Stem cell expansion in a fluidised bed bioreactor for accelerated osseointegration of bone substitute material

The aim of this work is to enable the culturing of human stem cells within a porous bioceramic scaffold in a novel fluidised bed bioreactor. As such, the populated scaffold would be superior to the current synthetic bioceramic bone graft materials commercially available. The presence of a viable cell population will promote more rapid osseointegration thus accelerating the healing process. Particles of hydroxyapatite / tricalcium phosphate (4-6mm in diameter) have been fluidised successfully. The results combined with data from terminal velocity experiments and fundamental theory of fluidisation, have been used to develop a CFD model of the bioreactor in FLUENT. This model utilises a combination of the Eulerian multiphase model and the dense discrete phase model to calculate the velocity, pressure drop and shear stress within the bioreactor allowing control of its operation. Tests to establish the shear stress in relation to attachment and detachment of a cell line, using a purpose-built flow chamber, will enable the final design of the fluidised bed to be optimised in this FLUENT model. This analysis will inform the next stage of the project where suitable conditions will be derived to seed and culture a cell line within the fluidised bed. This model has the scope to be adapted to encompass the differing requirements of a range of cell lines in conjunction with bone graft material of different geometries, compositions and properties.