ABSTRACT
BACKGROUND: Engineered cell sheet transplantation has been considered an alternative physiological therapy for endocrine disorders. In this study, we attempted to fabricate functional human thyroid cell sheets using the engineering technology by culturing primary thyrocytes in free-feeder monolayers and assessed their proliferation and function in two different media. METHODS: The non-tumorous tissues (approximately 2 g) were dissected during surgery. Primary human thyroid cells were isolated by mechanical dispersion and treatment with isolation solution. The cells were cultured on tissue culture dishes or temperature-responsive culture dishes to induce the formation of detached cell sheets. RESULTS: Primary thyroid cells isolated from nine patients were positive for thyroid transcription factor 1, thyroglobulin (TG) and cytokeratin 7. Cell sheets with follicles were fabricated by cells incubated in both Dulbecco's Modified Eagle Medium (DMEM) and hepatocyte-defined medium (HDM) culture medium. The diameter and thickness of sheets fabricated in HDM were larger and thicker than those fabricated from DMEM. Furthermore, the cells incubated in HDM secreted higher levels of fT3 and fT4 than those incubated in DMEM. The thyroid peroxidase and TG mRNA of cells maintained in HDM were higher than those in cells maintained in DMEM. CONCLUSION: HDM appears suitable as a culture medium for maintaining primary thyrocytes and fabricating functional cell sheets. These in vitro findings may contribute to the development of appropriate culture conditions for human thyrocytes as well as engineered functional cell sheets.