Hollow fiber bioreactors
such as the Quantum Cell Expansion Bioreactor consist of a bundle of porous membrane capillaries that are integrated in a plastic cartidge. The cells are thereby expanded in the extracapillary space (around the capillaries) and are able to grow three-dimensionally. With the hollow fibers, nutrients from the aerated medium can reach the cells (intracapillary space) and waste products can be removed. This allows the generation of high cell densities (HCD) and the continuous secretion of protein-based products in the extracapillary space where the shear forces are low. The main disadvantages of the hollow fiber bioreactor are the limited oxygen transport and the limited scale-up capability 1.