA bioink without any temperature control because it has a thermally-sensitive rheological property. Therefore, in this study, we developed a temperature-controlled printing system in real time without affecting the viability of the cells encapsulated in the bioink. In addition, a skin-derived decellularized extracellular matrix (SdECM) was printed with GelMA to better mimic the native tissue environment compared with solely using GelMA bioink with the enhancement of structural stability. The temperature setting accuracy was calculated to be 98.58 ± 1.8 % for the module and 99.48 ± 1.33 % for the plate from 5 °C to 37 °C. The group of the temperature of the module at 10 °C and the plate at 20 °C have 93.84 % cell viability with the printable range in the printability window. In particular, the cell viability and proliferation were increased in the encapsulated fibroblasts in the GelMA/SdECM bioink, relative to the GelMA bioink, with a morphology that significantly spread for seven days. The gene expression and growth factors related to skin tissue regeneration were relatively upregulated with SdECM components. In the bioprinting process, the rheological properties of the GelMA/SdECM bioink were successfully adjusted in real time to increase printability, and the native skin tissue mimicked components providing tissue-specific biofunctions to the encapsulated cells. The developed bioprinting strategies and bioinks could support future studies related to the skin tissue reconstruction, regeneration, and other medical applications using the bioprinting process.