Allotransplantation of Cultured Parathyroid Progenitor Cells Without Immunosuppression: Clinical Results

Incidence of Post-Thyroidectomy Hypoparathyroidism and Associated Preoperative and Intraoperative Risk Factors

INTRODUCTION

Thyroidectomy technique and extent are related to parathyroid injury and hypoparathyroidism. Total thyroidectomy is one of the most commonly performed endocrine surgeries, and the majority of patients recover completely without any complications. However, persistent hypoparathyroidism is the most prevalent long-term consequence following total thyroidectomy. While it is seldom deadly, it can cause severe morbidity for the patient and raise healthcare expenses.

METHODS

This retrospective cohort study was conducted at King Abdulaziz Medical City, Jeddah, Saudi Arabia. We included all confirmed thyroid cancer cases that underwent thyroidectomy with or without neck dissection between July 2016 and August 2022. The data was collected from a chart review of the electronic medical record system (BEST-care), and a data collection sheet was utilized. SPSS version 26 was used to analyze the data.

RESULTS

A total of 192 patients undergoing thyroid surgery were enrolled. One hundred forty-three (74.5%) were females and the mean age of participants was 45.29 ± 16.88 years. Most patients, 170 (88.5%), had a papillary histological type, and total thyroidectomy was performed in 150 (78.1%). A significant association was found between the type of surgery and postoperative hypoparathyroidism (p=<0.05*). In addition, hypocalcemia was seen in 147 (76.6%) of the patients. Postoperative hypoparathyroidism was significantly higher among patients who had asymptomatic postoperative hypocalcemia and those who received IV calcium gluconate (p=<0.05*). Moreover, postoperative hypocalcemia, hypomagnesemia, and hyperphosphatemia were significantly associated with postoperative hypoparathyroidism (p=<0.05*).

CONCLUSION

The incidence of postoperative hypoparathyroidism is significantly higher among patients who underwent total thyroidectomy and had a normal level of preoperative parathyroid hormone (PTH) and magnesium (Mg) levels. Identifying these factors is a crucial step to minimize the occurrence of such complications.

Parathyroid Allotransplantation: Report of Outcomes in 3 Patients

BACKGROUND

Hypoparathyroidism is a relatively rare endocrine disorder defined as inadequate parathyroid hormone (PTH) secretion leading to a clinical syndrome characterized by hyperphosphatemia and hypocalcemia. This condition has high morbidity; patients present with a heterogeneous range of emotional, mental, and physical symptoms. We present our experience with PTH transplantation, using parathyroid glands surgically removed in the setting of secondary hyperparathyroidism, with a description of the clinical course, immunosuppressive management, and surgical technique.

METHODS

Between 2017 and 2021, 3 patients underwent parathyroid allotransplantation at the University of Illinois at Chicago. The 2 outcomes of interest were (1) symptomatic relief and improvement in calcium levels and (2) time to graft failure, defined as the presence of undetectable PTH levels.

RESULTS

All 3 patients experienced dramatic improvement in their debilitating symptoms, even though 2 patients required repeated PTH transplantation procedures. One patient had a remarkable course with symptom resolution, normalization of PTH levels, and a great reduction in calcium supplementation.

CONCLUSION

The use of hyperplastic glands from patients with secondary hyperparathyroidism undergoing 4-gland parathyroidectomy with autotransplantation represents an important source. However, a uniform definition of graft viability and prospective studies with long follow-ups are needed to address how much parathyroid tissue is optimally transplanted and the need for immunosuppression. Most patients affected by hypoparathyroidism are successfully managed by medical treatment; however, some do not respond to therapy and present debilitating symptoms related to hypocalcemia. This subgroup may benefit from parathyroid allotransplantation. Our 3 patients had remarkable improvement in their symptoms with the adoption of hyperplastic glands. Two out of 3 patients required multiple procedures to sustain symptom control.

The Challenge of Preoperative Panel Reactive Antibody Positivity in Parathyroid Transplantation

OBJECTIVES

Identifying suitable recipient criteria and matching recipients with appropriate donors are required to increase survival for parathyroid transplant. This study was undertaken to evaluate transplant survival rates while comparing preoperative panel reactive antibody positivity.

MATERIALS AND METHODS

The study included 14 hypoparathyroidism patients who presented to our clinic for parathyroid transplant. Preoperative ABO compatibility and negative cross-match tests were prioritized for recipient-donor matching, and panel reactive antibody screening tests were performed. During the 24-month follow-up, we evaluated medication use and serum calcium, phosphorus, and parathormone levels of patients.

RESULTS

Preoperative panel reactive antibody positivity was assessed in 3 groups. The HLA class I-positive group (mean fluorescence intensity range, 179-1770) showed decreased medication use and stability in serum calcium levels. The HLA class IIpositive (mean fluorescence intensity range, 85-3959) showed decreased medication use by 25% to 50% and returned to their former prescription doses after 12 months. An opposite pattern was observed in 2 patients with panel reactive antibody positivity for both HLA classes (mean fluorescence intensity range, 462-2289), with 1 patient requiring medication for continuing symptoms and the other patient occasionally taking additional magnesium supplementation, despite decreased medication doses after 12 months. Serum calcium levels remained normal, and parathormone and phosphorus levels were elevated.

CONCLUSIONS

Improving patient symptoms and having no requirement for intravenous calcium replacement are priorities, and monitoring serum levels is the next important step. Varied panel reactive antibody positivities and survival rates indicate a requirement, and each HLA class could require a proper limitation for the mean fluorescence intensity. Preoperative mean fluorescence intensity cut-off value should be <900. Higher mean fluorescence intensity values in panel reactive antibody screenings could increase risk of short-term graft survival after parathyroid transplant. Further studies should include immunological risk assessments by individualizing the outcome with donor-specific antibodies.

Parathyroid preservation in total endoscopic thyroid surgeries via the mammary areolas approach: Real-world data from a single center

BACKGROUND

Preserving parathyroid glands in situ is crucial to avoid surgical hypoparathyroidism, but it is also one of the greatest challenges during thyroid surgery. Magnified endoscopic imaging has been proposed as a way to improve parathyroid preservation.

METHODS

2,603 consecutive patients who underwent thyroid surgery at the First People's Hospital of Zunyi from January 2018 to July 2022 were screened. 1,355 patients were eligible, including 965 endoscopic and 390 open cases. Parathyroid hormone (PTH) loss levels and severe parathyroid injury rates were compared between endoscopic and open cases. Meanwhile, factors that contribute to parathyroid injuries were assessed, including surgical extent, tumor size, carbon nanoparticle guidance, and surgical proficiency.

RESULTS

PTH loss levels were similar between endoscopic and open cases (P = 0.440). The incidence of severe parathyroid injuries was also comparable (7.8% for endoscopic vs. 6.9% for open, P = 0.592). The endoscopic group had higher rates of autologous parathyroid transplantation (39.5% vs. 24.4%, P = 0.000), while accidental parathyroidectomy rates were similar (11.4% vs. 10.8%, P = 0.739). Among patients who received the same extent of thyroid surgeries, no significant difference was found in PTH loss levels and severe parathyroid injury rates, except for a higher risk of severe parathyroid injuries in endoscopic bilateral thyroidectomy (18.52% vs. 11.52%, P = 0.033).

CONCLUSIONS

Despite the magnified endoscopic imaging facilitating the identification of parathyroid tissues, endoscopic approaches are not superior to open ones for the in-situ preservation of parathyroid glands. For a bilateral thyroidectomy, open approaches are safer for parathyroid preservation.

Is parathyroid allotransplantation a viable option in the treatment of permanent hypoparathyroidism? A review of the literature

BACKGROUND

The standard clinical treatment for hypoparathyroidism, replacement of calcium and vitamin metabolites (calcitriol), has been used for decades; however, evidence points to its inefficiency in acting on the pathophysiology of the disease, which may precipitate or aggravate conditions already related to hypoparathyroidism. Therapies based on recombinant human parathyroid hormone have emerged in recent years but still have low availability due to their high cost. Parathyroid allotransplantation (Pt-a) has been reported as a strategy for treating more severe cases.

METHODS

This narrative review highlights relevant aspects of conventional permanent hypoparathyroidism treatment and provides a comprehensive and critical review of the reports of applications of Pt-a, especially those carried out in recent years. Particular focus is placed on the following key points: parathyroid immunogenicity, immunosuppression regimens (short-term or chronic), techniques to reduce the expression of immunogenic molecules, follow-up time, and reductions in calcium and vitamin D supplementation.

CONCLUSION

Pt-a has been considered a safe and relatively low-cost therapy and is believed to have the potential to cure the disease, in addition to treating symptoms. However, there is considerable heterogeneity in treatment protocols; therefore, more studies are required to improve the standardization of the procedure and thus improve the consistency of outcomes.

Diabetes mellitus postoperatif hipoparatiroidizm için bir risk faktörü olabilir mi?

Aim: Postoperative hypoparathyroidism (postop hypoPT) is usually seen after aggressive neck surgery, and can be fatal if left untreated. To the best our knowledge there is no study in literature that directly investigates the association between diabetes mellitus (DM) and postop hypoPT. In this study, we aimed to determine whether DM increases the risk of permanent postop hypoPT. Materials and Methods: Patients presenting to endocrinology outpatient clinic with a diagnosis of permanent postoperative hypoparathyroidism, were studied retrospectively. Patients older than 18 years of age were included in the study if one year had passed after the neck operation. Results: The average age of 131 patients who met the inclusion criteria was 49 ± 12. 93.9% of the patients were women and the patients were generally obese or overweight (mean body mass index= 30±5.29 kg/m2). While 14.5% of the patients were diabetic and 32.8% prediabetic (47.3% had impaired carbohydrate tolerance), 52.7% had normal glucose metabolism. Conclusion: The rate of DM / prediabetes (preDM) in patients diagnosed with postop hypoPT and the prevalence of DM / preDM in Turkish population were similar. Even though DM is associated with endothelial dysfunction, our findings suggest that DM is not a risk factor for postop hypoPT.

Simultaneous Kidney and Parathyroid Transplantation in the Management of Genetic Hypoparathyroidism in a Child

Background.

Genetically determined hypoparathyroidism can lead to life-threatening episodes of hypocalcemia and, more rarely, to end-stage kidney disease at a young age. Parathyroid allotransplantation is the only curative treatment, and in patients already receiving immunosuppression for kidney transplantation, there may be little additional risk involved. We report the first such case in a child.

Methods.

An 11-y-old girl, known to have hypoparathyroidism secondary to an activating pathogenic variant in the calcium-sensing receptor, developed end-stage kidney disease and was started on intermittent hemodialysis. Since the age of 2.5 y, she had been receiving treatment with exogenous synthetic parathyroid hormone (PTH). In June 2019, at the age of 11.8 y, she received a living-donor kidney and simultaneous parathyroid gland transplant from her father. The kidney was implanted into the right iliac fossa, followed by implantation of the parathyroid gland into the exposed rectus muscle.

Results.

The kidney graft showed immediate function while the intrinsic serum PTH level remained low at 3 ng/L. Exogenous PTH infusion was reduced on day 6 posttransplantation to stimulate PTH production by the new gland, which resulted in improving intrinsic PTH concentrations of 28 ng/L by day 9. Twelve months after transplantation, PTH levels remain in normal range and the kidney graft function is stable with a serum creatinine of 110 μmol/L.

Conclusions.

Simultaneous living donation and transplantation of a kidney and a parathyroid gland into a child is safe and feasible and has the potential to cure primary hypoparathyroidism as well as kidney failure.

Parathyroid Allotransplantation: A Systematic Review

Background: To date, there is no satisfactory treatment for patients with calcium and vitamin D supplementation refractive hypoparathyroidism. Parathyroid allotransplantation by design is a one-time cure through its restoration of the parathyroid function and, therefore, could be the solution. A systematic literature review is conducted in the present paper, with the aim of outlining the possibilities of parathyroid allotransplantation and to calculate its efficacy. Additionally, various transplantation characteristics are linked to success. Methods: This review is carried out according to the PRISMA statement and checklist. Relevant articles were searched for in medical databases with the most recent literature search performed on 9 December 2021. Results: In total, 24 articles involving 22 unique patient cohorts were identified with 203 transplantations performed on 148 patients. Numerous types of (exploratory) interventions were carried out with virtually no protocols that were alike: there was the use of (non-) cryopreserved parathyroid tissue combined with direct transplantation or pretreatment using in vitro techniques, such as culturing cells and macro-/microencapsulation. The variability increased further when considering immunosuppression, graft histology, and donor–recipient compatibility, but this was found to be reported in its entirety by exception. As a result of the large heterogeneity among studies, we constructed our own criterium for transplantation success. With only the studies eligible for our assessment, the pooled success rate for parathyroid allotransplantation emerged to be 46% (13/28 transplantations) with a median follow-up duration of 12 months (Q1–Q3: 8–24 months). Conclusions: Manifold possibilities have been explored around parathyroid allotransplantation but are presented as a double-edged sword due to high clinical diverseness, low expertise in carrying out the procedure, and unsatisfactory study quality. Transplantations carried out with permanent immunosuppression seem to be the most promising, but, in its current state, little could be said about the treatment efficacy with a high quality of evidence. Of foremost importance in pursuing the answer whether parathyroid allotransplantation is a suitable treatment for hypoparathyroidism, a standardized definition of transplantation success must be established with a high-quality trial.

HLA-DR, -DP, -DQ expression status of parathyroid tissue as a potential parathyroid donor selection criteria and review of literature

BACKGROUND

Basic and clinical studies about parathyroid allotransplantation have to be utilized with more definitive criteria for longer graft survival. Several reports demonstrated different isolation and cultivation methods for parathyroid cells to minimize their immunogenicity. In this study, we aim to compare and evaluate the clinical characteristics and the status of HLA class II expression changes in parathyroid tissue.

METHODS

A total of 22 parathyroid hyperplasia tissue donors was included in this study. Clinical characteristics were evaluated and compared with the HLA-DR, -DP, -DQ mRNA, and protein expression levels which were determined by qRT-PCR and Western blot.

RESULTS

We have compared the clinical characteristics (age, dialysis duration, frequency, recurrency of hyperparathyroidism and, calcimimetic usage) and HLA class II expression. HLA class II mRNA and protein levels showed varied expression patterns between tissues. Only, the HLA-DP has high mRNA expression levels without affecting the protein level when compared with the ages of the tissue donors. In addition, the HLA-DR, HLA-DP, and HLA-DQα1 protein expression levels showed a permanent and varied expression rate between tissues.

CONCLUSION

Expression of HLA class II molecules in parathyroid cells appears to constitute a decisive factor. Despite the lack of clinical outcomes, present data proposes new insight with a detailed understanding of parathyroid immunogenicity. In the future, randomized controlled clinical trials are needed for the accurate assessment of the effect of the varied HLA class II expression profiles in parathyroid tissue.

Number of cells in parathyroid tissue in primary hyperparathyroidism cases and its relationship with serum calcium value

BACKGROUND

The relationship between serum calcium (Ca) level to serum parathyroid hormone (PTH), phosphorus (P) levels and tissue properties of the parathyroid gland is unknown in primary hyperparathyroidism cases. Revealing this relationship may be useful for understanding the etiopathogenesis of primary hyperparathyroidism and determining the time of treatment.

METHODS

Ninety patients (71 females, 19 males, age range; 27-73 years, average age; 46) who underwent single gland excision with the diagnosis of primary hyperparathyroidism were studied. The patients were divided into 2 groups as serum Ca level <12 and serum Ca level ≥12. Age and sex of the patients, mean cell number of the gland, mean volume of the gland, serum levels of PTH, P, and histopathologic type of hyperplasia were evaluated.

RESULTS

The mean cell number per cubic centimeter is 22.9 (10-220 range) million in all glands. Serum Ca level was <12 in 82 (91.1%) of the patients, and ≥12 in 8 (8.9%) cases. Mean cell number of the gland, mean volume of the gland, existence of cystic hyperplasia of the gland, serum levels of PTH and P were statistically significant between the 2 groups (P < .001, P < .001, P < .05, P < .001, P < .05 respectively).

CONCLUSION

In primary hyperparathyroidism cases serum Ca level is not related to age and sex but directly related to proportionals to the cell number and volume of the gland and serum levels of PTH, inversely related to cystic hyperplasia and serum levels of P. Early surgical intervention should be planned since the serum Ca level will be high in large adenomas with a noncystic radiological appearance.

Hypoparathyroidism: State of the Art on Cell and Tissue Therapies

Hypoparathyroidism is an endocrine disorder characterized by low serum calcium levels, high serum phosphorus levels, and by inappropriate or absent secretion of the parathyroid hormone (PTH). The most common therapeutic strategy to treat this condition is hormone replacement therapy with calcium and vitamin D but, unfortunately, in the long term this treatment may not be sufficient to compensate for the loss of endocrine function. Glandular autotransplantation is considered the most effective technique in place of replacement therapy. Although it leads to excellent results in most cases, autotransplantation is not always possible. Allograft is a good way to treat patients who have not been able to undergo autograft, but this technique has limited success due to side effects related to tissue rejection. This therapy is supported by systemic immunosuppression, which leads to the onset of serious side effects in patients, with a risk of endocrine toxicity. Today, research on endocrine disorders is focused on discovering alternative graft therapies that can allow optimal results with the fewest possible side effects. In this review, we will make an update on the current state of the art about the cell and tissue therapy as treatment for hypoparathyroidism, to identify which type of therapeutic strategy could be valid for a future clinical use.

Parathyroid allotransplantation for the treatment of permanent hypoparathyroidism: A systematic review

BACKGROUND

Hypoparathyroidism is the most common complication of bilateral operations in the central neck. No formal guidelines exist for the management of permanent hypoparathyroidism. Current treatment involving medical supplementation increases resource utilization and patient morbidity while decreasing quality of life. Parathyroid allotransplant (PA) offers a promising therapy; however, the optimal technique and role of immunosuppression (IS) in PA remain unclear.

METHODS

We performed a systematic search of the Embase, MEDLINE, and Cochrane Library databases to identify studies investigating PA for treatment of hypoparathyroidism.

RESULTS

A total of 24 studies including 186 individual allograft transplants in 146 patients were identified. Pooled graft survival for allotransplants in transplant-naïve vs prior transplant recipients was 29.9% and 80%, respectively.

CONCLUSIONS

PA using normocellular, fresh parathyroid donor tissue that is ABO-compatible, with induction and, at minimum, short-term maintenance IS presents a potentially safe and effective therapeutic option for permanent hypoparathyroidism in patients tolerating IS.

MANAGEMENT OF ENDOCRINE DISEASE: Postsurgical hypoparathyroidism: current treatments and future prospects for parathyroid allotransplantation

BACKGROUND

Permanent postsurgical hypoparathyroidism (POSH) is a major complication of anterior neck surgery in general and of thyroid surgery in particular. Depending on diagnostic criteria, up to 10% of patients undergoing bilateral thyroid surgery develop POSH. This leads to a multitude of symptoms that decrease the quality of life and burden the healthcare provision through complex needs for medication and treatment of specific complications, such as seizures and laryngospasm.

METHODS

Narrative review of current medical treatments for POSH and of the experience accumulated with parathyroid allotransplantation.

RESULTS

In most patients, POSH is controlled with regular use of calcium supplements and active vitamin D analogues but a significant proportion of patients continue to experience severe symptoms requiring repeated emergency admissions. Replacement therapy with synthetic PTH compounds (PTH1-34, Natpara® and PTH1-84, teriparatide, Forsteo®) has been assessed in multicentre trials, but the use of this medication is restricted by costs and concerns related to the risk of development of osteosarcoma. Based on recent case reports of successful allotransplantation of parathyroid tissue between siblings, there is renewed interest in this technique. Data on selection of donors, parathyroid cell preparation before allotransplantation, site and timing of transplantation, need for immunosuppression and long-term outcomes are reviewed.

CONCLUSION

A prospective trial to assess the efficacy of parathyroid allotransplantation in patients with severely symptomatic protracted post-surgical hypoparathyroidism is warranted.

Discharging a Patient Treated With Parathyroid Allotransplantation After Having Been Hospitalized for 3.5 Years With Permanent Hypoparathyroidism: A Case Report

INTRODUCTION

Parathyroid allotransplantation is one of the methods used in the treatment of permanent hypoparathyroidism. We present a patient who underwent continuous intravenous (IV) calcium replacement therapy because of permanent hypoparathyroidism after total thyroidectomy.

CASE PRESENTATION

A 47-year-old woman who underwent a total thyroidectomy with a multinodular goiter developed hypoparathyroidism and hypocalcemia 1 week after discharge. The patient was started on daily oral calcitriol, magnesium effervescent, vitamin D, and IV calcium gluconate and was unable to be discharged because the IV calcium could not be stopped. After 3.5 years, 50×10⁶ parathyroid cells were transplanted by injecting the cells into the left deltoid muscle of the patient. The immunosuppression of the patient, who used 20-mg methylprednisolone for the first month, was completely discontinued.

RESULTS

No complications were observed in the patient after transplantation. The parenteral calcium replacement of the patient was progressively interrupted after transplantation. The patient's serum calcium level was 7.8 mg/dL and the PTH level was 6.9 pg/mL without IV calcium replacement at 12 weeks after transplantation, and the patient was discharged using oral ionized calcium. In the 10-week follow-up after discharge, the need for IV calcium was not observed in the patient.

CONCLUSION

Parathyroid allotransplantation is a simple, fast, and cost-effective method that should be tried in patients with persistent hypoparathyroidism, especially those who have to take IV calcium replacement, because its cost is much cheaper than standard medical care, its morbidity is much more limited, and it increases the patient's quality of life.

Importance of HLA typing, PRA and DSA tests for successful parathyroid allotransplantation

Parathyroid allotransplantation is increasingly practiced for patients who have permanent hypoparathyroidsm. Parathyroid allotransplantation success is varied, and no defined criteria about immunologic monitoring for pre-/post-transplantation follow-up. This study sought to evaluate the possible role of immunological tests. Four unrelated recipients and one living donor who have chronic kidney disease were evaluated for HLA-typing, PRA, CXM tests to conduct parathyroid allotransplantation. Parathyroid glands were obtained and resected from the donor, then cells were isolated and cryopreserved. Upon histologic examination, cells were cultivated and injected into muscle of four recipients. Recipient's were followed for parathormone and calcium levels for four years. PRA screening were monitored and de novo DSA was evaluated as well. In two of the recipients, allografts continued to be functional more than four years. In one recipient, allograft remained functional for two years and another recipient lost function after one year. Two out four were negative for de novo DSA and three out of four of the recipients remained negative for PRA. Neither HLA-matching nor de novo DSA positivity and PRA screenings seems significant for successfull parathyroid allotransplantation. This study has considerable potential for immunological monitoring of parathyroid allotransplantation.

Patients' views about parathyroid transplantation for post-thyroidectomy hypoparathyroidism

BACKGROUND

Permanent hypoparathyroidism (hypoPT) represents the most common postoperative complication associated with total thyroidectomy. Current treatment relies on high-dose calcium and/or vitamin D supplementation, but often this is insufficient and some patients remain symptomatic. Parathyroid allotransplantation is a new therapeutic option described recently in the literature. This study aims to investigate the patients' acceptability of parathyroid transplantation as a potential new treatment for hypoPT.

METHOD

Online survey of members of HypoParaUK, a support group for individuals affected by hypoPT.

RESULTS

Responses were received from 252 hypoPT patients. Majority declared to experience severe symptoms despite regular medical treatment. On a severity scale of 0-5, symptoms that were most troublesome were fatigue (3.8), low sense of well-being (3.5), and numbness/tingling (2.9). On a scale of 0-10, on average, their current quality of life (QoL) was 5 ± 3 and they expected this would improve to 7 ± 2 with correction of their hypoPT. Forty-four percent of patients were extremely interested in a potential technique involving intramuscular injection of parathyroid cell suspension compared to just 14% who were interested in the more invasive procedure of implantation of a parathyroid allograft into the forearm. The main concerns expressed were related to the possible need for immunosuppressive therapy.

CONCLUSION

Patients with severe symptomatic hypoPT seem interested to consider participation in a clinical trial exploring the feasibility and success rate of parathyroid transplantation.

A New Transport Solution for Parathyroid Allotransplantation: Effects on Cell Viability and Calcium-Sensing Receptors

BACKGROUND

Cold ischemia protects organs and tissues by slowing their metabolism, but it also causes ischemic injury. Minimizing cold ischemia has been an important goal in parathyroid auto- and allotransplantation, as well as the transplantation of other major organs. Parathyroid glands are responsible for calcium homeostasis by releasing parathormone (PTH) into the blood circulation. Functionality of a new parathyroid transport solution (NPTS) and effects on cell viability, PTH secretion, and calcium-sensing receptor (CaSR) levels during cold ischemia were evaluated.

MATERIALS AND METHODS

A NPTS was prepared, and the pH was adjusted to a range of 7.2-7.4 and kept at +4°C until use. Seven patients with parathyroid hyperplasia secondary to chronic renal failure who were scheduled to undergo subtotal parathyroidectomy were enrolled in the study. Glands were cold-preserved in NPTS with different time intervals (0, 6, 12, 18, and 24 hours), and then parathyroid cell viability before and after cryopreservation, PTH secretion, and CaSR levels were determined.

RESULTS

The mean cell viability before cryopreservation was 92.7% (range 89.2%-97.2%). There were no significant differences in cell viability rates before and after cryopreservation (p = 0.1168 and p = 0.4085, respectively), and CaSR levels (p = 0.5446) were not significant.

CONCLUSIONS

NPTS is a solution designed specifically for parathyroid tissue transplantation. This patent pending product can support cellular viability and PTH release, as well as protect CaSR functionality for up to 24 hours of cold ischemia.

American Thyroid Association Statement on Postoperative Hypoparathyroidism: Diagnosis, Prevention, and Management in Adults

BACKGROUND

Hypoparathyroidism (hypoPT) is the most common complication following bilateral thyroid operations. Thyroid surgeons must employ strategies for minimizing and preventing post-thyroidectomy hypoPT. The objective of this American Thyroid Association Surgical Affairs Committee Statement is to provide an overview of its diagnosis, prevention, and treatment.

SUMMARY

HypoPT occurs when a low intact parathyroid hormone (PTH) level is accompanied by hypocalcemia. Risk factors for post-thyroidectomy hypoPT include bilateral thyroid operations, autoimmune thyroid disease, central neck dissection, substernal goiter, surgeon inexperience, and malabsorptive conditions. Medical and surgical strategies to minimize perioperative hypoPT include optimizing vitamin D levels, preserving parathyroid blood supply, and autotransplanting ischemic parathyroid glands. Measurement of intraoperative or early postoperative intact PTH levels following thyroidectomy can help guide patient management. In general, a postoperative PTH level <15 pg/mL indicates increased risk for acute hypoPT. Effective management of mild to moderate potential or actual postoperative hypoPT can be achieved by administering either empiric/prophylactic oral calcium and vitamin D, selective oral calcium, and vitamin D based on rapid postoperative PTH level(s), or serial serum calcium levels as a guide. Monitoring for rebound hypercalcemia is necessary to avoid metabolic and renal complications. For more severe hypocalcemia, inpatient management may be necessary. Permanent hypoPT has long-term consequences for both objective and subjective well-being, and should be prevented whenever possible.

Short and long-term impact of parathyroid autotransplantation on parathyroid function after total thyroidectomy

The most common complication of total thyroidectomy is parathyroid insufficiency. Acute, transient, post-operative hypoparathyroidism increases length of hospitalization, morbidity and cost associated with total thyroidectomy. While permanent hypoparathyroidism poses a significant medical burden with lifetime medication, regular follow up and considerable disease burden related to chronic renal failure and other sequelae. Parathyroid autotransplantation has been demonstrated to result in biochemically functional grafts, leading to the procedures' common use during total thyroidectomy. The clearest indications for parathyroid auto transplantation are inadvertently removed or devascularized parathyroid glands. Some centers utilize routine autotransplantation to reduce the risk of permanent hypoparathyroidism. Novel fluorescence techniques to aid in parathyroid detection during thyroid surgery are under evaluation. This review aims to define the role and impact of parathyroid autotransplantation undertaken during total thyroidectomy.

Fresh tissue parathyroid allotransplantation with short-term immunosuppression: 1-year follow-up

BACKGROUND

Permanent hypoparathyroidism is a serious problem and requires medications indefinitely. Parathyroid allotransplantation (PA) with short-term immunosuppression is definitive choice but long-term results are not clear.

METHOD

We performed PA from two donors to two recipients. Both recipients were 39-year-old females. Donors were a 32-year-old female and a 36-year-old male, who both have chronic kidney disease. Routine tests, viral markers, and cross-matches were analyzed individually. The parathyroid glands were resected from the living donors, fragmented quickly in the operation room and injected into the left deltoid muscles of the two recipients.

RESULTS

Methylprednisolone was administered on post-PA day one and two. Recipients were discharged from the hospital without complications. Calcium and PTH levels were observed throughout 1 year. We did not observe any complications during the follow-up period. Medications ceased in post-transplantation week 1 for Case 1 and after 1 month for Case 2.

CONCLUSION

Fresh tissue PA with short-term immunosuppression appears to be a promising technique that is easy to perform, is cost-effective, has low risk of side effects and minimal complications with compatibility for HLA conditions. A longer follow-up period and more case studies are needed to determine the risks and benefits of this procedure for future cases.

Parathyroid transplantation in thyroid surgery

Permanent hypoparathyroidism following thyroid surgery is rare. Its prevalence is reported to be below 1-2% if surgery is performed by experienced thyroid surgeons. Parathyroid identification and preservation in situ with good vascular supply is the mainstay of safe thyroid surgery. However, if the parathyroid glands are damaged, autotransplantation should be undertaken to preserve their function. Parathyroid transplantation can be considered in three distinct modes of application: (I) fresh parathyroid tissue autotransplantation during thyroidectomy in order to reduce the risk of permanent hypoparathyroidism; (II) cryopreserved parathyroid tissue autotransplantation in patients with permanent hypoparathyroidism; (III) parathyroid allotransplantation in patients with permanent hypoparathyroidism when cryopreserved parathyroid tissue is not available for grafting. Nowadays, allotransplantation of cultured parathyroid cells without immunosuppression should be taken into consideration in selected patients as an alternative to calcium and vitamin D3 supplementation in management of permanent hypoparathyroidism. This paper is aimed to provide a review of current status of various parathyroid transplantation techniques in thyroid surgery.

Xenotransplantation of human cryopreserved parathyroid tissue isolated from parathyroid adenomas to normocalcemic rabbits

OBJECTIVE

Parathyroid allotransplantation is a new method for the treatment of permanent hypoparathyrodism. Adenoma cells are not used for transplantation because of the potential for functional or histopathologic transformation. In this study, we transplanted human adenomatous parathyroid cells to rabbits.

MATERIAL AND METHODS

Parathyroid adenoma tissue taken from a male patient was cryopreserved and transplanted into seven New Zealand white rabbits (mean weight, 3700±220 g; mean age, 4.5 months) under immunosuppression. The levels of parathormone, calcium and phosphorus were measured before and after transplantation, and the parathyroid cells were observed histopathologically.

RESULTS

Mean parathyroid hormone level was 0.5 pg/dL before transplantation and 6.6 pg/dL after transplantation (p<0.05). Preoperative mean calciumlevel was 14.1 mg/dL, and mean phosporus level was 3.5 mg/dL before transplantation while these values were 14.4 mg/dL and 3.3 mg/dL, respectively, after transplantation (p>0.05). Morphologic transformation was not observed in parathyroid cells after transplantation.

CONCLUSION

In short-term observation, adenomatous parathyroid cells can function without malignant transformation. In the future, the preliminary methodology in this study may serve as a safe alternative for allotransplantation into patients with permanent hypoparathyroidism.

Microencapsulation of Parathyroid Cells for the Treatment of Hypoparathyroidism

Cell encapsulation is an alternative to avoid rejection of grafted tissue, thus bringing an interesting alternative in cell therapy. It is particularly relevant in ailments where only the implant of small quantities of tissues is warranted. In such circumstances, the use of immunosuppressive therapy in patients implanted with tissues from donors is debatable, yet unavoidable at present in order to prevent rejection and/or sensitization of the host to the tissue, in turn jeopardizing the success of successive implants. Hence, a new line of thought, which aims to provide an immunoprivileged site for the grafted tissue, while at the same time insure its nutrition, as well as its survival and continued function, appears as a most attractive possibility. To achieve these goals, cells or tissues harvested for transplant could be encapsulated in biologically compatible matrices. Among the matrices currently in existence, sodium alginate is the most widely used polymer for tissue encapsulation.In the present chapter, we present a technique used to encapsulate parathyroid tissue, for use as cell transplant therapy in patients with secondary hypoparathyroidism. With this procedure, implanted tissue survives and remains functional for up to 18 months.

Adipose-derived stem cells: A novel source of parathyroid cells for treatment of hypoparathyroidism

Hypoparathyroidism is characterized by decreased function of the parathyroid glands with underproduction of parathyroid hormone (PTH), which can lead to low levels of calcium in the blood, often causing cramping and twitching of muscles or tetany, and several other symptoms. Severe hypocalcemia is a life-threatening condition. At present, both medical and surgical treatments are offered to improve the blood calcium, but they are not a cure. Adipose-derived stem cells (ADSCs), derived from the adipose tissue, are confirmed to be multipotent with adipogenic, chondrogenic, neurogenic, myogenic and osteogenic capabilities. Our hypothesis is that human ADSCs in culture can be differentiated into parathyroid cells, and used to reconstitute function.

Parathyroid Allotransplant With a New Technique: A Prospective Clinical Trial

OBJECTIVES

Parathyroid allotransplant is a valuable alternative in treating permanent hypoparathyroidism. However, it is a difficult process that requires several trained staff and advanced laboratory equipment, which makes the costs high. Here, we identify a new parathyroid allotransplant technique.

MATERIALS AND METHODS

After obtaining informed consent from patients, parathyroid cell suspensions obtained from 4 donors who had undergone a subtotal parathyroidectomy owing to chronic renal failure were transplanted in 10 patients with permanent hypoparathyroidism after short-term cell cultivation. Prednisolone were used as immunosuppressant for the first 10 days and discontinued thereafter.

RESULTS

Allograft function was observed in 7 patients (70%) at a mean follow-up of 12 months. Daily oral calcium and vitamin D supplementations discontinued totally in 7 patients. No major or minor complication was observed.

CONCLUSIONS

Our technique is simple, fast, and has a low cost, with a 70% success rate at a mean follow-up of 12 months. It requires few staff, minimal equipment, and short-term immunosuppressant use for maintenance. The technical developments of parathyroid allotransplant, as mentioned in this study, may be important in treating permanent hypoparathyroidism.

Parathyroid Allotransplant for Persistent Hypocalcaemia: A New Technique Involving Short-Term Culture

OBJECTIVES

To develop a new parathyroid allotransplant method for the treatment of permanent hypoparathyroidism.

MATERIALS AND METHODS

Parathyroid cells 50 × 10(6) derived from a parathyroid hyperplasia patient were transferred to a 61-year-old patient who had thyroidectomy 17 years earlier, allowing to papillary thyroid cancer; he was admitted to our outpatient clinic with symptomatic chronic hypocalcemia. Cell isolation, cryopreservation, and culturing were conducted according to a new protocol.

RESULTS

During a follow-up of 5 months, the patient had no complications that could indicate rejection, and clinical symptoms completely resolved without requiring any drug supplementation.

CONCLUSIONS

Here, we report a new method, enabling fast and cost-effective parathyroid allotransplant with maintained tissue viability sufficient to treat persistent hypocalcemia.

Xenotransplantation of human cultured parathyroid progenitor cells into mouse peritoneum does not induce rejection reaction

INTRODUCTION

Parathyroid progenitor cells devoid of immunogenic antigens were used for human allotransplantation. Although there were many potential reasons for the expiry of transplant activity in humans, we decided to exclude a subclinical form of rejection reaction, and test the rejection reaction in an animal model.

MATERIAL AND METHODS

Experiments were carried out on 40 conventional male mice in their third month of life. The animals were housed in groups of 10 per cage in 4 cages with fitted water dispensers and fed a conventional diet based on standard pellet food. They were divided into four groups of 10 animals each, three experimental groups and one control group. Identified progenitor cells were stored in a cell bank. After testing the phenotype, viability, and absence of immunogenic properties, the cells were transplanted into mouse peritoneum cavity.

RESULTS

Animals were observed for 9 weeks. At 9 weeks of observation, the mean serum PTH concentration in the experimental groups was 2.0-2.5 pg/ml, while in the control group it did not exceed 1.5 pg/ml. The immunohistochemical assays demonstrated that millions of viable cells with a phenotype identical to the endocrine cells had survived in the peritoneum. Histologic specimens from different internal organs stained for PTH revealed positive cells labelled with anti-PTH Ab in the intestinal lamina, brain, liver, and spleen.

CONCLUSIONS

In the present paper we have demonstrated that xenotransplantation may be used as a model for an explanation of the immunogenic properties of cells generated from postnatal organs for regenerative therapy.

Potential treatment of hypoparathyroidism with recombinant plasmids encoding preproparathyroid hormone

Hypoparathyroidism cannot be cured by oral or intravenous calcium supplements. Using molecular biology techniques to induce the production of PTH is an ideal option to treat hypoparathyroidism. In this study, we established a recombinant plasmid encoding a mutant preproPTH with a skeletal muscle creatine kinase promoter (pCKM-mPTH). The sequence of the chimeric pCKM-mPTH gene was fully consistent with the DNA sequence reported previously and the site-directed mutagenesis was completed. Overlapping and nested PCR showed that PTH was highly expressed in and secreted from skeletal muscle cells transfected with the pCKM-mPTH plasmid: the PTH concentration in the culture medium 24 h after transfection was 26.37 pg/l. In the rat hypoparathyroidism model, serum PTH level significantly increased after injection with the pCKM-mPTH plasmid, compared with control groups (p<0.01). The effect lasted for about 30 days. Our results indicated that the recombinant mutant pCKM-mPTH plasmid was successfully constructed and was highly expressed in skeletal muscle cells. In vivo, the plasmid was introduced successfully into rat muscles and could express PTH for a decent period of time.

Induction of tolerance to parental parathyroid grafts using allogeneic thymus tissue in patients with DiGeorge anomaly

DiGeorge anomaly can affect both thymic and parathyroid function. Although athymia is corrected by allogeneic thymus transplantation, treatment options for hypoparathyroidism have been unsatisfactory. Parathyroid transplantation offers the potential for definitive cure but remains challenging because of graft rejection. Some allogeneic parathyroid grafts have functioned in adult recipients in the context of immunosuppression for renal transplantation. Other efforts have attempted to reduce the allogenicity of the parathyroid grafts through manipulation of the parathyroid tissues before transplantation (by using encapsulation or special culture techniques). Recently, we demonstrated the efficacy of parental parathyroid transplantation when combined with allogeneic thymus transplantation in an infant with complete DiGeorge anomaly. The recipient developed tolerance toward the parathyroid donor. The parathyroid graft has functioned for 5 years after transplantation without the need for continued immunosuppression or calcium supplementation. We observed that matching of the allogeneic thymus graft to the parathyroid donor HLA class II alleles that are unshared with the recipient appears to be associated with the induction of tolerance toward the parathyroid graft. Further work is needed to determine the optimal means for using combined allogeneic thymus and parental parathyroid transplantation to correct hypoparathyroidism in patients with both complete and partial DiGeorge anomaly.

Generation and identification of thymic epithelial progenitor cells pTEC by in-vitro processing of human thymic fragments for allotransplantation

The procedure of generation and identification of stromal progenitor cells derived from human thymic fragments (PL patent 378431) has been described in this article. Our aim was to prepare material for transplantation in elderly people. The method is based on in-vitro processing of thymic fragments to get rid of all immunogenic elements of lymphocytes, endothelial cells, macrophages, and fibroblasts. In the thymic culture process, this organ dies out in the incubation medium and epithelial cells emerge out of the organ. After about 4 weeks from the start of the culture, the population of various developmental forms of epithelial cells was generated, namely CK AE1/AE3+, SDF-1 alpha+ and a weak expression of FGF+ S-100+. Finally, we obtained approximately 3 million cells as a monolayer. The progenitor cells were experimentally transplanted into a 72-year-old volunteer in order to prove that they do not induce neither a local nor a systemic rejection response.

Mechanisms of tolerance to parental parathyroid tissue when combined with human allogeneic thymus transplantation

BACKGROUND

The induction of tolerance toward third-party solid organ grafts with allogeneic thymus tissue transplantation has not been previously demonstrated in human subjects.

OBJECTIVE

Infants with complete DiGeorge anomaly (having neither thymus nor parathyroid function) were studied for conditions and mechanisms required for the development of tolerance to third-party solid organ tissues.

METHODS

Four infants who met the criteria received parental parathyroid with allogeneic thymus transplantation and were studied.

RESULTS

Two of 3 survivors showed function of both grafts but subsequently lost parathyroid function. They demonstrated alloreactivity against the parathyroid donor in mixed lymphocyte cultures. For these 2 recipients, parathyroid donor HLA class II alleles were mismatched with the recipient and thymus. MHC class II tetramers confirmed the presence of recipient CD4(+) T cells with specificity toward a mismatched parathyroid donor class II allele. The third survivor has persistent graft function and lacks alloreactivity toward the parathyroid donor. All parathyroid donor class II alleles were shared with either the recipient or the thymus graft, with minor differences between the parathyroid (HLA-DRB1∗1104) and thymus (HLA-DRB1∗1101). Tetramer analyses detected recipient T cells specific for the parathyroid HLA-DRB1∗1104 allele. Alloreactivity toward the parathyroid donor was restored with low doses of IL-2.

CONCLUSION

Tolerance toward parathyroid grafts in combined parental parathyroid and allogeneic thymus transplantation requires matching of thymus tissue to parathyroid HLA class II alleles to promote negative selection and suppression of recipient T cells that have alloreactivity toward the parathyroid grafts. This matching strategy may be applied toward tolerance induction in future combined thymus and solid organ transplantation efforts.

Allotransplantation of cryopreserved parathyroid tissue for severe hypocalcemia in a renal transplant recipient

We report the successful allotransplantation of cryopreserved parathyroid tissue to reverse hypocalcemia in a kidney transplant recipient. A 36-year-old male received a second deceased donor kidney transplant, and 6 weeks later developed severe bilateral leg numbness and weakness, inability to walk, acute pain in the left knee and wrist tetany. His total calcium was 2.6 mg/dL and parathormone level 5 pg/mL (normal 10-60 pg/mL). He underwent allotransplantation of parathyroid tissue cryopreserved for 8 months into his left brachioradialis muscle. Immunosuppression included tacrolimus (target C(0) 10-12 ng/mL), mycophenolate mofetil and steroids. Within 2 weeks, the left knee pain, leg weakness and numbness resolved, and by 1 month he could walk normally. After a peak at month 2, his parathyroid hormone (PTH) level fell to <10 pg/mL; therefore at month 3 he received a second parathyroid transplant from the same donor. Eight months later (11 months after initial graft) he has a total calcium of 9.3 mg/dL, PTH level 15 pg/mL and is clinically asymptomatic. The amount of parathyroid tissue needed to render a patient normocalcemic is not known. In our case, the need for second transplant suggests that the amount of tissue transferred for an allograft may need to be substantially greater than for an autograft.

A case of human intramuscular adrenal gland transplantation as a cure for chronic adrenal insufficiency

Intramuscular endocrine gland transplantation has been well described as it pertains to parathyroid autotransplantation; however, transplantation of the adrenal gland is less well characterized. While adrenal autotransplantation in the setting of Cushing's disease has been described, intramuscular adrenal allotransplantation as a cure for adrenal insufficiency to our knowledge has not been previously carried out. Current treatment for adrenal insufficiency leaves patients without diurnal variation in cortisol release and susceptible to the detrimental effects of chronic hypercortisolism. We describe here the case of a 5-year-old girl with renal failure who had adrenal insufficiency following fulminant meningococcemia that led to requirements for both stress-dose steroid and mineralocorticoid replacement. Ten months after the onset of her disease, she received a simultaneous renal and adrenal gland transplant from her mother. The adrenal gland allograft was morselized into 1 mm(3) segments and implanted into three 2 cm pockets created in her rectus abdominis muscle. Three years after surgery, her allograft remains fully functional, responding well to adrenocorticotropin hormone stimulation and the patient does not require any steroid or mineral-corticoid supplementation. We believe this case represents the first description of successful functional intramuscular adrenal allograft transplantation with long-term follow up as a cure for adrenal insufficiency.