The thyroid is a tiny organ, but it can cause some big problems if it malfunctions – and there are quite a few ways in which it can malfunction. It’s also especially problematic because while other organ problems can be corrected through transplantation, thyroid transplants aren’t done – the risks of rejection and problems caused by immunosuppression are considered to far outweigh the benefits compared to treatment with drugs. That may change soon, though. The reason scientists are so eager to use 3D bioprinting to create transplantable organs is not only because organs can be created on demand, rather than waiting for a donor – but also because organs created from a patient’s own stem cells carry much less risk of rejection.
In 2015, a group of scientists at Russian company 3D Bioprinting Solutions made history when they successfully 3D printed and transplanted a thyroid gland into a mouse. We’ve now received an update on the scientists’ research, which has been published in a paper entitled “Bioprinting of functional vascularized mouse thyroid gland construct,” available here.
Despite the complex problems it can cause, the thyroid gland is a fairly simple structure, making it an easy candidate for 3D printing.
The researchers utilized a scaffold-free 3D printing technique using tissue spheroids, which are capable of fusing on their own. Thyroid spheroids (TS) and allantoic spheroids (AS) were used as sources for thyrocytes and endothelial cells (EC), and a custom bioprinter was used to print the spheroids in tight formation within a collagen hydrogel. The endothelial cells, placed in close proximity to the thyroid spheroids, invaded and vascularized them, while the epithelial cells from the thyroid spheroids formed follicles.
The 3D printed thyroids were then transplanted into mice with hypothyroidism. After three and five weeks, the mice were tested and showed significant elevation of critical thyroid hormone levels, indicating that the bioprinted organ constructs were indeed doing the work they had been designed to do. Histological evaluation also showed that the bioprinted thyroids were able to successfully mature and integrate with the rest of the body.