Qianqian Liang

Vascular endothelial growth factor C attenuates joint damage in chronic inflammatory arthritis by accelerating local lymphatic drainage in mice

OBJECTIVE To investigate whether the enhancement of joint lymphangiogenesis by injection of vascular endothelial growth factor C (VEGF-C) adeno-associated virus (AAV) into the affected joints has therapeutic efficacy in chronic inflammatory arthritis in mice. METHODS Tumor necrosis factor-transgenic (TNF-Tg) mice were used as a model of chronic inflammatory arthritis. Human VEGF-C was cloned into an AAV expression vector to generate AAV-VEGF-C. The joints of TNF-Tg mice were injected with AAV-VEGF-C or AAV-luciferase (AAV-Luc) as a control. During the 4 months following injection, magnetic resonance imaging of the joints and lymphatic imaging were performed to assess changes in synovial volume and lymph flow from the joint tissues to local draining lymph nodes. Joint inflammation, bone erosion, and cartilage loss were examined by histologic analyses. Lymphatic vessel formation was assessed using immunohistochemistry. RESULTS Intraarticular administration of AAV-VEGF-C virus significantly attenuated the increase in synovial volume and increased lymphatic vessel number in the joint sections, as compared with that in control AAV-Luc-injected joints, during the 4-month period. This was accompanied by a reduction in the area of inflammation, bone erosion, cartilage loss, and osteoclast numbers. Lymph flow from the joints to local draining lymph nodes was slower in TNF-Tg mice than in wild-type littermates, and was significantly improved with AAV-VEGF-C treatment. CONCLUSION Intraarticular injection of AAV-VEGF-C increased lymphangiogenesis and improved lymphatic drainage from the inflamed joints of mice, resulting in attenuation of joint tissue damage. Thus, improvement of joint lymphatic function by local administration of lymphatic growth factors represents a new therapeutic approach for chronic inflammatory arthritis.

Prolonged upright posture induces degenerative changes in intervertebral discs in rat lumbar spine.

Study Design. Both forelimbs of rats were amputated, and these rats were kept in the custom-made cages that kept the rats in prolonged upright posture. Pathologic changes were observed in the lumbar spine at different time points after the surgery. Objective. To investigate the effect of upright posture on intervertebral discs of rat lumbar spine. Summary of Background Data. Previous studies have shown that increased axial forces on the spine can decrease the height of the intervertebral disc, but there are no data to indicate whether or not long-term and repeated assumption of the upright posture could result in degenerative changes. Methods. The forelimbs of 30 rats were amputated when they were 1-month old. These rats were kept in the custom-made cages and were forced to stand upright on their hind-limbs and tails to obtain water and food. Normal rats of the same ages kept in regular cages were used as control. The rats were killed at 5, 7, and 9 months after the surgery, and the intervertebral discs samples of lumbar spine were harvested for histologic and immunohistochemical studies. Total RNA isolated from these samples was used for real-time PCR of type II collagen (Col2&agr;1), type X collagen (Col10&agr;1), matrix metalloproteinase-13 (MMP-13), aggrecan, and disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5). Results. Histologic analysis showed degenerative changes of the intervertebral discs after surgery such as disordered collagen structure of endplate cartilage, fragmentation of annulus fibrosus, and decreased height of disc. Immunostaining revealed decreased protein level of type II collagen and increased protein expression of type X collagen. Real-time PCR showed upregulated expression of MMP 13, ADAMTS-5, and Col10&agr;1 mRNA and downregulated mRNA expression of Col2&agr;1 and aggrecan. Conclusion. Long-term and repeated assumption of the upright stance accelerates disc degeneration in rats.

A continuous observation of the degenerative process in the intervertebral disc of Smad3 gene knock-out mice.

Study Design. Pathologic changes were observed in the spine of small mother against decapentaplegic (Smad) 3−/− mice at different time points. Objective. To observe the degeneration of the intervertebral disc (IVD) in Smad3 gene knock-out mice with growth. Summary of Background Data. Smad3 gene knock-out (Smad3−/−) mice displays phenotypes similar to human osteoarthritis. Despite the similarities between IVD cartilage endplate and the articular cartilage, there has been relatively little interest in exploring the possibility that IVD degeneration might be driven by the deficiency of Smad3. Methods. The Smad3−/− mice were killed at the 10th, 30th, and 60th day after their birth and the IVD samples of spine were harvested for histologic and immunohistochemical studies. Total RNA isolated from these samples were used for real-time PCR analysis of type II collagen (Col2&agr;1), type X collagen (Col10&agr;1), aggrecan, and transforming growth factor-&bgr;1 (TGF-&bgr;1). Results. Compared with the wild-type mice, Smad3−/− mice appeared significantly smaller in size. Radiograph showed that the spine of Smad3−/− mice is malformation and kyphosis. Histologic analysis revealed the declined height of cartilage endplate, decreased proteoglycan and collagen content in disc of Smad3−/− mice. With growth, especially of the 30- and 60-day old Smad3−/− mice, the protein positive staining of type II collagen, aggrecan, and TGF-&bgr;1 in the disc decreased, while that of type X collagen increased. And the analysis of real-time PCR showed that the mRNA expression of Col2&agr;1, aggrecan, and TGF-&bgr;1 decreased, while that of Col10&agr;1 increased. Conclusion. Smad3 gene knock-out mice develop IVD degeneration with growth.

The ubiquitin E3 ligase WWP1 decreases CXCL12-mediated MDA231 breast cancer cell migration and bone metastasis.

Advanced breast cancers preferentially metastasize to bone where cells in the bone microenvironment produce factors that enhance breast cancer cell homing and growth. Expression of the ubiquitin E3 ligase WWP1 is increased in some breast cancers, but its role in bone metastasis has not been investigated. Here, we studied the effects of WWP1 and itch, its closest family member, on breast cancer bone metastasis. First, we immunostained a multi-tumor tissue microarray and a breast cancer tissue microarray and demonstrated that WWP1 and ITCH are expressed in some of breast cancer cases. We then knocked down WWP1 or itch in MDA-MB-231 breast cancer cells using shRNA and inoculated these cells and control cells into the left ventricle of athymic nude mice. Radiographs showed that mice given shWWP1 cells had more osteolytic lesions than mice given control MDA-MB-231 cells. Histologic analysis confirmed osteolysis and showed significantly increased tumor area in bone marrow of the mice. WWP1 knockdown did not affect cell growth, survival or osteoclastogenic potential, but markedly increased cell migration toward a CXCL12 gradient in vitro. Furthermore, WWP1 knockdown significantly reduced CXCL12-induced CXCR4 lysosomal trafficking and degradation. In contrast, itch knockdown had no effect on MDA-MB-231 cell bone metastasis. Taken together, these findings demonstrate that WWP1 negatively regulates cell migration to CXCL12 by limiting CXCR4 degradation to promote breast cancer metastasis to bone and highlight the potential utility of WWP1 as a prognostic indicator for breast cancer bone metastasis.

Leg amputation accelerates senescence of rat lumbar intervertebral discs.

Study Design. Several senescence biomarkers were observed to investigate cell senescence in degenerative intervertebral lumbar discs of foreleg-amputated rats. Objective. To determine if cell senescence is accelerated in degenerative intervertebral lumbar disc cells in an upright-rat model. Summary of Background Data. Cellular senescence was accelerated in human and sand rat degenerative intervertebral disc (IVD) cells. Repeated use of upright posture by rats contributed to degenerative disc changes. No convincing evidence of cell senescence was observed in the lumbar disc of the foreleg amputated rat. Methods. The forelimbs of 20 rats were amputated at 1 month of age such that they maintained an upright stance; rats were housed in custom-made cages. Nonamputated rats, also 1 month of age, were kept in regular cages and served as a control group. The lumbar IVDs were harvested from rats in 2 groups, at 5 or 9 months following amputation. Senescence-associated-&bgr;-galactosidase-positive staining was used to detect cell senescence. p16INK4a and p27KIP were assessed by immunohistochemistry analysis. Total RNA isolated from these samples was used to measure the gene expression of p16INK4a, RB, cyclin D1, CDK4, PTEN, p27KIP, p19ARF, p21, TERT, and RAGE by real-time polymerase chain reaction assay. Results. The highest levels of SA-&bgr;-GAL activity were detected in 9-month amputated rats. Quantitative immunohistochemical analysis showed that there were highest rates of p16INK4a and p27KIP protein expression in the cartilage endplate and anulus fibrosus of 9-month amputated rats. The mRNA levels of p16INK4a, RB, PTEN, p27KIP, p19ARF, and RAGE were upregulated. The increased cyclin D1 mRNA level was statistically significant only at the ninth month following amputation; CDK4 and TERT mRNA levels were downregulated to a similar extent at both points compared with nonamputated controls. mRNA expression of p21 was significantly downregulated. Conclusion. Accelerated cell senescence was associated with forelimb amputation that causes abnormal loading in rat lumbar IVDs.

The expression of osteoprotegerin is required for maintaining the intervertebral disc endplate of aged mice

OBJECTIVE Human chondrocytes and annulus fibrosus cells of intervertebral disc (IVD) express osteoprotegerin (OPG), but the effect of OPG on the pathogenesis of IVD degeneration remains unknown. Here we assessed the phenotype change of IVD in OPG(-/-) mice. METHODS The IVDs from 12-, 20-, and 28-week-old OPG(-/-) mice and WT controls were subjected to histologic analyses including TRAP staining for osteoclasts, immunostaining for OPG and type I collagen protein expression, and TUNEL staining for apoptosis. The IVD tissues were also subjected to real time RT-PCR for mRNA expression of genes for osteoblast-osterix, ALP, and osteocalcin; for osteoclasts-trap, rank, mmp9 and cathepsin K, and for chondrocytes-aggrecan, mmp13 and Col10. RESULTS OPG protein expresses at the cells of endplate cartilage and annulus fibrosis in IVDs of WT mice. Compared to WT mice, OPG(-/-) mice developed aging related cartilage loss and bony tissue appearance at the endplate. Stating from 20 weeks of age, IVDs from OPG(-/-) mice expressed significantly increased mmp13 and Col10 levels, which is associated with increased osteoblast number and elevated expression of osteoblast marker genes. Furthermore, TRAP+ osteoclasts were presented in the endplate cartilage of OPG(-/-) mice. These osteoclasts localized adjacently to and erosion into the cartilage. Increased expression of RANK, mmp9 and cathepsin k was detected in OPG(-/-) IVDs. CONCLUSIONS OPG at IVD plays an important role for maintaining the integrity of endplate cartilage during aging by preventing endplate cartilage from osteoclast-mediated resorption.

Distribution and alteration of lymphatic vessels in knee joints of normal and osteoarthritic mice.

To investigate the distribution and alteration of lymphatic vessels and draining function in knee joints of normal and osteoarthritic mice.

Over-expression of Sox2 in C3H10T1/2 cells inhibits osteoblast differentiation through Wnt and MAPK signalling pathways.

PurposeMany Sox proteins play important roles both in mesoderm and ectoderm development. It is reported that Sox2, a member of this family, is essential for the maintenance of the self-renewal of embryonic stem cells (ES) and neural stem cells (NSCs). To investigate whether Sox2 participates in mesoderm development besides ectoderm, Sox2 was introduced into C3H10T1/2 cells.MethodsWe produced recombinant retrovirus expressing Sox2 in GP2-293t cells and infected the virus into C3H10T1/2 cells. Growth property, alkaline phosphatase (ALP) staining, mineralized nodules, osteogenic gene expression and related signal pathways were analysed and compared between Sox2-expressing cells and control cells.ResultsSox2 over-expression led to increased proliferation of C3H10T1/2 cells, activation of Wnt/β-catenin and p38MAPK pathways. When cultured in osteogenic differentiation medium, ALP and mineralized nodules formation were inhibited in Sox2 over-expressing cells with down-regulation of osteogenic gene expression as well as inhibition of Wnt/β-catenin and p38MAPK pathways.ConclusionsAll these data suggested that over-expression of Sox2 promoted proliferation and inhibited osteoblast differentiation of C3H10T1/2 cells.

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.

Alteration of lymphatic vessel and function in osteoarthritic joints.

To investigate the distribution and alteration of lymphatic vessels and draining function in knee joints of normal and osteoarthritic mice.