Development of three-dimensional cell culture bioprocesses

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Applications of immobilized cell culture range from the stabilization of probiotic bacteria to tissue engineering and cellular therapy. The 3D organisation of the cells within the materials affects nutrient and waste product concentration gradients, and hence product performance. In addition, manufacturing complex 3D constructs while optimizing both cellular function and material properties is currently challenging. The long-term goal of the proposed research program is to develop bioprocesses to scale up the production of cells in complex 3D environments. The 5-year goal of this program is to develop methods to encapsulate pancreatic cell clusters in hydrogel beads such as alginate beads. Alginate is a negatively charged linear polysaccharide used in clinical trials of encapsulated pancreatic islet transplantation to treat diabetes, and is broadly used in several other cellular therapy applications. Alginate emulsification and internal gelation is a simple and robust alginate bead production method that I have previously adapted to mammalian cell immobilisation. The process is highly scaleable, but produces beads with a broad bead size distribution, which leads to between-bead differences in mechanical properties and performance. So far, the optimisation of cell survival and bead properties as a function of process parameters has relied mainly on empirical observations. To obtain monodisperse beads with well-controlled mechanical properties and effects on the encapsulated cells, the proposed approach is to develop a novel microchannel emulsification-based cell encapsulation process. The short-term objectives are to (1) model hydrogel bead formation kinetics, (2) develop and (3) optimise a microchannel emulsification-based process for cell encapsulation, and then (4) test the effect of the resulting bead properties on pancreatic cell function. These novel cell immobilisation strategies represent a significant advance towards scaleable three-dimensional cell culture in hydrogels with well-controlled physical properties. These novel bioprocesses could be applied to other cell types that require three-dimensional scaffolds to maximize desired biological functions. This research program addresses key limitations of cell immobilisation bioprocesses.