Systemically administered zoledronic acid activates locally implanted synthetic hydroxyapatite particles enhancing peri-implant bone formation: A regenerative medicine approach to improve fracture fixation.

Fracture fixation in an ageing population is challenging and fixation failure increases mortality and societal costs. We report a novel fracture fixation treatment by applying a hydroxyapatite (HA) based biomaterial at the bone-implant interface and biologically activating the biomaterial by systemic administration of a bisphosphonate (zoledronic acid, ZA). We first used an animal model of implant integration and applied a calcium sulphate (CaS)/HA biomaterial around a metallic screw in the tibia of osteoporotic rats. Using systemic ZA administration at 2-weeks post-surgery, we demonstrated that the implant surrounded by HA particles showed significantly higher peri­implant bone formation compared to the unaugmented implants at 6-weeks. We then evaluated the optimal timing (day 1, 3, 7 and 14) of ZA administration to achieve a robust effect on peri­implant bone formation. Using fluorescent ZA, we demonstrated that the uptake of ZA in the CaS/HA material was the highest at 3- and 7-days post-implantation and the uptake kinetics had a profound effect on the eventual peri­implant bone formation. We furthered our concept in a feasibility study on trochanteric fracture patients randomized to either CaS/HA augmentation or no augmentation followed by systemic ZA treatment. Radiographically, the CaS/HA group showed signs of increased peri­implant bone formation compared with the controls. Finally, apart from HA, we demonstrated that the concept of biologically activating a ceramic material by ZA could also be applied to ß-tricalcium phosphate. This novel approach for fracture treatment that enhances immediate and long-term fracture fixation in osteoporotic bone could potentially reduce reoperations, morbidity and mortality. STATEMENT OF SIGNIFICANCE: • Fracture fixation in an ageing population is challenging. Biomaterial-based augmentation of fracture fixation devices has been attempted but lack of satisfactory biological response limits their widespread use. • We report the biological activation of locally implanted microparticulate hydroxyapatite (HA) particles placed around an implant by systemic administration of the bisphosphonate zoledronic acid (ZA). The biological activation of HA by ZA enhances peri­implant bone formation. •Timing of ZA administration after HA implantation is critical for optimal ZA uptake and consequently determines the extent of peri­implant bone formation. • We translate the developed concept from small animal models of implant integration to a proof-of-concept clinical study on osteoporotic trochanteric fracture patients. • ZA based biological activation can also be applied to other calcium phosphate biomaterials.

Conditional knockout of PDK1 in osteoclasts suppressed osteoclastogenesis and ameliorated prostate cancer-induced osteolysis in murine model.

BACKGROUND: The development and maintenance of normal bone tissue is maintained by balanced communication between osteoblasts and osteoclasts. The invasion of cancer cells disrupts this balance, leading to osteolysis. As the only bone resorbing cells in vivo, osteoclasts play important roles in cancer-induced osteolysis. However, the role of 3-phosphoinositide-dependent protein kinase-1 (PDK1) in osteoclast resorption remains unclear. METHODS: In our study, we used a receptor activator of nuclear factor-kappa B (RANK) promoter-driven Cre-LoxP system to conditionally delete the PDK1 gene in osteoclasts in mice. We observed the effect of osteoclast-specific knockout of PDK1 on prostate cancer-induced osteolysis. Bone marrow-derived macrophage cells (BMMs) were extracted and induced to differentiate osteoclasts in vitro to explore the role of PDK1 in osteoclasts. RESULTS: In this study, we found that PDK1 conditional knockout (cKO) mice exhibited smaller body sizes when compared to the wild-type (WT) mice. Moreover, deletion of PDK1 in osteoclasts ameliorated osteolysis and rPDK1educed bone resorption markers in the murine model of prostate cancer-induced osteolysis. In vivo, we discovered that osteoclast-specific knockout of suppressed RANKL-induced osteoclastogenesis, bone resorption function, and osteoclast-specific gene expression (Ctsk, TRAP, MMP-9, NFATc1). Western blot analyses of RANKL-induced signaling pathways showed that conditional knockout of PDK1 in osteoclasts inhibited the early nuclear factor κB (NF-κB) activation, which consequently suppressed the downstream induction of NFATc1. CONCLUSION: These findings demonstrated that PDK1 performs an important role in osteoclastogenesis and prostate cancer-induced osteolysis by modulating the PDK1/AKT/NF-κB signaling pathway.

Short-chain fatty acids ameliorate spinal cord injury recovery by regulating the balance of regulatory T cells and effector IL-17+ γδ T cells. / çŸ­é“¾è„‚è‚ªé ¸é€šè¿‡è°ƒèŠ‚è°ƒèŠ‚æ€§T细胞和IL-17+ γδ T细胞的平衡来改善脊髓损伤的恢复.

Spinal cord injury (SCI) causes motor, sensory, and autonomic dysfunctions. The gut microbiome has an important role in SCI, while short-chain fatty acids (SCFAs) are one of the main bioactive mediators of microbiota. In the present study, we explored the effects of oral administration of exogenous SCFAs on the recovery of locomotor function and tissue repair in SCI. Allen's method was utilized to establish an SCI model in Sprague-Dawley (SD) rats. The animals received water containing a mixture of 150 mmol/L SCFAs after SCI. After 21 d of treatment, the Basso, Beattie, and Bresnahan (BBB) score increased, the regularity index improved, and the base of support (BOS) value declined. Spinal cord tissue inflammatory infiltration was alleviated, the spinal cord necrosis cavity was reduced, and the numbers of motor neurons and Nissl bodies were elevated. Enzyme-linked immunosorbent assay (ELISA), real-time quantitative polymerase chain reaction (qPCR), and immunohistochemistry assay revealed that the expression of interleukin (IL)|-10 increased and that of IL-17 decreased in the spinal cord. SCFAs promoted gut homeostasis, induced intestinal T cells to shift toward an anti-inflammatory phenotype, and promoted regulatory T (Treg) cells to secrete IL-10, affecting Treg cells and IL-17+ γδ T cells in the spinal cord. Furthermore, we observed that Treg cells migrated from the gut to the spinal cord region after SCI. The above findings confirm that SCFAs can regulate Treg cells in the gut and affect the balance of Treg and IL-17+ γδ T cells in the spinal cord, which inhibits the inflammatory response and promotes the motor function in SCI rats. Our findings suggest that there is a relationship among gut, spinal cord, and immune cells, and the "gut-spinal cord-immune" axis may be one of the mechanisms regulating neural repair after SCI.

[Application of different puncture techniques to inject bone cement in osteoporotic vertebral compression fractures].

OBJECTIVE: To study the application of different puncture techniques to inject bone cement in osteoporotic vertebral compression fractures (OVCFs). METHODS: The clinical data of 282 patients with OVCFs treated from January 2017 to December 2019 were collected for a retrospective study. According to the surgical plan the patients were divided into group A and B, with 141 cases in each group. In group A, extreme lateral puncture was used to inject bone cement through unilateral puncture and bilateral puncture. In group B, bone cement was injected through unilateral pedicle puncture through pedicle approach. The operation status(operation time, radiation exposure time, bone cement injection volume, hospital stay) and complications were observed between two groups. Before operation and 6, 12 months after operation, the pain mediators such as serotonin 5-hydroxytryptamine (5-HT), prostaglandin E2(PGE2), substance P(SP) were compared, bone mineral density, anatomical parameters of the injured vertebrae (height of the anterior edge of the vertebral body, height of the posterior edge of the vertebral body, Cobb angle), visual analogue scale (VAS) and Oswestry disability index (ODI) were evaluated between two groups. RESULTS: There were no significant difference in operation time, radiation exposure time, hospital stay between two groups (P>0.05). The amount of bone cement injected in group A was greater than that in group B (P<0.05). The serum 5-HT, SP and PGE2 levels of group A were lower than those of group B at 12 months after operation (P<0.05). The height of anterior edge and height of the posterior edge of vertebral body in group A were greater than those of group B at 12 months after operation, Cobb angle of group A was smaller than that of group B, VAS and ODI were lower than those of group B(P<0.05). There was no significant difference in bone mineral density between two groups at 6 and 12 months postoperatively(P<0.05). There was no significant difference between two groups in postoperative complications (P>0.05). CONCLUSION: Compared with unilateral puncture of the pedicle approach, unilateral puncture and bilateral cement injection technique is more conducive to the recovery of the injured vertebral anatomy and function, and do not prolong operation time, radiation exposure time, hospital stay, nor do increase the risk of nerve damage and bone cement leakage, and postoperative bone metabolism and bone mineral density are improved well, which is a safe and reliable surgical method for the treatment of OVCFs.

Changes in the gut microbiota of osteoporosis patients based on 16S rRNA gene sequencing: a systematic review and meta-analysis.

BACKGROUND: Osteoporosis (OP) has become a major public health issue, threatening the bone health of middle-aged and elderly people from all around the world. Changes in the gut microbiota (GM) are correlated with the maintenance of bone mass and bone quality. However, research results in this field remain highly controversial, and no systematic review or meta-analysis of the relationship between GM and OP has been conducted. This paper addresses this shortcoming, focusing on the difference in the GM abundance between OP patients and healthy controls based on previous 16S ribosomal RNA (rRNA) gene sequencing results, in order to provide new clinical reference information for future customized prevention and treatment options of OP. METHODS: According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), we comprehensively searched the databases of PubMed, Web of Science, Embase, Cochrane Library, and China National Knowledge Infrastructure (CNKI). In addition, we applied the R programming language version 4.0.3 and Stata 15.1 software for data analysis. We also implemented the Newcastle-Ottawa Scale (NOS), funnel plot analysis, sensitivity analysis, Egger's test, and Begg's test to assess the risk of bias. RESULTS: This research ultimately considered 12 studies, which included the fecal GM data of 2033 people (604 with OP and 1429 healthy controls). In the included research papers, it was observed that the relative abundance of Lactobacillus and Ruminococcus increased in the OP group, while the relative abundance for Bacteroides of Bacteroidetes increased (except for Ireland). Meanwhile, Firmicutes, Blautia, Alistipes, Megamonas, and Anaerostipes showed reduced relative abundance in Chinese studies. In the linear discriminant analysis Effect Size (LEfSe) analysis, certain bacteria showed statistically significant results consistently across different studies. CONCLUSIONS: This observational meta-analysis revealed that changes in the GM were correlated with OP, and variations in some advantageous GM might involve regional differences.

Total flavonoids of hawthorn leaves protect spinal motor neurons via promotion of autophagy after spinal cord injury.

The death of spinal motor neurons (SMNs) after spinal cord injury (SCI) is a crucial cause, contributing to a permanent neurological deficit. Total flavonoids of hawthorn leaves (TFHL) have been confirmed to have potentially therapeutic for SCI. Nonetheless, the roles and mechanisms of TFHL in recovering neuromotor function and regenerating axons of SMNs have not been fully elucidated. In this study, TFHL was applied to treat rats with SCI and injured SMNs for 7 days. In vivo experiment, rats with SCI were evaluated by a BBB (Basso-Beattie-Bresnahan) score to assess their motor functional recovery. The morphology, microstructure, apoptosis, Nissl bodies, and autophagy of SMNs in spinal cord tissue were detected by Hematoxylin-eosin (HE) staining, transmission electron microscopy, TUNEL staining, Nissl staining, and immunohistochemistry respectively. In vitro experiment, the co-culture model of SMNs and astrocytes was constructed to simulate the internal environment around SMNs in the spinal cord tissue. The cell morphology, microstructure, axonal regeneration, and autophagy were observed via optical microscope, transmission electron microscopy, and immunofluorescence. The content of neurotrophic factors in the cell culture medium of the co-culture model was detected by ELISA. Moreover, the expression of axon-related and autophagy-related proteins in the spinal cord tissue and SMNs was measured by Western Blot. We demonstrated that TFHL improved the neuromotor function recovery in rats after SCI. We then found that TFHL significantly promoted injured spinal cord tissue repair, reduced apoptosis, and improved the functional status of neurons in spinal cord tissue in vivo. Meanwhile, the cell morphology, microstructure, and axonal regeneration of damaged SMNs also obviously were improved, and the secretion of neurotrophic factors was facilitated after treatment with TFHL in vitro. Further, we revealed that TFHL promoted autophagy and related protein expression in vivo and vitro. Taken together, our study suggested that TFHL might facilitate autophagy and have neuroprotective properties in SMNs to enhance the recovery of neuromotor function of rats with SCI.

Adapalene Inhibits Prostate Cancer Cell Proliferation In Vitro and In Vivo by Inducing DNA Damage, S-phase Cell Cycle Arrest, and Apoptosis.

Aims: Prostate cancer is a well-known aggressive malignant tumor in men with a high metastasis rate and poor prognosis. Adapalene (ADA) is a third-generation synthetic retinoid with anticancer properties. We investigated the anti-tumor activity and molecular mechanisms of ADA in the RM-1 prostate cancer cell line in vivo and in vitro. Methods: The effects of ADA on cell proliferation were estimated using the CCK-8 and colony formation assays. The wound-healing assay and the Transwell assay were employed to examine the migratory capacity and invasiveness of the cells. Flow cytometry was utilized to evaluate the cell cycle and apoptosis, and Western blotting analysis was used to assess the expression of the associated proteins. Micro-CT, histomorphological, and immunohistochemical staining were used to assess the effects of ADA on bone tissue structure and tumor growth in a mouse model of prostate cancer bone metastasis. Result: ADA dramatically inhibited cell proliferation, migration, invasiveness, and induced S-phase arrest and apoptosis. ADA also regulated the expression of S-phase associated proteins and elevated the levels of DNA damage markers, p53, and p21 after ADA treatment, suggesting that the anti-tumor effect of ADA manifests through the DNA damage/p53 pathway. Furthermore, we observed that ADA could effectively inhibited tumor growth and bone destruction in mice. Conclusion: ADA inhibited prostate cancer cell proliferation, elicited apoptosis, and arrested the cell cycle in the S-phase. ADA also slowed the rate of tumor growth and bone destruction in vitro. Overall, our results suggest that ADA may be a potential treatment against prostate cancer.

Characteristics of Talaromyces marneffei with bone destruction in Guangxi Province, China: a retrospective study.

BACKGROUND AND OBJECTIVE: This study retrospectively analyzed the clinical and imaging features of TM mycosis complicated with bone destruction with the aim to improve understanding, diagnosis, and treatment. METHODS: Data of hospitalized TM-infected patients with bone destruction from October 2012 to May 2019 were collected. The clinical and imaging features of the disease were comprehensively analyzed. RESULTS: All 35 patients were non-HIV infected, but some had underlying co-morbid illnesses. The duration of the disease was 1-36 months (median: 5 months). Fever, anemia, weight loss, and respiratory symptoms were the main clinical manifestations of the patients. There were 18 patients (51.4%) who had bone pain. Peripheral blood leukocyte count increased significantly in 27 patients (77.1%). The neutrophil count increased in 28 patients (80%). C-reactive protein (CRP) and immunoglobulin G levels increased in 93.3% (14/15) and 82.1% (23/28) patients, respectively. The imaging examination showed osteolytic lesions, which were multiple in several bony areas. CONCLUSION: Young and middle-aged patients with non-AIDS TM complicated with underlying diseases should be especially cautious in case of occurrence of bone destruction. The main clinical manifestations of patients with TM complicated with bone destruction were pulmonary symptoms and bone and joint pain, which could be accompanied by progressive consumptive diseases.

Conditional knockout of the PDK-1 gene in osteoblasts affects osteoblast differentiation and bone formation.

Osteoblasts are the main functional cells of bone formation, and they are responsible for the synthesis, secretion, and mineralization of the bone matrix. Phosphatidylinositol-3-kinase/Akt is an important signaling pathway involved in the regulation of cell proliferation, death, and survival. Some studies have shown that 3-phosphoinositide-dependent protein kinase-1 (PDK-1) plays an important role in the phosphorylation of Akt. In the present study, an osteocalcin (OCN) promoter-driven Cre-LoxP system was established to specifically delete the PDK-1 gene in osteoblasts. It was found that the size and weight of PDK-1 conditional gene knockout (cKO) mice were significantly reduced. von Kossa staining and microcomputed tomography showed that the trabecular thickness, trabecular number, and bone volume were significantly decreased, whereas trabecular separation was increased, as compared with wide-type littermates, which were characterized by a decreased bone mass. A model of distal femoral defect was established, and it was found that cKO mice delayed bone defect repair. In osteoblasts derived from PDK-1 cKO mice, the alkaline phosphatase (ALP) secretion and ability of calcium mineralization were significantly decreased, and the expressions of osteoblast-related proteins, runt-related transcription factor 2, OCN, and ALP were also clearly decreased. Moreover, the phosphorylation level of Akt and downstream factor GSK3ß and their response to insulin-like growth factor-1 (IGF-1) decreased clearly. Therefore, we believe that PDK-1 plays a very important role in osteoblast differentiation and bone formation by regulating the PDK-1/Akt/GSK3ß signaling pathway.

Effects of inhibiting PDK­1 expression in bone marrow mesenchymal stem cells on osteoblast differentiation in vitro.

Osteoblasts are the main functional cells in bone formation, which are responsible for the synthesis, secretion and mineralization of bone matrix. The PI3K/AKT signaling pathway is strongly associated with the differentiation and survival of osteoblasts. The 3­phosphoinositide­dependent protein kinase­1 (PDK­1) protein is considered the master upstream lipid kinase of the PI3K/AKT cascade. The present study aimed to investigate the role of PDK­1 in the process of mouse osteoblast differentiation in vitro. In the BX­912 group, BX­912, a specific inhibitor of PDK­1, was added to osteoblast induction medium (OBM) to treat bone marrow mesenchymal stem cells (BMSCs), whereas the control group was treated with OBM alone. Homozygote PDK1flox/flox mice were designed and generated, and were used to obtain BMSCsPDK1flox/flox. Subsequently, an adenovirus containing Cre recombinase enzyme (pHBAd­cre­EGFP) was used to disrupt the PDK­1 gene in BMSCsPDK1flox/flox; this served as the pHBAd­cre­EGFP group and the efficiency of the disruption was verified. Western blot analysis demonstrated that the protein expression levels of phosphorylated (p)­PDK1 and p­AKT were gradually increased during the osteoblast differentiation process. Notably, BX­912 treatment and disruption of the PDK­1 gene with pHBAd­cre­EGFP effectively reduced the number of alkaline phosphatase (ALP)­positive cells and the optical density value of ALP activity, as well as the formation of cell mineralization. The mRNA expression levels of PDK­1 in the pHBAd­cre­EGFP group were significantly downregulated compared with those in the empty vector virus group on days 3­7. The mRNA expression levels of the osteoblast­related genes RUNX2, osteocalcin and collagen I were significantly decreased in the BX­912 and pHBAd­cre­EGFP groups on days 7 and 21 compared with those in the control and empty vector virus groups. Overall, the results indicated that BX­912 and disruption of the PDK­1 gene in vitro significantly inhibited the differentiation and maturation of osteoblasts. These experimental results provided an experimental and theoretical basis for the role of PDK­1 in osteoblasts.

Deficiency of PDK1 in osteoclasts delays fracture healing and repair.

Bone fractures are common traumatic injuries of the musculoskeletal system. However, delayed union and non­union fractures are a major clinical problem that present significant socioeconomic burden to patients and the public health sector. The bone­resorbing osteoclasts and bone­forming osteoblasts serve important roles in the fracture repair/healing process. Osteoclast deficiency or decreased osteoblast activity negatively impacts fracture healing. We previously demonstrated that the specific deletion of the serine/threonine kinase 3­phosphoinositide­dependent protein kinase 1 (PDK1) in osteoclasts leads to abrogated osteoclast formation and bone resorption in response to receptor activator of nuclear factor­κB in vitro and protected mice against ovariectomized­induced bone loss and lipopolysaccharide­induced osteolysis in vivo. Given the importance of osteoclasts in fracture repair, we hypothesized that the specific loss of PDK1 in osteoclasts will alter the fracture healing process. Mice of tibial fracture were constructed, and tibial specimens were sampled at 7­, 14­, 21­ and 28­days post­fracture to observe the effect of PDK1 gene regulated osteoclasts on fracture healing process by X­ray radiography, microcomputed tomography scanning, histomorphological staining and biomechanical testing. The present study revealed, using the tibial fracture model, that the specific deletion of the PDK1 gene in osteoclasts impeded the fracture healing process by delaying the resorption of the cartilaginous callus and subsequent remodeling of immature woven bone to structurally and mechanically ensure lamellar bone is stronger. No effect on osteoblast bone formation and osteogenesis was observed, thus indicating that delayed fracture healing is primarily due to defective osteoclast activity. These results provide important clinical implications for the use of anti­resorptive agents, such as bisphosphonates, for the treatment of osteolytic conditions. Such anti­resorptive therapies may detrimentally delay fracture healing and repair.

Adenovirus-mediated GDF-5 promotes the extracellular matrix expression in degenerative nucleus pulposus cells.

OBJECTIVE: To construct a recombinant adenovirus vector-carrying human growth and differentiation factor-5 (GDF-5) gene, investigate the biological effects of adenovirus-mediated GDF-5 (Ad-GDF-5) on extracellular matrix (ECM) expression in human degenerative disc nucleus pulposus (NP) cells, and explore a candidate gene therapy method for intervertebral disc degeneration (IDD). METHODS: Human NP cells of a degenerative disc were isolated, cultured, and infected with Ad-GDF-5 using the AdEasy-1 adenovirus vector system. On Days 3, 7, 14, and 21, the contents of the sulfated glycosaminoglycan (sGAG), deoxyribonucleic acid (DNA) and hydroxyproline (Hyp), synthesis of proteoglycan and collagen II, gene expression of collagen II and aggrecan, and NP cell proliferation were assessed. RESULTS: The adenovirus was an effective vehicle for gene delivery with prolonged expression of GDF-5. Biochemical analysis revealed increased sGAG and Hyp contents in human NP cells infected by Ad-GDF-5 whereas there was no conspicuous change in basal medium (BM) or Ad-green fluorescent protein (GFP) groups. Only cells in the Ad-GDF-5 group promoted the production of ECM, as demonstrated by the secretion of proteoglycan and up-regulation of collagen II and aggrecan at both protein and mRNA levels. The NP cell proliferation was significantly promoted. CONCLUSIONS: The data suggest that Ad-GDF-5 gene therapy is a potential treatment for IDD, which restores the functions of degenerative intervertebral disc through enhancing the ECM production of human NP cells.

Repair of articular cartilage defects in rabbits through tissue-engineered cartilage constructed with chitosan hydrogel and chondrocytes.

OBJECTIVE: In our previous work, we prepared a type of chitosan hydrogel with excellent biocompatibility. In this study, tissue-engineered cartilage constructed with this chitosan hydrogel and costal chondrocytes was used to repair the articular cartilage defects. METHODS: Chitosan hydrogels were prepared with a crosslinker formed by combining 1,6-diisocyanatohexane and polyethylene glycol. Chitosan hydrogel scaffold was seeded with rabbit chondrocytes that had been cultured for one week in vitro to form the preliminary tissue-engineered cartilage. This preliminary tissue-engineered cartilage was then transplanted into the defective rabbit articular cartilage. There were three treatment groups: the experimental group received preliminary tissue-engineered cartilage; the blank group received pure chitosan hydrogels; and, the control group had received no implantation. The knee joints were harvested at predetermined time. The repaired cartilage was analyzed through gross morphology, histologically and immunohistochemically. The repairs were scored according to the international cartilage repair society (ICRS) standard. RESULTS: The gross morphology results suggested that the defects were repaired completely in the experimental group after twelve weeks. The regenerated tissue connected closely with subchondral bone and the boundary with normal tissue was fuzzy. The cartilage lacuna in the regenerated tissue was similar to normal cartilage lacuna. The results of ICRS gross and histological grading showed that there were significant differences among the three groups (P<0.05). CONCLUSIONS: Chondrocytes implanted in the scaffold can adhere, proliferate, and secrete extracellular matrix. The novel tissue-engineered cartilage constructed in our research can completely repair the structure of damaged articular cartilage.

[Experimental study on tissue engineered cartilage complex three-dimensional nano-scaffold with collagen type II and hyaluronic acid in vitro].

OBJECTIVE: To explore the possibility of constructing tissue engineered cartilage complex three-dimensional nano-scaffold with collagen type II and hyaluronic acid (HA) by electrospinning. METHODS: The three-dimensional porous nano-scaffolds were prepared by electrospinning techniques with collagen type II and HA (8 : 1, W : W), which was dissolved in mixed solvent of 3-trifluoroethanol and water (1 : 1, V : V). The morphology were observed by light microscope and scanning electron microscope (SEM). And the porosity, water absorption rate, contact angle, and degradation rate were detected. Chondrocytes were harvested from 1-week-old Japanese white rabbit, which was disgested by 0.25% trypsin 30 minutes and 1% collagenase overlight. The passage 2 chondrocytes were seeded on the nano-scaffold. The cell adhesion and proliferation were evaluated by cell counting kit 8 (CCK-8). The cell-scaffold composites were cultured for 2 weeks in vitro, and the biological morphology and extracelluar matrix (ECM) secretion were observed by histological analysis. RESULTS: The optimal electrospinning condition of nano-scaffold was 10% electrospinning solution concentration, 10 cm receiver distance, 5 mL/h spinning injection speed. The scaffold had uniform diameter and good porosity through the light microscope and SEM. The diameter was 300-600 nm, and the porosity was 89.5% +/- 25.0%. The contact angle was (35.6 +/- 3.4) degrees, and the water absorption was 1 120% +/- 34% at 24 hours, which indicated excellent hydrophilicity. The degradation rate was 42.24% +/- 1.51% at 48 days. CCK-8 results showed that the adhesive rate of cells with scaffold was 169.14% +/- 11.26% at 12 hours, and the cell survival rate was 126.03% +/- 4.54% at 7 days. The histological and immunohistochemical staining results showed that the chondrocytes could grow well on the scaffold and secreted ECM. And the similar cartilage lacuma structure could be found at 2 weeks after co-culture, which suggested that hyaline cartilage formed. CONCLUSION: The collage type II and HA complex three-dimensional nano-scaffold has good physicochemical properties and excellent biocompatibility, so it can be used as a tissue engineered cartilage