The effect of bone particle size on the histomorphometric and clinical outcomes following lateral ridge augmentation procedures. A randomized double blinded controlled trial

AUTHORS

Hussein S. Basma, Muhammad H.A. Saleh, Nico C. Geurs, Peng Li, Andrea Ravidà, Hom-Lay Wang, Ramzi V. Abou-Arraj

ABSTRACT

Background

The aim of this randomized clinical trial was to clinically and histologically compare the amount and quality of bone gained after lateral ridge augmentation (LRA) procedures performed using small (250-1000μm) versus large (1000-2000μm) particle size cortico-cancellous bone allografts at 6 months following surgical intervention.

Materials and Methods

22 patients, each presenting with ridge width less than 5mm were enrolled. Patients were randomly allocated to small (SP) and large particle (LP) size graft. The gain in ridge width at the level of the crest and 4mm apical to the crest was assessed via a standardized procedure before grafting and at time of implant placement, using a surgical caliper and a novel digital technique using cone beam computed tomography (CBCT). Six months following the procedure, trephine bone cores were taken from 19 augmented sites out of 17 patients (14/19 sites were in the posterior mandible) who completed the study for clinical, histologic and histomorphometric analysis.

Results

17 patients (19 sites) completed the study. LP size graft resulted in greater ridge width gain at the level of the crest (LP, 5.1 ± 1.7; SP, 3.7 ± 1.3 mm; p = 0.0642) and 4mm apical to the crest (LP, 5.9 ± 2.2; SP, 5.1 ± 1.8 mm; p = 0.4480) compared with the SP. No statistical significance for the bone density at the time of implant placement (p = 1.00) was found. Vital bone formation was more extensive in the SP compared with the LP 41.0 ± 10.1% vs 31.4 ± 14.8%, respectively (p = 0.05).

Conclusion

The results of the present article show a trend of higher ridge gain using LP during bone augmentation procedure. Future research with bigger sample size should confirm the results of the present article.

Phospholipase D2 controls bone homeostasis by modulating M-CSF-dependent osteoclastic cell migration and microtubule stability

AUTHORS

Hyun-Ju Kim, Dong-Kyo Lee, Xian Jin, Xiangguo Che, Sung Ho Ryu & Je-Yong Choi

ABSTRACT

Phospholipase D2 (PLD2), a signaling protein, plays a central role in cellular communication and various biological processes. Here, we show that PLD2 contributes to bone homeostasis by regulating bone resorption through osteoclastic cell migration and microtubule-dependent cytoskeletal organization. Pld2-deficient mice exhibited a low bone mass attributed to increased osteoclast function without altered osteoblast activity. While Pld2 deficiency did not affect osteoclast differentiation, its absence promoted the migration of osteoclast lineage cells through a mechanism involving M-CSF-induced activation of the PI3K–Akt–GSK3β signaling pathway. The absence of Pld2 also boosted osteoclast spreading and actin ring formation, resulting in elevated bone resorption. Furthermore, Pld2 deletion increased microtubule acetylation and stability, which were later restored by treatment with a specific inhibitor of Akt, an essential molecule for microtubule stabilization and osteoclast bone resorption activity. Interestingly, PLD2 interacted with the M-CSF receptor (c-Fms) and PI3K, and the association between PLD2 and c-Fms was reduced in response to M-CSF. Altogether, our findings indicate that PLD2 regulates bone homeostasis by modulating osteoclastic cell migration and microtubule stability via the M-CSF-dependent PI3K–Akt–GSK3β axis.

Disrupted development from head to tail: Pervasive effects of postnatal restricted resources on neurobiological, behavioral, and morphometric outcomes

AUTHORS

Molly H. Kent, Joanna C. Jacob, Gabby Bowen, Janhavi Bhalerao, Stephanie Desinor, Dylan Vavra, Danielle Leserve, Kelly R. Ott, Benjamin Angeles, Michael Martis, Katherine Sciandra, Katherine Gillenwater, Clark Glory, Eli Meisel, Allison Choe, Rene Olivares-Navarrete, Jennifer L. Puetzer, and Kelly Lambert

ABSTRACT

When a maternal rat nurtures her pups, she relies on adequate resources to provide optimal care for her offspring. Accordingly, limited environmental resources may result in atypical maternal care, disrupting various developmental outcomes. In the current study, maternal Long-Evans rats were randomly assigned to either a standard resource (SR) group, provided with four cups of bedding and two paper towels for nesting material or a limited resource (LR) group, provided with a quarter of the bedding and nesting material provided for the SR group. Offspring were monitored at various developmental phases throughout the study. After weaning, pups were housed in same-sex dyads in environments with SRs for continued observations. Subsequent behavioral tests revealed a sex × resource interaction in play behavior on PND 28; specifically, LR reduced play attacks in males while LR increased play attacks in females. A sex × resource interaction was also observed in anxiety-related responses in the open field task with an increase in thigmotaxis in LR females and, in the social interaction task, females exhibited more external rears oriented away from the social target. Focusing on morphological variables, tail length measurements of LR males and females were shorter on PND 9, 16, and 21; however, differences in tail length were no longer present at PND 35. Following the behavioral assessments, animals were perfused at 56 days of age and subsequent immunohistochemical assays indicated increased glucocorticoid receptors in the lateral habenula of LR offspring and higher c-Fos immunoreactivity in the basolateral amygdala of SR offspring. Further, when tail vertebrae and tail tendons were assessed via micro-CT and hydroxyproline assays, results indicated increased trabecular separation, decreased bone volume fraction, and decreased connectivity density in bones, along with reduced collagen concentration in tendons in the LR animals. In sum, although the restricted resources only persisted for a brief duration, the effects appear to be far-reaching and pervasive in this early life stress animal model.

Reactivation of Bone Lining Cells are Attenuated Over Repeated Anti-sclerostin Antibody Administration

AUTHORS

A Ram Hong, Jae-Yeon Yang, Ji Yeon Lee, Joonho Suh, Yun-Sil Lee, Jung-Eun Kim & Sang Wan Kim

ABSTRACT

Reactivation of bone lining cells (BLCs) is a crucial mechanism governing the anabolic action of anti-sclerostin antibody (Scl-Ab) via modeling-based bone formation; however, it remains unclear whether this reactivation can be attenuated after persistent administration of Scl-Ab. Here, we aimed to investigate the reproducibility of persistent Scl-Ab administration for the reactivation of BLCs, and to elucidate the relationship between the activity of BLCs and serum levels of N-terminal procollagen type I (P1NP) during chronic Scl-Ab administration. We conducted an osteoblast lineage tracing study. Briefly, Dmp1-CreERt2(+):Rosa26R mice were injected with 1 mg of 4-hydroxy-tamoxifen weekly from postnatal weeks four to eight. Mice were treated twice with either vehicle or Scl-Ab (25 mg/kg) at weeks 12, 16, and 20, and were euthanized at weeks 8, 12, 13, 16, 17, 20, and 21 (4–6 mice in each group). After euthanization, the number and thickness of X-gal (+) cells on the periosteum of the femoral bones and the serum levels of P1NP were quantified at each time point. Scl-Ab induced a significant increase in the thickness of X-gal (+) cells on periosteal bone surfaces at postnatal weeks 13 (after 1st dose), 17 (after 2nd dose), and 21 (after 3rd dose) compared to that in vehicle-treated mice (all P < 0.001). In the Scl-Ab group, significant increases in the thickness of labeled cells were observed between weeks 16 and 17 and weeks 20 and 21 (both P < 0.001). The percentage increase in X-gal (+) cell thickness was 108.9% from week 12 to week 13, 54.6% from week 16 to week 17, and 49.2% from week 20 to week 21 in the Scl-Ab group. Although Scl-Ab treatment increased the serum levels of P1NP at postnatal weeks 13 and 17 compared with those at week 12 (P = 0.017 and P = 0.038, respectively), the same was not observed at week 21 (P = 0.296). A significant increase in P1NP levels was observed between weeks 16 and 17 and weeks 20 and 21 in the Scl-Ab group (P = 0.005 and P = 0.007, respectively). The percentage increase in P1NP levels was 141.7% from weeks 12 to 13, 114.8% from weeks 16 to 17, and 99.4% from weeks 20 to 21. Serum P1NP levels were positively correlated with X-gal (+) cell thickness (R2 = 0.732, P < 0.001). Reactivation of BLCs is modestly attenuated, but reproducible, during persistent Scl-Ab administration. Serum P1NP levels appear to be an indicator of the impact of Scl-Ab on the conversion of BLCs into mature osteoblasts on periosteal bone surfaces, thus contributing to modeling-based bone formation.

Antifibrotic Effects of (−)-Epicatechin on High Glucose Stimulated Cardiac Fibroblasts

AUTHORS

Alejandra Garate-Carrillo, Israel Ramirez-Sanchez, Justina Nguyen, Julisa Gonzalez, Guillermo Ceballos, and Francisco Villarreal

ABSTRACT

Cardiac fibrosis is one of the hallmarks of a diabetic cardiomyopathy. When activated, cardiac fibroblasts (CFs) increase the production of extracellular matrix proteins. Transforming growth factor (TGF)-β1 is known to mediate cardiac fibrosis through the SMAD pathway. High glucose (HG = 25 mM) cell culture media can activate CFs using TGF-β1. There is a need to identify effective antifibrotic agents. Studies in animals indicate that treatment with (−)-epicatechin (Epi) appears capable of reducing myocardial fibrosis. Epi binds to G-protein coupled estrogen receptor (GPER) and activates downstream pathways. We evaluated the potential of Epi to mitigate the development of a profibrotic phenotype in HG stimulated CFs. CF primary cultures were isolated from young male rats and were exposed for up to 48 h HG media and treated with vehicle or 1 μM Epi. Relevant profibrotic end points were measured by the use of various biochemical assays. HG exposure of CFs increased TGF-β1 protein levels by ∼15%, fibronectin ∼25%, urea levels ∼60%, proline incorporation ∼70%, and total collagen ∼15%. Epi treatment was able to significantly block HG induced increases in TGF-β1, fibronectin, urea, proline, and total collagen protein levels. GPER levels were reduced by HG and restored in CFs treated with Epi an effect associated with the activation (i.e., phosphorylation) of c-Src. Epi treatment also reverted SMAD levels. Altogether, results demonstrate that CFs cultured in HG acquire a profibrotic phenotype, which is blocked by Epi an effect, likely mediated at least, in part, by GPER effects on the SMAD/TGF-β1 pathway.

Targeting loop3 of sclerostin preserves its cardiovascular protective action and promotes bone formation

AUTHORS

Yuanyuan Yu, Luyao Wang, Shuaijian Ni, Dijie Li, Jin Liu, Hang Yin Chu, Ning Zhang, Meiheng Sun, Nanxi Li, Qing Ren, Zhenjian Zhuo, Chuanxin Zhong, Duoli Xie, Yongshu Li, Zong-Kang Zhang, Huarui Zhang, Mei Li, Zhenlin Zhang, Lin Chen, Xiaohua Pan, Weibo Xia, Shu Zhang, Aiping Lu, Bao-Ting Zhang & Ge Zhang

ABSTRACT

Sclerostin negatively regulates bone formation by antagonizing Wnt signalling. An antibody targeting sclerostin for the treatment of postmenopausal osteoporosis was approved by the U.S. Food and Drug Administration, with a boxed warning for cardiovascular risk. Here we demonstrate that sclerostin participates in protecting cardiovascular system and inhibiting bone formation via different loops. Loop3 deficiency by genetic truncation could maintain sclerostin’s protective effect on the cardiovascular system while attenuating its inhibitory effect on bone formation. We identify an aptamer, named aptscl56, which specifically targets sclerostin loop3 and use a modified aptscl56 version, called Apc001PE, as specific in vivo pharmacologic tool to validate the above effect of loop3. Apc001PE has no effect on aortic aneurysm and atherosclerotic development in ApoE−/− mice and hSOSTki.ApoE−/− mice with angiotensin II infusion. Apc001PE can promote bone formation in hSOSTki mice and ovariectomy-induced osteoporotic rats. In summary, sclerostin loop3 cannot participate in protecting the cardiovascular system, but participates in inhibiting bone formation.