Three-dimensional co-culture model employing silica nonwoven fabrics to enhance cell-to-cell communication of paracrine signaling between hepatocytes and fibroblasts.

The realization that soluble factors secreted by heterotypic cells play an importanta role in paracrine signaling, which facilitates intercellular communication, enabled the development of physiologically relevant co-culture models for drug screening and the engineering of tissues, such as hepatic tissues. The most crucial issues confronting the use of conventional membrane inserts in segregated co-culture models that are used to study paracrine signaling between heterotypic cells have been identified as long-term viability and retention of cell-specific functions, especially when isolated primary cells are used. Herein, we present an in vitro segregated co-culture model consisting of a well plate incubated with rat primary hepatocytes and normal human dermal fibroblasts which were segregated using a membrane insert with silica nonwoven fabric (SNF) on it. SNF, which mimics a physiological environment much more effectively than a two-dimensional (2D) one, promotes cell differentiation and resultant paracrine signaling in a manner that is not possible in a conventional 2D culture, owing to high mechanical strength generated by its inorganic materials and interconnected network structure. In segregated co-cultures, SNF clearly enhanced the functions of hepatocytes and fibroblasts, thereby showing its potential as a measure of paracrine signaling. These results may advance the understanding of the role played by paracrine signaling in cell-to-cell communication and provide novel insights into the applications of drug metabolism, tissue repair, and regeneration.