Abstract
Three-dimensional (3D) cultures are increasing in use because of their ability to represent in vivo human physiology when compared to monolayer two-dimensional (2D) cultures. When grown in 3D using scaffold-free agarose hydrogels, MCF-7 human breast cancer cells self-organize to form directionally-oriented microtissues that contain a luminal space, reminiscent of the in vivo structure of the mammary gland. When compared to MCF-7 cells cultured in 2D monolayer culture, MCF-7 microtissues exhibit increased mRNA expression of luminal epithelial markers keratin 8 and keratin 19 and decreased expression of basal marker keratin 14 and the mesenchymal marker vimentin. These 3D MCF-7 microtissues remain responsive to estrogens, as demonstrated by induction of known estrogen target mRNAs following exposure to 17β-estradiol. Culture of MCF-7 cells in scaffold-free conditions allows for the formation of more differentiated, estrogen-responsive structures that are a more relevant system for evaluation of estrogenic compounds than traditional 2D models.
Highlights
There is a large backlog of compounds for which adequate safety information is lacking, due largely to the time-intensive and expensive nature of animal-based toxicity testing [1]
When cultured in a scaffold-free, non-adhesive agarose hydrogel system, MCF-7 breast carcinoma cells derived in our lab self-assemble and organize into microtissue structures with luminal spaces surrounded by 1–2 epithelial cell layers, in contrast with the typical 2D morphology which consists of cells growing in a cobblestone-like pattern
The luminal structure of the MCF-7 microtissues shares features with both the in vivo morphology of the normal adult breast epithelium that has been previously described [36] and the mammary acini formed by normal MCF-10A cells grown in Matrigel [15]
Summary
There is a large backlog of compounds for which adequate safety information is lacking, due largely to the time-intensive and expensive nature of animal-based toxicity testing [1]. In vitro systems have traditionally relied on cells cultured as a monolayer on plastic substrates, in stark contrast to the cell- and extracellular matrix-dense tissues in vivo. To address this gap, recent work has focused on the use of human cells and cell lines in physiologically relevant cell culture systems, including microfluidic on-chip models [2,3,4], 3-dimensional (3D) scaffolded, extracellular matrix-based models [5,6,7,8], and scaffold-free models [9, 10]. Scaffolded models using laminin or collagen have been used for 3D cultures; several cell types have been shown to exhibit
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