Biomedical Engineering Reference
In-Depth Information
Results of a new study published online on August 10, 2009 in the Proceedings
of the National Academy of Sciences question the long-term effects of transplanted
cells in the brains of patients suffering from Huntington's disease. The study,
conducted by Dr. Francesca Cicchetti of Laval University in Québec, Canada,
Dr. Thomas B. Freeman of the University of South Florida (USF) Department of
Neurosurgery and Brain Repair, Tampa, FL, and colleagues, provides the first
demonstration that transplanted cells fail to offer a long-term replacement for degener-
ating neurons in patients with Huntington's disease.
Amyotrophic Lateral Sclerosis and Stem-Cell Therapy
Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a
progressive disease that manifests as a gradual evolution and spread of weakness
and wasting of the affected patient's muscles. It leads to dysfunction, disability,
and ultimately death or chronic ventilator dependency, which occur an average of
3 years after weakness is first detected [ 77 ]. The pathophysiology of ALS is com-
plex and poorly understood despite many years of study, and because of this, no
treatments have proved effective in slowing disease progression to any significant
degree. Some scientists have suggested that stem cells, with their ability to differ-
entiate into a variety of cell lines, could play an important role in restoring dam-
aged motor neurons and even generating new ones [ 77 ]. Are stem cells a dream
come true for those with ALS? Or are they something less? The answer to both
questions may be “yes.” With the lack of effective drug treatments for ALS, and
compelling preclinical data, stem-cell research has highlighted this disease as a
candidate for stem-cell treatment [ 78, 79 ]. Stem-cell transplantation is an attractive
strategy for neurological diseases and early successes in animal models of neuro-
degenerative disease generated optimism about restoring function or delaying
degeneration in human beings.
The restricted potential of adult stem cells has been challenged over the past
several years by reports on their ability to acquire new unexpected fates beyond
their embryonic lineage (transdifferentiation). Therefore, autologous or allogeneic
stem cells, undifferentiated or transdifferentiated and manipulated epigenetically or
genetically, could be a candidate source for local or systemic cell-therapies in ALS.
Albert Clement and colleagues showed that in SOD1G93A chimeric mice, motorneu-
ron degeneration requires damage from mutant SOD1 acting in non-neuronal cells.
Wild-type non-neuronal (glial) cells could delay degeneration and extend survival
of mutant-expressing motorneurons [ 70 ]. Letizia Mazzini and colleagues [ 77 ]
injected autologous bone marrow-derived stem cells into the spinal cord of seven
ALS patients. These investigators reported that the procedure had a reasonable mar-
gin of clinical safety. The question was: where next? In 2004, the same group of
authors published the new data [ 79 ]. After the results they got with animal models
of ALS that stem cells significantly slow the progression of the disease and prolong
survival, they have evaluated the feasibility and safety of a method of intraspinal
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