No abstract

In Alzheimer's disease (AD), amyloid deposits along the brain vasculature leading to a condition known as cerebral amyloid angiopathy (CAA), which impairs blood-brain barrier (BBB) function and accelerates cognitive degeneration. APOE4 is the strongest risk factor for CAA, yet the mechanisms underlying this genetic susceptibility are unknown. Here, we developed an iPSCbased 3D model that recapitulates anatomical and physiological properties of the human BBB in vitro. Similar to CAA, our in vitro BBB displayed significantly more amyloid accumulation in APOE4 compared to APOE3. Combinatorial experiments revealed that dysregulation of Calcineurin/NFAT-signaling and APOE in pericyte-like mural cells induces APOE4-associated CAA pathology. In the human brain, we identify APOE and NFAT are selectively dysregulated in pericytes of APOE4-carriers, and that inhibiting calcineurin/NFAT-signaling reduces APOE4associated CAA pathology in vitro and in vivo. Our study reveals the role of pericytes in APOE4mediated CAA and highlights calcineurin/NFAT-signaling as a therapeutic target in CAA and AD.The BBB is critical for proper neuronal function, protecting the brain from pathogens and tightly regulating the composition of brain fluids. Neuronal health is directly coupled to the *

Mechanical and physical stimuli including material stiffness and topography or applied mechanical strain have been demonstrated to modulate differentiation of glial progenitor and neural stem cells. Recent studies probing such mechanotransduction in oligodendrocytes have focused chiefly on the biomolecular components. However, the cell-level biophysical changes associated with such responses remain largely unknown. Here, we explored mechanotransduction in oligodendrocyte progenitor cells (OPCs) during the first 48 h of differentiation induction by quantifying the biophysical state in terms of nuclear dynamics, cytoskeleton organization, and cell migration. We compared these mechanophenotypic changes in OPCs exposed to both chemical cues (differentiation factors) and mechanical cues (static tensile strain of 10%) with those exposed to only those chemical cues. We observed that mechanical strain significantly hastened the dampening of nuclear fluctuations and decreased OPC migration, consistent with the progression of differentiation. Those biophysical changes were accompanied by increased production of the intracellular microtubule network. These observations provide insights into mechanisms by which mechanical strain of physiological magnitude could promote differentiation of progenitor cells to oligodendrocytes via inducing intracellular biophysical responses over hours to days post induction.