Enhancing pre-clinical research with simplified intestinal cell line models.

Two-dimensional culture remains widely employed to determine the bioavailability of orally delivered drugs. To gain more knowledge about drug uptake mechanisms and risk assessment for the patient after oral drug admission, intestinal in vitro models demonstrating a closer similarity to the in vivo situation are needed. In particular, Caco-2 cell-based Transwell® models show advantages as they are reproducible, cost-efficient, and standardized. However, cellular complexity is impaired and cell function is strongly modified as important transporters in the apical membrane are missing. To overcome these limitations, primary organoid-based human small intestinal tissue models were developed recently but the application of these cultures in pre-clinical research still represents an enormous challenge, as culture setup is complex as well as time- and cost-intensive. To overcome these hurdles, we demonstrate the establishment of primary organoid-derived intestinal cell lines by immortalization. Besides exhibiting cellular diversity of the organoid, these immortalized cell lines enable a standardized and more cost-efficient culture. Further, our cell line-based Transwell®-like models display an organ-specific epithelial barrier integrity, ultrastructural features and representative transport functions. Altogether, our novel model systems are cost-efficient with close similarity to the in vivo situation, therefore favoring their use in bioavailability studies in the context of pre-clinical screenings.

Assessing cell migration in hydrogels: An overview of relevant materials and methods.

Cell migration is essential in numerous living processes, including embryonic development, wound healing, immune responses, and cancer metastasis. From individual cells to collectively migrating epithelial sheets, the locomotion of cells is tightly regulated by multiple structural, chemical, and biological factors. However, the high complexity of this process limits the understanding of the influence of each factor. Recent advances in materials science, tissue engineering, and microtechnology have expanded the toolbox and allowed the development of biomimetic in vitro assays to investigate the mechanisms of cell migration. Particularly, three-dimensional (3D) hydrogels have demonstrated a superior ability to mimic the extracellular environment. They are therefore well suited to studying cell migration in a physiologically relevant and more straightforward manner than in vivo approaches. A myriad of synthetic and naturally derived hydrogels with heterogeneous characteristics and functional properties have been reported. The extensive portfolio of available hydrogels with different mechanical and biological properties can trigger distinct biological responses in cells affecting their locomotion dynamics in 3D. Herein, we describe the most relevant hydrogels and their associated physico-chemical characteristics typically employed to study cell migration, including established cell migration assays and tracking methods. We aim to give the reader insight into existing literature and practical details necessary for performing cell migration studies in 3D environments.