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Hall DB, Kostyla CH, Hales LM, Soliman TM. Preclinical development of EXT608, an investigational parathyroid hormone derivative with extended half-life for the treatment of hypoparathyroidism. JBMR Plus 2024; 8:ziae045. [PMID: 38721043 PMCID: PMC11078046 DOI: 10.1093/jbmrpl/ziae045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 03/04/2024] [Accepted: 03/08/2024] [Indexed: 05/12/2024] Open
Abstract
Hypoparathyroidism, a deficiency of parathyroid hormone (PTH), results in hypocalcemia, hyperphosphatemia, and hypercalciuria. The disease is poorly controlled by calcium and vitamin D supplements or native PTH(1-84) replacement therapy. A version of PTH is being developed using D-VITylation technology, whereby vitamin D is conjugated to a therapeutic peptide, which confers a long plasma half-life by virtue of binding to the abundant vitamin D binding protein (DBP). D-VITylation of PTH caused no reduction in activity at the PTHR1 receptor, and resulted in a plasma elimination half-life of 7-15 h in rats and 24-32 h in cynomolgus monkeys. Analysis of steady-state pharmacokinetics as a function of dose showed flat profiles with smaller peak:trough ratios at low doses, indicative of slower subcutaneous absorption. In thyroparathyroidectomized (TPTx) rats, PTH(1-34)-vitamin D conjugates restored serum calcium and phosphate levels into the normal range over the 24 h dosing period, and increased bone turnover markers and reduced bone mineral density. Urinary calcium was initially elevated, but normalized by the end of treatment on day 27. In healthy monkeys, a single dose of PTH(1-34)-vitamin D conjugates elevated serum calcium levels above the normal range for a period of 24-48 h while simultaneously reducing urinary calcium. Therefore, the lead compound, EXT608, is a promising candidate as a therapeutic that can truly mimic the endogenous activity of PTH and warrants further study in patients with hypoparathyroidism.
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Affiliation(s)
- Daniel B Hall
- Extend Biosciences, Inc., Newton, MA 02458, United States
| | - Caroline H Kostyla
- Extend Biosciences, Inc., Newton, MA 02458, United States
- Present address: Atalanta Therapeutics, 51 Sleeper St. Boston, MA 02210, United States
| | - Laura M Hales
- Extend Biosciences, Inc., Newton, MA 02458, United States
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Dettori C, Ronca F, Di Buono G, Saba A, Di Lupo F, Polini B, Ricardi C, Frascarelli S, Cetani F, Marcocci C, Zucchi R, Chiellini G, Scalese M, Saponaro F. Performance in Behavioral Testing in an Animal Model of Post-Surgical Hypoparathyroidism. J Pers Med 2024; 14:215. [PMID: 38392648 PMCID: PMC10890136 DOI: 10.3390/jpm14020215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/27/2024] [Accepted: 02/13/2024] [Indexed: 02/24/2024] Open
Abstract
BACKGROUND Hypoparathyroidism (HypoPT) is characterized by hypocalcemia and undetectable/inappropriately low PTH. Post-surgical HypoPT (PS-HypoPT) is the most common cause. Patients with PS-HypoPT present neuropsychological symptoms, probably due to the PTH deprivation in the central nervous system (CNS). However, these mechanisms are still not elucidated. The aim of this study was to evaluate the effects of PTH deprivation on CNS in an animal model of PS-HypoPT via a cognitive/behavioral assessment approach. METHODS A surgical rat model of PS-HypoPT was obtained and treated with calcium to maintain normocalcemia. Twenty PS-HypoPT rats and twenty sham-operated controls (Crl) underwent behavioral testing in a Morris Water Maze (MWM), Open Field (OF), and Elevated Plus Maze (EPM). RESULTS In the MWM, PTx rats showed a higher Escape Latency Time compared to Crl rats (p < 0.05); we observed a statistically significant improvement in the performance (day 1 to 8 p < 0.001), which was less pronounced in PTx group. In the OF test, the time and distance spent in the zone of interest were significantly lower in the PTx group compared with the Crl (p < 0.01 and p < 0.01). In the EPM experiment, the time spent in the close arm was significantly higher in the PTx group compared with the Crl (p < 0.01). CONCLUSIONS This animal model of PS-HypoPT shows an impairment in spatial memory, which improved after training, and a marked anxiety-like behavior, resembling the condition of patients with PS-HypoPT. Further studies are needed to elucidate mechanisms.
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Affiliation(s)
- Cristina Dettori
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
| | - Francesca Ronca
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
| | - Giulia Di Buono
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
| | - Alessandro Saba
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
| | - Francesca Di Lupo
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
| | - Beatrice Polini
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
| | - Caterina Ricardi
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
| | - Sabina Frascarelli
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
| | - Filomena Cetani
- Endocrine Unit, University Hospital of Pisa, 56124 Pisa, Italy
| | | | - Riccardo Zucchi
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
| | - Grazia Chiellini
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
| | - Marco Scalese
- Institute of Clinical Physiology, National Council of Research, 56126 Pisa, Italy
| | - Federica Saponaro
- Department of Surgical, Medical and Molecular Pathology and Critical Care, 56126 Pisa, Italy
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Peña KA, Savransky S, Lewis B. Endosomal signaling via cAMP in parathyroid hormone (PTH) type 1 receptor biology. Mol Cell Endocrinol 2024; 581:112107. [PMID: 37981188 DOI: 10.1016/j.mce.2023.112107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 10/25/2023] [Accepted: 11/06/2023] [Indexed: 11/21/2023]
Abstract
Compartmentalization of GPCR signaling is an emerging topic that highlights the physiological relevance of spatial bias in signaling. The parathyroid hormone (PTH) type 1 receptor (PTH1R) was the first GPCR described to signal via heterotrimeric G-protein and cAMP from endosomes after β-arrestin mediated internalization, challenging the canonical GPCR signaling model which established that signaling is terminated by receptor internalization. More than a decade later, many other GPCRs have been shown to signal from endosomes via cAMP, and recent studies have proposed that location of cAMP generation impacts physiological outcomes of GPCR signaling. Here, we review the extensive literature regarding PTH1R endosomal signaling via cAMP, the mechanisms that regulate endosomal generation of cAMP, and the implications of spatial bias in PTH1R physiological functions.
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Affiliation(s)
- Karina A Peña
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
| | - Sofya Savransky
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Graduate Program in Molecular Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Breanna Lewis
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Vilardaga JP, Clark LJ, White AD, Sutkeviciute I, Lee JY, Bahar I. Molecular Mechanisms of PTH/PTHrP Class B GPCR Signaling and Pharmacological Implications. Endocr Rev 2023; 44:474-491. [PMID: 36503956 PMCID: PMC10461325 DOI: 10.1210/endrev/bnac032] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 11/14/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
The classical paradigm of G protein-coupled receptor (GPCR) signaling via G proteins is grounded in a view that downstream responses are relatively transient and confined to the cell surface, but this notion has been revised in recent years following the identification of several receptors that engage in sustained signaling responses from subcellular compartments following internalization of the ligand-receptor complex. This phenomenon was initially discovered for the parathyroid hormone (PTH) type 1 receptor (PTH1R), a vital GPCR for maintaining normal calcium and phosphate levels in the body with the paradoxical ability to build or break down bone in response to PTH binding. The diverse biological processes regulated by this receptor are thought to depend on its capacity to mediate diverse modes of cyclic adenosine monophosphate (cAMP) signaling. These include transient signaling at the plasma membrane and sustained signaling from internalized PTH1R within early endosomes mediated by PTH. Here we discuss recent structural, cell signaling, and in vivo studies that unveil potential pharmacological outputs of the spatial versus temporal dimension of PTH1R signaling via cAMP. Notably, the combination of molecular dynamics simulations and elastic network model-based methods revealed how precise modulation of PTH signaling responses is achieved through structure-encoded allosteric coupling within the receptor and between the peptide hormone binding site and the G protein coupling interface. The implications of recent findings are now being explored for addressing key questions on how location bias in receptor signaling contributes to pharmacological functions, and how to drug a difficult target such as the PTH1R toward discovering nonpeptidic small molecule candidates for the treatment of metabolic bone and mineral diseases.
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Affiliation(s)
- Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Lisa J Clark
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Alex D White
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Ieva Sutkeviciute
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Ji Young Lee
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Ivet Bahar
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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Watts NB, Bilezikian JP, Bone HG, Clarke BL, Denham D, Levine MA, Mannstadt M, Peacock M, Rothman JG, Vokes TJ, Warren ML, Yin S, Sherry N, Shoback DM. Long-Term Safety and Efficacy of Recombinant Human Parathyroid Hormone (1-84) in Adults With Chronic Hypoparathyroidism. J Endocr Soc 2023; 7:bvad043. [PMID: 37091306 PMCID: PMC10119703 DOI: 10.1210/jendso/bvad043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Indexed: 04/07/2023] Open
Abstract
Context Chronic hypoparathyroidism is conventionally treated with oral calcium and active vitamin D to reach and maintain targeted serum calcium and phosphorus levels, but some patients remain inadequately controlled. Objective To assess long-term safety and efficacy of recombinant human parathyroid hormone (1-84) (rhPTH(1-84)) treatment. Methods This was an open-label extension study at 12 US centers. Adults (n = 49) with chronic hypoparathyroidism were included. The intervention was rhPTH(1-84) for 6 years. The main outcome measures were safety, biochemical measures, oral supplement doses, bone indices. Results Thirty-eight patients (77.6%) completed the study. Throughout 72 months, mean albumin-adjusted serum calcium was within 2.00 to 2.25 mmol/L (8.0-9.0 mg/dL). At baseline, 65% of patients with measurements (n = 24/37) were hypercalciuric; of these, 54% (n = 13/24) were normocalciuric at month 72. Mean serum phosphorus declined from 1.6 ± 0.19 mmol/L at baseline (n = 49) to 1.3 ± 0.20 mmol/L at month 72 (n = 36). Mean estimated glomerular filtration rate was stable. rhPTH(1-84)-related adverse events were reported in 51.0% of patients (n = 25/49); all but 1 event were mild/moderate in severity. Mean oral calcium supplementation reduced by 45% ± 113.6% and calcitriol by 74% ± 39.3%. Bone turnover markers declined by month 32 to a plateau above pretreatment values; only aminoterminal propeptide of type 1 collagen remained outside the reference range. Mean bone mineral density z score fell at one-third radius and was stable at other sites. Conclusion 6 years of rhPTH(1-84) treatment was associated with sustained improvements in biochemical parameters, a reduction in the percentage of patients with hypercalciuria, stable renal function, and decreased supplement requirements. rhPTH(1-84) was well tolerated; no new safety signals were identified.
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Affiliation(s)
- Nelson B Watts
- Osteoporosis and Bone Health Services, Mercy Health, Cincinnati, OH 45236, USA
| | - John P Bilezikian
- Division of Endocrinology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Henry G Bone
- Michigan Bone and Mineral Clinic, PC, Detroit, MI 48236, USA
| | - Bart L Clarke
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN 55905, USA
| | - Douglas Denham
- Clinical Trials of Texas, Inc., San Antonio, TX 78229, USA
| | - Michael A Levine
- Division of Endocrinology and Diabetes and Center for Bone Health, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Michael Mannstadt
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Munro Peacock
- Department of Medicine, Division of Endocrinology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | | | - Tamara J Vokes
- Section of Endocrinology, University of Chicago Medicine, Chicago, IL 60637, USA
| | - Mark L Warren
- Endocrinology and Metabolism, Physicians East, PA, Greenville, NC 27834, USA
| | - Shaoming Yin
- Takeda Pharmaceuticals USA, Inc., Lexington, MA 02421, USA
| | - Nicole Sherry
- Takeda Pharmaceuticals USA, Inc., Lexington, MA 02421, USA
| | - Dolores M Shoback
- Endocrine Research Unit, San Francisco Veterans Affairs Medical Center, San Francisco, CA 94121, USA
- Department of Medicine, University of California, San Francisco, CA 94143, USA
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Saponaro F, Alfi G, Cetani F, Matrone A, Mazoni L, Apicella M, Pardi E, Borsari S, Laurino M, Lai E, Gemignani A, Marcocci C. Serum calcium levels are associated with cognitive function in hypoparathyroidism: a neuropsychological and biochemical study in an Italian cohort of patients with chronic post-surgical hypoparathyroidism. J Endocrinol Invest 2022; 45:1909-1918. [PMID: 35751804 PMCID: PMC9463210 DOI: 10.1007/s40618-022-01822-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 05/06/2022] [Indexed: 11/14/2022]
Abstract
PURPOSE Hypoparathyroidism (HypoPT) is a rare endocrine disease and conventional therapy is based on calcium and vitamin D analogues. Conventional therapy does not restore calcium homeostasis and patients complain with neuropsychological symptoms, which have been evaluated with nonspecific self-administered questionnaires. This study aims to evaluate cognitive functions of patients with chronic post-surgical (PS)-HypoPT compared to a control population, using a standardized neuropsychological approach and evaluating the relationship with serum calcium (Alb-Ca). METHODS Observational, monocentric study on 33 patients with PS-HypoPT and 24 controls, in whom biochemical testing and a standardized neuropsychological assessment by a trained psychologist were performed. RESULTS In patients with PS-HypoPT, low Alb-Ca correlated with a worse performance on semantic memory abilities and executive function, as suggested by a significant inverse correlation between Alb-Ca and Trail Making Test A (TMT-A) scores (r = - 0.423; p = 0.014) and by a positive correlation with Semantic Fluency Test scores (SF)(r = 0.510; p = 0.002). PS-HypoPT patients with Alb-Ca ≤ 8.9 mg/dl had a significantly lower test performance compared with PS-HypoPT patients with Alb-Ca > 8.9 mg/dl, both at the TMT-A test (mean score: 34.53-18.55; p < 0.0001) and at SF test (mean score: 41.94-48.68; p = 0.01) and also a significantly lower test performance compared with control patients' group at TMT-A (mean score: 34.53-25.5; p = 0.0057). CONCLUSIONS Patients with chronic PS-HypoPT in conventional therapy do not show a severe cognitive impairment; however, cognitive functions namely visuo-spatial attention, executive function and semantic memory appear to be modulated by Alb-Ca and impaired by its low levels.
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Affiliation(s)
- F Saponaro
- Department of Surgical, Medical, and Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy.
| | - G Alfi
- Department of Surgical, Medical, and Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - F Cetani
- University Hospital of Pisa, Endocrine Unit 2, Pisa, Italy
| | - A Matrone
- University Hospital of Pisa, Endocrine Unit 2, Pisa, Italy
| | - L Mazoni
- University Hospital of Pisa, Endocrine Unit 2, Pisa, Italy
| | - M Apicella
- University Hospital of Pisa, Endocrine Unit 2, Pisa, Italy
| | - E Pardi
- University Hospital of Pisa, Endocrine Unit 2, Pisa, Italy
| | - S Borsari
- University Hospital of Pisa, Endocrine Unit 2, Pisa, Italy
| | - M Laurino
- Department of Surgical, Medical, and Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - E Lai
- Department of Surgical, Medical, and Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - A Gemignani
- Department of Surgical, Medical, and Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - C Marcocci
- University Hospital of Pisa, Endocrine Unit 2, Pisa, Italy
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
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Autoimmune polyglandular syndrome type 1 and eye damage. ACTA BIOMEDICA SCIENTIFICA 2021. [DOI: 10.29413/abs.2021-6.6-1.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Autoimmune polyendocrine syndrome type 1 (APS type 1) is a disease characterized by a variety of clinical manifestations resulting from the involvement of multiple endocrine and non-endocrine organs in the pathological process. APS type 1 is a rare genetically determined disease with autosomal recessive inheritance. Mutations in the autoimmune regulator gene (AIRE) lead to a disruption of the mechanism of normal antigen expression and the formation of abnormal clones of immune cells, and can cause autoimmune damage to organs. Within APS type 1, the most common disorders are primary adrenal insufficiency, hypoparathyroidism, and chronic candidiasis. Some understudied clinical manifestations of APS type 1 are autoimmune pathological processes in the eye: keratoconjunctivitis, dry eye syndrome, iridocyclitis, retinopathy, retinal detachment, and optic atrophy. This review presents the accumulated experimental and clinical data on the development of eye damage of autoimmune nature in APS type 1, as well as the laboratory and instrumental methods used for diagnosing the disease. Changes in the visual organs in combination with clinical manifestations of hypoparathyroidism, adrenal insufficiency and candidiasis should lead the clinical doctor to suspect the presence of APS type 1 and to examine the patient comprehensively. Timely genetic counselling will allow early identifi cation of the disease, timely prescription of appropriate treatment and prevention of severe complications.
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Goncu B, Salepcioglu Kaya H, Yucesan E, Ersoy YE, Akcakaya A. Graft survival effect of HLA-A allele matching parathyroid allotransplantation. J Investig Med 2020; 69:785-788. [PMID: 33443056 DOI: 10.1136/jim-2020-001648] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2020] [Indexed: 11/04/2022]
Abstract
Permanent hypoparathyroidism is an endocrine disease that is mostly associated with the disruption of the parathyroid glands during surgery. Allotransplantation is the most promising approach for treatment particularly for its cost-effective and exact curative potential. Herein our aim was to evaluate human leukocyte antigen (HLA)-A allele matching effect on clinical improvement and graft survival after parathyroid transplantation. We performed parathyroid transplantation between ABO/Rh compatible recipient and an unrelated donor who has chronic kidney disease. Preoperative immunological tests include panel reactive antibody, T-flow cytometry crossmatch, B-flow cytometry crossmatch, autoflow cytometry crossmatch, and complement-dependent cytotoxicity crossmatch tests were performed. After histopathological evaluation, half of the resected parathyroid gland cells were isolated and transplanted to the omentum surface by laparoscopy. The transplantation outcome was followed up throughout 382 days. The recipient discharged 2 days after transplantation without any complication. During follow-up, calcium and vitamin D supplementation reduced to a one-third dose; even the intact PTH levels remained low. However, clinical improvement was observed by serum calcium levels. The recipient still continues with low-dose supplementation after 382 days of post-transplantation. Parathyroid cell transplantation to the omental tissue is the most promising option even with only one allele matching for patients with using lifelong high-dose supplementation. Clinical improvements and long-term effect of HLA-A allele matching should be evaluated with more studies and in larger cohorts as well.
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Affiliation(s)
- Beyza Goncu
- Experimental Research Center, Bezmialem Vakif University, Istanbul, Turkey .,Parathyroid Transplantation Laboratory, Bezmialem Vakif University, Istanbul, Turkey
| | - Harika Salepcioglu Kaya
- Faculty of Medicine, Department of General Surgery, Bezmialem Vakif University, Istanbul, Turkey
| | - Emrah Yucesan
- Faculty of Medicine, Department of Medical Biology, Bezmialem Vakif University, Istanbul, Turkey
| | - Yeliz Emine Ersoy
- Faculty of Medicine, Department of General Surgery, Bezmialem Vakif University, Istanbul, Turkey.,Parathyroid Transplantation Laboratory, Bezmialem Vakif University, Istanbul, Turkey
| | - Adem Akcakaya
- Faculty of Medicine, Department of General Surgery, Bezmialem Vakif University, Istanbul, Turkey.,Organ Transplantation Unit, Bezmialem Vakif University, Istanbul, Turkey
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