Bone Abstracts

Objectives: Studies indicate that later puberty is associated with lower bone mineral density (BMD) in childhood. Less is known about effects of puberty timing on long-term bone accrual. We examined association between age at puberty and BMD accrual rate from 10 to 25 years.Methods: This was a prospective birth cohort of healthy largely European people born in southwest England in 1991–1992 and regularly follow-up from birth to mean age 25 years. Ag...

Objectives: High prevalence (20%) of adolescent pregnancy (AP) (1) is observed in India. Reports suggest that pregnancy during adolescence may have deleterious effects on peak bone mass (2). Few reports have described the long-term effects of history of AP on bone. The objective of this study was to compare bone density and geometry of premenopausal women having delivered first child during adolescence (before age of 19 years) or after 19 years.Methods: ...

Objectives: Osteocytes play a major role in bone metabolism as mechanosensors, key regulators of osteoblast and osteoclast activity and of the mineral homeostasis. Therefore the assessment of osteocytes characteristics is important to understand bone pathology. We propose to study indirectly the osteocytes by performing quantitative backscattered electron imaging to quantify the sectioned osteocyte lacunae density and size in 2D on bone samples.Methods: ...

Objectives: Maternal vitamin D status in pregnancy is associated with neonatal bone mass, and altered DNA methylation. Mice exposed to early life vitamin D deficiency have lower bone mass and reduced bone accrual in response to mechanical loading. Using tibias from these mice we assessed DNA methylation of promoters of genetic loci important for bone growth and development.Methods: C57/BL6 mice received a vitamin D replete or deplete diet for 6 weeks per...

Objectives: Low birthweight has been shown to be associated with poorer musculoskeletal health in later life in a variety of epidemiological studies. We investigated relationships between birthweight, and grip strength or magnetic resonance imaging (MRI) measures of muscle volume in UK Biobank.Methods: UK Biobank is a large prospective cohort of men and women aged 40–69 years, including a detailed baseline assessment in which birthweight was collect...

Objectives: Limited data exist on growth parameters in children with hypophosphatasia (HPP), a rare metabolic disease characterized by impaired bone mineralization. We aimed to describe growth characteristics in untreated children with HPP enrolled in the Global HPP Patient Registry.Methods: Children (<18 years old) with a diagnosis of HPP who were not receiving enzyme replacement therapy with asfotase alfa at the time of evaluation were identified f...

Objectives: Bisphosphonates are frequently used in children with skeletal disorders, however optimal dosing and regimens are unknown. Early treatment focused on pamidronate (PAM), a second-generation formulation, however use of zoledronate (ZOL), a more potent third-generation bisphosphonate, has recently increased due to shorter and less frequent infusions. The objective of this study is to compare short-term safety of ZOL and PAM in a pediatric population.<p class="abste...

Introduction: Perthes disease (PD), idiopathic femoral head avascular necrosis, often results in deformity. The underlying cause is unclear and long-term function is directly related to the roundness of femoral head. Current treatment include mechanical treatments and various surgical procedures, which are therapeutic but can’t prevent collapse. A multicentre, prospective, randomised controlled trial of 12 months zoledronic acid (ZA) in children with PD was conducted. We ...

Objectives: We evaluated the efficacy and safety of intravenous zoledronic acid (IV ZA) in children with glucocorticoid-induced osteoporosis (GIOP) through a randomized, placebo (PBO)-controlled trial.Methods: In this multi-national Phase 3 trial (NCT00799266), children 5–17 years of age with GIOP and low-trauma vertebral fractures (VF) were randomized 1:1 to IV ZA 0.05 mg/kg or IV PBO every six months for one year. Changes in lumbar spine areal bon...

Objectives: Lysosomal diseases (LDs) are a heterogenous group of 40+ genetic disorders that can affect virtually all organs and systems, including the skeletal system. They are often caused by the loss of an enzyme critical for the breakdown of macromolecules in the lysosome, leading to accumulation of these substrates and subsequent lysosomal dysfunction. Enzyme replacement therapy (ERT) is the primary treatment option for many LDs, but several issues hinder the efficacy of t...

Objectives: While local gene therapy for bone applications has shown some success in preclinical models, systemic delivery of transgenes to the skeleton remains a considerable challenge. Viral vectors such as adeno-associated viruses (AAVs) have great potential as vectors for systemic transgene delivery and may be adapted for emerging gene editing technologies. Furthermore, AAV vectors can have high efficiency, low immunogenicity, and selective tropism towards different tissue...

Osteogenesis imperfecta (OI) is not only characterized by fragile bones but also impaired muscle mass and function. Inhibition of signaling through the activin receptor IIB has the potential to improve both muscle and bone mass. Here we investigated the effect of a soluble activin receptor IIB ligand, ACE-2494 (10 mg/kg twice a week), in 4-week old Col1a1Jrt/+ male mice, a model of severe dominant OI caused by a Col1a1 splice site mutation. Four weeks of treatment with ACE-249...

Objectives: Osteogenesis Imperfecta (OI) is a heritable brittle bone disease mainly caused by mutation of COL1A1 or COL1A2. Treatment with bisphosphonate is not effective enough in patients with severe OI. 4-phenylbutyric acid (4-PBA) may become a new medicine, which was reported to ameliorate the phenotype of an OI zebrafish model. In the present study, we aimed to analyze the pathology of OI and the effects of 4-PBA on patient-derived fibroblasts and induced pluripotent stem...

Objective: We compared the efficacy and safety of burosumab, a monoclonal antibody against FGF23, to conventional therapy [oral phosphate and active vitamin D (Pi/D)] in children with X-linked hypophosphatemia (XLH).Methods: In this Phase 3 trial (NCT02915705), 61 children with XLH (1-12 years-old) were randomized 1:1 after a 7-day Pi/D washout to receive burosumab starting at 0.8 mg/kg SC Q2W or reinitiate Pi/D optimally titrated by investigators. Eligi...

Objective: We evaluated the long-term efficacy of burosumab, a monoclonal antibody against FGF23, in a Phase 2 Study (NCT02163577) in children with XLH.Methods: Fifty-two children with XLH (5-12 years-old, Tanner ≤ 2) were randomized 1:1 to receive subcutaneous burosumab Q2W or Q4W for 64 weeks. Doses were titrated up to 2 mg/kg/dose targeting serum phosphorus levels within 1.1–1.6 mmol/l. All subjects entered the long-term extension at Week 6...

Introduction: ENPP1 Deficiency manifests as GACI type 1 in infants, a disorder characterized by extensive arterial calcifications and stenoses, often fatal in utero or in early infancy. Beyond six months, the mortality rate significantly decreases among survivors, who may later develop ARHR2, characterized clinically by short stature, bone deformities and pain. ABCC6 Deficiency also manifests as GACI type 2 in infants and is clinically indistinguishable from GACI type 1. Anima...

Objective: We constructed height growth curves for children with XLH from birth to early adolescence, a majority of whom received conventional therapy consisting of multiple daily doses of oral phosphate and active vitamin D.Methods: Growth data from four clinical studies were pooled to construct the growth curves. UX023-CL002 was an observational, retrospective chart review of 103 children with XLH, 1–14 years of age. Pre-treatment data were collec...

Objectives: Osteogenesis imperfecta (OI) displays a heterozygous phenotype even amongst similar genotypes. It has therefore been difficult to establish a mouse model which represents clinical OI in children. By engrafting human OI bone into mice we have developed a hybrid model enabling us to investigate the efficacy of new treatments for this phenotypically diverse condition.Methods: Bone chips, that would otherwise be discarded, were collected from chi...

Objectives: Osteogenesis imperfecta (OI) is a heritable disorder characterized by bone deformity and skeletal fragility. Cartilage associated protein (CRTAP), proline 3-Hydroxylase 1 (P3H1) and Cyclophylin B (PPIB) are components of the endoplasmic reticulum (ER)-resident complex involved in the 3-hydroxylation of specific proline residues in collagen type I α chains. Mutations in these proteins are responsible for recessive OI type VII, VIII and IX, respectively. Murine ...

Background: We discovered that variants in NBAS (Neuroblastoma Amplified Sequence Gene) known to be associated with acute liver failure are also responsible for skeletal abnormalities. This work was published as a novel cause of bone fragility [Balasubramanian et al., 2017]. NBAS role in bone fragility provides an opportunity to use tractable animal research to advance understanding of mechanism and identify potential new treatments. This would be beneficial to patien...

Objectives: Osteogenesis Imperfecta (OI) is a collagen-related disorder. Type V OI, caused by a recurrent dominant mutation in the plasma membrane protein IFITM5/BRIL, and type VI OI, caused by recessive null mutations in the anti-angiogenic factor PEDF, have distinct features. IFITM5 S40L, reported in six patients, causes severe dominant OI with phenotype and bone histology similar to type VI, rather than Type V, OI. Our objective is to understand the pathway connecting IFITM...

Objectives: A common feature of nearly all forms of osteogenesis imperfecta (OI) is a hypermineralized bone matrix. Null mutations in SERPINF1, encoding the potent antiangiogenic factor PEDF, lead to type VI OI with excessive osteoid formation, abnormal osteoblast-osteocyte development and increased matrix mineralization. Recently, atypical type VI OI has been delineated, caused by a loss-of-function mutation (p.S40L) in IFITM5 the causative gene for type V OI. The 6 cases rep...

Objectives: Endochondral ossification in the growth plate cartilage (GPC) plays a crucial role in the determination of the length and shape of long bones. Many skeletal dysplasias are caused by GPC dysfunction, associated with short stature. We have already reported that human iPS cell-derived cartilage (hiPSC-Cart), when implanted into the subcutaneous spaces of the SCID mice for 4 weeks, formed skeletal tissue like GPC. This model could also recapitulate the pathology of FGF...

Objectives: To assess the safety, tolerability and pharmacokinetic (PK) profile of single and multiple doses of TA-46 administered subcutaneously to healthy volunteers.Methods: This was a double-blind, randomized, placebo-controlled trial in a total of 72 subjects. Cohorts of 8 subjects were randomised to receive either TA-46 or placebo in a 3:1 ratio in single ascending dose (SAD) and multiple ascending dose (MAD) cohorts. SAD doses were 0.3, 1, 3, 10 a...

Objectives: Achondroplasia (ACH), the most common form of human dwarfism, is caused by a gain-of-function mutation in the fibroblast growth factor receptor 3 (FGFR3) gene, a key negative regulator of endochondral ossification. C-type natriuretic peptide (CNP) inhibits the FGFR3 pathway and thereby promotes proliferation and differentiation of chondrocytes to promote bone growth. TransCon CNP is a prodrug designed to provide continuous exposure to CNP to optimize efficacy with ...

Fibrodysplasia ossificans progressiva (FOP) is a rare, autosomal dominant disorder characterized by heterotopic ossification (HO) in muscles, ligaments and tendons. Flare-ups often precede formation of HO, resulting in immobilized joints. Recently, it has been shown that [18F]NaF PET/CT could identify early ossifying disease activity during flare-ups. HO may progress without signs of flare-up, but its underlying physiology is not understood. We wondered whether [18F]NaF PET/CT...

Objective: FOP is a rare, severely disabling disease characterized by episodic flare-ups and accumulation of heterotopic ossification (HO) leading to restricted movement, physical disability, and early death. Data from two Phase 2 interventional studies and one natural history study (NHS) were used to evaluate whether palovarotene could reduce HO following an FOP flare-up.Methods: HO volume at the flare-up site was determined by CT at baseline and 12 wee...