Student Poster Presentation #12 (Session 2)
Effect of Extracellular Matrix Enzymes on Aβ Induced Alzheimer’s
Models of Human Induced Pluripotent Stem Cells
Julie Bejoy, Yan Li
Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Florida State
University, Tallahassee, Florida, USA
Abstract
Extracellular matrix (ECM) components of the brain are found to play important roles both in the neural development
stage and in the neurodegeneration like Alzheimer’s disease (AD). The hallmark of AD includes the accumulation of
amyloid β peptides (Aβ 42) which form the plaques called senile plaques. The study of plaques and the surrounding
microenvironment of AD brain revealed co-localized expressions of different ECM molecules such as proteoglycans
(heparin sulfate proteoglycans (HSPGs) and chondroitin sulfate proteoglycans (CSPGs)), metalloproteinases (MMPs),
and hyaluronic acid (HA) etc. compared to the normal brain. Since the disease modeling using transgenic animal
models of AD does not reflect the microenvironment in humans, this creates a necessity of developing complementary
models from human cells including induced pluripotent stem (iPS) cells. In this study, we used two previously
established neuron differentiation paradigms for obtaining a forebrain dominant culture from iPS cells. The first
protocol (cortical) used dual Smad inhibition followed by sonic hedgehog (Shh) pathway inhibition and stimulation
with fibroblast growth factor-2 to generate glutamatergic neurons. The second protocol used inhibitors of WNT, Shh,
and SMAD signaling to generate telencephalic neural precursors followed by activation of Wnt plus brain-derived
growth factor to produce hippocampal dentate gyrus granule neurons (hippo). AD-associated neural pathology was
obtained by exogenous Aβ 42 oligomers treatment. The cultures were then treated with heparin (Aβ affinity with
HSPG), heparanase (digest HSPGs), chondroitinase (digest CSPGs), hyaluronic acid, and the MMP inhibitor (SB-
3CT). The results from the study indicated that inhibition of HSPG binding to Aβ using either heparanase or heparin
can attenuate the impact of Aβ related neural cell death. Whereas the inhibition of CSPG and MMP2/9 induced more
neural cell death. The image analysis revealed that both heparin and heparinase treatment reduced Aβ expression and
also supported the survival of developed neurons by showing increased expression of later stage neurons (MAP2+).
The results should enhance our understanding of the contribution of ECMs to the Aβ-induced neural cell death.
Figures: Lactate dehydrogenase (LDH) results for the cortical protocol (A) and hippo protocol (E). Quantitative
analysis of live/dead cell viability of the cortical protocol (B) and hippo protocol (F) and for MMP inhibitor (C). Flow
analysis of reduced Aβ expression after Heparin treatment. Immunocytochemistry images for both Aβ and MAP2
expression after heparin and heparinase treatment for the cortical protocol (G(i)) and hippo protocol (G(ii)).
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