Ce6 結合化療藥物 cisplatin或 doxorubicin之 雙效微脂體最適化探討

Abstract

在癌症治療上目前有手術切除、化學治療、標靶治療，以及光動力治療等等，我們結合化學治療與光動力治療，將兩種化療藥物doxorubicin (Dox)或cisplatin (cDDP)結合光感物質Chlorin e6 (Ce6)，以微脂體 (Liposome)劑型同時包覆化療藥物以及光感物質，我們稱這種同時具有化療以及光動力療法的藥物為雙效微脂體，並依照包覆化療藥物的不同，命名為PL-Dox-Ce6以及PL-cDDP-Ce6，其中PL指的是修飾Polyethylene glycol (PEG)的微脂體。本篇研究目的在於建立最適化的雙效微脂體。研究論文的第一部分在於藉由調整雙效微脂體PL-cDDP-Ce6以及PL-Dox-Ce6脂質組成比例，以增進雙效微脂體在血清中的穩定性。為此，首先建立可以有效率分離及純化微脂體的方法。我們利用spin column來有效地自血清中分離微脂體，並降低血清蛋白在分析上面的干擾。在脂質組成調整部分，調整微脂體中膽固醇以及PEG的莫耳比例，發現在雙效微脂體PL-Dox-Ce6中提高膽固醇可以讓Dox與血清共混時穩定度上升，然而Ce6的穩定度卻會下降。而當降低PL-cDDP-Ce6的膽固醇含量，對微脂體的cisplatin滲漏影響不大，但是卻會讓Ce6的穩定度下降。在調整PEG的部分，發現提高微脂體PEG的含量可以同時降低PL-Dox-Ce6之Dox以及Ce6的滲漏情形。另外，同時提高PL-Dox-Ce6的膽固醇以及PEG含量，和原先配方比較可同時降低Ce6和Dox的滲漏。論文的第二部分，為將雙效微脂體 PL-cDDP-Ce6或PL-Dox-Ce6結合能專一辨認腫瘤血管新生接受器的胜肽IVO8和IVO24，並且探討其標靶特性。將胜肽修飾的雙效微脂體藥物，以C26以及H460這兩種小鼠腫瘤模式，測試藥物在各個組織、臟器的累積量。從實驗結果發現，修飾這兩種胜肽的雙效微脂體在腫瘤的藥物累積量並不能提升；然而，有胜肽修飾的微脂體反而更容易累積在肝臟以及脾臟。

The Liposomal drug delivery systems have been extensively studied in increasing the therapeutic index of chemotherapy. Photodynamic therapy (PDT), which is based on the administration of a photosensitizer followed by the irradiation of selective light, is a therapeutic modality for cancer treatment. Previously, we have developed a polyethylene glycol (PEG) modified liposome simultaneously encapsulated with a photosensitizer, Chlorin e6 (Ce6), in the lipid bilayer and a chemotherapeutic agent, doxorubicin (Dox) or cisplatin (cDDP), in the aqueous interior. Here we named as dual-effect liposome PL-Dox-Ce6 and PL-cDDP-Ce6. In the first part of this study, we tried to tune the molar ratio of lipid contents in liposomes, and then examine the serum stability of liposomes in the presesence of 80% FBS. A spin column method was developed to separate the liposome and serum proteins. The results showed that liposomes and serum proteins could be separated by spin column. By increasing the molar ratio of cholesterol in PL-Dox-Ce6, we found that the stability of Dox in liposome could be improved, but a dramatic loss of Ce6 was also found. However, when we increased the molar ratio of PEG in PL-Dox-Ce6, the serum stability of Ce6 and Dox could be improved. If we increased the molar ratio of cholesterol and PEG in liposomes, we found that the loss of Ce6 and Dox was lower than the formulation of DSPC: CHOL:DSPE-PEG= 100:50:2 (molar ratio). In the formulation of PL-cDDP-Ce6, the loss of cisplatin wasn’t significant when we lowered its cholesterol content. However, the loss of Ce6 in PL-cDDP-Ce6 was found in lowering the molar of cholesterol. In the second part of this study, we tried to insert targeting peptides IVO24 and IVO8 which have been shown to target to the tumor vessels, into our dual-effect liposomes. In C26 tumor model, the drug accumulation in tumor sites was not significantly different between PL-cDDP-Ce6 and IVO24-PL-cDDP-Ce6. In H460 tumor model, the drug accumulation in tumor sites was not significantly different between PL-Dox-Ce6 and IVO24-PL-Dox-Ce6 or IVO8- PL-Dox-Ce6.