Biomedical Engineering Reference
In-Depth Information
Discovering the answers to these questions may make it possible to understand
how cell proliferation is regulated during normal embryonic development or during
the abnormal cell division that leads to cancer. Such information would enable
scientists to grow embryonic and adult stem cells more efficiently in the laboratory.
Regenerative Therapy in Myocardial Infarction: Mobilization,
Repair, and Revascularization
Background and significance
: Coronary heart disease is currently the principal
cause of death in the United States. In 1997, 1.1 million Americans were diagnosed
with acute myocardial infarction (AMI), and 800,000 patients underwent coronary
revascularization. In patients with MI, scar tissue develops in the area of infarction
resulting in a decrease in cardiac contractility. This damage is irreversible and can
result in heart failure since cardiac cells cannot repair themselves.
There are a variety of cellular and molecular approaches to strengthening the
damaged heart, focusing on strategies to replace dysfunctional, necrotic, or apop-
totic cardiac cells with new ones of mesodermal origin [
1
]. A wide range of cell
types such as myogenic cell lines, immortalized atrial cells, embryonic and adult
cardiomyocytes, embryonic stem cells, teratoma cells, genetically altered fibroblasts,
smooth muscle cells, bone marrow-derived cells, and adult skeletal myoblasts have
all been proposed as useful cells in cardiac repair and may have the capacity to
perform cardiac work [
2-
10
]. Ultimately, it must be proven that cellular therapy
aimed at cardiac repair not only improves pump function but also reduces mortality,
morbidity, or both. During stem cell infusion due to organ damage with the goal to
repair it, injury to a target organ is sensed by distant stem cells, which migrate to
the site of damage and undergo alternate stem cell differentiation [
11,
12
] . These
events promote structural and functional repair. This high degree of stem cell plas-
ticity led researchers to investigate if dead myocardium could be restored by trans-
planting bone marrow (BM) cells. It was demonstrated that multipotent adult bone
marrow hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs) can
repopulate infarcted rodent myocardium and differentiate into both cardiomyocytes
and new blood vessels [
11
]. One of the first clinical studies done on the heart by
Strauer et al. [
28
] reported that autologous intracoronary mononuclear bone mar-
row cell transplantation is safe and appears to improve cardiac function and myo-
cardial perfusion in patients after acute MI (
n
= 10) [
12
] . However, the authors
concluded that further experimental studies, controlled prospective clinical trials,
and variations of cell preparations are needed to determine the role of this new
procedure for the treatment of patients after acute MI [
12
] .
