5/6 None of this would have been possible without my incredible team whose talent, passion and dedication over the past 3 years have driven our discoveries forward! It’s been a privilege to turn our bold ideas into meaningful advances together @DorotheeBornho1 @Amulya_vh & Newsha

3/6 Building on the momentum of our work in Münster, we aim to further uncover how the heart and the vasculature take shape—probing how dynamic forces from the extracellular matrix and blood flow influence cardiovascular cell fate and tissue morphogenesis.

And to my lab for all the hard work and hard fun for the last 2 years!

Special congratulations and thank you to my amazing postdoc @DorotheeBornho1 who did fantastic work - we make a dream team!

Our study provides several lines of evidence for diversity in origins and residences of hematopoietic cells, and uncovers the zebrafish heart as a long-term resident tissue of hematopoietic cells. Functional investigation of these cardiac-residing cells is underway.

We found that the numbers of cardiac-residing HSPCs are not affected by reduced cardiac trabeculation or contraction, indicating that HSPC-endocardial attachment is at least partly independent of heartbeat-/blood flow-induced biomechanical forces.

The attachment of hematopoietic cells to the endocardium relies on the adhesion molecules Integrin a4 and Vcam1b, the latter of which is enriched in ventricle endocardial cells to which HSPCs are attached.

Photoconversion of dorsal aorta endothelial cells, which undergo endothelial-to-hematopoietic transition, also reveals their stable attachment to the endocardium, thus uncovering heterogeneity of tissue sources of cardiac-residing hematopoietic cells.

Combining photoconversion experiments, ex vivo heart explants and 3D light-sheet imaging of the beating heart over 7 hours, we uncovered endocardial contribution to hematopoietic cells that reside in the heart as well as in other hematopoietic niches.

Imaging of the beating heart shows that these HSPCs are stably anchored to the endocardium and not part of circulating blood cells. They expand in numbers over time and remain attached to the endocardium until at least 10 days post fertilization.