Novel strategies to expand and engineer hematopoietic stem cells.

Abstract

Hematopoietic stem cell (HSC) transplantation is a lifesaving therapy for hematologic diseases, but its broader application remains constrained by challenges in sourcing, manipulating, and reliably expanding functional HSCs. In this review, we discuss strategies to expand and engineer HSCs by recreating essential aspects of the bone marrow niche. These include defined cytokine cocktails, small molecule modulators, stromal co-culture systems, and biomaterials that promote self-renewal while limiting differentiation. We highlight advances in three-dimensional organoid models and microfluidic platforms that better support long-term repopulating cells and reflect native microenvironments. In parallel, progress in gene delivery platforms, including both viral and nonviral approaches, is enabling more efficient and targeted modification of HSCs for therapeutic use in genetic disorders such as sickle cell disease and β-thalassemia. While these tools have advanced significantly, significant hurdles remain in scaling, preserving stem cell identity, and reducing culture-induced stress. Continued refinement of biomimetic systems and genome engineering technologies will be central to expanding the clinical utility of HSC-based therapies.