Areas of Interest
Stem cells; neural development and degeneration.
Human embryonic stem cells (hESCs), which are derived from
the inner cell mass of a pre-implantation embryo, have the
capacity to become all cell types in the body, including
neurons. They thus provide an invaluable tool for studying early
human neural development and exploring the potential treatment
of neurological diseases.
The first line of our research is to specify neuronal
subtypes from human ESCs. By applying a set of morphogens in a
specific time window, we now have a model system for efficiently
generating spinal motor neurons from hESCs. Another type of
motor neuron, cortical motor neuron, is specified by a very
different mechanism than spinal motor neurons in animal models.
However, no cortical motor neurons have been successfully
specified from hESCs. Here experiments are underway to generate
telencephalic neuronal subtypes including cortical motor neurons
from hESCs using epigenetic approaches and genetic
modifications.
Another line of our research is to model neuronal
degeneration in spinal muscular atrophy (SMA) by using hESCs as
an experimental system. SMA is caused by the mutation of a
single gene (survival of motor neuron, SMN) and subsequent
reduced levels of SMN protein. To achieve this, we will first
establish stable hESC lines with a deficiency in SMN protein
levels through RNA interference and lentiviral delivery. Spinal
motor neurons will then be differentiated from these hESC lines
and assayed for a variety of functional changes. Successful
establishment of this human cell model will provide a unique
platform of high-throughput drug screening for this debilitating
and fatal genetic disorder.
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This image shows the hESC-derived spinal
motor neurons, which are positive for HB9 (a motor neuron
specific marker, red) and βIII-tubulin (a neuronal maker,
green). Blue indicates Hoechst-stained nuclei. [copyrighted
and used with permission of the University of Wisconsin
Board of Regents] |
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Lab Rotation Projects
Our laboratory is studying neural differentiation and
degeneration using human embryonic stem cells as an experimental
system. Rotation students in the lab will have the opportunity
to learn a variety of techniques, including but not limited to:
stem cell culture, motor neuron differentiation from hESCs,
genetic modification of stem cells, immunohistochemistry,
confocal microscopy and quantitative PCR. Possible rotation
projects include:
1. Generation of telencephalic glutamatergic and GABAergic
neurons from hESCs.
2. Modeling motor neuron degeneration of spinal muscular atrophy
using hESCs.
Selected Publications
LI XJ, Hu BY, Jones SA, Zhang YS, Du ZW, Zhang SC. Directed
differentiation of ventral spinal progenitors and motor neurons
from human embryonic stem cells by small molecules. Stem Cells.
In press.
Li XJ, Yang DL, Zhang SC. Motoneuron and dopamine neuron
differentiation. In: Loring J, Wesselschmidt R, Schwartz P. eds.
Human Stem Cell Manual: a Laboratory Guide. Spiral Bound, 2008.
Zhang SC, Li XJ, Johnson MA, Pankratz M. Human embryonic stem
cells for brain repair (review). Philosophical Transactions:
Biological Sciences. 2008, 363:87-99.
Pankratz MT, Li XJ, Lavaute TM, Lyons EA, Chen X, Zhang SC.
Directed Neural Differentiation of hESCs via an Obligated
Primitive Anterior Stage. Stem Cells. 2007, 25:1511-1520.
Li XJ, Zhang SC. In vitro differentiation of neural
precursors from human embryonic stem cells. Methods Mol. Biol.
2006, 331:169-77.
Du ZW, Li XJ, Nguyen GD, Zhang SC. Induced expression of
Olig2 is sufficient for oligodendrocyte specification but not
for motoneuron specification and astrocyte repression. Mol.
Cell. Neurosci. 2006, 33:371-380.
Li XJ, Du ZW, Zarnowska ED, Pankratz M, Hansen LO, Pearce RA,
Zhang SC. Specification of motoneurons from human embryonic stem
cells. Nature Biotechnol. 2005, 23: 215-221.
Revised March, 2008. |
