Alteration in density, morphology and parathyroid hormone release of dispersed parathyroid cells from patients with hyperparathyroidism

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.

Total parathyroidectomy with autotransplantation in renal hyperparathyroidism: low recurrence after intra-operative tissue selection

BACKGROUND

Total parathyroidectomy with simultaneous autotransplantation (AT) is a well-established surgical modality in the treatment of severe drug-resistant renal hyperparathyroidism. In literature, the high rate of graft-dependent recurrence seems a serious disadvantage. This complication can possibly be avoided by parathyroid tissue selection prior to AT.

METHODS

Total parathyroidectomy with simultaneous AT was performed in 37 patients on intermittent haemodialysis treatment. Parathyroid tissue with a low proliferative potential ('A-regions') was selected for AT intra-operatively with a stereomagnifier. The mean post-operative follow-up was 37+/-24 months.

RESULTS

Plasma levels of intact parathyroid hormone decreased from 1211+/-541 to 69+/-32 pg/ml, calcium from 2.49+/-0.27 to 2.17+/-0.30 mmol/l, phosphorus from 2.28+/-0.63 to 2.11+/-0.69 mmol/l, and total alkaline phosphatases from 272+/-210 to 117+/-70 U/l. Graft-dependent recurrent hyperparathyroidism occurred in one patient after 32 months and was cured by the selective removal of five enlarged autografts.

CONCLUSIONS

Simply discriminating between diffuse and nodular hyperplastic parathyroid tissue appears to be inadequate. Intra-operative tissue selection with a stereomagnifier may facilitate the identification and AT of tissue with optimal functional characteristics and a low proliferative potential, thus minimizing the rate of recurrent hyperparathyroidism.

X-ray microanalysis of elemental changes in human parathyroid glands in primary and secondary hyperparathyroidism

The elemental composition of chief cells of parathyroid glands from patients with adenomatous primary hyperparathyroidism (HPT) and uremic secondary HPT was studied by X-ray microanalysis. Glands histologically deemed normal were used as controls. The analyses were also carried out on tissue specimens incubated in hypo-, normo- and hypercalcemic media (0.5, 1.25, and 3.0 mM calcium concentration). Analysis of chief cells from normal glands did not reveal any significant differences in ionic composition after exposure to the different calcium concentrations. In chief cells from adenomatous and uremic hyperplastic glands, elemental changes were noted. In comparison with specimens incubated in 1.25 mM calcium medium, cells in 0.5 mM calcium medium had a lower content of potassium and phosphorus. After stimulation with increasing extracellular concentration, an increase in the K/Na ratio was observed, due to a marked decrease of sodium and an increase of potassium; the calcium concentration was almost unchanged. Our findings indicate that in HPT an increase in serum calcium concentration might exert a stimulatory effect on the Na/K pump (sodium pump) and on the calcium-activated potassium channels. Either of these mechanisms might contribute to a lowering of cytoplasmic calcium. Our observations suggest that changes in ionic content of the parathyroid cells may be of importance for the stimulus secretion process in the cells.

1,25(OH)2D3 inhibits hormone secretion and proliferation but not functional dedifferentiation of cultured bovine parathyroid cells

Increasing the extracellular Ca2+ concentration from 0.5 to 3.0 mM induced marked increments in cytoplasmic Ca2+ concentration (Ca2+i) and inhibition of parathyroid hormone (PTH) release of freshly isolated bovine parathyroid cells. 1,25-dihydroxycholecalciferol (1,24(OH)2D3; 0.1-100 ng/ml) did not affect (Ca2+i) and was also without acute effect on the secretion. During 4 days of monolayer culture, the parathyroid cells underwent significant increases in both number and size, and presence of 10-100 ng/ml 1,25(OH)2D3 almost completely inhibited the cell proliferation, whereas the hypertrophy was unaffected. One day of culture with 0.1-100 ng/ml 1,25(OH)2D3 was without effect on PTH release but after 4 days there was a dose-related reduction of secretion. At this time point and irrespective of the culture condition, PTH release was no longer suppressed by high extracellular Ca2+. Furthermore, Ca2+i increased little upon increments in the extracellular Ca2+ concentration as compared with freshly isolated cells. It is concluded that after prolonged exposure to 1,25(OH)2D3, PTH release is inhibited and, at high concentrations, the parathyroid cells cease to proliferate. However, 1,25(OH)2D3 does not affect the development of functional dedifferentiation of parathyroid cells during monolayer culture.

Monoclonal antibodies with exclusive reactivity against parathyroid cells and tubule cells of the kidney

Four monoclonal anti-parathyroid antibodies were generated after immunization of mice with intact cells from human parathyroid tissue. All four monoclonal antibodies reacted in immunohistochemistry with structures present on parathyroid epithelial cells and proximal-tubule cells of the kidney but were unreactive with all other human tissues investigated. Immunofluorescence microscopy on suspended human parathyroid cells showed that the antibodies reacted with structures present on the cell surface. Two of these antibodies efficiently blocked the increase in cytoplasmic calcium concentration of parathyroid cells that is normally associated with increased concentrations of extracellular calcium. The results indicate that these two antibodies interfere with a calcium-sensing mechanism of parathyroid cells--i.e., a potential calcium receptor by which extracellular calcium regulates cytoplasmic calcium and hormone release in these cells.