August 20, 2010
Scientific team at the Roskamp Institute found evidence to support that processes controlling the growth of cerebral blood vessels are altered in the brains of transgenic mouse models of Alzheimer's disease
Scientists at the Roskamp Institute in Sarasota, in collaboration with researchers from the H. Lee Moffitt Cancer Center in Tampa, have found laboratory evidence that the processes controlling the growth of cerebral blood vessels are altered in the brains of transgenic mouse models of Alzheimer's disease (AD). Scientists say the discovery will provide a better understanding of the role of cerebrovascular lesions in AD brains and may explain why vascular insults synergistically precipitate the cognitive presentation of AD. In addition, their research may provide new therapeutical approaches which are desperately needed to tackle this devastating disorder.
AD is the most common form of dementia among the aging population and is characterized by the intracerebral accumulation of a small protein called -amyloid, as well as, neurofibrillary tangles that form in the neurons of the affected patients. In addition to neuronal damages, AD brains also present evidence of capillary degeneration and a reduction in brain capillary density which probably contribute to the decreased cerebral blood flow reported in all patients suffering from the disease. The growth of blood vessels (or angiogenesis) is controlled by the balance between several growth factors that can stimulate their growth and other molecules that inhibit their formation. The amount of growth factors that normally stimulate angiogenesis is elevated in AD brains, which could suggest that the growth of cerebrovessels would be stimulated in AD. The growth of tumors is dictated by their vascularization, this is particularly true for brain tumors which are highly vascularized. Therefore, in order to determine whether angiogenesis was possibly altered in AD brains, the researchers implanted brain tumors in transgenic mouse models of AD (that have been genetically engineered to reproduce some of the AD brain pathology) as well as normal mice and measured the growth of the tumors in the animals. "Interestingly, we observed that the growth and vascularization of brain tumors was reduced in transgenic mouse models of AD compared to normal mice, suggesting that the AD brain does not constitute a favorable environment to support the growth of new blood vessels." said Dr. Daniel Paris of the Roskamp Institute, lead author of the study published in the Journal of Neuroscience (J. Neurosci. 2010;30(34):11251-8). "Our data suggest the growth of new brain capillaries that takes place following a stroke for example, and allows for a restoration of the cerebral blood flow in the damage area, will be inhibited in AD. This may explain why vascular insults such as stroke are known to accelerate the cognitive decline in AD patients. Overall, our work suggests that therapies stimulating brain vascularization may be beneficial in AD patients.", Dr. Paris added. Epidemiological studies have highlighted that the incidence of cancer is reduced in AD patients whereas the prevalence of AD is reduced in patients with an history of cancer suggesting a biological link between cancer and AD. "As the growth of blood vessels is required for the development of tumors, our work suggesting some impairment in the growth of blood vessels in AD may provide a biological mechanism explaining this intriguing relationship between cancer and AD.", Dr. Paris said.
The Roskamp Institute is a not-for-profit research Institute located in Sarasota, Fla., that is dedicated to understanding the causes of, and finding cures for, neuropsychiatric and neurodegenerative disorders with an emphasis on Alzheimer's disease. The Institute's Memory Clinic also offers comprehensive cognitive and medical assessment toward differential diagnosis of Alzheimer's disease and offers treatments and disease management options once the diagnostic evaluation is complete.
For more information, please contact the Institute at (941) 752-2949, Roskamp's Clinical Trials Division in Sarasota at (941) 256-8018 or visit www.RoskampInstitute.com.
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