Statius van Eps R G, Adili F, Watkins M T, Anderson R R, LaMuraglia G M
Division of Vascular Surgery, Massachusetts General Hospital, Harvard Medical School, Boston.
Lab Invest. 1997 Feb;76(2):257-66.
Photodynamic therapy (PDT), the production of cytotoxic free-radical moieties by light activation of photosensitizer dyes, is a novel approach to inhibit experimental intimal hyperplasia. Local eradication of vascular cells with this method in vivo is followed by expedient reendothelialization, and PDT of extracellular matrix (ECM) in vitro stimulates endothelial cell (EC) growth. This in vitro study explored one possible mechanism underlying these findings by investigating the effects of PDT on matrix-associated transforming growth factor-beta (TGF-beta), a potent inhibitor of EC growth. The ECM deposited by EC on tissue culture plates contained 85.4 +/- 10.2 pg/10 cm2 of TGF-beta, as measured by an ELISA. In contrast, after PDT of ECM, levels of TGF-beta could be barely be detected (0.2 +/- 0.5 pg/10 cm2). The functional consequence of this observation was demonstrated by the finding that PD1 of plates coated with a fibronectin-TGF-beta complex stimulated EC mitogenesis (102.3% +/- 19.3%, p < 0.0005) compared with the untreated control (44.1% +/- 13.5%). The inhibitory effect of ECM-associated TGF-beta on EC was further delineated by blocking its activity with a specific antibody. Whereas the antibody did not affect EC mitogenesis or PDT-treated matrix or matrix-free plates (101% +/- 8.8%, 105.6% +/- 9.8%), EC mitogenesis growing on ECM was significantly enhanced (125.9%, 17.5%, p < 0.05). Finally, SDS-PAGE analysis of PDT-treated TGF-beta in solution demonstrated that the PDT-mediated loss of TGF-beta activity was not associated with changes in its molecular weight. These data demonstrate that increased EC proliferation on PDT-treated matrix is, at least in part, mediated by inactivation of TGF-beta. PDT-removal of this EC growth inhibitor in the intima provides a mechanism by which PDT of the vascular wall could potentiate endothelial regrowth, a factor which may promote proper healing and result in the inhibition of intimal hyperplasia.
光动力疗法（PDT），即通过光敏染料的光激活产生具有细胞毒性的自由基部分，是一种抑制实验性内膜增生的新方法。用这种方法在体内局部清除血管细胞后会迅速发生再内皮化，而体外对细胞外基质（ECM）进行光动力疗法可刺激内皮细胞（EC）生长。这项体外研究通过研究光动力疗法对基质相关转化生长因子-β（TGF-β，一种有效的内皮细胞生长抑制剂）的影响，探索了这些发现背后的一种可能机制。通过酶联免疫吸附测定法（ELISA）测量，内皮细胞在组织培养板上沉积的细胞外基质含有85.4±10.2 pg/10 cm2的转化生长因子-β。相比之下，对细胞外基质进行光动力疗法后，几乎检测不到转化生长因子-β的水平（0.2±0.5 pg/10 cm2）。这一观察结果的功能后果通过以下发现得以证明：与未处理的对照（44.1%±13.5%）相比，涂有纤连蛋白 - 转化生长因子-β复合物的平板进行光动力疗法后刺激内皮细胞有丝分裂（102.3%±19.3%，p<0.0005）。通过用特异性抗体阻断其活性，进一步阐明了细胞外基质相关转化生长因子-β对内皮细胞的抑制作用。虽然该抗体不影响内皮细胞有丝分裂或经光动力疗法处理的基质或无基质平板（101%±8.8%，105.6%±9.8%），但在内皮细胞外基质上生长的内皮细胞有丝分裂显著增强（125.9%，17.5%，p<0.05）。最后，对溶液中经光动力疗法处理的转化生长因子-β进行十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳（SDS - PAGE）分析表明，光动力疗法介导的转化生长因子-β活性丧失与其分子量变化无关。这些数据表明，在内皮细胞外基质经光动力疗法处理后内皮细胞增殖增加至少部分是由转化生长因子-β失活介导的。在内膜中光动力疗法去除这种内皮细胞生长抑制剂为血管壁光动力疗法增强内皮细胞再生提供了一种机制，这一因素可能促进适当的愈合并导致内膜增生的抑制。
