Nanoparticle Brain Delivery of Iron Chelators for AD

描述（由申请人提供）：强有力的证据表明，铁螯合疗法可以通过从体内消耗多余的金属而使阿尔茨海默病（AD）患者受益。不幸的是，毒性、给药途径和铁螯合剂穿过血脑屏障的能力有限等问题阻碍了这种方法的进一步发展。我们的长期目标是利用纳米颗粒给药技术开发新型铁螯合治疗剂，用于阿尔茨海默病的预防和治疗。具体的假设是，与铁螯合剂结合的纳米颗粒不仅可以作为将螯合剂送入大脑的载体，还可以将铁（和其他一些金属）螯合剂复合物带出大脑，从而防止过量的金属相关的脑损伤。这一假设是基于1)纳米颗粒可以模拟选定的脂蛋白颗粒，并通过脂蛋白受体介导的机制进入大脑。2)一些脂蛋白颗粒也可以通过相同的受体介导机制离开大脑。3)我们的初步研究表明，铁螯合剂可以与纳米颗粒结合，形成的颗粒具有模仿脂蛋白进入大脑的潜力。更重要的是，与纳米颗粒结合的螯合剂保留了金属结合能力，金属-螯合剂-纳米颗粒复合物能够模拟一些可以离开大脑的脂蛋白颗粒。为了证明我们的假设，提出了具体的目标。1. 合成铁螯合剂并将其与纳米颗粒结合，然后测试所形成体系的金属结合能力。铜螯合剂也将用于偶联和测试，以深入了解不同金属在AD中的作用。我们或根据文献已经开发出了合成和共轭的方法。2. 表征形成的系统和与金属络合的系统的血浆蛋白吸收模式（PPAP）。PPAP将由二维凝胶分析确定，并表明系统模拟脂蛋白的能力。将使用体外共培养脑血屏障模型进行颗粒传递系统双向穿越脑血屏障（BBB）的动力学研究。3. 检查系统的能力，进入和离开大脑使用体内动力学研究与修改程序。采用色谱法和石墨炉原子吸收光谱法分别测定小鼠脑内纳米颗粒和金属铁的含量。其他器官、血液和排泄物中的这些成分也将被检查。4. 证明该系统是否从阿尔茨海默病转基因小鼠和帕金森病大鼠的大脑中去除铁或其他金属，并防止大脑氧化损伤。除了大脑，其他部分，如aim 3，将被检查纳米颗粒，金属和氧化损伤水平。这些终点将通过生物、组织和免疫化学方法以及GFAAS等仪器分析来确定。

DESCRIPTION (provided by applicant): 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.