Biomedical Engineering Reference
In-Depth Information
brain loses most of its plasticity so any significant tissue death can be profoundly
devastating. The use of stem cells to rescue or replace damaged nervous tissue
could provide a much needed therapy for this relatively common event. As early as
2001, it was demonstrated that the infusion of CB stem cells into an animal model
of stroke could reverse many of the physical and behavioral deficits associated
with this disease [
31
]. Studies demonstrated that direct injection of the stem cells
into the brain was not required [
32
], and theorized stem cells initiated endogenous
repair via the release of growth and repair factors triggered by the anoxia [
33
,
34
].
Significantly, unlike current pharmacological interventions that require treatment
within the first few hours after stroke, CB stem cell therapies were effective up to
48 h after the event [
35
]. In fact, administration of CB stem cells immediately after
the ischemic event may not be optimal in that the inflammatory milieu may be
toxic to the administered stem cells. Neuroprotective effects [
35
-
40
] as well as
functional/behavioral improvements [
35
,
39
,
41
] from CB therapies have been
widely reported. These observations implied that CB therapy mediated both direct
restorative effects to the brain as well as trophic neuroprotection. For additional
information one is referred to the 2007 review on cell therapies for stroke pub-
lished in Stroke [
42
].
Cerebral palsy (CP) is a devastating brain disorder that affects many children
worldwide. CB stem cells have shown promise in the treatment of CP in early
human trials. Recently, considerable excitement has been generated by anecdotal
reports of improvement after CB stem cell infusions in children treated in a clinical
study at Duke University. Although not a randomized trial, this treatment has been
used to treat more than 50 children with cerebral palsy. Although results of the
study have not been published, preliminary observations have been encouraging,
and many additional patients are actively enrolled. A placebo-controlled, FDA-
registered clinical trial is also underway at the Georgia Health Sciences University
[
43
]. Similar results for children with cerebral palsy have been reported recently
by investigators treating children in Europe and Asia (personal communication,
Novussanguis Foundation, Paris, France, May 2008). It appears that the younger
the patient the more significant the benefits that have been observed. However, the
optimal therapeutic regime and the mechanism(s) behind any beneficial effects
have yet to be determined.
Additional neural applications for CB stem cells are being investigated at The
University of Texas at Houston in an FDA-registered clinical trial to treat children
with traumatic brain injury utilizing autologous cord blood stem cell infusions
[
44
]. This study is based on successful results obtained with a similar autologous
bone marrow stem cell study and numerous animal studies demonstrating the
efficacy of stem cell treatments in models of traumatic brain injury [
45
].
Finally, observations that CB stem cells can become different types of nervous
cells in vitro [
19
,
22
,
23
] have led to investigations as to its use in spinal cord
injury. Spinal cord-injured rats infused with CB stem cells have shown significant
improvements 5 days post-treatment compared to untreated animals. The CB stem
cells were observed at the site of injury but not at uninjured regions of the spinal
cord [
31
]. This finding is supported by another study demonstrating that CB stem
