Saving legs through stem cell transplantation
R. PRASAD
An ongoing trial uses adult stem cells from bone marrow to grow
collateral blood vessels
The clinical trial, which started in December last year, would enrol
60 volunteers
Trials done in a few countries have shown encouraging results
Smoking does not affect the lungs alone. The nicotine present in the
blood has a destructive effect on blood vessel muscles. It causes the
muscles to constrict and damages the vessel's inner lining. The end
result is that the main arteries that supply blood get blocked.
While nicotine affects all the vessels (arteries), the worst affected
parts are those below the knee joint. "Elsewhere there are rich
collaterals [smaller vessels that branch off from the main arteries]
and [the organs] do not depend on one artery for blood and the
requirement of blood is far more in the legs," explained Prof. K.S.
Vijayaragavan, Head of the Department of Vascular Surgery, Sri
Ramachandra University near Chennai.
Blood requirement by the legs goes up 12 times depending on the kind
of exercise the person is engaged.
The disease turns the vessels into rigid tubes, thus making them
incapable of expanding. And with the vessel muscles constricted, the
flow of blood to the peripheral parts gets compromised. The human
system reads this as lack of RBCs and produces more of them.
With more RBCs, the blood becomes thicker and this compounds the
problem as thicker blood has to flow through narrower vessels.
Unlike in the case of blocks typical of atherosclerosis caused by
cholesterol, the blocks seen in legs and caused by nicotine (thrombo
angitis obliterance) start from the toe and move up towards the thigh.
Early warning
Since the only symptoms are pain and inability to walk long
distances, patients generally ignore the early warnings and turn up
when the disease is at an advanced state. The only solution is
amputation.
Though exact figures are not available, the prevalence of the disease
in India is high, according to Prof. Vijayaragavan.
While performing a bypass surgery or doing a angioplasty are
recommended when detected early, growing more co-laterals is the only
recourse to save the legs from amputation when the disease is at an
advanced stage.
A clinical trial is currently under way at Shri Ramachandra
University to grow such collaterals using adult stem cells collected
from the bone marrow of the same patient. The study, which started in
December last year, would enrol 60 volunteers.
The Chennai based Asia Cryo-Cell Private Ltd, a private cord blood
bank, is an equity partner at TRICell Stem Cell Centre, which is
based at the University, where the trial is being conducted.
Two groups
Of the 60 volunteers, the first group of 30 would get 40 injections
of stem cell concentrate very close to the blood vessels and the
second group of 30 volunteers would get 20 injections very close to
the blood vessels and another 20 injections into the main artery
above the block.
Criterion used
"At least one of the three arteries should allow blood to at least
trickle; else it is useless," said Prof. Vijayaragavan, Principal
Investigator of the trial explaining the criterion used for selecting
the volunteers for the second group.
The injections — bone marrow aspirate — contain not just stem cells
but also other supporting cells that complement them, such as
platelets and RBCs. The stem cells and the supporting cells are
separated and concentrated using a small instrument.
Such trials are already under way at a few centres in the U.S. "The
same protocol followed in the U.S. is followed here," he said. Many
trials done in a few countries have shown encouraging results.
Safe and effective
One of the first studies reported in the journal Lancet in 2002 found
autologous implantation of bone marrow cells to be safe and effective
for achieving therapeutic vessel formation. The results were based on
a randomised controlled pilot study.
The authors found a "…striking increase in number of visible
collaterals vessels in 27 of 45 patients." They also reported that "…
bone-marrow transplantation effectively increased blood flow in all
45 legs."
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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