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Hsu S, Bansal N, Denburg M, Ginsberg C, Hoofnagle AN, Isakova T, Ix JH, Robinson-Cohen C, Wolf M, Kestenbaum BR, de Boer IH, Zelnick LR. Risk factors for hip and vertebral fractures in chronic kidney disease: the CRIC study. J Bone Miner Res 2024; 39:433-442. [PMID: 38477777 PMCID: PMC11262146 DOI: 10.1093/jbmr/zjae021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/19/2024] [Accepted: 01/25/2024] [Indexed: 03/14/2024]
Abstract
Fracture risk is high in chronic kidney disease (CKD) and underlying pathophysiology and risk factors may differ from the general population. In a cohort study of 3939 participants in the chronic renal insufficiency cohort (CRIC), we used Cox regression to test associations of putative risk factors with the composite of first hip or vertebral fracture assessed using hospital discharge codes. Mean age was 58 years, 45% were female, 42% were Black, and 13% were Hispanic. There were 82 hip and 24 vertebral fractures over a mean (SD) 11.1 (4.8) years (2.4 events per 1000 person-years [95% CI: 2.0, 2.9]). Measured at baseline, diabetes, lower body mass index (BMI), steroid use, proteinuria, and elevated parathyroid hormone (PTH) were each associated with fracture risk after adjusting for covariates. Lower time-updated estimated glomerular filtration rate (eGFR) was associated with fractures (HR 1.20 per 10 mL/min/1.73m2 lower eGFR; 95% CI: 1.04, 1.38) as were lower time-updated serum calcium and bicarbonate concentrations. Among time-updated categories of kidney function, hazard ratios (95% CI) for incident fracture were 4.53 (1.77, 11.60) for kidney failure treated with dialysis and 2.48 (0.86, 7.14) for post-kidney transplantation, compared with eGFR ≥60. Proton pump inhibitor use, dietary calcium intake, measures of vitamin D status, serum phosphate, urine calcium and phosphate, and plasma fibroblast growth factor-23 were not associated with fracture risk. In conclusion, lower eGFR in CKD is associated with higher fracture risk, which was highest in kidney failure. Diabetes, lower BMI, steroid use, proteinuria, higher serum concentrations of PTH, and lower calcium and bicarbonate concentrations were associated with fractures and may be modifiable risk factors.
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Affiliation(s)
- Simon Hsu
- Division of Nephrology and Kidney Research Institute, Department of Medicine, University of Washington, Seattle, WA 98195, United States
| | - Nisha Bansal
- Division of Nephrology and Kidney Research Institute, Department of Medicine, University of Washington, Seattle, WA 98195, United States
| | - Michelle Denburg
- Division of Nephrology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
- Departments of Pediatrics and Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Charles Ginsberg
- Division of Nephrology-Hypertension, University of California, San Diego, San Diego, CA 92103, United States
| | - Andrew N Hoofnagle
- Department of Laboratory Medicine, University of Washington, Seattle, WA 98195, United States
| | - Tamara Isakova
- Division of Nephrology and Hypertension, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States
| | - Joachim H Ix
- Division of Nephrology-Hypertension, University of California, San Diego, San Diego, CA 92103, United States
| | - Cassianne Robinson-Cohen
- Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN 37232, United States
| | - Myles Wolf
- Division of Nephrology, Department of Medicine, Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC 27710, United States
| | - Bryan R Kestenbaum
- Division of Nephrology and Kidney Research Institute, Department of Medicine, University of Washington, Seattle, WA 98195, United States
| | - Ian H de Boer
- Division of Nephrology and Kidney Research Institute, Department of Medicine, University of Washington, Seattle, WA 98195, United States
| | - Leila R Zelnick
- Division of Nephrology and Kidney Research Institute, Department of Medicine, University of Washington, Seattle, WA 98195, United States
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Easson M, Wong S, Moody M, Schmidt TA, Deymier A. Physiochemical effects of acid exposure on bone composition and function. J Mech Behav Biomed Mater 2024; 150:106304. [PMID: 38096610 DOI: 10.1016/j.jmbbm.2023.106304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 10/04/2023] [Accepted: 12/02/2023] [Indexed: 01/09/2024]
Abstract
Bone is primarily composed of collagen and apatite, two materials which exhibit a high sensitivity to pH dysregulation. As a result, acid exposure of bone, both clinically and in the laboratory is expected to cause compositional and mechanical changes to the tissue. Clinically, Metabolic acidosis (MA), a condition characterized by a reduced physiological pH, has been shown to have negative implications on bone health, including a decrease in bone mineral density and volume as well as increased fracture risk. The addition of bone-like apatite to ionic solutions such as phosphate buffered saline (PBS) and media has been shown to acidify the solution leading to bone acid exposure. Therefore, is it essential to understand how reduced pH physiochemically affects bone composition and in turn its mechanical properties. This study investigates the specific changes in bone due to physiochemical dissolution in acid. Excised murine bones were placed in PBS solutions at different pHs: a homeostatic pH level (pH 7.4), an acidosis equivalent (pH 7.0), and an extreme acidic solution (pH 5.5). After 5 days, the bones were removed from the solutions and characterized to determine compositional and material changes. We found that bones, without cells, were able to regulate pH via buffering, leading to a decrease in bone mineral content and an increase in collagen denaturation. Both of these compositional changes contributed to an increase in bone toughness by creating a more ductile bone surface and preventing crack propagation. Therefore, we conclude that the skeletal systems' physiochemical response to acid exposure includes multifaceted and spatially variable compositional changes that affect bone mechanics.
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Affiliation(s)
- Margaret Easson
- Dept. of Biomedical Engineering, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT, USA
| | - Stephanie Wong
- Dept. of Biomedical Engineering, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT, USA
| | - Mikayla Moody
- Dept. of Biomedical Engineering, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT, USA
| | - Tannin A Schmidt
- Dept. of Biomedical Engineering, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT, USA
| | - Alix Deymier
- Dept. of Biomedical Engineering, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT, USA.
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3
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Nag S, De Bruyker I, Nelson A, Moody M, Fais M, Deymier AC. Acidosis induces significant changes to the murine supraspinatus enthesis organic matrix. Connect Tissue Res 2024; 65:41-52. [PMID: 37962089 DOI: 10.1080/03008207.2023.2275044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 10/13/2023] [Indexed: 11/15/2023]
Abstract
Rotator cuff pathology is a common musculoskeletal condition that disproportionately affects older adults, as well as patients with diabetes mellitus and chronic kidney disease. It is known that increased age and kidney dysfunction have been correlated to acidotic states, which may be related to the increased incidence of rotator cuff injury. In order to investigate the potential relationship between acidosis and rotator cuff composition and mechanics, this study utilizes a 14-day murine model of metabolic acidosis and examines the effects on the supraspinatus tendon-humeral head attachment complex. The elastic matrix in the enthesis exhibited significant changes beginning at day 3 of acidosis exposure. At day 3 and day 7 timepoints, there was a decrease in collagen content seen in both mineralized and unmineralized tissue as well as a decrease in mineral:matrix ratio. There is also evidence of both mineral dissolution and reprecipitation as buffering ions continually promote pH homeostasis. Mechanical properties of the tendon-to-bone attachment were studied; however, no significant changes were elicited in this 14-day model of acidosis. These findings suggest that acidosis can result in significant changes in enthesis composition over the course of 14 days; however, enthesis mechanics may be more structurally mediated rather than affected by compositional changes.
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Affiliation(s)
- Saparja Nag
- School of Medicine, University of Connecticut, Farmington, CT, USA
| | | | - Ashley Nelson
- Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - Mikayla Moody
- Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, USA
| | - Marla Fais
- Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - Alix C Deymier
- Biomedical Engineering, University of Connecticut, Storrs, CT, USA
- Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, USA
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Liu Z, Xiang L, Tian M, Wang H, Zhao X, Liu K, Yu J, Liu T, Liu S, Mu X, Yang B, Zhang S, Luo J. A Counterion-Free Strategy for Chronic Metabolic Acidosis Based on an Orally Administered Gut-Restricted Inorganic Adsorbent. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2305992. [PMID: 37921507 DOI: 10.1002/adma.202305992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 10/23/2023] [Indexed: 11/04/2023]
Abstract
Chronic metabolic acidosis, arising as a complication of chronic kidney disease (CKD), not only reduces patients' quality of life but also aggravates renal impairment. The only available therapeutic modality, involving intravenous infusion of NaHCO3 , engenders undesirable sodium retention, thereby increasing hemodynamic load and seriously exacerbating the primary disease. This deleterious cascade extends to the development of cardiovascular diseases. Herein, an orally administered, gut-restricted inorganic adsorbent that can effectively alleviate chronic metabolic acidosis without causing any electrolytic derangement or superfluous cardiovascular strain is developed. The genesis of ABC-350 entails the engineering of bismuth subcarbonate via annealing, thereby yielding a partially β-Bi2 O3 -doped (BiO)2 CO3 biphasic crystalline structure framework enriched with atomic vacancies. ABC-350 can selectively remove chloride ions and protons from the gastrointestinal tract, mimicking the physiological response to gastric acid removal and resulting in increased serum bicarbonate. Owing to its gut-restricted nature, ABC-350 exhibits commendable biosafety, averting undue systemic exposure. In two rat models of metabolic acidosis, ABC-350 emerges not only as a potent mitigator of acidosis but also effects discernible amelioration concerning proximal tubular morphology, interstitial fibrosis, and the incendiary cascades incited by metabolic acidosis. ABC-350, as the translationally relevant material, provides a promising strategy for the treatment of metabolic acidosis.
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Affiliation(s)
- Zhen Liu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Liang Xiang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Meng Tian
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Haoyu Wang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xin Zhao
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Kangfei Liu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jia Yu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Tianzhi Liu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Shangpeng Liu
- School of Materials Science and Engineering, Tongji University, Shanghai, 201384, China
| | - Xin Mu
- School of Biomedical Engineering, ShanghaiTech University, Shanghai, 201210, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Bingxue Yang
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Shiyi Zhang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jie Luo
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
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Moody M, Schmidt TA, Trivedi R, Deymier A. Administration of alendronate exacerbates ammonium chloride-induced acidosis in mice. PLoS One 2023; 18:e0291649. [PMID: 37713420 PMCID: PMC10503749 DOI: 10.1371/journal.pone.0291649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 09/04/2023] [Indexed: 09/17/2023] Open
Abstract
Bone disease is highly prevalent in patients with chronic kidney disease (CKD), leading to an increased risk of bone fractures. This is due in part to metabolic acid-induced bone dissolution. Bisphosphonates (BPPs) are a potential treatment for inhibiting bone dissolution; however, there are limited studies observing the use of BPPs on acidotic patients. We aimed to determine efficacy of BPPs on maintaining bone health and pH regulation in acid-exposed mice. Using a diet-induced murine model of metabolic acidosis, we examined bone structure, composition, and mechanics as well as blood gases for three groups: control, acidosis, and acidosis + bisphosphonates (acidosis+BPP). Acidosis was induced for 14 days and alendronate was administered every 3 days for the acidosis+BPP group. The administration of BPP had little to no effect on bone structure, mechanics, and composition of the acidosis bones. However, administration of BPP did cause the mice to develop more severe acidosis than the acidosis only group. Overall, we discovered that BPPs may exacerbate acidosis symptoms by inhibiting the release of buffering ions from bone. Therefore, we propose that BPP administration should be carefully considered for those with CKD and that alkali supplementation could help minimize acidifying effects.
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Affiliation(s)
- Mikayla Moody
- Department of Biomedical Engineering, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT, United States of America
| | - Tannin A. Schmidt
- Department of Biomedical Engineering, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT, United States of America
| | - Ruchir Trivedi
- Department of Nephrology, School of Medicine, University of Connecticut Health Center, Farmington, CT, United States of America
| | - Alix Deymier
- Department of Biomedical Engineering, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT, United States of America
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Liu Y, Atiq A, Peterson A, Moody M, Novin A, Deymier AC, Afzal J. Metabolic Acidosis Results in Sexually Dimorphic Response in the Heart Tissue. Metabolites 2023; 13:metabo13040549. [PMID: 37110207 PMCID: PMC10142987 DOI: 10.3390/metabo13040549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/07/2023] [Accepted: 04/09/2023] [Indexed: 04/29/2023] Open
Abstract
Metabolic acidosis (MA) is a highly prevalent disorder in a significant proportion of the population, resulting from imbalance in blood pH homeostasis. The heart, being an organ with very low regenerative capacity and high metabolic activity, is vulnerable to chronic, although low-grade, MA. To systematically characterize the effect of low-grade MA on the heart, we treated male and female mice with NH4Cl supplementation for 2 weeks and analyzed their blood chemistry and transcriptomic signature of the heart tissue. The reduction of pH and plasma bicarbonate levels without an associated change in anion gap indicated a physiological manifestation of low-grade MA with minimal respiratory compensation. On transcriptomic analysis, we observed changes in cardiac-specific genes with significant gender-based differences due to MA. We found many genes contributing to dilated cardiomyopathy to be altered in males, more than in females, while cardiac contractility and Na/K/ATPase-Src signaling were affected in the opposite way. Our model presents a systems-level understanding of how the cardiovascular tissue is affected by MA. As low-grade MA is a common ailment with many dietary and pharmaceutical interventions, our work presents avenues to limit chronic cardiac damage and disease manifestation, as well as highlighting the sex differences in MA-induced cardiovascular damage.
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Affiliation(s)
- Yamin Liu
- Department of Biomedical Engineering, University of Connecticut Health, Farmington, CT 06032, USA
| | - Amina Atiq
- Department of Biomedical Engineering, University of Connecticut Health, Farmington, CT 06032, USA
| | - Anna Peterson
- Department of Biomedical Engineering, University of Connecticut Health, Farmington, CT 06032, USA
| | - Mikayla Moody
- Department of Biomedical Engineering, University of Connecticut Health, Farmington, CT 06032, USA
| | - Ashkan Novin
- Department of Biomedical Engineering, University of Connecticut Health, Farmington, CT 06032, USA
| | - Alix C Deymier
- Department of Biomedical Engineering, University of Connecticut Health, Farmington, CT 06032, USA
| | - Junaid Afzal
- Division of Cardiology, Department of Medicine, University of California San Francisco, San Francisco, CA 94158, USA
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7
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Levy RV, McMahon DJ, Agarwal S, Dempster D, Zhou H, Misof BM, Guo X, Kamanda-Kosseh M, Aponte MA, Reidy K, Kumar J, Fusaro M, Brown DD, Melamed ML, Nickolas TL. Comprehensive Associations between Acidosis and the Skeleton in Patients with Kidney Disease. J Am Soc Nephrol 2023; 34:668-681. [PMID: 36749125 PMCID: PMC10103353 DOI: 10.1681/asn.0000000000000085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 01/10/2023] [Indexed: 02/08/2023] Open
Abstract
SIGNIFICANCE STATEMENT Renal osteodystrophy (ROD) contributes substantially to morbidity in CKD, including increased fracture risk. Metabolic acidosis (MA) contributes to the development of ROD, but an up-to-date skeletal phenotype in CKD-associated acidosis has not been described. We comprehensively studied associations between acidosis and bone in patients with CKD using advanced methods to image the skeleton and analyze bone-tissue, along with biochemical testing. Cross-sectionally, acidosis was associated with higher markers of bone remodeling and female-specific impairments in cortical and trabecular bone quality. Prospectively, acidosis was associated with cortical expansion and trabecular microarchitectural deterioration. At the bone-tissue level, acidosis was associated with deficits in bone mineral content. Future work investigating acidosis correction on bone quality is warranted. BACKGROUND Renal osteodystrophy is a state of impaired bone quality and strength. Metabolic acidosis (MA) is associated with alterations in bone quality including remodeling, microarchitecture, and mineralization. No studies in patients with CKD have provided a comprehensive multimodal skeletal phenotype of MA. We aim to describe the structure and makeup of bone in patients with MA in the setting of CKD using biochemistry, noninvasive imaging, and histomorphometry. METHODS The retrospective cross-sectional analyses included 180 patients with CKD. MA was defined as bicarbonate ≤22 mEq/L. We evaluated circulating bone turnover markers and skeletal imaging with dual energy x-ray absorptiometry and high-resolution peripheral computed tomography. A subset of 54 participants had follow-up. We assessed associations between baseline and change in bicarbonate with change in bone outcomes. Histomorphometry, microCT, and quantitative backscatter electron microscopy assessed bone biopsy outcomes in 22 participants. RESULTS The mean age was 68±10 years, 54% of participants were male, and 55% were White. At baseline, acidotic subjects had higher markers of bone turnover, lower areal bone mineral density at the radius by dual energy x-ray absorptiometry, and lower cortical and trabecular volumetric bone mineral density and impaired trabecular microarchitecture. Over time, acidosis was associated with opposing cortical and trabecular effects: cortical expansion but trabecular deterioration. Bone-tissue analyses showed reduced tissue mineral density with increased heterogeneity of calcium distribution in acidotic participants. CONCLUSIONS MA is associated with multiple impairments in bone quality. Future work should examine whether correction of acidosis improves bone quality and strength in patients with CKD.
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Affiliation(s)
- Rebecca V. Levy
- Nephrology, Department of Medicine, University of Rochester Medical Center Rochester, New York, USA
- Pediatric Nephrology, Department of Pediatrics, University of Rochester Medical Center, Rochester, New York, USA
| | | | | | - David Dempster
- Columbia University Irving Medical Center, New York, USA
| | - Hua Zhou
- Columbia University Irving Medical Center, New York, USA
| | - Barbara M. Misof
- Ludwig Boltzmann Institute for Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria
| | - X.E. Guo
- Columbia University Biomedical Engineering, New York, New York, USA
| | | | | | - Kimberly Reidy
- Nephrology, Department of Medicine, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, New York
| | - Juhi Kumar
- Nephrology, Department of Pediatrics, Weill-Cornell Medical Center, New York, New York
| | - Maria Fusaro
- National Research Council (CNR), Institute of Clinical Physiology (IFC), Pisa, Italy
- Department of Medicine, University of Padova, Padova, Padua, Italy
| | - Denver D. Brown
- Division of Nephrology, Children's National Hospital, Washington, DC
| | - Michal L. Melamed
- Nephrology, Department of Medicine, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, New York
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Bushinsky DA, Krieger NS. Effects of Acid on Bone. Kidney Int 2022; 101:1160-1170. [DOI: 10.1016/j.kint.2022.02.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 02/25/2022] [Accepted: 02/28/2022] [Indexed: 12/11/2022]
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Cheong VS, Roberts BC, Kadirkamanathan V, Dall'Ara E. Positive interactions of mechanical loading and PTH treatments on spatio-temporal bone remodelling. Acta Biomater 2021; 136:291-305. [PMID: 34563722 DOI: 10.1016/j.actbio.2021.09.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/03/2021] [Accepted: 09/17/2021] [Indexed: 11/26/2022]
Abstract
Osteoporosis is one of the most common skeletal diseases, but current therapies are limited to generalized antiresorptive or anabolic interventions, which do not target regions that would benefit from improvements to skeletal health. To improve the evaluation of treatment plans, we used a spatio-temporal multiscale approach that combines longitudinal in vivo micro-computed tomography (micro-CT) and in silico subject-specific finite element modeling to quantitatively map bone adaptation changes due to disease and treatment at high resolution. Our findings show time and region-dependent modifications in bone remodelling following one and two sets of mechanical loading and/or pharmacological interventions. The multiscale results highlighted that the distal section was unaffected by mechanical loading alone but the proximal tibia had the greatest gain from positive interactions of combined therapies. Mechanical loading abated the catabolic effect of PTH, but the main benefit of combined treatments occurred from the additive interactions of the two therapies in periosteal apposition. These results provide detailed insight into the efficacy of combined treatments, facilitating the optimisation of dosage and treatment duration in preclinical mouse studies, and the development of novel interventions for skeletal diseases. STATEMENT OF SIGNIFICANCE: Combined mechanical loading and pharmacotherapy have the potential to slow osteoporosis-induced bone loss but current therapies do not target the regions in need of strengthening. We show for the first time spatial region-dependant interactions between PTH and mechanical loading treatment in OVX mouse tibiae, highlighting local regions in the tibia that benefitted from separate and combined treatments. Combined experimental-computational analysis also detailed the lasting period of each treatment per location in the tibia, the extent of positive (or negative) interactions of the combined therapies, and the impact of each treatment on the regulation of bone adaptation spatio-temporally. This approach can be used to create hypothesis about the interactions of different treatments to optimise the design of biomaterials and medical interventions.
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