Culturing Potential: advances in ex vivo cell culture systems for haematopoietic cell-based regenerative therapies

Stem-cell derived therapies are an essential pillar in the field of regenerative medicine, utilising stem cell self-renewal and multipotent or pluripotent differentiation capabilities to give rise to functional, specialised cells to repair and restore tissue function. Haematopoietic cell therapies have been pivotal to the development of the regenerative medicine field and continue to hold significant promise enabled by recent technical innovation in cell culture approaches that have expanded their therapeutic potential. The development of novel cell culture protocols that allow for the standardised ex vivo expansion of haematopoietic stem cells (HSCs) has facilitated the exploration of umbilical cord blood allogeneic HSC transplantation. Directed differentiation protocols of HSCs, embryonic stem cells and induced pluripotent stem cells, to selectively produce a desired haematopoietic cell type in a donor-independent manner, has broadened the scope for haematopoietic cell-based regenerative therapy. Furthermore, the integration of genome modification or gene editing with these protocols have allowed for corrective autologous HSC transplantation as well as the ability to confer haematopoietic cells with enhanced or novel therapeutic functions. Despite this, realising large-scale clinical translation remains challenging. Current efforts aim to move towards chemically defined culture systems, improving the efficiency and reproducibility of lineage-specific differentiation with an emphasis on compatibility with genome modification and gene-editing protocols for the scalable production of high-quality, efficacious and safe cellular therapies. In this review, we summarise the key milestones and technical advancements in the field in addition to the outstanding questions to be addressed.