COVER Lipid nanoparticles (spheres) use antibodies against the CD5 protein (antibodies, blue; CD5, red) to specifically target T cells while inside the bloodstream and tissues. The nanoparticles deliver mRNA to T cells, reprogramming them in vivo to transiently express chimeric antigen receptors (gold) that target pathogenic cardiac fibroblasts. In vivo–engineered T cells mitigate cardiac fibrosis and improve heart function in a mouse model. See pages 23 and 91.
Illustration: C. Bickel/Science