“…A digital twin is a computer replica of a real-life system [e.g., cells [45], tissues [46], or even natural environment [47]], which allows us to integrate real-time and historical data and information about their functionality with the goal of making predictions about their future. This concept, which initially emerged in 1960's in the engineering field [48,49], is not always very clear, mainly due to the interpretation of the connection between the data and the mathematical model. In Figure 2 we summarize the three sub-categories proposed by Kritzinger et al [50] based on the level of data integration, while adapting them to biological systems [51]: (a) in a digital model, the data between the biological object and the digital object is exchanged manually; (b) in a digital shadow the data flow from the biological object to the digital object is automatic, while The diagram shows a caricature description of various cell-cell interactions (at cell/tissue levels) and a zoom-in on a single cell and protein dynamics inside this cell (at molecular-level), to emphasize the multi-scale aspect of some of these biological digital objects.…”