High-throughput fabrication of hepatic cell clusteroids with enhanced growth and functionality for tissue engineering applications†
Culturing of cells as three-dimensional (3D) clusters can enhance in vitro tests for basic biological research as well as for therapeutics development. Such 3D culture models, however, are often more complicated, cumbersome and expensive than two-dimensional (2D) cultures. Current methods for the preparation of tissue spheroids require complex materials, involve tedious facilities and are generally not scalable. We report a novel inexpensive and up-scalable method for the preparation of large quantities of viable cell clusters (clusteroids) of hepatocytes (Hep-G2). The method has a high throughput potential and is based on an aqueous two-phase system (ATPS) of stable water-in-water (w/w) Pickering emulsions, formed of dextran (DEX) drops and poly ethylene oxide (PEO) continuous phase stabilized with whey protein particles. This system enabled the rapid fabrication of cell clusteroids from Hep-G2 cells. Here, the interfacial tension of the aqueous phase in the emulsion droplets, where the cells partition preferentially, is used to wrap the cells in separate compartments, and then the droplets are shrank by changing the balance of ATPS, thus rapidly driving the cells from larger and loosely packed DEX drops to mostly spherical clusters. Cell–Cell adhesion was strongly promoted within the w/w Pickering emulsion droplets which helped the formation of the 3D clusteroids. These were collected after subsequent dilution of the emulsion with culture media. The collected hepatic clusteroids were incorporated into an alginate hydrogel in media to study their proliferation and the cell function compared with individual cells under the same conditions. Our results confirmed that urea and albumin production, which are both linked to hepatocyte cell function, was strongly reinforced in the clusteroid based tissues compared to the one formulated with individual cells. This methodology could potentially extend the w/w emulsion cell clustering platform in tissue generation and preparation of large quantities of organoids for drug tests and replacement of animal models.