In the past decade, there have been many reports that provide evidence about the multi-lineage potential of stem cells, [1–3]. Adult stem cells have shown board plasticity that has allowed treatment of heart, liver and principally, blood related disorders, [1, 4]. This plasticity and the availability of adult bone marrow stem cells have made them a very promising source for research and clinical treatments.
The use of Iodine-131 (I131) to treat patients with hyperthyroidism, Grave's disease, has common side effects such as hypothyroidism that can be permanent [5–12]. In children and adolescent cases, hypothyroidism have been reported in 50 to 95% of patients at 1 year after treatment with Iodine-131 [13–15]. Most studies on the effects of Radioactive Iodine (RAI) on thyroid function conclude that this change is permanent, which is why many patients remain hypothyroid and have the physiological need to use supplemental thyroid hormones for the rest of their lives. Previous attempts to restore the thyroid function have been made by the removal and cryopreservation of thyroid tissue before treatment with I131, . Stem cells might offer a new therapeutic approach, instead of using cryopreserved thyroid tissue, but it has not been studied yet.
It is a well-known fact that bone marrow cells (BM) can give rise to hepatic oval cells, hepatocytes, cholangiocytes, skeletal-muscle cells, astrocytes, and neurons. Nonetheless, no studies report the use of BM cells in endocrine disorders like hypothyroidism [2, 3]. To investigate whether adult bone marrow cells are able to aid in the reconstitution of thyroid parenchyma, we conducted a study based on the implantation of male derived BM cells into thyroid gland of female rats previously treated with RAI to induce an iatrogenic state of low T4 and elevated TSH, [17–20]. It has been shown that the embryonic stem cells can differentiate in vitro like cells under the stimuli of TSH, . Our study, using low dose RAI, will create an animal model of transient elevation of TSH and with transplantation of male derived BM cells, it is possible to asses their effect on thyroid function, and if they are able, to participate in the repair of thyroid parenchyma.