Isolation and Generation of Osteoclasts.

This chapter describes the isolation, expansion, staining, and imaging of osteoclasts from murine (MKS, BKD, and MMM) and human (NS, JBO, and KS) sources. We cover in detail both traditional and more modern methods of assessing osteoclast formation and function in vitro including advances in image acquisition and automated analyses. Importantly, we provide in-depth methods for human osteoclast culture systems, methods to assess human osteoclast function, and highlight potential methodological pitfalls and ways to overcome them.

Denosumab discontinuation in the clinic: implications of rebound bone turnover and emerging strategies to prevent bone loss and fractures.

Denosumab is a highly effective treatment for osteoporosis, and its long-term use is associated with incremental gains in BMD and sustained fracture risk reduction. Stopping denosumab, however, results in a rebound increase in bone turnover, loss of treatment-associated BMD gains, and in the worst case, spontaneous vertebral fractures (VFs). Insights into the risk factors, the underlying mechanisms for rebound-associated bone loss, and true incidence of rebound VFs are emerging.

Insights from autopsy-initiated pathological studies of the pathogenesis and clinical manifestations of atherosclerosis and ischemic heart disease: Part I. Atherosclerosis.

Context: Ischemic heart disease (IHD) due to coronary atherosclerosis constitutes the leading cause of morbidity and mortality worldwide. This review was undertaken to document the historical basis for our contemporary understanding of atherosclerosis-based disease and to provide a rationale for continued support for autopsy-based research to make further progress in reducing the morbidity and mortality from atherosclerosis-related disease.

Objectives: To analyze the contributions of the autopsy-initiated pathological studies to complement and validate other lines of investigation in determining the pathology and pathogenesis of the leading worldwide cause of morbidity and mortality, namely, atherosclerosis and its major complications of coronary atherosclerosis, ischemic heart disease, coronary thrombosis, acute myocardial infarction, and sudden cardiac death.

Insights from autopsy-initiated pathological studies of the pathogenesis and clinical manifestations of atherosclerosis and ischemic heart disease: Part II. Ischemic heart disease.

Context: Ischemic heart disease (IHD) due to coronary atherosclerosis constitutes the leading cause of morbidity and mortality worldwide. This review was undertaken to retrospectively analyze the lines of research that generated the evidence for our contemporary understanding of atherosclerosis-based coronary artery disease and to provide a rationale for continued support for autopsy-based research in order to make further progress in reduction of the morbidity and mortaility from IHD.

Objectives: To analyze the contributions of the autopsy to complement and validate other lines of investigation in determining the complex interactions between coronary artery alterations linked to the major manifestations of coronary atherosclerosis, namely, coronary thrombosis, acute myocardial infarction, and sudden cardiac death.

Early and multiple doses of zoledronate mitigates rebound bone loss following withdrawal of receptor activator of nuclear factor kappa-B ligand inhibition.

Rebound bone loss following denosumab discontinuation is an important barrier in the effective long-term treatment of skeletal disorders. This is driven by increased osteoclastic bone resorption following the offset of RANKL inhibition, and sequential osteoclast-directed therapy has been utilized to mitigate this. However, current sequential treatment strategies intervene following the offset of RANKL inhibition and this approach fails to consistently prevent bone loss.

Mapping RANKL- and OPG-expressing cells in bone tissue: the bone surface cells as activators of osteoclastogenesis and promoters of the denosumab rebound effect.

Denosumab is a monoclonal anti-RANKL antibody that inhibits bone resorption, increases bone mass, and reduces fracture risk. Denosumab discontinuation causes an extensive wave of rebound resorption, but the cellular mechanisms remain poorly characterized. We utilized in situ hybridization (ISH) as a direct approach to identify the cells that activate osteoclastogenesis through the RANKL/OPG pathway.

Cardiac Mass in a 78-Year-Old Patient With a History of Cancer: Diagnostic and Treatment Challenges.

Primary cardiac angiosarcoma is a rare, aggressive malignancy that commonly metastasizes to various organs. The presenting symptoms are typically nonspecific, so a comprehensive examination is required to confirm the diagnosis promptly. This case report describes the presentation of an older patient with a history of neoplasms.

A novel sequential treatment approach between denosumab and romosozumab in patients with severe osteoporosis.

Unlabelled: In severe osteoporosis, the optimal approach for sequential treatment between denosumab and romosozumab is unclear. We utilised a novel overlapping strategy in three patients with very-high fracture risk despite long-term denosumab which led to greater bone density improvements than previously reported with standard approaches. Larger confirmatory prospective studies are needed.

An in silico approach to elucidate the pathways leading to primary osteoporosis: age-related vs. postmenopausal.

Numerical models of bone remodelling have traditionally been used to perform in silico tests of bone loss in postmenopausal women and also to simulate the response to different drug treatments. These models simulate the menopausal oestrogen decline by altering certain signalling pathways. However, they do not consider the simultaneous effect that ageing can have on cell function and bone remodelling, and thus on bone loss.

Temporal patterns of osteoclast formation and activity following withdrawal of RANKL inhibition.

Rebound bone loss following denosumab discontinuation is an important clinical challenge. Current treatment strategies to prevent this fail to suppress the rise and overshoot in osteoclast-mediated bone resorption. In this study, we use a murine model of denosumab treatment and discontinuation to show the temporal changes in osteoclast formation and activity during RANKL inhibition and withdrawal.

The performance of artificial intelligence chatbot large language models to address skeletal biology and bone health queries.

Artificial intelligence (AI) chatbots utilizing large language models (LLMs) have recently garnered significant interest due to their ability to generate humanlike responses to user inquiries in an interactive dialog format. While these models are being increasingly utilized to obtain medical information by patients, scientific and medical providers, and trainees to address biomedical questions, their performance may vary from field to field. The opportunities and risks these chatbots pose to the widespread understanding of skeletal health and science are unknown.

New Horizons: Translational Aspects of Osteomorphs.

Osteomorphs are a newly described osteoclast lineage cell in mice, which are suggested to play a significant role in the maintenance of bone resorption. Preclinical investigations revealed that osteomorphs are generated through the fission of multinucleated bone-resorbing osteoclasts and can also re-fuse with existing osteoclasts. Modifications to RANKL signaling have been shown to alter cycles of fission and re-fusion of osteomorphs in mice.

Minimally invasive longitudinal intravital imaging of cellular dynamics in intact long bone.

Intravital two-photon microscopy enables deep-tissue imaging at high temporospatial resolution in live animals. However, the endosteal bone compartment and underlying bone marrow pose unique challenges to optical imaging as light is absorbed, scattered and dispersed by thick mineralized bone matrix and the adipose-rich bone marrow. Early bone intravital imaging methods exploited gaps in the cranial sutures to bypass the need to penetrate through cortical bone.

Increased Bone Formation and Accelerated Bone Mass Accrual in a Man Presenting with Diffuse Osteosclerosis/High Bone Mass Phenotype and Adenocarcinoma of Unknown Primary.

A 71-year-old man was referred for evaluation of incidental generalized osteosclerosis. He was found to have a high bone mass (HBM) with an elevated lumbar spine bone mineral density (BMD) Z-score of +5.3.

MCP-1 expression in breast cancer and its association with distant relapse.

Background: Distant relapse of breast cancer complicates management of the disease and accounts for 90% of breast cancer-related deaths. Monocyte chemoattractant protein-1 (MCP-1) has critical roles in breast cancer progression and is widely accepted as a pro-metastatic chemokine.

Methods: This study explored MCP-1 expression in the primary tumour of 251 breast cancer patients.

A 3--sulfated heparan sulfate dodecasaccharide (12-mer) suppresses thromboinflammation and attenuates early organ injury following trauma and hemorrhagic shock.

Introduction: Dysregulated inflammation and coagulation are underlying mechanisms driving organ injury after trauma and hemorrhagic shock. Heparan sulfates, cell surface glycosaminoglycans abundantly expressed on the endothelial surface, regulate a variety of cellular processes. Endothelial heparan sulfate containing a rare 3--sulfate modification on a glucosamine residue is anticoagulant and anti-inflammatory through high-affinity antithrombin binding and sequestering of circulating damage-associated molecular pattern molecules.

Multi-Targeting DKK1 and LRP6 Prevents Bone Loss and Improves Fracture Resistance in Multiple Myeloma.

An imbalance between bone resorption and bone formation underlies the devastating osteolytic lesions and subsequent fractures seen in more than 90% of multiple myeloma (MM) patients. Currently, Wnt-targeted therapeutic agents that prevent soluble antagonists of the Wnt signaling pathway, sclerostin (SOST) and dickkopf-1 (DKK1), have been shown to prevent bone loss and improve bone strength in preclinical models of MM. In this study, we show increasing Wnt signaling via a novel anti-low-density lipoprotein receptor-related protein 6 (LRP6) antibody, which potentiates Wnt1-class ligand signaling through binding the Wnt receptor LRP6, prevented the development of myeloma-induced bone loss primarily through preventing bone resorption.

Clinicopathological correlations in heart transplantation recipients complicated by death or re-transplantation.

Purpose: This study aimed to identify and correlate pathological findings with clinical outcomes in patients after orthotopic heart transplantation (OHT) who either died or underwent a re-transplantation.

Methodology And Study Design: Single-center retrospective analysis of primary OHT patients who died or were re-transplanted between October 2012 and July 2021. Clinical data were matched with corresponding pathological findings from endomyocardial biopsies on antibody-mediated rejection, cellular rejection, and cardiac allograft vasculopathy.

Preventing osteolytic lesions and osteomyelitis in multiple myeloma.

Multiple myeloma is a hematological malignancy affecting the plasma cells. It is the second most common hematologic cancer in adults. Over 90% of patients develop local osteolytic lesions and skeletal-related events at some point during the progression of the disease.

Osteoclast Recycling and the Rebound Phenomenon Following Denosumab Discontinuation.

Purpose Of Review: Inhibition of receptor activator of nuclear factor kappa-B ligand (RANKL) with denosumab is an effective treatment in a number of conditions including osteoporosis where suppression of bone resorption is desired. However, denosumab discontinuation is associated with rebound increase in bone resorption and subsequent loss in bone mass and a rapid return to baseline fracture risk. We review recent data on the rebound increase in bone resorption following denosumab discontinuation and the potential mechanisms behind this phenomenon.