Neural stem cells with the ability to form new neurons in the brain
are normally present in the hippocampus (the part of the brain connected
to learning and memory) and in the subventricular zone of the brain.
Neural stem cells have been found in epileptic brain tissue - outside
the regions of the brain where they normally reside. In a group of
patients who underwent surgery for epilepsy, over half had stem cells
where healthy individuals do not have them, revealed a study from
‘In a group of patients who underwent surgery for epilepsy, about 60% had epileptic tissue that contained neural stem cells that could be converted into neurons, astrocytes and oligodendrocytes.’
"We have confirmed what earlier studies indicated, and gained new
knowledge about molecular characteristics of these neural stem cells,"
says Milos Pekny, professor at the Institute of Neuroscience and
However, in eight of 14 patients in the study, neural stem cells were
present outside these regions, namely in the epileptic brain tissue that
was surgically removed.
Over 50 operations of this kind are conducted in Sweden each year,
of which about 20 in Gothenburg, with most patients becoming
seizure-free or having significant reduction in seizure frequency. After
an extensive investigation aiming at the precise localization of the
epileptic focus, brain tissue that is damaged due to malformation,
injury or other cause, is surgically removed.
Surgeons, neurologists and neuroscientists worked side by side in
the current study, which followed ethical approval and informed consent
from each patient. For research purposes, the team was allowed to
examine a small part of the removed tissue used for histopathological
examination - in the operating room and in the research laboratory, just
several minutes after removal.
"About 60% of the patients had epileptic tissue that contained
neural stem cells that could be converted into neurons, astrocytes and
oligodendrocytes (the three types of brain cells that neural stem cells
can differentiate into) when they were later grown in the laboratory,"
says Milos Pekny.
"This may point to a greater plasticity in the epileptic tissue,
which to some extent can be compared to the brain tissue of a newborn,"
continues Milos Pekny.
Scientists have gained a better molecular understanding of the
region of the brain in individuals with epilepsy which - due to a
developmental abnormality, trauma, stroke, or a growing tumor - has
stopped responding to control signals, and this results in recurrent
"The knowledge gained in this study primarily helps to improve our
understanding of the brain responses in epilepsy," outlines Milos Pekny.
Scientists have long speculated that astrocytes, the cell type that
controls many neuronal functions, give rise to neural stem cells in
damaged brain tissue.
"Our study suggest that this is not the case, at least in epilepsy,
and it contributes the advancement of our understanding of what can
happen in the brain in people with epilepsy," says Milos Pekny.