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Characterization of an Isogenic Disease Model of
Alzheimer’s Disease from Human iPSC-derived Neurons Coby Carlson, Jun Wang, Natsuyo Aoyama, Rachel Llanas, Kile Mangan,
Michael McLachlan, Tom Burke, Susan DeLaura, and Eugenia Jones
AD-model Generation
Amyloid Beta (1-40)
-11 -10 -9 -8 -7 -6 -5 -41000
1500
2000
2500
3000
3500
4000
Log [DAPT] (M)
Alp
ha
Co
un
ts
Genotype Phenotype iPSC line #
Control (WT) Healthy; normal 01279.107
APP A673T (homo) Isogenic AD model
01279.A27
01279.A32 APP A673V (het)
“Hot Topics” Introduction
The development of therapies for neurodegenerative diseases such as Alzheimer’s
disease (AD) has been hindered by limited availability of relevant human cells for
research and drug discovery. Using induced pluripotent stem (iPS) cell technology,
we have created an unlimited source of human neurons that incorporate specific
genetic profiles associated with AD pathology. Researchers are using these cells to
understand the fundamental mechanisms underlying AD and to identify novel drug
treatments for this disease.
AD is a progressive neurodegenerative disease that results in gradual memory loss
and impairment in the ability to learn or carry out daily tasks. Recent studies estimate
that AD may contribute to as many deaths as heart disease and cancer combined.
Development of therapies for the treatment of AD is lengthy, costly and has been
largely unsuccessful, with drug attrition rates of >90%. As a result, there are no cures
and few treatment options.
A hallmark of AD pathology is the development of toxic plaques in the brain that contain
beta amyloid (Aβ), which is produced from amyloid precursor protein (APP). To
build a cellular model that could help to better understand the mechanisms by which Aβ
is produced, we used iPSC technology and genetic engineering to create human
neurons that exhibit AD-specific profiles. Our studies with these human iPSC-derived
neurons highlights the “disease-in-a-dish” approach for AD drug development.
iPS Cells
Genetic
Engineering
Human Neurons
Cortical Neuron Production Electrical Activity in APP Variants Correlates
with Allele: A673T > WT > A673V
5 sec
A673T is the first variant in APP associated
with protection against amyloid pathology
and AD. A673T was identified in a whole
genome sequencing project of approx.
1,800 people from Iceland.
(Jonsson Nature 2012)
The A673V variant is also near the APP
beta-secretase cleavage site and the
mutation contributes to AD pathology not
only by increasing Aβ production, but also
by enhancing aggregation and toxicity.
(Di Fede Science 2009)
(B) Real-time qPCR
analysis of a focus gene
panel reveals modest but
significant differences in
gene expression; notably
protein kinase C delta
(PRKCD) – involved in
learning and memory –
and the AD-associated
protein alpha-2-macro-
globulin (A2M)
WT control
βIII-
Tu
bu
lin
A673T A673V
Nestin
(A) Characterization of neuron
purity by flow cytometry. Using
the expression markers of βIII-
Tubulin (TUJ1) and Nestin, we
observed >98% pure neurons.
WT control (98.6%), A673T
(99.6%), and A673V (98.9%).
Day 7
Day 14
Day 21
WT control A673T A673V
MAP2 / Synaptophysin / DAPI
(C) ICC staining of neurons in culture
A 40/42 Ratio
-11 -10 -9 -8 -7 -6 -5 -41
2
3
4
5
Log [DAPT] (M)
A
40
/42
Ra
tio
(A) Measurement of AD-relevant
biomarkers by AlphaLISA: Aβ (1-40),
Tau, and sAPPα in iPSC-derived
neurons produced from a healthy
donor.
(B) Modulation of APP processing with
the -secretase inhibitor (DAPT)
shows a change in the amount of Aβ
(1-40) and the Aβ 40/42 ratio.
(C) Comparison of Aβ (1-40) levels in
neurons produced from a healthy
donor (WT, gray), an isogenic APP
A673T variant (blue), and an
isogenic APP A673V variant (red)
shows differences in the amounts
detected (HTRF assay). Treatment
with small-molecule inhibitors of
‒secretase (ie. BMS 299897 and
DAPT) resulted in decreased assay
signal (AlphaLISA) in all three APP
backgrounds.
AD Biomarker Levels Differ in APP Mutant and
Normal iPSC-derived Neurons
Amyloid Beta (1-40) Levels
To introduce these mutations in human iPSC-derived neurons, we genetically
engineered a “control” iPS cell line (01279.107) from an apparently healthy normal
Caucasian male donor (with no family history of neurological disorders) to engineer
either the A673T or A673V alleles.
;
• The A673T and A673V mutations were introduced in human iPSCs using TALENS.
• The APP A673T variant is homozygous, whereas the APP A673V variant is
heterozygous. Both are clonal.
• Cortical neurons were differentiated from these three unique isogenic iPSC lines
using CDI’s proprietary differentiation protocol outlined in the next panel.
These lines can be purchased from CDI.
β-secretase -secretase Aβ APP
Ala→Thr = protective and Ala→Val = causative A673
Day 6 Day 7 Day 15 Day 8
Bu
rsti
ng
Ra
te (
BP
M)
Fir
ing
Ra
te (
Hz)
WT A673T A673V WT A673T A673V WT A673T A673V WT A673T A673V
(A) Real-time heat map of
activity electrical activity
recorded on the 48-well
Maestro MEA system from
Axion BioSystems.
(B) Display of action potentials
captured from a 4x4 grid of
electrodes in a single well
(top) and the raster plot
depicting action potential
ticks across time for all 16
electrodes (bottom). Blue
tick marks indicate a
“Poisson surprise”-defined
burst.
(C) Mean firing rate (Hz; red)
and bursting rate (BPM;
blue) for WT, A673T, and
A673V neurons (n≥12) over
different DIV. Notice that
as the cultures mature,
bursting behaviors are
enhanced for A673T and
decreased for A673V.
Summary
Human iPS cells were genome-edited to create isogenic
cell lines for modeling Alzheimer disease (AD) .
Cortical neurons can be derived from human iPS cells
with different genetic backgrounds at high purity.
Wild-type APP, A673T, and A673V neurons express Tau,
APP, and amyloid beta isoforms. Treatment with drugs
modulated Aβ levels in the expected manner.
Protocols for handling iPS cell-derived neurons from CDI, as well as
performing various applications (ie. ICC, MEA) are available online.
Please contact CDI with any questions at: [email protected]
Future Directions
A
B
C
Schematic of cortical neuron differentiation process
Post-thaw
MyCell Neurons iPS Cell
Expansion
Neuron
Maturation
Day 0 Day 28-30
βIII-Tubulin-(+)
Nestin-(-)
Cell
Cryopreservation
Neuronal
Differentiation A B
C
Bursting electrical activity in neurons carrying the
Icelandic protective APP variant (A673T) is higher than
WT neurons, which are more active than AD-associated
A673V variant.
These data here are consistent
with previously reported AD
models of transfected HEK
293 cells and primary rodent
neurons (Jonsson Nature 2012
& Benilova J Biol Chem 2014).
The advantage of using Multi-Electrode Array (MEA) technology to assess neuronal
cultures is that it is a non-invasive, label-free method that enables the direct sensing
of voltage to characterize network-level phenotypes.
Recently published work from Genentech using these
neurons purchased from CDI shows similar differences
in APP processing (Maloney J Biol Chem 2014).
MyCell Neurons
(WT control)
Leveraging the power of iPSC technology, CDI is building out a
panel of MyCell Disease & Diversity Products, which includes
human neurons from donors of diverse ethnic and disease-
specific populations. Not only will there be more “controls”, but
also other innate disease models for ALS, Rett Syndrome,
Parkinson’s Disease, and epilepsy are being generated.
Abstract Control
Number: 1983
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B
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