Biomedical Engineering Reference
In-Depth Information
One major obstacle in stem cell use is the problem of rejection. If a patient is
injected with stem cells taken from a donated embryo, his or her immune systemmay
see the cells as foreign invaders and launch an attack against them. Using adult stem
cells or induced pluripotent stem cells (IPSCs) could overcome this problem
somewhat because stem cells taken from the patient would not be rejected by his
or her immune system; however, the adult stem cells are less flexible than ESCs and
are harder to manipulate in the laboratory.
99
IPSC technology is too new for
transplantation work.
100
Finally, by studying how stem cells differentiate into specialized cells, the
information gained can be used to understand how birth defects occur and possibly
how to treat them. So, if there is so much potential in stem cell research, why all
the
controversy? Let
us
investigate
the
current
ethical
and
political
issues.
5,27,28,29,38,56,71,101-111
12.5.4 Results of Clinical Trials
In patients with acute myocardial infarction, progenitor cell transplantation aims to
prevent or ameliorate postinfarction LV remodeling, thereby reducing postinfarction
HF. Such an effect might be achieved by enhanced neovascularization and reduced
cardiomyocyte apoptosis, irrespective of long-term engraftment and transdifferen-
tiation. In patients with chronic HF, cardiomyogenesis in its pure sense would be
desirable.
58,85,91,96,112-115
12.5.5 Cell Therapy in Acute Myocardial Infarction
Infusion of autologous bone marrow mononuclear cells (BMCs) is safe and feasible
in patients with acute myocardial infarction, which is supported by the TOPCARE-
AMI, the BOOST trial, which showed there is improvement in global LV ejection
fraction by 7% to 9%, and there is significant reduction in LV end-systolic volume,
which has improved perfusion in the infarcted area in 4-6 months after cell
transplantation. Whereas the randomized, controlled trial by Janssen did not reveal
a significant effect on global ejection fraction, it did show an increase in regional
ejection fraction and a reduction of the infarct size in the BMC group. Another trial,
ASTAMI (Autologous Stem Cell Transplantation in Acute Myocardial Infarction),
did not show any benefit.
Overall, the clinical data available indicate that cell therapy with bone marrow-
derived cells is feasible and safe at least for the follow-up presently available (up to 5
years in the pioneering studies). None of the studies so far reported an increased
incidence of arrhythmias (as has been seen in myoblast trials). Moreover, restenosis,
which was considered as a potential side effect by progenitor cell-mediated plaque
angiogenesis or plaque inflammation, was increased only in one study using CD133
þ
cells, Because CD133
þ
cells were isolated by using a mouse antibody, one may
speculate that the remaining antibody might have elicited a local proinflammatory
reaction. All other studies did not observe an augmented risk for restenosis; if
anything,
there was a significantly decreased necessity for
revascularization
Search WWH ::
Custom Search