Aims:Mitochondrial redox homeostasis is closely linked to the ageing processes of tendons, whether in normal or pathological conditions. This study employed an innovative approach to examine the role of sirtuin 3 (SIRT3) in mitochondrial dysfunction in the aged murine supraspinatus tendon (ST). Methods:Pathological changes and collagen organization in tendons, along with variations in SIRT3 levels and oxidative stress, were initially assessed in mice of different ages. In vitro experiments were then performed to evaluate the effects of oxidative senescence on tendon cells, including cellular activity, phenotype, and collagen secretion. Finally, we explored the underlying mechanisms via which SIRT3 regulates mitochondrial redox homeostasis. Results:Histological and immunofluorescence analyses revealed a decline in SIRT3 levels within tenocytes as ageing progressed, accompanied by mitochondrial dysfunction and ageing-related phenotypes. The reduction in SIRT3 with age led to an increase in reactive oxygen species levels in tendon cells. However, enhancing SIRT3 expression in cells under oxidative stress was found to activate the SOD2 and Keap1/Nrf2/HO-1 signalling pathways, effectively reversing cellular senescence. Conclusion:SIRT3 plays a pivotal role in maintaining mitochondrial redox homeostasis in ST by regulating the mitochondrial antioxidant network to mitigate ageing and oxidative stress in tendon cells. Targeting SIRT3 in ST degeneration may offer a promising therapeutic approach.

Elucidating the identity of enthesis-resident progenitors is critical for advancing regenerative strategies, particularly in the context of the long-standing question of how is fibrocartilage formed at tendon enthesis (bone-tendon interface) under mechanical loading. To address the question of cellular origins of entheseal fibrocartilage, we first employed spatial transcriptional and single cell sequencing to identify a novel population of Tnn⁺ progenitor cells and delineate their lineage trajectories across developmental stages. Subsequently, we used a diphtheria toxin mediated ablation model targeting these Tnn⁺ progenitors and demonstrated their functional importance, as ablation resulted in hypoplastic phenotypes characterized by impaired fibrocartilage maturation. Furthermore, comparative single-cell profiling between unloaded entheses and normal entheses revealed that tendon unloading significantly diminished both the abundance and chondrogenic potential of Tnn⁺ progenitors. Collectively, these findings resolve fundamental questions regarding enthesis morphogenesis and provide mechanistic insights into how mechanical loading orchestrates this critical developmental process.

Bone–tendon interface (BTI) injuries pose a major clinical challenge because surgical repair often fails to restore the native enthesis and its structural and mechanical integrity. Although local repair mechanisms have been extensively studied, whether central neuroimmune circuits contribute to BTI healing remains unclear. Here, using a murine rotator cuff injury model, we provide evidence that BTI injury engages a sensory–central–sympathetic regulatory axis that contributes to impaired repair. BTI injury activated sensory afferent signaling and was associated with microglia-mediated neuroinflammation in the hypothalamic paraventricular nucleus (PVN), reduced PVN neuronal activity, and increased central adenosine-related signaling. Chemogenetic activation of PVN microglia suppressed PVN neuronal activity, enhanced sympathetic-associated changes, and impaired BTI healing, whereas microglial inhibition produced the opposite effects. Metabolomic, microdialysis, and pharmacological analyses identified extracellular adenosine as a microglia-associated signaling mediator, likely involving A1R-expressing PVN neurons. Downstream, increased sympathetic signaling at the healing interface was associated with elevated β2-adrenergic receptor (ADRB2) activity and reduced osteogenic and chondrogenic factor expression. Local ADRB2 blockade improved molecular, structural, and histological indices of BTI repair, supporting ADRB2 as a peripheral effector node of this neuroimmune–sympathetic pathway. Together, these findings suggest that central microglia–adenosine-related signaling contributes to BTI repair impairment through sympathetic ADRB2 activation. Targeting central neuroimmune signaling or local ADRB2 activity may provide potential strategies for improving BTI healing.

Objective: This study aimed to develop a dual-functional, cell-free therapeutic strategy combining sustained bioactive signaling with biomechanical support for rotator cuff repair by utilizing collagen-binding engineered exosomes derived from bone-cartilage-stromal progenitor cells (BCSPs). Methods: BCSPs (PDPN+CD146+) were isolated from human umbilical cord Wharton's jelly and genetically engineered to express collagen-binding peptide (CBP)-modified exosomes. These exosomes were encapsulated in decellularized cartilage extracellular matrix microspheres and incorporated into PLGA/quaternary ammonium chitosan/cartilage ECM electrospun scaffolds. The composite scaffold was evaluated for biocompatibility, sustained release kinetics, and stem cell chemotaxis/differentiation capacity in vitro. Therapeutic efficacy was assessed using a rat rotator cuff tear model. MicroRNA sequencing and mechanistic studies were conducted to identify regulatory pathways. Results: CBP-BCSP-Exos demonstrated significantly enhanced chondrogenic and osteogenic differentiation capacity compared to unmodified BCSP-Exos and conventional umbilical cord stem cell-derived exosomes. The collagen-binding modification enabled sustained release over 21 days. The optimized scaffold (10% w/v ECM) achieved optimal balance between mechanical strength, hydrophilicity, and cell adhesion. CBP-BCSP-Exos-M/ES significantly promoted bone marrow mesenchymal stem cell chemotaxis, proliferation, and bipotent differentiation. In vivo, CBP-BCSP-Exos-M/ES achieved superior biomechanical properties, enhanced subchondral bone regeneration, and organized fibrocartilage formation with type II collagen deposition. Mechanistically, miR-139-5p-enriched BCSP-Exos targeted GLI2 to relieve its inhibitory effects on chondrogenic and osteogenic differentiation. Conclusion: This study established a cell-free therapeutic strategy for rotator cuff repair. The CBP-BCSP-Exos-M/ES system, delivering miR-139-5p to inhibit GLI2 and promote gradient tissue regeneration, represents a promising translational approach for rotator cuff injury.

Spinal cord injury (SCI) induces metabolic and immune disruptions that impede tissue repair. However, the underlying mechanisms are poorly understood. In this study, we identified lactate accumulation as a critical driver of macrophage-mediated inflammation through histone H3K9 lactylation (H3K9la). Targeted metabolomics revealed elevated serum lactate levels in SCI patients, which were linked to increased glycolysis and lactate dehydrogenase activity. In mice, lactate accumulation after SCI was found to drive histone H3K9la in lesion-infiltrating macrophages and circulating monocytes. Integrated CUT&Tag and RNA-seq analysis revealed that thioredoxin-interacting protein (TXNIP) is a direct H3K9la target that activates the TXNIP-NLRP3 pathway, exacerbating inflammation and impairing mitochondrial function. In vitro, glycolytic inhibition reversed lactate-induced inflammation and mitochondrial dysfunction. In vivo, a hypoxia-responsive peptide inhibitor (H3K9la-pe) selectively reduced macrophage lactylation and inflammation, restored mitochondrial integrity, promoted axon regeneration, and significantly improved functional recovery in SCI mouse model. These findings elucidate a subacute metabolic-epigenetic-inflammatory axis in SCI and highlight that blocking macrophage H3K9la is a promising therapeutic strategy.

Age-related skeletal muscle aging can lead to sarcopenia and is closely associated with cellular senescence and mitochondrial dysfunction. Neonatal mammalian muscle exhibits a strong regenerative capacity, and neonatal muscle extracellular vesicles (NMEVs) show therapeutic potential against skeletal muscle aging. In this study, we isolated NMEVs for the first time and found that they significantly alleviated palmitic acid (PA)-induced senescence, mitochondrial dysfunction, and lipid accumulation in C2C12 cells. in vivo, we developed a bilayer microneedle (MN) system loaded with NMEVs (NMEVs@PLGA@Fucoidan-HA MN) and applied it to aged mice. The MN effectively enhanced mitochondrial function, reduced muscle aging and fibrosis, and decreased lipid deposition. Mechanistically, miR-542-3p enriched in NMEVs directly targeted and downregulated Asxl2-PPARγ, leading to reduced lipid accumulation. At the same time, it suppressed Eef1a1 to activate the AMPK pathway, thereby improving mitochondrial function and attenuating cellular senescence. Our findings demonstrate the protective role of NMEVs delivered via an innovative MN system against muscle aging, where miR-542-3p plays a central role by concurrently targeting Eef1a1 and Asxl2 to mitigate senescence and lipid dysregulation. This study reveals a novel molecular mechanism underlying the anti-aging potential of NMEVs and offers a promising therapeutic strategy for skeletal muscle aging.

Adult mammals with spinal cord injury (SCI) face permanent disability from failed regeneration and scarring, while neonatal mice achieve scarless repair. We show neonatal mouse circulating blood-derived small extracellular vesicles (NCE) rejuvenate adult spinal cord microvascular endothelial cells (SCMECs), restoring lipid metabolism, easing immune imbalance, and supporting neuroaxonal regrowth. Post-SCI myelin debris triggers IRS1-mediated PI3K-Akt-mTOR overactivation in SCMECs, causing harmful lipid droplet buildup, organelle dysfunction, and endothelial-to-mesenchymal transition (EndoMT). It also increases CXCL12 secretion from SCMECs, which recruits CXCR4+ macrophages. These macrophages release TNF-α and GDF15, promoting neuronal injury and EndoMT, and forming a destructive feedback loop. We create a “Microenvironment-Reprogramming Potent Hydrogel” - a high-adhesion GelNB hydrogel loaded with NCE - as an efficient delivery tool. NCE targetedly deliver miR-487b-3p to block IRS1 and CXCL12, breaking the vicious cycle. This remodels microvasculature, normalizes SCMEC lipid metabolism, reduces macrophage infiltration, promotes neuroregeneration, and achieves functional recovery. Our study uncovers an endothelium-immune crosstalk axis hindering SCI repair and highlights miR-487b-3p-rich sEVs as a promising therapy.

Spinal cord injury (SCI) is a severe and complex condition that can lead to significant physical impairments and affect the life quality of patients. Neural stem cells (NSCs) transplantation holds as a promising therapeutic approach for SCI. However, the challenging post-SCI microenvironment limits NSCs effectiveness. Our current research has found that transplanted NSCs, though with lower survival and differentiation, still aided in injury repair. Hypoxia was identified as a stressor inducing the release of extracellular vesicles (EVs) from NSCs through HIF-1α/RAB17 enhancing SCI repair. By extracting and modifying these EVs derived from hypoxia treated NSCs with CAQK/Angiopep2 peptides, we were able to accurately deliver them to the injury site, enhancing recovery without relying on cell survival or differentiation. This study delved into the reparative role and underlying mechanisms of transplanted NSCs in SCI, focusing on their non-cellular contributions and developed an innovative, targeted strategy for the transplantation of EVs derived from NSCs, offering a cell-free, precision therapeutic intervention for the treatment of SCI.

Existing stem cell‐based bone substitutes (SCBS) developed for repairing critical‐sized bone defects have several shortcomings, such as inconvenience for minimally‐invasive implantation, hard‐to‐completely fill defects, and insufficient osteogenesis of implanted stem cells. Mini‐bone organoids (mBOs), a new type of SCBS, show great potential to solve these shortcomings. Herein, after unveiling postnatal developmental dynamics of vertebra, vertebra in puberty shows superior osteogenesis and angiogenesis, thus selected as source tissue for decellularization, then fabricating into bone matrix microparticles (named pBM‐MPs) as cultivation matrix. The pBM‐MPs harbor osteo‐forming and biomimetic characteristics as well as functions of angiogenesis and anti‐senescence. Furthermore, a new cultivation pattern is developed for rapidly generating mBOs, namely cultivating a subpopulation of BMSCs showing strong osteogenic potential (named Osteo‐BMSCs) on the surface of pBM‐MPs undergoing FGF2‐stimulated early proliferation followed by BMP2‐induced late osteogenesis. In the presence of pBM‐MPs and Osteo‐BMSCs, the resulting mBOs exhibit similarities to native bone in terms of osteocyte phenotype, bony extracellular matrix and hold paracrine functions in angiogenesis and osteogenesis. Minimally‐invasive injection of the mBOs into rat femoral defect accelerates defect repair, indicating that this organoid serves as off‐the‐shelf substitute to completely fill defect even directly replace autologous bone, and paracrine units enhancing endogenous osteo‐formation.

Osteochondral defects (OCDs) pose a significant clinical challenge due to their limited self-repair capacity. The complex structure and distinct biological properties of articular cartilage and subchondral bone further complicate regeneration.In this study, we introduce a novel osteochondral regeneration strategy leveraging single-cell RNA sequencing (ScRNA-seq) to identify a unique population of skeletal stem cells (SSCs) derived from the infrapatellar fat pad (IFP). These SSCs exhibit high differentiation potential and robust chondrogenic capacity. Using flow cytometry, we isolated SSCs and extracted their exosomes (Exos), which were subsequently combined with hydrogels to develop a novel bioink. Employing 3D printing technology, we fabricated an innovative hydrogel scaffold designed to adapted to the defective areas enhance OCD repair.In a rat OCD model, the 3D-printed hydrogel scaffold loaded with SSC-derived Exos (SSC-Exos) demonstrated exceptional osteochondral regeneration, facilitating synchronous repair of both cartilage and subchondral bone. In vitro experiments revealed that SSC-Exos significantly enhanced the chondrogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Importantly, SSC-Exos derived from the IFP exhibited superior cartilage regeneration capabilities compared to Exos from adipose-derived mesenchymal stem cells (ADSC-Exos). High-throughput sequencing further elucidated the critical role of the microRNA-214-3p (miR-214-3p)/jagged canonical Notch ligand 2 (JAG2) axis in SSC-Exos-mediated cartilage regeneration. Collectively, the 3D-printed hydrogel scaffold loaded with SSC-Exos represents an innovative and effective strategy for OCD repair, with potential for clinical translation.

Following spinal cord injury (SCI), infiltrating macrophages excessively phagocytose myelin debris, subsequently transforming into foamy macrophages that significantly exacerbate secondary injury pathology. In this study, we developed cysteine-alanine-glutamine-lysine (CAQK) tetrapeptide-modified liposomes (Lip) encapsulating Rosuvastatin (designated as CAQK-Lip-R), specifically engineered for targeted delivery to SCI lesions, to systematically investigate both the therapeutic effects and molecular mechanisms underlying CAQK-Lip-R-mediated inhibition of foamy macrophage formation and promotion of functional recovery after spinal cord injury. The novel-designed CAQK-Lip-R demonstrated efficient accumulation at injury sites and exerted substantial neuroprotective effects, as evidenced by significantly promoted functional recovery in the injured spinal cord. Mechanistically, these therapeutic benefits were achieved through regulation of myelin lipid debris clearance and macrophage polarization conversion via enhanced autophagy initiation and progression, coupled with effective suppression of PI3K/Akt/mTOR signaling axis activity and concomitant augmentation of autophagic flux in macrophages. Our findings not only elucidate a previously unrecognized mechanism of CAQK-Lip-R action in preventing foamy macrophage formation within the injured spinal cord microenvironment, but also present an innovative therapeutic paradigm utilizing a lesion-homing nano-delivery system for SCI treatment.

Rationale: Spinal cord injury (SCI) is well-documented for its devastating impact on motor and sensory functions. However, its potential effects on cognitive function remain underexplored. This study aims to investigate the mechanisms of SCI-induced cognitive dysfunction, focusing on spinal cord-hippocampal communication mediated by extracellular vesicles (EVs). Methods: Cognitive function and hippocampal neurogenesis were assessed in mice subjected to either SCI or sham surgery. EVs were isolated from spinal cord tissues of SCI and sham groups and stereotactically injected into the hippocampus to evaluate their effects on cognition and neurogenesis. Cx3cr1-CreERT2 transgenic mice combined with AAV-CD63-EGFP injection were used to confirm the source of EVs. High-throughput sequencing was performed to identify differentially expressed miRNAs in EVs from SCI versus sham groups, with miR-152-3p selected for further analysis. RNA sequencing and dual-luciferase reporter assays were used to confirm whether miR-152-3p regulates cognition and neurogenesis via the WNT10b pathway. Finally, stereotactic injection of a WNT agonist was performed to assess its potential for restoring cognition and neurogenesis post-SCI. Results: This study demonstrates that SCI induces cognitive decline and impairs hippocampal neurogenesis in the dentate gyrus (DG) of mice. microglia-derived EVs were identified as critical mediators of communication between the spinal cord and hippocampus. Specifically, microglia-derived EVs were found to carry miR-152-3p, which inhibits WNT10b signaling, disrupts neurogenesis in the DG, and contributes to post-SCI cognitive deficits. Notably, activation of the WNT pathway in hippocampal neural stem cells (NSCs) after SCI promoted neurogenesis and significantly improved cognitive function in SCI mice. Conclusion: This study uncovers a novel microglia-derived EV-mediated communication axis between the spinal cord and hippocampus following SCI. It identifies the miR-152-3p/WNT10b axis as a key regulator of SCI-induced cognitive dysfunction and impaired neurogenesis. Activation of the WNT pathway was shown to restore neurogenesis and cognitive function, providing valuable insights into therapeutic strategies for SCI-associated cognitive impairments.

Introduction Spinal cord injury (SCI) stands as the primary cause of disability, still lacking a clear pathogenesis and effective treatment. The role of macrophages is particularly unclear in SCI, especially regarding cellular senescence. Additionally, the mechanisms driving macrophage senescence after SCI, the release of senescence-associated secretory phenotype (SASP) factors that affect the regenerative niche, and their contributions to SCI progression remain elusive. Objectives To investigate the role and underlying mechanism of Ubiquitously transcribed Tetratricopeptide repeat, X chromosome (UTX) in regulating macrophage senescence following SCI. Methods A contusive SCI model was constructed to explore the presence of senescent macrophages. After screening for UTX by a PCR array, conditioned knockout UTX mice (LysM-Cre; UTXflox/flox) was constructed to explore the effect of UTX on macrophage senescence to influence angiogenesis and neurological function. Furthermore, RNA-seq and ChIP-seq were carried out to screen the downstream target gene Matrix Metalloprotease-3 (MMP-3). At last, RNA-seq was performed to explore the effect of MMP-3 on endothelial cells in vitro. Results An elevated presence of lysine demethylase 6A (KDM6A/UTX), a special epigenetic regulatory modifier, was observed in macrophage senescence after SCI. Conditional deletion of UTX not only prevented macrophage senescence, but also enhanced the formation of a regenerative niche that protected endothelial cells from senescence and improved their proliferation. Mechanistically, UTX epigenetically regulated MMP-3 transcription through demethylating histone H3 lysine di/trimethylation (H3K27me2/3) at its promoter region. This led to senescent macrophages releasing MMP-3, a key SASP factor that disrupts the local microenvironment and impairs spinal cord repair post-injury. Notably, MMP-3 could act as a pro-senescent agent by senescent macrophages to propagate cellular senescence in endothelial cells (ECs), exacerbating cellular senescence in the injured region. Conclusions Our findings elucidate the KDM6A/MMP-3 epigenetic regulatory axis, which governs macrophage senescence and creates an inhibitory microenvironment for regeneration after SCI. Targeting this pathway promotes angiogenesis and facilitates neural repair, highlighting its potential as a therapeutic target for improving functional recovery after SCI.

Background:Rotator cuff injury (RCI) often leads to chronic pain and anxiety, yet the underlying neural mechanisms remain unclear. This study explored central mechanisms linking RCI to these symptoms and assessed treadmill exercise (TE) as a therapeutic intervention in mice. Methods:Male C57BL/6 mice underwent RCI surgery and were randomized into Sham, RCI, or TE groups (TE initiated on postoperative day 7). Mechanical hypersensitivity and anxiety-like behaviors were evaluated via von Frey, elevated plus maze, and open field tests. Synaptic plasticity proteins and structures in the paraventricular nucleus (PVN) were analyzed using immunofluorescence, Western blotting, electron microscopy, and Golgi staining. The brain-derived neurotrophic factor-tropomyosin receptor kinase B (BDNF-TrkB) pathway's role was tested using the TrkB inhibitor ANA-12. Results:RCI elicited notable alterations in synaptic structure within the PVN, characterized by decreased synaptophysin expression, increased growth-associated protein 43 expression, and synaptic microstructural abnormalities. These synaptic modifications were correlated with the manifestation of hyperalgesia and anxiety-like behaviors in murine models. TE reversed these synaptic changes and improved pain and anxiety symptoms. Mechanistically, TE activated the BDNF-TrkB signaling pathway in the PVN, which was essential for its therapeutic effects. Pharmacological blockade of the TrkB receptor using ANA-12 attenuated the therapeutic benefits of TE, confirming the critical role of BDNF-TrkB signaling pathway. Conclusion:TE mitigates RCI-related pain and anxiety by restoring PVN synaptic plasticity via BDNF-TrkB signaling, underscoring exercise's therapeutic potential. The translational potential of this article:The study reveals new insights into the central neural mechanisms of pain and anxiety after RCI, highlighting synaptic plasticity changes in the PVN. It clarifies the link between peripheral injury and central nervous system alterations, guiding clinicians toward more targeted and effective treatments.

Mitochondria are crucial in sustaining and orchestrating cellular functions. Capitalizing on this, we explored mitochondrial transplantation as an innovative therapeutic strategy for acute spinal cord injury (SCI). In our study, we developed an engineered mitochondrial compound tailored to target macrophages within the SCI region. Sourced from IL-10-induced Mertkhi bone marrow-derived macrophages, we conjugated a peptide sequence, cations-cysteine-alanine-glutamine-lysine (CAQK), with the mitochondria, optimizing its targeting affinity for the injury site. Our data demonstrated that these compounds significantly enhanced macrophage phagocytosis of myelin debris, curtailed lipid buildup, ameliorated mitochondrial dysfunction, and attenuated pro-inflammatory profiles in macrophages, both in vitro and in vivo. The intravenously delivered mitochondrial compounds targeted the SCI epicenter, with macrophages being the primary recipients. Critically, they promoted tissue regeneration and bolstered functional recovery in SCI mice. This study heralds a transformative approach to mitochondrial transplantation in SCI, spotlighting the modulation of macrophage activity, phagocytosis, and phenotype.

Rationale: Spinal cord injury (SCI) results in neural tissue damage. However, the limited regenerative capacity of adult mammals' axons upon SCI leads to persistent neurological dysfunction. Thus, exploring the pathways that can enhance axon regeneration in injured spinal cord is of great significance. Methods: Through the utilization of single-cell RNA sequencing in this research, a distinct subpopulation of bone marrow mesenchymal stem cells (BMSCs) that exhibits the capacity to facilitate axon regeneration has been discovered. Subsequently, the CD271+CD56+ BMSCs subpopulation was isolated using flow cytometry, and the exosomes derived from this subpopulation (CD271+CD56+ BMSC-Exos) were extracted and incorporated into a hydrogel to create a sustained release system. The aim was to investigate the therapeutic effects of CD271+CD56+ BMSC-Exos and elucidate the underlying mechanisms involved in promoting axon regeneration and neural function recovery. Results: The findings indicate that CD271+CD56+ BMSC-Exos share similar physical and chemical properties with conventional exosomes. Importantly, in an SCI model, in situ implantation of CD271+CD56+ BMSC-Exos hydrogel resulted in increased expression of NF and synaptophysin, markers associated with axon regeneration and synapse formation, respectively. This intervention also contributed to improved neural function recovery. In vitro experiments demonstrated that CD271+CD56+ BMSC-Exos treatment significantly enhanced axon extension distance and increased the number of branches in dorsal root ganglion axons. Moreover, further investigation into the molecular mechanisms underlying CD271+CD56+ BMSC-Exos-mediated axon regeneration revealed the crucial involvement of the miR-431-3p/RGMA axis. Conclusion: In summary, the implantation of CD271+CD56+ BMSC-Exos hydrogel presents a promising and effective therapeutic approach for SCI.

Background: Bone morphogenetic protein 2 (BMP2) is an appealing osteogenic and chondrogenic growth factor for promoting tendon-bone healing. Recently, it has been reported that soluble vascular endothelial growth factor (VEGF) receptor 1 (sVEGFR1) (a VEGF receptor antagonist) could enhance BMP2-induced bone repair and cartilage regeneration; thus, their combined application may represent a promising treatment to improve tendon-bone healing. Moreover, BMP2 could stimulate skeletal stem cell (SSC) expansion and formation, which is responsible for wounded tendon-bone interface repair. However, whether the codelivery of BMP2 and sVEGFR1 increases tendon enthesis injury-activated SSCs better than does BMP2 alone needs further research.Purpose: To study the effect of BMP2 combined with sVEGFR1 on tendon-bone healing and injury-activated SSC lineage.Study Design: Controlled laboratory study.Methods: A total of 128 C57BL/6 mice that underwent unilateral supraspinatus tendon detachment and repair were randomly assigned to 4 groups: (1) untreated control group; (2) hydrogel group, which received a local injection of the blank hydrogel at the injured site; (3) BMP2 group, which received an injection of hydrogel with BMP2; and (4) BMP2 with sVEGFR1 group, which received an injection of hydrogel with BMP2 and sVEGFR1. Histology, micro-computed tomography, and biomechanical tests were conducted to evaluate tendon-bone healing at 4 and 8 weeks after surgery. In addition, flow cytometry was performed to detect the proportion of SSCs and their downstream differentiated subtypes, including bone, cartilage, and stromal progenitors; osteoprogenitors; and pro-chondrogenic progenitors within supraspinatus tendon enthesis at 1 week postoperatively.Results: The repaired interface in BMP2 with sVEGFR1 group showed a significantly improved collagen fiber continuity, increased fibrocartilage, greater newly formed bone, and elevated mechanical properties compared with the other 3 groups. There were more SSCs; bone, cartilage, and stromal progenitors; osteoprogenitors; and pro-chondrogenic progenitors in the BMP2 with sVEGFR1 group than that in the other groups.Conclusion: Our study suggests that the combined delivery of BMP2 and sVEGFR1 could promote tendon-bone healing and stimulate the expansion of SSCs and their downstream progeny within the injured tendon-bone interface.Clinical Relevance: Combining BMP2 with sVEGFR1 may be a good clinical treatment for wounded tendon enthesis healing.

Hemorrhage and immune cell infiltration are the main pathological features of spinal cord injury (SCI). Excessive iron deposition is caused by leaking hemosiderin which may over-activate ferroptosis pathways, resulting in lipid peroxidation and mitochondrial dysfunction in cells. Inhibiting ferroptosis after SCI has been shown to aid functional recovery. However, the essential genes involved in cellular ferroptosis following SCI are still unknown. Here we show that Ctsb is a statistical significance gene by collecting multiple transcriptomic profiles and identifying differentially expressed ferroptosis-related genes, which are abundantly expressed in myeloid cells after SCI and widely distributed at the epicenter of the injury. The expression score of ferroptosis, calculated by ferroptosis driver/suppressor genes, was high in macrophages. Furthermore, we discovered that inhibiting cathepsin B (CTSB), specifically with a small-molecule drug, CA-074-methyl ester (CA-074-me), reduced lipid peroxidation and mitochondrial dysfunction in macrophages. We also found that alternatively activated M2-polarized macrophages are more susceptible to hemin-induced ferroptosis. Consequently, CA-074-me could reduce ferroptosis, induce M2 macrophage polarization, and promote the neurological function recovery of mice after SCI. Our study comprehensively analyzed the ferroptosis after SCI from the perspective of multiple transcriptomes and provided a novel molecular target for SCI treatment.

The treatment of diabetic wounds possessed significant challenges in clinical practice, which was accompanied with continuous infection, inflammation, and limited angiogenesis. Current wound dressings used for diabetic wound healing struggle to address these issues simultaneously. Therefore, Ga3+ was added to the chitosan/silk solution to confer potent antibacterial properties. Subsequently, umbilical cord mesenchymal stem cell exosomes (UCSC-Exo) were integrated into the gallium/chitosan/silk solution to enhance its angiogenesis-inducing activity. The mixture was lyophilized to prepare gallium/chitosan/silk/exosome sponge scaffolds (Ga/CSSF-Exo sponge scaffolds). The experiments of In vitro and in vivo demonstrated that Ga/CSSF-Exo sponge scaffolds exhibited sustained release of Ga3+ and bioactive exosomes, which effectively exerted continuous antibacterial effects and promoted angiogenesis. In diabetic rat wound models, Ga/CSSF-Exo sponge scaffolds facilitated angiogenesis, suppressed bacterial growth and inflammation, as well as promoted collagen deposition and re-epithelialization of wounds. Collectively, our findings suggested that Ga/CSSF-Exo held excellent potential for diabetic wound healing.

Spinal cord injury typically causes corticospinal tract disruption. Although the disrupted corticospinal tract can self-regenerate to a certain degree, the underlying mechanism of this process is still unclear. N 6 -methyladenosine (m 6 A) modifications are the most common form of epigenetic regulation at the RNA level and play an essential role in biological processes. However, whether m 6 A modifications participate in corticospinal tract regeneration after spinal cord injury remains unknown. We found that expression of methyltransferase 14 protein (METTL14) in the locomotor cortex was high after spinal cord injury and accompanied by elevated m 6 A levels. Knockdown of Mettl14 in the locomotor cortex was not favorable for corticospinal tract regeneration and neurological recovery after spinal cord injury. Through bioinformatics analysis and methylated RNA immunoprecipitation-quantitative polymerase chain reaction, we found that METTL14 regulated Trib2 expression in an m 6 A-regulated manner, thereby activating the mitogen-activated protein kinase pathway and promoting corticospinal tract regeneration. Finally, we administered syringin, a stabilizer of METTL14, using molecular docking. Results confirmed that syringin can promote corticospinal tract regeneration and facilitate neurological recovery by stabilizing METTL14. Findings from this study reveal that m 6 A modification is involved in the regulation of corticospinal tract regeneration after spinal cord injury.