Strong evidence has shown that iron chelation therapy can benefit Alzheimer's disease (AD) patients by depleting excess metals from the body. Unfortunately, problems with toxicity, route of administration and restricted ability of the iron chelators to cross the BBB have impeded the further development of this approach. Our long-term goal is to develop novel iron chelation therapeutic agents using nanoparticle drug delivery technology for AD prevention and treatment. The specific hypothesis is that nanoparticles conjugated with iron chelators can serve as vehicles not only to send chelators into the brain but also bring the iron (and some other metals)-chelator complexes out of the brain, hence preventing excess metal associated brain damage. This hypothesis is based on 1) nanoparticles can mimic selected lipoprotein particles and enter the brain via lipoprotein receptor-mediated mechanisms. 2) Some lipoprotein particles can also leave the brain via the same receptor-mediated mechanisms. 3) Our preliminary studies show that iron chelators can conjugate with nanoparticles and the formed particles have the potential to enter the brain by mimicking lipoprotein. More important, the chelators conjugated to nanoparticles retain metal binding ability and the metal-chelator-nanoparticle complexes are capable of mimicking some lipoprotein particles that can leave the brain. To demonstrate our hypothesis, the specific aims are proposed. 1. Synthesize iron chelators and conjugate them to nanoparticles, then test the metal-binding ability of the formed systems. Copper chelators will also be used for conjugation and testing to obtain insights into the roles of different metals in AD. The methods for synthesis and conjugation have already been developed by us or according to literature. 2. Characterize the plasma protein absorption patterns (PPAP) on the formed systems and the systems complexed with metals. The PPAP will be determined by the 2-dimensional gel analysis, and indicate the capabilities of the systems to mimic lipoproteins. Kinetic studies of the particle delivery systems bi-directionally across Brain Blood Barrier (BBB) will be conducted using an in vitro coculture BBB model. 3. Examine the ability of the systems to enter and leave the brain using in vivo kinetic studies with a modified procedure. The contents of nanoparticles and metal irons in mouse brain will be assessed using chromatography, Graphite Furnace Atomic Absorption Spectrometry (GFAAS), respectively. These contents in other organs, bloodstream and excretions will also be examined. 4. Demonstrate whether the systems remove iron or other metals from the brain of Alzheimer transgenic mice and Parkinson's disease rats, and prevent the brain from oxidative damage. In addition to brain, other compartments like in aim 3 will be examined for the nanoparticle, metal and oxidative damage levels. These endpoints will be determined by bio-, histo- and immunochemical methods and instrumental analyses such as GFAAS. ? ? This study will not only provide the insights into the mechanisms of AD development associated with excess metal ions, but also provide potential therapeutics. Moreover, this approach may be applied to other neurodegenerative diseases mediated by excess metals, and to neuro-imaging. ? ? ?
