Graphene and its derivatives have unique physical,chemical and biological properties,such as antibacterial property,promoting osteogenesis,increasing the wear resistance of composite materials,etc.It has broad application prospects in biomedicine and tissue engineering.The application and research progress of graphene and its derivatives in orthopedics were introduced,in order to provide theoretical basis for the future clinical and fundamental research.

Background::Previous studies have reported that mitochondrial dysfunction participates in the pathological process of osteoarthritis (OA). However, studies that improve mitochondrial function are rare in OA. Mitochondrial transfer from mesenchymal stem cells (MSCs) to OA chondrocytes might be a cell-based therapy for the improvement of mitochondrial function to prevent cartilage degeneration. This study aimed to determine whether MSCs can donate mitochondria and protect the mitochondrial function and therefore reduce cartilage degeneration.Methods::Bone-marrow-derived mesenchymal stromal cells (BM-MSCs) were harvested from the marrow cavities of femurs and tibia in young rats. OA chondrocytes were gathered from the femoral and tibial plateau in old OA model rats. BM-MSCs and OA chondrocytes were co-cultured and mitochondrial transfer from BM-MSCs to chondrocytes was identified. Chondrocytes with mitochondria transferred from BM-MSCs were selected by fluorescence-activated cell sorting. Mitochondrial function of these cells, including mitochondrial membrane potential (Δψm), the activity of mitochondrial respiratory chain (MRC) enzymes, and adenosine triphosphate (ATP) content were quantified and compared to OA chondrocytes without mitochondrial transfer. Chondrocytes proliferation, apoptosis, and secretion ability were also analyzed between the two groups.Results::Mitochondrial transfer was found from BM-MSCs to OA chondrocytes. Chondrocytes with mitochondrial from MSCs (MSCs + OA group) showed increased mitochondrial membrane potential compared with OA chondrocytes without mitochondria transfer (OA group) (1.79 ± 0.19 vs. 0.71 ± 0.12, t = 10.42, P < 0.0001). The activity of MRC enzymes, including MRC complex I, II, III, and citrate synthase was also improved ( P < 0.05). The content of ATP in MSCs + OA group was significantly higher than that in OA group (161.90 ± 13.49 vs. 87.62 ± 11.07 nmol/mg, t = 8.515, P < 0.0001). Meanwhile, we observed decreased cell apoptosis (7.09% ± 0.68% vs.15.89% ± 1.30%, t = 13.39, P < 0.0001) and increased relative secretion of type II collagen (2.01 ± 0.14 vs.1.06 ± 0.11, t = 9.141, P = 0.0008) and proteoglycan protein (2.08 ± 0.20 vs. 0.97 ± 0.12, t = 8.227, P = 0.0012) in MSCs + OA group, contrasted with OA group. Conclusions::Mitochondrial transfer from BM-MSCs provided protection for OA chondrocytes against mitochondrial dysfunction and degeneration through improving mitochondrial function, cell proliferation, and inhibiting apoptosis in chondrocytes. This finding may offer a new therapeutic direction for OA.

Objective:To investigate whether endogenous hydrogen sulfide (H2 S)was involved in the pathogenesis of osteoarthritis (OA)and its underlying mechanism,to detect H2 S and its synthases ex-pression in knee cartilage in patients diagnosed with different severity of OA,and to explore the transcrip-tion and expression of gene MMP-13 in chondrocytes treated with IL-1βor H2S.Methods:Synovial fluids of the in-patients with different severity of OA hospitalized in Peking University First Hospital were collected for measurement of H2 S content using methylene blue assay.Articular cartilages of the patients who underwent knee arthroplasty were collected for the cell culture of relatively normal chondrocytes.The chondrocytes were cultured to the P3 generation and H2 S molecular probes were used for detection of endogenous H2 S generation in the chondrocytes.Immunocytochemistry was used to detect the localization of H2 S synthases including cystathionine β-synthase (CBS),cystathionine-γ-lyase (CSE),and mercap-topyruvate sulfurtransferase (MPST)in OA chondrocytes.Western blot was used to quantify the protein expressions of CSE,MPST,and CBS in cartilage tissues of the patients who were diagnosed with OA and underwent knee arthroplasty.The relatively normal human chondrocytes were cultured to passage 3 and then divided into 4 groups for different treatments:(1 )the normal control group,no reagent was added;(2)the IL-1βgroup,5 μg/L of IL-1βwas added;(3)the IL-1β+H2S group,200 μmol/L of NaHS was added 30 min before adding 5 μg/L of IL-1β;(4)the H2 S group,200 μmol/L of NaHS was added. The transcription and expression of gene MMP-13 in chondrocytes of each group were determined with Real-time PCR and Western blot,respectively.And the total NF-κB p65 and phosphorylated NF-κB p65 in chondrocytes were detected with Western blot.Results:The content of H2 S in the synovial fluid of degenerative knee was (14.3 ±3.3)μmol/L.Expressions of endogenous H2 S and its synthases including CBS,CSE and MPST were present in the cytoplasm of chondrocytes.CSE protein expression in Grade 3 (defined by outerbridge grading)cartilage tissues was significantly increased as compared with that of Grade 1 cartilage tissues (1.67 ±0.09 vs.1.26 ±0.11,P<0.05).However,no significant difference of CBS or MPST expression among the different groups was observed.The expression of MMP-13 protein in the IL-1βgroup was significantly higher than that in the normal chondrocytes (1 .87 ±0.67 vs.0.22 ± 0.10,P<0.05 ),and that in the IL-1β+H2 S group was significantly decreased than that in the IL-1βgroup (0.55 ±0.11 vs.1.87 ±0.67,P<0.05),and that in the H2S group had no significant difference compared with that in the normal control group.The transcription of MMP-13 protein in the IL-1βgroup was significantly higher than that in the normal chondrocytes (31.40 ±0.31 vs.1.00 ±0.00,P<0.05), and that in the IL-1β+H2 S group was significantly decreased than that in the IL-1βgroup (24.41 ± 1.28 vs.31.40 ±0.31,P<0.05),and that in the H2S group had no significant difference compared with that in the normal control group.The total NF-κB p65 in the IL-1βgroup was significantly higher than that in the normal chondrocytes (2.13 ±0.08 vs.0.73 ±0.08,P<0.05),and that in the IL-1β+H2S group was significantly decreased than that in the IL-1βgroup (1 .24 ±0.13 vs.2.13 ±0.08,P<0.05 ),and that in the H2 S group had no significant difference compared with that in the normal control group.The phosphorylated NF-κB p65 in IL-1βgroup was significantly higher than that in the normal chondrocytes (1.30 ±0.13 vs.0.19 ±0.04,P<0.05),and that in IL-1β+H2S group was significantly decreased than that in the IL-1βgroup (0.92 ±0.26 vs.1.30 ±0.13,P<0.05),and that in the H2S group had no significant difference compared with that in the normal control group.Conclusion:H2 S affected the cartilage degeneration by partly inhibiting the degradation of extracellular matrix.

Background: Plant homeodomain finger protein 23 (PHF23) is a novel autophagy inhibitor gene that has been few studied with respect to orthopedics. This study was to investigate the expression of PHF23 in articular cartilage and synovial tissue, and analyze the relationship between PHF23 and chondrocyte autophagy in osteoarthritis (OA). Methods: Immunohistochemical staining and western blot were applied to show the expression of PHF23 in cartilage of different outbridge grades and synovial tissue of patient with OA and healthy control. The normal human chondrocyte pre-treated with rapamycin or 3-methyladenine, treated with interleukin-1β (IL-1β). IL-1β induced expression level of PHF23 and autophagyrelated proteins light chain 3B-I (LC3B-I), LC3B-II, and P62, were examined by Western blot. A PHF23 gene knock-down model was constructed with small interfering RNA. Western blot was performed to detect the efficiency of PHF23 and the impact of PHF23 knockout on IL-1β-induced expression of autophagy-related and apoptotic-related proteins in chondrocyte. Results: The expression of PHF23 was significantly increased in the high-grade cartilage and synovial tissue of patients with OA. The IL-1β-induced expression of PHF23 was gradually enhanced with time. The level of LC3B-II, P62 changed with time. After knockdown of PHF23, the level of autophagy-related proteins increased and apoptotic-related proteins decreased in IL-1β-induced OA-like chondrocytes. Conclusions The expression of PHF23 increased in human OA cartilage and synovium, and was induced by IL-1β through inflammatory stress. PHF23 can suppress autophagy of chondrocytes, and accelerate apoptosis.