A New Dimension in Renal Clearance Design Criteria for Dendrimer Nanostructures

描述(由申请人提供)：我们研究的目标是为我们对树枝状大分子纳米结构肾脏清除设计标准的理解增加一个新的维度。我们通过了解树枝状大分子的表面电荷(SC)如何被用来调整其药理性质来实现这一点。关于大小如何影响树枝状大分子在体内的行为的报道已经存在，但还没有广泛的药理学研究在保持SC恒定的同时改变SC的大小和大小不变。我们的目标是：合成不同大小的树枝状大分子；合成不同流体动力学半径(Rh)和恒定大小的树枝状大分子；并测定它们的药代动力学、生物分布和清除途径。树枝状大分子有一个带有重复单元的核心。这些重复的单位是从核心的武器中成长起来的。臂的数量是核心多重性(CM)。重复单元在某一点固定在核心上，分支从该点开始生长。这些分支的数目是分支连接倍数(BM)，并且重复单元的数目定义世代(G)。表面基团数(NSQ)为：NSG=CM*(BM)G。我们使用标准的多肽化学方法，通过收敛的方法来制备树枝状大分子。树突是通过将不同的重复单元从表面(双官能团Gd(111)-螯合物)连接到连接点而制备的。通过使用不同的CM核和连接由不同BM的重复单元制备的树枝，我们制备了不同NSG但相同Rh和不同Rh但相同NSG的树枝状大分子。用光散射和扩散有序核磁共振方法测量了相对湿度。我们用核磁共振和直接采血的方法得到了血浆清除曲线[Tr]P(T)。由[Tr]P(T)计算药动学参数和曲线下面积(AUC)。我们将树枝状大分子的价值与临床批准的低分子Gd(111)-螯合造影剂的价值进行比较。肾清除率与肾小球滤过率的比较是通过取正常动物和接受阴离子肾小管分泌抑制剂丙磺舒治疗的动物的尿中发现的剂量，并将其除以AUC来进行的。药代动力学数据的分析是通过用多室模型和非室模型来拟合[Tr]P(T)曲线来进行的。我们使用最大似然估计和线性模型来估计加性误差的方差。我们还利用Akaike的信息准则、Schwartz准则、模型参数的估计误差和残差分析来选择最大拟合精度和最小参数个数的模型结构。这有助于理解用于诊断和治疗的树枝状大分子的肾清除设计标准。这项研究确实增加了我们对控制和优化基于树枝状大分子的纳米结构肾脏清除所需的设计标准的理解的新维度。所获得的知识是制造低毒、低全身滞留的树枝状大分子用于治疗和诊断的基础。

DESCRIPTION (provided by applicant): The goal of our research is to add a new dimension to our understanding of the design criteria for renal clearance of dendrimer based nanostructures. We achieve this by gaining an understanding of how surface charge (SC) on dendrimers can be used to tune their pharmacological properties. Reports exist on how size affects the behavior of dendrimers in vivo, yet no extensive pharmacological study that keeps SC constant while varying the size and size constant while varying the SC exists. We aim to: Synthesize dendrimers of varying SC but constant size; Synthesize dendrimers of varying hydrodynamic radii (rh) and constant SC; and Determine their pharmacokinetics, biodistribution, and clearance pathway. Dendrimers have a core with repeat units. These repeat units grow from arms on the core. The number of arms is the core multiplicity (CM). The repeat unit anchors to the core at a point, and branches grow from that point. The number of these branches is the branch juncture multiplicity (BM), and the number of repeat units defines a generation (G). The number of surface groups (NSQ) is: NSG = CM* (BM)G. We use standard peptide chemistry to prepare dendrimers by convergent methods. Dendrons are prepared by linking the different repeat units from the surface (bifunctional Gd(lll)-Chelates) down to the attachment point. By using cores differing in CM and attaching dendrons prepared from repeat units differing in BM we prepared dendrimers with differing NSG but the same rh and differing rh but the same NSG. The rh is measured using light scattering and diffusion ordered NMR methods. We obtain the plasma clearance curves, [Tr]P(t), with MRI and direct blood sampling methods. From [Tr]P(t) we calculate the pharmacokinetic parameters and area under the curve (AUC). We will compare dendrimer values with those of a low molecular weight clinically approved Gd(lll)-chelate contrast agent. Renal clearance is compared to glomerular filtration rate by taking the dose found in the urine after t ~ "functional infinity" from normal animals and those treated with the anion tubular secretion inhibitor probenecid and dividing it by the AUC. Pharmacokinetic data is analyzed by fitting the [Tr]P(t) profiles with multicompartmental and non-compartmental models using ADAPT II. We use the maximum likelihood estimation and linear models for the variance of the additive errors. We also use Akaike's Information Criteria, Schwartz Criteria, estimated error of the model parameters, and residual analysis to select the model structure maximizing the fit accuracy and minimizing the number of parameters. This provides an understanding of the renal clearance design criteria for dendrimers used in diagnosis and therapy. This research literally adds a new dimension to our understanding of the design criteria needed for controlling and optimizing dendrimer based nanostructure kidney clearance. The knowledge gained is fundamental in making dendrimers for therapy and diagnosis with low toxicity and low whole body retention.