Enhancing m6A modification in the motor cortex facilitates corticospinal tract remodeling after spinal cord injury.

JOURNAL/nrgr/04.03/01300535-202506000-00026/figure1/v/2024-08-05T133530Z/r/image-tiff 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. N6-methyladenosine (m6A) modifications are the most common form of epigenetic regulation at the RNA level and play an essential role in biological processes. However, whether m6A 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 m6A 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 m6A-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 m6A modification is involved in the regulation of corticospinal tract regeneration after spinal cord injury.

Polycyclic aromatic hydrocarbons in fish from four lakes in central and eastern China: Bioaccumulation, pollution characteristics, sources, and health risk assessment.

Polycyclic aromatic hydrocarbons (PAHs) are highly concerning environmental pollutants due to their toxicity, persistence, and bioaccumulation. In this paper, concentrations and compositions of 16 United States Environmental Protection Agency (USEPA) priority control PAHs in the fish collected from four lakes in central and eastern China were analyzed. 18 species of fish were collected from four typical lakes, namely Taihu Lake, Danjiangkou Reservoir, Yuncheng Salt Lake, and Nansi Lake. Quantitative analysis of PAHs were carried out with gas chromatograph/mass spectrometer, and 13 out of 16 PAHs were identified, with the main components being pyrene, chrysene, naphthalene, and benzo(b)fluoranthene. The accumulation of PAHs in fish from Taihu Lake, Danjiangkou Reservoir, Yuncheng Salt Lake, and Nansi Lake was 28.75-47.27, 26.60-31.93, 33.56-39.30, and 27.22-43.01 ng·g-1, respectively. The toxic equivalents of high-cyclic PAHs in fish of the four lakes were significantly higher than those of low-cyclic and middle-cyclic PAHs (P < 0.05). In Taihu Lake, Danjiangkou Reservoir, and Nansi Lake, the toxicity equivalents were predominantly contributed by benzo[a] pyrene (BaP), while in Yuncheng Salt Lake, dibenzo(a,h) anthracene (DahA) was the main contributor. The residents in central and eastern China exposed to PAHs had a negligible non-cancer risk (non-carcinogenic risk values <1) and a potential low cancer risk. It was noteworthy that the Pleuronichthys cornutus and Lateolabrax japonicus from Yuncheng Salt Lake could pose carcinogenic risks (>10-4) to humans, with benzo[b]fluoranthene (BbF) having the highest risk contribution rate. Source analysis indicated that the main source of PAHs in fish was combustion sources. BaP, DahA, and BbF could become potential pollutants of concern in the field of ecotoxicology. The results of this study on PAHs bioaccumulation, pollution characteristics, sources and health risks in fish from four lakes would provide a scientific basis for local governments to formulate targeted environmental management policies, pollution control measures, and public health strategies.

Bone controls browning of white adipose tissue and protects from diet-induced obesity through Schnurri-3-regulated SLIT2 secretion.

The skeleton has been suggested to function as an endocrine organ controlling whole organism energy balance, however the mediators of this effect and their molecular links remain unclear. Here, utilizing Schnurri-3-/- (Shn3-/-) mice with augmented osteoblast activity, we show Shn3-/-mice display resistance against diet-induced obesity and enhanced white adipose tissue (WAT) browning. Conditional deletion of Shn3 in osteoblasts but not adipocytes recapitulates lean phenotype of Shn3-/-mice, indicating this phenotype is driven by skeleton. We further demonstrate osteoblasts lacking Shn3 can secrete cytokines to promote WAT browning. Among them, we identify a C-terminal fragment of SLIT2 (SLIT2-C), primarily secreted by osteoblasts, as a Shn3-regulated osteokine that mediates WAT browning. Lastly, AAV-mediated Shn3 silencing phenocopies the lean phenotype and augmented glucose metabolism. Altogether, our findings establish a novel bone-fat signaling axis via SHN3 regulated SLIT2-C production in osteoblasts, offering a potential therapeutic target to address both osteoporosis and metabolic syndrome.

Comparative effect of skeletal stem cells versus bone marrow mesenchymal stem cells on rotator cuff tendon-bone healing.

Background: Bone marrow mesenchymal stem cells (BMSCs) have immense potential in applications for the enhancement of tendon-bone (T-B) healing. Recently, it has been well-reported that skeletal stem cells (SSCs) could induce bone and cartilage regeneration. Therefore, SSCs represent a promising choice for cell-based therapies to improve T-B healing. In this study, we aimed to compare the therapeutic potential of SSCs and BMSCs for tendon-bone healing. Methods: SSCs and BMSCs were isolated by flow cytometry, and their proliferation ability was measured by CCK-8 assay. The osteogenic, chondrogenic, and adipogenic gene expression in cells was detected by quantitative real-time polymerase chain reaction (qRT-PCR). C57BL/6 mice underwent unilateral supraspinatus tendon detachment and repair, and the mice were then randomly allocated to 4 groups: control group (tendon-bone interface without any treatment), hydrogel group (administration of blank hydrogel into the tendon-bone interface), hydrogel + BMSCs group (administration of hydrogel with BMSCs into the tendon-bone interface), and hydrogel + SSCs group (administration of hydrogel with SSCs into the tendon-bone interface). Histological staining, Micro-computed tomography (Micro-CT) scanning, biomechanical testing, and qRT-PCR were performed to assay T-B healing at 4 and 8 weeks after surgery. Results: SSCs showed more cell proportion, exhibited stronger multiplication capacity, and expressed higher osteogenic and chondrogenic markers and lower adipogenic markers than BMSCs. In vivo assay, the SSCs group showed a better-maturated interface which was characterized by richer chondrocytes and more proteoglycan deposition, as well as more newly formed bone at the healing site and increased mechanical properties when compared to other there groups. qRT-PCR analysis revealed that the healing interface in the SSCs group expressed more transcription factors essential for osteogenesis and chondrogenesis than the interfaces in the other groups. Conclusions: Overall, the results demonstrated the superior therapeutic potential of SSCs over BMSCs in tendon-bone healing. The translational potential of this article: This current study provides valuable insights that SSCs may be a more effective cell therapy for enhancing T-B healing compared to BMSCs.

Functional nanotransducer-mediated wireless neural modulation techniques.

Functional nanomaterials have emerged as versatile nanotransducers for wireless neural modulation because of their minimal invasion and high spatiotemporal resolution. The nanotransducers can convert external excitation sources (e.g. NIR light, x-rays, and magnetic fields) to visible light (or local heat) to activate optogenetic opsins and thermosensitive ion channels for neuromodulation. The present review provides insights into the fundamentals of the mostly used functional nanomaterials in wireless neuromodulation including upconversion nanoparticles, nanoscintillators, and magnetic nanoparticles. We further discussed the recent developments in design strategies of functional nanomaterials with enhanced energy conversion performance that have greatly expanded the field of neuromodulation. We summarized the applications of functional nanomaterials-mediated wireless neuromodulation techniques, including exciting/silencing neurons, modulating brain activity, controlling motor behaviors, and regulating peripheral organ function in mice. Finally, we discussed some key considerations in functional nanotransducer-mediated wireless neuromodulation along with the current challenges and future directions.

Complete mitochondrial genome of the giant triton snail Charonia tritonis (Tonnoidea: Charoniidae).

The giant triton snail, Charonia tritonis (Linnaeus, 1758), crucial for coral reef ecosystems as a primary predator of the crown-of-thorns sea star, is experiencing a significant decline due to overfishing for its ornamental shell, underscoring the urgent need for conservation and deeper understanding of its role within marine biodiversity. This study presents the first complete mitogenome sequence of C. tritonis. Spanning 15,346 bp, the C. tritonis mitogenome comprises 13 protein-coding genes (PCGs), 22 tRNA genes, and two rRNA genes. Phylogenetic analysis of 88 Littorinimorpha mitogenomes confirms C. tritonis and C. lampas are grouped together within the family Charoniidae as a sister group to the remaining Tonnoidea families. This research not only enhances the taxonomic classification and conservation efforts for marine gastropods but also serves as a vital reference for future evolutionary and genetic studies within the Caenogastropoda.

[Retracted] MicroRNA­336 directly targets Sox­2 in osteosarcoma to inhibit tumorigenesis.

Following the publication of this paper, it was drawn to the Editor's attention by a concerned reader that certain of the Transwell cell migration and invasion assay data in Fig. 3C and D, and the tumour images shown in Fig. 4A were strikingly similar to data appearing in different form in other articles written by different authors at different research institutes, which had already been published. In addition, certain of the data panels shown in Fig. 3C were overlapping, such that the data from the same original source had been selected to represent the results from allegedly differently performed experiments. Owing to the fact that the contentious data in the above article had already been published prior to its submission to Molecular Medicine Reports, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a reply. The Editor apologizes to the readership for any inconvenience caused. [Molecular Medicine Reports 15: 4217­4224, 2017; DOI: 10.3892/mmr.2017.6493].

Dual-functional gallium/chitosan/silk/umbilical cord mesenchymal stem cell exosome sponge scaffold for diabetic wound by angiogenesis and antibacteria.

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.

A Multifunctional Additive Based on the Cation-Anion Synergistic Effect for Highly Stable Zinc Metal Anodes.

The Zn dendrite and hydrogen evolution reaction have been a "stubborn illness" for the life span of zinc anodes, which significantly hinders the development of aqueous zinc batteries (AZBs). Herein, considering the ingenious molecular structure, a multifunctional additive based on the synergistic regulation of cations and anions at the interface is designed to promote a dendrite-free and stable Zn anode. Theoretical calculations and characterization results verified that the electrostatic shield effect of the cation, the solvation sheath structure, and the bilayer structural solid electrolyte film (SEI) jointly account for the uniform Zn deposition and side reaction suppression. Ultimately, a remarkably high average Coulombic efficiency (CE) of 99.4% is achieved in the Zn||Cu cell for 300 cycles, and a steady charge/discharge cycling over 3000 and 300 h at 1.0 mA cm-2/1.0 mAh cm-2 and 10 mA cm-2/10 mAh cm-2 is obtained in the Zn||Zn cell. Furthermore, the assembled full battery demonstrates a prolonged cycle life of 2000 cycles.

Engineering a functional ACL reconstruction graft containing a triphasic enthesis-like structure in bone tunnel for the enhancement of graft-to-bone integration.

Background: Anterior cruciate ligament (ACL) rupture is a common sports injury, which causes knee instability and abnormal joint kinematics. The current ACL graft was single-phasic, and not convenient for the formation of enthesis-like tissue in the bone tunnel, resulting in poor integration of graft-to-bone. Methods: A band-shaped acellular tendon (BAT) was prepared as the core component of the ACL reconstruction graft at first, while sleeve-shaped acellular cartilage (SAC) or sleeve-shaped acellular bone (SAB) was fabricated using a vacuum aspiration system (VAS)-based decellularization protocol. The biocompatibility of the three acellular matrixes was evaluated. Furthermore, a collagen-binding peptide (CBP) derived from the A3 domain of von Willebrand factor was respectively fused into the N-terminal of GDF7, TGFß3, or BMP2 to synthesize three recombinant growth factors capable of binding collagen (named C-GDF7, C-TGFß3, or C-BMP2), which were respectively tethered to the BAT, SAC or SAB for improving their inducibilities in stem cell differentiation. An in-vitro experiment was performed to evaluate theirs osteogenic, chondrogenic, and tenogenic inducibilities. Then, C-TGFß3-tethering SAC (C-TGFß3@SAC) and C-BMP2-tethering SAB (C-BMP2@SAB) were sequentially surrounded at the bone tunnel part of C-GDF7-tethering BAT (C-GDF7@BAT), thus a sleeve-shaped acellular graft with a triphasic enthesis-like structure in bone tunnel part (named tissue-engineered graft, TE graft) was engineered. Lastly, a canine ACL reconstruction model was used to evaluate the in-vivo performance of this TE graft in enhancing graft-to-bone integration. Results: The BAT, SAC, and SAB well preserved the structure and components of native tendon, cartilage, and bone, showing good biocompatibility. C-GDF7, C-TGFß3, or C-BMP2 showed a stronger binding ability to BAT, SAC, and SAB. The C-GDF7@BAT, C-TGFß3@SAC, or C-BMP2@SAB was a controlled delivery system for the scaffold-specific release of GDF7, TGFß3, and BMP2, thus showing superior tenogenic, chondrogenic, or osteogenic inducibility, respectively. Using a canine ACL reconstruction model, abundant newly-formed bone and connective collagen fibers could be observed at the integration site between TE graft and bone tunnel at postoperative 16 weeks. Meanwhile, the failure load of the reconstructed ACL by TE graft was significantly higher than that of the autograft. Conclusion: The TE graft could be used to reconstruct ruptured ACL and augment graft-to-bone integration, thus demonstrating high potential for clinical translation in ACL reconstruction. Translational potential of this article: The findings of the study indicated that the TE graft could be a novel graft for ACL reconstruction with the ability to augment graft-to-bone integration, which may provide a foundation for future clinical application.

Intranasal delivery of small extracellular vesicles from specific subpopulation of mesenchymal stem cells mitigates traumatic spinal cord injury.

Vascular injury following spinal cord injury (SCI) can significantly exacerbate secondary SCI and result in neurological dysfunction. Strategies targeting angiogenesis have demonstrated potential in enhancing functional recovery post-SCI. In the context of angiogenesis, the CD146+ and CD271+ subpopulations of mesenchymal stem cells (MSCs) have been recognized for their angiogenic capabilities in tissue repair. Small extracellular vesicles (sEVs) derived from MSCs are nanoscale vesicles containing rich bioactive components that play a crucial role in tissue regeneration. However, the precise role of sEVs derived from CD146+CD271+ UCMSCs (CD146+CD271+ UCMSC-sEVs) in SCI remain unclear. In this study, CD146+CD271+ UCMSC-sEVs were non-invasively administered via intranasal delivery, demonstrating a significant capacity to stimulate angiogenesis and improve functional recovery in mice following SCI. Furthermore, in vitro assessments revealed the effective enhancement of migration and tube formation capabilities of the murine brain microvascular endothelial cell line (bEnd.3) by CD146+CD271+UCMSC-sEVs. MicroRNA array analysis confirmed significant enrichment of multiple microRNAs within CD146+CD271+ UCMSC-sEVs. Subsequent in vivo and in vitro experiments demonstrated that CD146+CD271+ UCMSC-sEVs promote enhanced angiogenesis and improved functional recovery mediated by miR-27a-3p. Further mechanistic studies revealed that miR-27a-3p sourced from CD146+CD271+ UCMSC-sEVs enhances migration and tube formation of bEnd.3 cells in vitro by suppressing the expression of Delta Like Canonical Notch Ligand 4 (DLL4), thereby promoting angiogenesis in vivo. Collectively, our results demonstrate that a crucial role of CD146+CD271+ UCMSC-sEVs in inhibiting DLL4 through the transfer of miR-27a-3p, which leads to the promotion of angiogenesis and improved functional recovery after SCI.

[Distribution Characteristics, Ecological Risk Assessment, and Source Tracing of Heavy Metals in the Sediments of Typical Lakes in the Middle Reaches of the Yangtze River].

In this study, surface sediment samples were collected from Dongting Lake, Honghu Lake, and Chihu Lake, and the concentrations of 10 heavy metals were measured. Then, the potential risk of heavy metal accumulation was evaluated using the cumulative pollution index (Igeo), the enrichment factor (EF), and the potential ecological risk index (RI), and the sources were traced using correlation analysis (Pearson) and principal component analysis (PCA). The results showed that the pollution and potential ecological risk of Cd were the most serious. The mean values of Cd in East Dongting Lake, Honghu Lake, and Chihu Lake were 2.85, 1.59, and 3.57 mg·kg-1, respectively. The concentrations of Cd were 25.87, 11.36, and 37.58 times higher than the soil background values of the corresponding provinces, which exceeded the risk screening value (0.6 mg·kg-1). Particularly, the Cd concentration of Chihu Lake exceeded the risk control value (3.0 mg·kg-1). Besides Cd, the concentration of As in Honghu Lake was also of concern. At the same time, the Cu, As, Zn, and Pb in Chihu Lake should not be neglected. The potential ecological risks of the three lakes were ranked as follows:Chihu Lake (RI=1 127)>East Dongting Lake (RI=831)>Honghu Lake (RI=421). The primary sources of heavy metals were industrial mining, agricultural production, and aquaculture, and some heavy metals (Mn and Cu) were from natural sources. This study was of great significance for the prevention and control of heavy metals in the sediments of typical lakes in the middle reaches of the Yangtze River.

Kdm6a-CNN1 axis orchestrates epigenetic control of trauma-induced spinal cord microvascular endothelial cell senescence to balance neuroinflammation for improved neurological repair.

Cellular senescence assumes pivotal roles in various diseases through the secretion of proinflammatory factors. Despite extensive investigations into vascular senescence associated with aging and degenerative diseases, the molecular mechanisms governing microvascular endothelial cell senescence induced by traumatic stress, particularly its involvement in senescence-induced inflammation, remain insufficiently elucidated. In this study, we present a comprehensive demonstration and characterization of microvascular endothelial cell senescence induced by spinal cord injury (SCI). Lysine demethylase 6A (Kdm6a), commonly known as UTX, emerges as a crucial regulator of cell senescence in injured spinal cord microvascular endothelial cells (SCMECs). Upregulation of UTX induces senescence in SCMECs, leading to an amplified release of proinflammatory factors, specifically the senescence-associated secretory phenotype (SASP) components, thereby modulating the inflammatory microenvironment. Conversely, the deletion of UTX in endothelial cells shields SCMECs against senescence, mitigates the release of proinflammatory SASP factors, and promotes neurological functional recovery after SCI. UTX forms an epigenetic regulatory axis by binding to calponin 1 (CNN1), orchestrating trauma-induced SCMECs senescence and SASP secretion, thereby influencing neuroinflammation and neurological functional repair. Furthermore, local delivery of a senolytic drug reduces senescent SCMECs and suppresses proinflammatory SASP secretion, reinstating a local regenerative microenvironment and enhancing functional repair after SCI. In conclusion, targeting the UTX-CNN1 epigenetic axis to prevent trauma-induced SCMECs senescence holds the potential to inhibit SASP secretion, alleviate neuroinflammation, and provide a novel treatment strategy for SCI repair.

Impacts of sulfamethoxazole stress on vegetable growth and rhizosphere bacteria and the corresponding mitigation mechanism.

Antibiotics are an important pharmaceutical class excessively used by humans. Its presence in the soil can impact plant growth and induce antibiotic resistance. This research studies the effect of sulfamethoxazole (SMX) on plant growth, rhizosphere bacteria composition, and resistance genes. Two sets of vegetables (basil, cilantro, and spinach) were treated separately with water and SMX solution. The plant growth data and soil samples were collected and analyzed. The results revealed that SMX increased spinach leaf length (34.0%) while having no significant impacts on basil and cilantro. On the other hand, SMX improved the bacterial diversity in all samples. The shifts in the abundance of plant growth-promoting bacteria could indirectly affect vegetable stem and leaf length. SMX also significantly increased the abundance of resistance genes Sul1 and Sul2. A further study into the correlation between bacteria highlights the importance of Shingomonas and Alfipia for inhibiting the spread of key resistance gene hosts, namely, Pseudomonas, Stenotrophomonas, and Agrobacterium. This research provides insight into SMX's impact on vegetable growth and microbial diversity. It also points out important microbial interactions that could potentially be utilized to mitigate ARG proliferation.

A Combined Treatment of BMP2 and Soluble VEGFR1 for the Enhancement of Tendon-Bone Healing by Regulating Injury-Activated Skeletal Stem Cell Lineage.

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.

Functionalization of the Octahydro-Binaphthol Skeleton: A Universal Strategy for Directly Constructing D-A Type Axially Chiral Biphenyl Luminescent Molecules.

D-A type axially chiral biphenyl luminescent molecules are directly constructed through ingenious functionalization of the octahydro-binaphthol skeleton without optical resolution. The circularly polarized organic light-emitting diodes based on them display remarkable circularly polarized electroluminescence emission, a high luminance of >10 000 cd m-2, a maximum external quantum efficiency of 6.6%, and an extremely low-efficiency roll-off. This work provides a universal strategy for developing efficient and diverse axially chiral biphenyl emitters.

Extracellular vesicles from UTX-knockout endothelial cells boost neural stem cell differentiation in spinal cord injury.

BACKGROUND: Vascular endothelial cells are pivotal in the pathophysiological progression following spinal cord injury (SCI). The UTX (Ubiquitously Transcribed Tetratripeptide Repeat on Chromosome X) serves as a significant regulator of endothelial cell phenotype. The manipulation of endogenous neural stem cells (NSCs) offers a compelling strategy for the amelioration of SCI. METHODS: Two mouse models were used to investigate SCI: NSCs lineage-traced mice and mice with conditional UTX knockout (UTX KO) in endothelial cells. To study the effects of UTX KO on neural differentiation, we harvested extracellular vesicles (EVs) from both UTX KO spinal cord microvascular endothelial cells (SCMECs) and negative control SCMECs. These EVs were then employed to modulate the differentiation trajectory of endogenous NSCs in the SCI model. RESULTS: In our NSCs lineage-traced mice model of SCI, a marked decrease in neurogenesis was observed post-injury. Notably, NSCs in UTX KO SCMECs mice showed enhanced neuronal differentiation compared to controls. RNA sequencing and western blot analyses revealed an upregulation of L1 cell adhesion molecule (L1CAM), a gene associated with neurogenesis, in UTX KO SCMECs and their secreted EVs. This aligns with the observed promotion of neurogenesis in UTX KO conditions. In vivo administration of L1CAM-rich EVs from UTX KO SCMECs (KO EVs) to the mice significantly enhanced neural differentiation. Similarly, in vitro exposure of NSCs to KO EVs resulted in increased activation of the Akt signaling pathway, further promoting neural differentiation. Conversely, inhibiting Akt phosphorylation or knocking down L1CAM negated the beneficial effects of KO EVs on NSC neuronal differentiation. CONCLUSIONS: In conclusion, our findings substantiate that EVs derived from UTX KO SCMECs can act as facilitators of neural differentiation following SCI. This study not only elucidates a novel mechanism but also opens new horizons for therapeutic interventions in the treatment of SCI. Video Abstract.

Exosomes derived from CD271+CD56+ bone marrow mesenchymal stem cell subpopoulation identified by single-cell RNA sequencing promote axon regeneration after spinal cord injury.

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.

Optimized Allogenic Decellularized Meniscal Scaffold Modified by Collagen Affinity Stromal Cell-Derived Factor SDF1α for Meniscal Regeneration: A 6- and 12-Week Animal Study in a Rabbit Model.

BACKGROUND: Total meniscectomy for treating massive meniscal tears may lead to joint instability, cartilage degeneration, and even progressive osteoarthritis. The meniscal substitution strategies for advancing reconstruction of the meniscus deserve further investigation. HYPOTHESIS: A decellularized meniscal scaffold (DMS) modified with collagen affinity stromal cell-derived factor (C-SDF1α) may facilitate meniscal regeneration and protect cartilage from abrasion. STUDY DESIGN: Controlled laboratory study. METHODS: The authors first modified DMS with C-SDF1α to fabricate a new meniscal graft (DMS-CBD [collagen-binding domain]). Second, they performed in vitro studies to evaluate the release dynamics, biocompatibility, and differentiation inducibility (osteogenic, chondrogenic, and tenogenic differentiation) on human bone marrow mesenchymal stem cells. Using in vivo studies, they subjected rabbits that received medial meniscectomy to a transplantation procedure to implement their meniscal graft. At postoperative weeks 6 and 12, the meniscal regeneration outcomes and chondroprotective efficacy of the new meniscal graft were evaluated by macroscopic observation, histology, micromechanics, and immunohistochemistry tests. RESULTS: In in vitro studies, the optimized DMS-CBD graft showed notable biocompatibility, releasing efficiency, and chondrogenic inducibility. In in vivo studies, the implanted DMS-CBD graft after total meniscectomy promoted the migration of cells and extracellular matrix deposition in transplantation and further facilitated meniscal regeneration and protected articular cartilage from degeneration. CONCLUSION: The new meniscal graft (DMS-CBD) accelerated extracellular matrix deposition and meniscal regeneration and protected articular cartilage from degeneration. CLINICAL RELEVANCE: The results demonstrate that the DMS-CBD graft can serve as a potential meniscal substitution after meniscectomy.

Three Birds, One Stone: An Osteo-Microenvironment Stage-Regulative Scaffold for Bone Defect Repair through Modulating Early Osteo-Immunomodulation, Middle Neovascularization, and Later Osteogenesis.

In order to repair critical-sized bone defects, various polylactic acid-glycolic acid (PLGA)-based hybrid scaffolds are successfully developed as bone substitutes. However, the byproducts of these PLGA-based scaffolds are known to acidify the implanted site, inducing tiresome acidic inflammation. Moreover, these degradation productions cannot offer an osteo-friendly microenvironment at the implanted site, matching natural bone healing. Herein, inspired by bone microenvironment atlas of natural bone-healing process, an osteo-microenvironment stage-regulative scaffold (P80/D10/M10) is fabricated by incorporating self-developed decellularized bone matrix microparticles (DBM-MPs) and multifunctional magnesium hydroxide nanoparticles (MH-NPs) into PLGA with an optimized proportion using low-temperature rapid prototyping (LT-RP) 3D-printing technology. The cell experiments show that this P80/D10/M10 exhibits excellent properties in mechanics, biocompatibility, and biodegradability, meanwhile superior stimulations in osteo-immunomodulation, angiogenesis, and osteogenesis. Additionally, the animal experiments determined that this P80/D10/M10 can offer an osteo-friendly microenvironment in a stage-matched pattern for enhanced bone regeneration, namely, optimization of early inflammation, middle neovascularization, and later bone formation. Furthermore, transcriptomic analysis suggested that the in vivo performance of P80/D10/M10 on bone defect repair is mostly attributed to regulating artery development, bone development, and bone remodeling. Overall, this study reveals that the osteo-microenvironment stage-regulative scaffold provides a promising treatment for bone defect repair.