Astrocyte-secreted chordin-like 1 regulates spine density after ischemic stroke

Ischemic stroke occurs when the brain is deprived of blood flow, preventing cells from receiving nutrients necessary to perform basic vital functions. In the peri-infarct area neurons undergo an acute loss of dendritic spines along with morphological alterations, which ultimately modify synaptic plasticity and determine neuronal survival. Astrocytes have been shown to play protective or detrimental roles in neuronal survival post-stroke, depending on the specific stage, yet we lack a clear understanding of the underlying mechanisms triggered at these different time points. Recently chordin-like 1 (Chrdl1) was identified as an astrocyte-secreted protein that promotes synaptic maturation and limits experience-dependent plasticity in the mouse visual cortex, leading us to ask if Chrdl1 regulates spine density and recovery from stroke. Using photothrombosis to model ischemic stroke, we studied Chrdl1 KO mice during the acute and subacute phases post-stroke (1 and 7 days after injury, respectively) to assess the potential of Chrdl1 to regulate spine density, glial reactivity and injury volume, characteristics that are involved in functional recovery after ischemia. We find that the absence of Chrdl1 prevents ischemia-induced spine loss in the peri-infarct area, a feature that indicates an important role of astrocytes in recovery from ischemic stroke.