Biomimetic Nanofibrillar Hydrogel with Cell-Adaptable Network for Enhancing Cellular Mechanotransduction, Metabolic Energetics, and Bone Regeneration.

The natural extracellular matrix, with its heterogeneous structure, provides a stable and dynamic biophysical framework and biochemical signals to guide cellular behaviors. It is challenging but highly desirable to develop a synthetic matrix that emulates the heterogeneous fibrous structure with macroscopic stability and microscopical dynamics and contains inductive biochemical signals. Herein, we introduce a peptide fiber-reinforced hydrogel in which the stiff ß-sheet fiber functions as a multivalent cross-linker to enhance the hydrogel's macroscopic stability. The dynamic imine cross-link between the peptide fiber and polymer network endows the hydrogel with a microscopically dynamic network. The obtained fibrillar nanocomposite hydrogel, with its cell-adaptable dynamic network, enhances cell-matrix and cell-cell interactions and therefore significantly promotes the mechanotransduction, metabolic energetics, and osteogenesis of encapsulated stem cells. Furthermore, the hydrogel can codeliver a fiber-attached inductive drug to further enhance osteogenesis and bone regeneration. We believe that our work provides valuable guidance for the design of cell-adaptive and bioactive biomaterials for therapeutic applications.

Long Non-Coding RNA Malat1 Increases the Rescuing Effect of Quercetin on TNFα-Impaired Bone Marrow Stem Cell Osteogenesis and Ovariectomy-Induced Osteoporosis.

Osteoporosis, a common systematic bone homeostasis disorder related disease, still urgently needs innovative treatment methods. Several natural small molecules were found to be effective therapeutics in osteoporosis. In the present study, quercetin was screened out from a library of natural small molecular compounds by a dual luciferase reporter system. Quercetin was found to upregulate Wnt/ß-catenin while inhibiting NF-κB signaling activities, and thereby rescuing osteoporosis-induced tumor necrosis factor alpha (TNFα) impaired BMSCs osteogenesis. Furthermore, a putative functional lncRNA, Malat1, was shown to be a key mediator in quercetin regulated signaling activities and TNFα-impaired BMSCs osteogenesis, as mentioned above. In an ovariectomy (OVX)-induced osteoporosis mouse model, quercetin administration could significantly rescue OVX-induced bone loss and structure deterioration. Serum levels of Malat1 were also obviously rescued in the OVX model after quercetin treatment. In conclusion, our study demonstrated that quercetin could rescue TNFα-impaired BMSCs osteogenesis in vitro and osteoporosis-induced bone loss in vivo, in a Malat1-dependent manner, suggesting that quercetin may serve as a therapeutic candidate for osteoporosis treatment.

Formononetin Inhibits Mast Cell Degranulation to Ameliorate Compound 48/80-Induced Pseudoallergic Reactions.

Formononetin (FNT) is a plant-derived isoflavone natural product with anti-inflammatory, antioxidant, and anti-allergic properties. We showed previously that FNT inhibits immunoglobulin E (IgE)-dependent mast cell (MC) activation, but the effect of FNT on IgE-independent MC activation is yet unknown. Our aim was to investigate the effects and possible mechanisms of action of FNT on IgE-independent MC activation and pseudoallergic inflammation. We studied the effects of FNT on MC degranulation in vitro with a cell culture model using compound C48/80 to stimulate either mouse bone marrow-derived mast cells (BMMCs) or RBL-2H3 cells. We subsequently measured ß-hexosaminase and histamine release, the expression of inflammatory factors, cell morphological changes, and changes in NF-κB signaling. We also studied the effects of FNT in several in vivo murine models of allergic reaction: C48/80-mediated passive cutaneous anaphylaxis (PCA), active systemic anaphylaxis (ASA), and 2,4-dinitrobenzene (DNCB)-induced atopic dermatitis (AD). The results showed that FNT inhibited IgE-independent degranulation of MCs, evaluated by a decrease in the release of ß-hexosaminase and histamine and a decreased expression of inflammatory factors. Additionally, FNT reduced cytomorphological elongation and F-actin reorganization and attenuated NF-κB p65 phosphorylation and NF-κB-dependent promoter activity. Moreover, the administration of FNT alleviated pseudoallergic responses in vivo in mouse models of C48/80-stimulated PCA and ASA, and DNCB-induced AD. In conclusion, we suggest that FNT may be a novel anti-allergic drug with great potential to alleviate pseudoallergic responses via the inhibition of IgE-independent MC degranulation and NF-κB signaling.

Cranial Bone Transport Promotes Angiogenesis, Neurogenesis, and Modulates Meningeal Lymphatic Function in Middle Cerebral Artery Occlusion Rats.

BACKGROUND: Ischemic stroke is a leading cause of death and disability worldwide. However, the time window for quickly dissolving clots and restoring cerebral blood flow, using tissue-type plasminogen activator treatment is rather limited, resulting in many patients experiencing long-term functional impairments if not death. This study aims to determine the roles of cranial bone transport (CBT), a novel, effective, and simple surgical technique, in the recovery of ischemic stroke using middle cerebral artery occlusion (MCAO) rat model. METHODS: CBT was performed by slowly sliding a bone segment in skull with a special frame and a speed of 0.25 mm/12 hours for 10 days following MCAO. Morris water maze, rotarod test, and catwalk gait analysis were used to study the neurological behaviors, and infarct area and cerebral flow were evaluated during CBT process. Immunofluorescence staining of CD31 and Nestin/Sox2 (sex determining region Y box 2) was performed to study the angiogenesis and neurogenesis. OVA-A647 (ovalbumin-Alexa Fluor 647) was intracisterna magna injected to evaluate the meningeal lymphatic drainage function. RESULTS: CBT treatment has significantly reduced the ischemic lesions areas and improved the neurological deficits in MCAO rats compared with the rats in the control groups. CBT treatment significantly promoted angiogenesis and neurogenesis in the brain of MCAO rats. The drainage function of meningeal lymphatic vessels in MCAO rats was significantly impaired compared with normal rats. Ablation of meningeal lymphatic drainage led to increased neuroinflammation and aggravated neurological deficits and ischemic injury in MCAO rats. CBT treatment significantly improved the meningeal lymphatic drainage function and alleviated T-cell infiltration in MCAO rats. CONCLUSIONS: This study provided evidence for the possible mechanisms on how CBT attenuates ischemic stroke injury and facilitates rapid neuronal function recovery, suggesting that CBT may be an alternative treatment strategy for managing ischemic stroke.

Alleviation of osteoarthritis by intra-articular transplantation of circulating mesenchymal stem cells.

This study aimed to evaluate the efficacy of intra-articular delivery of peripheral blood derived mesenchymal stromal cells (PB-MSCs) on the progression of trauma-induced osteoarthritis (OA) in mice. Adult male C57BL/6J mice subjected to destabilization of the medial meniscus surgeries (DMM) were randomly divided into four groups: sham surgery group; vehicle control group (treated with saline), PBMSC-treated group, or adipose tissue derived MSCs (AD-MSC)-treated group (n = 4 per group). PB-MSCs and AD-MSCs were harvested and cultured following previously established protocols, and pre-labeled with BrdU for 48 h before transplantation. PB-MSCs or AD-MSCs (5 × 105 cells/mouse; passage 3-5) were intra-articular injected into the right knee joints thrice post-surgery. The mice were euthanized at 8 weeks post-surgery and knee joint samples were collected for micro-CT and histological examinations. PB-MSCs administration significantly reduced subchondral bone volume comparing to the vehicle control group. Safranin O staining showed that PB-MSCs treatment ameliorated degeneration of articular cartilage, which was comparable to AD-MSCs treatment. The expression of catabolic marker MMP13 was significantly reduced in articular cartilage of the PB-MSCs treated group comparing to that of the vehicle control group. Co-expression of BrdU and Sox9 indicated that injected PB-MSCs differentiated in chondrocytes in situ, along with reduced levels of IL-6 within peripheral sera of PB-MSCs- and AD-MSCs-treated mice. Therefore, administration of PB-MSCs or AD-MSCs attenuated trauma-induced OA progression through inhibiting cartilage degradation and inflammation. PB-MSCs are ideal cell source for treating cartilage-associated diseases.

Local administration of allogeneic or autologous bone marrow-derived mesenchymal stromal cells enhances bone formation similarly in distraction osteogenesis.

BACKGROUND AIMS: Distraction osteogenesis (DO) is a surgical technique to promote bone regeneration that requires a long time for bone healing. Bone marrow-derived mesenchymal stromal cells (MSCs) have been applied to accelerate bone formation in DO. Allogeneic MSCs are attractive, as they could be ready to use in clinics. Whether allogeneic MSCs would have an effect similar to autologous MSCs with regard to promoting bone formation in DO is still unknown. This study compares the effect of autologous MSCs versus allogeneic MSCs on bone formation in a rat DO model. METHODS: Rat bone marrow-derived MSCs were isolated, characterized and expanded in vitro. Adult rats were subjected to right tibia transverse osteotomy. On the third day of distraction, each rat received one injection of phosphate-buffered saline (PBS), autologous MSCs or allogeneic MSCs at the distraction site. Tibiae were harvested after 28 days of consolidation for micro-computed tomography examination, mechanical test and histological analysis. RESULTS: Results showed that treatment with both allogeneic and autologous MSCs promoted bone formation, with significantly higher bone mass, mechanical properties and mineral apposition rate as well as expression of angiogenic and bone formation markers at the regeneration sites compared with the PBS-treated group. No statistical difference in bone formation was found between the allogeneic and autologous MSC treatment groups. CONCLUSIONS: This study indicates that allogeneic and autologous MSCs have a similar effect on promoting bone consolidation in DO. MSCs from an allogeneic source could be used off-the-shelf with DO to achieve early bone healing.

Gold Nanoclusters for NIR-II Fluorescence Imaging of Bones.

Fluorescence imaging in the second near-infrared window (NIR-II, 1000-1700 nm) holds great promise for deep tissue visualization. Development of novel clinical translatable NIR-II probes is crucial for realizing the medical applications of NIR-II fluorescence imaging. Herein, the glutathione-capped gold nanoclusters (AuNCs, specifically Au25 (SG)18 ) demonstrate highly efficient binding capability to hydroxyapatite in vitro for the first time. Further in vivo NIR-II fluorescence imaging of AuNCs indicate that they accumulate in bone tissues with high contrast and signal-background ratio. AuNCs are also mainly and quickly excreted from body through renal system, showing excellent ribs and thoracic vertebra imaging because of no background signal in liver and spleen. The deep tissue penetration capability and high resolution of AuNCs in NIR-II imaging render their great potential for fluorescence-guided surgery like spinal pedicle screw implantation. Overall, AuNCs are highly promising and clinical translatable NIR-II imaging probe for visualizing bone and bone related abnormalities.

Lgr5-overexpressing mesenchymal stem cells augment fracture healing through regulation of Wnt/ERK signaling pathways and mitochondrial dynamics.

Fracture remains one of the most common traumatic conditions in orthopedic surgery. The use of mesenchymal stem cells (MSCs) to augment fracture repair is promising. Leucine-rich repeat-containing GPCR 5 (Lgr5), a transmembrane protein, has been identified as a novel adult stem cell marker in various organs and tissues. However, the roles of Lgr5 in MSCs are not fully understood. In this study, we investigated cellular functions of Lgr5 in MSCs and its potential implications in treating fracture. Lgr5-overexpressing MSCs (MSCLgr5) were established in murine SV40 promoter-driven luciferase reporter MSC line through virus transfection. Results of real-time quantitative PCR and Western blot analysis confirmed the increased expression of Lgr5 in MSCLgr5. MSCLgr5 exhibited increased osteogenic capacity, which may result from elevated expression of ß-catenin and phosphorylated ERK1/2 within the nuclear region of cells. In contrast, inhibition of Lgr5 expression decreased the osteogenic differentiation ability of MSCs, accompanied with increased mitochondrial fragmentation and reduced expression of ß-catenin. Local transplantation of MSCLgr5 at fracture sites accelerated fracture healing via enhanced osteogenesis and angiogenesis. MSCLgr5 stimulated the tube formation capacity of HUVECs in a Matrigel coculture system in vitro significantly. Taken together, results suggest that Lgr5 is implicated in the cellular processes of osteogenic differentiation of MSCs through regulation of Wnt and ERK signaling pathways and mitochondrial dynamics in fusion and fission. Inhibition of Lgr5 expression induced increased mitochondrial fragmentation and suppression of osteogenesis. MSCLgr5 exhibited enhanced therapeutic efficacy for fracture healing, which may serve as a superior cell source for bone tissue repair.-Lin, W., Xu, L., Pan, Q., Lin, S., Feng, L., Wang, B., Chen, S., Li, Y., Wang, H., Li, Y., Wang, Y., Lee, W. Y. W., Sun, D., Li, G. Lgr5-overexpressing mesenchymal stem cells augment fracture healing through regulation of Wnt/ERK signaling pathways and mitochondrial dynamics.

Sox11-modified mesenchymal stem cells accelerate cartilage defect repair in SD rats.

Cartilage has a limited capacity to heal. Previously, we have shown that overexpression of Sox11 in rMSCs (Rat Mesenchymal Stem Cells) by lentivirus-mediated gene transfer leads to enhanced tri-lineage differentiation and accelerated bone formation in fracture model of rats. We observed that the fracture repair in the rats that received Sox11-modified rMSCs injection proceeded through an endochondral ossification process much faster than those in the control groups. However, the detailed role of Sox11 in rMSCs chondrogenic differentiation, as well as cartilage defect, is still not clearly clarified. Therefore, this study tests the hypothesis that Sox11 promotes chondrogenesis and cartilage defect repair by regulating ß-catenin. Sox11 was transduced into rMSCs using lentiviruses. The expression levels of ß-catenin and its downstream genes were evaluated by quantitative RT-PCR. The transcriptional activation of ß-catenin was proved by dual-luciferase reporter assay and co-immunoprecipitation was performed to evaluate Sox11-ß-catenin interaction. In addition, a cartilage defect model in SD rats was used to evaluate the cartilage regeneration ability of Sox11-modified rMSCs in vivo. We found that Sox11 transcriptionally activated ß-catenin expression and discovered the core promoter region (from - 242 to - 1414) of ß-catenin gene for Sox11 binding. In addition, Sox11 might regulate ß-catenin at the post-transcriptional level by protein-protein interaction. Finally, using a cartilage defect model in rats, we found Sox11-modified rMSCs could improve cartilage regeneration. Taken together, our study shows that Sox11 is an important regulator of chondrogenesis and Sox11-modified rMSCs may have clinical implication for accelerating cartilage defect healing.

Asiatic Acid Attenuates Bone Loss by Regulating Osteoclastic Differentiation.

Anti-resorptive agents like bisphosphonates have been widely used for the treatment of postmenopausal osteoporosis. However, their long-term safety and efficacy are still controversial. This study is to examine the effect of Asiatic acid (AA) in osteoclastic differentiation, and further to investigate its effect on bone quality in animals. Effect of AA on osteoclastic differentiation was measured by Tartrate-resistant acid phosphatase stain, bone resorption pit assays, and quantitative real-time polymerase chain reaction. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and transforming growth factor-ß (TGF-ß) signaling were measured by western blot before and after AA treatment. Ovariectomized (OVX) wild-type or Smad7 partially knock out mice were used to evaluate the effects of AA on bone quality by micro-computed tomography, mechanical test, and histomorphometry. Results revealed a dose-dependent inhibitory effect of AA on osteoclastic differentiation. After AA treatment, Smad7 was upregulated, while NF-κB and TGF-ß signaling were inhibited during osteoclastic differentiation. Results from animal study revealed that AA prevented bone from further loss caused by OVX and increased the mechanical properties of femur in wild-type animals. AA also prevented bone loss in the Smad7-deficient animals. When combining with OVX in the Smad7-deficient mice, AA could only partially preserve their bone mass. Taken together, we found that AA effectively inhibited osteoclastic differentiation and attenuated osteoporosis, which effects may be through TGF-ß and NF-κB pathways. This study reveals that AA may be a potential anti-resorptive agent for postmenopausal osteoporosis.

Remote Control of Heterodimeric Magnetic Nanoswitch Regulates the Adhesion and Differentiation of Stem Cells.

Remote, noninvasive, and reversible control over the nanoscale presentation of bioactive ligands, such as Arg-Gly-Asp (RGD) peptide, is highly desirable for temporally regulating cellular functions in vivo. Herein, we present a novel strategy for physically uncaging RGD using a magnetic field that allows safe and deep tissue penetration. We developed a heterodimeric nanoswitch consisting of a magnetic nanocage (MNC) coupled to an underlying RGD-coated gold nanoparticle (AuNP) via a long flexible linker. Magnetically controlled movement of MNC relative to AuNP allowed reversible uncaging and caging of RGD that modulate physical accessibility of RGD for integrin binding, thereby regulating stem cell adhesion, both in vitro and in vivo. Reversible RGD uncaging by the magnetic nanoswitch allowed temporal regulation of stem cell adhesion, differentiation, and mechanosensing. This physical and reversible RGD uncaging utilizing heterodimeric magnetic nanoswitch is unprecedented and holds promise in the remote control of cellular behaviors in vivo.

Bioadhesive Polymersome for Localized and Sustained Drug Delivery at Pathological Sites with Harsh Enzymatic and Fluidic Environment via Supramolecular Host-Guest Complexation.

Targeted and sustained delivery of drugs to diseased tissues/organs, where body fluid exchange and catabolic activity are substantial, is challenging due to the fast cleansing and degradation of the drugs by these harsh environmental factors. Herein, a multifunctional and bioadhesive polycaprolactone-ß-cyclodextrin (PCL-CD) polymersome is developed for localized and sustained co-delivery of hydrophilic and hydrophobic drug molecules. This PCL-CD polymersome affords multivalent crosslinking action via surface CD-mediated host-guest interactions to generate a supramolecular hydrogel that exhibits evident shear thinning and efficient self-healing behavior. The co-delivery of small molecule and proteinaceous agents by the encapsulated PCL-CD polymersomes enhances the differentiation of stem cells seeded in the hydrogel. Furthermore, the PCL-CD polymersomes are capable of in situ grafting to biological tissues via host-guest complexation between surface CD and native guest groups in the tissue matrix both in vitro and in vivo, thereby effectively extending the retention of loaded cargo in the grafted tissue. It is further demonstrated that the co-delivery of small molecule and proteinaceous drugs via PCL-CD polymersomes averts cartilage degeneration in animal osteoarthritic (OA) knee joints, which are known for their biochemically harsh and fluidically dynamic environment.

Remote Manipulation of Ligand Nano-Oscillations Regulates Adhesion and Polarization of Macrophages in Vivo.

Macrophages play crucial roles in various immune-related responses, such as host defense, wound healing, disease progression, and tissue regeneration. Macrophages perform distinct and dynamic functions in vivo, depending on their polarization states, such as the pro-inflammatory M1 phenotype and pro-healing M2 phenotype. Remote manipulation of the adhesion of host macrophages to the implants and their subsequent polarization in vivo can be an attractive strategy to control macrophage polarization-specific functions but has rarely been achieved. In this study, we grafted RGD ligand-bearing superparamagnetic iron oxide nanoparticles (SPIONs) to a planar matrix via a long flexible linker. We characterized the nanoscale motion of the RGD-bearing SPIONs grafted to the matrix, in real time by in situ magnetic scanning transmission electron microscopy (STEM) and in situ atomic force microscopy. The magnetic field was applied at various oscillation frequencies to manipulate the frequency-dependent ligand nano-oscillation speeds of the RGD-bearing SPIONs. We demonstrate that a low oscillation frequency of the magnetic field stimulated the adhesion and M2 polarization of macrophages, whereas a high oscillation frequency suppressed the adhesion of macrophages but promoted their M1 polarization, both in vitro and in vivo. Macrophage adhesion was also temporally regulated by switching between the low and high frequencies of the oscillating magnetic field. To the best of our knowledge, this is the first demonstration of the remote manipulation of the adhesion and polarization phenotype of macrophages, both in vitro and in vivo. Our system offers the promising potential to manipulate host immune responses to implanted biomaterials, including inflammation or tissue reparative processes, by regulating macrophage adhesion and polarization.

U0126 promotes osteogenesis of rat bone-marrow-derived mesenchymal stem cells by activating BMP/Smad signaling pathway.

U0126 has been reported as a specific inhibitor of the ERK1/2 signaling pathway, which plays a vital role during the osteogenic differentiation of mesenchymal stem cells (MSCs). We report the positive effect of U0126 on the osteogenesis of rat MSCs. We find that U0126 promotes the osteogenic differentiation of rat MSCs as demonstrated by the quantitative real-time polymerase chain reaction for osteogenic markers, alkaline phosphatase activity and calcium nodule formation. Our data indicate that U0126 enhances the BMP/Smad signaling pathway in rat MSCs, while inhibiting the ERK1/2 signaling pathway. Furthermore, Western blot results demonstrate that U0126 increases Smad1/5/8 phosphorylation synergistically with ß-glycerophosphate. In addition, U0126 significantly increases the expression of BMP2 during the process of osteogenesis in rat MSCs and the level of phosphorylated Smad1/5/8 is significantly reduced by BMP2 antibody, suggesting that U0126 also promotes the expression of BMP2 to enhance Smad proteins phosphorylation. Thus, we demonstrate a novel function for U0126 in promoting osteogenic differentiation of rat MSCs by the activation of the BMP/Smad signaling pathway.

The effects of atorvastatin on the prevention of osteoporosis and dyslipidemia in the high-fat-fed ovariectomized rats.

Previous studies reported that statins showed positive effects on bone in both human and animal models. This study aimed to investigate the effects of atorvastatin on the prevention of osteoporosis and dyslipidemia in ovariectomized rats fed with high-fat emulsion. The 3-month-old female rats were subjected to either sham operations (n = 8) or ovariectomized operations (OVX, n = 24). The OVX rats were orally administered deionized water (n = 8) or standardized high-fat emulsion without (n = 8) or with atorvastatin (n = 8). All rats were injected twice with calcein before sacrificed for the purpose of double in vivo labeling. After 12 weeks, all rats were sacrificed under anesthesia. Biochemistry, histomorphometry, mechanical test, micro-computed tomography analysis, mechanical test, histology, and component analysis were performed. We found that high-fat emulsion significantly decreased body weight, bone formation, collagen content of bone, and bone biomechanics, while increased blood, liver, and bone marrow lipids. Atorvastatin treatment prevented dyslipidemia, reversed hepatic steatosis, optimized composition of bone, and improved bone mechanical properties. The current study provided further evidence that atorvastatin might be useful for the treatment of osteoporotic patients with dyslipidemia.

Glucocorticoid-induced osteoporosis in growing rats.

This study evaluated whether growing rats were appropriate animal models of glucocorticoid-induced osteoporosis. The 3-month-old male rats were treated with either vehicle or prednisone acetate at 1.5, 3.0, and 6.0 mg/kg/day by oral gavage, respectively. All rats were injected with tetracycline and calcein before sacrificed for the purpose of double in vivo labeling. Biochemistry, histomorphometry, mechanical test, densitometry, micro-CT, histology, and component analysis were performed. We found that prednisone treatments dose dependently decreased body weight, serum biomarkers, biomechanical markers, bone formation, and bone resorption parameters in both tibial and femoral trabecular bone without trabecular bone loss. We also found that significant bone loss happened in femoral cortical bone in the glucocorticoid-treated rats. The results suggested that prednisone not only inhibited bone formation, but also inhibited bone resorption which resulted in poor bone strength but with no cancellous bone loss in growing rats. These data also suggested that the effects of glucocorticoid on bone metabolism were different between cortical bone and trabecular bone, and different between tibia and femur. Growing rats may be a glucocorticoid-induced osteoporosis animal model when evaluated the effects of drugs upon juvenile patients exposed to GC for a long time.

In Vivo Effect of Single Intra-Articular Injection of Tranexamic Acid on Articular Cartilage and Meniscus: Study in a Rat Model.

BACKGROUND: Tranexamic acid (TXA) has been increasingly used in arthroscopic surgery to prevent hemarthrosis. Despite its effectiveness, safety concerns have been raised regarding its potential cytotoxicity to articular cartilage and meniscus following intra-articular injection. METHODS: To evaluate the impact of TXA on cartilage and meniscus, a rat model of knee instability was utilized wherein anterior cruciate ligament (ACL) transection surgery was followed by a single intra-articular injection of TXA at varying concentrations (0, 20, 50, 100, and 150 mg/mL) in saline solution. Cell viability assessment of the cartilage and meniscus (n = 6 per group) was conducted at 24 hours, and gross observation and histological analysis of the medial tibial plateau and medial meniscus were conducted at 2, 4, and 8 weeks (n = 6 per group and time point). RESULTS: The chondrocyte viability was significantly decreased in the 50, 100, and 150 mg/mL TXA groups compared with the specimens injected with saline solution only (saline group) (p = 0.001, p < 0.001, p < 0.001, respectively), as was meniscal cell viability (p = 0.042, p < 0.001, p < 0.001, respectively). At week 8, the saline and 20 and 50 mg/mL groups showed relatively normal appearances, whereas the 100 and 150 mg/mL groups exhibited increased and varying severity of cartilage and meniscal degeneration. In the 150 mg/mL group, the mean Osteoarthritis Research Society International score was significantly higher than that in the saline and 20 mg/mL groups (p = 0.010 and p = 0.007). Additionally, the mean meniscus score in the 150 mg/mL group was significantly higher than that in the saline, 20 mg/mL, and 50 mg/mL groups (p = 0.020, p = 0.021, p = 0.031, respectively). CONCLUSIONS: Our findings indicate that concentrations of TXA at or above 100 mg/mL can lead to decreased cell viability in both cartilage and meniscus, resulting in significant cartilage degeneration in rats with ACL transection. Furthermore, the use of 150 mg/mL of TXA led to significant meniscal degeneration. CLINICAL RELEVANCE: It is prudent to avoid using concentrations of TXA at or above 100 mg/mL for intra-articular injection, as such concentrations may result in adverse effects on the cartilage and meniscus.

Activated allograft combined with induced menbrane technique for the reconstruction of infected segmental bone defects.

This study was desinged to evaluate the efficacy and safety of activated allograft combined with the induced membrane technique for reconstruction of infected segment bone defects of lower limbs. A retrospective analysis was conducted on 19 patients from May 2015 to February 2017. After debridements, the bone defects were filled with antibiotic bone cement to form the induced membrane. Autologous mesenchymal stem cells were seeded onto allografts to construct activated allograft, which was implanted into the induced membrane after infection was controlled. The clinical efficacy and complications were observed. 19 patients with 20 infected segment bone defect were evaluated. The average deficit size was 11.08 (4-17) cm in length. After a mean follow-up of 71.84 (61-82) months, bone union was achieved in 16 patients (17 sites), resulting in a final union rate of 84.21% (16/19 patients). The average bone union time was 10.18 (5-28) months. There were 2 patients with recurrence of infection, 3 patients with graft absorption, and 1 patient with malunion due to implant breakage. There were no graft-related complications. This study provides clinical significance for the treatment of patients with insufficient autologous bone.

Advancing skeletal health and disease research with single-cell RNA sequencing.

Orthopedic conditions have emerged as global health concerns, impacting approximately 1.7 billion individuals worldwide. However, the limited understanding of the underlying pathological processes at the cellular and molecular level has hindered the development of comprehensive treatment options for these disorders. The advent of single-cell RNA sequencing (scRNA-seq) technology has revolutionized biomedical research by enabling detailed examination of cellular and molecular diversity. Nevertheless, investigating mechanisms at the single-cell level in highly mineralized skeletal tissue poses technical challenges. In this comprehensive review, we present a streamlined approach to obtaining high-quality single cells from skeletal tissue and provide an overview of existing scRNA-seq technologies employed in skeletal studies along with practical bioinformatic analysis pipelines. By utilizing these methodologies, crucial insights into the developmental dynamics, maintenance of homeostasis, and pathological processes involved in spine, joint, bone, muscle, and tendon disorders have been uncovered. Specifically focusing on the joint diseases of degenerative disc disease, osteoarthritis, and rheumatoid arthritis using scRNA-seq has provided novel insights and a more nuanced comprehension. These findings have paved the way for discovering novel therapeutic targets that offer potential benefits to patients suffering from diverse skeletal disorders.

Glucocorticoid induced bone disorders in children: Research progress in treatment mechanisms.

Long-term or supra-physiological dose of glucocorticoid (GC) application in clinic can lead to impaired bone growth and osteoporosis. The side effects of GC on the skeletal system are particularly serious in growing children, potentially causing growth retardation or even osteoporotic fractures. Children's bone growth is dependent on endochondral ossification of growth plate chondrocytes, and excessive GC can hinder the development of growth plate and longitudinal bone growth. Despite the availability of drugs for treating osteoporosis, they have failed to effectively prevent or treat longitudinal bone growth and development disorders caused by GCs. As of now, there is no specific drug to mitigate these severe side effects. Traditional Chinese Medicine shows potential as an alternative to the current treatments by eliminating the side effects of GC. In summary, this article comprehensively reviews the research frontiers concerning growth and development disorders resulting from supra-physiological levels of GC and discusses the future research and treatment directions for optimizing steroid therapy. This article may also provide theoretical and experimental insight into the research and development of novel drugs to prevent GC-related side effects.