Biomineralization

This open access book is the proceedings of the 14th International Symposium on Biomineralization (BIOMIN XIV) held in 2017 at Tsukuba. Over the past 45 years, biomineralization research has unveiled details of the characteristics of the nano-structure of various biominerals; the formation mechanism of this nano-structure, including the initial stage of crystallization; and the function of organic matrices in biominerals, and this knowledge has been applied to dental, medical, pharmaceutical, materials, agricultural and environmental sciences and paleontology. As such, biomineralization is an important interdisciplinary research area, and further advances are expected in both fundamental and applied research

High-Resolution Quantitative Cone-Beam Computed Tomography: Systems, Modeling, and Analysis for Improved Musculoskeletal Imaging

This dissertation applies accurate models of imaging physics, new high-resolution imaging hardware, and novel image analysis techniques to benefit quantitative applications of x-ray CT in in vivo assessment of bone health. We pursue three Aims: 1. Characterization of macroscopic joint space morphology, 2. Estimation of bone mineral density (BMD), and 3. Visualization of bone microstructure. This work contributes to the development of extremity cone-beam CT (CBCT), a compact system for musculoskeletal (MSK) imaging. Joint space morphology is characterized by a model which draws an analogy between the bones of a joint and the plates of a capacitor. Virtual electric field lines connecting the two surfaces of the joint are computed as a surrogate measure of joint space width, creating a rich, non-degenerate, adaptive map of the joint space. We showed that by using such maps, a classifier can outperform radiologist measurements at identifying osteoarthritic patients in a set of CBCT scans. Quantitative BMD accuracy is achieved by combining a polyenergetic model-based iterative reconstruction (MBIR) method with fast Monte Carlo (MC) scatter estimation. On a benchtop system emulating extremity CBCT, we validated BMD accuracy and reproducibility via a series of phantom studies involving inserts of known mineral concentrations and a cadaver specimen. High-resolution imaging is achieved using a complementary metal-oxide semiconductor (CMOS)-based x-ray detector featuring small pixel size and low readout noise. A cascaded systems model was used to performed task-based optimization to determine optimal detector scintillator thickness in nominal extremity CBCT imaging conditions. We validated the performance of a prototype scanner incorporating our optimization result. Strong correlation was found between bone microstructure metrics obtained from the prototype scanner and µCT gold standard for trabecular bone samples from a cadaver ulna. Additionally, we devised a multiresolution reconstruction scheme allowing fast MBIR to be applied to large, high-resolution projection data. To model the full scanned volume in the reconstruction forward model, regions outside a finely sampled region-of-interest (ROI) are downsampled, reducing runtime and cutting memory requirements while maintaining image quality in the ROI

Recessive Osteogenesis Imperfecta: Prevalence and Pathophysiology of Collagen Prolyl-3-Hydroxylation Complex Defects

Osteogenesis Imperfecta (OI) is a clinically and genetically heterogeneous heritable bone dysplasia occurring in 1/15,000-20,000 births. OI is a collagen-related disorder, with the more prevalent dominant forms caused by defects in the genes encoding the α1 and α2 chains of type I collagen (COL1A1 and COL1A2). Rare recessive forms of OI are caused by deficiency of proteins required for collagen post-translational modifications or folding. We identified deficiency of components of the ER-resident collagen prolyl 3-hydroxylase (P3H) complex as a cause of recessive OI. The P3H complex, consisting of prolyl 3-hydroxylase 1 (P3H1), cartilage-associated protein (CRTAP) and cyclophilin B/peptidyl-prolyl isomerase B (CyPB/PPIB), modifies the α1(I) P986 and α2(I) P707 residues of type I collagen. The most common P3H complex defects occur in LEPRE1, the gene encoding P3H1, and over one-third of these cases are due to a founder mutation we identified among individuals of West African and African American descent. Our screening of contemporary cohorts revealed that 0.4% of African Americans and nearly 1.5% of West Africans are carriers for this mutation, predicting a West African frequency of recessive OI due to homozygosity for this mutation at 1/18,260 births, equal to de novo dominant OI. Furthermore, haplotype analysis of affected families was consistent with a single founder for this mutation, occurring 650-900 years ago (1100-1350 C.E.). Patients deficient in P3H1 and CRTAP have consistent bone phenotypes and collagen biochemistry. However, the rare cases of CyPB deficiency have variable findings distinct from P3H1/CRTAP. To clarify the OI mechanism of CyPB deficiency, we generated a Ppib knock-out mouse. In the absence of CyPB, only residual collagen prolyl 3-hydroxylation is detectable in KO cells and tissues. The delay in collagen folding in KO cells is further increased upon cyclophilin inhibition, supporting CyPB's role as an isomerase and the presence of redundancy for collagen ER PPIases. Site-specific alterations of collagen post-translational modification, particularly at residues involved in helical crosslinking, suggest that CyPB is critical to the function of collagen hydroxylases, especially LH1. Thus our studies indicate novel roles for CyPB, separate from the P3H complex, which directly and indirectly regulate collagen biosynthesis and bone development

Texture and Colour in Image Analysis

Research in colour and texture has experienced major changes in the last few years. This book presents some recent advances in the field, specifically in the theory and applications of colour texture analysis. This volume also features benchmarks, comparative evaluations and reviews

Novel Models to Image and Quantify Bone Drug Efficacy and Disease Progression In Vivo: Addressing the Fragility Phenotype

Bone is a composite biomaterial of mineral crystals, organic matrix, and water. Each contributes to bone quality and strength and may change independently, or together, with disease progression and treatment. Even so, there is a near ubiquitous reliance on ionizing x-ray-based approaches to characterize bone mineral density (BMD) which only accounts for ~60% of bone strength and may not adequately predict fracture risk. In a rare and severe bone disease such as osteogenesis imperfecta (OI), the hallmark genotypic and phenotypic variability makes clinical management particularly challenging. Treatment strategies rely on anti-resorptive bisphosphonates which address osteoclastic, but not osteoblastic deficiencies. Radiographic characterization of efficacy identifies structural, but not biomaterial-level alterations. Together, there is an unmet need for improved treatment strategies and means to longitudinally monitor treatment outcomes at the biomaterial-level to improve clinical management of bone disease. This thesis will describe a novel model to understand and predict individual patient treatment response to an emerging therapeutic, sclerostin antibody (SclAb) prior to clinical exposure. We then challenge the current bone imaging gold-standard with the characterization of a novel zero echo time (ZTE) magnetic resonance imaging (MRI) technique that may hold promise in identifying matrix-level and biochemical changes characteristic of OI and other diseases. SclAb has gained interest as a promising bone-forming therapeutic suggesting a novel treatment strategy through inhibition of endogenous sclerostin but effects in human pediatric OI bone remains unknown. We treated bone samples retrieved from pediatric OI patients during surgery with SclAb in vitro and quantified transcriptional response of Wnt-related genes. Results demonstrated a bone-forming response in a manner paralleling pre-clinical experience. Factors inherent to the unique phenotypic/genotypic patient profile such as the patient’s baseline cellular phenotype appear to govern response magnitude; OI patients with low untreated expression of osteoblast-related genes demonstrated the greatest magnitude of upregulation during treatment. To expand findings in vivo, we developed a novel OI xenograft model where bone was implanted into a host-derived microenvironment. The model was efficacious; bone was bioaccessible by the host and retained patient-derived bone cells throughout implantation. Treatment increased bone density and volume with a variable outcome between cortical and trabecular bone. Patients with low baseline osterix demonstrated robust human-derived osterix-expression with treatment supporting in vitro findings. The validated xenograft model can be used to establish patient-specific factors influencing treatment response suggesting a personalized medicine approach to managing OI. Characterization of treatment efficacy for OI, as well as other metabolic bone diseases, is complicated by the lack of imaging modality able to safely monitor material-level and biochemical changes in vivo. To improve upon BMD, we tested the efficacy of a 3D ZTE-MRI approach in an estrogen-deficient (OVX) model of osteoporosis during growth. ZTE-MRI-derived BMD correlated significantly with BMD measured using the gold standard, µCT, which significantly increased longitudinally over the duration of the study. Growth appeared to overcome estrogen-deficient changes in bone mass yet ZTE-MRI detected significant changes consistent with estrogen deficiency by ten weeks in cortical water, cortical matrix organization (T1) and marrow fat. Findings point to ZTE-MRI’s ability to quantify BMD in good agreement with the gold standard and detect biochemical alterations consistent with disease independent of the mineral phase suggesting its value for bone imaging. Together, results from this thesis indicate a new treatment design and non-ionizing imaging strategy to improve management of bone diseases such as OI.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/149889/1/rachelks_1.pd

Osteocalsin: Novel insights into the use of osteocalcin as a determinant of bone metabolism

Siirretty Doriast

A Study of the Subchondral Bone in Human Knee Osteoarthritis using Raman Spectroscopy

Osteoarthritis (OA) is a common, debilitating disease, involving degeneration of cartilage and bone in synovial joints. Subtle changes in the molecular structure of subchondral bone matrix occur and may precede gross morphological changes in the osteoarthritic joint. In this thesis, the analytical technique Raman Spectroscopy (which uses a monochromatic light source to probe chemical composition) is used to explore the hypothesis that subchondral bone changes occur prior to and during joint degeneration. The question is approached by looking at excised tibial plateaus from patients undergoing total knee replacement for advanced OA of the knee and comparing them with tibial plateaus from healthy joints. The samples were analysed with Raman spectroscopy, peripheral quantitative computed tomography (pQCT) and chemical analysis, to compare collagen alpha chains. The results show that bone matrix changes, related to OA, can be detected in the subchondral bone prior to overt cartilage damage, by Raman spectroscopy. These data provide support that chemical changes in bone can be related to the initiation of, or predisposition towards, joint degeneration. The results demonstrate that Raman spectroscopy should be further developed as a future tool to provide screening for early detection of joint degeneration based on correlating molecular-specific modifications in the subchondral bone

Recent Advances in Forensic Anthropological Methods and Research

Forensic anthropology, while still relatively in its infancy compared to other forensic science disciplines, adopts a wide array of methods from many disciplines for human skeletal identification in medico-legal and humanitarian contexts. The human skeleton is a dynamic tissue that can withstand the ravages of time given the right environment and may be the only remaining evidence left in a forensic case whether a week or decades old. Improved understanding of the intrinsic and extrinsic factors that modulate skeletal tissues allows researchers and practitioners to improve the accuracy and precision of identification methods ranging from establishing a biological profile such as estimating age-at-death, and population affinity, estimating time-since-death, using isotopes for geolocation of unidentified decedents, radiology for personal identification, histology to assess a live birth, to assessing traumatic injuries and so much more