An abundant myeloid progenitor shapes neonatal hematopoiesis of naked mole-rats

The naked mole-rat became an attractive model for biomedical research due to its exceptional longevity and resistance to disease, yet the developmental properties of naked mole-rat stem and progenitor compartments are poorly understood. Here we report a high frequency bone marrow progenitor, which we termed TC90, exclusively present in neonatal animals. TC90s were marked by an immunophenotype resembling adult naked mole-rat common myeloid progenitors (CMP) with mature neutrophilic Thy1.1-antigen levels and showed a clear differentiation bias and transcriptome signature towards myelopoiesis. TC90s overexpressed both CXCL12 and its alternative receptor CXCR7, thereby abrogating their homing capacity and produced multiple secreted matrix components related to neonatal bone marrow niche formation. We hypothesize that the TC90 cell population protects newborns during the critical transition at birth and shortly beyond by boosting a supply of innate immune cells. In summary, our results identify a transient cell stage during postnatal hematopoiesis unique to naked mole-rats.