Fengjing Guo

miR‑142‑3p promotes osteoblast differentiation by modulating Wnt signaling

Canonical Wnt signaling is critical for the control of osteoblast differentiation in human mesenchymal stem cells. MicroRNAs (miRs) are essential regulators of cell differentiation by post‑transcriptional regulation of target gene expression. The aim of the present study was to investigate the molecular mechanism by which miR‑142‑3p promotes osteoblastic differentiation using the human fetal osteoblastic 1.19 (hFOB1.19), real-time PCR and western blot analysis. Results showed an increased expression of miR‑142‑3p during osteoblast differentiation in the mesenchymal precursor cell line, hFOB1.19. In addition, the ectopic over-expression of miR‑142‑3p promoted hFOB1.19 differentiation, whereas the inhibition of miR‑142‑3p repressed differentiation. The expression of miR‑142‑3p was positively correlated with β‑catenin, an important protein in Wnt signaling. The adenomatous polyposis coli (APC) gene was a direct target of miR‑142‑3p, whereby miR‑142‑3p promoted Wnt signaling through inhibition of APC, leading to accumulation and nuclear translocation of β‑catenin. Therefore, miR‑142‑3p may be an essential mediator of osteoblast differentiation and a new therapeutic strategy for osteogenesis disorders.

A short-hairpin RNA targeting osteopontin downregulates MMP-2 and MMP-9 expressions in prostate cancer PC-3 cells.

Osteopontin (OPN), a secreted phosphoglycoprotein, is frequently associated with cell proliferation and tumor metastatic spread in a variety of cancers. It has been reported that OPN induce matrix metalloproteinase (MMP)-2 and MMP-9 activations through nuclear factor kappaB (NF-kappaB)-mediated signaling pathways. In this study, we investigated the roles of OPN in human prostate cancer cells and provided clues about the possible functions of IkappaB kinase (IKK) in NF-kappaB-mediated OPN-induced activations of MMP-2 and MMP-9. Short-hairpin RNA (shRNA) expression vectors were used to inhibit OPN expression in PC-3 cells, human prostate cancer cell line, and IKK inhibitor VII were applied to inhibit the activities of IKK-1 and IKK-2. The results showed that OPN shRNA-mediated RNA interference can downregulate OPN, MMP-2 and MMP-9 expressions, thereby resulting in suppression of the proliferation, migration and invasion of PC-3 cells in vitro and tumor growth in vivo. Moreover, the inhibition of IKK-2 can suppress MMP-2 and MMP-9 expressions, in contrast, the inhibition of IKK-1 has no effects on the OPN, MMP-2 and MMP-9 expression levels. Thus, this study demonstrated that OPN knockdown could downregulate MMP-2 and MMP-9 expressions result in inhibiting the malignant physiological behaviors of PC-3 cell and that IKK-2 may play a crucial role in OPN-induced MMP-2 and MMP-9 expressions via NF-kappaB-mediated signaling pathways.

LY294002 induces G0/G1 cell cycle arrest and apoptosis of cancer stem-like cells from human osteosarcoma via down-regulation of PI3K activity.

Osteosarcoma, the most common primary mesenchymal malignant tumor, usually has bad prognosis in man, with cancer stem-like cells (CSCs) considered to play a critical role in tumorigenesis and drug-resistance. It is known that phosphatidylinositol 3-kinase (PI3K) is involved in regulation of tumor cell fates, such as proliferation, cell cycling, survival and apoptosis. Whether and how PI3K and inhibitors might cooperate in human osteosarcoma CSCs is still unknown. We therefore evaluated the effects of LY294002, a PI3K inhibitor, on the cell cycle and apoptosis of osteosarcoma CSCs in vitro. LY294002 prevented phosphorylation of protein kinase B (PKB/Akt) by inhibition of PI3K phosphorylation activity, thereby inducing G0/G1 cell cycle arrest and apoptosis in osteosarcoma CSCs. Further studies also demonstrated that apoptosis induction by LY294002 is accompanied by activation of caspase-9, caspase-3 and PARP, which are involved in the mitochondrial apoptosis pathway. Therefore, our results indicate PI3K inhibitors may represent a potential strategy for managing human osteosarcoma via affecting CSCs.

Inhibitory effects of high glucose/insulin environment on osteoclast formation and resorption in vitro

Patients with type 2 diabetes mellitus (T2DM) exhibit hyperglycemia and hyperinsulinemia and increased risk of fracture at early stage, but they were found to have normal or even enhanced bone mineral density (BMD). This study was aimed to examine the molecular mechanisms governing changes in bone structure and integrity under both hyperglycemic and hyperinsulinemic conditions. Monocytes were isolated from the bone marrow of the C57BL/6 mice, induced to differentiate into osteoclasts by receptor activator of nuclear factor kappa-B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) and exposed to high glucose (33.6 mmol/L), high insulin (1 μmol/L), or a combination of high glucose/high insulin (33.6 mmol/L glucose and 1 μmol/L insulin). Cells cultured in α-MEM alone served as control. After four days of incubation, the cells were harvested and stained for tartrate resistant acid phosphatase (TRAP). Osteoclast-related genes including RANK, cathepsin K and TRAP were determined by using real-time PCR. The resorptive activity of osteoclasts was measured by using a pit formation assay. Osteoclasts that were derived from monocytes were of multinucleated nature and positive for TRAP, a characteristic marker of osteoclasts. Cell counting showed that the number of osteoclasts was much less in high glucose and high glucose/high insulin groups than in normal glucose and high insulin groups. The expression levels of RANK and cathepsin K were significantly decreased in high glucose, high insulin and high glucose/high insulin groups as compared with normal glucose group, and the TRAP activity was substantially inhibited in high glucose environment. The pit formation assay revealed that the resorptive activity of osteoclasts was obviously decreased in high glucose group and high glucose/high insulin group as compared with normal group. It was concluded that osteoclastogenesis is suppressed under hyperglycemic and hyperinsulinemic conditions, suggesting a disruption of the bone metabolism in diabetic patients.SummaryPatients with type 2 diabetes mellitus (T2DM) exhibit hyperglycemia and hyperinsulinemia and increased risk of fracture at early stage, but they were found to have normal or even enhanced bone mineral density (BMD). This study was aimed to examine the molecular mechanisms governing changes in bone structure and integrity under both hyperglycemic and hyperinsulinemic conditions. Monocytes were isolated from the bone marrow of the C57BL/6 mice, induced to differentiate into osteoclasts by receptor activator of nuclear factor kappa-B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) and exposed to high glucose (33.6 mmol/L), high insulin (1 μmol/L), or a combination of high glucose/high insulin (33.6 mmol/L glucose and 1 μmol/L insulin). Cells cultured in α-MEM alone served as control. After four days of incubation, the cells were harvested and stained for tartrate resistant acid phosphatase (TRAP). Osteoclast-related genes including RANK, cathepsin K and TRAP were determined by using real-time PCR. The resorptive activity of osteoclasts was measured by using a pit formation assay. Osteoclasts that were derived from monocytes were of multinucleated nature and positive for TRAP, a characteristic marker of osteoclasts. Cell counting showed that the number of osteoclasts was much less in high glucose and high glucose/high insulin groups than in normal glucose and high insulin groups. The expression levels of RANK and cathepsin K were significantly decreased in high glucose, high insulin and high glucose/high insulin groups as compared with normal glucose group, and the TRAP activity was substantially inhibited in high glucose environment. The pit formation assay revealed that the resorptive activity of osteoclasts was obviously decreased in high glucose group and high glucose/high insulin group as compared with normal group. It was concluded that osteoclastogenesis is suppressed under hyperglycemic and hyperinsulinemic conditions, suggesting a disruption of the bone metabolism in diabetic patients.

Effects of non-surgical factors on digital replantation survival rate: a meta-analysis

This study aimed to evaluate the risk factors affecting survival rate of digital replantation by a meta-analysis. A computer retrieval of MEDLINE, OVID, EMBASE, and CNKI databases was conducted to identify citations for digital replantation with digit or finger or thumb or digital or fingertip and replantation as keywords. RevMan 5.2 software was used to calculate the pooled odds ratios. In total, there were 4678 amputated digits in 2641 patients. Gender and ischemia time had no significant influence on the survival rate of amputation replantation (P > 0.05). Age, injured hand, injury type, zone, and the method of preservation the amputated digit significantly influence the survival rate of digital replantation (P < 0.05). Children, right hand, crush, or avulsion and little finger are the risk factors that adversely affect the outcome. The level of evidence: Level 5*.

Neurogenic Differentiation of Murine Adipose Derived Stem Cells Transfected with EGFP in vitro

SummarySome studies indicate that adipose derived stem cells (ADSCs) can differentiate into adipogenic, chondrogenic, myogenic, and osteogenic cells in vitro. However, whether ADSCs can be induced to differentiate into neural cells in vitro has not been clearly demonstrated. In this study, the ADSCs isolated from the murine adipose tissue were cultured and transfected with the EGFP gene, and then the cells were induced for neural differentiation. The morphology of those ADSCs began to change within two days which developed into characteristics of round cell bodies with several branching extensions, concomitantly expressing EGFP fluorescence. Approximately 60% of the total cell populations were bipolar or multipolar in shape. Some of them appeared to make contact with their neighboring cells. RT-PCR, Western blot and Immunocytochemistry revealed that the expression levels of the markers of neurons and oligodendrocytes such as MAP2, NF-70, Neu N and RIP upon neural induction were increased, but the expression of the special marker of astrocytes, GFAP, was undetectable until 96 h after induction when a small signal was observed. It was concluded that the ADSCs transfected with EGFP possessed the ability to undergo morphologic and phenotypic changes consistent with neural differentiation in vitro. It suggests that these cells might provide an ideal source for further stem cell research with possible therapeutic application for spinal cord injury.Some studies indicate that adipose derived stem cells (ADSCs) can differentiate into adipogenic, chondrogenic, myogenic, and osteogenic cells in vitro. However, whether ADSCs can be induced to differentiate into neural cells in vitro has not been clearly demonstrated. In this study, the ADSCs isolated from the murine adipose tissue were cultured and transfected with the EGFP gene, and then the cells were induced for neural differentiation. The morphology of those ADSCs began to change within two days which developed into characteristics of round cell bodies with several branching extensions, concomitantly expressing EGFP fluorescence. Approximately 60% of the total cell populations were bipolar or multipolar in shape. Some of them appeared to make contact with their neighboring cells. RT-PCR, Western blot and Immunocytochemistry revealed that the expression levels of the markers of neurons and oligodendrocytes such as MAP2, NF-70, Neu N and RIP upon neural induction were increased, but the expression of the special marker of astrocytes, GFAP, was undetectable until 96 h after induction when a small signal was observed. It was concluded that the ADSCs transfected with EGFP possessed the ability to undergo morphologic and phenotypic changes consistent with neural differentiation in vitro. It suggests that these cells might provide an ideal source for further stem cell research with possible therapeutic application for spinal cord injury.

Glycosaminoglycan chains of biglycan promote bone morphogenetic protein-4-induced osteoblast differentiation

Biglycan (BGN) has been reported to promote bone morphogenetic protein-4 (BMP-4) stimulated osteoblastic differentiation. However, the underlying mechanism has yet to be fully elucidated. The glycosaminoglycan (GAG) chains of BGN have a variety of biological functions. In the present study, we explored the potential role of the GAG chains of BGN in promoting BMP-4-induced osteoblast differentiation. BGN knockout (KO) murine calvarial cells were transfected with adenovirus overexpressing wild-type BGN (Adv-BGN), adenovirus expressing GAG-mutant BGN (Adv-BGNm) and adenovirus without BGN (Adv-Emp). Transfected cells were treated with or without BMP-4. Subsequently, BMP-4 signaling and function were assessed by evaluating the expression of the osteoblast differentiation-related proteins, Smad1/5/8 phosphorylation and alkaline phosphatase (ALP) activity. Furthermore, the binding specificity of the transfected cells to BMP-4 was also investigated using immunofluorescence staining. Our study demonstrated that a mutant BGN lacking GAG chains decreased BGN-assisted BMP-4 signaling and osteoblast differentiation and that the expression of this mutant BGN in biglycan knockout (BGN‑KO) calvarial osteoblasts could not rescue its differentiation deficiency as efficiently as wild-type (WT) BGN. These results strongly suggest that the GAG chains of BGN promote BGN-assisted BMP-4 function.

Regulation of PTHrP expression by cyclic mechanical strain in postnatal growth plate chondrocytes

Mechanical loading has been widely considered to be a crucial regulatory factor for growth plate development, but the exact mechanisms of this regulation are still not completely understood. In the growth plate, parathyroid hormone-related protein (PTHrP) regulates chondrocyte differentiation and longitudinal growth. Cyclic mechanical strain has been demonstrated to influence growth plate chondrocyte differentiation and metabolism, whereas the relationship between cyclic mechanical strain and PTHrP expression is not clear. The objective of this study was to investigate whether short-term cyclic tensile strain regulates PTHrP expression in postnatal growth plate chondrocytes in vitro and to explore whether the organization of cytoskeletal F-actin microfilaments is involved in this process. To this end, we obtained growth plate chondrocytes from 2-week-old Sprague-Dawley rats and sorted prehypertrophic and hypertrophic chondrocytes using immunomagnetic beads coated with anti-CD200 antibody. The sorted chondrocytes were subjected to cyclic tensile strain of varying magnitude and duration at a frequency of 0.5 Hz. We found that cyclic strain regulates PTHrP expression in a magnitude- and time-dependent manner. Incubation of chondrocytes with cytochalasin D, an actin microfilament-disrupting reagent, blocked the induction of PTHrP expression in response to strain. The results suggest that short-term cyclic tensile strain induces PTHrP expression in postnatal growth plate prehypertrophic and hypertrophic chondrocytes and that PTHrP expression by these chondrocytes may subsequently affect growth plate development. The results also support the idea that the organization of cytoskeletal F-actin microfilaments plays an important role in mechanotransduction.

Bone morphogenetic proteins induce rabbit bone marrow-derived mesenchyme stem cells to differentiate into osteoblasts via BMP signals pathway.

Abstract Bone marrow mesenchymal stem cells (BMMSCs) are multipotent stem cells that can differentiate into different blastoderm cells in vitro. In this study, BMMSCs in rabbit bone marrow were isolated by density gradient centrifuge separation, purified and expanded in vitro. BMP-2 and FGF 2 were used for differentiation into osteoblasts, and the results demonstrated that bone morphogenetic proteins (BMPs) could affect the differential direction of the BMMSCs. PCR assays indicated that BMP signals pathway played important roles in osteoblasts differentiation of BMMSCs, and the members included BMPRI, Smad 1, Smad 5, Smad 8, Runx 2, collage type I and osteopontin. This study provides a theoretical basis and experimental evidence for the therapeutic application of BMMSCs to the treatment of bone injury.

Decreased osteoclastogenesis, osteoblastogenesis and low bone mass in a mouse model of type 2 diabetes

The effect of type 2 diabetes mellitus (T2DM) on bone is controversial. Therefore, the present study investigated whether T2DM causes osteoporosis and explored the underlying mechanisms involved in this process. The effects of T2DM on bone physiology were analyzed in a mouse model of T2DM; KK/Upj‑Ay/J (KK‑Ay) mice develop diabetes after 8 weeks and exhibit stable diabetes symptoms and signs after 10 weeks when fed a KK‑Ay mouse maintenance fodder. Diabetic mice exhibited hyperglycemia, hyperinsulinemia and increased body and fat pad weight in comparison with C57BL/6 non-diabetic mice. Furthermore, diabetic mice demonstrated low bone weight and bone mineral density in the femur, tibia and fifth lumbar vertebra. Using von Kossa and tartrate-resistant acid phosphatase (TRAP) staining, alkaline phosphatase and TRAP activity analyses and gene profiling it was demonstrated that osteoblastogenesis and osteoclastogenesis were impaired in diabetic mice. To evaluate the bone biomechanics, the ultimate load of the bone was analyzed. It was found that the ultimate load of the tibia in diabetic mice was lower than that in the controls. The results from the present study suggest that bone metabolism is impaired in T2DM, resulting in decreased osteoblastogenesis, osteoclastogenesis and bone mass.