Photothermal Controlled-Release Immunomodulatory Nanoplatform for Restoring Nerve Structure and Mechanical Nociception in Infectious Diabetic Ulcers

Accurate Delivery of Mesenchymal Stem Cell Spheroids With Platelet-Rich Fibrin Shield: Enhancing Survival and Repair Functions of Sp-MSCs in Diabetic Wound Healing

Diabetic wound is a significant clinical challenge, and stem cell therapy has shown great potential. This study explores the role of mesenchymal stem cell (MSC) spheroids (Sp-MSCs) in healing diabetic wounds and the use of autologous plasma-rich platelet fibrin (PRF) as a scaffold for Sp-MSCs. Through activation of the coagulation system, PRF offers a protective fibrin shield for Sp-MSCs to promote the rapid recovery migration and proliferation of MSCs while maintaining the activity of Sp-MSCs in an inflammatory overload environment by activating the related genes of Integrin-β1-vascular endothelial growth factor (VEGF), and Wnt/β-catenin pathways. The inclusion of Sp-MSCs accelerates the gelation of PRF and results in improved mechanical strength. Additionally, PRF enhances the repair function of Sp-MSCs, creating a favorable microenvironment for angiogenesis. In the wound model of diabetic mice, the combination of PRF with Sp-MSCs accelerates wound healing. Results show that this combination significantly promotes wound repair and regulates the immune microenvironment. The study suggests that PRF is a promising bio-derived scaffold for stem cell applications in diabetic wounds, offering new directions for stem cell therapy and biomimetic scaffold material development.

Hypoxia-Driven Neurovascular Impairment Underlies Structural-Functional Dissociation in Diabetic Sudomotor Dysfunction

Sudomotor dysfunction in diabetic patients increases the risk of fissures, infections, and diabetic foot ulcers (DFUs), thereby reducing the quality of life. Despite its clinical importance, the mechanisms underlying this dysfunction remain inadequately elucidated. This study addresses this gap by demonstrating that despite structural integrity, sweat glands (SGs) in diabetic individuals with DFUs, and a murine model of diabetic neuropathy (DN), exhibit functional impairments, as confirmed by histological and functional assays. Integrated transcriptome and proteome analysis revealed significant upregulation of the SG microenvironment in response to hypoxia, highlighting potential underlying pathways involved. In addition, histological staining and tissue clearing techniques provided evidence of impaired neurovascular networks adjacent to SGs. Single-cell RNA sequencing unveiled intricate intercellular communication networks among endothelial cells (ECs), neural cells (NCs), and sweat gland cells (SGCs), emphasizing intricate cellular interactions within the SG microenvironment. Furthermore, an in vitro SGC-NC interaction model (SNIM) was employed to validate the supportive role of NCs in regulating SGC functions, highlighting the neurovascular-SG axis in diabetic pathophysiology. These findings confirm the hypoxia-driven upregulation of the SG microenvironment and underscore the critical role of the neurovascular-SG axis in diabetic pathophysiology, providing insights into potential therapeutic targets for managing diabetic complications and improving patient outcomes.

IL-33-Induced TREM2+ Macrophages Promote Pathological New Bone Formation Through CREG1-IGF2R Axis in Ankylosing Spondylitis

Pathological new bone formation is the main cause of disability in ankylosing spondylitis (AS), and so far, it lacks a targeted therapy. Macrophages are central orchestrators of inflammation progression and tissue remodeling, but their contribution to pathological new bone formation has largely not been explored. Here, it is identified that TREM2+ macrophages predominated within the sites of new bone formation and adjacent to osteogenic precursor cells. In vivo, both depletion of macrophages and knockout of Trem2 significantly reduced pathological new bone formation in a collagen antibody-induced arthritis (CAIA) model. Specifically, TREM2+ macrophages promoted osteogenic differentiation of ligament-derived progenitor cells (LDPCs) by secreting CREG1, a secretory glycoprotein involved in cell differentiation and normal physiology. CREG1-IGF2R-PI3K-AKT signaling pathway is involved in TREM2+ macrophage-mediated pathological new bone formation. In addition, it is found that IL-33 promoted TREM2+ macrophage differentiation through phosphorylation of STAT6. Targeting the above signalings alleviated new bone formation in the CAIA model. The findings highlight the critical role of IL-33-induced TREM2+ macrophages in pathological new bone formation and provide potential therapeutic targets for halting spinal ankylosis in AS.

Adhesive transparent antimicrobial quaternized chitosan/oxidized dextran/polydopamine nanoparticle hydrogels for accelerated wound healing

Hydrogels possessing appropriate adhesion and antibacterial properties have emerged as promising dressings for expediting wound healing, while also providing the convenience of visualizing the wound site to accurately monitor the healing process. In this study, we incorporated oxidized and degraded polydopamine nanoparticles into quaternized chitosan/oxidized dextran hydrogel QOP series, resulting in enhanced transmittance exceeding 95 % and adhesion strengths reaching up to 19.4 kPa. Moreover, these hydrogels exhibit a well-defined porous structure, rapid gelling ability (<50 s), exceptional self-healing capacity, and a swelling rate surpassing 760 %. Furthermore, the QOP hydrogels demonstrate outstanding hemocompatibility (hemolysis rate < 3 %) and cytocompatibility (cell viability >100 %). In addition, they display potent inhibition against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Staphylococcus pasteuri and Escherichia coli, with bactericidal rates exceeded 90 %. The closure of MRSA-infected wounds along with H&E and Masson staining analysis revealed that QOP hydrogels can expedite wound healing by stimulating collagen deposition and facilitating angiogenesis.

Lauric acid-mediated gelatin/hyaluronic acid composite hydrogel with effective antibacterial and immune regulation for accelerating MRSA-infected diabetic wound healing

The infected diabetic wound healing is an increasingly severe healthcare problem worldwide. Bacterial infection and the inflammatory microenvironment hinder diabetic wound healing. Meanwhile, the combination of inhibiting bacterial growth and promoting macrophage polarization in the wound microenvironment is beneficial for treating diabetic wounds. Nowadays, hydrogels, as an emerging wound dressing, have great potential to replace or supplement traditional bandages or gauze. Here, glycyl methacrylate gelatin (Gel-Gym), oxidized hyaluronic acid (HA-CHO) and lauric acid (LA) were used to prepare the composite hydrogel (GH/LA) in addressing the clinical dilemma. The hydrogel could withstand 50 % compression deformation, its swelling rate was as low as 18 %, and its adhesion to pig skin reached 14 kPa. Moreover, a diabetic infected wound model was used to evaluate the feasibility of GH/LA hydrogel in vivo. The hydrogels' antimicrobial, anti-inflammatory and prorestitutive potentials were further investigated, and GH/LA showed a therapeutic effect on diabetic wounds. Interestingly, macrophage polarization into the M2 phenotype was significantly enhanced in the presence of GH/LA via GPR40/NF-κB pathway. This study provided a new avenue for treating methicillin-resistant staphylococcus aureus (MRSA) infected diabetic wounds.

Scaffold design considerations for peripheral nerve regeneration

Peripheral nerve injury (PNI) represents a serious clinical and public health problem due to its high incurrence and poor spontaneous recovery. Compared to autograft, which is still the best current practice for long-gap peripheral nerve defects in clinics, the use of polymer-based biodegradable nerve guidance conduits (NGCs) has been gaining momentum as an alternative to guide the repair of severe PNI without the need of secondary surgery and donor nerve tissue. However, simple hollow cylindrical tubes can barely outperform autograft in terms of the regenerative efficiency especially in critical sized PNI. With the rapid development of tissue engineering technology and materials science, various functionalized NGCs have emerged to enhance nerve regeneration over the past decades. From the aspect of scaffold design considerations, with a specific focus on biodegradable polymers, this review aims to summarize the recent advances in NGCs by addressing the onerous demands of biomaterial selections, structural designs, and manufacturing techniques that contributes to the biocompatibility, degradation rate, mechanical properties, drug encapsulation and release efficiency, immunomodulation, angiogenesis, and the overall nerve regeneration potential of NGCs. In addition, several commercially available NGCs along with their regulation pathways and clinical applications are compared and discussed. Lastly, we discuss the current challenges and future directions attempting to provide inspiration for the future design of ideal NGCs that can completely cure long-gap peripheral nerve defects.