Transplantation of NSCs to replace degenerated neurons or genetically modified NSCs producing neurotrophic factors have been used to protect striatal neurons against excitotoxic insults.[62] At present, little is known regarding whether implantation of NSCs prior to neuropathological Fluorouracil cost damage could alter the progressive degeneration of striatal neurons and motor

deficits that occur in HD. This question is important since the genetic study of HD gene mutation[63] and neuroimaging can provide details on factors involved in the progression of HD,[64, 65] suggesting early intervention using brain transplantation could be effective in “pre-clinical” HD patients carrying the mutant HD gene. We have investigated the effectiveness of proactive transplantation of human NSCs into rat striatum of an HD rat model prior to lesion EGFR cancer formation and.demonstrated significantly improved motor performance and increased resistance to striatal neuron damage compared with control sham injections.[66] The neuroprotection provided by the proactive transplantation of human NSCs in the rat model of HD appears to be contributed by brain-derived neurotrophic factor (BDNF) secreted by the transplanted human NSCs. Rodents and primates with lesions

of the striatum induced by excitotoxic kainic acid (KA), or quinolinic acid (QA) have been used to simulate HD in animals and to test efficacy of experimental therapeutics on neural transplantation.[67] Excitotoxic animal models induced by QA, which stimulates glutamate receptors, and resembles the histopathologic characteristics of HD patients, check details were utilized for cell therapy with mouse embryonic

stem cells, mouse neural stem cells, mouse bone marrow mesenchymal stem cells and primary human neural precursor cells, and resulted in varying degrees of clinical improvement.[68-73] We have recently injected human NSCs intravenously in QA-HD model rats and demonstrated functional recovery in HD animals.[72, 73] The systemic transplantation of NSCs via an intravascular route is probably the least invasive method of cell administration.[73] Neural cell transplantation into striatum requires an invasive surgical technique using a stereotaxic frame. Non-invasive transplantation via intravenous routes, if effective in humans, is much more attractive. Systemic administration of 3-nitropropionic acid (3-NP) in rodents leads to metabolic impairment and gradual neurodegeneration of the basal ganglia with behavioral deficits similar to those associated with HD,[74, 75] and murine and human NSCs have been transplanted in the brain of 3-NP-HD animal models.[66, 76] The compound 3-NP is a toxin which inhibits the mitochondrial enzyme succinate dehydrogenase (SDH) and tricarboxylic acid (TCA) cycle, thereby interfering with the synthesis of ATP.[77] We have investigated the effectiveness of transplantation of human NSCs into adult rat striatum prior to striatal damage induced by 3-NP toxin.