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Experimental Biology and Medicine... Nov 2022Delivering the parathyroid hormone (PTH) gene has been attempted preclinically in a handful of studies, but delivering full-length PTH (1-84) using adeno-associated...
Delivering the parathyroid hormone (PTH) gene has been attempted preclinically in a handful of studies, but delivering full-length PTH (1-84) using adeno-associated viral (AAV) vectors has not. Given the difficulty in achieving therapeutic levels of secreted proteins using gene therapy, this study seeks to determine the feasibility of doing so with PTH. An AAV vector was used to deliver human PTH driven by a strong promoter. We demonstrate the ability to secrete full-length PTH from various cell types . PTH secretion from hepatocytes was measured over time and a fluorescent marker was used to compare the secretion rate of PTH in various cell types. Potency was measured by the ability of PTH to act on the PTH receptors of osteosarcoma cells and induced proliferation. PTH showed potency by inducing proliferation in two osteosarcoma cell lines. , AAV was administered systemically in immunocompromised mice which received xenografts of osteosarcoma cells. Animals that received the highest dose of AAV-PTH had higher liver and plasma concentrations of PTH. All dosing groups achieved measurable plasma concentrations of human PTH that were above the normal range. The high-dose group also had significantly larger tumors compared to control groups on the final day of the study. The tumors also showed dose-dependent differences in morphology. When looking at endocrine signaling and endogenous bone turnover, we observed a significant difference in tibial growth plate width in animals that received the high-dose AAV as well as dose-dependent changes in blood biomarkers related to PTH. This proof-of-concept study shows promise for further exploration of an AAV gene therapy to deliver full-length PTH for hypoparathyroidism. Additional investigation will determine efficacy in a disease model, but data shown establish bioactivity in well-established models of osteosarcoma.
Topics: Humans; Animals; Mice; Parathyroid Hormone
PubMed: 35666091
DOI: 10.1177/15353702221097087 -
Current Osteoporosis Reports Dec 2013Osteoporotic fractures result in significant morbidity and mortality. Anabolic agents reverse the negative skeletal balance that characterizes osteoporosis by... (Review)
Review
Osteoporotic fractures result in significant morbidity and mortality. Anabolic agents reverse the negative skeletal balance that characterizes osteoporosis by stimulating osteoblast-dependent bone formation to a greater degree than osteoclast-dependent bone resorption. Parathyroid hormone (PTH) and parathyroid hormone- related protein (PTHrP) are peptide hormones, which have anabolic actions when administered intermittently. The only FDA-approved anabolic bone agent for the treatment of osteoporosis in the United States is PTH 1-34, or teriparatide, administered by daily subcutaneous injections. However, PTH 1-84 is also available in Europe. Synthetic human PTHrP 1-36 and a PTHrP 1-34 analog, BA058, have also been shown to increase lumbar spine bone density. These agents and several other PTH and PTHrP analogs, including some which are not administered as injections, continue to be investigated as potential anabolic therapies for osteoporosis.
Topics: Anabolic Agents; Animals; Bone Resorption; Disease Models, Animal; Humans; Osteogenesis; Osteoporosis; Parathyroid Hormone; Parathyroid Hormone-Related Protein; Teriparatide; Treatment Outcome
PubMed: 24078470
DOI: 10.1007/s11914-013-0171-2 -
Journal of Bone and Mineral Research :... Dec 2022The approach utilized a systematic review of the medical literature executed with specifically designed criteria that focused on the etiologies and pathogenesis of...
The approach utilized a systematic review of the medical literature executed with specifically designed criteria that focused on the etiologies and pathogenesis of hypoparathyroidism. Enhanced attention by endocrine surgeons to new knowledge about parathyroid gland viability are reviewed along with the role of intraoperative parathyroid hormone (ioPTH) monitoring during and after neck surgery. Nonsurgical etiologies account for a significant proportion of cases of hypoparathyroidism (~25%), and among them, genetic etiologies are key. Given the pervasive nature of PTH deficiency across multiple organ systems, a detailed review of the skeletal, renal, neuromuscular, and ocular complications is provided. The burden of illness on affected patients and their caregivers contributes to reduced quality of life and social costs for this chronic endocrinopathy. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
Topics: Humans; Hypoparathyroidism; Parathyroid Hormone; Quality of Life; Parathyroid Glands
PubMed: 36153665
DOI: 10.1002/jbmr.4714 -
Journal of Orthopaedic Research :... Oct 2018Delayed healing and/or non-union occur in approximately 5-10% of the fractures that occur annually in the United States. Segmental bone loss increases the probability of... (Review)
Review
Delayed healing and/or non-union occur in approximately 5-10% of the fractures that occur annually in the United States. Segmental bone loss increases the probability of non-union. Though grafting can be an effective treatment for segmental bone loss, autografting is limited for large defects since a limited amount of bone is available for harvest. Parathyroid hormone (PTH) is a key regulator of calcium homeostasis in the body and plays an important role in bone metabolism. Presently PTH is FDA approved for use as an anabolic treatment for osteoporosis. The anabolic effect PTH has on bone has led to research on its use for bone regeneration applications. Numerous studies in animal models have indicated enhanced fracture healing as a result of once daily injections of PTH. Similarly, in a human case study, non-union persisted despite treatment attempts with internal fixation, external fixation, and autograft in combination with BMP-7, until off label use of PTH1-84 was utilized. Use of a biomaterial scaffold to locally deliver PTH to a defect site has also been shown to improve bone formation and healing around dental implants in dogs and drill defects in sheep. Thus, PTH may be used to promote bone regeneration and provide an alternative to autograft and BMP for the treatment of large segmental defects and non-unions. This review briefly summarizes the unmet clinical need for improved bone regeneration techniques and how PTH may help fill that void by both systemically and locally delivered PTH for bone regeneration applications. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2586-2594, 2018.
Topics: Bone Regeneration; Fractures, Ununited; Humans; Parathyroid Hormone
PubMed: 29926970
DOI: 10.1002/jor.24075 -
Journal of Bone and Mineral Research :... Jun 2021The standard treatment of primary hypoparathyroidism (hypoPT) with oral calcium supplementation and calcitriol (or an analog), intended to control hypocalcemia and... (Clinical Trial)
Clinical Trial
The standard treatment of primary hypoparathyroidism (hypoPT) with oral calcium supplementation and calcitriol (or an analog), intended to control hypocalcemia and hyperphosphatemia and avoid hypercalciuria, remains challenging for both patients and clinicians. In 2015, human parathyroid hormone (hPTH) (1-84) administered as a daily subcutaneous injection was approved as an adjunctive treatment in patients who cannot be well controlled on the standard treatments alone. This open-label study aimed to assess the safety and efficacy of an oral hPTH(1-34) formulation as an adjunct to standard treatment in adult subjects with hypoparathyroidism. Oral hPTH(1-34) tablets (0.75 mg human hPTH(1-34) acetate) were administered four times daily for 16 consecutive weeks, and changes in calcium supplementation and alfacalcidol use, albumin-adjusted serum calcium (ACa), serum phosphate, urinary calcium excretion, and quality of life throughout the study were monitored. Of the 19 enrolled subjects, 15 completed the trial per protocol. A median 42% reduction from baseline in exogenous calcium dose was recorded (p = .001), whereas median serum ACa levels remained above the lower target ACa levels for hypoPT patients (>7.5 mg/dL) throughout the study. Median serum phosphate levels rapidly decreased (23%, p = .0003) 2 hours after the first dose and were maintained within the normal range for the duration of the study. A notable, but not statistically significant, median decrease (21%, p = .07) in 24-hour urine calcium excretion was observed between the first and last treatment days. Only four possible drug-related, non-serious adverse events were reported over the 16-week study, all by the same patient. A small but statistically significant increase from baseline quality of life (5%, p = .03) was reported by the end of the treatment period. Oral hPTH(1-34) treatment was generally safe and well tolerated and allowed for a reduction in exogenous calcium supplementation, while maintaining normocalcemia in adult patients with hypoparathyroidism. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
Topics: Adult; Calcitriol; Calcium; Humans; Hypoparathyroidism; Parathyroid Hormone; Quality of Life; Teriparatide
PubMed: 33666947
DOI: 10.1002/jbmr.4274 -
Endocrinology and Metabolism Clinics of... Dec 2018The parathyroid glands are essential for regulating calcium homeostasis in the body. The genetic programs that control parathyroid fate specification, morphogenesis,... (Review)
Review
The parathyroid glands are essential for regulating calcium homeostasis in the body. The genetic programs that control parathyroid fate specification, morphogenesis, differentiation, and survival are only beginning to be delineated, but are all centered around a key transcription factor, GCM2. Mutations in the Gcm2 gene as well as in several other genes involved in parathyroid organogenesis have been found to cause parathyroid disorders in humans. Therefore, understanding the normal development of the parathyroid will provide insight into the origins of parathyroid disorders.
Topics: Animals; Gene Expression Regulation; Humans; Nuclear Proteins; Parathyroid Glands; Parathyroid Hormone; Transcription Factors
PubMed: 30390809
DOI: 10.1016/j.ecl.2018.07.002 -
Physiological Reviews Jul 2016Although parathyroid hormone-related protein (PTHrP) was discovered as a cancer-derived hormone, it has been revealed as an important paracrine/autocrine regulator in... (Review)
Review
Although parathyroid hormone-related protein (PTHrP) was discovered as a cancer-derived hormone, it has been revealed as an important paracrine/autocrine regulator in many tissues, where its effects are context dependent. Thus its location and action in the vasculature explained decades-long observations that injection of PTH into animals rapidly lowered blood pressure by producing vasodilatation. Its roles have been specified in development and maturity in cartilage and bone as a crucial regulator of endochondral bone formation and bone remodeling, respectively. Although it shares actions with parathyroid hormone (PTH) through the use of their common receptor, PTHR1, PTHrP has other actions mediated by regions within the molecule beyond the amino-terminal sequence that resembles PTH, including the ability to promote placental transfer of calcium from mother to fetus. A striking feature of the physiology of PTHrP is that it possesses structural features that equip it to be transported in and out of the nucleus, and makes use of a specific nuclear import mechanism to do so. Evidence from mouse genetic experiments shows that PTHrP generated locally in bone is essential for normal bone remodeling. Whereas the main physiological function of PTH is the hormonal regulation of calcium metabolism, locally generated PTHrP is the important physiological mediator of bone remodeling postnatally. Thus the use of intermittent injection of PTH as an anabolic therapy for bone appears to be a pharmacological application of the physiological function of PTHrP. There is much current interest in the possibility of developing PTHrP analogs that might enhance the therapeutic anabolic effects.
Topics: Animals; Bone Development; Bone Diseases; Cartilage; Humans; Mice; Parathyroid Hormone; Parathyroid Hormone-Related Protein
PubMed: 27142453
DOI: 10.1152/physrev.00031.2015 -
Endocrinology and Metabolism Clinics of... Dec 2018Hypoparathyroidism is characterized by hypocalcemia and hyperphosphatemia and is due to insufficient levels of circulating parathyroid hormone. Hypoparathyroidism may be... (Review)
Review
Hypoparathyroidism is characterized by hypocalcemia and hyperphosphatemia and is due to insufficient levels of circulating parathyroid hormone. Hypoparathyroidism may be an isolated condition or a component of a complex syndrome. Although genetic disorders are not the most common cause of hypoparathyroidism, molecular analyses have identified a growing number of genes that when defective result in impaired formation of the parathyroid glands, disordered synthesis or secretion of parathyroid hormone, or postnatal destruction of the parathyroid glands.
Topics: Humans; Hypoparathyroidism; Parathyroid Diseases; Parathyroid Glands; Parathyroid Hormone
PubMed: 30390815
DOI: 10.1016/j.ecl.2018.07.007 -
Molecular basis of parathyroid hormone receptor signaling and trafficking: a family B GPCR paradigm.Cellular and Molecular Life Sciences :... Jan 2011The parathyroid hormone (PTH) receptor type 1 (PTHR), a G protein-coupled receptor (GPCR), transmits signals to two hormone systems-PTH, endocrine and homeostatic, and... (Review)
Review
The parathyroid hormone (PTH) receptor type 1 (PTHR), a G protein-coupled receptor (GPCR), transmits signals to two hormone systems-PTH, endocrine and homeostatic, and PTH-related peptide (PTHrP), paracrine-to regulate different biological processes. PTHR responds to these hormonal stimuli by activating heterotrimeric G proteins, such as G(S) that stimulates cAMP production. It was thought that the PTHR, as for all other GPCRs, is only active and signals through G proteins on the cell membrane, and internalizes into a cell to be desensitized and eventually degraded or recycled. Recent studies with cultured cell and animal models reveal a new pathway that involves sustained cAMP signaling from intracellular domains. Not only do these studies challenge the paradigm that cAMP production triggered by activated GPCRs originates exclusively at the cell membrane but they also advance a comprehensive model to account for the functional differences between PTH and PTHrP acting through the same receptor.
Topics: Animals; Cell Membrane; Cyclic AMP; GTP-Binding Proteins; Humans; Models, Biological; Parathyroid Hormone; Parathyroid Hormone-Related Protein; Protein Structure, Tertiary; Receptor, Parathyroid Hormone, Type 1; Signal Transduction; Structure-Activity Relationship
PubMed: 20703892
DOI: 10.1007/s00018-010-0465-9 -
British Journal of Clinical Pharmacology Feb 2018In primary hyperparathyroidism (PHPT), bone loss results from the resorptive effects of excess parathyroid hormone (PTH). Under physiological conditions, PTH has actions... (Review)
Review
In primary hyperparathyroidism (PHPT), bone loss results from the resorptive effects of excess parathyroid hormone (PTH). Under physiological conditions, PTH has actions that are more targeted to homeostasis and to bone accrual. The predominant action of PTH, either catabolic, anabolic or homeostatic, can be understood in molecular and pharmacokinetic terms. When administered intermittently, PTH increases bone mass, but when present continuously and in excess (e.g. PHPT), bone loss ensues. This dual effect of PTH depends not only on the dosing regimen, continuous or intermittent, but also on how the PTH molecule interacts with various states of its receptor (PTH/PTHrP receptor) influencing downstream signalling pathways differentially. Altering the amino-terminal end of PTH or PTHrP could emphasize the state of the receptor that is linked to an osteoanabolic outcome. This concept led to the development of a PTHrP analogue that interacts preferentially with the transiently linked state of the receptor, emphasizing an osteoanabolic effect. However, designing PTH or PTHrP analogues with prolonged state of binding to the receptor would be expected to be linked to a homeostatic action associated with the tonic secretory state of the parathyroid glands that is advantageous in treating hypoparathyroidism. Ideally, further development of a drug delivery system that mimics the physiological tonic, circadian, and pulsatile profile of PTH would be optimal. This review discusses basic, translational and clinical studies that may well lead to newer approaches to the treatment of osteoporosis as well as to different PTH molecules that could become more advantageous in treating hypoparathyroidism.
Topics: Bone Density; Bone and Bones; Dose-Response Relationship, Drug; Drug Delivery Systems; Homeostasis; Humans; Hypoparathyroidism; Osteoporosis; Parathyroid Hormone; Protein Binding; Receptor, Parathyroid Hormone, Type 1; Translational Research, Biomedical
PubMed: 29049872
DOI: 10.1111/bcp.13455