388: Base by Base | Episode 388 — In situ CAR‑macrophage alleviates liver fibrosis

Huang X et al., Proceedings of the National Academy of Sciences (PNAS) - This episode summarizes a PNAS study reporting CD163‑targeted lipid nanoparticles that deliver FAP‑specific CAR mRNA to liver macrophages in situ, producing CAR‑macrophages that clear activated hepatic stellate cells and promote fibrosis resolution in mouse models. Key terms: FAP‑CAR, macrophage, lipid nanoparticles, liver fibrosis, MMP12. Study Highlights:The authors engineered CD163 antibody–conjugated LNPs (αCD163/LNP‑FAPCAR) to selectively transduce liver macrophages with FAP‑targeting CAR mRNA, yielding in situ CAR‑macrophages. CAR‑M showed enhanced phagocytosis and cytotoxicity toward FAP+ hepatic stellate cells and activated Syk/MyD88/NF‑κB signaling, with induction of MMP12. In multiple mouse fibrosis models (CCl4, BDL, MCD diet), treatment reduced ECM and fibrosis markers, improved histology and hepatocyte regeneration, and reshaped macrophage subsets toward MMP12+ scar‑resolving states. Safety profiling showed no major organ toxicity in treated mice, though immunogenicity and off‑target distribution require further study. Conclusion:αCD163/LNP‑FAPCAR enables in situ generation of CAR‑macrophages that selectively eliminate FAP+ activated HSCs, reprogram macrophages toward reparative MMP12+ phenotypes, and reverse liver fibrosis in preclinical models, supporting further translational and safety evaluation. Music:Enjoy the music based on this article at the end of the episode. Article title:mRNA‑laden LNP‑enabled in situ CAR‑macrophage alleviates liver fibrosis via inhibiting activated HSCs and modulating the immune microenvironment First author:Huang X Journal:Proceedings of the National Academy of Sciences (PNAS) DOI:10.1073/pnas.2534673123 Reference:Huang X, Wang J, Hao J, et al. mRNA‑laden LNP‑enabled in situ CAR‑macrophage alleviates liver fibrosis via inhibiting activated HSCs and modulating the immune microenvironment. Proc. Natl. Acad. Sci. U.S.A. 2026;123(22):e2534673123. doi:10.1073/pnas.2534673123. Published May 29, 2026. License:This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/ Support:Base by Base – Stripe donations: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00 Official website https://basebybase.com On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics. Episode link: https://basebybase.com/episodes/in-situ-car-macrophage-liver-fibrosis QC:This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-06-09. QC Scope:- article metadata and core scientific claims from the narration- excludes analogies, intro/outro, and music- transcript coverage: Audited the transcript sections detailing αCD163/LNP-FAPCAR design, CAR-M macrophage generation in vivo, in vitro phagocytosis/cytotoxicity, in vivo fibrosis outcomes, scRNA-seq SAM/MMP12 reprogramming, human macrophage applicability, and safety considerations.- transcript topics: CD163-targeted LNPs delivering FAPCAR mRNA; CAR-M macrophage architecture (CD3zeta with CD28); In vitro phagocytosis and cytotoxicity against FAP+ cells; Syk/Myd88/NF-kB signaling and MMP12 induction; In vivo mouse liver fibrosis models and outcomes; Biodistribution and persistence of αCD163/LNP-FAPCAR QC Summary:- factual score: 10/10- metadata score: 10/10- supported core claims: 7- claims flagged for review: 0- metadata checks passed: 4- metadata issues found: 0 Metadata Audited:- article_doi- article_title- article_journal- license Factual Items Audited:- Ta...