In this proposal we show the preliminary development of a novel intravital methods to concurrently visualize both splenic colony formation and bone marrow reconstitution by fluorescently tagged donor HSC/HPC populations. Our tibia window model allows direct visualization of early marrow engraftment dynamics of fluorescently tagged HSC/HPC populations in individual living mice for up to three weeks. The intravital CFU- Spleen model currently allows 1-2 concurrent observations of the extramedullary splenic microenvironments and bone marrow longitudinally in individual transplant recipients. The primary goal of this SHINE-II proposal is to improve the intravital CFU-Spleen model to increase the number and resolution of the spleen observations to better match the tibia window model. The ability to observe both marrow and extramedullary donor HSC/HPC engraftment and niche utilization dynamics in living recipients over multiple days/weeks post transplant will significantly enhance our understanding of transplant biology.
We have created a novel method of surgically installed windows to watch hematopoietic stem cells (HSC) function in both the bone marrow and spleen in living mice. We will be directly testing how HSC decide to grow in the spleen instead of the normal bone marrow. Understanding this process will help make human bone marrow transplants safer and useful for treating a wider array of diseases.