A novel nano-copper-bearing stainless steel with reduced Cu2+ release only inducing transient foreign body reaction via affecting the activity of NF-κB and Caspase 3

Authors

Lei Wang, Ling Ren, Tingting Tang, Kerong Dai, Ke Yang, Yongqiang Hao

Abstract

Abstract: Foreign body reaction induced by biomaterials is a serious problem in clinical applications. Although 317L-Cu stainless steel (317L-Cu SS) is a new type of implant material with antibacterial ability and osteogenic property, the foreign body reaction level still needs to be assessed due to its Cu2+ releasing property. For this purpose, two macrophage cell lines were selected to detect cellular proliferation, apoptosis, mobility, and the secretions of inflammatory cytokines with the influence of 317L-Cu SS. Our results indicated that 317L-Cu SS had no obvious effect on the proliferation and apoptosis of macrophages; however, it significantly increased cellular migration and TNF-α secretion. Then, C57 mice were used to assess foreign body reaction induced by 317L-Cu SS. We observed significantly enhanced recruitment of inflammatory cells (primarily macrophages) with increased TNF-α secretion and apoptosis level in tissues around the materials in the early stage of implantation. With tissue healing, both inflammation and apoptosis significantly decreased. Further, we discovered that NF-κB pathway and Caspase 3 played important roles in 317L-Cu SS induced inflammation and apoptosis. We concluded that 317L-Cu SS could briefly promote the inflammation and apoptosis of surrounding tissues by regulating the activity of NF-κB pathway and Caspase 3. All these discoveries demonstrated that 317L-Cu SS has a great potential for clinical application.

Link to Article

http://dx.doi.org/10.2147/IJN.S90249

Osteoblast-specific Overexpression of Human WNT16 Increases both Cortical and Trabecular Bone Mass and Structure in Mice

Authors

Imranul Alama, Mohammed Alkhoulia, Rita L. Gerard-O’Rileya, Weston B. Wrighta, Dena Actona, Amie K. Graya, Bhavmik Patela, Austin M. Reillya, Kyung-Eun Limc, Alexander G. Roblingc, and Michael J. Econs

Abstract

Previous genome-wide association studies have identified common variants in genes associated with bone mineral density (BMD) and risk of fracture. Recently, we identified SNPs in WNT16 that were associated with peak BMD in premenopausal women. To further identify the role of Wnt16 in bone mass regulation, we created transgenic (TG) mice over-expressing human WNT16 in osteoblasts. We compared bone phenotypes, serum biochemistry, gene expression and dynamic bone histomorphometry between TG and wild-type (WT) mice. Compared to WT mice, WNT16-TG mice exhibited significantly higher whole body aBMD and BMC at 6 and 12 weeks of age in both male and female. Micro-CT analysis of trabecular bone at distal femur revealed 3-fold (male) and 14-fold (female) higher BV/TV, and significantly higher Tb.N, Tb.Th but lower Tb.Sp in TG mice compared to WT littermates in both sexes. Serum biochemistry analysis showed that male TG mice had higher serum ALP, OC, OPG, OPG/RANKL ratio as compared to WT mice. Also, lower CTX/TRAPc5b ratio was observed in TG mice compared to WT littermates in both male and female. Histomorphometry data demonstrated that both male and female TG mice had significantly higher cortical and trabecular MS/BS and BFR compared to sex-matched wild-type mice. Gene expression analysis demonstrated higher expression of Alp, OC, Opg, Opg/Rankl ratio in bone tissue in the transgenic mice compared to wild-type littermates. Our data indicate that WNT16 is critical for positive regulation of both cortical and trabecular bone mass and structure, and that this molecule might be targeted for therapeutic interventions to treat osteoporosis.

Link to Article

http://dx.doi.org/10.1210/en.2015-1281

Systemic Administration of Sclerostin Antibody Enhances Bone Morphogenetic Protein-Induced Femoral Defect Repair in a Rat Model

Authors

Brian A. Tinsley, MD; Alex Dukas, MD; Michael J. Pensak, MD; Douglas J. Adams, PhD; Amy H. Tang, BS; Michael S. Ominsky, PhD; Hua Zhu Ke, PhD; Jay R. Lieberman, MD

Abstract

Background: Recombinant human bone morphogenetic protein (rhBMP)-2 is a potent osteoinductive agent; however, its clinical use has been reduced because of safety and efficacy concerns. In preclinical studies involving a critical-sized defect in a rat model, sclerostin antibody (Scl-Ab) treatment increased bone formation within the defect but did not result in reliable healing. The purpose of the current study was to evaluate bone repair of a critical-sized femoral defect in a rat model with use of local implantation of rhBMP-2 combined with systemic administration of Scl-Ab.

Methods: A critical-sized femoral defect was created in rats randomized into three treatment groups: local rhBMP-2 and systemic Scl-Ab (Scl + BMP), local rhBMP-2 alone, and collagen sponge alone (operative control). The Scl + BMP group received local rhBMP-2 (10 μg) on a collagen sponge placed within the defect intraoperatively and then twice weekly injections of Scl-Ab (25 mg/kg) administered postoperatively. The femora were evaluated at twelve weeks with use of radiography, microcomputed tomography (microCT), histomorphometric analysis, and biomechanical testing.

Results: At twelve weeks, all Scl + BMP and rhBMP-2 only samples were healed. No femora healed in the operative control group. Histomorphometric analysis demonstrated more bone in the Scl + BMP samples than in the samples treated with rhBMP-2 alone (p = 0.029) and the control samples (p = 0.003). MicroCT revealed that the Scl + BMP group had a 90% greater bone volume within the defect region compared with the rhBMP-2 group and a 350% greater bone volume compared with the operative control group (p < 0.001). Biomechanical testing showed that the group treated with Scl + BMP had greater torsional strength and rigidity compared with the rhBMP-2 group (p < 0.001 and p = 0.047) and the intact femoral control group (p < 0.001). Torque to failure was lower in the rhBMP-2 group compared with the intact femoral control group (p < 0.002). Mean energy to failure was higher in the Scl + BMP samples compared with the rhBMP-2 only samples (p = 0.001).

Conclusions: In a critical-sized femoral defect in a rat model, local rhBMP-2 combined with systemic administration of Scl-Ab resulted in more robust healing that was stronger and more rigid than results for rhBMP-2 alone and intact nonoperative femora.

Clinical Relevance: Our study demonstrated that combining an osteoinductive agent with a systemically administered antibody that promotes bone formation can enhance bone repair and has potential as a therapeutic regimen in humans.

Link to Article

http://dx.doi.org/10.2106/JBJS.O.00171

Site-specific characteristics of bone marrow mesenchymal stromal cells modify the effect of aging on the skeleton

Authors

Dr. Xing Wang, Xuan Zou, Dr. Jing Zhao, Dr. Xia Wu, Dr. Lin Feng, Dr. Lingling E, Dongsheng Wang, Guilan Zhang, Dr. Helin Xing, and Dr. Hongchen Liu

Abstract

Bone is a self-renewing tissue. Bone marrow mesenchymal stromal cells (BMSCs) are located in the adult skeleton and are believed to be involved in the maintenance of skeletal homeostasis throughout life. With increasing age, the ability of the skeleton to repair itself decreases, possibly due to the reduced functional capacity of BMSCs. Recent evidence has suggested the existence of at least two populations of BMSCs with different embryonic origins that cannot be interchanged during stem cell recruitment: craniofacial BMSCs (neural crest origin) and appendicular BMSCs (mesoderm origin). Questions arise as to whether the site-specific characteristics alter the effect of aging on the skeleton. In this study, the effects of biological aging on human BMSCs were compared with BMSCs derived from craniofacial bone vs. BMSCs derived from the appendicular skeleton. The phenotype, proliferation and functional characteristics (osteogenic differentiation, cytokine secretion and bone formation in vivo) of the BMSCs were investigated. The results demonstrated that the proliferative capacity and osteogenic differentiation of the BMSCs decrease significantly with age both in vitro and in vivo. For age-matched groups, the osteogenic differentiation capacity of alveolar BMSCs was higher than that of femoral BMSCs in the middle-aged and old groups while there was no significant difference for the young groups. Compared with old alveolar BMSCs, old femoral BMSCs had a significantly longer population doubling time, a smaller colony-forming population and less bone formation in vivo while there was no significant difference for the young and middle-aged groups. Distinct differences in the expression of cytokine factors were also found. In conclusion, human BMSCs display an age-related decrease in functional capacity, and embryonic origins may play a critical role in mediating the aging rate of BMSCs. These data provide novel insights into the skeletal site-specific characteristics of aged BMSCs.

Link to Article

http://dx.doi.org/10.1089/rej.2015.1766

Hydrogen Sulfide Is a Novel Regulator of Bone Formation Implicated in the Bone Loss Induced by Estrogen Deficiency

Authors

Francesco Grassi, Abdul Malik Tyagi, John W. Calvert, Laura Gambari, Lindsey D. Walker, Mingcan Yu, Jerid Robinson, Jau-Yi Li, Gina Lisignoli, Chiara Vaccaro, Jonathan Adams, and Roberto Pacifici

Abstract

Hydrogen sulfide (H2S) is a gasotransmitter known to regulate bone formation and bone mass in unperturbed mice. However, it is presently unknown whether H2S plays a role in pathologic bone loss. Here we show that ovariectomy (ovx), a model of postmenopausal bone loss, decreases serum H2S levels and the bone marrow (BM) levels of two key H2S-generating enzymes, cystathione β-synthase (CBS) and cystathione γ-lyase (CSE). Treatment with the H2S-donor GYY4137 (GYY) normalizes serum H2S in ovx mice, increases bone formation and completely prevents the loss of trabecular bone induced by ovx. Mechanistic studies revealed that GYY increases murine osteoblastogenesis by activating Wnt signaling through increased production of the Wnt ligands Wnt16, Wnt2b, Wnt6 and Wnt10b in the BM. Moreover, in vitro treatment with 17β-estradiol upregulates the expression of CBS and CSE in human BM stromal cells (hSCs), while a H2S-releasing drug induces osteogenic differentiation of hSCs. In summary, regulation of H2S levels is a novel mechanism by which estrogen stimulates osteoblastogenesis and bone formation in mice and human cells. Blunted production of H2S contributes to ovx induced bone loss in mice by limiting the compensatory increase in bone formation elicited by ovx. Restoration of H2S levels is a potential novel therapeutic approach for postmenopausal osteoporosis.

Link to Article

http://dx.doi.org/10.1002/jbmr.2757

Gut-derived serotonin induced by depression promotes breast cancer bone metastasis through the RUNX2/PTHrP/RANKL pathway in mice

Authors

Jian‑Chun Zong, Xing Wang, Xiang Zhou, Chen Wang, Liang Chen, Liang‑Jun Yin, Bai‑Cheng He, Zhong‑Liang Deng

Abstract

Breast cancer metastasizes to the bone in a majority of patients with advanced disease resulting in bone destruction. The underlying mechanisms are complex, and both processes are controlled by an interaction between locally and systemically derived signals. Clinically, breast cancer patients with depression have a higher risk of bone metastasis, yet the etiology and mechanisms are yet to be elucidated. MDA‑MB‑231 breast cancer cells were used to establish a bone metastasis model by using intracardiac injection in nude mice. Chronic mild stress (CMS) was chosen as a model of depression in mice before and after inoculation of the cells. Knockdown of the RUNX‑2 gene was performed by transfection of the cells with shRNA silencing vectors against human RUNX‑2. A co‑culture system was used to test the effect of the MDA‑MB‑231 cells on osteoclasts and osteoblasts. RT‑PCR and western blotting were used to test gene and protein expression, respectively. We confirmed that depression induced bone metastasis by promoting osteoclast activity while inhibiting osteoblast differentiation. Free serotonin led to an increase in the expression of RUNX2 in breast cancer cells (MDA‑MB‑231), which directly inhibited osteoblast differentiation and stimulated osteoclast differentiation by the PTHrP/RANKL pathway, which caused bone destruction and formed osteolytic bone lesions. Additionally, the interaction between depression and breast cancer cells was interrupted by LP533401 or RUNX2 knockdown. In conclusion, depression promotes breast cancer bone metastasis partly through increasing levels of gut‑derived serotonin. Activation of RUNX2 in breast cancer cells by circulating serotonin appears to dissociate coupling between osteoblasts and osteoclasts, suggesting that the suppression of gut‑derived serotonin decreases the rate of breast cancer bone metastasis induced by depression.

Link to Article

http://www.spandidos-publications.com/10.3892/or.2015.4430