A) The lineage hierarchy of hematopoietic stem cells, with long-term and short-term hematopoietic stem cells grouped as HSCs (blue), Multipotent Progenitors (orange), and Common Myeloid Progenitors (lavender). B) The relative population of HSC (blue), MPP (orange), CMP (lavender) are shown for single-culture and co-culture at 1:1 and 1:10 (HSPC:MSC), in the Low, Med, and High variants. The height of each subcolumn reflects how much of the total cell population is made up of the specified cell type. The blue columns (HSC) show that the highest percentage of HSCs are found in the single-culture Low variant (1:0), and in the 1:1 co-culture High variant. C) The percentage of HSCs that make up the total hematopoietic cell population, arranged in order of increasing MSC density (1:0, 1:1, 1:10 HSPC:MSC), and in order of increasing hydrogel stiffness (Low, Med, and High). The largest percent of HSC is found in the High variant at a 1:1 seeding ratio and is significantly higher (p<0.05) than all other conditions.