Research Program
Cellular Microdynamics

Project #
CM2

Participating Faculty:	Michael Shuler, William Shain
NBTC Students/Postdocs:	Hui Xu, J. Frampton
Other Students/Postdocs:	G. McAuliffe, J. Sung

Objectives
Our goal is to couple micro and nanofabrication techniques with cell cultures to predict toxicology and efficacy of pharmaceuticals. Our cell culture analogs (CCA) containing interconnected cell cultures are constructed to mimic pharmacokinetic models of human. Together the Shain-Shuler group have worked on blood-brain-barrier (BBB) models, and Shuler has worked with R.P. Glahn (USDA-ARS) on GI tract models. These barrier models are to be coupled with systemic or “body” models (e.g. liver-lung-fat-other tissue) to provide a detailed prediction of dynamic response of humans to exposure to drugs. Associated studies have focused on using the CCA system to evaluate potential combination therapies for cancer.

Methods
The basic approach to design and operation of the systemic CCA model has been published by us in Biotechnol. Prog. 20:316-323; 338-345; 590-597 (all in 2004). These devices were all fabricated in silicon. We are particularly interested in coupling our systemic CCA with “barrier” modules; in particular, the gastro-intestinal (GI) tract and the blood brain barrier (BBB). We are using hydrogel (modified alginate) co-cultures to build BBB mimics and membrane based supports for co-cultures to mimic the GI tract.  We perform experiments to determine adsorption-distribution-metabolism-elimination-toxicity characteristics of drug or chemical mixtures. New studies for the toxicity of nanoparticles has been initiated using fluorescent carboxylated polystyrene particles (50 to 200nm) in size. We are also using physiologically-based pharmacokinetic models to design appropriate CCA experiments and as a basis for comparison to animal/human response. We are also developing optical techniques to monitor the response of multiple CCA’s. Tissue impedance microscopy is used to characterize 3-D cell-hydrogel mimics of the brain.

Summary
The triculture of epithelial, goblet, and M cells that we have developed may be the most realistic biological model of the GI tract available. We have used this model to show that both 50nm and 200nm carboxylated polystyrene particles interfere with iron transport across the GI tract, but by different mechanisms. These studies are among the first to examine potential chronic side-effects of oral exposure to nanoparticles. We are also completing initial studies on integration of the GI tract model with a body module and systemic circulation.

Our neural tissue model using hydrogels (modified alginates) and astroglial, neuronal, and endothelial cells have progressed towards more realistic models of brain tissue and blood brain barrier. The 3-D hydrogel cultures of astroglial cells has been used successfully as a model to evaluate microfabricated neural probes.

The CCA body modules are under development for application to colon cancer treatment with drug combinations and for evaluation of response to endocrine disruptors. Optical techniques to monitor cells in multiple chambers on multiple devices have been developed. Potential synergistic interactions of drugs to treat multidrug resistant cancer have been discovered.

Accomplishments

• The micro CCA using realistic doses predicts synergistic interaction of two multidrug resistance (MDR) suppressing compounds (cyclosporine and nicardipine) on selectively reducing growth of MDR resistant cancer in the presence of the chemotherapeutic doxcrubicin without increased toxicity to other tissues.
• Improved GI tract model with epithelial, goblet, and M cells shows that both carboxylated polystyrene particles at 50 and 200 nm reduce iron transport from the gut to the systemic circulation.  The 50 nm particles interfere with diffusional iron transport and the 200 nm interfere with vesicle-mediated iron transport.
• An alginate-RGD hydrogel using various concentrations of astroglial cells was shown to be a good model for evaluating potential reactive cell responses to microprobes in the brain through measurement of electrochemical impedence.