Cellular Layer-by-Layer Coculture Platform Using Biodegradable, Nanoarchitectured Membranes for Stem Cell Therapy

Stem cells are regulated in vivo through interactions with the surrounding microenvironments in a three-dimensional (3D) manner. A coculture of stem cells with desired cell types, which recapitulates the complex in vivo cell–cell communications, has been reported as an effective method to direct stem cell differentiation into specific lineage. However, conventional bilayer coculture systems employ membranes of microscale thickness and low porosity, which limit interaction between cocultured cells for efficient stem cell differentiation. Furthermore, conventional coculture systems require cell-impairing enzyme treatment to harvest the cells from the membranes. Here, we developed a cellular layer-by-layer (cLbL) coculture platform using biodegradable, nanothin, highly porous (BNTHP) membranes. Equipped with more porous and thinner membranes, the cLbL coculture platform better mimicked the in vivo 3D microenvironment and promoted cellular cross-talks between cocultured cells which occurred in nanoscale, resulting in more efficient stem cell differentiation compared to the conventional bilayer coculture systems. Furthermore, biodegradibility, biocompatibility, and highly flexibility of BNTHP membranes enabled conversion of the cell-attached membranes into implantable 3D cell constructs, thus avoiding harmful enzymatic harvesting of the cells. The cLbL platform may be an effective method to induce stem cell differentiation and facilitate cell implantation for stem cell therapy.