Unige iGEM 2019



The reduction of animal testing by alternative in vitro methods is now being encouraged by the World Health Organization and the US Food and Drug Administration (FDA). However, reducing our reliance on animal models is an immense challenge because current in vitro cell cultures poorly reflect the physiological organization of tissues, nor the complexity of multi-organ animals. These facts directly contribute to the low success rates for drug testing because a high proportion (~98%) of drugs that appear efficacious in vitro do not succeed during in vivo trials. Therefore, we believe there is an urgent need to improve in vitro drug testing to better simulate the in vivo physiology of animal models and humans.



Encapsulated cell spheroids for high relevance cell culture

Tissues and organs naturally grow in three dimensions (3D), and this spatial organization is required for certain physiological processes. Encapsulation of cells allows them to form spheroids, which are 3D-organized multicellular structures. Instead of standard spheroids that can reach unsupportable sizes in vitro due suboptimal oxygen and nutrient diffusion, alginate-based capsules can maintain cell spheroids at sizes that retain the featurs of normal in vivo perfused tissue. In the human body, organs communicate with each other via secreted molecules that circulate in the blood, meaning that many different types of cells never come into physical contact with each other. For example, liver cells that metabolize drugs never contact cancer cells at distal sites. Cell encapsulation can therefore be used to recapitulate the compartmentalization of different cell types, while free movement of drugs or soluble biomolecules can still occur between all cell spheroids because the alginate capsule is porous.


Labeling the capsule for cell type recognition

Alginate molecules can be covalently labeled with different fluorescent proteins, or 'fluorophores'. Fluorescent microscopy can be used to identify different cell types in a mixed co-culture if the each cell type was encapsulated using different fluorescent-alginate capsule. Therefore, responses to drugs or other stimuli can be measured simultaneously in multiple cell types, in the same test.


Tracking biological activities with fluorescent reporters

Fluorescent reporter proteins can be used to quantify the levels of different biological activities. The expression of these proteins is under the control of a transcription factor regulated by a biological activity (hormonal response, xenobiotic response,...), or their processing or stability depends on a biological process (apoptosis, proliferation,...). Genetic engineering of cells with fluorescent reporters allows the detection and measurement of diverse biological activities in encapsulated cells.


Fluorescent combinations for multiplexing

Combination of cell type recognition with fluorescent alginate capsules, and biological activity detection with fluorescent reporter cells allows the simultaneous and individual measurements of multiple biological activities in multi-cell type co-cultures. Multiplexed data acquisition and analysis are performed by a high-content screening microscopy method. Up to 16 different capsule-reporter fluorescent combinations can be analyzed at the same time in a single well.


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