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Tissue repair and regeneration have long been a focus of research, with growing evidence highlighting the role played by immunomodulation. The repair of tissue cells can be significantly promoted through the localized immunomodulation of tissues. Hydrogels are increasingly used in this field due to their biocompatibility, versatility, and relative ease of fabrication. This Review highlights the critical role of inflammation and immune development in the complex process of tissue repair after injury, highlighting the dynamic interactions between immune cells that ultimately influence the outcome of tissue healing. We also summarize the precise functions of immune cells and their responses in various tissue injury scenarios, which are critical for harnessing the full potential of immunomodulatory strategies to promote tissue repair. We discuss recent advances in drug-carrying hydrogels, which offer promising avenues for tissue regeneration with precise control of the immune environment for constructive tissue repair. Further advances in our understanding of the mechanisms driving inflammation and immune cell behavior during tissue injury are expected to foster the development of increasingly effective hydrogel-based immunomodulatory strategies to promote tissue repair and regeneration.

The oral and maxillofacial regions perform mastication, swallowing, speech, and expression; therefore, oral and maxillofacial tissue defects can seriously affect patient physical and mental health. Biomaterials can be used to repair maxillofacial defects. However, traditional biomaterials lack biocompatibility and cannot accurately match the shape of damaged tissues, leading to tissue immune rejection and chronic inflammation, thereby limiting their repair ability. Biomaterials can improve mesenchymal stem cell (MSC) survival by simulating the extracellular matrix (ECM). MSCs have excellent self-regenerative abilities and can differentiate into almost all cell types, making them valuable for tissue engineering. This review summarizes biomaterial-based, stem cell, and cell-free therapies and discusses their properties, advantages, disadvantages, and application mechanisms, with a particular focus on their use in oral and maxillofacial tissue defect repair and regeneration and the limitations of the current materials and strategies. This review provides insights into using biomaterials for oral and maxillofacial tissue defect repair and regeneration.

Advances in the development and utilization of polysaccharide materials are highly promising, offering prominent applications in the field of tissue engineering for addressing diverse clinical needs, including wound healing, bone regeneration, cartilage repair, and treatment of conditions such as arthritis. Novel polysaccharide materials are popular owing to their inherent stability, biocompatibility, and repeatability. This review presents an overview of the biomedical applications of natural polysaccharide hydrogels and their derivatives. Herein, we discuss the latest advancements in the fabrication, physicochemical properties, and biomedical applications of polysaccharide-based hydrogels, including chitosan, hyaluronic acid, alginate, and cellulose. Various processing techniques applicable to polysaccharide materials are explored, such as the transformation of polysaccharide hydrogels into electrospun nanofibers, microneedles, microspheres, and nanogels. Furthermore, the use of polysaccharide hydrogels in the context of wound-healing applications, including hemostatic effects, antimicrobial activities, anti-inflammatory properties, and promotion of angiogenesis, is presented. Finally, we address the challenges encountered in the development of polysaccharide hydrogels and outline the potential prospects in this evolving field.

Bacterial infection is one of the main causes of delayed wound healing. Hence, the development of antimicrobial dressings with good biocompatibility has high clinical significance and social value. The natural macromolecule, serum albumin, has superior biocompatibility, low immunogenicity, and a good drug-carrying capacity. In this study, human serum albumin (HSA) was modified with methacrylic anhydride to obtain photo-crosslinking properties. Then, the photo-crosslinking HSA was applied to produce homogenized microspheres (HMS) through the nitrogen elution-assisted microfluidic technique and ultraviolet light. Effective loading of vascular endothelial growth factor (VEGF) was achieved by utilizing the adsorption of HSA onto zinc ions and their crosslinking with His-tagged VEGF. The prepared HMS-Zn@VEGF exhibited broad-spectrum antibacterial activity and simultaneously exerted proangiogenic effects in vitro, effectively promoting the healing of infected wounds in rats. In vivo experiments using rats showed that HMS-Zn@VEGF promoted the deposition of collagen around the wound, improved the local inflammatory response, and promoted angiogenesis. In conclusion, our prepared HMS-Zn@VEGF microspheres have good biocompatibility, antimicrobial properties, and angiogenic ability, which can be used for infected wound healing.

Cell growth and metabolism require an adequate supply of oxygen. However, obtaining sufficient oxygen from the blood circulating around diabetic wounds is challenging. Nevertheless, achieving a continuous and stable oxygen supply is required for these wounds to heal. Hence, in this study, we report a novel antibacterial oxygen-producing silk fibroin methacryloyl hydrogel microneedle (MN) patch comprising tips encapsulated with calcium peroxide and catalase and a base coated with antibacterial Ag nanoparticles (AgNPs). The tip of the MN patch continuously releases oxygen and inhibits the production of reactive oxygen species. This accelerates diabetic wound healing by promoting cellular accretion and migration, macrophage M2 polarization, and angiogenesis. The AgNPs at the base of the MN patch effectively combat microbial infection, further facilitating wound repair. These findings suggest that using this multifunctional oxygen-producing MN patch may be a promising strategy for diabetic wound healing in clinical settings.

The development of new wound dressings has always been an issue of great clinical importance and research promise. In this study, we designed a novel double cross-linked polysaccharide hydrogel microspheres based on alginate (ALG) and hyaluronic acid methacrylate (HAMA) from gas-assisted microfluidics for wound healing. The microspheres from gas-assisted microfluidics showed an uniform size and good microsphere morphology. Moreover, this composite polysaccharide hydrogel microspheres were constructed by harnessing the fact that zinc ions (Zn2+) can cross-link with ALG as well as histidine-tagged vascular endothelial growth (His-VEGF) to achieve long-term His-VEGF release, thus promoting angiogenesis and wound healing. Meanwhile, Zn2+, as an important trace element, can exert antibacterial and anti-inflammatory effects, reshaping the trauma microenvironment. In addition, photo cross-linked HAMA was introduced into the microspheres to further improve its mechanical properties and drug release ability. In summary, this novel Zn2+ composite polysaccharide hydrogel microspheres loaded with His-VEGF based on a dual cross-linked strategy exhibited synergistic antimicrobial and angiogenic effects in promoting wound healing.

Spinal cord injury (SCI) is characterized by damage resulting in dysfunction of the spinal cord. Hydrogels are common biomaterials that play an important role in the treatment of SCI. Hydrogels are biocompatible, and some have electrical conductivity that are compatible with spinal cord tissues. Hydrogels have a high drug-carrying capacity, allowing them to be used for SCI treatment through the loading of various types of active substances, drugs, or cells. We first discuss the basic anatomy and physiology of the human spinal cord and briefly discuss SCI and its treatment. Then, we describe different treatment strategies for SCI. We further discuss the crosslinking methods and classification of hydrogels and detail hydrogel biomaterials prepared using different processing methods for the treatment of SCI. Finally, we analyze the future applications and limitations of hydrogels for SCI. The development of biomaterials opens up new possibilities and options for the treatment of SCI. Thus, our findings will inspire scholars in related fields and promote the development of hydrogel therapy for SCI.

Purpose: The pathogenesis of thymoma (THYM) remains unclear, and there is no uniform measurement standard for the complexity of THYM derived from different thymic epithelial cells. Consequently, it is necessary to develop novel biomarkers of prognosis estimation for patients with THYM.Methods: Consensus clustering and single-sample gene-set enrichment analysis were used to divide THYM samples into different immunotypes. Differentially expressed genes (DEGs) between those immunotypes were used to do the Kyoto Encyclopedia of Genes and Genomes analysis, Gene Ontology annotations, and protein-protein interaction network. Furthermore, the survival-related DEGs were used to construct prognostic model with lasso regression. The model was verified by survival analysis, receiver operating characteristic curve, and principal component analysis. Furthermore, the correlation coefficients of stemness index and riskscore, tumor mutation burden (TMB) and riskscore, drug sensitivity and gene expression were calculated with Spearman method.Results: THYM samples were divided into immunotype A and immunotype B. A total of 707 DEGs were enriched in various cancer-related or immune-related pathways. An 11-genes signature prognostic model (CELF5, ODZ1, CD1C, DRP2, PTCRA, TSHR, HKDC1, KCTD19, RFX8, UGT3A2, and PRKCG) was constructed from 177 survival-related DEGs. The prognostic model was significantly related to overall survival, clinical features, immune cells, TMB, and stemness index. The expression of some genes were significantly related to drug sensitivity.Conclusion: For the first time, a prognostic model of 11 genes was identified based on the immune microenvironment in patients with THYM, which may be helpful for diagnosis and prediction. The associated factors (immune microenvironment, mutation status, and stemness) may be useful for exploring the mechanisms of THYM.