Suppression of FcεRI-evoked Degranulation in RBL-2H3 Cells on Gelatin Methacryloyl Hydrogel

Cell-extracellular matrix (ECM) interactions play multiple roles in developmental, physiological, and pathological processes. ECM stiffness substantially affects cellular morphology, migration, and function. In this study, we investigated the effect of ECM comprising gelatin methacryloyl (GelMA) on the activation of rat basophilic leukemia (RBL-2H3) cells, a model mast cell line. Maintenance of intracellular Ca²⁺ concentration ([Ca²⁺]_i) elevation and subsequent degranulation, evoked by crosslinking the high-affinity IgE receptors (FcεRI), were significantly suppressed in RBL-2H3 cells on collagen-coated GelMA hydrogel than those on collagen-coated glass dishes and plastic wells. Thapsigargin and phorbol myristate acetate caused sustained [Ca²⁺]_i increase and degranulation to a similar extent in cells on both GelMA hydrogel and plastic wells/glass dishes. F-actin was clearly accumulated along the periphery of RBL-2H3 cells in plane attached to glass, but not GelMA hydrogel, suggesting that the loose actin cytoskeleton of RBL-2H3 cells on GelMA hydrogel caused suppressive degranulation through unstable FcεRI aggregation.