Pastore C J, Isner J M, Bacha P A, Kearney M, Pickering J G
Department of Medicine (Cardiology), St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, Mass 02135, USA.
Circ Res. 1995 Sep;77(3):519-29. doi: 10.1161/01.res.77.3.519.
Smooth muscle cell accumulation is a key feature of restenosis that may be inhibited by the delivery of receptor-targeted cytotoxins. DAB389EGF is a recombinant fusion protein in which the receptor-binding domain of diphtheria toxin has been replaced by human epidermal growth factor (EGF). We investigated the effectiveness of DAB389EGF to inhibit neointimal hyperplasia in the balloon-injured rat carotid artery. Incubation of rat carotid arteries with 125I-labeled EGF revealed extensive EGF binding sites in the neointima of balloon-injured arteries. Sixty rats subsequently received either saline or DAB389EGF (total dose, 0.15 mg) delivered immediately following balloon injury either systemically, via 14-day continuous osmotic pump infusion, or locally, via 30-minute intraluminal incubation. The effect of both treatment strategies was measured 2 weeks after injury by cross-sectional morphometric analysis of intimal area, the ratio of intimal/medial area (I/M), and the percent luminal narrowing (%LN). In addition, proliferative activity was assessed by immunostaining for the presence of the proliferating cell nuclear antigen (PCNA). Compared with controls, systemic delivery of fusion toxin significantly reduced intimal area, I/M, and %LN by 40%, 40%, and 29%, respectively. However, these rats exhibited 2% weight loss, indicating mild systemic toxicity. Local, intraluminal administration of DAB389EGF yielded a more pronounced reduction in intimal area, I/M, and %LN by 74%, 79%, and 72%, respectively. This inhibitory effect was preserved at 3 weeks postinjury, and PCNA immunostaining of locally treated arteries revealed a virtual absence of proliferative activity in the neointima and media at this timepoint. In contrast to systemically treated rats, rats receiving fusion toxin locally gained weight at a rate similar to controls, indicating avoidance of systemic toxicity. We conclude that DAB389EGF is a potent inhibitor of neointimal hyperplasia in vivo and that whereas an inhibitory effect may be achieved by systemic delivery, local delivery appears to be more potent, avoids systemic toxicity, and thus represents a feasible strategy to preempt restenosis.
平滑肌细胞积聚是再狭窄的一个关键特征，而靶向受体的细胞毒素递送可能会抑制这种积聚。DAB389EGF是一种重组融合蛋白，其中白喉毒素的受体结合结构域已被人表皮生长因子（EGF）取代。我们研究了DAB389EGF抑制球囊损伤大鼠颈动脉内膜增生的有效性。用125I标记的EGF孵育大鼠颈动脉后发现，球囊损伤动脉的内膜中有大量EGF结合位点。60只大鼠随后在球囊损伤后立即接受生理盐水或DAB389EGF（总剂量0.15mg），给药方式分为全身给药（通过14天连续渗透泵输注）或局部给药（通过30分钟腔内孵育）。损伤2周后，通过对内膜面积、内膜/中膜面积比（I/M）和管腔狭窄百分比（%LN）进行横断面形态计量分析来测量两种治疗策略的效果。此外，通过免疫染色检测增殖细胞核抗原（PCNA）的存在来评估增殖活性。与对照组相比，全身递送融合毒素可使内膜面积、I/M和%LN分别显著降低40%、40%和29%。然而，这些大鼠体重减轻了2%，表明有轻度全身毒性。局部腔内给予DAB389EGF可使内膜面积、I/M和%LN分别更显著地降低74%、79%和72%。这种抑制作用在损伤后3周仍保持，此时局部治疗动脉的PCNA免疫染色显示内膜和中膜几乎没有增殖活性。与全身治疗的大鼠不同，局部接受融合毒素的大鼠体重增加速度与对照组相似，表明避免了全身毒性。我们得出结论，DAB389EGF是体内内膜增生的有效抑制剂，虽然全身递送可实现抑制作用，但局部递送似乎更有效，可避免全身毒性，因此是预防再狭窄的一种可行策略。
