Parathyroid allotransplantation without immunosuppression

The hypocalcaemia of permanent hypoparathyroidism is a severe and sometimes fatal complication after thyroid and parathyroid surgery. Due to the multiple metabolic functions of parathyroid hormone, the symptoms and associated diseases of hypoparathyroidism cannot always be controlled sufficiently with oral calcium and vitamin D supplements. We report the successful treatment of two patients with postoperative hypoparathyroidism by allotransplantation of cultivated parathyroid tissue particles that were encapsulated with a semipermeable membrane (microencapsulation). A 52-year-old woman and a 55-year-old woman had postoperative hypoparathyroidism after subtotal bilateral thyroid resection for multinodular goitre. To relieve symptoms the hypocalcaemia was treated with intravenous calcium (8 g and 4 g calcium per day, respectively) and high-dose oral vitamin D. Intact parathyroid hormone was not detectable in the serum of the two patients. Parathyroid allotransplantation was considered because both patients suffered from tetany, bone pain, depression, and impaired vision. Previous studies showed that MHC class I and II antigens are expressed on parathyroid tissue and their concentrations might determine graft outcome. Reduction of MHC expression can be achieved by depletion of immunogenic MHC-bearing cells with magnetic microspheres or tissueculture passages. The combination of microencapsulation and tissue-culture passage provides the key for successful isotransplantation, allotransplantation, and xenotransplantation of parathyroids as shown in long-term animal studies. The donor for both patients was an ABO compatible, HLA-mismatched patient with parathyroid hyperplasia due to secondary hyperparathyroidism. After parathyroidectomy, the tissue was cut into pieces of 1 mm. These particles were immersed in amitogenic degassed 2% sodium-alginate. The alginate was configured to allow nutritive substances as well as parathyroid hormone to pass through the membrane, while excluding immunogens and mediators of the cellular immune response. The suspension was passed through a spray nozzle (inner diameter 2 mm) for encapsulation with a constant flow of 6·5 L/min. The resulting spheres (microcapsules) were hardened by a 7-min incubation in 10 mmol/L barium chloride. Following multiple washes, microcapsules were cultured (RPMI 1640 with glutamine, 10 000 μg/mL streptomycin and penicillin, 10% fetal calf serum, and 2·4 mmol calcium chloride) for 2 days. 20 microcapsules were then transplanted into the brachioradial muscle of the non-dominant forearm. The study protocol was approved by the ethics committee of the Philipps-University of Marburg and written informed consent was given by both patients. The serum concentrations of total calcium and intact parathyroid hormone (iPTH) in one of the patients before and after allotransplantation are presented in the figure. The serum values of calcium and iPTH of the other case showed similar increases. For both patients calcium and vitamin D replacement therapy was reduced by half daily, beginning the first day after allotransplantation. They were discharged from the hospital without any hypocalcaemic symptoms and with no immunosuppressive therapy. The oral calcium and vitamin D replacement therapy was 0·6 g and 0·25 μg daily, in both patients, respectively. The combination of tissue-culture passage and microencapsulation could make parathyroid allotransplantation a practical option for successful treatment completely (table). No side effects were observed. Palpation showed softening of sclerotic lesions. Histopathological analysis of skin biopsy specimens taken 18 h after the last UVA-1 irradiation of this treatment course revealed dermal collagen with a thickness close to that of normal skin. ISH was done on formalin-fixed and paraffin-embedded tissue specimens with human interstitial collagenase-specific mRNA transcript. The probe sequence (5'dGGA AGC CAA AGG AGC TGT AGA TGT CCT-3') was unique when compared with all primate nucleic-acid sequences registered in the Entrez database. For IHC a monoclonal mouse serum (antibody 41-IE5, Oncogene Research Products, Cambridge, MA, USA) specific for human MMP-1 protein was used and immunohistochemically labelled. Both assays produced colorimetric reactions of variable intensity (table). In pretreatment specimens, a specific colorimetric signal was either absent (–) or weak (+) in fibroblastic cells. After UVA-1 treatment, an increase of interstitial collagenase m-RNA and protein expression was detected separately in most dermal fibroblastic cells. Here, a moderate (++) to strong (+++) signal was identified either by ISH, IHC, or both in all tissue specimens. In two of the lesions, signal intensity was greatest in fibroblasts of the upper papillary dermis. In both assays, UVA-1 phototherapy induced an increased signal for interstitial collagenase, weaker than that seen in fibroblasts, mainly in the upper layer of keratinocytes, melanocytes, and endothelial cells. Our results show that UVA-1 irradiation indeed induces expression of interstitial collagenase in fibroblasts of sclerotic morphea plaques. Together with the clinical and histological improvement of skin lesions, this is evidence that UVA-1 phototherapy acts by induction of interstitial collagenase in the clearance of morphea. In other studies, UVA-1 phototherapy has been shown to induce a variety of cytokines and soluble factors thereby causing profound immunomodulation. Our results also suggest that UVA-1 irradiation may also be of therapeutic benefit in other conditions characterised by excessive collagen production including keloid scars and a variety of rheumatological diseases.