3D biofabricated in vitro models as new approach methodologies for animal alternatives

The FDA Modernization Act 2.0 has shifted from animal testing to New Approach Methodologies (NAMs) for preclinical drug development. Three-dimensional (3D) bioprinting has emerged as a premier NAM, capable of fabricating human-relevant complex models with high fidelity. This review surveys the primary bioprinting modalities, including inkjet, extrusion, vat photopolymerization, and their applications in creating functional in vitro models for drug screening and disease modeling. We analyze the operating mechanisms, advantages, and limitations of each technique, from high-resolution inkjet patterning to the rapid, layerless fabrication enabled by volumetric methods. Although challenges regarding regulatory validation, vascularization, and anatomical complexity persist, advanced bioprinting strategies incorporating biochemical cues, cellular diversity, and multi-tissue interactions are paving the way for more predictive and humane therapeutic pipelines. This work outlines the technological landscape and future directions for biofabrication in a post-animal testing era.