What Can an In Vitro Model Establish? A Claim-Specific Validation Framework for Neural and Bioelectronic Interfaces

Neural and bioelectronic interfaces are evaluated using electrochemical systems, cell cultures, organoids, tissue preparations and computational models. These platforms establish different things, yet evidence of technical performance and biological response can be extended without specifying the inference connecting them. This narrative methodological review develops a claim–model correspondence framework linking the scientific claim, required causal or predictive relation, model and context, endpoint, comparator and admissible inference. It applies the framework to eight claim classes: material transformation, cellular response, interface response, neural function, barrier transport, operation–biology coupling, architecture feasibility and clinical consequence. Published examples show why material loss does not establish tissue exposure, neural activity does not establish therapeutic benefit, and one barrier property does not validate every transport mechanism. Conversely, added biological complexity can be essential when it supplies a required relation, and externally benchmarked models can support prediction without reproducing an entire organism. The synthesis separates biological complexity from inferential adequacy and measurement coverage from translational validity. It identifies three remediable gaps: missing model relations, insufficient endpoint correspondence and unsupported transfer to a target context. The contribution is a domain-specific operationalisation of established context-of-use principles, not a new general theory of validation. A prospective comparison with existing guidance is proposed to test whether the framework improves experimental design and claim calibration; that assessment has not been performed.