Scientists at Kyoto University have created a lab model that coaxes human induced pluripotent stem cells (iPSCs) into the full range of thymic epithelial cells that normally develop inside the thymus gland. The thymus is where immune T cells mature and learn to distinguish self from foreign — a process that declines with age. Using precise doses of retinoic acid followed by self-directed growth, the team generated immature thymic progenitors and multiple mature cell types resembling those found in the fetal thymus. When these lab-grown thymus cells were combined with developing immune cells, they successfully produced naïve T cells with diverse immune receptors — the hallmark of a healthy adaptive immune system. This platform opens doors to studying immune aging, thymic disorders, and potential cell therapies.
