Engineering an organoid culture system for enhanced murine and human hematopoietic stem and progenitor cell self-renewal and expansion

Developing a biomimetic culture system is crucial for the efficient maintenance and expansion of rare hematopoietic stem and progenitor cells (HSPCs)<i>in vitro</i>. This advancement can significantly enhance the application of HSPC-based transplantation therapies and support the manufacturing of bone marrow (BM) organoids. Traditional two-dimensional culture systems fall short in replicating the interactions between cultured cells and the hematopoietic niche, resulting in excessive reactive oxygen species (ROS) production and triggering HSPC differentiation. In response, we have developed an innovative three-dimensional (3D) culture system using a novel composite hydrogel, GelMA-PVA-TSPBA (GelMA-P-T), which offers excellent biocompatibility and ROS-scavenging properties. When murine and human embryonic stem cell (hESC)-derived HSPCs were cultured in this new hydrogel, they exhibited low ROS levels and showed enhanced self-renewal and expansion capabilities. Importantly, incorporating niche-related cells into the composite hydrogel created a 3D engineered BM microenvironment that significantly improved the self-renewal and expansion of HSPCs. Additionally, the biomimetic niche comprising GelMA-P-T and various stromal cells effectively inhibited the differentiation of murine and hESC-derived HSPCs. Mechanistically, compared with GelMA, the low ROS microenvironment fostered by GelMA-P-T significantly enhanced mitochondrial function in HSPCs, supporting the expression of HSPC-related genes and inhibiting blood cell differentiation. Our findings suggest that the GelMA-P-T-based biomimetic culture system has the potential to advance the clinical application of expanded HSPCs and accelerate the development of BM organoid technology.