Nanodevices for deep cartilage penetration.

Osteoarthritis (OA) is a degenerative joint disease and is the main cause of chronic pain and functional disability in adults. Articular cartilage is a hydrated soft tissue that is composed of normally quiescent chondrocytes at a low density, a dense network of collagen fibrils with a pore size of 60-200 nm, and aggrecan proteoglycans with high-density negative charge. Although certain drugs, nucleic acids, and proteins have the potential to slow the progression of OA and restore the joints, these treatments have not been clinically applied owing to the lack of an effective delivery system capable of breaking through the cartilage barrier. Recently, the development of nanotechnology for delivery systems renders new ideas and treatment methods viable in overcoming the limited penetration. In this review, we focus on current research on such applications of nanotechnology, including exosomes, protein-based cationic nanocarriers, cationic liposomes/solid lipid nanoparticles, amino acid-based nanocarriers, polyamide derivatives-based nanocarriers, manganese dioxide, and carbon nanotubes. Exosomes are the smallest known nanoscale extracellular vesicles, and they can quickly deliver nucleic acids or proteins to the required depth. Through electrostatic interactions, nanocarriers with appropriate balance in cationic property and particle size have a strong ability to penetrate cartilage. Although substantial preclinical evidence has been obtained, further optimization is necessary for clinical transformation. STATEMENT OF SIGNIFICANCE: The dense cartilage matrix with high-negative charge was associated with reduced therapeutic effect in osteoarthritis patients with deep pathological changes. However, a systematic review in nanodevices for deep cartilage penetration is still lacking. Current approaches to assure penetration of nanosystems into the depth of cartilage were reviewed, including nanoscale extracellular vesicles from different cell lines and nanocarriers with appropriate balance in cationic property and size particle. Moreover, nanodevices entering clinical trials and further optimization were also discussed, providing important guiding significance to future research.

Recent advances in enzyme-related biomaterials for arthritis treatment.

Arthritis is a group of highly prevalent joint disorders, and osteoarthritis (OA) and rheumatoid arthritis are the two most common types. The high prevalence of arthritis causes severe burdens on individuals, society and the economy. Currently, the primary treatment of arthritis is to relieve symptoms, but the development of arthritis cannot be effectively prevented. Studies have revealed that the disrupted balance of enzymes determines the pathological changes in arthritis. In particular, the increased levels of matrix metalloproteinases and the decreased expression of endogenous antioxidant enzymes promote the progression of arthritis. New therapeutic strategies have been developed based on the expression characteristics of these enzymes. Biomaterials have been designed that are responsive when the destructive enzymes MMPs are increased or have the activities of the antioxidant enzymes that play a protective role in arthritis. Here, we summarize recent studies on biomaterials associated with MMPs and antioxidant enzymes involved in the pathological process of arthritis. These enzyme-related biomaterials have been shown to be beneficial for arthritis treatment, but there are still some problems that need to be solved to improve efficacy, especially penetrating the deeper layer of articular cartilage and targeting osteoclasts in subchondral bone. In conclusion, enzyme-related nano-therapy is challenging and promising for arthritis treatment.

Recent Advances in Reactive Oxygen Species (ROS)-Responsive Polyfunctional Nanosystems 3.0 for the Treatment of Osteoarthritis.

Osteoarthritis (OA) is an inflammatory and degenerative joint disease with severe effects on individuals, society, and the economy that affects millions of elderly people around the world. To date, there are no effective treatments for OA; however, there are some treatments that slow or prevent its progression. Polyfunctional nanosystems have many advantages, such as controlled release, targeted therapy and high loading rate, and have been widely used in OA treatment. Previous mechanistic studies have revealed that inflammation and ROS are interrelated, and a large number of studies have demonstrated that ROS play an important role in different types of OA development. In this review article, we summarize third-generation ROS-sensitive nanomaterials that scavenge excessive ROS from chondrocytes and osteoclasts in vivo. We only focus on polymer-based nanoparticles (NPs) and do not review the effects of drug-loaded or heavy metal NPs. Mounting evidence suggests that polyfunctional nanosystems will be a promising therapeutic strategy in OA therapy due to their unique characteristics of being sensitive to changes in the internal environment.

Identification of thrombin as a key regulator of chondrocyte catabolic activity through RNA-Seq and experimental verification.

The present study was designed to explore the relationship between thrombin and catabolic activity in chondrocytes. Primary rat chondrocytes were cultured for 24 h with rat serum (RS), rat plasma (RP), or rat plasma supplemented with thrombin (RPT). RNA-sequencing was then performed. Cell proliferation was analyzed by EdU uptake, CCK-8 assays and protein-protein interaction (PPI) network of proliferation-related genes. Heatmaps were used to visualize differences in gene expression. Gene Ontology (GO) enrichment analyses of up- and down-regulated differentially expressed genes were conducted. Molecular probes were used to label the endoplasmic reticulum in chondrocytes from three treatment groups. Immunofluorescence and Safranin O staining were used to assess type II collagen (Col2a1) expression and proteoglycan synthesis, whereas Lox expression was assessed by immunocytochemistry. The expression of enzymes involved in the synthesis and maturation of extracellular matrix (ECM) components and chemokines were measured by qPCR while matrix metalloproteinases (MMPs) levels were evaluated by Western blotting. Relevant nodules were selected through further PPI network analyses. A total of 727 and 1162 genes were up- and down-regulated based on the Venn diagrams comparison among groups. Thrombin was thus able to promote chondrocyte proliferation and a shift towards fibrotic morphology, while upregulating MMPs and chemokines linked to ECM degradation. In addition, thrombin decreased the enzyme expression involved in the synthesis and maturation of ECM.

A comparative analysis of the osteogenic capacity of osteoblasts from newborn and two-week-old rats.

AIM: To compare the proliferation and osteogenic differentiation of osteoblasts between newborn rats (1d group) and two-week-old rats (14d group) and to clarify the mechanism underlying these effects. METHOD: The endogenous expression of osteogenic marker genes was detected by qPCR, including ALP, OCN, Col1a1, and Runx2. The osteoblasts proliferation was evaluated by EdU assay and Western Blotting [PCNA and Cyclin D1]. ALP activities in osteoblasts were detected using a PNPP kit, ALP staining and qPCR. Mineralized nodule formation and intracellular calcium levels were assessed by Alizarin Red staining and calcium colorimetric assay respectively while OCN, Col1a1 and Runx2 levels in osteoblasts were analyzed by immunostaining. Osteogenesis-associated pathways including Wnt/ß-Catenin, Akt/PPAR and Smad were analyzed via Western Blotting. RESULT: Endogenous ALP, OCN, Col1a1, and Runx2 expression levels were significantly higher in osteoblasts from 14d group than those from 1d group. After treatment with osteogenic induction medium, osteoblast proliferation, ALP activity, mineralized nodule formation, and intracellular calcium levels were markedly increased in osteoblasts from 1d group, with similar results also being observed for the expression of OCN, Col1a1, and Runx2. Wnt3a, ß-catenin, p-Akt, p-Smad1/5/8, and p-Smad5 protein levels were also higher in osteoblasts from 1d group relative to those from 14d group, while the expression of PPARγ was lower. CONCLUSION: The superior osteogenic differentiation capacity in osteoblasts was associated with the higher activation levels of Wnt/ß-Catenin, Akt/PPAR and Smad signaling pathways, and the enhanced proliferative activity in osteoblasts from 1d group.

Similarities and differences between rat and mouse chondrocyte gene expression induced by IL-1ß.

BACKGROUND: Osteoarthritis (OA) is the most prevalent degenerative joint disease. In vitro experiments are an intuitive method used to investigate its early pathogenesis. Chondrocyte inflammation models in rats and mice are often used as in vitro models of OA. However, similarities and differences between them in the early stages of inflammation have not been reported. OBJECTIVE: This paper seeks to compare the chondrocyte phenotype of rats and mice in the early inflammatory state and identify chondrocytes suitable for the study of early OA. METHODS: Under similar conditions, chondrocytes from rats and mice were stimulated using the same IL-1ß concentration for a short period of time. The phenotypic changes of chondrocytes were observed under a microscope. The treated chondrocytes were subjected to RNA-seq to identify similarities and differences in gene expression. Chondrocytes were labelled with EdU for proliferation analysis. Cell proliferation-associated proteins, including minichromosome maintenance 2 (MCM2), minichromosome maintenance 5 (MCM5), Lamin B1, proliferating cell nuclear antigen (PCNA), and Cyclin D1, were analysed by immunocytochemical staining, cell immunofluorescence, and Western blots to verify the RNA-seq results. RESULTS: RNA-seq revealed that the expression patterns of cytokines, chemokines, matrix metalloproteinases, and collagen were similar between the rat and mouse chondrocyte inflammation models. Nonetheless, the expression of proliferation-related genes showed the opposite pattern. The RNA-seq results were further verified by subsequent experiments. The expression levels of MCM2, MCM5, Lamin B1, PCNA, and Cyclin D1 were significantly upregulated in rat chondrocytes (P < 0.05) and mouse chondrocytes (P < 0.05). CONCLUSIONS: Based on the findings, the rat chondrocyte inflammation model may help in the study of the early pathological mechanism of OA.

Intermittent pressure imitating rolling manipulation ameliorates injury in skeletal muscle cells through oxidative stress and lipid metabolism signalling pathways.

BACKGROUND: Traditional Chinese medicine manipulation (TCMM) is often used to treat human skeletal muscle injury, but its mechanism remains unclear due to difficulty standardizing and quantifying manipulation parameters. METHODS: Here, dexamethasone sodium phosphate (DSP) was utilized to induce human skeletal muscle cell (HSkMC) impairments. Cells in a three-dimensional environment were divided into the control normal group (CNG), control injured group (CIG) and rolling manipulation group (RMG). The RMG was exposed to intermittent pressure imitating rolling manipulation (IPIRM) of TCMM via the FX­5000™ compression system. Skeletal muscle damage was assessed via the cell proliferation rate, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and creatine kinase (CK) activity. Isobaric tagging for relative and absolute protein quantification (iTRAQ) and bioinformatic analysis were used to evaluate differentially expressed proteins (DEPs). RESULTS: Higher-pressure IPIRM ameliorated the skeletal muscle cell injury induced by 1.2 mM DSP. Thirteen common DEPs after IPIRM were selected. Key biological processes, molecular functions, cellular components, and pathways were identified as mechanisms underlying the protective effect of TCMM against skeletal muscle damage. Some processes (response to oxidative stress, response to wounding, response to stress and lipid metabolism signalling pathways) were related to skeletal muscle cell injury. Western blotting for 4 DEPs confirmed the reliability of iTRAQ. CONCLUSIONS: Higher-pressure IPIRM downregulated the CD36, Hsp27 and FABP4 proteins in oxidative stress and lipid metabolism pathways, alleviating excessive oxidative stress and lipid metabolism disorder in injured HSkMCs. The techniques used in this study might provide novel insights into the mechanism of TCMM.

MEK1/2 Inhibitor (GDC0623) Promotes Osteogenic Differentiation of Primary Osteoblasts Inhibited by IL-1ß through the MEK-Erk1/2 and Jak/Stat3 Pathways.

OBJECTIVE: We evaluated the effects and mechanisms of GDC0623 on osteogenic differentiation of osteoblasts induced by IL-1ß. Methodology. Osteoblasts were treated with 20 ng/ml IL-1ß and 0.1 µM GDC0623. Cell proliferation levels were evaluated by the cell counting kit 8 (CCK8), EdU assay, and western blotting [proliferating cell nuclear antigen (PCNA) and Cyclin D1]. Osteoblasts were cultured in an osteogenic induction medium for 1-3 weeks after which their differentiations were assessed by alkaline phosphatase (ALP) staining, Alizarin Red staining, calcium concentration, immunocytochemistry staining, real-time quantitative PCR (RT-qPCR), and immunofluorescence staining. The osteogenesis-associated mechanisms were further evaluated by western blotting using appropriate antibodies. RESULTS: Relative to the control group, IL-1ß induced the rapid proliferation of osteoblasts and suppressed their osteogenic differentiations by upregulating the activities of MEK-Erk1/2 as well as Jak-Stat3 pathways and by elevating MMP13 and MMP9 levels. However, blocking of the MEK-Erk1/2 signaling pathway by GDC0623 treatment reversed these effects. CONCLUSION: Inhibition of Jak-Stat3 pathway by C188-9 downregulated the expression levels of MMP9 and MMP13, activated MEK-Erk1/2 pathway, and inhibited osteogenic differentiation.

[Role of TLR4/NF-κB pathway for early change of synovial membrane in knee osteoarthritis rats].

OBJECTIVE: To study role of TLR4/NF-κB pathway for early change of synovial membrane in knee osteoarthritis rats. METHODS: Eighteen male SD rats weighted (200±20) g were randomly divided into 2 groups, namely control and model group, and 9 in each group. Knee OA model group was established by using modified Hulth method in model group. Control group was not treated. Synovial tissue and serum was extracted at 4 and 21 d after operation. Expression of CD14, TLR4, IL-1ß, TNF-α, ADAMTS-4, MMP-13 were detected by real-time PCR respectively. NF-κB p65 protein was detected by Western-blot; serum concentrations of haluronic acid (HA), N-propeptide of type III procollagen(PIIINP) was detected by Elisa. RESULTS: Expression of CD14, ADAMTS-4, and NF-κB p65 in model group were higher than that of control group at 4 and 21 days after operation, while expression of TLR4, IL-1ß, TNF-α and MMP-13 were higher than that of control group at 21 days after operation(P<0.01). Concentration of PIIINP and HA in model group were higher than that of control group at 4 days after operation, while there was no significant difference at 21 days after operation. CONCLUSIONS: NF-κB pathway could mediate occurrence of KOA by early activating and triggeringg synovial increasingly secreting inflammatory secretion CD14, TLR4, IL-1ß, TNF-α, ADAMTS-4, MMP-13, PIIINP and HA.

[Effect of HBP-A on meniscal injury and pathological hypertrophy and calcification of the meniscus].

OBJECTIVE: To investigate the effect of HBP-A on meniscal injuries and the expressions of genes associated with pathological hypertrophy and calcification of the meniscusinduced by abnormal loading. METHODS: Bovine meniscus explants were subjected to 25% strain at 0.3 Hz for 3 h and treated with 0.6 mg/mL of HBP-A. The cell viability in the meniscus explants after 72 hin culture was determined using live/dead staining and the expression levels of genes associated with pathological hypertrophy and calcification of the meniscus (ANKH, ENPP1, ALP, MMP13, and IL-1) were measured using real-time PCR and Western blotting. The conditioned medium was collected for testing sulfated glycosaminoglycan (GAG) release. RESULTS: The number of dead cells, loss of proteoglycan content, and the expressions of ANKH, ENPP1, ALP and MMP13, and IL-1 at both the mRNA and protein levels were all significantly lower in the meniscus explants treated with 0.6 mg/mL HBP-A than in the explants with only 25% abnormal pressure stimulation (n=3, P<0.05). CONCLUSION: HBP-A can effectively alleviate meniscal injuries induced by abnormal loading and suppress the expressions of genes related with pathological hypertrophy and calcification of the meniscus, and can serve as a potential drug for treatment of knee osteoarthritis.

Changes of mesenchymal stromal cells mobilization and bone turnover in an experimental bone fracture model in ovariectomized mice.

OBJECTIVE: The aim of this study was to characterize the mesenchymal stromal cells (MSCs) and endothelial progenitor cells (EPCs) mobilization, and bone turnover in osteoporotic fracture healing in ovariectomized mice. METHODS: In total, 112 female C57/BL mice were divided into two groups. The first group was sham-operated (SO), and the other group was ovariectomized (OVX). After three weeks, the right femora of the mice were fractured under anesthesia and internally fixed with steel pin. Peripheral blood and bone marrow were was collected for flow cytometry analysis, at 0 hours (h), 12 h, 24 h, 72 h and 168 h after fracture. MSCs and EPCs levels were assessed using cell surface antigens in different combinations (CD44+ CD34-CD45-, and CD34+ KDR+CD45-) by flow cytometry. At 0, 14, 28 and 42 days after fracture, sera were assayed for circulating levels of procollagen type I-N-terminal propeptide (P1NP) and C-terminal telopeptide of type I-collagen (CTX) by ELISA. Femurs were harvested at 2 weeks and 6 weeks after fracture for X-ray radiography, micro-computed tomography (micro-CT) and histology. RESULTS: Our results showed that bone marrow and peripheral blood MSCs numbers of the OVX mice were significantly lower than the SO mice, at 12 h, 24 h and 72 h after fracture. In addition, circulating P1NP and CTX levels of the OVX mice were significantly higher than the SO mice, at 2 and 4 weeks. CONCLUSION: Results of the present study revealed disorders of bone marrow MSCs mobilization and bone turnover may partially account for the delay of osteoporotic fracture healing.

[Establishment of chondrocyte degeneration model in vitro by rat serum].

OBJECTIVE: To establish a model of chondrocyte degeneration in vitro. METHODS: Chondrocytes were isolated from articular cartilages of newly born SD rats by digestion with typeⅡ collagenase. The chondrocytes were cultured with H-DMEM medium containing 10%FBS, 50 ng/mL IL-1ß+10%FBS, 2.5% rat serum and 5% rat serum, respectively; and the chondrocytes at passage one were used in the experiments. The morphology changes were investigated under phase contrast microscope after chondrocytes were treated with rat serum and IL-1ß. Proliferation of chondrocytes was detected by MTT method. The protein expression levels of PCNA, typeⅡ collagen and MMP-13 were examined by Western blotting. The levels of ADAMTS5, MMP-9, Aggrecan and SOX-9 mRNA were detected by real-time PCR. RESULTS: The cell morphology was changed from polygon to spindle in both rat serum groups and IL-1ß group, and the proliferation of chondrocytes in these groups was much higher than that in control group. The results showed that the expression levels of typeⅡ collagen, Aggrecan and SOX-9 decreased while the expression levels of MMP-13, MMP-9 and ADMATS5 were up-regulated in rat serum and IL-1ß-treated groups compared with control group. CONCLUSION: The results indicate that rat serum can induce chondrocyte degeneration and may be used for osteoarthritis model in vitro.

[Etablishment of cartilage degeneration model by IL-1 beta in vitro].

OBJECTIVE: To establish a reliable model for drug screening and therapy by culturing rat femoral head and inducing cartilage degeneration quickly in vitro. METHODS: The femoral heads from the same SD rats of two-month old were divided into control group and experimental group respectively. They were cultured with DMEM medium plus 10% fetal bovine serum or DMEM medium plus 10% fetal bovine serum plus 50 ng/ml IL-1ß for three days. Femoral heads were fixed in 4% paraformaldehyde, decalcified, dehydrated, embedded in paraffin and cut into slices. Specimens were stained with Toluidine blue and Safranine O-Fast Green FCF. The protein expression levels of type II collagen, MMP13, Sox9 and ADAMTS5 were analyzed by immunofluorescence. RESULTS: Both the Toluidine blue and Safranine O staining were pale in the margin of femoral heads which were stimulated with IL-1ß for three days compared to that in control group. The Fast Green FCF staining was positive at the edge of the femoral head in experimental group, which indicated that cartilage became degenerated. The expression levels of both type H collagen and Sox9 were decreased significantly while the expression levels of MMP13 and ADAMTS5 were increased in experimental group. CONCLUSION: The model of cartilage degeneration is established by culturing and inducing the degeneration of the femoral heads quickly in vitro.

[Effects of serum enatninine Gumibao (Chinese character: see text) on the aroliferation and differentiation of osteoblast induced by dexamethasone].

OBJECTIVE: To investigate the effects of serum containing Gumibao (Chinese character: see text) on the proliferation and differentiation of osteoblast induced by dexamethasone. METHODS: Osteoblasts were extracted from skulls in newly born (within 24 hours) SD rats, and digested with collagenase. The first passage of cells were used for experiments. Cells were cultured in the medium containing different concentrations of dexamethasone (0, 10(-8), 10(-7), 10(-6), 10(-5) ,10(-4) mol/L). Alkaline phosphatase staining were carried out after 1 week and numbers of mineralized nodes with alizarin red staining were observed after 3 weeks. Accordingly, following the treatment of 10(-5) mol/L dexamethasone for 1 week, cells were cultured in the medium with serum containing Gumibao (Chinese character: see text). One week after Cumibao (Chinese character: see text) treatment, cells were stained with Alkaline phosphatase and collagen I and PCNA were examined by Western-blot. However, the observation of numbers of mineralized nodes with alizarin red stain required one more week. RESULTS: High concentration of dexamethasone could inhibit the expression of PCNA, collagen I, alkaline phosphatase and reduce the number of mineralized nodes of osteoblast, while serum containing Gumibao (Chinese character: see text) could reverse the inhibition. CONCLUSION: High concentration of dexamethasone could inhibit the proliferation and differentiation of osteoblastic cells, while serum containing Gumibao (Chinese character: see text) could reverse the inhibition.

[Regulating effect of anodonta glucan HBP-A on chondrocytes through Wnt pathway].

OBJECTIVE: To investigate regulation function of anodonta glucan HBP-A on chondrocytes through Wnt pathway in vitro. METHODS: Rat chondrocytes were cultured and differentiated induced with IL-1beta (10 ng/ml) in vitro. Chondrocytes were divided into five groups:IL-13 group,IL-1beta + IWP-2 (5 microM,Wnt pathway inhibitor) group, IL-1beta + HBP-A (0.3 mg/ml) group and IL-1beta + IWP-2 + HBP-A group. Wnt-3a, beta-catenin (24 h,48 h,72 h) and MMP-13(72 h) genes expression were detected by Rt-PCR, while beta-catenin, MMP-13, Sox-9 and coll-II (48 h) protein expression were measured by Western-blot. RESULTS: After induction of IL-1beta, gene expression of Wnt-3a, beta-catenin and MMP-13 were increased,so were the protein expression of beta-catenin and MMP-13. In contrast,protein expression of Sox-9 and Coll-II were declined. Following addition of HBP-A, Wnt-3a, beta-catenin and MMP-13 were shown as induction of IL-1beta, but protein expression of Sox-9 and Coll-II were upgraded. Combining HBP-A with IWP-2 led to the lowest level in Wnt-3a, beta-catenin gene and beta-catenin protein expression and highest expression of Sox-9 protein. CONCLUSION: HBP-A could not only delay the differentiation of chondrocytes through downgrading the signal expression of Wnt/beta-catenin,but also adjust the expression of Wnt-3a, beta-catenin and Sox-9 when combinated with the Wnt inhibitor.

Protective effect of ligustrazine on lumbar intervertebral disc degeneration of rats induced by prolonged upright posture.

Most chronic low back pain is the result of degeneration of the lumbar intervertebral disc. Ligustrazine, an alkaloid from Chuanxiong, reportedly is able to relieve pain, suppress inflammation, and treat osteoarthritis and it has the protective effect on cartilage and chondrocytes. Therefore, we asked whether ligustrazine could reduce intervertebral disc degeneration. To determine the effect of ligustrazine on disc degeneration, we applied a rat model. The intervertebral disc degeneration of the rats was induced by prolonged upright posture. We found that pretreatment with ligustrazine for 1 month recovered the structural distortion of the degenerative disc; inhibited the expression of type X collagen, matrix metalloproteinase (MMP)-13, and MMP3; upregulated type II collagen; and decreased IL-1 ß , cyclooxygenase (COX)-2, and inducible nitric oxide synthase (iNOS) expression. In conclusion, ligustrazine is a promising agent for treating lumbar intervertebral disc degeneration disease.

Mechanism of resveratrol on the promotion of induced pluripotent stem cells.

OBJECTIVE: To investigate the effects of resveratrol (RV) in reprogramming mouse embryonic fibroblasts (MEFs) into induced pluripotent stem cells (iPSCs) and the related mechanism. METHODS: Primary MEFs were isolated from E13.5 embryos and used within three passages. Retroviruses expressing Sox2 and Oct4 were produced by transfecting GP2-293t cells with recombinant plasmids (MSCV)-Sox2 and MSCV-Oct4. Supernatants containing retroviruses were obtained after 48-hour transfection and MEFs were then infected. Different concentrations (0, 5, 10 and 20 µmol/L) of RV were added to embryonic stem cell (ESC) medium to culture MEFs 48 h post-infection. iPSC clones emerged and were further cultured. Expression of pluripotent markers of iPSCs was identified by cell immunofluorescence and reverse transcription-polymerase chain reaction. Both cytotoxicity and cell proliferation were assayed by Western blot analysis after RV was added into ESC medium. The ultrastructure change of mitochondria was observed by electron microscopy. RESULTS: More than 2.9-fold and 1.3-fold increases in colony number were observed by treatment with RV at 5 and 10 µmol/L, respectively. The reprogramming efficiency was significantly decreased by treatment with 20 µmol/L RV. The proliferation effect on MEFs or MEFs infected by two factors Sox2/Oct4 (2 factors-MEFs, 2F-MEFs) was investigated after RV treatment. At 20 µmol/L RV, induced cell apoptosis and proliferation inhibition were more obvious than those of 5 and 10 µmol/L treatments. Clones were selected from the 10 µmol/L RV-treated group and cultured. Green fluorescent protein expression from one typical clone was silenced one month later which expressed ESC-associated marker genes Gdf3, Nanog, Ecat1, Fgf4 and Foxd3. Electron transmission microscope showed obvious cavitations in mitochondria. The expression of hypoxia-inducible factor-1α was up-regulated when 2F-MEFs were treated with RV compared to the control group. CONCLUSION: RV improved the efficiency of reprogramming 2F-MEFs into iPSCs at low and moderate concentrations (5 and 10 µmol/L). The effect of 10 µmol/L RV on reprogramming was much greater than that of 5 µmol/L RV. However, high concentration of RV (20 µmol/L) led to more severe cavitations in mitochondria and caused cytotoxic effects. Taken together, these findings suggest that RV mimics hypoxia in cells and promotes reprogramming at a low concentration.

[Effect of osthole on proliferation of neonatal rat osteoblast and the relative mechanism research].

OBJECTIVE: To investigate the effects of osthole on proliferation of neonatal rat osteoblast and the mechanism. METHODS: Ten 24 hours old SD rats were executed by dislocating. The cranium of rats were removed and cut into blocks of 1 mm x 1 mm size. After digested by trypsin for 15 min, the cranium were digested by type I collagenase for one hour two times. The mixed cells were cultured in thermostat incubator with 5% CO2 under the condition of 37 degrees C. To identify the cells, ALP staining and alizarin red staining were performed after cultured 48 h and 28 d. The osteoblasts were randomly divided into five groups. Cells were treated with osthole at concentrations of 100, 50, 25, 12.5, 0 micromol/L. CCK-8 method was used to evaluate the proliferation after 24 h,48 h and 72 h. The expression of PCNA and beta-catenin protein were detected through the method of Western Blot after one week. RESULTS: The cells had irregular shapes and showed typical features of osteoblast. The results of ALP staining and alizarin red staining were both positive. CCK-8 detection showed that the osthole with final concentration of 100 micromol/L inhibited the proliferation of osteoblast after 24 h, while the osthole with final concentrations of 50 micromol/L and 25 micromol/L displayed the inhibition effect after 48 h. The osthole of 12.5 micromol/L had no obvious influence on the proliferation of osteoblast. The result of Western Blot showed that osthole reduced the expression of PCNA and beta-catenin protein in a dose-dependent manner. CONCLUSION: The osthole with final concentrations of 100, 50, 25 micromol/L inhibited the proliferation of osteoblast (P < 0.05). The osthole with final concentrations of 12.5 micromol/L had no obvious influence on the proliferation of osteoblast (P > 0.05). These findings demonstrate that osthole may inhibit the proliferation of osteoblast by regulating the Wnt/beta-catenin signaling in osteoblast.

[Comparison of the activity and yield rate of osteoblast obtained by different digestion methods].

OBJECTIVE: To compared the activity and yield rate of osteoblast obtained by different collagenase digestion methods, to find a better way to extract osteoblast for the experimental researches of osteoporosis. METHODS: Ten 24-hour-old SD rats were were euthanized. The cranium of rats were removed and cuted into blocks of 1 mm x 1 mm size. After digested by trypsin for 15 min, all the cranium were divided into two equal parts, and randomly divided into two groups which would be digested by type I collagenase and type II collagenase separately for two times. The rat cells of the two groups were cultured in thermostat incubator with 5% CO2 under the condition of 37 degrees C. The primary culture osteoblasts were counted by using a haemacytometer after digestion and 72 hours later. The second generation osteoblasts cultured 48 h were dyed by NBT/BCIP staining solution, and were detected by quantitative measurement with PNPP. RESULTS: The cells had irregular shapes. The results of cell counting showed that the cell number of type I group was larger than type 11 group. Alkaline phosphatase dyeing were positive. Detecting of alkaline phosphatase using the method of PNPP showed that the absorbance value in type I group were higher than type II group (P<0.05). CONCLUSION: Two types of collagenase are both suitable for the in vitro culture of rat osteoblasts. The activity and yield rate of osteoblasts in type I group are higher which could provide more stable seed cells for the treatment of osteoporosis.

[Inhibition effect of osthole on proliferation of rat chondrocytes].

OBJECTIVE: To investigate the effects of osthole on chondrocyte proliferation in vitro. METHODS: Primary rat chondrocytes were isolated from the femoral head of newborn rats using collagenase digestion and cultured in Dulbecco's modified Eagle's medium. The proliferation of primary chondrocytes was assessed in second-passage cultures using cell counting kit-8 and the growth curve was drawn. Type II procollagen gene (Col2a1) expression in chondrocytes was also identified using cell immunofluorescence assay. The second-passage chondrocytes were divided into five groups, including control group and osthole groups at 6.25, 12.5, 25 and 50 µmol/L. The growth property of rat chondrocytes was observed after 24, 48 and 72 h of culture with osthole at corresponding dose. Both protein and mRNA expression of proliferating cell nuclear antigen (PCNA) and cyclin D1 was measured by Western blot and polymerase chain reaction methods. RESULTS: The second-passage chondrocytes were viable and showed Col2a1 expression in the cytoplasm. The proliferation of rat chondrocytes was inhibited by osthole in a dose-dependent manner. Meanwhile, there were significant decreases in both protein and mRNA expression of PCNA and cyclin D1 in the osthole groups compared with the control group. CONCLUSION: Osthole exhibits inhibitory effect on proliferation of rat chondrocytes by down-regulating PCNA and cyclin D1 expression.