Stem cells have been used to grow a hormone producing thyroid. This is the first report of that gland being regenerated from stem cells. From Scientific American by way of Nature:

Costagliola and her colleagues first genetically engineered embryonic stem cells to express two proteins — NKX2-1 and PAX8 — that are expressed together only in the thyroid. When these cells were grown in Petri dishes in the presence of thyroid-stimulating hormone, they turned into thyroid cells.

Thyroid cells, however, have to be organized into a particular three-dimensional shape before they can work. They need to form small, spherical follicles containing a cavity in which iodide — a component of some hormones produced in the thyroid gland — can be concentrated before being absorbed and used for hormone synthesis.

Remarkably, the stem-cell-derived thyroid cells spontaneously grouped into follicles similar to those in an intact thyroid gland. And Costagliola and her colleagues found that the follicles were able to trap iodide and synthesize thyroid hormones. “When started the project, our hope was to get some cells that could be used to study thyroid physiology,” says Costagliola. “We never expected to get thyroid follicles.”