Allometric Scaling and Cell Ratios in Multi-Organ in vitro Models of Human Metabolism.

Clear input Limits Advanced Journal list Help Journal List Front Bioeng Biotechnol v.2; 2014 PMC4269269 Logo of frontbb Front Bioeng Biotechnol. 2014; 2: 74. Published online 2014 Dec 17. doi: 10.3389/fbioe.2014.00074 PMCID: PMC4269269 Allometric Scaling and Cell Ratios in Multi-Organ in vitro Models of Human Metabolism Nadia Ucciferri,1,2 Tommaso Sbrana,2 and Arti Ahluwalia1,2,* Author information ? Article notes ? Copyright and License information ? Go to: Abstract Intelligent in vitro models able to recapitulate the physiological interactions between tissues in the body have enormous potential as they enable detailed studies on specific two-way or higher order tissue communication. These models are the first step toward building an integrated picture of systemic metabolism and signaling in physiological or pathological conditions. However, the rational design of in vitro models of cell-cell or cell-tissue interaction is difficult as quite often cell culture experiments are driven by the device used, rather than by design considerations. Indeed, very little research has been carried out on in vitro models of metabolism connecting different cell or tissue types in a physiologically and metabolically relevant manner. Here, we analyze the physiological relationship between cells, cell metabolism, and exchange in the human body using allometric rules, downscaling them to an organ-on-a-plate device. In particular, in order to establish appropriate cell ratios in the system in a rational manner, two different allometric scaling models (cell number scaling model and metabolic and surface scaling model) are proposed and applied to a two compartment model of hepatic-vascular metabolic cross-talk. The theoretical scaling studies illustrate that the design and hence relevance of multi-organ models is principally determined by experimental constraints. Two experimentally feasible model configurations are then implemented in a multi-compartment organ-on-a-plate device. An analysis of the metabolic response of the two configurations demonstrates that their glucose and lipid balance is quite different, with only one of the two models recapitulating physiological-like homeostasis. In conclusion, not only do cross-talk and physical stimuli play an important role in in vitro models, but the numeric relationship between cells is also crucial to recreate in vitro interactions, which can be extrapolated to the in vivo reality.