Life Sciences Division

In mammals, bone marrow is the main site of haematopoiesis. Haematopoiesis is the process that enables blood cells to be created and replenished from haematopoietic stem cells (HSCs). It also plays a role in bone marrow engraftment, as well as in leukaemia (the uncontrolled proliferation of bone marrow cells).

A sharper understanding of this process, i.e. how HSCs migrate, niche, amplify and differentiate in vivo is an important step towards platforming new therapeutic strategies capable of improving engraftment and for understanding bone marrow invasion during leukaemia.

Medical imaging techniques such as MRI or PET do not offer the requisite power of resolution to visualize individual cells, and current cell imaging techniques are not powerful enough to non-invasively track HSC engraftment or the development of leukaemia.

A team from the Laboratory of Stem Cell Repair and Transcription Research (CEA/iRCM) partnered by the joint Inserm – CEA/I2BM In vivo imaging of gene expression research unit has developed a relatively non-invasive technology making it possible to track the fats of HSCs inside the body. The technique involves temporarily introducing a confocal 10,000-optical-fibre endoscope into the femoral cavity of an anaesthetized mouse. This device makes it possible to visualize the kinetics of stem cell niching and expansion, and see how fluorescent grafted stem cells are compartmentalized.

The team were thus able to observe the early stages of HSC colonization in the wake of a wave of radiation-induced bone marrow destruction. Furthermore, by grafting-in fluorescent leukaemic cells, they were able to study the kinetics of leukaemia development in the mouse.