A Bisphosphonate With a Low Hydroxyapatite Binding Affinity Prevents Bone Loss in Mice After Ovariectomy and Reverses Rapidly With Treatment Cessation

Long-term consequences of osteoporosis therapy with bisphosphonates

Bisphosphonates (BPs) are medications widely used in clinical practice to treat osteoporosis and reduce fragility fractures. Its beneficial effects on bone tissue have been consolidated in the literature for the last decades. They have a high affinity for bone hydroxyapatite crystals, and most bisphosphonates remain on the bone surface for a long period of time. Benefits of long-term use of BPs: Large and important trials (Fracture Intervention Trial Long-term Extension and Health Outcomes and Reduced Incidence with Zoledronic acid Once Yearly-Pivotal Fracture Trial) with extended use of alendronate (up to 10 years) and zoledronate (up to 6 years) evidenced significant gain of bone mineral density (BMD) and vertebral fracture risk reduction. Risks of long-term use of BPs: The extended use of antiresorptive therapy has drawn attention to two extremely rare, although severe, adverse events. That is, atypical femoral fracture and medication-related osteonecrosis of the jaw are more common in patients with high cumulative doses and longer duration of therapy. BPs have demonstrated safety and effectiveness throughout the years and evidenced increased BMD and reduced fracture risks, resulting in reduced morbimortality, and improved quality of life. These benefits overweight the risks of rare adverse events.

A Comparative Study of Ultrasmall Calcium Carbonate Nanoparticles for Targeting and Imaging Atherosclerotic Plaque

Atherosclerosis is a complex disease that can lead to life-threatening events, such as myocardial infarction and ischemic stroke. Despite the severity of this disease, diagnosing plaque vulnerability remains challenging due to the lack of effective diagnostic tools. Conventional diagnostic protocols lack specificity and fail to predict the type of atherosclerotic lesion and the risk of plaque rupture. To address this issue, technologies are emerging, such as noninvasive medical imaging of atherosclerotic plaque with customized nanotechnological solutions. Modulating the biological interactions and contrast of nanoparticles in various imaging techniques, including magnetic resonance imaging, is possible through the careful design of their physicochemical properties. However, few examples of comparative studies between nanoparticles targeting different hallmarks of atherosclerosis exist to provide information about the plaque development stage. Our work demonstrates that Gd (III)-doped amorphous calcium carbonate nanoparticles are an effective tool for these comparative studies due to their high magnetic resonance contrast and physicochemical properties. In an animal model of atherosclerosis, we compare the imaging performance of three types of nanoparticles: bare amorphous calcium carbonate and those functionalized with the ligands alendronate (for microcalcification targeting) and trimannose (for inflammation targeting). Our study provides useful insights into ligand-mediated targeted imaging of atherosclerosis through a combination of in vivo imaging, ex vivo tissue analysis, and in vitro targeting experiments.

How Efficient are Alendronate-Nano/Biomaterial Combinations for Anti-Osteoporosis Therapy? An Evidence-Based Review of the Literature

Osteoporosis is defined as a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture. Because of the systemic nature of osteoporosis, the associated escalation in fracture risk affects virtually all skeletal sites. The problem is serious since it is estimated that more than 23 million men and women are at high risk of osteoporotic-like breakages in the European Union. Alendronate (ALN) is the most commonly prescribed oral nitrogen-containing bisphosphonate (BP) for the prevention and the therapy of osteoporosis. This is also one of the most intensely studied drugs in this field. However, ALN is characterized by restricted oral absorption and bioavailability and simultaneously its administration has serious side-effects (jaw osteonecrosis, irritation of the gastrointestinal system, nausea, musculoskeletal pain, and cardiovascular risks). Therefore, delivery systems enabling controlled release and local action of this drug are of great interest, being widely researched and presented in the literature. In this review, we discuss the current trends in the design of various types of alendronate carriers. Our paper is focused on the most recent developments in the field of nano/biomaterials-based systems for ALN delivery, including nano/microformulations, synthetic/natural polymeric and inorganic materials, hydrogel-based materials, scaffolds, coated-like structures, as well as organic-inorganic hybrids. Topics related to the treatment of complex bone diseases including osteoporosis have been covered in several more general reviews; however, the systems for this particular drug have not yet been discussed in detail.

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.

RECENT FINDINGS

Osteoclasts have been considered to be highly specialised cells that undergo apoptosis after fulfilling their function of bone resorption. However, recent studies suggest that osteoclasts are longer lived cells which migrate through vasculature and are capable of undergoing fission into a novel cell type (the osteomorph) and re-fusion in a process termed osteoclast recycling. The life cycle of the osteoclast is more complex than previously appreciated. Osteoclast recycling provides a novel mechanistic framework to examine changes in osteoclast biology in response to treatment of bone diseases and provides an exciting new avenue towards personalised medicine.