Photodymic Therapy for Intimal Hyperplasia : Targeted Drug Delivery by Scavenger Receptors

我们之前已经证明，与Texas-Red结合的马来化牛血清白蛋白（mal-BSA）荧光探针可以通过清扫剂受体介导的机制选择性地靶向动脉/IH的损伤部位。因此，我们将光敏剂（氯e6）偶联到马来酰化bsa上进行选择性定位。在体内研究中，我们分析了培养的内皮细胞、平滑肌细胞和巨噬细胞对Cle6-mal-BSA结合物的摄取情况。发现巨噬细胞比平滑肌细胞或内皮细胞浓缩更多的缀合物。用大鼠模型评估了三种形式的Cle6在腹腔（球囊损伤）和胸腔（对照组）动脉中的荧光团摄取：(1)游离Cle6，(2)结合Cle6的BSA和(3)结合Cle6的阴性BSA。术后2周注射荧光化合物。注射后4小时，取伤主动脉和对照主动脉，荧光显微镜检查。Mal-BSA/Cle6注射组在新生内膜内侧显示高荧光分布。游离Cle6和BSA-Cle6没有表现出如此高的荧光水平。激光照射采用调至661nm的氩泵浦染料激光器。我们采用了两种能量密度：20 J/cm2和40 J/cm2。PDT 48小时后，切除动脉进行组织学检查。mal-BSA/Cle6注射组（20J,67%）与Cle6注射组（20J,0-20%）相比，内膜增生细胞明显受损。我们得出结论，mal-BSA/Cle6定位于IH的高内侧，并有效地作为PDT的光敏剂。PDT作为一种治疗IH的方法，在这种动脉壁损伤模型中显示出有效的效果。

We have previously shown that the fluorescent probe maleylated-bovine serum albumin (mal-BSA) conjugated with Texas-Red can be selectively targeted to the injured sites of arteries/IH via a scavenger receptor mediated mechanism. Therefore we conjugate photosensitizer (Chlorin e6) to maleylated-BSA for selective localization. In vivo study, endothelial cells, smooth muscle cells and macrophages in culture were analyzed for their uptake of Cle6-mal-BSA conjugates. Macrophages were found to concentrate larger amount of the conjugates than either smooth muscle cells or endothelial cells. A rat model was used to evaluate fluorophore uptake in abdominal (balloon injured) and thoracic (control) arteries for three forms of Cle6 : (1)free Cle6, (2)BSA conjugated to Cle6 and(3)mal-BSA conjugated to Cle6. Fluorescent compounds were injected 2 weeks after surgery. Four hours following injection, injured and control aorta were retrieved and examined by fluorescence microscopy. Mal-BSA/Cle6 injected group showed high fluorescence distribution in the inner side of the neointima. Free Cle6 and BSA-Cle6 did not demonstrate such high fluorescence levels. Laser irradiations were perfomed with a argon pumped dye laser tuned to 661nm. We employed two energy density : 20 J/cm2 and 40 J/cm2. Forty-eight hours after PDT,the arteries were excised and examined histologically. Intimal hyperplastic cells were significantly damaged in the mal-BSA/Cle6 injected group (20J,67%) versus Cle6 group (20J,0-20%). We conclude that mal-BSA/Cle6 localizes higher inner side of IH and functions effectively as a photosensitizer for PDT.PDT as a treatment of IH using this delivery system shows effective in this model of arterial wall injury.