الفهرس 
Historical Review About Stem CellsOnly 14 pages are availabe for public view
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Abstract
The development of spinal cord injury treatment is focused on new
methods of regenerative medicine such as the administration of growth
factors, and An emerging strategy for replacing and/or regenerating
damaged tissue is the implantation of stem cells and/or artificial
biomaterials such as scaffolds to form tissue bridges between damaged
spinal cord stumps.
The use of autologous (Bone Marrow Cells) BMCs for stem cell
therapy in (Spinal Cord Injury) SCI patients has more advantages.
First, one can avoid all problems associated with the immunological
rejection or graft-versus-host reactions, which are frequently caused in
allogenic cell transplantation. Second, autologous BMC therapy is
considered safe by not being associated with carcinogenesis [Beachy etal
2004]. Third, extensive scientific data on BMCs have been accumulated
from previous experiences in BMC transplantation for hematological
diseases. These advantages have made cell therapy using BMCs widely
applicable and investigated clinically
in various neurologic diseases.
However, it also has some disadvantages. First, the procedure
requires open surgery to approach the injury area in direct method of
delivery, which results in the increase in the potential adverse effects.
Second, the sorting of BMCs needs to be done in vitro, thus increasing
the risk of contamination. Third, it is still unclear whether some BMC
components may have a deleterious effect on the functional improvement.
Also When bone marrow was aspirated from the iliac bone, and
mononuclear cells were sorted and concentrated.
Theoretically and clinically, lumbar puncture delivery of stem cells
is extremely attractive. Lumbar puncture is a minimally invasive
procedure that can be performed at the bedside after injection of a local
anesthetic. In humans lumbar puncture is performed at the L3–4 level, far
away from the cervical or thoracic spinal cord, which are the regions
most commonly effected by SCI. This makes lumbar puncture delivery of
stem cells relatively safe and unlikely to worsen compromised patients as
a direct result of the intervention .
Additional advantages of lumbar puncture delivery are related to
several factors:
4) The cells are delivered across the blood brain barrier into the
CSF, making it far more efficient than intravenous delivery.
5) CSF circulates within the CNS, allowing transplanted cells
to home into the injured tissues, and cells are preserved in a
relatively immune-privileged environment.
6) Because the transplanted cells are delivered away from the
hostile environment of the injured tissue, they are given a
greater opportunity to survive and migrate to the injury site
Intravenous Route: Least Efficient
Very few to no cells were present within the injured spinal
segments in rats that received BMSCs intravenously. In contrast,
considerably more cells were detected in the injured tissues after both
intrathecal and intraventricular delivery . These data confirm the
hypothesis that transplanting cells into the CSF leads to more successful
grafting when injection is via an intrathecal or -ventricular rather than
intravenous route. It should be noted that the same cell dosage (2 million
cells) was used for all routes and varying cell dosages might lead to
improved grafting efficacy.
The application of bone marrow derived leukocyte suspension,
including stem cells is a safe medical procedure with acceptable adverse
reactions. Improvement in the sensory function occurs in almost all of the
patients.
Improvement was recorded even in patients with lumbar infusion of
the stem cells, suggesting direct effect of stem cell implantation on
sensory improvement.
Very minor changes in motor function were noted in several of the
patients. Improvement initiated around the 90th day following
implantation of the stem cells and fully developed after the 8th month
from the procedure. Repetition of the stem cell implantation had a lesser
effect if any.
The most recent study done by Hadjianev in2008 show that
93.2% of the patients had improvement in the sensory function .
The improvement was noted in patients who had either laminectomy or
interlaminotomy
Few of the patients, mostly those with existing motor function
(14.8%), had improvement in movements. These improvements were
registered as an increase of the existing voluntary movements (abduction,
adduction, flexion and extension) or new activities in certain muscular
groups that were lost after the injury.
In some of the patients (9.5%), an absolute increase in the muscle
mass of the lower extremities (~1-1.5 cm in circumference) was
registered. Three of the patients who had partial sphincter control
following the accident regained full control after the procedure.(
Hadjianev A etal.,2008).
Conclusion
Of all types of implantation, Direct injection of stem cells gives the
best results
BMC implantation is promising, as regard, sensory function has
been improved, Also it shows some motor function improvement, as
regard the post traumatic existing voluntary movement, there is increase
in the muscle mass of the lower and regaining full sphincter control in
patients who had partial sphincter control.
A further more comprehensive multicenter study is recommended
to establish the therapeutic effect of stem cell implantation.