Homing in on blood stem cells

The process of migration of cells to the organ of their origin is known as homing and is the route for transplanted blood stem cells — hematopoietic stem/progenitor cells (HSPCs) — to travel to and establish residence in the bone marrow. Cell adhesion, which depends on interactions between extracellular molecules and intercellular receptors, underpins HSPC homing. 

A new study by Karmen Abuzineh and colleagues, based at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, suggests that the first step in homing is more complex than previously thought. 

According to the study, published in Science Advances, in HSPCs, external mechanical forces cause transient nanoscale reorganisation of CD44 clusters, which are cell surface markers involved in cell-cell interactions, cell adhesion, and cell migration. 

This can lead to large structural reorganisation of the network of actin fibres, which is essentially the cell skeleton. These structural changes affect the first step in the HSPC homing process.  

The research team detected these complex nanoscopic interactions using a new method, known as microfluidics-based super resolution fluorescence imaging. This method allows the user to visualise dynamic nanoscale interactions between cells, particularly in the presence of external forces.

Senior study author, Satoshi Habuchi, pointed out that this method “is applicable to a wide spectrum of researches,” but stressed that “expertise and time may be required to optimise the protocol for [each] particular system.”

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