Collagen V expression is crucial in regional development of the supraspinatus tendon

Authors

Brianne K. Connizzo, Sheila M. Adams, Thomas H. Adams, David E. Birk and Louis J. Soslowsky

Abstract

Manipulations in cell culture and mouse models have demonstrated that reduction of collagen V results in altered fibril structure and matrix assembly. A tissue-dependent role for collagen V in determining mechanical function was recently established, but its role in determining regional properties has not been addressed. The objective of this study was to define the role(s) of collagen V expression in establishing the site-specific properties of the supraspinatus tendon. The insertion and midsubstance of tendons from wild type, heterozygous and tendon/ligament-specific null mice were assessed for crimp morphology, fibril morphology, cell morphology, as well as total collagen and pyridinoline cross-link (PYD) content. Fibril morphology was altered at the midsubstance of both groups with larger, but fewer, fibrils and no change in cell morphology or collagen compared to the wild type controls. In contrast, a significant disruption of fibril assembly was observed at the insertion site of the null group with the presence of structurally aberrant fibrils. Alterations were also present in cell density and PYD content. Altogether, these results demonstrate that collagen V plays a crucial role in determining region-specific differences in mouse supraspinatus tendon structure.

Link to Article

http://dx.doi.org/10.1002/jor.23246

Bone-marrow-derived mesenchymal stem cells inhibit gastric aspiration lung injury and inflammation in rats

Authors

Jing Zhou, Liyan Jiang, Xuan Long, Cuiping Fu, Xiangdong Wang, Xiaodan Wu, Zilong Liu, Fen Zhu, Jindong Shi and Shanqun Li

Abstract

Gastric aspiration lung injury is one of the most common clinical events. This study investigated the effects of bone-marrow-derived mesenchymal stem cells (BMSCs) on combined acid plus small non-acidified particle (CASP)-induced aspiration lung injury. Enhanced green fluorescent protein (EGFP+) or EGFP− BMSCs or 15d-PGJ2 were injected via the tail vein into rats immediately after CASP-induced aspiration lung injury. Pathological changes in lung tissues, blood gas analysis, the wet/dry weight ratio (W/D) of the lung, levels of total proteins and number of total cells and neutrophils in bronchoalveolar lavage fluid (BALF) were determined. The cytokine levels were measured using ELISA. Protein expression was determined by Western blot. Bone-marrow-derived mesenchymal stem cells treatment significantly reduced alveolar oedema, exudation and lung inflammation; increased the arterial partial pressure of oxygen; and decreased the W/D of the lung, the levels of total proteins and the number of total cells and neutrophils in BALF in the rats with CASP-induced lung injury. Bone-marrow-derived mesenchymal stem cells treatment decreased the levels of tumour necrosis factor-α and Cytokine-induced neutrophil chemoattractant (CINC)-1 and the expression of p-p65 and increased the levels of interleukin-10 and 15d-PGJ2 and the expression of peroxisome proliferator-activated receptor (PPAR)-γ in the lung tissue in CASP-induced rats. Tumour necrosis factor-α stimulated BMSCs to secrete 15d-PGJ2. A tracking experiment showed that EGFP+ BMSCs were able to migrate to local lung tissues. Treatment with 15d-PGJ2 also significantly inhibited CASP-induced lung inflammation and the production of pro-inflammatory cytokines. Our results show that BMSCs can protect lung tissues from gastric aspiration injury and inhibit lung inflammation in rats. A beneficial effect might be achieved through BMSC-derived 15d-PGJ2 activation of the PPAR-γ receptor, reducing the production of proinflammatory cytokines.

Link to Article

http://dx.doi.org/10.1111/jcmm.12866

Intrinsic mechanical behavior of femoral cortical bone in young, osteoporotic and bisphosphonate-treated individuals in low- and high energy fracture conditions

Authors

Elizabeth A. Zimmermann, Eric Schaible, Bernd Gludovatz, Felix N. Schmidt, Christoph Riedel, Matthias Krause, Eik Vettorazzi, Claire Acevedo, Michael Hahn, Klaus Püschel, Simon Tang, Michael Amling, Robert O. Ritchie & Björn Busse

Abstract

Bisphosphonates are a common treatment to reduce osteoporotic fractures. This treatment induces osseous structural and compositional changes accompanied by positive effects on osteoblasts and osteocytes. Here, we test the hypothesis that restored osseous cell behavior, which resembles characteristics of younger, healthy cortical bone, leads to improved bone quality. Microarchitecture and mechanical properties of young, treatment-naïve osteoporosis, and bisphosphonate-treated cases were investigated in femoral cortices. Tissue strength was measured using three-point bending. Collagen fibril-level deformation was assessed in non-traumatic and traumatic fracture states using synchrotron small-angle x-ray scattering (SAXS) at low and high strain rates. The lower modulus, strength and fibril deformation measured at low strain rates reflects susceptibility for osteoporotic low-energy fragility fractures. Independent of age, disease and treatment status, SAXS revealed reduced fibril plasticity at high strain rates, characteristic of traumatic fracture. The significantly reduced mechanical integrity in osteoporosis may originate from porosity and alterations to the intra/extrafibrillar structure, while the fibril deformation under treatment indicates improved nano-scale characteristics. In conclusion, losses in strength and fibril deformation at low strain rates correlate with the occurrence of fragility fractures in osteoporosis, while improvements in structural and mechanical properties following bisphosphonate treatment may foster resistance to fracture during physiological strain rates.

Link to Article

http://dx.doi.org/10.1038/srep21072

Combined exposure to big endothelin-1 and mechanical loading in bovine sternal cores promotes osteogenesis

Authors

Luisa A. Meyer, Michael G. Johnson, Diane M. Cullen, Juan F. Vivanco, Robert D. Blank, Heidi-Lynn Ploeg, Everett L. Smith

Abstract

Increased bone formation resulting from mechanical loading is well documented; however, the interactions of the mechanotransduction pathways are less well understood. Endothelin-1, a ubiquitous autocrine/paracrine signaling molecule promotes osteogenesis in metastatic disease. In the present study, it was hypothesized that exposure to big endothelin-1 (big ET1) and/or mechanical loading would promote osteogenesis in ex vivo trabecular bone cores. In a 2 × 2 factorial trial of daily mechanical loading (−2000 με, 120 cycles daily, “jump” waveform) and big ET1 (25 ng/mL), 48 bovine sternal trabecular bone cores were maintained in bioreactor chambers for 23 days. The bone cores' response to the treatment stimuli was assessed with percent change in core apparent elastic modulus (ΔEapp), static and dynamic histomorphometry, and prostaglandin E2 (PGE2) secretion. Two-way ANOVA with a post hoc Fisher's LSD test found no significant treatment effects on ΔEapp (p = 0.25 and 0.51 for load and big ET1, respectively). The ΔEapp in the “no load + big ET1” (CE, 13 ± 12.2%, p = 0.56), “load + no big ET1” (LC, 17 ± 3.9%, p = 0.14) and “load + big ET1” (LE, 19 ± 4.2%, p = 0.13) treatment groups were not statistically different than the control group (CC, 3.3% ± 8.6%). Mineralizing surface (MS/BS), mineral apposition (MAR) and bone formation rates (BFR/BS) were significantly greater in LE than CC (p = 0.037, 0.0040 and 0.019, respectively). While the histological bone formation markers in LC trended to be greater than CC (p = 0.055, 0.11 and 0.074, respectively) there was no difference between CE and CC (p = 0.61, 0.50 and 0.72, respectively). Cores in LE and LC had more than 50% greater MS/BS (p = 0.037, p = 0.055 respectively) and MAR (p = 0.0040, p = 0.11 respectively) than CC. The BFR/BS was more than two times greater in LE (p = 0.019) and LC (p = 0.074) than CC. The PGE2 levels were elevated at 8 days post-osteotomy in all groups and the treatment groups remained elevated compared to the CC group on days 15, 19 and 23. The data suggest that combined exposure to big ET1 and mechanical loading results in increased osteogenesis as measured in biomechanical, histomorphometric and biochemical responses.

Link to Article

http://dx.doi.org/10.1016/j.bone.2016.02.001

Three dimensional printed macroporous polylactic acid/hydroxyapatite composite scaffolds for promoting bone formation in a critical-size rat calvarial defect model

Authors

Haifeng Zhang, Xiyuan Mao, Zijing Du, Wenbo Jiang, Xiuguo Han, Danyang Zhao, Dong Han & Qingfeng Li

Abstract

We have explored the applicability of printed scaffold by comparing osteogenic ability and biodegradation property of three resorbable biomaterials. A polylactic acid/hydroxyapatite (PLA/HA) composite with a pore size of 500 μm and 60% porosity was fabricated by three-dimensional printing.3D printed PLA/HA,

β-tricalcium phosphate (β-TCP) and partially demineralized bone matrix (DBM) seeded with bone marrow stromal cells (BMSCs) were evaluated by cell adhesion, proliferation, alkaline phosphatase activity and osteogenic gene expression of osteopontin (OPN) and collagen type I (COL-1).Moreover, the biocompatibility,

bone repairing capacity and degradation in three different bone substitute materials were estimated using a critical-size rat calvarial defect model in vivo. The defects were evaluated by micro-computed tomography and histological analysis at 4 and 8weeks after surgery, respectively. The results showed that each of the studied scaffolds own its specific merits and drawbacks. 3D printed PLA/HA scaffolds possessed good biocompatibility and stimulated BMSCs cell proliferation and differentiation to osteogenic cells. And the outcomes in vivo revealed that 3D printed PLA/HA scaffolds had good osteogenic capability and biodegradation activity with no difference inflammation reaction. Therefore, 3D printed PLA/HA scaffolds have the potential applications in bone tissue engineering and may be used as graft substitutes in reconstructive surgery

Link to Article

http://www.tandfonline.com/doi/pdf/10.1080/14686996.2016.1145532

Theophylline, a methylxanthine drug induces osteopenia and alters calciotropic hormones, and prophylactic vitamin D treatment protects against these changes in rats

Authors

Subhashis Pal, Kainat Khan, Shyamsundar Pal China, Monika Mittal, Konica porwal, Richa Shrivastava, Isha Taneja, Zakir Hossain, Dhanaraju Mandalapu, Jiaur R. Gayen, Muhammad Wahajuddin, Vishnu Lal Sharma, Arun K. Trivedi, Sabyasachi Sanyal, Smrati Bhadauria, Madan M. Godbole, Sushil K. Gupta, Naibedya Chattopadhyay

Abstract

The drug, theophylline is frequently used as an additive to medications for people suffering from chronic obstructive pulmonary diseases (COPD). We studied the effect of theophylline in bone cells, skeleton and parameters related to systemic calcium homeostasis. Theophylline induced osteoblast apoptosis by increasing reactive oxygen species production that was caused by increased cAMP production. Bone marrow levels of theophylline were higher than its serum levels, indicating skeletal accumulation of this drug. When adult Sprague-Dawley rats were treated with theophylline, bone regeneration at fracture site was diminished compared with control. Theophylline treatment resulted in a time-dependent (at 4- and 8 weeks) bone loss. At 8 weeks, a significant loss of bone mass and deterioration of microarchitecture occurred and the severity was comparable to methylprednisone. Theophylline caused formation of hypomineralized osteoid and increased osteoclast number and surface. Serum bone resorption and formation marker were respectively higher and lower in the theophylline group compared with control. Bone strength was reduced by theophylline treatment. After 8 weeks, serum 25-D3 and liver 25-hydroxylases were decreased in theophylline group than control. Further, theophylline treatment reduced serum 1, 25-(OH)2 vitamin D3 (1,25-D3), and increased parathyroid hormone and fibroblast growth factor-23. Theophylline treated rats had normal serum calcium and phosphate but displayed calciuria and phosphaturia. Co-administration of 25-D3 with theophylline completely abrogated theophylline-induced osteopenia and alterations in calcium homeostasis. In addition, 1,25-D3 protected osteoblasts from theophylline-induced apoptosis and the attendant oxidative stress. We conclude that theophylline has detrimental effects in bone and prophylactic vitamin D supplementation to subjects taking theophylline could be osteoprotective.

Link to Article

http://dx.doi.org/10.1016/j.taap.2016.02.002