3D Model Replicating the Intestinal Function to Evaluate Drug Permeability

Animal models are essential in drug development but present many concerns in the practical and ethical sense. To avoid the unnecessary use of animals other models are used in the beginning of any scientific discovery, the in vitro models. The relevance of in vitro cell based culture models for studying intestinal drug absorption and transcytosis during early stages of drug development is undeniable. Several in vitro co-culture models have been described for this purpose, however excluding the integration of the complex intestinal architecture and neglecting different physiological mechanisms involved in the drug transport. 2-D cell cultures are the current standard, but despite their widely use, they no longer are considered the most trustworthy in vitro models since they do not mimic many aspects that happen in vivo. The simulation of a complete microenvironment capable of mimicking the intestinal mucosa requires therefore further investigation, particularly focused in addressing the abovementioned unmet needs. 3D models came as bridge between the in vitro and in vivo models. These models are proven to be influential of the drug effect in cells, being the most adequate to mimic the live tissue especially in drug development. Supported by the great amount of studies using simple and reductionist co-culture monolayers, and pushing forward an innovative model previously reported by our group, the present study aims to describe a sophisticated and highly reproducible in vitro 3D co-culture intestinal model. Here, the components are assembled in a multistage process into Transwell filters by co-culturing human colon carcinoma Caco-2 and mucusproducing HT29-MTX cells over a layer of collagen embedding intestinal myofibroblasts (CCD-18Co). The 3D co-culture intestinal model described herein represents a particularly powerful and versatile tool that recapitulates the intestinal functioning regarding mucus production, tightness of the different cell types, and the 3D architecture, bridging the gap between simple monolayer cultures of epithelial cells and the complex in vivo physiological conditions. Importantly, it shows tremendous potential in predicting intestinal absorption of orally administered drugs when delivered alone, or encapsulated into micro- and nanosystems, the current leading force of pharmaceutical technology research.