Advances in hPSC expansion towards therapeutic entities: A review

Abstract

For use in regenerative medicine, large-scale manufacturing of human pluripotent stem cells (hPSCs) under current good manufacturing practice (cGMPs) is required. Much progress has been made since culturing under static two-dimensional (2D) conditions on feeders, including feeder-free cultures, conditioned and xeno-free media, and three-dimensional (3D) dynamic suspension expansion. With the advent of horizontal-blade and vertical-wheel bioreactors, scale-out for large-scale production of differentiated hPSCs became possible; control of aggregate size, shear stress, fluid hydrodynamics, batch-feeding strategies, and other process parameters became a reality. Moving from substantially manipulated processes (i.e., 2D) to more automated ones allows easer compliance to current good manufacturing practices (cGMPs), and thus easier regulatory approval. Here, we review the current advances in the field of hPSC culturing, advantages, and challenges in bioreactor use, and regulatory areas of concern with respect to these advances. Manufacturing trends to reduce risk and streamline large-scale manufacturing will bring about easier, faster regulatory approval for clinical applications.

FIGURE 1

Horizontal flow and vertical‐wheel bioreactors used in hPSC expansion. (A) Rotating wall bioreactors (RWBs) continuously rotate along their longitudinal, horizontal axis, creating low shear stress and homogeneous mixing. (B) Vertical‐wheel bioreactors have simultaneous radial and axial mixing, creating uniform hESC aggregates and gentle mixing