Mount Sinai researchers demonstrated that in vivo generation of CAR‑T cells targeting fibroblast activation protein alpha (FAP) on hepatic stellate cells significantly reduced liver fibrosis and reversed organ damage in preclinical models of metabolic dysfunction‑associated steatohepatitis (MASH). The approach generates CAR‑T cells directly in the body, bypassing ex vivo manufacturing. By selectively eliminating FAP‑expressing stellate cells, the therapy produced durable antifibrotic effects without systemic toxicity in animal studies. If translated to humans, the in vivo CAR‑T strategy could offer a scalable, lower‑cost alternative for treating fibrotic liver disease, a leading cause of liver transplantation and an area with few effective pharmacologic options.