Stem Cell Technology for Neurodegenerative Diseases
National Institutes of Health
Ann Neurol. 2011 September ; 70(3): 353–361. doi:10.1002/ana.22487.
J. Simon Lunn, PhD, Stacey A. Sakowski, PhD, Junguk Hur, PhD, and Eva L. Feldman, MD PhD
Over the past 20 years, stem cell technologies have become an increasingly attractive option to investigate and treat neurodegenerative diseases. In the current review, we discuss the process of extending basic stem cell research into translational therapies for patients suffering from neurodegenerative diseases. We begin with a discussion on the burden of these diseases on society, emphasizing the need for increased attention towards advancing stem cell therapies. We then explain the various types of stem cells utilized in neurodegenerative disease research, and outline important issues to consider in the transition of stem cell therapy from bench to bedside. Finally, we detail the current progress regarding the applications of stem cell therapies to specific neurodegenerative diseases, focusing on Parkinson’s disease, Huntington’s disease, Alzheimer’s disease, amyotrophic lateral sclerosis and spinal muscular atrophy. With a greater understanding of the capacity of stem cell technologies, there is growing public hope that stem cell therapies will continue to progress into realistic and efficacious treatments for neurodegenerative diseases.
Neurodegenerative diseases create a tremendous societal burden due to their devastating nature, cost, and lack of effective therapies. Cellular therapies offer great promise for the treatment of these diseases, and research progress to date supports the utilization of stem cells to offer cellular replacement and/or provide environmental enrichment to attenuate neurodegeneration. In diseases where specific subpopulations of cells or widespread neuronal loss are present, cellular replacement may reproduce or stabilize neuronal networks. In addition, environmental enrichment may provide neurotrophic support to remaining cells or prevent the production or accumulation of toxic factors that harm neurons. In many cases, cellular therapies provide beneficial effects through both mechanisms.
Many questions still remain unanswered and certain issues must be addressed as we continue the translation of cellular therapies from the bench to bedside (Table 1). The pathophysiology of each neurodegenerative disease discussed in this review is unique, and thus requires careful attention to these topics: Which type of cells offer the best approach to treat this disease? What do we expect the stem cells to do, and what outcomes are predicted? How do we anticipate patients early and later in the disease course will respond to treatments? As we begin to design clinical studies that take into account these questions and learn lessons from the trials currently underway, we are poised to maximize the potential of cellular therapies to provide much-needed treatments for neurodegenerative diseases.