MUSA - Alberta Pharmacy Students' Association

35. Wykoff RF. Delusions of parasitosis: a
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Stem cells in cardiac repair: A review of the changing
landscape of cardiovascular medicine
Nicholas A. Avdimiretz, BSc
Medical Student (2013), Faculty of Medicine and Dentistry University of Alberta, Edmonton, Canada
Correspondence to Nicholas Avdimiretz: Email: naa1@ualberta.ca
Abstract
Cardiac disease is the leading cause of death
for both men and women in developed
countries. In Canada, the incidence of
diabetes and hypertension has recently
increased by 90% in middle income groups,
resulting in substantially more cardiac
disease. How can medical professionals
keep up with these statistics? Imagine if
physicians could regenerate the wounded
heart post-myocardial infarction, or even
bioengineer an entirely new organ. This
is the future of cardiovascular medicine.
Regenerating myocardium is hardly an easy
undertaking; the heart contains about 20
million cardiomyocytes per gram of tissue,
meaning – in the left ventricle alone – there
are approximately 4 billion cardiomyocytes
at risk during a heart attack. Many cells are
required to replace damaged tissue, making
complete regeneration challenging. In light
of the rich therapeutic potential seen in
both adult and embryonic stem cells, it is no
surprise that biomedical research on these
cells has seen an intense amount of activity
in the past decade. From fetal-derived
cardiomyocytes and skeletal myoblasts, to
bone marrow stromal cells and peripheral
blood CD34 + cells, a myriad of cell lines
have been tested to date. The last decade
has seen an explosion of novel approaches
using these cells to restore cardiac function
post-infarction: from developing cell-based
pacemakers and cardiac grafts, to building
bioartifical hearts. This review will paint a
picture of the rapidly changing landscape
of cardiovascular medicine by elaborating
on these new technologies. Limitations
of these approaches will be discussed, as
well as future developments. In the field of
cell-based cardiac repair, the possibilities
seem endless.
Preamble
Cardiac disease is the leading cause
of death for both men and women in
developed countries. In fact, cardiovascular
disease – including coronary heart disease,
hypertension, stroke, and congestive heart
failure – has ranked as the number one
cause of death in the US every year since
1900, except during the 1918 influenza
epidemic. 1 In 2007, heart disease accounted
for 26% of all deaths in the US, resulting
in an age-adjusted death rate of 211 per
100,000 people. 2 Also shocking is the cost
of medication, health care services, and lost
productivity due to heart disease in the US:
a projected $508 billion in 2010. 3 This cost
is not expected to decrease any time soon.
In Canada, the incidence of risk factors for
cardiac disease has increased substantially
over the past decade: both diabetes and
hypertension have increased by 90% in
middle income groups (roughly 50% of
the population), 4 resulting in substantially
more cardiovascular disease. What if there
existed a therapeutic technique to treat that
which physicians have for so long deemed
incurable? What if one could regenerate the
wounded heart after a myocardial infarction
using stem cells? Imagine if one could
bioengineer a new heart. This could be the
future of cardiovascular medicine.
Over the last decade, the utilization of
stem cells to repair the damaged heart has
seen an explosion of advancements. Novel
therapeutic techniques will be addressed in
detail: the methods used and the resulting
applications of these innovations will be
described. Limitations of these techniques
and future developments will also be
reviewed.
37. Narayan V, Ashfaq M, Haddad PM.
Aripiprazole in the treatment of primary
delusional parasitosis. Br J Psychiatry.
2008;193:258.
Introduction to Cardiac Repair
Cell therapy has experienced much
growth over the last 25-30 years: from
its first applications for reconstituting
the immune system after a bone marrow
transplant, to treating diabetes with
pancreatic islet transplantation. 5 More recent
treatments include those for liver cirrhosis,
Huntington’s disease, and Parkinson’s
disease. 6 As for heart disease, the majority
of therapies have been centered on the
treatment of heart damage post-myocardial
infarction (MI). How can myocardial repair
occur in an organ that is thought to be
incapable of naturally self-repairing itself?
The heart does not experience regeneration
as the liver does; following MI, scar tissue
forms over the infarcted area. Therefore,
much of the research has been geared
towards using cell-based approaches to
regenerate myocardium directly from
donor stem cells. Regenerating heart
muscle following an MI is hardly an easy
undertaking; the myocardium contains
about 20 million cardiomyocytes per gram of
tissue, so there are approximately 4 billion
cardiomyocytes at risk in the left ventricle
alone during a heart attack. Assuming
that any repair therapy restores at least
1/2 to 2/3 of the damaged myocardium,
true regeneration would require 500 to 800
million cells. 7 In light of the therapeutic
potential seen in both adult and embryonic
stem cells (coined ES cells by Martin in
1981), 8 it is no surprise that biomedical
research on these cells has seen an intense
amount of activity in the past decade.
Stem Cell Sources
Stem cells not only have an unlimited
capacity to self-renew, but they are also
pluripotent; this means that stem cells
can be induced to differentiate into cells
University of Alberta Health Sciences Journal • April 2012 • Volume 7 • Issue 1 13
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