Bmp2 gene in osteoblasts of periosteum and trabecular bone links bone formation to vascularization and mesenchymal stem cells

Authors

W. Yang, D. Guo, M.A. Harris, Y. Cui, J. Gluhak-Heinrich, J. Wu, X.-D. Chen, C Skinner, J. Nyman, J.R. Edwards, G.R. Mundy, A. Lichtler, B. Kream, D. Rowe, I. Kalajzic, V. David, D. Quarles, D. Villareal, Greg Scott, Manas Ray, S. Liu, J.F. Martin, Y. Mishina and S.E. Harris

Abstract

We generated a new Bmp2 conditional knock-out allele without a neo cassette and removed Bmp2 gene in osteoblasts (Bmp2-cKOob) using the 3.6Col1a1-Cre transgenic model. Bones of Bmp2-cKOob mice are thinner, with increased brittleness. Osteoblast activity is reduced as reflected in reduced bone formation rate, and failure to differentiate to a mature mineralizing stage. Bmp2 in osteoblasts also indirectly controls angiogenesis in the periosteum and bone marrow. VegfA production is reduced in Bmp2-cKOob osteoblasts. Deletion of Bmp2 in osteoblasts also leads to defective mesenchymal stem cells (MSC), which correlates with the reduced microvascular bed in the periosteum and trabecular bones. Several marker genes of MSC (α-SMA, CD146 and Angiopoietin-1), in vitro CFU assays and deletion of the Bmp2 gene in vitro in α-SMA+ BMSC support our conclusions. Critical roles of the Bmp2 gene in osteoblasts and MSC are a vital link between bone formation, vascularization and mesenchymal stem cells.

Link to Article

http://dx.doi.org/10.1242/cs.118596

Erosive Arthritis and Hepatic Granuloma Formation Induced by Peptidoglycan Polysaccharide in Rats Is Aggravated by Prasugrel Treatment

Authors

Analia E. Garcia, Mario C. Rico, Elisabetta Liverani, Raul A. DeLa Cadena, Paul F. Bray, Satya P. Kunapuli

Abstract

Administration of the thienopyridine P2Y12 receptor antagonist, clopidogrel, increased the erosive arthritis induced by peptidoglycan polysaccharide (PG-PS) in rats or by injection of the arthritogenic K/BxN serum in mice. To determine if the detrimental effects are caused exclusively by clopidogrel, we evaluated prasugrel, a third-generation thienopyridine pro-drug, that contrary to clopidogrel is mostly metabolized into its active metabolite in the intestine. Prasugrel effects were examined on the PG-PS-induced arthritis rat model. Erosive arthritis was induced in Lewis rats followed by treatment with prasugrel for 21 days. Prasugrel treated arthritic animals showed a significant increase in the inflammatory response, compared with untreated arthritic rats, in terms of augmented macroscopic joint diameter associated with significant signs of inflammation, histomorphometric measurements of the hind joints and elevated platelet number. Moreover, fibrosis at the pannus, assessed by immunofluorescence of connective tissue growth factor, was increased in arthritic rats treated with prasugrel. In addition to the arthritic manifestations, hepatomegaly, liver granulomas and giant cell formation were observed after PG-PS induction and even more after prasugrel exposure. Cytokine plasma levels of IL-1 beta, IL-6, MIP1 alpha, MCP1, IL-17 and RANTES were increased in arthritis-induced animals. IL-10 plasma levels were significantly decreased in animals treated with prasugrel. Overall, prasugrel enhances inflammation in joints and liver of this animal model. Since prasugrel metabolites inhibit neutrophil function ex-vivo and the effects of both clopidogrel and prasugrel metabolites on platelets are identical, we conclude that the thienopyridines metabolites might exert non-platelet effects on other immune cells to aggravate inflammation.

Link to Article

http://dx.doi.org/10.1371/journal.pone.0069093

The Interleukin 8 Expression and its Possible Relationship with Degenerated and Injured Human Intervertebral Discs

Authors

Basit Saleem Qazi, Tang Kai and Asma Saleem Qazi

Abstract

Purpose: Cervical and Lumbar degenerative disc diseases (DDD) are a common disease of advanced age characterized by progressive changes in the intervertebral disc and associated structures. There have been great efforts for years to explain its pathophysiological mechanism(s). This study aims to provide the expression of IL-8 in a population of patients with lumbar disc herniation, cervical stenosis and vertebral fracture. Material and methods: We compared the level of IL-8 expression in the non-degenerated and degenerated intervertebral disc samples obtained from patients who underwent surgery for vertebral fracture (non degenerated disc), lumbar disc herniation and cervical stenosis (degenerated disc), whose clinical and radiological features were suggestive of disc degeneration. IL-8 expression was studied by using the western blot, immunohistochemistry and enzyme linked immune absorbent assay methods. This study includes comparison of IL-8 concentration in groups based on patient’s age and diagnosis. Results: Significantly higher levels of IL-8 expressions were found in patient with advance age, more in vertebral fracture as compared to lumbar disc herniation and cervical stenosis patients. Conclusion: The findings suggest that both local inflammatory responses occur in lumbar disc herniation, cervical stenosis and vertebral fracture patients. Using specific cytokines either by local or systemic application may reverse the degenerative process.

Link to Article

http://dx.doi.org/10.4172/2165-7939.1000135

From Meniscus to Bone: Structure and Function of Human Meniscal Entheses and Deleterious Effects of Osteoarthritis

Author

Adam Christopher Abraham

Abstract

Knee osteoarthritis plagues millions of people in the U.S. alone, yet the mechanisms of initialization are not well understood. Recent work suggests that there are a myriad of potential disease inducing routes that may give rise to this debilitating condition. Understanding and elucidating the potential pathways leading to osteoarthritis may result in novel methods of prevention and/or treatment. Human meniscus areC-shaped fibrocartilaginous structures contained within the diathroidal knee joint, the primary function of which are to provide support and lubrication between the femur and the tibia. Each knee incorporates two menisci, lateral and medial, affixed at the anterior and posterior attachment sites to the tibial plateau. Meniscal attachments, or entheses, are unique graded tissue interfaces comprised of four distinct zones that diffuse longitudinal loads transmitted via hoop stresses of collagen fibrils in the meniscal body. The attachments must remain firmly rooted to the tibial plateau to effectively attenuate joint loads. If the attachments become structurally compromised, either through direct or indirect means, excessive transverse meniscal translation results. Such joint extrusion of the meniscal body is a known precursor to developing osteoarthritis. To date there have been no investigations of integrity of meniscal attachments in the aged arthritic knee.

Link to Article

http://digitool.library.colostate.edu/exlibris/dtl/d3_1/apache_media/L2V4bGlicmlzL2R0bC9kM18xL2FwYWNoZV9tZWRpYS8yMDc0NjQ=.pdf

Astrocyte-Specific Overexpression of Insulin-Like Growth Factor-1 Protects Hippocampal Neurons and Reduces Behavioral Deficits following Traumatic Brain Injury in Mice

Authors

Sindhu K. Madathil, Shaun W. Carlson, Jennifer M. Brelsfoard, Ping Ye, A. Joseph D’Ercole, Kathryn E. Saatman

Abstract

Traumatic brain injury (TBI) survivors often suffer from long-lasting cognitive impairment that stems from hippocampal injury. Systemic administration of insulin-like growth factor-1 (IGF-1), a polypeptide growth factor known to play vital roles in neuronal survival, has been shown to attenuate posttraumatic cognitive and motor dysfunction. However, its neuroprotective effects in TBI have not been examined. To this end, moderate or severe contusion brain injury was induced in mice with conditional (postnatal) overexpression of IGF-1 using the controlled cortical impact (CCI) injury model. CCI brain injury produces robust reactive astrocytosis in regions of neuronal damage such as the hippocampus. We exploited this regional astrocytosis by linking expression of hIGF-1 to the astrocyte-specific glial fibrillary acidic protein (GFAP) promoter, effectively targeting IGF-1 delivery to vulnerable neurons. Following brain injury, IGF-1Tg mice exhibited a progressive increase in hippocampal IGF-1 levels which was coupled with enhanced hippocampal reactive astrocytosis and significantly greater GFAP levels relative to WT mice. IGF-1 overexpression stimulated Akt phosphorylation and reduced acute (1 and 3d) hippocampal neurodegeneration, culminating in greater neuron survival at 10d after CCI injury. Hippocampal neuroprotection achieved by IGF-1 overexpression was accompanied by improved motor and cognitive function in brain-injured mice. These data provide strong support for the therapeutic efficacy of increased brain levels of IGF-1 in the setting of TBI.

Link to Article

http://dx.doi.org/10.1371/journal.pone.0067204

Effect of cell-seeded hydroxyapatite scaffolds on rabbit radius bone regeneration

Authors

C. R. Rathbone, T. Guda, B. M. Singleton, D. S. Oh, M. R. Appleford, J. L. Ong, J. C. Wenke

Abstract

Highly porous hydroxyapatite (HA) scaffolds were developed as bone graft substitutes using a template coating process, characterized, and seeded with bone marrow-derived mesenchymal stem cells (BMSCs). To test the hypothesis that cell-seeded HA scaffolds improve bone regeneration, HA scaffolds without cell seeding (HA-empty), HA scaffolds with 1.5 × 104 BMSCs (HA-low), and HA scaffolds with 1.5 × 106 BMSCs (HA-high) were implanted in a 10-mm rabbit radius segmental defect model for 4 and 8 weeks. Three different fluorochromes were administered at 2, 4, and 6 weeks after implantation to identify differences in temporal bone growth patterns. It was observed from fluorescence histomorphometry analyses that an increased rate of bone infiltration occurred from 0 to 2 weeks (p < 0.05) of implantation for the HA-high group (2.9 ± 0.5 mm) as compared with HA-empty (1.8 ± 0.8 mm) and HA-low (1.3 ± 0.2 mm) groups. No significant differences in bone formation within the scaffold or callus formation was observed between all groups after 4 weeks, with a significant increase in bone regenerated for all groups from 4 to 8 weeks (28.4% across groups). Although there was no difference in bone formation within scaffolds, callus formation was significantly higher in HA-empty scaffolds (100.9 ± 14.1 mm3) when compared with HA-low (57.8 ± 7.3 mm3; p ≤ 0.003) and HA-high (69.2 ± 10.4 mm3; p ≤ 0.02) after 8 weeks. These data highlight the need for a better understanding of the parameters critical to the success of cell-seeded HA scaffolds for bone regeneration.

Link to Article

http://dx.doi.org/10.1002/jbm.a.34834