@Stephen – My perspective would be that the model would then be caveated for that particular marker. My main reasoning being that it isn’t necessarily a flaw of the model, but a donor variability. It certainly could be a deficit of the model, but that is a large component of why having multiple donors for a given model is so critical. It allows us to account for this variability in response and determine whether it is an outlier or commonality. Additionally, for determining the criteria for a model, that is why organizations such as IQ MPS and others like it are so valuable. You have an independent group that sets a standard to be met that addresses the needs of that particular specialty and researchers on 3D in-vitro systems can then work towards them. With further understanding, the guidelines/requirements can be adjusted and improved upon, but it sets a precedent.