Hi

There is no specific guidance by the FDA or guideline by EMA. But some information should be helpful:

https://www.fda.gov/science-research/about-science-research-fda/advancing-alternative-methods-fda

https://www.fda.gov/science-research/fda-grand-rounds/fda-grand-rounds-microphysiological-systems-novel-disease-models-and-drug-development-tools-03092023#event-information

and in general: https://www.fda.gov/search?s=organoid

FDA Definitions

Microphysiological System (MPS):: A microphysiological system uses microscale cell culture platform for in vitro modeling of functional features of a specific tissue or organ of human or animal origin by exposing cells to a microenvironment that mimics the physiological aspects important for their function or pathophysiological condition. MPS design may aim to provide and support cultured cells with physical (e.g., temperature, pH and oxygen)/biochemical/electrical/mechanical (e.g., flow or stretch)/structural/morphological conditions and recapitulate a set of specific properties that define a healthy or diseased organ or tissue function. MPS platforms may comprise mono-cultures, co-cultures of multiple cell types, maintenance of explants derived from tissues/organs, and/or inclusion of organoid cell formations.

Organ-on-a-chip: Organ-on-a-chip is a subset class of microphysiological systems and consists of a miniaturized physiological environment engineered to yield and/or analyze functional tissue units capable of modeling specified/targeted organ-level responses.

Hope it helps

Best regards

Tomasz