Total Thyroidectomy in the Mouse: the Feasibility Study in the Non-thyroidal Tumor Model Expressing Human...

This study sought to probe the feasibility of performing total thyroidectomy in the mouse using a non-thyroidal hNIS expressing tumor model.

Our thyroidectomy protocol included thorough excision of both lobes and the isthmus. For evaluating the completeness of thyroidectomy, we compared the (99m)Tc-pertechnetate scans taken before and after thyroidectomy. The prostate cancer cell line was subcutaneously inoculated 2 weeks after the thyroidectomy. When the tumor reached 5-10 mm in diameter, Ad5/35-E4PSESE1a-hNIS was injected intratumorally, and (131)I scans were performed. The radioiodine uptakes of the neck and the tumor were compared with those of the other regions.

Total thyroidectomy was performed in 13 mice. Although 38.5% died during or just after thyroidectomy, the others survived in good health for 2 months. Thyroid tissue was completely eliminated using our protocol; the residual uptake of (99m)Tc-pertechnetate was minimal in the neck area. The neck/background uptake ratio after thyroidectomy was significantly lower than that before thyroidectomy (p < 0.05). Non-thyroidal tumor models were successfully established in all the surviving mice. Radioiodine accumulation in the tumors was visualized on (131)I scans, and the neck uptakes were minimal.

Using our total thyroidectomy protocol, we successfully established a hNIS-transfected prostate cancer model with a minimal accumulation of radioiodine in the neck. The relatively high mortality after surgery can be a problem, and this might be reduced by minimizing the surgical stress.