3D microtissues are superior to mono-layers of cells grown in 2D because 3D better replicates tissue function and also replicates the natural microenvironments of in vivo tissues and organs. 3D microtissues replicate gradients of nutrients, metabolic waste products, and oxygen better than a thin layer of 2D cells. 3D also replicates the cellular barriers and obstacles to drug diffusion that are important for a drug’s efficacy. It is well understood that the efficacy of a drug depends on its ability to reach its target at the desired concentration. And, drug concentration within a tissue is limited not only by the ability of the drug to enter and transport through the tissue, but also by how fast it is eliminated from the tissue, both of which are controlled by transport pumps of the ATP-Binding Cassette family (ABC-transporters). The disposition of a large number of drugs is modulated by Pgp and efflux transporters since their substrates include a broad range of chemically diverse substrates used for a variety of therapeutic applications. This thesis set out to investigate three specific aims: (1) to develop an assay to quantify fluorescence in 3D microtissues using wide-field fluorescent microscopy, (2) to quantify the effect of transport pump inhibition on the uptake, transport, and penetration through 3D microtissues, and (3) to quantify the elimination rate of transporter substrates out of 3D microtissues. These objectives were created so that ABC-transporters, here specifically P-glycoprotein, could be studied in a 3D environment that more closely replicates the in vivo environment to further define their role in the complex processes of multi-drug resistance and drug absorption, distribution, metabolism, excretion, and toxicity (ADME-Tox). Thus, we addressed a need for new quantitative in vitro screening assays to better predict the in vivo actions of new drug candidates and their elimination from specific tissues or organs, using 3D microtissues, to better mimic the tissue geometries and complexities of the body.
Achilli, Toni-Marie,
"Quantifying Uptake, Transport, and Elimination in 3D Self-Assembled Microtissues"
(2014).
Biomedical Engineering Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z03T9FKP
