Materials design & modification for a three dimensional hollow fibres bioreactor for the production of blood cells

Abstract

One of the World Health Organization’s biggest concerns is meeting blood demand while ensuring safety and despite the efforts of world blood banks, the gap between supply through donations and demand continues to widen (Nolan, 2017). Hence, a practical and cost-effective alternative to conventional blood donation is essential to meet the demand and reduce patient risks. Previous attempts to recruit blood stem cells to produce blood cells in platforms have achieved limited success specifically in areas of cell-platform interaction, perfusion, and cell harvest. The PhD thesis presented here is aimed at bringing the Bone Marrow (BM) mimicry Bioreactor (BR) developed and patented by BioBlood project closer to physiological representation of the natural human BM niche which hosts blood cells production. This is achieved by focusing on modification and optimization of the synthetic materials used in the bioreactor. Firstly, the polyurethane (PU) scaffold which mimics the BM microenvironment and modulates cell expansion and fate. Secondly, the alumina hollow fibres (HF) representing the vascular system of BM which regulate nutrients and cellular constituents while harvesting mature blood cells. To augment PU bio-functionality and optimize signalling/interaction between cells and scaffold, a novel protocol of RGD surface modification of PU was developed targeting enhancing: cell adhesion, cellular infiltration, and differentiation into blood cell lineages. Adhesion of human umbilical stem cells (hUSC) was improved by more than 85% in RGD-modified PU scaffolds, whereas cell penetration was increased by 4-folds. Alumina hollow fibres’ (HF) structural and filtration characteristics, on the other hand, were improved to support a higher yield and purity of harvested RBC through manipulation and optimization of fabrication parameters. HF improved purity of harvested RBC from 30% to 80% and supported a 1.6 fold increase in cellular density when incorporated in a PU-bioreactor. Combining the two optimized materials in the 3D bioreactor (BR) set-up envisioned to support increased production and selective harvesting of clinically relevant quantities of red blood cells.