Generation and Functional Verification of Hypoxia-Sensitive Chimeric Antigen Receptor-T Cells

Extensive studies have proven the promise of chimeric antigen receptor T (CAR-T) cell therapy in treating hematological malignancies. However, treating solid tumors remains challenging, as exemplified by the safety concerns that arise when CAR-T cells attack normal cells expressing the target antigens. Researchers have explored various approaches to enhance the tumor selectivity of CAR-T cell therapy. One representative strategy along this line is the construction of hypoxia-sensitive CAR-T cells, which are designed by fusing an oxygen-dependent degradation domain to the CAR moiety and are strategized to attain high CAR expression only in a hypoxic environment-the tumor microenvironment (TME). This paper presents a protocol for the generation of such CAR-T cells and their functional characterization, including methods to analyze the changes in CAR expression and killing capacity in response to different oxygen levels established by a mobile incubator chamber. The constructed CAR-T cells are anticipated to demonstrate CAR expression and cytotoxicity in an oxygen-sensitive manner, thus supporting their capability to distinguish between hypoxic TME and normoxic normal tissues for selective activation.