Programmable macromolecule delivery via engineered trogocytosis.

Trogocytosis, the transfer of plasma membrane fragments during cell-cell contact, offers potential for macromolecular delivery but is limited by the uncertain fate of trogocytosed molecules, restriction to membrane cargo and unclear generalizability. Here we demonstrate that donor cells engineered with designed receptors specific to surface ligands can transfer proteins to recipient cells through direct contact. We identified key engineering principles for enhancing transfer and ensuring cargo functionalization, including receptor design, pH-responsive membrane fusion, inducible cargo localization and release, and subcellular translocation. The method is broadly applicable across diverse cell types and operates through a dynamin- and endosome acidification-dependent pathway. Exploiting these findings, we developed TRANSFER, a versatile delivery system with programmable cell type specificity and tunability. TRANSFER can sense multiple ligand inputs, deliver large therapeutic protein cargos and mediate genome editing. The study establishes trogocytosis as a programmable, versatile framework for cell-based macromolecular delivery.