Preparing the ground for tissue regeneration: from mechanism to therapy

Comprehensive combined analysis of physician-initiated phase II and III clinical trials on a cultured human corneal endothelial cell product for treating bullous keratopathy

To evaluate the efficacy and safety of a cultured human corneal endothelial cell (cHCEC) product in eyes with bullous keratopathy (BK). Combined analysis of multicenter phase II and III clinical trials. This analysis involved 15 BK eyes in the phase II trial and 12 BK eyes in the phase III trial that underwent cHCEC transplant therapy. Safety was assessed in all the cases. Efficacy was assessed in 17 cases with exclusion of the low- and medium-dose groups in the phase II trial. The primary endpoint was a corneal endothelial cell density of 1000 cells/mm2 or more at 24 weeks post-transplant, which was attained in 94.1% of the eyes (16 of 17), with a 95% CI of 71.3-99.9%. Additionally, 82.4% of the eyes (14 of 17) met the secondary endpoint of reduction in corneal thickness to less than 630 µm without corneal epithelial edema within the same time frame, with a 95% CI of 56.6-96.2%. The mean decrease in corneal thickness from baseline to 24 weeks post-transplant was -187.4 µm (95% CI, -240.2 µm to -134.5 µm). Furthermore, all the eyes exhibited improvement in best-corrected visual acuity from baseline to 24 weeks post-transplant (95% CI, 80.5-100.0%). By 24 weeks post-transplant, 88.9% of the patients (24 of 27) had experienced adverse events, which were mostly local, mild, and transient. The cHCEC product of this study reconstitutes the corneal endothelial layer with high cellular density and restores corneal thickness and improves visual acuity.

Liver cirrhosis: molecular mechanisms and therapeutic interventions

Liver cirrhosis is the end-stage of chronic liver disease, characterized by inflammation, necrosis, advanced fibrosis, and regenerative nodule formation. Long-term inflammation can cause continuous damage to liver tissues and hepatocytes, along with increased vascular tone and portal hypertension. Among them, fibrosis is the necessary stage and essential feature of liver cirrhosis, and effective antifibrosis strategies are commonly considered the key to treating liver cirrhosis. Although different therapeutic strategies aimed at reversing or preventing fibrosis have been developed, the effects have not be more satisfactory. In this review, we discussed abnormal changes in the liver microenvironment that contribute to the progression of liver cirrhosis and highlighted the importance of recent therapeutic strategies, including lifestyle improvement, small molecular agents, traditional Chinese medicine, stem cells, extracellular vesicles, and gut remediation, that regulate liver fibrosis and liver cirrhosis. Meanwhile, therapeutic strategies for nanoparticles are discussed, as are their possible underlying broad application and prospects for ameliorating liver cirrhosis. Finally, we also reviewed the major challenges and opportunities of nanomedicine‒biological environment interactions. We hope this review will provide insights into the pathogenesis and molecular mechanisms of liver cirrhosis, thus facilitating new methods, drug discovery, and better treatment of liver cirrhosis.

Inhalable SPRAY nanoparticles by modular peptide assemblies reverse alveolar inflammation in lethal Gram-negative bacteria infection

Current pharmacotherapy remains futile in acute alveolar inflammation induced by Gram-negative bacteria (GNB), eliciting consequent respiratory failure. The release of lipid polysaccharides after antibiotic treatment and subsequent progress of proinflammatory cascade highlights the necessity to apply effective inflammation management simultaneously. This work describes modular self-assembling peptides for rapid anti-inflammatory programming (SPRAY) to form nanoparticles targeting macrophage specifically, having anti-inflammation and bactericidal functions synchronously. SPRAY nanoparticles accelerate the self-delivery process in macrophages via lysosomal membrane permeabilization, maintaining anti-inflammatory programming in macrophages with efficacy close to T helper 2 cytokines. By pulmonary deposition, SPRAY nanoparticles effectively suppress inflammatory infiltration and promote alveoli regeneration in murine aseptic acute lung injury. Moreover, SPRAY nanoparticles efficiently eradicate multidrug-resistant GNB in alveoli by disrupting bacterial membrane. The universal molecular design of SPRAY nanoparticles provides a robust and clinically unseen local strategy in reverse acute inflammation featured by a high accumulation of proinflammatory cellularity and drug-resistant bacteria.

Local administration of regulatory T cells promotes tissue healing

Regulatory T cells (Tregs) are crucial immune cells for tissue repair and regeneration. However, their potential as a cell-based regenerative therapy is not yet fully understood. Here, we show that local delivery of exogenous Tregs into injured mouse bone, muscle, and skin greatly enhances tissue healing. Mechanistically, exogenous Tregs rapidly adopt an injury-specific phenotype in response to the damaged tissue microenvironment, upregulating genes involved in immunomodulation and tissue healing. We demonstrate that exogenous Tregs exert their regenerative effect by directly and indirectly modulating monocytes/macrophages (Mo/MΦ) in injured tissues, promoting their switch to an anti-inflammatory and pro-healing state via factors such as interleukin (IL)-10. Validating the key role of IL-10 in exogenous Treg-mediated repair and regeneration, the pro-healing capacity of these cells is lost when Il10 is knocked out. Additionally, exogenous Tregs reduce neutrophil and cytotoxic T cell accumulation and IFN-γ production in damaged tissues, further dampening the pro-inflammatory Mo/MΦ phenotype. Highlighting the potential of this approach, we demonstrate that allogeneic and human Tregs also promote tissue healing. Together, this study establishes exogenous Tregs as a possible universal cell-based therapy for regenerative medicine and provides key mechanistic insights that could be harnessed to develop immune cell-based therapies to enhance tissue healing.

LIFR regulates cholesterol-driven bidirectional hepatocyte-neutrophil cross-talk to promote liver regeneration

Liver regeneration is under metabolic and immune regulation. Despite increasing recognition of the involvement of neutrophils in regeneration, it is unclear how the liver signals to the bone marrow to release neutrophils after injury and how reparative neutrophils signal to hepatocytes to reenter the cell cycle. Here we report that loss of the liver tumour suppressor Lifr in mouse hepatocytes impairs, whereas overexpression of leukaemia inhibitory factor receptor (LIFR) promotes liver repair and regeneration after partial hepatectomy or toxic injury. In response to physical or chemical damage to the liver, LIFR from hepatocytes promotes the secretion of cholesterol and CXCL1 in a STAT3-dependent manner, leading to the efflux of bone marrow neutrophils to the circulation and damaged liver. Cholesterol, via its receptor ERRα, stimulates neutrophils to secrete hepatocyte growth factor to accelerate hepatocyte proliferation. Altogether, our findings reveal a LIFR-STAT3-CXCL1-CXCR2 axis and a LIFR-STAT3-cholesterol-ERRα-hepatocyte growth factor axis that form bidirectional hepatocyte-neutrophil cross-talk to repair and regenerate the liver.

Microenvironment-sensitive nanozymes for tissue regeneration

Tissue defect is one of the significant challenges encountered in clinical practice. Nanomaterials, including nanoparticles, nanofibers, and metal-organic frameworks, have demonstrated an extensive potential in tissue regeneration, offering a promising avenue for future clinical applications. Nonetheless, the intricate landscape of the inflammatory tissue microenvironment has engendered challenges to the efficacy of nanomaterial-based therapies. This quandary has spurred researchers to pivot towards advanced nanotechnological remedies for overcoming these therapeutic constraints. Among these solutions, microenvironment-sensitive nanozymes have emerged as a compelling instrument with the capacity to reshape the tissue microenvironment and enhance the intricate process of tissue regeneration. In this review, we summarize the microenvironmental characteristics of damaged tissues, offer insights into the rationale guiding the design and engineering of microenvironment-sensitive nanozymes, and explore the underlying mechanisms that underpin these nanozymes' responsiveness. This analysis includes their roles in orchestrating cellular signaling, modulating immune responses, and promoting the delicate process of tissue remodeling. Furthermore, we discuss the diverse applications of microenvironment-sensitive nanozymes in tissue regeneration, including bone, soft tissue, and cartilage regeneration. Finally, we shed our sights on envisioning the forthcoming milestones in this field, prospecting a future where microenvironment-sensitive nanozymes contribute significantly to the development of tissue regeneration and improved clinical outcomes.

Zfp697 is an RNA-binding protein that regulates skeletal muscle inflammation and remodeling

Skeletal muscle atrophy is a morbidity and mortality risk factor that happens with disuse, chronic disease, and aging. The tissue remodeling that happens during recovery from atrophy or injury involves changes in different cell types such as muscle fibers, and satellite and immune cells. Here, we show that the previously uncharacterized gene and protein Zfp697 is a damage-induced regulator of muscle remodeling. Zfp697/ZNF697 expression is transiently elevated during recovery from muscle atrophy or injury in mice and humans. Sustained Zfp697 expression in mouse muscle leads to a gene expression signature of chemokine secretion, immune cell recruitment, and extracellular matrix remodeling. Notably, although Zfp697 is expressed in several cell types in skeletal muscle, myofiber-specific Zfp697 genetic ablation in mice is sufficient to hinder the inflammatory and regenerative response to muscle injury, compromising functional recovery. We show that Zfp697 is an essential mediator of the interferon gamma response in muscle cells and that it functions primarily as an RNA-interacting protein, with a very high number of miRNA targets. This work identifies Zfp697 as an integrator of cell-cell communication necessary for tissue remodeling and regeneration.

High-Dose Neutrophil-Depleted Platelet-Rich Plasma Therapy for Knee Osteoarthritis: A Retrospective Study

Background/Objectives: Encouraging results have been reported for Platelet-Rich Plasma (PRP) treatment for knee osteoarthritis (KOA). This study reports the efficacy and safety of a high dose of neutrophile and red-blood-cell-depleted PRP to treat patients with KOA. Methods: A total of 212 consecutive patients diagnosed with Kellgren-Lawrence (KL) grading 1-3 KOA chronic knee pain for at least 1 year were treated with three injections at 15-day intervals with a high dose of neutrophil-depleted PRP (4 billion platelets). Clinical outcomes were retrospectively recorded as the percentage of responders at 3-, 6-, and 12-month follow-up, following the OMERACT-OARSI criteria. Pain, through the VAS score and WOMAC score, was also been recorded. Results: A total of 4 mL of PRP containing 4 × 109 platelets was obtained by single-spin centrifugation and injected intra-articularly into each patient with no preactivation. The overall responder rate of patients responding to the OMERACT-OARSI criteria at 3, 6, and 12 months was 68.9%, 72.7%, and 70.6%, respectively. A significant improvement in VAS and WOMAC scores at 3-, 6-, and 12-month follow-up compared to the pretreatment value (p < 0.01) was observed. The lowest VAS score was observed at 6 months overall and in all three KL-graded groups. The KL2 groups showed the best results regarding pain reduction and their WOMAC score at 6 months (p < 0.01). Conclusions: For KL1-3 KOA, a high dosage of neutrophil-depleted PRP is a successful treatment. It has long-lasting effects that last up to one year, relieves symptoms, and may slow the advancement of the disease.

Antioxidant and Immunomodulatory Polymer Vesicles for Effective Diabetic Wound Treatment through ROS Scavenging and Immune Modulating

Chronic diabetic wound patients usually show high glucose levels and systemic immune disorder, resulting in high reactive oxygen species (ROS) levels and immune cell dysfunction, prolonged inflammation, and delayed wound healing. Herein, we prepared an antioxidant and immunomodulatory polymer vesicle for diabetic wound treatment. This vesicle is self-assembled from poly(ε-caprolactone)36-block-poly[lysine4-stat-(lysine-mannose)22-stat-tyrosine)16] ([PCL36-b-P[Lys4-stat-(Lys-Man)22-stat-Tyr16]). Polytyrosine is an antioxidant polypeptide that can scavenge ROS. d-Mannose was introduced to afford immunomodulatory functions by promoting macrophage transformation and Treg cell activation through inhibitory cytokines. The mice treated with polymer vesicles showed 23.7% higher Treg cell levels and a 91.3% higher M2/M1 ratio than those treated with PBS. Animal tests confirmed this vesicle accelerated healing and achieved complete healing of S. aureus-infected diabetic wounds within 8 days. Overall, this is the first antioxidant and immunomodulatory vesicle for diabetic wound healing by scavenging ROS and regulating immune homeostasis, opening new avenues for effective diabetic wound healing.

Fibroblast and myofibroblast activation in normal tissue repair and fibrosis

The term 'fibroblast' often serves as a catch-all for a diverse array of mesenchymal cells, including perivascular cells, stromal progenitor cells and bona fide fibroblasts. Although phenotypically similar, these subpopulations are functionally distinct, maintaining tissue integrity and serving as local progenitor reservoirs. In response to tissue injury, these cells undergo a dynamic fibroblast-myofibroblast transition, marked by extracellular matrix secretion and contraction of actomyosin-based stress fibres. Importantly, whereas transient activation into myofibroblasts aids in tissue repair, persistent activation triggers pathological fibrosis. In this Review, we discuss the roles of mechanical cues, such as tissue stiffness and strain, alongside cell signalling pathways and extracellular matrix ligands in modulating myofibroblast activation and survival. We also highlight the role of epigenetic modifications and myofibroblast memory in physiological and pathological processes. Finally, we discuss potential strategies for therapeutically interfering with these factors and the associated signal transduction pathways to improve the outcome of dysregulated healing.

How obesity affects adipocyte turnover

Cellular turnover is fundamental for tissue homeostasis and integrity. Adipocyte turnover, accounting for 4% of the total cellular mass turnover in humans, is essential for adipose tissue homeostasis during metabolic stress. In obesity, an altered adipose tissue microenvironment promotes adipocyte death. To clear dead adipocytes, macrophages are recruited and form a distinctive structure known as crown-like structure; subsequently, new adipocytes are generated from adipose stem and progenitor cells in the adipogenic niche to replace dead adipocytes. Accumulating evidence indicates that adipocyte death, clearance, and adipogenesis are sophisticatedly orchestrated during adipocyte turnover. In this Review, we summarize our current understandings of each step in adipocyte turnover, discussing its key players and regulatory mechanisms.

Bioactive Glass and Silica Particles for Skeletal and Cardiac Muscle Tissue Regeneration

When skeletal and cardiac tissues are damaged, surgical approaches are not always successful and tissue regeneration approaches are investigated. Reports in the literature indicate that silica nanoparticles and bioactive glasses (BGs), including silicate bioactive glasses (e.g., 45S5 BG), phosphate glass fibers, boron-doped mesoporous BGs, borosilicate glasses, and aluminoborates, are promising for repairing skeletal muscle tissue. Silica nanoparticles and BGs have been combined with polymers to obtain aligned nanofibers and to maintain controlled delivery of nanoparticles for skeletal muscle repair. The literature indicates that cardiac muscle regeneration can be also triggered by the ionic products of BGs. This was observed to be due to the release of vascular endothelial growth factor and other growth factors from cardiomyocytes, which regulate endothelial cells to form capillary structures (angiogenesis). Specific studies, including both in vitro and in vivo approaches, are reviewed in this article. The analysis of the literature indicates that although the research field is still very limited, BGs are showing great promise for muscle tissue engineering and further research in the field should be carried out to expand our basic knowledge on the application of BGs in muscle (skeletal and cardiac) tissue regeneration. Impact statement This review highlights the potential of silica particles and bioactive glasses (BGs) for skeletal and cardiac tissue regeneration. These biomaterials create scaffolds triggering muscle cell differentiation. Ionic products from BGs stimulate growth factors, supporting angiogenesis in cardiac tissue repair. Further research is required to expand our know-how on silica particles and BGs in muscle tissue engineering.

Advanced gene nanocarriers/scaffolds in nonviral-mediated delivery system for tissue regeneration and repair

Tissue regeneration technology has been rapidly developed and widely applied in tissue engineering and repair. Compared with traditional approaches like surgical treatment, the rising gene therapy is able to have a durable effect on tissue regeneration, such as impaired bone regeneration, articular cartilage repair and cancer-resected tissue repair. Gene therapy can also facilitate the production of in situ therapeutic factors, thus minimizing the diffusion or loss of gene complexes and enabling spatiotemporally controlled release of gene products for tissue regeneration. Among different gene delivery vectors and supportive gene-activated matrices, advanced gene/drug nanocarriers attract exceptional attraction due to their tunable physiochemical properties, as well as excellent adaptive performance in gene therapy for tissue regeneration, such as bone, cartilage, blood vessel, nerve and cancer-resected tissue repair. This paper reviews the recent advances on nonviral-mediated gene delivery systems with an emphasis on the important role of advanced nanocarriers in gene therapy and tissue regeneration.

Rejuvenating fecal microbiota transplant enhances peripheral nerve repair in aged mice by modulating endoneurial inflammation

Peripheral nerve injury (PNI) resulting from trauma or neuropathies can cause significant disability, and its prognosis deteriorates with age. Emerging evidence suggests that gut dysbiosis and reduced fecal short-chain fatty acids (SCFAs) contribute to an age-related systemic hyperinflammation (inflammaging), which hinders nerve recovery after injury. This study thus aimed to evaluate the pro-regenerative effects of a rejuvenating fecal microbiota transplant (FMT) in a preclinical PNI model using aged mice. Aged C57BL/6 mice underwent bilateral crush injuries to their sciatic nerves. Subsequently, they either received FMT from young donors at three and four days after the injury or retained their aged gut microbiota. We analyzed gut microbiome composition and SCFA concentrations in fecal samples. The integrity of the ileac mucosal barrier was assessed by immunofluorescence staining of Claudin-1. Flow cytometry was utilized to examine immune cells and cytokine production in the ileum, spleen, and sciatic nerve. Various assessments, including behavioural tests, electrophysiological studies, and morphometrical analyses, were conducted to evaluate peripheral nerve function and repair following injury. Rejuvenating FMT reversed age-related gut dysbiosis by increasing Actinobacteria, especially Bifidobacteriales genera. This intervention also led to an elevation of gut SCFA levels and mitigated age-related ileac mucosal leakiness in aged recipients. Additionally, it augmented the number of T-helper 2 (Th2) and regulatory T (Treg) cells in the ileum and spleen, with the majority being positive for anti-inflammatory interleukin-10 (IL-10). In sciatic nerves, rejuvenating FMT resulted in increased M2 macrophage counts and a higher IL-10 production by IL-10+TNF-α- M2 macrophage subsets. Ultimately, restoring a youthful gut microbiome in aged mice led to improved nerve repair and enhanced functional recovery after PNI. Considering that FMT is already a clinically available technique, exploring novel translational strategies targeting the gut microbiome to enhance nerve repair in the elderly seems promising and warrants further evaluation.

Infliximab Limits Injury in Myocardial Infarction

BACKGROUND

The purpose of this study was to investigate a therapeutic approach targeting the inflammatory response and consequent remodeling from ischemic myocardial injury.

METHODS AND RESULTS

Coronary thrombus aspirates were collected from patients at the time of ST-segment-elevation myocardial infarction and subjected to array-based proteome analysis. Clinically indistinguishable at myocardial infarction (MI), patients were stratified into vulnerable and resilient on the basis of 1-year left ventricular ejection fraction and death. Network analysis from coronary aspirates revealed prioritization of tumor necrosis factor-α signaling in patients with worse clinical outcomes. Infliximab, a tumor necrosis factor-α inhibitor, was infused intravenously at reperfusion in a porcine MI model to assess whether infliximab-mediated immune modulation impacts post-MI injury. At 3 days after MI (n=7), infliximab infusion increased proregenerative M2 macrophages in the myocardial border zone as quantified by immunofluorescence (24.1%±23.3% in infliximab versus 9.29%±8.7% in sham; P<0.01). Concomitantly, immunoassays of coronary sinus samples quantified lower troponin I levels (41.72±7.34 pg/mL versus 58.11±10.75 pg/mL; P<0.05) and secreted protein analysis revealed upregulation of injury-modifying interleukin-2, -4, -10, -12, and -18 cytokines in the infliximab-treated cohort. At 4 weeks (n=12), infliximab treatment resulted in significant protective influence, improving left ventricular ejection fraction (53.9%±5.4% versus 36.2%±5.3%; P<0.001) and reducing scar size (8.31%±10.9% versus 17.41%±12.5%; P<0.05).

CONCLUSIONS

Profiling of coronary thrombus aspirates in patients with ST-segment-elevation MI revealed highest association for tumor necrosis factor-α in injury risk. Infliximab-mediated immune modulation offers an actionable pathway to alter MI-induced inflammatory response, preserving contractility and limiting adverse structural remodeling.

Inflammation-Responsive Hydrogel Accelerates Diabetic Wound Healing through Immunoregulation and Enhanced Angiogenesis

Angiogenesis is a prominent component during the highly regulated process of wound healing. The application of exogenous vascular endothelial growth factor (VEGF) has shown considerable potential in facilitating angiogenesis. However, its effectiveness is often curtailed due to chronic inflammation and severe oxidative stress in diabetic wounds. Herein, an inflammation-responsive hydrogel incorporating Prussian blue nanoparticles (PBNPs) is designed to augment the angiogenic efficacy of VEGF. Specifically, the rapid release of PBNPs from the hydrogel under inflammatory conditions effectively alleviates the oxidative stress of the wound, therefore reprogramming the immune microenvironment to preserve the bioactivity of VEGF for enhanced angiogenesis. In vitro and in vivo studies reveal that the PBNPs and VEGF co-loaded hydrogel is biocompatible and possesses effective anti-inflammatory properties, thereby facilitating angiogenesis to accelerate the wound healing process in a type 2 diabetic mouse model.

Evaluation of Alginate Hydrogel Microstrands for Stromal Cell Encapsulation and Maintenance

Mesenchymal stromal cells (MSCs) have displayed potential in regenerating organ function due to their anti-fibrotic, anti-inflammatory, and regenerative properties. However, there is a need for delivery systems to enhance MSC retention while maintaining their anti-fibrotic characteristics. This study investigates the feasibility of using alginate hydrogel microstrands as a cell delivery vehicle to maintain MSC viability and phenotype. To accommodate cell implantation needs, we invented a Syringe-in-Syringe approach to reproducibly fabricate microstrands in small numbers with a diameter of around 200 µm and a porous structure, which would allow for transporting nutrients to cells by diffusion. Using murine NIH 3T3 fibroblasts and primary embryonic 16 (E16) salivary mesenchyme cells as primary stromal cell models, we assessed cell viability, growth, and expression of mesenchymal and fibrotic markers in microstrands. Cell viability remained higher than 90% for both cell types. To determine cell number within the microstrands prior to in vivo implantation, we have further optimized the alamarBlue assay to measure viable cell growth in microstrands. We have shown the effect of initial cell seeding density and culture period on cell viability and growth to accommodate future stromal cell delivery and implantation. Additionally, we confirmed homeostatic phenotype maintenance for E16 mesenchyme cells in microstrands.

TMT-Based Quantitative Proteomic Analysis Reveals the Key Role of Cell Proliferation and Apoptosis in Intestine Regeneration of Apostichopus japonicus

Sea cucumbers are widely known for their powerful regenerative abilities, which allow them to regenerate a complete digestive tract within a relatively short time following injury or autotomy. Recently, even though the histological changes and cellular events in the processes of intestinal regeneration have been extensively studied, the molecular machinery behind this faculty remains unclear. In this study, tandem mass tag (TMT)-based quantitation was utilized to investigate protein abundance changes during the process of intestine regeneration. Approximately 538, 445, 397, 1012, and 966 differential proteins (DEPs) were detected (p < 0.05) between the normal and 2, 7, 12, 20, and 28 dpe stages, respectively. These DEPs also mainly focus on pathways of cell proliferation and apoptosis, which were further validated by 5-Ethynyl-2'-deoxyuridine (EdU) or Tunel-based flow cytometry assay. These findings provide a reference for a comprehensive understanding of the regulatory mechanisms of various stages of intestinal regeneration and provide a foundation for subsequent research on changes in cell fate in echinoderms.

NIBR-LTSi is a selective LATS kinase inhibitor activating YAP signaling and expanding tissue stem cells in vitro and in vivo

The YAP/Hippo pathway is an organ growth and size regulation rheostat safeguarding multiple tissue stem cell compartments. LATS kinases phosphorylate and thereby inactivate YAP, thus representing a potential direct drug target for promoting tissue regeneration. Here, we report the identification and characterization of the selective small-molecule LATS kinase inhibitor NIBR-LTSi. NIBR-LTSi activates YAP signaling, shows good oral bioavailability, and expands organoids derived from several mouse and human tissues. In tissue stem cells, NIBR-LTSi promotes proliferation, maintains stemness, and blocks differentiation in vitro and in vivo. NIBR-LTSi accelerates liver regeneration following extended hepatectomy in mice. However, increased proliferation and cell dedifferentiation in multiple organs prevent prolonged systemic LATS inhibition, thus limiting potential therapeutic benefit. Together, we report a selective LATS kinase inhibitor agonizing YAP signaling and promoting tissue regeneration in vitro and in vivo, enabling future research on the regenerative potential of the YAP/Hippo pathway.

Is there a role for N1-N2 neutrophil phenotypes in bone regeneration? A systematic review

PURPOSE

This review aims to provide an overview of the multiple functions of neutrophils, with the recognition of the inflammatory (N1) and regenerative (N2) phenotypes, in relation to fracture healing.

METHODS

A literature search was performed using the PubMed database. The quality of the articles was evaluated using critical appraisal checklists.

RESULTS

Thirty one studies were included in this review. These studies consistently support that neutrophils exert both beneficial and detrimental effects on bone regeneration, influenced by Tumor Necrosis Factor-α (TNF-α), Interleukin 8 (IL-8), mast cells, and macrophages. The N2 phenotype has recently emerged as one promoter of bone healing. The N1 phenotype has progressively been connected with inflammatory neutrophils during fracture healing.

CONCLUSIONS

This review has pinpointed various aspects and mechanisms of neutrophil influence on bone healing. The recognition of N1 and N2 neutrophil phenotypes potentially shed new light on the dynamic shifts taking place within the Fracture Hematoma (FH).

Iron-Single-Atom Nanozyme with NIR Enhanced Catalytic Activities for Facilitating MRSA-Infected Wound Therapy

Patients with methicillin-resistant Staphylococcus aureus (MRSA) infections may have higher death rates than those with non-drug-resistant infections. Nanozymes offer a promising approach to eliminating bacteria by producing reactive oxygen species. However, most of the conventional nanozyme technologies encounter significant challenges with respect to size, composition, and a naturally low number of active sites. The present study synthesizes a iron-single-atom structure (Fe-SAC) via nitrogen doped-carbon, a Fe-N5 catalyst (Fe-SAC) with a high metal loading (4.3 wt.%). This catalyst permits the development of nanozymes consisting of single-atom structures with active sites resembling enzymes, embedded within nanomaterials. Fe-SAC displays peroxidase-like activities upon exposure to H2O2. This structure facilitates the production of hydroxyl radicals, well-known for their strong bactericidal effects. Furthermore, the photothermal properties augment the bactericidal efficacy of Fe-SAC. The findings reveal that Fe-SAC disrupts the bacterial cell membranes and the biofilms, contributing to their antibacterial effects. The bactericidal properties of Fe-SAC are harnessed, which eradicates the MRSA infections in wounds and improves wound healing. Taken together, these findings suggest that single Fe atom nanozymes offer a novel perspective on the catalytic mechanism and design, holding immense potential as next-generation nanozymes.

Chitin: A versatile biopolymer-based functional therapy for cartilage regeneration

Chitin is the second most abundant biopolymer and its inherent biological characteristics make it ideal to use for tissue engineering. For many decades, its properties like non-toxicity, abundant availability, ease of modification, biodegradability, biocompatibility, and anti-microbial activity have made chitin an ideal biopolymer for drug delivery. Research studies have also shown many potential benefits of chitin in the formulation of functional therapy for cartilage regeneration. Chitin and its derivatives can be processed into 2D/3D scaffolds, hydrogels, films, exosomes, and nano-fibers, which make it a versatile and functional biopolymer in tissue engineering. Chitin is a biomimetic polymer that provides targeted delivery of mesenchymal stem cells, especially of chondrocytes at the injected donor sites to accelerate regeneration by enhancing cell proliferation and differentiation. Due to this property, chitin is considered an interesting polymer that has a high potential to provide targeted therapy in the regeneration of cartilage. Our paper presents an overview of the method of extraction, structure, properties, and functional role of this versatile biopolymer in tissue engineering, especially cartilage regeneration.

Beyond host defense and tissue injury: the emerging role of neutrophils in tissue repair

Neutrophils, the most abundant immune cells in human blood, play a fundamental role in host defense against invading pathogens and tissue injury. Neutrophils carry potentially lethal weaponry to the affected site. Inadvertent and perpetual neutrophil activation could lead to nonresolving inflammation and tissue damage, a unifying mechanism of many common diseases. The prevailing view emphasizes the dichotomy of their function, host defense versus tissue damage. However, tissue injury may also persist during neutropenia, which is associated with disease severity and poor outcome. Numerous studies highlight neutrophil phenotypic heterogeneity and functional versatility, indicating that neutrophils play more complex roles than previously thought. Emerging evidence indicates that neutrophils actively orchestrate resolution of inflammation and tissue repair and facilitate return to homeostasis. Thus, neutrophils mobilize multiple mechanisms to limit the inflammatory reaction, assure debris removal, matrix remodeling, cytokine scavenging, macrophage reprogramming, and angiogenesis. In this review, we will summarize the homeostatic and tissue-reparative functions and mechanisms of neutrophils across organs. We will also discuss how the healing power of neutrophils might be harnessed to develop novel resolution and repair-promoting therapies while maintaining their defense functions.

A Holistic Perspective on Living Aggregate

Aggregate is one of the most extensive existing modes of matters in the world. Besides the research objectives of inanimate systems in physical science, the entities in life science can be regarded as living aggregates, which are far from being thoroughly understood despite the great advances in molecular biology. Molecular biology follows the research philosophy of reductionism, which generally reduces the whole into parts to study. Although reductionism benefits the understanding of molecular behaviors, it encounters limitations when extending to the aggregate level. Holism is another epistemology comparable to reductionism, which studies objectives at the aggregate level, emphasizing the interactions and synergetic/antagonistic effects of a group of composed single entities in determining the characteristics of a whole. As a representative of holism, aggregation-induced emission (AIE) materials have made great achievements in the past two decades in both physical and life science. In particular, the unique properties of AIE materials endow them with in situ and real-time visual methods to investigate the inconsistency between microscopic molecules and macroscopic substances, offering researchers excellent toolkits to study living aggregates. The applications of AIE materials in life science are still in their infancy and worth expanding. In this Perspective, we summarize the research progress of AIE materials in unveiling some phenomena and processes of living systems, aiming to provide a general research approach from the viewpoint of holism. At last, insights into what we can do in the near future are also raised and discussed.

Carbon-based nanocomposites for biomedical applications

Carbon nanomaterials have attracted significant attention in the biomedical field, including for biosensing, drug delivery, and tissue engineering applications. Based on their inherent properties such as their unique structure and high conductivity, carbon nanomaterials can overcome the current limitations in biomedical research such as poor stability of biomolecules, low sensitivity and selectivity of biosensors, and difficulty in precise drug delivery. In addition, recently, several novel nanomaterials have been integrated with carbon nanomaterials to develop carbon-based nanocomposites for application in biomedical research. In this review, we discuss recent studies on carbon-based nanocomposites and their biomedical applications. First, we discuss the representative carbon nanomaterials and nanocomposites composed of carbon and other novel nanomaterials. Next, applications of carbon nanomaterials and nanocomposites in the biomedical field are discussed according to topics in the biomedical field. We have discussed the recent studies on biosensors, drug delivery, and tissue engineering. In conclusion, we believe that this review provides the potential and applicability of carbon nanomaterials and their nanocomposites and suggests future directions of the application of carbon-based nanocomposites in biomedical applications.

Effects of Addition of Lanthanum and Zinc Oxides on the Biological Properties of TiO2-SiO2-P2O5/CaO on Ion Exchange Resin for Bone Implantation

The spherical materials TiO2-SiO2-P2O5/CaO, TiO2-SiO2-P2O5/La2O3, and TiO2-SiO2-P2O5/ZnO deposited on the Tokem-250 cation exchanger have been synthesized with an alcoholic solution by the sol-gel method. The macroporous cation exchanger Tokem-250, which has high Ca2+, Zn2+, and La3+ ion selectivity, was used in the present study. This material has the ability to precipitate and mineralize calcium phosphates on its surface in biological media, since it has high porosity, a homogeneous structure with a uniform variation of elements, and the presence of active centers (Si4+, Ti4+) on the surface. The effect of lanthanum and zinc additives on biological properties has been studied. It was established that accumulation of Ca2+ and Mg2+ occurs faster on the surface of TiO2-SiO2-P2O5/ZnO in the SBF (simulated body fluid) model solution, showing higher reaction capacity. The amount of calcium and phosphorus ions on the surface of sample TiO2-SiO2-P2O5/La2O3 is greater due to the ability of lanthanum to coordinate a large number of ions (lanthanum coordination number is 10). The presence of zinc ions in the system causes the partial hemoglobin release from erythrocytes into the supernatant fluid. The samples with lanthanum ions reduce the amount of protein in plasma after incubation, which has a positive effect on the practical application.

Balance of Gata3 and Ramp2 in hepatocytes regulates hepatic vascular reconstitution in postoperative liver regeneration

BACKGROUND & AIMS

Post-hepatectomy liver failure (PHLF) leads to poor prognosis in patients undergoing hepatectomy, with hepatic vascular reconstitution playing a critical role. However, the regulators of hepatic vascular reconstitution remain unclear. In this study, we aimed to investigate the regulatory mechanisms of hepatic vascular reconstitution and identify biomarkers predicting PHLF in patients undergoing hepatectomy.

METHODS

Candidate genes that were associated with hepatic vascular reconstitution were screened using adeno-associated virus vectors in Alb-Cre-CRISPR/Cas9 mice subjected to partial hepatectomy. The biological activities of candidate genes were estimated using endothelial precursor transfusion and associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) models. The level of candidates was detected in biopsies from patients undergoing ALPPS. Risk factors for PHLF were also screened using retrospective data.

RESULTS

Downregulation of Gata3 and upregulation of Ramp2 in hepatocytes promoted the proliferation of liver sinusoidal endothelial cells and hepatic revascularization. Pigment epithelium-derived factor (PEDF) and vascular endothelial growth factor A (VEGFA) played opposite roles in regulating the migration of endothelial precursors from bone marrow and the formation of new sinusoids after hepatectomy. Gata3 restricted endothelial cell function in patient-derived hepatic organoids, which was abrogated by a Gata3 inhibitor. Moreover, overexpression of Gata3 led to higher mortality in ALPPS mice, which was improved by a PEDF-neutralizing antibody. The expression of Gata3/RAMP and PEDF/VEGFA tended to have a negative correlation in patients undergoing ALPPS. A nomogram incorporating multiple factors, such as serum PEDF/VEGF index, was constructed and could efficiently predict the risk of PHLF.

CONCLUSIONS

The balance of Gata3 and Ramp2 in hepatocytes regulates the proliferation of liver sinusoidal endothelial cells and hepatic revascularization via changes in the expression of PEDF and VEGFA, revealing potential targets for the prevention and treatment of PHLF.

IMPACT AND IMPLICATIONS

In this study, we show that the balance of Gata3 and Ramp2 in hepatocytes regulates hepatic vascular reconstitution by promoting a shift from pigment epithelium-derived factor (PEDF) to vascular endothelial growth factor A (VEGFA) expression during hepatectomy- or ALLPS (associating liver partition and portal vein ligation for staged hepatectomy)-induced liver regeneration. We also identified serum PEDF/VEGFA index as a potential predictor of post-hepatectomy liver failure in patients who underwent hepatectomy. This study improves our understanding of how hepatocytes contribute to liver regeneration and provides new targets for the prevention and treatment of post-hepatectomy liver failure.

STAT3 Decoy Oligodeoxynucleotides Suppress Liver Inflammation and Fibrosis in Liver Cancer Cells and a DDC-Induced Liver Injury Mouse Model

Liver damage caused by various factors results in fibrosis and inflammation, leading to cirrhosis and cancer. Fibrosis results in the accumulation of extracellular matrix components. The role of STAT proteins in mediating liver inflammation and fibrosis has been well documented; however, approved therapies targeting STAT3 inhibition against liver disease are lacking. This study investigated the anti-fibrotic and anti-inflammatory effects of STAT3 decoy oligodeoxynucleotides (ODN) in hepatocytes and liver fibrosis mouse models. STAT3 decoy ODN were delivered into cells using liposomes and hydrodynamic tail vein injection into 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-fed mice in which liver injury was induced. STAT3 target gene expression changes were verified using qPCR and Western blotting. Liver tissue fibrosis and bile duct proliferation were assessed in animal experiments using staining techniques, and macrophage and inflammatory cytokine distribution was verified using immunohistochemistry. STAT3 decoy ODN reduced fibrosis and inflammatory factors in liver cancer cell lines and DDC-induced liver injury mouse model. These results suggest that STAT3 decoy ODN may effectively treat liver fibrosis and must be clinically investigated.

Current Advances in Corneal Stromal Stem Cell Biology and Therapeutic Applications

Corneal stromal stem cells (CSSCs) are of particular interest in regenerative ophthalmology, offering a new therapeutic target for corneal injuries and diseases. This review provides a comprehensive examination of CSSCs, exploring their anatomy, functions, and role in maintaining corneal integrity. Molecular markers, wound healing mechanisms, and potential therapeutic applications are discussed. Global corneal blindness, especially in more resource-limited regions, underscores the need for innovative solutions. Challenges posed by corneal defects, emphasizing the urgent need for advanced therapeutic interventions, are discussed. The review places a spotlight on exosome therapy as a potential therapy. CSSC-derived exosomes exhibit significant potential for modulating inflammation, promoting tissue repair, and addressing corneal transparency. Additionally, the rejuvenation potential of CSSCs through epigenetic reprogramming adds to the evolving regenerative landscape. The imperative for clinical trials and human studies to seamlessly integrate these strategies into practice is emphasized. This points towards a future where CSSC-based therapies, particularly leveraging exosomes, play a central role in diversifying ophthalmic regenerative medicine.

Unimolecular Cascaded Multienzyme Conjugates Modulate the Microenvironment of Diabetic Wound to Promote Healing

An abnormal microenvironment underlies poor healing in chronic diabetic chronic wounds. However, effectively modulating the microenvironment of the diabetic wound remains a great challenge due to sustained oxidative stress and chronic inflammation. Here, we present a unimolecular enzyme-polymer conjugate that demonstrates excellent multienzymatic cascade activities. The cascaded enzyme conjugates (CECs) were synthesized by grafting poly(N-acryloyl-lysine) (pLAAm) from the glycan moieties of glucose oxidase (GOx) via glycan-initiated polymerization. The resulting CECs exhibited multiple enzymatic properties of GOx, superoxide dismutase mimic, and catalase mimic activities simultaneously. The CECs facilitated the depletion of high blood glucose, ROS scavenging, bacteria-killing, anti-inflammatory effects, and sustained oxygen generation, which restored the microenvironment in diabetic wounds. In vivo results from a diabetic mouse model confirmed the capacity and efficiency of the cascade reaction for diabetic wound healing. Our findings demonstrate that the three-in-one enzyme-polymer conjugates alone can modulate the diabetic microenvironment for wound healing.

Designing Hydrogels for Immunomodulation in Cancer Therapy and Regenerative Medicine

The immune system not only acts as a defense against pathogen and cancer cells, but also plays an important role in homeostasis and tissue regeneration. Targeting immune systems is a promising strategy for efficient cancer treatment and regenerative medicine. Current systemic immunomodulation therapies are usually associated with low persistence time, poor targeting to action sites, and severe side effects. Due to their extracellular matrix-mimetic nature, tunable properties and diverse bioactivities, hydrogels are intriguing platforms to locally deliver immunomodulatory agents and cells, as well as provide an immunomodulatory microenvironment to recruit, activate, and expand host immune cells. In this review, the design considerations, including polymer backbones, crosslinking mechanisms, physicochemical nature, and immunomodulation-related components, of the hydrogel platforms, are focused on. The immunomodulatory effects and therapeutic outcomes in cancer therapy and tissue regeneration of different hydrogel systems are emphasized, including hydrogel depots for delivery of immunomodulatory agents, hydrogel scaffolds for cell delivery, and immunomodulatory hydrogels depending on the intrinsic properties of materials. Finally, the remained challenges in current systems and future development of immunomodulatory hydrogels are discussed.

Needle biopsy accelerates pro-metastatic changes and systemic dissemination in breast cancer: Implications for mortality by surgery delay

Increased breast cancer (BC) mortality risk posed by delayed surgical resection of tumor after diagnosis is a growing concern, yet the underlying mechanisms remain unknown. Our cohort analyses of early-stage BC patients reveal the emergence of a significantly rising mortality risk when the biopsy-to-surgery interval was extended beyond 53 days. Additionally, histology of post-biopsy tumors shows prolonged retention of a metastasis-permissive wound stroma dominated by M2-like macrophages capable of promoting cancer cell epithelial-to-mesenchymal transition and angiogenesis. We show that needle biopsy promotes systemic dissemination of cancer cells through a mechanism of sustained activation of the COX-2/PGE2/EP2 feedforward loop, which favors M2 polarization and its associated pro-metastatic changes but are abrogated by oral treatment with COX-2 or EP2 inhibitors in estrogen-receptor-positive (ER+) syngeneic mouse tumor models. Therefore, we conclude that needle biopsy of ER+ BC provokes progressive pro-metastatic changes, which may explain the mortality risk posed by surgery delay after diagnosis.

Biomimetic Nanozyme-Decorated Hydrogels with H2O2-Activated Oxygenation for Modulating Immune Microenvironment in Diabetic Wound

Diabetic foot ulcers (DFUs) remain a devastating threat to human health. While hydrogels are promising systems for DFU-based wound management, their effectiveness is often hindered by the immune response and hostile wound microenvironment associated with the uncontrollable accumulation of reactive oxygen species and hypoxia. Here, we develop a therapeutic wound dressing using a biomimetic hydrogel system with the decoration of catalase-mimic nanozyme, namely, MnCoO@PDA/CPH. The hydrogel can be designed to match the mechanical and electrical cues of skins simultaneously with H2O2-activated oxygenation ability. As a proof of concept, DFU-based rat models are created to validate the therapeutic efficacy of the MnCoO@PDA/CPH hydrogel in vivo. The results indicate that the developed hydrogel can promote DFU healing and improve the quality of the healed wound as featured by alleviated proinflammatory, increased re-epithelialization, highly ordered collagen deposition, and functional blood vessel growth.

A system for bioelectronic delivery of treatment directed toward wound healing

The development of wearable bioelectronic systems is a promising approach for optimal delivery of therapeutic treatments. These systems can provide continuous delivery of ions, charged biomolecules, and an electric field for various medical applications. However, rapid prototyping of wearable bioelectronic systems for controlled delivery of specific treatments with a scalable fabrication process is challenging. We present a wearable bioelectronic system comprised of a polydimethylsiloxane (PDMS) device cast in customizable 3D printed molds and a printed circuit board (PCB), which employs commercially available engineering components and tools throughout design and fabrication. The system, featuring solution-filled reservoirs, embedded electrodes, and hydrogel-filled capillary tubing, is assembled modularly. The PDMS and PCB both contain matching through-holes designed to hold metallic contact posts coated with silver epoxy, allowing for mechanical and electrical integration. This assembly scheme allows us to interchange subsystem components, such as various PCB designs and reservoir solutions. We present three PCB designs: a wired version and two battery-powered versions with and without onboard memory. The wired design uses an external voltage controller for device actuation. The battery-powered PCB design uses a microcontroller unit to enable pre-programmed applied voltages and deep sleep mode to prolong battery run time. Finally, the battery-powered PCB with onboard memory is developed to record delivered currents, which enables us to verify treatment dose delivered. To demonstrate the functionality of the platform, the devices are used to deliver H[Formula: see text] in vivo using mouse models and fluoxetine ex vivo using a simulated wound environment. Immunohistochemistry staining shows an improvement of 35.86% in the M1/M2 ratio of H[Formula: see text]-treated wounds compared with control wounds, indicating the potential of the platform to improve wound healing.

Annexin A12-26 hydrogel improves healing properties in an experimental skin lesion after induction of type 1 diabetes

Diabetes mellitus (DM) is characterized by metabolic alterations that involve defects in the secretion and/or action of insulin, being responsible for several complications, such as impaired healing. Studies from our research group have shown that annexin A1 protein (AnxA1) is involved in the regulation of inflammation and cell proliferation. In light of these findings, we have developed a new technology and evaluated its effect on a wound healing in vivo model using type 1 diabetes (T1DM)-induced mice. We formulated a hydrogel containing AnxA12-26 using defined parameters such as organoleptic characteristics, pH, UV-vis spectroscopy and cytotoxicity assay. UV-vis spectroscopy confirmed the presence of the associated AnxA12-26 peptide in the three-dimensional hydrogel matrix, while the in vitro cytotoxicity assay showed excellent biocompatibility. Mice showed increased blood glucose levels, confirming the efficacy of streptozotocin (STZ) to induce T1DM. Treatment with AnxA12-26 hydrogel showed to improve diabetic wound healing, defined as complete re-epithelialization and tissue remodeling, with reduction of inflammatory infiltrate in diabetic animals. We envisage that the AnxA12-26 hydrogel, with its innovative composition and formulation be efficient on improving diabetic healing and contributing on the expansion of the therapeutic arsenal to treat diabetic wounds, at a viable cost.

Arrhenius-model-based degradable oligourethane hydrogels for controlled growth factor release

Biodegradable hydrogels are growing in demand to enable the delivery of biomolecules (e.g. growth factors) for regenerative medicine. This research investigated the resorption of an oligourethane/polyacrylic acid hydrogel, a biodegradable hydrogel which supports tissue regeneration. The Arrhenius model was used to characterize the resorption of the polymeric gels in relevant in vitro conditions, and the Flory-Rehner equation was used to correlate the volumetric swelling ratio with the extent of degradation. The study found that the swelling rate of the hydrogel follows the Arrhenius model at elevated temperatures, estimating degradation time in saline solution at 37°C to be between 5 and 13 months, serving as a preliminary approximation of degradation in vivo. The degradation products had low cytotoxicity towards endothelial cells, and the hydrogel supported stromal cell proliferation. Additionally, the hydrogels were able to release growth factors and maintain the biomolecules' bioactivity towards cell proliferation. The study of the vascular endothelial growth factor (VEGF) release from the hydrogel used a diffusion process model, showing that the electrostatic attraction between VEGF and the anionic hydrogel allowed for controlled and sustained VEGF release over three weeks. In a rat subcutaneous implant model, a selected hydrogel with desired degradation rates exhibited minimal foreign body response and supported M2a macrophage phenotype, and vascularization. The low M1 and high M2a macrophage phenotypes within the implants were associated with tissue integration. This research supports the use of oligourethane/polyacrylic acid hydrogels as a promising material for delivering growth factors and supporting tissue regeneration. STATEMENT OF SIGNIFICANCE: There is a need for degradable elastomeric hydrogels that can support the formation of soft tissues and minimize long-term foreign body responses. An Arrhenius model was used to estimate the relative breakdown of hydrogels, in-vitro. The results demonstrate that hydrogels made from a combination of poly(acrylic acid) and oligo-urethane diacrylates can be designed to resorb over defined periods ranging from months to years depending on the chemical formulation prescribed by the model. The hydrogel formulations also provided for different release profiles of growth factors, relevant to tissue regeneration. In-vivo, these hydrogels had minimal inflammatory effects and showed evidence of integration into the surrounding tissue. The hydrogel approach can help the field design a broader range of biomaterials for tissue regeneration.

Nanosilicate-functionalized nanofibrous membrane facilitated periodontal regeneration potential by harnessing periodontal ligament cell-mediated osteogenesis and immunomodulation

Although various new biomaterials have enriched the methods for periodontal regeneration, their efficacy is still controversial, and the regeneration of damaged support tissue in the periodontium remains challenging. Laponite (LAP) nanosilicate is a layered two-dimensional nanoscale, ultrathin nanomaterial with a unique structure and brilliant biocompatibility and bioactivity. This study aimed to investigate the effects of nanosilicate-incorporated PCL (PCL/LAP) nanofibrous membranes on periodontal ligament cells (PDLCs) in vitro and periodontal regeneration in vivo. A PCL/LAP nanofibrous membrane was fabricated by an electrospinning method. The characterization of PCL/LAP nanofibrous membrane were determined by scanning electron microscopy (SEM), energy dispersive spectrum of X-ray (EDS), inductively coupled plasma mass spectrometry (ICP-MS) and tensile test. The proliferation and osteogenic differentiation of PDLCs on the PCL/LAP nanofibrous membrane were evaluated. A PDLCs and macrophage coculture system was used to explore the immunomodulatory effects of the PCL/LAP nanofibrous membrane. PCL/LAP nanofibrous membrane was implanted into rat calvarial and periodontal defects, and the regenerative potential was evaluated by microcomputed topography (micro-CT) and histological analysis. The PCL/LAP nanofibrous membrane showed good biocompatibility and bioactivity. It enhanced the proliferation and osteogenic differentiation of PDLCs. The PCL/LAP nanofibrous membrane also stimulated anti-inflammatory and pro-remodeling N2 neutrophil formation, regulated inflammatory responses and induced M2 macrophage polarization by orchestrating the immunomodulatory effects of PDLCs. The PCL/LAP nanofibrous membrane promoted rat calvarial defect repair and periodontal regeneration in vivo. LAP nanosilicate-incorporated PCL membrane is capable of mediating osteogenesis and immunomodulation of PDLCs in vitro and accelerating periodontal regeneration in vivo. It could be a promising biomaterial for periodontal regeneration therapy.

RNF41 orchestrates macrophage-driven fibrosis resolution and hepatic regeneration

Hepatic inflammation is a common trigger of chronic liver disease. Macrophage activation is a predictive parameter for survival in patients with cirrhosis. Ring finger protein 41 (RNF41) negatively regulates proinflammatory cytokines and receptors; however, the precise involvement of macrophage RNF41 in liver cirrhosis remains unknown. Here, we sought to understand how RNF41 dictates macrophage fate in hepatic fibrosis and repair within the inflammatory milieu. We found that RNF41 expression is down-regulated in CD11b+ macrophages recruited to mouse fibrotic liver and to patient cirrhotic liver regardless of cirrhosis etiology. Prolonged inflammation with TNF-α progressively reduced macrophage RNF41 expression. We designed a macrophage-selective gene therapy with dendrimer-graphite nanoparticles (DGNPs) to explore the influence of macrophage RNF41 restoration and depletion in liver fibrosis and regeneration. RNF41 expression induced in CD11b+ macrophages by DGNP-conjugated plasmids ameliorated liver fibrosis, reduced liver injury, and stimulated hepatic regeneration in fibrotic mice with or without hepatectomy. This therapeutic effect was mainly mediated by the induction of insulin-like growth factor 1. Conversely, depletion of macrophage RNF41 worsened inflammation, fibrosis, hepatic damage, and survival. Our data reveal implications of macrophage RNF41 in the control of hepatic inflammation, fibrosis, and regeneration and provide a rationale for therapeutic strategies in chronic liver disease and potentially other diseases characterized by inflammation and fibrosis.

Zfp697 is an RNA-binding protein that regulates skeletal muscle inflammation and regeneration

Muscular atrophy is a mortality risk factor that happens with disuse, chronic disease, and aging. Recovery from atrophy requires changes in several cell types including muscle fibers, and satellite and immune cells. Here we show that Zfp697/ZNF697 is a damage-induced regulator of muscle regeneration, during which its expression is transiently elevated. Conversely, sustained Zfp697 expression in mouse muscle leads to a gene expression signature of chemokine secretion, immune cell recruitment, and extracellular matrix remodeling. Myofiber-specific Zfp697 ablation hinders the inflammatory and regenerative response to muscle injury, compromising functional recovery. We uncover Zfp697 as an essential interferon gamma mediator in muscle cells, interacting primarily with ncRNAs such as the pro-regenerative miR-206. In sum, we identify Zfp697 as an integrator of cell-cell communication necessary for tissue regeneration.

Composite microgranular scaffolds with surface modifications for improved initial osteoblastic cell proliferation

Polyester-based granular scaffolds are a potent material for tissue engineering due to their porosity, controllable pore size, and potential to be molded into various shapes. Additionally, they can be produced as composite materials, e.g., mixed with osteoconductive β-tricalcium phosphate or hydroxyapatite. Such polymer-based composite materials often happen to be hydrophobic, which disrupts cell attachment and decreases cell growth on the scaffold, undermining its primary function. In this work, we propose the experimental comparison of three modification techniques for granular scaffolds to increase their hydrophilicity and cell attachment. Those techniques include atmospheric plasma treatment, polydopamine coating, and polynorepinephrine coating. Composite polymer/β-tricalcium phosphate granules have been produced in a solution-induced phase separation (SIPS) process using commercially available biomedical polymers: poly(lactic acid), poly(lactic-co-glycolic acid), and polycaprolactone. We used thermal assembly to prepare cylindrical scaffolds from composite microgranules. Atmospheric plasma treatment, polydopamine coating, and polynorepinephrine coating showed similar effects on polymer composites' hydrophilic and bioactive properties. All modifications significantly increased human osteosarcoma MG-63 cell adhesion and proliferation in vitro compared to cells cultured on unmodified materials. In the case of polycaprolactone/β-tricalcium phosphate scaffolds, modifications were the most necessary, as unmodified polycaprolactone-based material disrupted the cell attachment. Modified polylactide/β-tricalcium phosphate scaffold supported excellent cell growth and showed ultimate compressive strength exceeding this of human trabecular bone. This suggests that all investigated modification techniques can be used interchangeably for increasing wettability and cell attachment properties of various scaffolds for medical applications, especially those with high surface and volumetric porosity, like granular scaffolds.

The RNA editor ADAR2 promotes immune cell trafficking by enhancing endothelial responses to interleukin-6 during sterile inflammation

Immune cell trafficking constitutes a fundamental component of immunological response to tissue injury, but the contribution of intrinsic RNA nucleotide modifications to this response remains elusive. We report that RNA editor ADAR2 exerts a tissue- and stress-specific regulation of endothelial responses to interleukin-6 (IL-6), which tightly controls leukocyte trafficking in IL-6-inflamed and ischemic tissues. Genetic ablation of ADAR2 from vascular endothelial cells diminished myeloid cell rolling and adhesion on vascular walls and reduced immune cell infiltration within ischemic tissues. ADAR2 was required in the endothelium for the expression of the IL-6 receptor subunit, IL-6 signal transducer (IL6ST; gp130), and subsequently, for IL-6 trans-signaling responses. ADAR2-induced adenosine-to-inosine RNA editing suppressed the Drosha-dependent primary microRNA processing, thereby overwriting the default endothelial transcriptional program to safeguard gp130 expression. This work demonstrates a role for ADAR2 epitranscriptional activity as a checkpoint in IL-6 trans-signaling and immune cell trafficking to sites of tissue injury.

Cellular and Molecular Mechanisms Underly the Combined Treatment of Fasudil and Bone Marrow Derived-Neuronal Stem Cells in a Parkinson's Disease Mouse Model

Bone marrow-derived neural stem cells (BM-NSCs) have shed light on novel therapeutic approaches for PD with the potential to halt or even reverse disease progression. Various strategies have been developed to promote therapeutic efficacy via optimizing implanted cells and the microenvironment of transplantation in the central nervous system (CNS). This current study further proved that the combination of fasudil, a Rho-kinase inhibitor, and BM-NSCs exhibited a synergetic effect on restoring neuron loss in the MPTP-PD mice model. It simultaneously unveiled cellular mechanisms underlying synergistic neuron-protection effects of fasudil and BM-NSCs, which included promoting the proliferation, and migration of endogenous NSCs, and contributing to microglia shift into the M2 phenotype. Corresponding molecular mechanisms were observed, including the inhibition of inflammatory responses, the elevation of neurotrophic factors, and the induction of WNT/β-catenin and PI3K/Akt/mTOR signaling pathways. Our study provides evidence for the co-intervention of BM-NSCs and fasudil as a promising therapeutic method with enhanced efficacy in treating neurodegenerative diseases.

Microneedles for in situ tissue regeneration

Tissue injury is a common clinical problem, which may cause great burden on patients' life. It is important to develop functional scaffolds to promote tissue repair and regeneration. Due to their unique composition and structure, microneedles have attracted extensive attention in various tissues regeneration, including skin wound, corneal injury, myocardial infarction, endometrial injury, and spinal cord injury et al. Microneedles with micro-needle structure can effectively penetrate the barriers of necrotic tissue or biofilm, therefore improving the bioavailability of drugs. The use of microneedles to deliver bioactive molecules, mesenchymal stem cells, and growth factors in situ allows for targeted tissue and better spatial distribution. At the same time, microneedles can also provide mechanical support or directional traction for tissue, thus accelerating tissue repair. This review summarized the research progress of microneedles for in situ tissue regeneration over the past decade. At the same time, the shortcomings of existing researches, future research direction and clinical application prospect were also discussed.

PCL and DMSO2 Composites for Bio-Scaffold Materials

Polycaprolactone (PCL) has been one of the most popular biomaterials in tissue engineering due to its relatively low melting temperature, excellent thermal stability, and cost-effectiveness. However, its low cell attraction, low elastic modulus, and long-term degradation time have limited its application in a wide range of scaffold studies. Dimethyl sulfone (DMSO₂) is a stable and non-hazardous organosulfur compound with low viscosity and high surface tension. PCL and DMSO₂ composites may overcome the limitations of PCL as a biomaterial and tailor the properties of biocomposites. In this study, PCL and DMSO₂ composites were investigated as a new bio-scaffold material to increase hydrophilicity and mechanical properties and tailor degradation properties in vitro. PCL and DMSO₂ were physically mixed with 10, 20, and 30 wt% of DMSO₂ to evaluate thermal, hydrophilicity, mechanical, and degradation properties of the composites. The water contact angle of the composites for hydrophilicity decreased by 15.5% compared to pure PCL. The experimental results showed that the mechanical and degradation properties of PCL and DMSO₂ were better than those of pure PCL, and the properties can be tuned by regulating DMSO2 concentration in the PCL matrix. The elastic modulus of the composite with 30 wt% of DMSO2 showed 532 MPa, and its degradation time was 18 times faster than that of PCL.

LIFR recruits HGF-producing neutrophils to promote liver injury repair and regeneration

The molecular links between tissue repair and tumorigenesis remain elusive. Here, we report that loss of the liver tumor suppressor Lifr in mouse hepatocytes impairs the recruitment and activity of reparative neutrophils, resulting in the inhibition of liver regeneration after partial hepatectomy or toxic injuries. On the other hand, overexpression of LIFR promotes liver repair and regeneration after injury. Interestingly, LIFR deficiency or overexpression does not affect hepatocyte proliferation ex vivo or in vitro . In response to physical or chemical damage to the liver, LIFR from hepatocytes promotes the secretion of the neutrophil chemoattractant CXCL1 (which binds CXCR2 to recruit neutrophils) and cholesterol in a STAT3-dependent manner. Cholesterol, in turn, acts on the recruited neutrophils to secrete hepatocyte growth factor (HGF) to accelerate hepatocyte proliferation and regeneration. Altogether, our findings reveal a LIFR-STAT3- CXCL1-CXCR2 axis and a LIFR-STAT3-cholesterol-HGF axis that mediate hepatic damage- induced crosstalk between hepatocytes and neutrophils to repair and regenerate the liver.

Fabrication of a New Hyaluronic Acid/Gelatin Nanocomposite Hydrogel Coating on Titanium-Based Implants for Treating Biofilm Infection and Excessive Inflammatory Response

Persistent inflammation caused by implant-associated biofilm infections has emerged as a significant clinical issue. While many methods have been developed to give implants great anti-biofilm benefits, the post-inflammatory microenvironment is frequently disregarded. Oxidative stress (OS) due to excessive reactive oxygen species (ROS) is considered to be one of the specific physiological signals of the inflammation microenvironment. Herein, ZIF-90-Bi-CeO₂ nanoparticles (NPs) were incorporated into a Schiff-base chemically crosslinked hydrogel composed of aldehyde-based hyaluronic acid and gelatin. Through chemical crosslinking between polydopamine and gelatin, the hydrogel coating adhered to the Ti substrate. The modified Ti substrate gained multimodal antibacterial and anti-biofilm functions, which were attributed to the photothermal effect of Bi NPs, and the release of Zn ions and CeO₂ NPs. Notably, CeO₂ NPs endowed the system with dual-enzyme (SOD- and CAT-like) catalytic activities. In a rat implant-associated infection (IAI) model, the dual-functional hydrogel had a biofilm-removal ability and regulated OS and inflammatory responses to facilitate osseointegration. The photothermal therapy combined with a host inflammation-microenvironment regulation strategy might provide a novel treatment for biofilm infection and the accompanying excessive inflammation.

Nanomaterials and nanomaterials-based drug delivery to promote cutaneous wound healing

Various factors could damage the structure and integrity of skin to cause wounds. Nonhealing or chronic wounds seriously affect the well-being of patients and bring heavy burdens to the society. The past few decades have witnessed application of numerous nanomaterials to promote wound healing. Owing to the unique physicochemical characteristics at nanoscale, nanomaterials-based therapy has been regarded as a potential approach to promote wound healing. In this review, we first overview the wound categories, wound healing process and critical influencing factors. Then applications of nanomaterials with intrinsic therapeutic effect and nanomaterials-based drug delivery systems to promote wound healing are addressed in detail. Finally, current limitations and future perspectives of nanomaterials in wound healing are discussed.

The Role of Myofibroblasts in Physiological and Pathological Tissue Repair

Myofibroblasts are the construction workers of wound healing and repair damaged tissues by producing and organizing collagen/extracellular matrix (ECM) into scar tissue. Scar tissue effectively and quickly restores the mechanical integrity of lost tissue architecture but comes at the price of lost tissue functionality. Fibrotic diseases caused by excessive or persistent myofibroblast activity can lead to organ failure. This review defines myofibroblast terminology, phenotypic characteristics, and functions. We will focus on the central role of the cell, ECM, and tissue mechanics in regulating tissue repair by controlling myofibroblast action. Additionally, we will discuss how therapies based on mechanical intervention potentially ameliorate wound healing outcomes. Although myofibroblast physiology and pathology affect all organs, we will emphasize cutaneous wound healing and hypertrophic scarring as paradigms for normal tissue repair versus fibrosis. A central message of this review is that myofibroblasts can be activated from multiple cell sources, varying with local environment and type of injury, to either restore tissue integrity and organ function or create an inappropriate mechanical environment.

Unsaturated or saturated dietary fat-mediated steatosis impairs hepatic regeneration following partial hepatectomy in mice

BACKGROUND

Partial hepatectomy is a preferred treatment option for many patients with hepatocellular carcinoma however, pre-existing pathological abnormalities originating from hepatic steatosis can alter the decision to perform surgery or postoperative outcomes as a consequence of the impact steatosis has on liver regeneration.

AIM

The aim of this study was to investigate the role of a saturated or unsaturated high fat diet-mediated steatosis on liver regeneration following partial hepatectomy.

METHODS

Mice were fed a low-fat control diet (CD, 13% fat), lard-based unsaturated (LD, 60% fat) or milk-based saturated high fat diet (MD, 60% fat) for 16 weeks at which time partial hepatectomy (approx. 70% resection) was performed. At days-2 and 7 post hepatectomy, one hour prior to euthanization, mice were injected with 5-bromo-2'-deoxyuridine in order to monitor hepatic regeneration. Serum was collected and assessed for levels of ALT and AST. Resected and regenerated liver tissue were examined for inflammation-indicative markers employing RT-PCR, Western blots, and histological methods.

RESULTS

Mice fed LD or MD exhibited higher NAFLD scores, increased expression of inflammatory cytokines, neutrophil infiltration, macrophage accumulation, increased apoptosis, and elevated levels of serum ALT and AST activities, a decrease in the number of BrdU-incorporated-hepatocytes in the regenerated livers compared to the mice fed CD. Mice fed MD showed significantly lower percent of BrdU-incorporated hepatocytes and a higher trend of inflammation compared to the mice fed LD.

CONCLUSION

A diet rich in saturated or unsaturated fat results in NASH with decreased hepatic regeneration however unsaturated fat diet cause lower inflammation and higher regeneration than the saturated fat diet following partial hepatectomy in mice.