Electrospun fiber-based immune engineering in regenerative medicine

Molecular signaling pathways in osteoarthritis and biomaterials for cartilage regeneration: a review

Osteoarthritis is a prevalent degenerative joint disease characterized by cartilage degradation, synovial inflammation, and subchondral bone alterations, leading to chronic pain and joint dysfunction. Conventional treatments provide symptomatic relief but fail to halt disease progression. Recent advancements in biomaterials, molecular signaling modulation, and gene-editing technologies offer promising therapeutic strategies. This review explores key molecular pathways implicated in osteoarthritis, including fibroblast growth factor, phosphoinositide 3-kinase/Akt, and bone morphogenetic protein signaling, highlighting their roles in chondrocyte survival, extracellular matrix remodeling, and inflammation. Biomaterial-based interventions such as hydrogels, nanoparticles, and chitosan-based scaffolds have demonstrated potential in enhancing cartilage regeneration and targeted drug delivery. Furthermore, CRISPR/Cas9 gene editing holds promise in modifying osteoarthritis-related genes to restore cartilage integrity. The integration of regenerative biomaterials with precision medicine and molecular therapies represents a novel approach for mitigating osteoarthritis progression. Future research should focus on optimizing biomaterial properties, refining gene-editing efficiency, and developing personalized therapeutic strategies. The convergence of bioengineering and molecular science offers new hope for improving joint function and patient quality of life in osteoarthritis management.

Atoh8 expression inhibition promoted osteogenic differentiation of ADSCs and inhibited cell proliferation in vitro and rat bone defect models

Stem cell-based bone tissue engineering offers a promising approach for treating oral and cranio-maxillofacial bone defects. This study investigated the role of Atoh8, a key regulator in various cells, in the osteogenic potential of adipose-derived stem cells (ADSCs). ADSCs transfected with small interfering RNA (siRNA) targeting Atoh8 were evaluated for proliferation, migration, adhesion, and osteogenic capacity. In vivo, 20 SD rats were used to assess bone regeneration using Atoh8-knockdown ADSC sheets, with new bone formation quantified via micro-CT and histological analysis. Atoh8 knockdown in vitro reduced ADSC proliferation and migration but enhanced osteogenic differentiation and upregulation of osteogenic-related factors. This approach improved bone healing in rat defect models, accelerating repair both in vitro and in vivo. The findings underscore the clinical potential of ADSCs in bone tissue engineering and elucidate Atoh8's regulatory role in ADSC osteogenesis, providing a novel therapeutic strategy for enhancing bone regeneration through targeted modulation of stem cell differentiation pathways.

Icariside II enhances crania defect repair through synergistic angiogenesis and osteogenesis

Vascularized bone tissue engineering for osteogenesis is considered a key approach for the repair of critical bone defects. Icariin(ICA) has been employed in bone tissue engineering for osteogenesis in several studies, demonstrating significant angiogenic and osteogenic effects in vivo in rat models. However, the in vivo angiogenic and osteogenic effects of Icariside II (ICSII), a gastrointestinal metabolite of ICA, remain unclear. Our preliminary study indicated that ICSII upregulated the expression of angiogenic and osteogenic differentiation markers in rat Bone Marrow Mesenchymal Stem Cells(rBMSCs) in vitro. Consequently, we loaded ICA and ICSII onto rBMSCs on Calcium Phosphate Cement(CPC) to construct the complexes CPC/ICA/BMSCs and CPC/ICSII/BMSCs, respectively. Scanning electron microscopy (SEM) revealed that BMSCs exhibited a more favorable morphology for proliferation, adhesion, and spreading on the scaffolds containing ICA and ICSII. Additionally, CPC/ICSII/BMSCs were implanted into a rat bilateral 5-mm critical skull defects model. Micro-CT analysis revealed that the CPC/ICA/BMSCs and CPC/ICSII/BMSCs groups exhibited the most significant promotion of new bone formation and neovascularization. Notably, the CPC/ICSII/BMSCs group demonstrated a significantly stronger neovascularization response than the CPC/ICA/BMSCs group. Histomorphometric analysis further revealed significant collagen fiber, new bone, and neovascularization formation in the CPC/ICA/BMSCs and CPC/ICSII/BMSCs groups, compared to the other groups. Thus, this study concludes that CPC/ICSII/BMSCs, which possess dual osteogenic and angiogenic properties, hold significant potential for repairing critical-size bone defects.

Regulation of mitochondrial apoptosis via siRNA-loaded metallo-alginate hydrogels: A localized and synergistic antitumor therapy

Preventing relapse after resection of a primary tumor continues to be an unmet clinical need. Development of adjuvant biomaterials with the capacity to kill residual cancer cells after tumor resection is of clinical importance. Here we developed a library of metallo-alginate hydrogels containing high concentrations of metallic ions such as Ca2+ in combination with Zn2+, Li+, or Mg2+ to disrupt Ca2+ homeostasis in the mitochondria of cancer cells by local hyperthermia. To synergistically kill tumor cells and suppress the growth of rechallenged tumors, we embedded oncogene-silencing nucleic acids (mTOR siRNA) loaded into polymerc nanoparticles (NPs) composed of poly (β-amino esters) in the metallo-alginate hydrogels, targeting cancer cells that activate multi-drug resistance pathways such PI3K/AKT/mTOR. Metabolomic studies showed alterations in the Warburg effect, mitochondrial transport, and the TCA cycle, confirming cancer cell damage. In vivo studies of this targeted therapy in mice demonstrated a sex-dependent effect. Male B16F10-tumor-bearing mice treated with the synergistic therapy showed restrained tumor growth. In contrast, no therapeutic effect was observed in female counterparts. Our results demonstrate that in situ-formed NP-loaded metallo-alginate hydrogels can modulate two distinct immune signaling networks that are relevant for enhancing cancer cell death. On the basis of our findings, this combination therapy emerges as a promising sex-dependent strategy for clinical translation.

Promoting mitocytosis via gene-engineered aligned fibers for fascia regeneration

The abnormal accumulation of damaged mitochondria severely impedes tissue repair, and conventional therapeutic approaches, such as drug treatments, are often ineffective to remove damaged mitochondria. In this study, we developed gene-engineered aligned electrospun fibers by integrating microfluidic chip technology with a micro-sol oriented electrospinning technique. This study is the first to demonstrate the repair of damaged fascia by promoting mitocytosis through upregulating tetraspanin-9 (TSPAN9). The key gene for mitochondrial exocytosis, TSPAN9, was initially encapsulated into liposomes using microfluidic chip technology. Subsequently, core-shell structured aligned electrospun fibers were fabricated via oriented micro-sol electrospinning, where TSPAN9-loaded liposomes were protected by hyaluronic acid (HA) in the core layer, while aligned polylactic acid (PLA) fibers formed the outer shell layer. In vitro studies revealed that the aligned fibers closely mimicked the oriented structure of fascia tissue and significantly enhanced cell migration by providing directional physical cues. By sustained release of gene-loaded liposomes into cells, mitochondrial homeostasis was effectively restored, mitochondrial respiration was recovered, reactive oxygen species levels were reduced, and mitochondrial membrane potential was maintained. In vivo studies confirmed that these gene-engineered fibers effectively suppressed inflammatory responses and promoted fascia regeneration by facilitating the removal of damaged mitochondria through mitocytosis. In conclusion, gene-engineered fibers developed in this study, which enhance mitocytosis, offer a novel and promising therapeutic strategy for fascia tissue repair.

Inhibiting synovial inflammation and promoting cartilage repair in rheumatoid arthritis using a matrix metalloproteinase-binding hydrogel

Originating from synovial tissue, matrix metalloproteinase-9 (MMP-9) is a key inflammatory factor that promotes the formation and invasion of synovial pannus, leading to cartilage matrix destruction in rheumatoid arthritis (RA). However, clinical trials of systemic use of MMP-9 inhibitors are not successful due to severe side effects. Thus, locally inhibiting MMP-9 may be an alternative in the treatment of RA. Herein, we developed MMP-9 binding peptide-functionalized copper sulfide nanoparticles (CuS-T NPs) and delivered them with light crosslinking chondroitin sulfate methacrylate (ChSMA) hydrogel. We found that the CuS NP-doped hydrogels could inhibit synovial inflammation. Specifically, the CuS-T/ChSMA hydrogel could rapidly bind to MMP-9, thereby inhibiting not only the invasion of RA fibroblast-like synoviocytes but also the polarization of inflammatory M1-type macrophages. The underlying mechanism involved the inhibition of the MAPK pathway. Moreover, ChSMA hydrogel provided a cartilage matrix-mimic microenvironment and synergistically promoted the generation of collagen-2 and aggrecan with CuS NPs. In an adjuvant-induced arthritis mouse model, the intra-articular injection of ChSMA/CuS-T hydrogel significantly alleviated synovial inflammation and accelerated cartilage repair without causing any side effects, killing two birds with one stone in RA therapy.

Bioactive deproteinized bovine bone mineral based on self-assembled albumin nanoparticles promoted bone regeneration via activation of Wnt/β-catenin pathway

One of the major problems faced with pre-implant bone reconstruction therapy is that large bone defects do not heal over time. Artificial bone graft materials, such as deproteinized bovine bone mineral, are commonly used in clinics. However, the lack of osteoinductive capacity and risk of post-implantation infections remain key limitations. Bioactive materials with strong bone formation and a high degree of biocompatibility are still needed. In this study, we synthesised bovine serum albumin nanoparticles (BNP) loaded with Tideglusib (TD), TD and BNP were bound together by self-assembly, and mixed with deproteinized bovine bone mineral (DBBM) to form a bone substitute material (TD-BNP@DBBM) that had low cytotoxicity, promoted cell proliferation and migration, induced cell differentiation, and regulated osteogenesis. In vitro, experiments suggested that TD-BNP@DBBM could promote osteoblast differentiation of MC3T3-E1 cells. In vivo, experiments demonstrated that TD-BNP@DBBM significantly accelerated bone reconstruction and enhanced bone healing in a rat cranial defect model. Furthermore, this result suggested a link between the Wnt/β-catenin pathway and the osteogenic effect, providing a basis for subsequent investigations into the mechanism of bone regeneration induced by osteogenic biomaterials. TD-BNP@DBBM might be a promising new approach for treating bone defects.

A microenvironment responsive nanoparticle regulating osteoclast fate to promote bone repair in osteomyelitis

Osteomyelitis exhibits bone defects in an inflammatory and acid microenvironment. As a crucial factor in this inflammation responses, the macrophage-osteoclast axis is absolutely the core to regulate. The research explored a shell-core structured biomaterial, consisting of a gelatin nanoparticle (GNP) platform loaded with bone morphogenetic protein 9 (BMP9) and coated with a metal phenolic network (TA-Ce), which exhibited adaptive sensitivity to pH values. Extracellularly, it rapidly responded to lower pH, achieving specific release in an inflammatory microenvironment. Intracellularly, it impacted the formation, function, and differentiation of osteoclasts through the macrophage-osteoclast axis, thereby promoting bone defect repair. In vivo and in vitro studies showed GNPs-BMP9@TA-Ce regulated osteoclasts to optimize osteomyelitis treatment strategies, highlighting the potential of modified nanobiomaterials for clinical application.

Glucosamine sulphate endorsed ibuprofen nanocrystals burdened polymeric gel demonstrated multidimensional anti-inflammatory and cartilage protective potential in experimental knee osteoarthritis: In vitro and in vivo studies

Osteoarthritis (OA) is a chronic degenerative musculoskeletal condition associated with progressive loss of hyaline cartilage, subchondral bone remodelling, and inflammation. Despite ongoing research, no United States Food and Drug administration (USFDA) approved drugs for OA are available. The current investigation explores the potential of glucosamine sulphate endorsed ibuprofen nanocrystals loaded polymeric gel (IBU-GS-NCs gel) for its anti-inflammatory and disease-modifying capabilities in the osteoarthritic rat model. IBU-GS-NCs were engineered by using the anti-solvent precipitation method that later exhibited particle size 34.57 ± 0.79 nm, zeta (ζ) potential -2.81 ± 0.6 mV, and drug content 7.05 ± 0.19 %. On the other hand, IBU-GS-NCs gel demonstrated 0.507 ± 0.029 % drug loading with spreadability and viscosity close to marketed diclofenac emulgel. Next, the amount of IBU infused through the rat skin in ex vivo permeation study from IBU-GS-NCs gel and IBU gel was calculated to be 479.59 ± 6.28 µg/cm2 and 255.91 ± 4.44 µg/cm2, respectively after 24 h with 1.87-fold increment. Steady-state flux and permeability coefficient for IBU-GS-NCs gel through rat skin were 31.70 ± 0.11 µg/cm2h and 63.41 ± 0.23×10-3 cm/h, respectively. In contrast to the positive control, the representative radiograph for IBU-GS-NCs gel-treated osteoarthritic rats indicated regeneration of articular cartilage with the absence of osteophytes. Histological evaluation of IBU-GS-NCs gel illustrated marked recovery in articulate cartilage thickness as well as glycosaminoglycan (GAG) level. Western blot analysis for synovial tissue of positive control displayed a 9.01, 2.66, 2.51 and 5.75-fold increase in COX-2, TNF-α, and IL-1β, Col2a1 respectively as compared to normal control. In contrast, IBU-GS-NCs gel-treated rats demonstrated 6.28, 4.06, 2.81 and 5.54-fold reduction in COX-2, TNF-α, IL-1β, and Col2a1 respectively compared to positive control. These findings advocate for improved anti-inflammatory and cartilage protective potential of IBU-GS-NCs gel. In conclusion, IBU-GS-NCs gel may be a potential candidate for translating into a clinically viable product to offer effective treatment for knee OA.

ZIF-8 composite nanofibrous membranes loaded with bFGF: a new approach for tendon adhesion prevention and repair

During tendon injury repair, deficiency of basic fibroblast growth factor (bFGF) is a critical factor leading to unsatisfactory repair results. This study aims to prepare bFGF-loaded zeolite imidazole framework-8 (ZIF-8) nanocrystals using a one-pot synthesis method. Subsequently, a bilayer nanofibrous membrane incorporating these drug-loaded nanocrystals was fabricated through electrospinning technology. The potential of this composite nanofibrous membrane to facilitate the continuous release of bFGF at the site of tendon injury was evaluated, with the aim of enhancing the quality of tendon repair. The efficacy of the nanofibrous membrane in promoting tendon differentiation, preventing tendon adhesion, and facilitating tendon repair was assessed through both in vitro and in vivo experiments. At the site of tendon injury, the degradation of ZIF-8 in an acidic microenvironment resulted in the release of bFGF and Zn2+, which contributed to the enhancement of tendon repair. ZIF-8 nanocrystals achieved an encapsulation efficiency of 50.13% ± 1.42%. Following a continuous release period exceeding 40 days, the cumulative in vitro release rate was determined to be 35.02% ± 4.27%. The incorporation of ZIF-8 nanocrystals into a nanofibrous membrane demonstrated the ability to effectively preserve the bioactivity of bFGF while enabling sustained release at the site of tendon injury, thereby facilitating tendon repair. The findings offer novel insights into the treatment of tendon injuries and provide significant theoretical guidance for the tendon repair process.

Polyphenol-Mediated Electroactive Hydrogel with Armored Exosomes Delivery for Bone Regeneration

Prolonged oxidative stress and reduced activity of mesenchymal stem cells are significant barriers to effective bone repair. Current therapeutic approaches often suffer from limited long-term efficacy due to inefficient exosome delivery and the degradation of biological materials. Here, we present an electroactive gelatin methacryloyl hydrogel incorporating a tannic acid-mediated conductive polypyrrole microfiber network and exosomes armored with a metal-polyphenol network, designed to mitigate chronic inflammation and enhance bone healing. The iron-tannic acid complex forms a protective coating on the surface of exosomes, shielding them from damage in inflammatory environments and promoting osteoblast differentiation. This is achieved by enabling exosomes to evade lysosomal degradation through the proton sponge effect. Additionally, the phenolic hydroxyl groups of tannic acid effectively scavenge reactive oxygen species at injury sites. By delivering electrical stimulation to mimic the native electrophysiological environment, the catechol-quinone redox balance is maintained, providing sustained antioxidant effects. In a rat bone defect model, this multifunctional hydrogel demonstrated robust activity for bone regeneration. These findings demonstrated the ability of this electroactive hydrogel system to enhance exosome delivery, provide long-term antioxidative activity, and promote osteogenic differentiation, offering a promising therapeutic platform for bone tissue engineering.

Naringin Mitigates Chondrocyte Apoptosis in Osteoarthritis by Suppressing the miR-29a-3p-Bax Pathway

The present study aims to explore potential therapeutic effects of Naringin on osteoarthritis (OA) and investigate the underlying mechanism. The chondrocytes in the joint usually undergo detrimental changes during OA progression, including increased apoptosis. miRNAs emerge as crucial regulators in this processes. The study delves into the intricate interplay between miR-29a-3p, BAX-mediated apoptosis, and Naringin intervention. Pro-inflammatory cytokines induce chondrocyte apoptosis in OA, impacting cell viability. Naringin treatment effectively restores cell survivability (1.8-fold change), inhibiting caspase activity (0.54-fold change) and lowering matrix metalloproteinases-9 (MMP-9) (0.50-fold change) and MMP-13 expression (0.50-fold change). Furthermore, COL2A1, Sox9, Runx2, TGF-β1, and BMP-4 levels in cytokines-stimulated chondrocytes were enhanced by Naringin, accompanied by decreased productions of MMP3 and MMP13. In cartilage tissues of OA rats, Osteoarthritis Research Society International (OARSI) scores in Safranin O staining were elevated, Pro-inflammatory cytokine productions and MMP3 and MMP13 expressions were enhanced, and COL2A1, Sox9, Runx2, TGF-β1, and BMP-4 levels were reduced, which were remarkably rescued by Naringin. We further revealed the intricate connection between miR-29a-3p and the chondrocyte fate. Elevated miR-29a-3p expression corresponds to increased apoptotic chondrocytes. Naringin suppresses miR-29a-3p, curbing apoptosis and suggesting a potential therapeutic avenue. Notably, BAX emerges as a key player, with miR-29a-3p influencing its expression. Naringin's mitigation of BAX upregulation underscores its protective role. Overall, we found the potential role of Naringin in addressing chondrocyte apoptosis in OA through miR-29a-3p-BAX modulation, offering insights into innovative OA management strategies.

Biomimetic Microstructured Scaffold with Release of Re-Modified Teriparatide for Osteoporotic Tendon-to-Bone Regeneration via Balancing Bone Homeostasis

Osteoporotic tendon-to-bone interface healing is challenging, with a high surgical repair failure rate of up to 68%. Conventional tissue engineering approaches have primarily focused on promoting interface healing by stimulating regeneration in either the tendon or bone. However, these methods often fall short of achieving optimal therapeutic outcomes due to their neglect of balancing bone homeostasis and remodeling the microstructure at the osteoporotic tendon-to-bone interface. Herein, a series of site-specific functional modifications are carried out on teriparatide to develop recombinant human parathyroid hormone (R-PTH). A biomimetic microstructured reconstruction scaffold (BMRP) is constructed using a decalcified mussel shell scaffold, pre-gel, and R-PTH. The BMRP mimics the microstructures of the native tendon-to-bone interface and restores the original structure of the interface tissue by repairing injured cells, balancing bone homeostasis, and remodeling the microstructure of the osteoporotic tendon-to-bone interface. In an osteoporotic rotator cuff tear model, BMRP is in situ implanted at the injured site, resulting in structural reconstruction and functional recovery. The BMRP demonstrates excellent repair effects, representing a novel therapeutical alternative for treating osteoporotic tendon-to-bone injury potential for clinical application.

Anisotropic structure of nanofiber hydrogel accelerates diabetic wound healing via triadic synergy of immune-angiogenic-neurogenic microenvironments

Wound healing in chronic diabetic patients remains challenging due to the multiple types of cellular dysfunction and the impairment of multidimensional microenvironments. The physical signals of structural anisotropy offer significant potential for orchestrating multicellular regulation through physical contact and cellular mechanosensing pathways, irrespective of cell type. In this study, we developed a highly oriented anisotropic nanofiber hydrogel designed to provide directional guidance for cellular extension and cytoskeletal organization, thereby achieving pronounced multicellular modulation, including shape-induced polarization of macrophages, morphogenetic maturation of Schwann cells, oriented extracellular matrix (ECM) deposition by fibroblasts, and enhanced vascularization by endothelial cells. Additionally, we incorporated a VEGF-mimicking peptide to further reinforce angiogenesis, a pivotal phase that interlocks with immune regulation, neurogenesis, and tissue regeneration, ultimately contributing to optimized inter-microenvironmental crosstalk. In vivo studies validated that the anisotropic bioactive nanofiber hydrogel effectively accelerated diabetic wound healing by harnessing the triadic synergy of the immune-angiogenic-neurogenic microenvironments. Our findings highlight the promising potential of combining physical and bioactive signals for the modulation of various cell types and the refinement of the multidimensional microenvironment, offering a novel strategy for diabetic wound healing.

Vascular endothelial growth factor (VEGF) and endogenous calcium-capturing gelatin methacrylate hydrogels promote bone tissue regeneration

The regeneration of irregular-shaped bone defects remains a perpetuating challenge. Scaffolds with osteogenesis and angiogenesis dual capabilities hold considerable promise for bone tissue repair. The objective of this study was to delineate the synergistic effect of calcium ions (Ca2+)-recruiting peptide (FVDVT, abbreviated as CP) and vascular endothelial growth factor (VEGF)-binding prominin-1-derived peptide (DRVQRQTTTVVA, abbreviated as BP) in gelatin methacrylate (GM)-based hydrogels (GM@BCP). BP-loaded hydrogels can recruit VEGF in situ to promote angiogenesis, as well as promote cell viability and growth as revealed by the whole transcriptome RNA sequencing of human umbilical vein endothelial cells (HUVECs). PLA/G@CP short fibers can induce bone matrix mineralization and regulate mechanical behavior of hydrogels. The GM@BCP hydrogels were found to be cytocompatible, non-toxic, and bioresorbable, as well as fill an irregular-shaped bone defect in vivo. Moreover, evaluation in a rat calverial defect model manifested significant promise of GM@BCP hydrogels to promote bone tissue repair by simultaneously inducing osteogenesis and angiogenesis 8 weeks post-operatively. Taken together, our approach of simultaneously harnessing in situ calcium ion (Ca2+) binding and VEGF recruitment may have broad implications for fracture repair and potentially other related disciplines.

Exudate Management, Facile Detachment, and Immunometabolism Regulation for Wound Healing Using Breathable Dressings

Developing breathable dressings with multifunctional properties (such as exudate management, easy removal, and immunometabolism regulation) presents significant challenges in wound healing. This study employs the Hofmeister effect to prepare a sodium citrate-cross-linked cryogel (CA-CS) with versatile functions, including porous and loose structures, rapid shape recovery ability, superior fatigue resistance behavior, and outstanding biocompatibility capabilities. The CA-CS cryogels demonstrated strong anti-inflammatory properties by reversing the lipopolysaccharides-induced M1 macrophages and increasing M2 macrophage percentages in vitro. Additionally, these breathable CA-CS cryogels exhibited superior hemostatic activity in vivo. The easily detachable CA-CS cryogels enhanced nutrient exchange, promoted exudate absorption, regulated immune response, and induced metabolic reprogramming, thereby supporting skin regeneration and hair follicle formation in a full-thickness skin defect mouse model. We expect that these CA-CS cryogels will drive the development of next-generation dressings for effective wound regeneration in clinical practice.

Injectable DMM/GelMA hydrogel for diabetic wound healing via regulating mitochondrial metabolism and macrophage repolarization

The chronic diabetic wounds represented by diabetes foot ulcers (DFUs) are a worldwide challenge. Excessive production of reactive oxygen species (ROS) and persistent inflammation caused by the impaired phenotype switch of macrophages from M1 to M2 during wound healing are the main culprits of non-healing diabetic wounds. Therefore, an injectable DMM/GelMA hydrogel as a promising wound dressing was designed to regulate the mitochondrial metabolism of macrophages via inhibiting succinate dehydrogenase (SDH) activity and to promote macrophage repolarization towards M2 type. DMM/GelMA hydrogel exhibited good biocompatibility, injectability and water absorption and retention capacity. In vitro studies showed that DMM/GelMA hydrogel inhibited SDH activity, recovered the decrease in mitochondrial membrane potential, and significantly reduced the production of ROS and inflammatory cytokines in the LPS-evoked macrophages. In vivo evaluations and RNA sequencing analysis demonstrated that DMM/GelMA hydrogel downregulated ROS generation, the ratio of M1/M2 macrophages and pro-inflammatory cytokine production in the full-thickness skin wound model in the diabetic mice. Additionally, DMM/GelMA hydrogel improved the wound-healing quality with thicker epidermis, more collagen deposition and higher ratio of collagen I/III by sustained release of DMM. These findings indicate this hydrogel has a great potential to be a biocompatible, injectable and anti-inflammatory dressing for better diabetic wound healing.

Dual functional hydrogel of osteoclastic-inhibition and osteogenic-stimulation for osteoporotic bone defect regeneration

Osteoporotic bone regeneration poses significant challenges due to the complexity of the condition. Osteoporosis, a degenerative disorder, results from an imbalance in bone homeostasis driven by dysregulation of osteoblast and osteoclast activity. This complicates the treatment of osteoporosis and its related bone injuries in clinical practice. Despite the development of various polymer scaffolds for bone defect repair, achieving effective regeneration in osteoporotic bones-especially when combined with osteoporosis medications-remains difficult. In this study, we designed a drug delivery system composed of mesoporous bioactive glass (MBG) and photo-crosslinked hyaluronic acid methacrylate (HAMA). This system, loaded with the osteogenesis-promoting peptide DWIVA (D5) and the osteoclastogenesis-inhibiting drug alendronate (ALN), is gelled using a light initiator and 405 nm wavelength light. The MBG@D5-Gel complex enables the controlled spatiotemporal release of these agents, markedly enhancing bone regeneration in osteoporotic conditions within ovariectomized rats by inhibiting osteoclastogenesis and bone resorption while promoting osteogenic differentiation and mineralization. This dual-action system synergistically regulates osteoblast and osteoclast activity, optimizing the pathological microenvironment of osteoporosis and facilitating the repair of osteoporotic bone defects. MBG@D5-Gel holds great potential as an effective organic-inorganic hybrid biomimetic implant material for the treatment of osteoporotic bone defects.

Advancing Chronic Wound Healing through Electrical Stimulation and Adipose-Derived Stem Cells

Chronic cutaneous wounds are a major clinical challenge worldwide due to delayed healing, recurrent infections, and resistance to conventional therapies. Adipose-derived stem cells (ASCs) have shown promise as a cell-based therapy, but their therapeutic efficacy is often compromised by the harsh microenvironment of chronic wounds. Recent advances in bioengineering, particularly the application of electrical stimulation (ES), offer an innovative approach to enhancing the regenerative properties of ASCs. By restoring the natural electrical current in the wound, ES provides a strong stimulus to the cells involved in healing, thereby accelerating the overall wound-healing process. Recent studies show that ASCs can be significantly activated by ES, which increases their viability, proliferation, migration, and secretory capacity, all of which are crucial for the proper healing of chronic wounds. This review examines the synergistic effects of ES and ASCs on wound healing, focusing on the biological mechanisms involved. The review also highlights novel self-powered systems and other emerging technologies such as advanced conductive materials and devices that promise to improve the clinical translation of ES-based treatments. By summarizing the current state of knowledge, this review aims to provide a framework for future research and clinical application of ES and ASCs in wound care.

Intermittent hypoxic stimulation promotes efficient expression of Hypoxia-inducible factor-1α and exerts a chondroprotective effect in an animal osteoarthritis model

Hypoxia-inducible factor-1α plays an important role in the homeostasis of articular cartilage in hypoxic environments. Therefore, modulation of hypoxia-inducible factor-1α by regulating the oxygen environment could be a useful treatment for osteoarthritis. This study aimed to assess the chondroprotective effects of intermittent hypoxia on cultured chondrocytes and an animal model of osteoarthritis. In vitro, human chondrocytes were exposed to 2 h of hypoxic stimulation three times at 1-h intervals, and protein and gene expression of hypoxia-inducible factor-1α, ACAN, and cell viability was measured over time. In vivo, 8-week-old male Wistar rats were injected with monosodium iodoacetate to induce osteoarthritis and then reared in 12% hypoxia for 24 h, followed by 24 h in steady oxygen, repeated alternately for a total of 28 days. A histological analysis was performed on days 8 and 28. In the intermittent hypoxia group, each protein expression increased with each repeated hypoxic stimulation to human chondrocytes; finally, the protein level was significantly higher with intermittent hypoxia than with continuous hypoxic stimulation, cell viability was increased, and gene expression was not significantly increased. In the osteoarthritis animal model, for 8 days, there were stronger hypoxia-inducible factor-1α staining and no significant differences in articular cartilage destruction. Furthermore, for 28 days, there was significantly less articular cartilage destruction in the rat osteoarthritis model with intermittent hypoxia than with steady oxygen rearing. Intermittent hypoxia increased cartilage metabolism by increasing hypoxia-inducible factor-1α proteins in articular chondrocytes, which may be effective in preventing articular cartilage degeneration in a rat osteoarthritis model.

The causal relationship of inflammation-related factors with osteoporosis: A Mendelian Randomization Analysis

BACKGROUND

We used Mendelian randomization (MR) approach to examine whether genetically determined inflammation-related risk factors play a role in the onset of osteoporosis (OP) in the European population.

METHODS

Genome-wide association studies (GWASs) summary statistics of estimated bone mineral density (eBMD) obtained from the public database GEnetic Factors for OSteoporosis Consortium (GEFOS) including 142,487 European people. For exposures, we utilized GWAS data of 9 risk factors including diseases chronic kidney disease (CKD) (41,395 cases and 439,303 controls), type 2 diabetes (T2D) (88,427 cases and 566,778 controls), Alzheimer's disease (AD) (71,880 cases, 383,378 controls) and major depression disorder (MDD) (9240 cases and 9519 controls) and lifestyle behaviors are from different consortiums. Inverse variance weighted (IVW) analysis was principal method in this study and random effect model was applied; MR-Egger method and weighted median method were also performed for reliable results. Cochran's Q test and MR-Egger regression were used to detect heterogeneity and pleiotropy and leave-one-out analysis was performed to find out whether there are influential SNPs.

RESULTS

We found that T2D (IVW: β = 0.05, P = 0.0014), FI (IVW: β = -0.22, P < 0.001), CKD (IVW: β = 0.02, P = 0.009), ALZ (IVW: β = 0.06, P = 0.005), Coffee consumption (IVW: β = 0.11, P = 0.003) were causally associated with OP (P<0.006after Bonferroni correction).

CONCLUSIONS

Our study revealed that T2D, FI, CKD, ALZ and coffee consumption are causally associated with OP. Future interventions targeting factors above could provide new clinical strategies for the personalized prevention and treatment of osteoporosis.

An anti-inflammatory and anti-fibrotic Janus hydrogel for preventing postoperative peritoneal adhesion

Postoperative peritoneal adhesion (PPA) is pathological tissue hyperplasia between surgical wounds and nearby organs. Currently, traditional double-sided bioadhesives are limited in preventing PPA due to the indiscriminate adhesive properties and the poor interaction with wet tissues. Herein, we developed a Janus hydrogel, named PAA-Cos, by using the polycationic carbohydrate polymer of chitooligosaccharide (Cos) and the polyanionic polymer of polyacrylic acid (PAA). The adhesive layer of Janus hydrogels could adhere to wet tissue tightly due to surfaces composed of carboxyls, and the positively charged biomaterial (Cos) neutralized carboxyls on one side of PAA hydrogel to form Janus hydrogels. Moreover, PAA-Cos can further load with ligustrazine hydrochloride (Ligu), a pharmaceutical compound with anti-inflammatory and anti-fibrotic effects, finally obtaining PAA-Cos@Ligu. After the application of PAA-Cos@Ligu on the surgical trauma, the bottom surface can adhere to wet tissues robustly to restore the wound, while the top surface acts as a physical barrier with antiadhesive effects to avoid PPA. PAA-Cos@Ligu also exhibited anti-inflammatory effects by promoting M2 macrophage polarization, inhibiting the myofibroblast-like differentiation of peritoneal mesothelial cells, and blocking the TGF-β/Smad2/3 signaling pathway to hinder collagen deposition. Our findings suggest that PAA-Cos@Ligu has great potential as an anti-adhesion candidate with biocompatibility and ease of preparation.

Preparation of hydrogel microsphere and its application in articular cartilage injury

In recent years, hydrogel microspheres have garnered significant attention due to their unique structure and functionality, demonstrating substantial potential in articular cartilage injury repair. This paper provides a comprehensive overview of current strategies for cartilage injury repair and summarizes the materials and preparation methods of hydrogel microspheres. Furthermore, it highlights the multiple roles of hydrogel microspheres in cartilage repair, including inflammation control, regulation of chondrocyte metabolism, drug and cell delivery, lubrication improvement, and recruitment of endogenous stem cells. Finally, the paper discusses the application prospects of hydrogel microspheres, identifies current limitations and challenges, and offers insights to guide future research and practical applications in cartilage injury repair.

Biological Augmentation Using Electrospun Constructs with Dual Growth Factor Release for Rotator Cuff Repair

Surgical reattachment of tendon to bone is the standard therapy for rotator cuff tear (RCT), but its effectiveness is compromised by retear rates of up to 94%, primarily due to challenges in achieving successful tendon-bone enthesis regeneration under natural conditions. Biological augmentation using biomaterials has emerged as a promising approach to address this challenge. In this study, a bilayer construct incorporates polydopamine (PDA)-mediated bone morphogenetic protein 2 (BMP2) and BMP12 in separate poly(lactic-co-glycolic acid) (PLGA) fiber layers to promote osteoblast and tenocyte growth, respectively, and intermediate fibrocartilage formation, aiming to enhance the regenerative potential of tendon-bone interfaces. The lower layer, consisting of PLGA fibers with BMP2 immobilization through PDA adsorption, significantly accelerated osteoblast growth. Concurrently, the upper BMP12@PLGA-PDA fiber mat facilitated fibrocartilage formation and tendon tissue regeneration, evidenced by significantly elevated tenocyte viability and tenogenic differentiation markers. Therapeutic efficacy assessed through in vivo RCT models demonstrated that the dual-BMP construct augmentation significantly promoted the healing of tendon-bone interfaces, confirmed by biomechanical testing, cartilage immunohistochemistry analysis, and collagen I/II immunohistochemistry analysis. Overall, this combinational strategy, which combines augmentation patches with the controlled release of dual growth factors, shows great promise in improving the overall success rates of rotator cuff repairs.

Boosting mRNA-Engineered Monocytes via Prodrug-Like Microspheres for Bone Microenvironment Multi-Phase Remodeling

Monocytes, as progenitors of macrophages and osteoclasts, play critical roles in various stages of bone repair, necessitating phase-specific regulatory mechanisms. Here, icariin (ICA) prodrug-like microspheres (ICA@GM) are developed, as lipid nanoparticle (LNP) transfection boosters, to construct mRNA-engineered monocytes for remodeling the bone microenvironment across multiple stages, including the acute inflammatory and repair phases. Initially, ICA@GM is prepared from ICA-conjugated gelatin methacryloyl via a microfluidics system. Then, monocyte-targeting IL-4 mRNA-LNPs are then prepared and integrated into injectable microspheres (mRNA-ICA@GM) via electrostatic and hydrogen bond interactions. After bone-defect injection, LNPs are controlled released from mRNA-ICA@GM within 3 days, rapidly transfecting monocytes for monocyte IL-4 mRNA-engineering, which effectively suppressed acute inflammatory responses via polarization programming and paracrine signaling. Afterwards, ICA is sustainably released as well via cleavable boronate esters across multiple stages, cooperatively boosting the mRNA-engineered monocytes to inhibit coenocytic fusion and osteoclastic function. Both in vitro and in vivo data indicated that mRNA-ICA@GM can not only reverse the inflammatory environment but also suppress monocyte-derived osteoclast formation to accelerate bone repair. In summary, mRNA-engineered monocytes and ICA prodrug-like microspheres are combined to achieve long-lasting multi-stage bone microenvironment regulation, offering a promising repair strategy.

Inhibiting Friction-Induced Exogenous Adhesion via Robust Lubricative Core-Shell Nanofibers for High-Quality Tendon Repair

Friction is the trigger cause for excessive exogenous adhesion, leading to the poor self-repair of the tendon. To address this problem, we developed electrospun dual-functional nanofibers with surface robust superlubricated performance and bioactive agent delivery to regulate healing balance by reducing exogenous adhesion and promoting endogenous healing. Coaxial electrospinning and our previous developed in situ robust nanocoating growth techniques were employed to create the lubricative/repairable core-shell structured nanofibrous membrane (L/R-NM). The L/R-NM shell featured a robust coating of the zwitterionic PMPC polymer for strong hydration lubrication to resist exogenous healing. The core could achieve sustained platelet-rich plasma release to promote endogenous healing. Friction tests and cell experiments confirmed L/R-NM's prominent lubricating properties and antiadhesive performance in vitro. Rat tendon injury model evaluation indicated that L/R-NM effectively promotes high-quality tendon repair by inhibiting friction-induced exogenous adhesion and promoting endogenous healing. Therefore, we believe that L/R-NM will open a unique novel horizon for tendon repair.

Nanomaterial-functionalized electrospun scaffolds for tissue engineering

Tissue engineering has emerged as a biological alternative aimed at sustaining, rehabilitating, or enhancing the functionality of tissues that have experienced partial or complete loss of their operational capabilities. The distinctive characteristics of electrospun nanofibrous structures, such as their elevated surface-area-to-volume ratio, specific pore sizes, and fine fiber diameters, make them suitable as effective scaffolds in tissue engineering, capable of mimicking the functions of the targeted tissue. However, electrospun nanofibers, whether derived from natural or synthetic polymers or their combinations, often fall short of replicating the multifunctional attributes of the extracellular matrix (ECM). To address this, nanomaterials (NMs) are integrated into the electrospun polymeric matrix through various functionalization techniques to enhance their multifunctional properties. Incorporation of NMs into electrospun nanofibrous scaffolds imparts unique features, including a high surface area, superior mechanical properties, compositional variety, structural adaptability, exceptional porosity, and enhanced capabilities for promoting cell migration and proliferation. This review provides a comprehensive overview of the various types of NMs, the methodologies used for their integration into electrospun nanofibrous scaffolds, and the recent advancements in NM-functionalized electrospun nanofibrous scaffolds aimed at regenerating bone, cardiac, cartilage, nerve, and vascular tissues. Moreover, the main challenges, limitations, and prospects in electrospun nanofibrous scaffolds are elaborated.

Slide-Ring Structured Stress-Electric Coupling Hydrogel Microspheres for Low-Loss Transduction Between Tissues

High transductive loss at tissue injury sites impedes repair. The high dissipation characteristics in the electromechanical conversion of piezoelectric biomaterials pose a challenge. Therefore, supramolecular engineering and microfluidic technology is utilized to introduce slide-ring polyrotaxane and conductive polypyrrole to construct stress-electric coupling hydrogel microspheres. The molecular slippage mechanism of slide-ring structure stores and releases mechanical energy, reducing mechanical loss, the piezoelectric barium titanate enables stress-electricity conversion, and conjugated π-electron movement in conductive network improves the internal electron transfer efficiency of microspheres, thereby reducing the loss in stress-electricity conversion for the first time. Compared to traditional piezoelectric hydrogel microspheres, the stress-electric coupling efficiency of low-dissipation microspheres increased by 2.3 times, and the energy dissipation decreased to 43%. At cellular level, electrical signals generated by the microspheres triggered Ca2+ influx into stem cells and upregulated the cAMP signaling pathways, promoting chondrogenic differentiation. Enhanced electrical signals induced macrophage polarization to the M2 phenotype, reshaping inflammation and promoting tissue repair. In vivo, the low-dissipation microspheres restored low-loss transduction between tissues, alleviated cartilage damage, improved behavioral outcomes, and promoted the treatment of osteoarthritis in rats. Therefore, this study proposes a new strategy for restoring low-loss transduction between tissues, particularly in mechanically sensitive tissues.

The immunoglobulin of yolk and cerium oxide-based fibrous poly(L-lactide-co-glycolide)/gelatin dressings enable skin regeneration in an infectious wound model

The bacterial infection and oxidative wound microenvironment delay skin repair and necessitate intelligent wound dressings to enable scarless wound healing. The immunoglobulin of yolk (IgY) exhibits immunotherapeutic potential for the potential treatment of antimicrobial-resistant pathogens, while cerium oxide nanoparticles (CeO2 NPs) could scavenge superoxide dismutase (SOD) and inflammation. The overarching objective of this study was to incorporate IgY and CeO2 NPs into poly(L-lactide-co-glycolide)/gelatin (PLGA/Gel)-based dressings (P/G@IYCe) for infected skin repair. The P/G@IYCe manifested good biocompatibility as well as showed significant antibacterial effect against Staphylococcus aureus (S. aureus) and Escherichia coli (E.coil) in vitro. Subcutaneous implantation of membranes in rats exhibited cytocompatibility. Transplantation of membranes in S. aureus-infected full-thickness excisional defects manifested significant beneficial effect of P/G@IYCe dressings than that of the other groups in terms of the scar tissue formation, inflammation resolution, and scavenging of reactive oxygen species (ROS) at 2 weeks post-transplantation. Taken together, the dual delivery of IgY and CeO2 may enable intelligent wound dressings.

Material-driven immunomodulation and ECM remodeling reverse pulmonary fibrosis by local delivery of stem cell-laden microcapsules

Recent progress in stem cell therapy has demonstrated the therapeutic potential of intravenous stem cell infusions for treating the life-threatening lung disease of pulmonary fibrosis (PF). However, it is confronted with limitations, such as a lack of control over cellular function and rapid clearance by the host after implantation. In this study, we developed an innovative PF therapy through tracheal administration of microfluidic-templated stem cell-laden microcapsules, which effectively reversed the progression of inflammation and fibrotic injury. Our findings highlight that hydrogel microencapsulation can enhance the persistence of donor mesenchymal stem cells (MSCs) in the host while driving MSCs to substantially augment their therapeutic functions, including immunoregulation and matrix metalloproteinase (MMP)-mediated extracellular matrix (ECM) remodeling. We revealed that microencapsulation activates the MAPK signaling pathway in MSCs to increase MMP expression, thereby degrading overexpressed collagen accumulated in fibrotic lungs. Our research demonstrates the potential of hydrogel microcapsules to enhance the therapeutic efficacy of MSCs through cell-material interactions, presenting a promising yet straightforward strategy for designing advanced stem cell therapies for fibrotic diseases.

Gelatin/Poly (Lactic-Co-Glycolic Acid)/Attapulgite Composite Scaffold Equipped with Teriparatide Microspheres for Osteogenesis in vitro and in vivo

Background

Given the risks associated with autologous bone transplantation and the limitations of allogeneic bone transplantation, scaffolds in bone tissue engineering that incorporate bioactive peptides are highly recommended. Teriparatide (TPTD) plays a significant role in bone defect repair, although achieving controlled release of TPTD within a bone tissue engineering scaffold remains challenging. This work reports a new approach for treatment of teriparatide using a water-in-oil-in-water (w/o/w) microspheres be equipped on gelatin (GEL)/Poly lactic-glycolic acid (PLGA)/attapulgite (ATP) scaffold.

Methods

In this study, TPTD microspheres were prepared by the water-in-oil-in-water (w/o/w) double emulsion technique and GEL/PLGA/ATP composite scaffolds with different setups were prepared by salt leaching method. Both microspheres and scaffolds underwent physicochemical characterization. Mouse bone mesenchymal stem cells (BMSCs) were co-cultured with extracts from the microspheres and scaffolds to evaluate cell proliferation and osteogenesis. Four weeks post-implantation, the effectiveness of the scaffolds containing microspheres for repairing skull defects in mice was assessed.

Results

Both TPTD microspheres and the GEL/PLGA/ATP scaffold significantly enhanced the proliferation and osteogenic differentiation of BMSCs. Markers of osteoblast activity, including COL1, RUNX2, OCN, and OPN, were markedly up-regulated. Further, micro-CT, histological, and immunohistochemical analyses revealed extensive new bone formation on the scaffold.

Conclusion

The GEL/PLGA/ATP composite scaffold, equipped with TPTD microspheres, demonstrates significant potential for use in bone tissue engineering, providing an effective option for bone regeneration and repair in clinical applications.

SIGLEC11 promotes M2 macrophage polarization through AKT-mTOR signaling and facilitates the progression of gastric cancer

BACKGROUND

Sialic acid-binding immunoglobulin-like lectins (SIGLECs) are widely expressed on immune cell surfaces, play an important role in maintaining immune homeostasis and regulating inflammatory responses, and are increasingly emerging as potential targets for tumor immunotherapy. However, the expression profile and crucial role of SIGLEC11 in gastric cancer (GC) remain unclear. This study aimed to elucidate the prognostic relevance of SIGLEC11 expression and its role in the immune microenvironment in patients with GC.

METHODS

SIGLEC11 expression profile was analyzed using bioinformatics, immunohistochemistry, and immunofluorescence staining. Flow cytometry, mouse tumor models, patient-derived tumor organoid models, and RNA sequencing were used to explore the potential functions with the underlying mechanisms of SIGLEC11 in a coculture system of macrophages and GC cells.

RESULTS

We demonstrated that SIGLEC11 was predominantly expressed in normal tissues. However, tumor-infiltrating SIGLEC11+ cells in the high SIGLEC11 expression subgroups showed poor overall survival, which was associated with the expression of an immunosuppressive regulator. Our results showed that SIGLEC11 was predominantly expressed in monocytes and macrophages and selectively upregulated in tumor-associated macrophages. Furthermore, SIGLEC11 promoted macrophage M2 polarization via AKT-mTOR signaling. In addition, SIGLEC11+ macrophages accelerate GC progression.

CONCLUSIONS

The abundance of SIGLEC11+ M2-like macrophage-infiltrating tumors may serve as a biomarker for identifying immunosuppressive subtypes of GC. Thus, the potential role of SIGLEC11+ M2 macrophages as therapeutic targets warrants further investigation.

Directed Cell Growth of C2C12 Cells on ECM Free Bioprinted Nano/Micro Scaffolds

Skeletal muscle cell growth impairment can result in severe health issues, such as reduced mobility, metabolic problems, and cardiovascular issues, which can significantly impact an individual's overall health and lifestyle. To address this issue, it is essential to adopt a multi-faceted approach. Conventional 2D cell culture methods fail to replicate the critical features of in vivo micro/nanoarchitecture, which is crucial for the growth of skeletal muscle cells. In this study, the directed growth of mouse skeletal myoblasts (C2C12) cells on ECM-free biocompatible scaffolds is demonstrated and fabricated using two-photon lithography (TPL). These scaffolds are 2D and 3D and have nano/micro-features derived from chitosan-based carbon quantum dots (Ch-CQDs). Ch-CQDs act as two-photon initiators for TPL and also provide the scaffolds with adequate mechanical strength and specific binding sites. These scaffolds are biocompatible and can support cellular adhesion and growth without the need for ECM coating. The nano/micro scaffolds mimic the in vivo cellular microenvironment, enabling directed cell growth on ECM-free surfaces. The fabricated scaffolds have tunable mechanical strength ranging from 0.09 to 0.75 GPa. By using Ch-CQDs, scaffolds are created that promote cell growth and alignment, which is crucial for skeletal muscle cell growth.

Functional Mechanism and Clinical Implications of lncRNA LINC-PINT in Delayed Fracture Healing

BACKGROUND

Fracture healing can be impeded or even compromised by various factors, resulting in a growing number of patients suffering. The lncRNA LINC-PINT has garnered attention for its latent role in enhancing fracture healing, but its specific functions in this process remain unclear.

OBJECTIVES

The primary objective of this study is to investigate the clinical relevance and underlying molecular mechanisms of LINC-PINT in delayed fracture healing (DFH), while also assessing its potential as an early diagnostic biomarker.

MATERIALS AND METHODS

The expression levels of LINC-PINT were measured in the serum of DFH patients and those with normal fracture healing using RT-qPCR. In MC3T3-E1 cells, the study investigated the influence on the expression of differentiation-related protein, cell viability, and apoptosis through the modulation of LINC-PINT and miR-324-3p. To elucidate the targeting relationship between LINC-PINT, miR-324-3p, and BMP2, a dual-luciferase reporter assay was employed.

RESULTS

The findings revealed a significant downregulation of LINC-PINT expression in DFH patients. LINC-PINT showed high sensitivity and specificity as a diagnostic marker for DFH. In MC3T3-E1 cells, LINC-PINT overexpression markedly enhanced the expression levels of ALP, OCN, Runx2, and OPN, improved cell viability, and inhibited apoptosis. LINC-PINT negatively regulated miR-324-3p, and the effects of LINC-PINT were counteracted by miR-324-3p. LINC-PINT was found to regulate BMP2 by targeting miR-324-3p.

CONCLUSION

LINC-PINT could serve as an early diagnostic biomarker for DFH and slow the progression of DFH by modulating BMP2 through the targeted regulation of miR-324-3p. This research presents new molecular targets for the diagnosis and treatment of DFH.

Development of citric acid-based biomaterials for biomedical applications

The development of bioactive materials with controllable preparation is of great significance for biomedical engineering. Citric acid-based biomaterials are one of the few bioactive materials with many advantages such as simple synthesis, controllable structure, biocompatibility, biomimetic viscoelastic mechanical behavior, controllable biodegradability, and further functionalization. In this paper, we review the development of multifunctional citrate-based biomaterials for biomedical applications, and summarize their multifunctional properties in terms of physical, chemical, and biological aspects, and finally the applications of citrate-based biomaterials in biomedical engineering, including bone tissue engineering, skin tissue engineering, drug/cell delivery, vascular and neural tissue engineering, and bioimaging.

Recent Biomedical Applications of Functional Materials Based on Polyhedral Oligomeric Silsesquioxane (POSS)

Polyhedral oligomeric silsesquioxane (POSS) is a 3D, cage-like nanoparticle with an inorganic Si-O-Si core and eight tunable corner functional groups. Its well-defined structure grants it distinctive physical, chemical, and biological properties and has been widely used for preparing high-performance materials. Recently, click chemistry has enabled the synthesis of various functional POSS-based materials for diverse biomedical applications. This article reviews the recent applications of POSS-based materials in the biomedical field, including cancer treatment, tissue engineering, antibacterial use, and biomedical imaging. Representative examples are discussed in detail. Among the various POSS-based applications, cancer treatment and tissue engineering are the most important. Finally, this review presents the current limitations of POSS-based materials and provides guidance for future research.

Advances in DNA nanotechnology for chronic wound management: Innovative functional nucleic acid nanostructures for overcoming key challenges

Chronic wound management is affected by three primary challenges: bacterial infection, oxidative stress and inflammation, and impaired regenerative capacity. Conventional treatment methods typically fail to deliver optimal outcomes, thus highlighting the urgency to develop innovative materials that can address these issues and improve efficacy. Recent advances in DNA nanotechnology have garnered significant interest, particularly in the field of functional nucleic acid (FNA) nanomaterials, owing to their exceptional biocompatibility, programmability, and therapeutic potential. Among them, FNAs with unique nanostructures have garnered considerable attention. First, they inherit the biological properties of FNAs, including biocompatibility, reactive oxygen species (ROS)-scavenging capabilities, and modulation of cellular functions. Second, based on a precise design, these nanostructures exhibit superior physical properties, stability, and cellular uptake. Third, by leveraging the programmability of DNA strands, FNA nanostructures can be customized to accommodate therapeutic nucleic acids, peptides, and small-molecule drugs, thereby enabling a stable and controlled drug delivery system. These unique characteristics enable the use of FNA nanostructures to effectively address the major challenges in chronic wound management. This review focuses on various FNA nanostructures, including tetrahedral framework nucleic acids (tFNAs), DNA hydrogels, DNA origami, and rolling-circle amplification (RCA) DNA assembly. Additionally, a summary of recent advancements in their design and application for chronic wound management as well as insights for future research in this field are provided.

In-situ hydrogen-generating injectable short fibers for osteoarthritis treatment by alleviating oxidative stress

Hydrogen (H₂) has great potential in the treatment of osteoarthritis, but its rapid diffusion and short retention time make it difficult to exert stable therapeutic effects. This study developed a short-fiber injectable material that can continuously generate hydrogen in situ to eliminate reactive oxygen species (ROS), alleviate oxidative stress and inflammation, and promote tissue repair. We prepared H-Si nanosheets with high hydrogen generation efficiency using a wet chemical exfoliation method and combined them with GelMA short fibers via electrospinning technology, achieving the in situ delivery of H-Si nanosheets and regulated hydrogen generation rate through the encapsulation and degradation of GelMA, ultimately achieving continuous and controlled hydrogen supply and stable therapeutic effects for osteoarthritis. In vitro and in vivo experiments confirmed the safety and efficacy of this material. The results showed that the material could continuously and efficiently generate hydrogen in simulated physiological environments (100 mg of material could generate 8.6 % hydrogen), effectively eliminate cellular reactive oxygen species (ROS positive rate reduced by 85.89 %), reduce cellular senescence and apoptosis (cell death rate decreased by 52 %, SA-βgal expression decreased by 78.3 %), promote normal chondrocyte function (Col II expression increased by 67.4 %, Ki67 expression increased by 87.5 %), and improve osteoarthritis in rats (OARSI score increased by 216 %). The in situ hydrogen generation and control system designed in this study provides a new method for the hydrogen's local and stable treatment of osteoarthritis. STATEMENT OF SIGNIFICANCE: Hydrogen (H₂) has great potential in the treatment of osteoarthritis by alleviating oxidative stress, but its rapid diffusion and short retention time make it difficult to exert stable therapeutic effects. This study introduces an innovative injectable material combining H-Si nanosheets and GelMA short fibers to address this issue. By enabling continuous in situ hydrogen generation, this material effectively eliminates reactive oxygen species, reduces oxidative stress and inflammation, and promotes tissue repair. In vitro and in vivo experiments demonstrate its high hydrogen generation efficiency, safety, and therapeutic efficacy, offering a promising new approach for osteoarthritis management.

An injectable self-lubricating supramolecular polymer hydrogel loaded with platelet lysate to boost osteoarthritis treatment

Globally, osteoarthritis (OA) is the most prevalent joint disease and is characterized by infiltration of M1 macrophages in the synovium, anabolic-catabolic imbalance of the extracellular matrix (ECM), increased articular shear force and overproduction of reactive oxygen species (ROS). Disease-modifying OA drugs are not yet available, and treatments for OA focus solely on reducing pain and inflammation and have limited therapeutic effect. Herein, we developed an injectable self-lubricating poly(N-acryloyl alaninamide) (PNAAA) hydrogel loaded with platelet lysate (PL) (termed "PNAAA@PL") for treating OA. Tribological and drug release tests revealed suitable lubrication properties and sustained release of bioactive factors in PNAAA@PL. In vitro experiments showed that PNAAA@PL alleviated interleukin-1β (IL-1β)-induced anabolic-catabolic imbalance of chondrocytes and repolarized pro-inflammatory M1 macrophages to the anti-inflammatory M2 phenotype via intracellular ROS scavenging. Additionally, the PNAAA@PL hydrogel enhanced the migratory capacity and chemotaxis ability of stem cells, which are essential for chondrogenesis. In vivo, the functionalized PNAAA@PL hydrogel acted like synovial fluid following intra-articular injection into a rat OA model with anterior cruciate ligament transection, ultimately attenuating cartilage degeneration and synovitis. According to molecular mechanism studies, PNAAA@PL repairs cartilage in the OA model by inhibiting the NF-ĸB pathway. Overall, this self-lubricating PNAAA@PL hydrogel offers a comprehensive strategy for preventing OA progression by engineering a biophysiochemical microenvironment to generate high-quality hyaline cartilage.

Polydopamine-coated polycaprolactone/carbon nanotube fibrous scaffolds loaded with basic fibroblast growth factor for wound healing

Image 1.

Collagen as the extracellular matrix biomaterials in the arena of medical sciences

Collagen is a multipurpose material that has several applications in the health care, dental care, and pharmaceutical industries. Crosslinked compacted solids or lattice-like gels can be made from collagen. Biocompatibility, biodegradability, and wound-healing properties make collagen a popular scaffold material for cardiovascular, dentistry, and bone tissue engineering. Due to its essential role in the control of several of these processes, collagen has been employed as a wound-healing adjunct. It forms a major component of the extracellular matrix and regulates wound healing in its fibrillar or soluble forms. Collagen supports cardiovascular and other soft tissues. Oral wounds have been dressed with resorbable forms of collagen for closure of graft and extraction sites, and to aid healing. This present review is concentrated on the use of collagen in bone regeneration, wound healing, cardiovascular tissue engineering, and dentistry.

Diabetes Mellitus Inhibits Hair Follicle Regeneration by Inducing Macrophage Reprogramming-Mediated Pyroptosis

Background

Diabetes mellitus (DM) is known to inhibit skin self-renewal and hair follicle stem cell (HFSC) activation, which may be key in the formation of chronic diabetic wounds. This study aimed to investigate the reasons behind the suppression of HFSC activation in DM mice.

Methods

Type 1 DM (T1DM) was induced in 6-week-old mice via streptozotocin, and hair follicle growth was subsequently monitored. RNA sequencing, bioinformatics analyses, qRT‒PCR, immunostaining, and cellular experiments were carried out to investigate the underlying mechanisms involved.

Results

T1DM inhibited HFSC activation, which correlated with an increase in caspase-dependent programmed cell death. Additionally, T1DM triggered apoptosis and pyroptosis, predominantly in HFSCs and epidermal regions, with pyroptosis being more pronounced in the inner root sheath of hair follicles. Notably, significant cutaneous immune imbalances were observed, particularly in macrophages. Cellular experiments demonstrated that M1 macrophages inhibited HaCaT cell proliferation and induced cell death, whereas high-glucose environments alone did not have the same effect.

Conclusion

T1DM inhibits HFSC activation via macrophage reprogramming-mediated caspase-dependent pyroptosis, and there is a significant regional characterization of cell death. Moreover, T1DM-induced programmed cell death in the skin may be more closely related to immune homeostasis imbalance than to hyperglycemia itself. These findings shed light on the pathogenesis of diabetic ulcers and provide a theoretical basis for the use of hair follicle grafts in wound repair.

Highly spontaneous spin polarization engineering of single-atom artificial antioxidases towards efficient ROS elimination and tissue regeneration

The creation of atomic catalytic centers has emerged as a conducive path to design efficient nanobiocatalysts to serve as artificial antioxidases (AAOs) that can mimic the function of natural antioxidases to scavenge noxious reactive oxygen species (ROS) for protecting stem cells and promoting tissue regeneration. However, the fundamental mechanisms of diverse single-atom sites for ROS biocatalysis remain ambiguous. Herein, we show that highly spontaneous spin polarization mediates the hitherto unclear origin of H2O2-elimination activities in engineering ferromagnetic element (Fe, Co, Ni)-based AAOs with atomic centers. The experimental and theoretical results reveal that Fe-AAO exhibits the best catalase-like kinetics and turnover number, while Co-AAO shows the highest glutathione peroxidase-like activity and turnover number. Furthermore, our investigations prove that both Fe-AAO and Co-AAO can effectively secure the functions of stem cells in high ROS microenvironments and promote the repair of injured tendon tissue by scavenging H2O2 and other ROS. We believe that the proposed highly spontaneous spin polarization engineering of ferromagnetic element-based AAOs will provide essential guidance and practical opportunities for developing efficient AAOs for eliminating ROS, protecting stem cells, and accelerating tissue regeneration.

Graphene Quantum Dots Reduce Hypertrophic Scar by Inducing Myofibroblasts To Be a Quiescent State

Contrary to the initial belief that myofibroblasts are terminally differentiated cells, myofibroblasts have now been widely recognized as an activation state that is reversible. Therefore, strategies targeting myofibroblast to be a quiescent state may be an effective way for antihypertrophic scar therapy. Graphene quantum dots (GQDs), a novel zero-dimensional and carbon-based nanomaterial, have recently garnered significant interest in nanobiomedicine, owing to their excellent biocompatibility, tunable photoluminescence, and superior physiological stability. Although multiple nanoparticles have been used to alleviate hypertrophic scars, a GQD-based therapy has not been reported. Our in vivo studies showed that GQDs exhibited significant antiscar efficacy, with scar appearance improvement, collagen reduction and rearrangement, and inhibition of myofibroblast overproliferation. Further in vitro experiments revealed that GQDs inhibited α-SMA expression, collagen synthesis, and cell proliferation and migration, inducing myofibroblasts to become quiescent fibroblasts. Mechanistic studies have demonstrated that the effect of GQDs on myofibroblast proliferation blocked cell cycle progression by disrupting the cyclin-CDK-E2F axis. This study suggests that GQDs, which promote myofibroblast-to-fibroblast transition, could be a novel antiscar nanomedicine for the treatment of hypertrophic scars and other types of pathological fibrosis.

In vitro vascularized liver tumor model based on a microfluidic inverse opal scaffold for immune cell recruitment investigation

Liver cancer, characterized as a kind of malignant tumor within the digestive system, poses great health harm, and immune escape stands out as an important reason for its occurrence and development. Chemokines, pivotal in guiding immune cells' migration, is necessary to initiate and deliver an effective anti-tumor immune response. Therefore, understanding the chemotactic environment and identifying chemokines that regulate recruitment of immune cells to the tumor microenvironment (TME) are critical to improve current immunotherapy interventions. Herein, we report a well-defined inverse opal scaffold generated with a microfluidic emulsion template for the construction of a vascularized liver tumor model, offering insights into immune cells' recruitment. Due to the excellent 3D porous morphology of the inverse opal scaffold, human hepatocellular carcinoma cells can aggregate in the pores of the scaffold to form uniform multicellular tumor spheroids. More attractively, the vascularized liver tumor model can be achieved by constructing a 3D co-culture system involving endothelial cells and hepatocellular carcinoma cells. The results demonstrate that the 3D co-cultured tumor cells increase the neutrophil chemokines remarkably and recruit neutrophils to tumor tissues, then promote tumor progression. This approach opens a feasible avenue for realizing a vascularized liver tumor model with a reliable immune microenvironment close to that of a solid tumor of liver cancer.

Remodeling and Regenerative Properties of Fully Absorbable Meshes for Abdominal Wall Defect Repair: A Systematic Review and Meta-Analysis of Animal Studies

Fully absorbable meshes can repair abdominal wall defects and effectively reduce the incidence of complications, but different types of fully absorbable meshes have different remodeling and regeneration effects. In order to investigate and compare the effects of different fully absorbable meshes on remodeling and regeneration in animals and reduce the biological risk of clinical translation, SYRCLE was adopted to evaluate the methodological quality of the included studies, and GRADE and ConQual were used to evaluate the quality of evidence. According to the inclusion and exclusion criteria, a total of 22 studies related to fully absorbable meshes were included in this systematic review. These results showed that fiber-based synthetic materials and fiber-based natural materials exhibited better restorative and regenerative effects indicated by infiltration and neovascularization, when compared with a porcine acellular dermal matrix. In addition, the human acellular dermal matrix was found to have a similar regenerative effect on the host extracellular matrix and scaffold degradation compared to the porcine acellular dermal matrix, porcine intestinal submucosa, and fiber-based natural materials, but it offered higher tensile strength than the other three. The quality of the evidence in this field was found to be poor. The reasons for downgrading were analyzed, and recommendations for future research included more rigor in study design, more transparency in result reporting, more standardization of animal models and follow-up time for better evaluation of the remodeling and regenerative performance of abdominal wall hernia repair meshes, and less biological risk in clinical translation.