Improvements In Bone Structure Research Articles

Multi-Targeting DKK1 and LRP6 Prevents Myeloma-Induced Bone Disease

Multiple myeloma (MM) is characterised by an expansion of malignant plasma cells in the bone marrow, systemic bone loss and destructive osteolytic bone lesions. These are mediated by an imbalance in bone remodeling, in which bone resorption is exacerbated and bone formation is suppressed. More than 90% of MM patients present with osteolytic lesions that can lead to pain and increased risk of fracture, significantly impacting their quality of life. Bone-targeted treatments currently used in the clinic can suppress lesion progression and reduce fracture risk, however these agents cannot replace lost bone and patients continue to fracture. Therapeutic strategies aimed at promoting bone formation are therefore required to overcome the loss of skeletal integrity and subsequent fractures in MM patients.Therapeutic agents that target the canonical Wnt signaling pathway, a potent regulator of bone formation, have the potential to address these skeletal complications, where they could rebuild lost bone and improve bone strength in affected individuals. We have demonstrated a novel anti-LRP6 agent, which potentiates Wnt signaling through binding the Wnt receptor LRP6, prevented the development of myeloma-induced bone loss primarily through preventing bone resorption. However, since MM patients present with both increased bone resorption and decreased bone formation, we hypothesised that combining anti-LRP6 with the bone anabolic anti-DKK1 (100mg/kg twice weekly intravenously) would lead to more robust improvements in bone structure than single treatment approaches.MicroCT analysis demonstrated a 74% increase in femoral trabecular bone volume per tissue volume (BV/TV) in naïve, non-tumour bearing mice given the combination treatment compared to control agents (p<0.0001). Mice injected with 5TGM1eGFP murine myeloma cells had a 34% reduction in femoral BV/TV compared to naïve controls (p<0.0001). Combination treatment drastically improved BV/TV in 5TGM1-bearing mice by 111% (p<0.0001), compared to control, and this improvement with the combination treatment strategy was 25% greater than anti-LRP6 single treatment approaches (p<0.001). MicroCT analysis in L4 lumbar vertebrae demonstrated similar bone structural changes in 5TGM1-bearing mice treated with the combination strategy. Consequently, this combination significantly improved resistance to fracture in L4 vertebrae in 5TGM1eGFP-bearing mice compared to their controls (p<0.001), and it provided greater protection against fracture compared to anti-LRP6 single agent treatment. Interestingly, these improvements in bone volume were primarily due to reduced bone resorption, with significant reductions in osteoclast numbers and osteoclast surface per bone surface demonstrated in 5TGM1eGFP-bearing mice treated with the combination strategy (p<0.001) compared to control. Importantly, tumour activity was not altered with either single or combination Wnt-promoting treatment strategies.This study defines a novel therapeutic strategy, which will reduce fractures and improve quality of life in patients with MM when used in combination with tumour-targeted treatments. [Display omitted] DisclosuresCong: Novartis Institutes for Biomedical Research: Current Employment. Daley: Novartis Institutes of Biomedical Research: Current Employment.

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. When combined with an agent targeting the soluble Wnt antagonist DKK1, we showed more robust improvements in bone structure than anti-LRP6 treatment alone. Micro-computed tomography (μCT) analysis demonstrated substantial increases in trabecular bone volume in naïve mice given the anti-LRP6/DKK1 combination treatment strategy compared to control agents. Mice injected with 5TGM1eGFP murine myeloma cells had significant reductions in trabecular bone volume compared to naïve controls. The anti-LRP6/DKK1 combination strategy significantly improved bone volume in 5TGM1-bearing mice by 111%, which was also superior to anti-LRP6 single treatment; with similar bone structural changes observed within L4 lumbar vertebrae. Consequently, this combination strategy significantly improved resistance to fracture in lumbar vertebrae in 5TGM1-bearing mice compared to their controls, providing greater protection against fracture compared to anti-LRP6 antibody alone. Interestingly, these improvements in bone volume were primarily due to reduced bone resorption, with significant reductions in osteoclast numbers and osteoclast surface per bone surface demonstrated in 5TGM1-bearing mice treated with the anti-LRP6/DKK1 combination strategy. Importantly, Wnt stimulation with either single or combined Wnt-targeted agents did not exacerbate tumor activity. This work provides a novel approach of targeting both membrane-bound and soluble Wnt pathway components to provide superior skeletal outcomes in patients with multiple myeloma and other bone destructive cancers. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Effects of 8-Prenylnaringenin and Whole-Body Vibration Therapy on a Rat Model of Osteopenia.

Background. 8-Prenylnaringenin (8-PN) is the phytoestrogen with the highest affinity for estrogen receptor-α (ER-α), which is required to maintain BMD. The osteoprotective properties of 8-PN have been demonstrated previously in tibiae. We used a rat osteopenia model to perform the first investigation of 8-PN with whole-body vertical vibration (WBVV). Study Design. Ovariectomy was performed on 52 of 64 Sprague-Dawley rats. Five weeks after ovariectomy, one group received daily injections (sc) of 8-PN (1.77 mg/kg) for 10 weeks; a second group was treated with both 8-PN and WBVV (twice a day, 15 min, 35 Hz, amplitude 0.47 mm). Other groups received either only WBVV or no treatment. Methods. The rats were sacrificed 15 weeks after ovariectomy. Lumbar vertebrae and femora were removed for biomechanical and morphological assessment. Results. 8-PN at a cancer-safe dose did not cause fundamental improvements in osteoporotic bones. Treatment with 8-PN caused a slight increase in uterine wet weight. Combined therapy using WBVV and 8-PN showed no significant improvements in bone structure and biomechanical properties. Conclusion. We cannot confirm the osteoprotective effects of 8-PN at a cancer-safe dose in primary affected osteoporotic bones. Higher concentrations of 8-PN are not advisable for safety reasons. Adjunctive therapy with WBVV demonstrates no convincing effects on bones.

Partial rescue of mucopolysaccharidosis type VII mice with a lifelong engraftment of allogeneic stem cells in utero.

In utero hematopoietic cell transplantation (IUHCT) has been performed in Mucopolysaccharidosis Type VII (MPSVII) mice, but a lifelong engraftment of allogeneic donor cells has not been achieved. In this study, we sought to confirm a lifelong engraftment of allogeneic donor cells immunologically matched to the mother and to achieve partial rescue of phenotypes in the original MPSVII strain through IUHCT by intravenous injection. We performed in vitro fertilization in a MPSVII murine model and transferred affected embryos to ICR/B6-GFP surrogate mothers in cases where fetuses receiving IUHCT were all homozygous. Lineage-depleted cells from ICR/B6-GFP mice were injected intravenously at E14.5. Chimerism was confirmed by flow cytometry at 4 weeks after birth, and β-glucuronidase activity in serum and several phenotypes were assessed at 8 weeks of age or later. Donor cells in chimeric mice from ICR/B6-GFP mothers were detected at death, and were confirmed in several tissues including the brains of sacrificed chimeric mice. Although the serum enzyme activity of chimeric mice was extremely low, the engraftment rate of donor cells correlated with enzyme activity. Furthermore, improvement of bone structure and rescue of reproductive ability were confirmed in our limited preclinical study. We confirmed the lifelong engraftment of donor cells in an original immunocompetent MPSVII murine model using intravenous IUHCT with cells immunologically matched to the mother without myeloablation, and the improvement of several phenotypes.

Increases in BMD Correlate With Improvements in Bone Microarchitecture With Teriparatide Treatment in Postmenopausal Women With Osteoporosis

Increases in BMD are correlated with improvements in 2D and 3D trabecular microarchitecture indices with teriparatide treatment. Therefore, improvements in trabecular bone microarchitecture may be one of the mechanisms to explain how BMD increases improve bone strength during teriparatide treatment. Bone strength is determined by BMD and other elements of bone quality, including bone microarchitecture. Teriparatide treatment increases BMD and improves both cortical and trabecular bone microarchitecture. Increases in lumbar spine (LS) BMD account for approximately 30-41% of the vertebral fracture risk reduction with teriparatide treatment. The relationship between increases in BMD and improvements in cortical and trabecular microarchitecture has not yet been studied. The relationship between increases in BMD and improvements in cortical and trabecular microarchitecture after teriparatide treatment was assessed using data from a subset of patients who had areal BMD measurements and structural parameters from transiliac bone biopsies in the Fracture Prevention Trial. 2D histomorphometric and 3D microCT parameters were measured at baseline and 12 (n = 21) or 22 (n = 36) mo. LS BMD was assessed at baseline and 12 and 18 mo, and femoral neck (FN) BMD was measured at baseline and 12 mo. Pearson correlation was performed to assess the relationship between actual changes in BMD and actual changes in microarchitectural parameters. Changes in LS BMD at 12 mo were significantly correlated with improvements in trabecular bone structure at 22 mo: 2D bone volume (r = 0.45, p = 0.02), 2D mean wall thickness (r = 0.41, p = 0.03), 3D bone volume (r = 0.48, p = 0.006), 3D trabecular thickness (r = 0.44, p = 0.01), 3D trabecular separation (r = -0.37, p = 0.04), 3D structural model index (r = -0.54, p = 0.001), and 3D connectivity density (r = 0.41, p = 0.02). Changes in LS BMD at 18 mo had similar correlations with improvements in bone structure at 22 mo. Changes in FN BMD at 12 mo were significantly correlated with changes in 2D mean wall thickness (r = 0.56, p = 0.002), 3D bone volume (r = 0.51, p = 0.004), 3D trabecular thickness (r = 0.44, p = 0.01), 3D trabecular separation (r = -0.46, p = 0.01), and 3D structural model index (r = -0.55, p = 0.001). Increases in BMD are correlated with improvements in trabecular microarchitecture in iliac crest of patients with teriparatide treatment. Therefore, improvements in trabecular bone microarchitecture may be one of the mechanisms to explain how BMD increases improve bone strength during teriparatide treatment.

Parathyroid hormone and bone quality

Bone quality has been seen as an important concept which refers to microarchitecture, bone turnover, micro-damage accumulation, and mineralization because there is no strong correlation between the increase of bone mineral density and the fracture risk reduction. Intermittent administration of parathyroid hormone (PTH) stimulates bone formation, and continuous infusion of PTH stimulates bone resorption. In the preclinical studies, intermittent administration of PTH increased bone strength in association with the increase in total body skeletal mass and the improvement of bone structure. Furthermore, the clinical studies showed that PTH improved bone structure such as trabecular connectivity and cortical thickness, as well as increased bone mass. These changes were considered to contribute to reduction of fracture risk.

Early Changes in Biochemical Markers of Bone Formation Correlate with Improvements in Bone Structure during Teriparatide Therapy

Biochemical markers of bone turnover may reflect bone structure during anabolic treatment. The objective was to evaluate associations between changes in biochemical markers and structural and dynamic bone parameters during teriparatide treatment. This study was a randomized, multicenter, double-blind, placebo-controlled fracture prevention trial, with 20-month median treatment duration for biopsy subset. The trial was conducted at 11 clinical study sites. Sixty-one postmenopausal women with osteoporosis who had paired transiliac biopsy specimens participated in the study. Once-daily sc injections of either placebo or teriparatide (20 or 40 microg) were administered. The study measured: 1) serum and urinary biochemical markers of bone formation [bone alkaline phosphatase and procollagen I C-terminal propeptide (PICP)] and resorption (N-telopeptide and deoxypyridinoline); and 2) structural and dynamic analyses of bone biopsies, including two-dimensional (2D) histomorphometry and three-dimensional (3D) micro-computed tomography evaluations measured at baseline (n = 57) and 12 (n = 21) or 22 (n = 36) months. U-N-telopeptide/creatinine and serum-PICP correlated with bone structure and dynamic indices at baseline, respectively. Changes in bone alkaline phosphatase at 1 month correlated with changes at 22 months in 2D wall thickness (r = 0.73; P = 0.001), trabecular bone volume (trabecular bone volume per total volume, BV/TV) (r = 0.58; P < 0.05), marrow star volume (r = -0.51; P = 0.05); 3D trabecular thickness (r = 0.49; P < 0.05), and BV/TV (r = 0.54; P < 0.05). Changes in PICP at 1 month correlated with changes in wall thickness (r = 0.60; P = 0.01), and 2D BV/TV (r = 0.51; P < 0.05) at 22 months. Changes in markers at 6 or 12 months were not associated with changes in structural or dynamic parameters. Early (1-month) changes in biochemical markers of bone formation, but not resorption, correlated with improvements in bone structure after 22 months of teriparatide therapy.

Golden standard of ROD management

Because of the skeletal resistance to PTH, it is still hard to assess bone turnover by serum PTH level alone in uremia. Furthermore, several questions have been raised against the accuracy of intact PTH assay. Final goal of the control of PTH secretion is to maintain normal bone metabolism. For the evaluation of bone, improvement of bone structure needs to be checked as well as that of serum bone metabolic marker and bone mineral density.

Greatly increased cancellous bone formation with rapid improvements in bone structure in the rat maternal skeleton after lactation.

There is a decrease in cancellous bone mass and strength during lactation but these are partially or completely reconstituted in the postlactational period. The purpose of this study was to determine changes in cancellous bone structure and formation after lactation in established breeder rats. For this, rats were taken at the end of the second pregnancy (Preg-2) and second lactation (Lac-2) and 2, 4, and 6 weeks after weaning. Nulliparous (NP) groups were included for comparisons. Bone structure was measured using morphometric methods and bone dynamics by histomorphometry. Tibial metaphyseal cancellous bone was lost during the first reproductive cycle, as expected, and again depleted during the Lac-2. Bone formation indices were elevated at the end of Lac-2, compared with those at the end of the second pregnancy or in the nulliparous animals. Within 2 weeks after the second weaning, the amount of double-labeled surface (dLS) increased approximately 800%, the mineralizing surface (MS) increased >400% with similar increases in bone formation rates (BFRs), compared with already elevated bone formation measured at the end of Lac-2. From 2 to 4 weeks after lactation, there were commensurate increases in cancellous bone mass and structural indices with essentially complete restoration of cancellous bone volume and structure compared with that measured at the end of Preg-2. The results show rapid and substantial increases in bone formation with reconstitution of cancellous bone mass and structure after lactation in rats. The skeletal changes that occur during the postlactational period may serve to prepare and protect the maternal skeleton for subsequent reproductive cycles.

No effect of APD (amino hydroxypropylidene bisphosphonate) on hypercalcemia in patients with renal osteodystrophy

Hypercalcemia, due to autonomous functioning of the parathyroids following long standing secondary hyperparathyroidism, is a well known complication in patients with renal osteodystrophy, which can on most cases be treated by parathyroidectomy only. While patients with renal osteodystrophy react favorably to supplementation of active vitamin D metabolites to prevent or reverse renal osteodystrophy, the use of these drugs is bound to result in greater hypercalcemia in those patients who are already hypercalcemic. The question rose if the bisphosphonate amino hydroxypropylidene bisphosphonate (APD) would decrease plasma calcium concentration sufficiently in order to create room for the use of vitamin D to cure the osteomalacia component of the osteodystrophy and simultaneously block the excessive bone resorption. Therefore, five patients with renal osteodystrophy and hypercalcemia were treated for up to 9 months with APD. Three of them, who were on chronic hemodialysis, received 15 mg APD i.v. 3 times a week, the 2 other patients with severe renal failure received 200 mg APD orally. Ionized calcium in plasma did not decrease. Histological investigation of bone samples, obtained before and after therapy, showed an increase of fibrous tissue and a remarkable increase in the number of osteoclasts or osteoclast-like cells not only along the bone-margin, but mainly within the bone-marrow. We conclude that in patients with renal failure with hypercalcemia, APD in the doses used had no effect on plasma calcium level, but caused a striking change in bone histology. Although the consequences of these findings are not yet clear, they do not seem to indicate improvement of bone structure.