NUP98-HOXA10hd fusion protein sustains multi-lineage haematopoiesis of lineage-committed progenitors in transplant setting.

Objectives: Exploring approaches of extending the haematopoiesis time window of MPPs and lineage-committed progenitors might produce promising therapeutic effects. NUP98-HOXA10hd (NA) fusion protein can expand long-term haematopoietic stem cells (HSCs) and promote engraftment competitiveness without causing obvious oncogenesis. Our objectives were to investigate the roles of NA fusion protein in MPP and downstream lineage-committed progenitor context.

Material And Methods: 300 sorted MPPs (Lin CD48 c-kit Sca1 CD135 CD150 ) were mixed with 5 × 10 total BM helper/competitor cells and injected into irradiated recipients. For secondary transplantation, 5 × 10 total BM cells from primary recipient mice were injected into lethally irradiated recipients. NA-MPP recipient mice were sacrified for flow cytometric analysis of bone marrow progenitors at indicated time points. Sorted MPPs and myeloid progenitors were used for RNA-seq library preparation.

Results: We showed that NA-expressing MPPs achieved significantly longer multi-lineage haematopoiesis (>44-week) than natural MPPs (20-week). NA upregulated essential genes regulating long-term haematopoiesis, cell cycle, epigenetic regulation and responses to stress in MPPs. These molecular traits are associated with the earlier appearance of a Sca1 c-kit myeloid progenitor population, and more abundant cellularity of lineage-committed progenitor as well as bone marrow nucleated cells. Further, the NA-derived primary bone marrow cells, which lack NA-LSK cells, successfully repopulated secondary multi-lineage haematopoiesis over 20 weeks.

Conclusions: This study unveiled that NA fusion protein promotes MPP and lineage-committed progenitor engraftment via extending long-term multi-lineage haematopoiesis.