DNA-MEDIATED AND VIRAL-MEDIATED GENE-TRANSFER IN FOLLICULAR CELLS - PROGRESS TOWARD GENE-THERAPY OF THE THYROID

The authors investigate the in vitro component of an ex situ strategy for gene transfer into the thyroid gland using DNA complex and retrovi ral vectors. Canine follicular cells harvested by unilateral lobectomy and grown in low-serum media proliferated in culture and retained the ir differentiated state as evidenced by morphology and thyroglobulin e xpression. Transient and ''stable'' gene transfer in thyroid cells wer e evaluated by comparing DNA and retroviral transduction techniques. E ffective gene transfer and expression was demonstrated by histochemica l staining for the marker gene product beta-galactosidase. The efficie ncy of transduction was assessed using an amphotropic retroviral vecto r carrying the neomycin resistance gene and semiquantitative polymeras e chain reaction (PCR) identification of integrated proviral sequences . This analysis demonstrated a proviral frequency in transduced cultur es of 10% to 30%. Transduced cells showed no change in morphology or g rowth patterns and maintained differentiated function as assessed by a ntibody staining for thyroglobulin. The thyroid gland is an attractive target for somatic gene therapy because of its large protein-syntheti c capacity, sensitivity to hormonal regulation, and proportionately hi gh blood flow. Follicular cell gene therapy may be useful not only for treating congenital or acquired diseases of the thyroid, but also dis orders of circulating proteins such as hypopituitarism, hemophilia, an d diabetes.