PGC1α-Inducing Senomorphic Nanotherapeutics Functionalized with NKG2D-Overexpressing Cell Membranes for Intervertebral Disc Degeneration.

Cellular senescence is a significant contributor to intervertebral disc aging and degeneration. However, the application of senotherapies, such as senomorphics targeting senescence markers and the senescence-associated secretory phenotype (SASP), remains limited due to challenges in precise delivery. Given that the natural killer group 2D (NKG2D) ligands are increased on the surface of senescent nucleus pulposus (NP) cells, the NKG2D-overexpressing NP cell membranes (NNPm) are constructed, which is expected to achieve a dual targeting effect toward senescent NP cells based on homologous membrane fusion and the NKG2D-mediated immunosurveillance mechanism. Then, mesoporous silica nanoparticles carrying a peroxisome proliferator-activated receptor-É£ coactivator 1α (PGC1α)inducer (SP) are coated with NNPm (SP@NNPm) and it is found that SP@NNPm selectively targets senescent NP cells, and the SP cores exhibit pH-responsive drug release. Moreover, SP@NNPm effectively induces PGC1α-mediated mitochondrial biogenesis and mitigates senescence-associated markers induced by oxidative stress and the SASP, thereby alleviating puncture-induced senescence and disc degeneration. This dual-targeting nanotherapeutic system represents a novel approach to delivery senomorphics for disc degeneration treatment.

Identification of the C1qDC gene family in grass carp (Ctenopharyngodon idellus) and the response of C1qA, C1qB, and C1qC to GCRV infection in vivo and in vitro.

Proteins from the C1q domain-containing (C1qDC) family recognize self-, non-self-, and altered-self ligands and serves as an initiator molecule for the classical complement pathway as well as recognizing immune complexes. In this study, C1qDC gene family members were identified and analyzed in grass carp (Ctenopharyngodon idellus). Members of the C1q subfamily were cloned, and their response to infection with the grass carp virus was investigated. In the grass carp genome, 54 C1qDC genes and 67 isoforms have been identified. Most were located on chromosome 3, with 52 shared zebrafish homologies. Seven substantially differentially expressed C1qDC family genes were identified in the transcriptomes of cytokine-induced killer (CIK) cells infected with grass carp reovirus (GCRV), all of which exhibited sustained upregulation. The opening reading frames of grass carp C1qA, C1qB, and C1qC, belonging to the C1q subfamily, were determined to be 738, 732, and 735 base pairs, encoding 245, 243, and 244 amino acids with molecular weights of 25.81 kDa, 25.63 kDa and 26.16 kDa, respectively. Three genes were detected in the nine collected tissues, and their expression patterns were similar, with the highest expression levels observed in the spleen. In vivo after GCRV infection showed expression trends of C1qA, C1qB, and C1qC in the liver, spleen, and kidney. An N-type pattern in the liver and kidney was characterized by an initial increase followed by a decrease, with the highest expression occurring during the recovering period, and a V-type pattern in the spleen with the lowest expression levels during the death period. In vitro, after GCRV infection showed expression trends of C1qA, C1qB, and C1qC, and this gradually increased within the first 24 h, with a notable increase observed at the 24 h time point. After CIK cells incubation with purified recombinant proteins, rC1qA, rC1qB, and rC1qC for 3 h, followed by GCRV inoculation, the GCRV replication indicated that rC1qC exerted a substantial inhibitory effect on viral replication in CIK cells after 24 h of GCRV inoculation. These findings offer valuable insights into the structure, evolution, and function of the C1qDC family genes and provide a foundational understanding of the immune function of C1q in grass carp.

Roles of organokines in intervertebral disc homeostasis and degeneration.

The intervertebral disc is not isolated from other tissues. Recently, abundant research has linked intervertebral disc homeostasis and degeneration to various systemic diseases, including obesity, metabolic syndrome, and diabetes. Organokines are a group of diverse factors named for the tissue of origin, including adipokines, osteokines, myokines, cardiokines, gastrointestinal hormones, and hepatokines. Through endocrine, paracrine, and autocrine mechanisms, organokines modulate energy homeostasis, oxidative stress, and metabolic balance in various tissues to mediate cross-organ communication. These molecules are involved in the regulation of cellular behavior, inflammation, and matrix metabolism under physiological and pathological conditions. In this review, we aimed to summarize the impact of organokines on disc homeostasis and degeneration and the underlying signaling mechanism. We focused on the regulatory mechanisms of organokines to provide a basis for the development of early diagnostic and therapeutic strategies for disc degeneration.

Kongensin a attenuates intervertebral disc degeneration by inhibiting TAK1-mediated PANoptosis of nucleus pulposus cells.

Low back pain (LBP) is most commonly caused by intervertebral disc degeneration (IVDD). Pyroptosis, apoptosis, and necroptosis are crucial in IVDD pathogenesis; however, possible simultaneous occurrence in IVDD and co-regulation between the pathways and the regulatory mechanisms have not been investigated. PANoptosis is a regulated cell death (RCD) pathway with the key characteristics of pyroptosis, apoptosis, and necroptosis. This study revealed that tert-butyl hydroperoxide (TBHP) altered the expression of key proteins involved in PANoptosis in nucleus pulposus cells (NPCs). Furthermore, the natural product Kongensin A (KA), which has potential anti-necrotic and anti-inflammatory properties, inhibited PANoptosis. TAK1, often referred to as mitogen-activated protein kinase kinase kinase 7 (Map3k7), is a key regulator of innate immunity, cell death, inflammation, and cellular homeostasis; however, the physiological roles and regulatory mechanisms underlying IVDD remain unclear. In this study, we discovered that KA can upregulate TAK1 expression in NPCs, -which inhibits PANoptosis by suppressing oxidative stress. In conclusion, our results suggest that KA inhibits PANoptosis and delays IVDD progression in NPCs by upregulating TAK1 expression to maintain mitochondrial redox balance. Consequently, targeting TAK1 may be a promising therapeutic approach for IVDD therapy.

TBK1 upregulates the interferon response against virus by the TBK1-IRF3/7 axis in yellow catfish (Pelteobagrus fulvidraco).

Yellow catfish (Pelteobagrus fulvidraco) is an important economic species of freshwater fish, widely distributed in China. Recently, viral diseases of yellow catfish have been identified in Chian (Hubei province), arising more attention to the viral immunity in P. fulvidraco. Tumor necrosis factor (TNF) receptor-associated factor NF-κB activator (TANK)-binding kinase 1 (TBK1) plays an essential role in IFN production and innate antiviral immunity. In the present study, we characterized the P. fulvidraco TBK1 (PfTBK1) and reported its function in interferon response. The full-length open reading frame (ORF) is 2184 bp encoding a protein with 727 amino acids, which is composed of four conserved domains, including KD, ULD, CCD1, and CCD2, similar to TBK1 in other species. Pftbk1 was widely expressed in all detected tissues by qPCR and was not inducible by the spring viremia of carp virus (SVCV), a single-strand RNA virus. In addition, the cellular distribution indicated that PfTBK1 was only located in the cytoplasm. Moreover, PfTBK1 induced strong IFN promoter activities through the Jak-stat pathway, and PfTBK1 interacted with and significantly phosphorylated IFN regulatory factor 3/7 (IRF3/7) in P. fulvidraco, promoting the nuclear translocation of pfIRF3 and PfIRF7, and PfTBK1 upregulated IFN response by PfTBK1-PfIRF3/7 axis. Above all, PfTBK1 triggered IFN response and strongly inhibited the replication of SVCV in EPC cells through induction of IFN downstream IFN-stimulated genes (ISGs). Summarily, this work reveals that PfTBK1 plays a positive regulatory role in IFN induction through the TBK1-IRF3/7 axis, laying a foundation for further exploring the molecular mechanism of the antiviral process in P. fulvidraco.

Traumatic brain injury stimulates sympathetic tone-mediated bone marrow myelopoiesis to favor fracture healing.

Traumatic brain injury (TBI) accelerates fracture healing, but the underlying mechanism remains largely unknown. Accumulating evidence indicates that the central nervous system (CNS) plays a pivotal role in regulating immune system and skeletal homeostasis. However, the impact of CNS injury on hematopoiesis commitment was overlooked. Here, we found that the dramatically elevated sympathetic tone accompanied with TBI-accelerated fracture healing; chemical sympathectomy blocks TBI-induced fracture healing. TBI-induced hypersensitivity of adrenergic signaling promotes the proliferation of bone marrow hematopoietic stem cells (HSCs) and swiftly skews HSCs toward anti-inflammation myeloid cells within 14 days, which favor fracture healing. Knockout of ß3- or ß2-adrenergic receptor (AR) eliminate TBI-mediated anti-inflammation macrophage expansion and TBI-accelerated fracture healing. RNA sequencing of bone marrow cells revealed that Adrb2 and Adrb3 maintain proliferation and commitment of immune cells. Importantly, flow cytometry confirmed that deletion of ß2-AR inhibits M2 polarization of macrophages at 7th day and 14th day; and TBI-induced HSCs proliferation was impaired in ß3-AR knockout mice. Moreover, ß3- and ß2-AR agonists synergistically promote infiltration of M2 macrophages in callus and accelerate bone healing process. Thus, we conclude that TBI accelerates bone formation during early stage of fracture healing process by shaping the anti-inflammation environment in the bone marrow. These results implicate that the adrenergic signals could serve as potential targets for fracture management.

Enhanced growth performance of abi5 plants under high salt and nitrate is associated with reduced nitric oxide levels.

Numerous environmental stresses have a significant impact on plant growth and development. By 2050, it is anticipated that high salinity will destroy more than fifty percent of the world's agricultural land. Understanding how plants react to the excessive use of nitrogen fertilizers and salt stress is crucial for enhancing crop yield. However, the effect of excessive nitrate treatment on plant development is disputed and poorly understood; so, we evaluated the effect of excessive nitrate supply and high salinity on abi5 plant growth performance. We demonstrated that abi5 plants are tolerant to the harmful environmental conditions of excessive nitrate and salt. abi5 plants have lower amounts of endogenous nitric oxide than Arabidopsis thaliana Columbia-0 plants due to their decreased nitrate reductase activity, caused by a decrease in the transcript level of NIA2, a gene encoding nitrate reductase. Nitric oxide appeared to have a critical role in reducing the salt stress tolerance of plants, which was diminished by an excess of nitrate. Discovering regulators such as ABI5 that can modulate nitrate reductase activity and comprehending the molecular activities of these regulators are crucial for the application of gene-editing techniques. This would result in the appropriate buildup of nitric oxide to increase the production of crops subjected to a variety of environmental stresses.

Peptide chain release factor DIG8 regulates plant growth by affecting ROS-mediated sugar transportation in Arabidopsis thaliana.

Chloroplasts have important roles in photosynthesis, stress sensing and retrograde signaling. However, the relationship between chloroplast peptide chain release factor and ROS-mediated plant growth is still unclear. In the present study, we obtained a loss-of-function mutant dig8 by EMS mutation. The dig8 mutant has few lateral roots and a pale green leaf phenotype. By map-based cloning, the DIG8 gene was located on AT3G62910, with a point mutation leading to amino acid substitution in functional release factor domain. Using yeast-two-hybrid and BiFC, we confirmed DIG8 protein was characterized locating in chloroplast by co-localization with plastid marker and interacting with ribosome-related proteins. Through observing by transmission electron microscopy, quantifying ROS content and measuring the transport efficiency of plasmodesmata in dig8 mutant, we found that abnormal thylakoid stack formation and chloroplast dysfunction in the dig8 mutant caused increased ROS activity leading to callose deposition and lower PD permeability. A local sugar supplement partially alleviated the growth retardation phenotype of the mutant. These findings shed light on chloroplast peptide chain release factor-affected plant growth by ROS stress.

Characterizing the tumor microenvironment at the single-cell level reveals a novel immune evasion mechanism in osteosarcoma.

The immune microenvironment extensively participates in tumorigenesis as well as progression in osteosarcoma (OS). However, the landscape and dynamics of immune cells in OS are poorly characterized. By analyzing single-cell RNA sequencing (scRNA-seq) data, which characterize the transcription state at single-cell resolution, we produced an atlas of the immune microenvironment in OS. The results suggested that a cluster of regulatory dendritic cells (DCs) might shape the immunosuppressive microenvironment in OS by recruiting regulatory T cells. We also found that major histocompatibility complex class I (MHC-I) molecules were downregulated in cancer cells. The findings indicated a reduction in tumor immunogenicity in OS, which can be a potential mechanism of tumor immune escape. Of note, CD24 was identified as a novel "don't eat me" signal that contributed to the immune evasion of OS cells. Altogether, our findings provide insights into the immune landscape of OS, suggesting that myeloid-targeted immunotherapy could be a promising approach to treat OS.

Arabidopsis EXTRA-LARGE G PROTEIN 1 (XLG1) functions together with XLG2 and XLG3 in PAMP-triggered MAPK activation and immunity.

Pattern-triggered immunity (PTI) is an essential strategy used by plants to deploy broad-spectrum resistance against pathogen attacks. Heterotrimeric G proteins have been reported to contribute to PTI. Of the three non-canonical EXTRA-LARGE G PROTEINs (XLGs) in Arabidopsis thaliana, XLG2 and XLG3 were shown to positively regulate immunity, but XLG1 was not considered to function in defense, based on the analysis of a weak xlg1 allele. In this study, we characterized the xlg1 xlg2 xlg3 triple knockout mutants generated from an xlg1 knockout allele. The strong xlg1 xlg2 xlg3 triple mutants compromised pathogen-associated molecular pattern (PAMP)-triggered activation of mitogen-activated protein kinases (MAPKs) and resistance to pathogen infection. The three XLGs interacted with MAPK cascade proteins involved in defense signaling, including the MAPK kinase kinases MAPKKK3 and MAPKKK5, the MAPK kinases MKK4 and MKK5, and the MAPKs MPK3 and MPK6. Expressing a constitutively active form of MKK4 restored MAPK activation and partially recovered the compromised disease resistance seen in the strong xlg1 xlg2 xlg3 triple mutant. Furthermore, mutations of all three XLGs largely restored the phenotype of the autoimmunity mutant bak1-interacting receptor-like kinase 1. Our study reveals that all three XLGs function redundantly in PAMP-triggered MAPK activation and plant immunity.

Regulated cell death: Implications for intervertebral disc degeneration and therapy.

As a controllable biological process, regulated cell death (RCD) extensively participates in cellular homeostasis, organismal development, and the pathogenesis of diseases. This review addresses the research gaps by synthesising the findings on the complexity of RCD modes and their role in disc degeneration, and summarises the preclinical strategies to alleviate disc degeneration and promote disc repair by regulating RCD. Background: Intervertebral disc degeneration (IDD) is the major source of chronic low back pain. As a controllable biological process, regulated cell death (RCD) extensively participates in the pathogenesis of IDD. Nevertheless, the initiation and progression of RCD remain unclear, and more importantly, the interaction between different RCD modes during IDD and therapy is far from well understood. Methods: Literature search was performed using "regulated cell death AND intervertebral disc degeneration" in PubMed, Embase, and Web of Science. Meanwhile, relevant findings have been reviewed and quoted. Results: In this review, we discuss the inducing factors of IDD, various modes of RCD in intervertebral disc, the interactions between different RCD modes, as well as the obstacles to achieve disc regeneration. Meanwhile, the research gaps and perspective in studies that targeting RCD are also presented. Conclusion: Increasing evidence demonstrated the presence of different RCD modes in intervertebral disc during the progression of IDD. RCD in the resident disc cells is probably induced by the multiple factors such as abnormal mechanical loading, nutritional imbalance, inflammation microenvironment, circadian rhythm changes, withdraw of hormones, and other biomechanical factors. A better understanding of the fundamental mechanisms and the interactions between different RCD modes might contribute to the rescuing of disc degeneration and development of promising therapeutics. Translational potential statement: The Translational potential of this article. This review aims to demonstrate a better understanding of the fundamental mechanisms governing RCD, which might contribute to the rescuing of disc degeneration and to the development of promising therapeutics in a clinical setting.

Expert consensus on the bone repair strategy for osteoporotic fractures in China.

Osteoporotic fractures, also known as fragility fractures, are prevalent in the elderly and bring tremendous social burdens. Poor bone quality, weak repair capacity, instability, and high failure rate of internal fixation are main characteristics of osteoporotic fractures. Osteoporotic bone defects are common and need to be repaired by appropriate materials. Proximal humerus, distal radius, tibia plateau, calcaneus, and spine are common osteoporotic fractures with bone defect. Here, the consensus from the Osteoporosis Group of Chinese Orthopaedic Association concentrates on the epidemiology, characters, and management strategies of common osteoporotic fractures with bone defect to standardize clinical practice in bone repair of osteoporotic fractures.

Clinical efficacy of different shoulder joint drug injections for rotator cuff injuries: A network meta-analysis.

BACKGROUND: Rotator cuff injury is a common clinical disorder of the musculoskeletal system. It is one of the most common causes of shoulder pain and shoulder joint dysfunction. Intra-articular injection therapy is one of the common conservative treatments for rotator cuff injury in clinical practice, but scholars have been controversial about the different drugs used for injection therapy and their clinical effectiveness, and there is no complete agreement on the choice of different injectables, and the existing original studies are mostly direct comparisons in 1 arm, lacking indirect comparisons, making it difficult to have a clear and comprehensive understanding. OBJECTIVE: A network Meta-analysis was used to comprehensively compare the effectiveness of drug injection therapies for rotator cuff injuries. METHODS: The PubMed, The Cochrane Library, EMbase, Chinese national knowledge infrastructure, Chinese BioMedical Literature on disc, China Science and Technology Journal Database, and Wan-Fang databases were searched for randomized controlled trials on the effectiveness of steroid injections for the comparative treatment of rotator cuff injury for the period April 19, 2013 to April 19, 2022 (the last decade). Two investigators independently screened the literature, extracted data according to inclusion and exclusion criteria, and evaluated the quality of the literature in parallel. Statistical analysis was performed using Stata 16.0 software to compare the differences in efficacy of each treatment measure and rank the efficacy using the ratio and 95% confidence interval (CI) as the effect indicator. RESULTS: 10 RCTs with a total of 861 patients with rotator cuff injury were included, involving 4 therapeutic measures: corticosteroid injection therapy (COR), platelet-rich plasma injection therapy (PRP), Hyaluronic acid injection therapy (HA), and prolotherapy therapy (PRO).Meta-analysis results showed that the ranking results of the 4 therapeutic measures were: corticosteroid injection + hyaluronic acid injection > platelet-rich plasma injection + corticosteroid injection > corticosteroid injection > platelet-rich plasma injection > PRO > platelet-rich plasma injection + hyaluronic acid injection > hyaluronic acid injection. CONCLUSION: we recommend that corticosteroid injections combined with hyaluronic acid injections can be used for the non-surgical conservative clinical management of rotator cuff injuries.

The Plastidial DIG5 Protein Affects Lateral Root Development by Regulating Flavonoid Biosynthesis and Auxin Transport in Arabidopsis.

To reveal the mechanisms underlying root adaptation to drought stress, we isolated and characterized an Arabidopsis mutant, dig5 (drought inhibition of lateral root growth 5), which exhibited increased sensitivity to the phytohormone abscisic acid (ABA) for the inhibition of lateral root growth. The dig5 mutant also had fewer lateral roots under normal conditions and the aerial parts were yellowish with a lower level of chlorophylls. The mutant seedlings also displayed phenotypes indicative of impaired auxin transport, such as abnormal root curling, leaf venation defects, absence of apical hook formation, and reduced hypocotyl elongation in darkness. Auxin transport assays with [3H]-labeled indole acetic acid (IAA) confirmed that dig5 roots were impaired in polar auxin transport. Map-based cloning and complementation assays indicated that the DIG5 locus encodes a chloroplast-localized tRNA adenosine deaminase arginine (TADA) that is involved in chloroplast protein translation. The levels of flavonoids, which are naturally occurring auxin transport inhibitors in plants, were significantly higher in dig5 roots than in the wild type roots. Further investigation showed that flavonoid biosynthetic genes were upregulated in dig5. Introduction of the flavonoid biosynthetic mutation transparent testa 4 (tt4) into dig5 restored the lateral root growth of dig5. Our study uncovers an important role of DIG5/TADA in retrogradely controlling flavonoid biosynthesis and lateral root development. We suggest that the DIG5-related signaling pathways, triggered likely by drought-induced chlorophyll breakdown and leaf senescence, may potentially help the plants to adapt to drought stress through optimizing the root system architecture.

Functional and expression analysis reveals the involvement of integrin αvß3 in antiviral immunity of grass carp (Ctenopharyngodon idella).

Integrins are α-ß heterodimeric cell receptors that can bind the protein components of pathogens, and play crucial roles in mammalian immune responses, but the immune functions mediated by integrins remains largely unknown in teleost fish. In this study, an integrin αvß3 (GCαvß3) originally assembled by αv (GCαv) and ß3 (GCß3) subunits, was identified from a teleost fish grass carp Ctenopharyngodon idella. The pairwise alignment analyses showed that the amino acid sequences of GCαv and GCß3 shared high similarity (75.2-95.1%) and identity (58.6-90.7%) with their homologs from other vertebrates. Both GCαv and GCß3 harbored the conserved protein domains and motifs, and were clustered in fish branch of the phylogenetic tree containing the counterparts from various vertebrates. Co-immunoprecipitation displayed that GCß3 could interact with the grass carp reovirus (GCRV) outer capsid protein VP5. Two incubation experiments revealed that the interaction of GCRV or VP5 proteins with GCß3 could induce the expressions of type I interferons (IFNs) including IFN2 and IFN3 in grass carp ovary cell line. The functional analysis demonstrated that GCαvß3 served as a receptor of viral protein components to be involved in antiviral immunity as human integrin αvß3 did. In addition, both GCαv and GCß3 were significantly upregulated in various tissues of grass carp after GCRV infection. This study might provide fundamental basis for understanding the molecular characteristics and immune functions of GCαvß3, and offer a new insight into the antiviral immune mechanism specific to the integrins in grass carp.

A high-resolution single-molecule sequencing-based Arabidopsis transcriptome using novel methods of Iso-seq analysis.

BACKGROUND: Accurate and comprehensive annotation of transcript sequences is essential for transcript quantification and differential gene and transcript expression analysis. Single-molecule long-read sequencing technologies provide improved integrity of transcript structures including alternative splicing, and transcription start and polyadenylation sites. However, accuracy is significantly affected by sequencing errors, mRNA degradation, or incomplete cDNA synthesis. RESULTS: We present a new and comprehensive Arabidopsis thaliana Reference Transcript Dataset 3 (AtRTD3). AtRTD3 contains over 169,000 transcripts-twice that of the best current Arabidopsis transcriptome and including over 1500 novel genes. Seventy-eight percent of transcripts are from Iso-seq with accurately defined splice junctions and transcription start and end sites. We develop novel methods to determine splice junctions and transcription start and end sites accurately. Mismatch profiles around splice junctions provide a powerful feature to distinguish correct splice junctions and remove false splice junctions. Stratified approaches identify high-confidence transcription start and end sites and remove fragmentary transcripts due to degradation. AtRTD3 is a major improvement over existing transcriptomes as demonstrated by analysis of an Arabidopsis cold response RNA-seq time-series. AtRTD3 provides higher resolution of transcript expression profiling and identifies cold-induced differential transcription start and polyadenylation site usage. CONCLUSIONS: AtRTD3 is the most comprehensive Arabidopsis transcriptome currently. It improves the precision of differential gene and transcript expression, differential alternative splicing, and transcription start/end site usage analysis from RNA-seq data. The novel methods for identifying accurate splice junctions and transcription start/end sites are widely applicable and will improve single-molecule sequencing analysis from any species.

Tunneling Nanotube-Mediated Mitochondrial Transfer Rescues Nucleus Pulposus Cells from Mitochondrial Dysfunction and Apoptosis.

Stem cell-based therapy has been indicated to be beneficial for intervertebral disc regeneration. However, the underlying mechanisms have not been fully identified. The present study showed that bone marrow mesenchymal stem cells (BMSCs) donated mitochondria to adjacent nucleus pulposus cells (NPCs) in a coculture system. The mode of mitochondrial transfer between these cells was intercellular tunneling nanotube (TNT), which acted as a transportation expressway for mitochondria. NPCs acquired additional mitochondria from BMSCs in a concentration-dependent manner after rotenone-induced mitochondrial dysfunction in NPCs. Further research demonstrated that TNT-mediated mitochondrial transfer rescued NPCs from mitochondrial dysfunction and apoptosis, which was indicated by the recovery of the mitochondrial respiratory chain, the increase in mitochondrial membrane potential, and the decreases in reactive oxygen species (ROS) levels and apoptosis rates. Furthermore, Miro1, a critical protein that regulates mitochondrial movement, was knocked down in BMSCs and significantly reduced mitochondrial transfer from BMSCs to NPCs. These results suggested that Miro1 depletion inhibited the rescue of NPCs with mitochondrial dysfunction. Taken together, our data shed light on a novel mechanism by which BMSCs rescue impaired NPCs, providing a concrete foundation to study the critical role of intercellular interactions in disc regeneration.

PCL scaffold combined with rat tail collagen type I to reduce keratocyte differentiation and prevent corneal stroma fibrosis after injury.

The cornea is one of the major refractive eye components and could be easily injured. An ineffective healing of corneal stromal wound may cause fibrosis and even loss of vision. Therefore, it is pivotal to prevent corneal fibrosis after injury. In this study, a poly (ε-caprolactone) (PCL) microfibrous scaffold infused with rat tail collagen type I was fabricated to obtain a 3D composite material. Physical and biological properties of PCL/collagen scaffold were evaluated, the effect of PCL/collagen scaffold on the proliferation and differentiation of limbal stromal stem cells (LSSCs) were detected in vitro, the differentiation of keratocytes as well as the expression and arrangement of extracellular matrix (ECM) influenced by PCL/collagen scaffold were investigated in vivo. RNA-sequencing on normal and injured corneas was carried out to find out the differential enriched pathways and gene expression. We discovered that the PCL/collagen scaffold simulated the stromal structure with properties that were most similar to the native cornea, the PCL/collagen scaffold exhibited good mechanical and biological properties. We also observed that the PCL/collagen scaffold reduced keratocyte differentiation. Injured corneas treated with PCL/collagen scaffold exhibited more regular collagen distribution and less fibroblasts and myofibroblasts distribution. By RNA-sequencing, we observed that in injured group, ECM-related pathway was enriched and several ECM-related genes were up-regulated. This study provides evidence that application of PCL/collagen scaffold could be a new therapeutic strategy for corneal injury.

Exosomes Derived from Bone Mesenchymal Stem Cells Alleviate Compression-Induced Nucleus Pulposus Cell Apoptosis by Inhibiting Oxidative Stress.

Oxidative stress is relevant in compression-induced nucleus pulposus (NP) cell apoptosis and intervertebral disc (IVD) degeneration. Exosomes derived from bone mesenchymal stem cells (BMSCs-Exos) are key secretory products of MSCs, with important roles in tissue regeneration. This research is aimed at studying the protective impact of BMSCs-Exos on NP cell apoptosis caused by compression and investigating the underlying mechanisms. Our results indicated that we isolated BMSCs successfully. Exosomes were isolated from the BMSCs and found to alleviate the inhibitory effect that compression has on proliferation and viability in NP cells, decreasing the toxic effects of compression-induced NP cells. AnnexinV/PI double staining and TUNEL assays indicated that the BMSCs-Exos reduced compression-induced apoptosis. In addition, our research found that BMSCs-Exos suppressed compression-mediated NP oxidative stress by detecting the ROS and malondialdehyde level. Furthermore, BMSCs-Exos increased the mitochondrial membrane potential and alleviated compression-induced mitochondrial damage. These results indicate that BMSCs-Exos alleviate compression-mediated NP apoptosis by suppressing oxidative stress, which may provide a promising cell-free therapy for treating IVD degeneration.

A General Crosslinker Strategy to Realize Intrinsic Frozen Resistance of Hydrogels.

Development and understanding of antifreezing materials are fundamentally and practically important for materials design and delivery. However, almost all of antifreezing materials are either organic/icephobic materials containing no water or hydrophilic hydrogels containing antifreezing additives. Here, a general crosslinking strategy to fabricate a family of EGINA-crosslinked double-network hydrogels with intrinsic, built-in antifreezing and mechanical properties, but without any antifreezing additives is proposed and demonstrated. The resultant hydrogels, despite large structural and compositional variations of hydrophilies, electrolytes, zwitterions, and macromolecules of polymer chains, achieved strong antifreezing and mechanical properties in different environments including solution state, gel state, and hydrogel/solid interfaces. Such general antifreezing property of EGINA-crosslinked hydrogels, regardless network compositions, is likely stemmed from their highly hydrophilic and tightly crosslinked DN structures for inducing strong water-network bindings to prevent ice crystal formation from free waters in hydrogel networks. EGINA-crosslinked hydrogels can also serve as a key component to be fabricated into smart windows with high optical transmittance and supercapacitors with excellent electrochemical stability at subzero temperatures. This work provides a simple, blueprint antifreezing design concept and a family of antifreezing hydrogels for the better understanding of the composite-structure-property relationship of antifreezing materials and the fundamentals of confined water in wet soft materials.