Oxidized Cellulose Nanofiber Hydrogels for 3D Airway Spheroids and Influenza Infection Modeling

Micro‐physiological systems (MPS) that recapitulate tissue architecture and immune competence are urgently needed to model respiratory viral infections and accelerate antiviral discovery. Here, we create an airway spheroid‐based MPS supported by an oxidized cellulose nanofiber (OCNF) hydrogel, which provides a hydrated, extracellular matrix (ECM) mimetic nanofibrillar microenvironment and supports stable long‐term 3D culture. Airway epithelial‐like spheroids are generated either from Calu‐3 cells alone or as immunocompetent co‐culture spheroids incorporating polarized THP‐1 macrophage‐like cells to capture epithelial‐immune crosstalk. The OCNF platform promotes rapid spheroid self‐assembly within 6 days and preserves structural integrity for ≥ 20 days, allowing longitudinal interrogation of influenza A virus replication and host innate immune responses. Notably, the model reveals that human bone marrow‐derived mesenchymal stem cells (MSCs) exert potent antiviral activity, significantly reducing influenza infection through activation of interferon (IFN)‐associated pathways, including MX1, OAS1, and STAT1. Together, this OCNF hydrogel‐enabled airway spheroid MPS provides a scalable and reproducible test‐bed for mechanistic studies and preclinical evaluation of antiviral interventions and establishes an in vitro platform toward personalized patient‐relevant respiratory infection models.