Improved protocol for isolation and characterization of human thymic epithelial cells

Thymic epithelial cells (TECs) play a vital role in the generation of immunocompetent and immunotolerant T cells. The understanding of TEC biology in model animals such as mice has advanced thanks to the cellular and molecular analyses of purified TEC populations, including cortical TECs (cTECs) and medullary TECs (mTECs). On the other hand, studies of human TECs have fallen behind because of the lack of a well-established method for purifying TEC populations. Here, we show that using 0.5 U/ml liberase to digest thymus tissue into single cells is quicker than using collagenase D or 0.1 U/ml liberase. Thymus digestion with 0.5 U/ml liberase preserves CD205 expressed by cTECs. RNA sequencing analysis of TEC populations isolated from 0.5 U/ml liberase-digested human thymic tissue revealed the expression of molecules known as cTEC- and mTEC-specific genes in mouse thymus in each human TEC population. Our study is expected to fuel further cellular and molecular studies of human TECs, including those related to the collapse of immune tolerance in humans.