Engineered Murine HSCs Reconstitute Multi-lineage Hematopoiesis and Adaptive Immunity

Area of Science:

• Stem Cell Biology
• Hematopoiesis
• Immunology

Background:

• Hematopoietic stem cell (HSC) transplantation offers a cure for blood disorders but faces donor limitations and immune rejection.
• Patient-matched embryonic/induced-pluripotent stem cells (ESCs/iPSCs) are a promising alternative source for HSCs.
• Previous attempts using HoxB4 in murine models achieved multi-lineage reconstitution but lacked robust lymphoid engraftment.

Purpose of the Study:

• To engineer functional HSCs from ESCs/iPSCs capable of robust multi-lineage reconstitution and adaptive immunity.
• To overcome the limitations of donor availability and immune-mismatch in HSC transplantation.
• To investigate the gene regulatory networks governing engineered HSC self-renewal and lineage priming.

Main Methods:

• Titrating exposure of HoxB4-expressing ESC-HSCs to Notch ligands.
• Engraftment studies in primary and secondary recipient mice (including immune-deficient models).
• Single-cell gene expression analysis to characterize engineered HSCs post-engraftment.

Main Results:

• Derivation of engineered HSCs that exhibit self-renewal and multi-lineage hematopoietic reconstitution.
• Engineered HSCs successfully engrafted in primary and secondary recipients, restoring adaptive immunity in immune-deficient mice.
• Single-cell analysis revealed a hybrid cell state in engrafted HSCs, co-expressing gene networks of stem/progenitors and differentiated lineages.

Conclusions:

• Modulating genetic programs, specifically HoxB4 expression and Notch signaling, enables the engineering of fully functional HSCs from pluripotent stem cells.
• These engineered HSCs demonstrate potential to address donor limitations and immune-mismatch issues in transplantation.
• The study reveals a novel hybrid cell state critical for HSC function within the bone marrow niche.