Coculture Systems

Combining cell types in vitro by coculturing is one way to increase the long-term viability as well as complexity of in vitro models, and to this end, cocultures of intestinal epithelial cells with myofibroblasts, immune cells, or bacteria have been utilized to model the interactions between epithelial cells and others within the GI tract. Susewind et al. (2015) investigated the effect of coculturing Caco-2 cells 

FIGURE 62 Transepithelial electrical resistance (TEER) of some commonly used gastrointestinal cell lines. Representative gastrointestinal cell lines were cultured on transwell filters with appropriate growth media. TEER values were obtained with REMS by World Precision Instruments (Sarasota, FL) after 7 days in culture. 

Or at least something closer to resembling the complexity of the gastrointestinal tract 

FIGURE 16.3 Challenges with in vitro models of the GI tract. Successive improvements in cell isolations and culture and understanding the molecular mechanisms of differentiation and microfluidic technology are improving our abihty to model the Gl tract in vitro. 

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Wyman, A., et. al., 2,3,7,8-Tetrachlorodibenzo-p-dioxin does not directly alter the phenotype of maturing B cells in a murine coculture system, Toxicol. Appl. Pharmacol., 180, 164,2002. 

Guillouzo et al. (1988) developed a coculture system of rat or human hepatocytes with rat liver epithelial cells that maintains the hepatocytes in a differentiated state for extended periods of time, thereby allowing studies involving chronic treatment with the test substance to be conducted. Primary cultures of hepatocytes can therefore provide a useful model for short- and long-term studies involving the safety assessment of xenobiotics. 

However, this systems need further evaluation. For an industrial environment coculture systems need to be robust and reliable being at the same time easy to handle. On the other hand, convincing advantages have to be shown to change the monolayer system to a coculture model or to change the cell system used. In many companies CACO-2 cells are used since many years and an immense data base is available. 

Tukov FF, Maddox JF, Amacher DE, Bobrowski WF, Roth RA, Ganey PE. Modeling inflammation-drug interactions in vitro A rat Kupffer cell-hepatocyte coculture system. Toxicol In Vitro. 2006 20(8) 1488-1499. 

Three days later, replace the medium by a BBB-inducing medium, developed in collaboration with Cellial Technologies (Lens, France). This conditioned medium is harvested 48 h after refreshing the original coculture system medium and is frozen until further use. 

In a recent study, we tested the abihty of the hES ceU-derived cardiomyocytes to integrate structurally and functionally with host cardiac tissue both in vitro and in vivo [67]. Initially, the ability of the hES cardiomyocytes to form electromechanical connections with primary cardiac cultures was assessed using a high-resolution, in-vitro coculturing system (Eig. 12.3a). The contracting areas within the EBs were dissected and added to primary neonatal rat cardiomyocyte cultures. Within 24 hours of grafting it was possible already to detect microscopically, in all 22 cocultures studied, synchronous mechanical activity (as impressively shown in a video on the sup-... 

Satsu, H., Yokoyama, T., Ogawa, N., Fujiwara-Hatano, Y, and Shimizu, M., The changes in the neuronal PC 12 and the intestinal epithelial Caco-2 cells during the coculture. The functional analysis using an in vitro coculture system, Cytotechnology, 35, 73, 2001. 

A recently described multicellular model that may offer promise is the formation of liver buds from pluripotent stem cells cultured with endothelial cells and mesenchymal stem cells (Takebe et al., 2013). This coculture system self-organizes into a 3D bud of cells with a complex vasculature and shows improved hepatic function compared to 2D controls. Despite this, the authors report a lack of biliary cell formation suggesting that this model, while being a step forward, requires independent reproduction and further development before fully recapturing the complex architecture of the liver. 

Apart from these in vivo applications, a coculture system on hepatic cells was also reported for assaying the bioactivity of a procyanidin extract. In this report, different procyanidin metabolites were identified, these being catechin and epicatechin in its sulfate forms methyl-catechin and methyl-epicatechin in its sulfate forms epicatechin glucuronide, methyl-catechin, and methyl-epicatechin in its glucuronide forms and the aglycones catechin and epicatechin, epicatechin in its gallate forms, dimer and trimer [38]. 

Coculture of astrocytes with cerebellar neurones from 6-days old mice enhanced the uptake of glutamate by astrocytes (Brown 1999). Inhibition of glutamate uptake in a coculture system led to death of cerebellar cells. This toxicity could be inhibited by the hf-methyl-D-aspartate receptor antagonist, MK801. However, in the presence of the glutamate uptake inhibitor, there was no increase in glutamate in the cultures compared to when the neurones were not cocultured. 

One of the main disadvantages of using pure culture for the production of PHB includes the high cost of the pure substrates utilized and the cost of sterile precultivation of the bacteria utilized as well as the sterile operation of the final production process. Mixed or coculture systems are widely used in several fermentation processes. There are many fermentation systems, where microorganisms assimilate one substrate and convert it to an intermediate metabolite which is converted from other microorganisms to metabolite-target product. Mixed or coculture systems will serve as an attractive addition to traditional pure culture-based technology for the production of PHB. 

Polyurethane coculture systems for liver tissue engineering... 

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