用于肿瘤治疗的光动力疗法

本文概述了光动力疗法的基本原理、光源和光波长的选择及光剂量的计算 ,介绍了基于ALA的PDT的原理及血红素的合成过程 ,并简述了PDT在肿瘤治疗方面的应用。

5-aminolaevulinic Acid-photodynamic Therapy for the Treatment of Cervical Condylomata Acuminata

Objective To investigate the efficacy and safety of photodynamic therapy （PDT） with topical 5-aminolaevulinic acid （ALA） on cervical condylomata acuminata. Methods Patients with cervical condylomata （n=30） were allocated into primary and recurrent group, and were given topical ALA under occlusive dressing for 3 hours followed by irradiation with semiconductor laser at a dose of 100 Jcm 2 and a power of 100 roW. The treatment was repeated 7 days later if the lesion was not completely removed after the first treatment. Complete response rate and recurrence rate of wart lesions as well as rate of adverse reaction were analyzed. Results The total complete response rate of PDT was 100% and the total recurrence rate was 5% after 3 months of follow-up. Recurrence rate of recurrent group was significantly lower than that of prior managements （100%, P〈0.01）. The side effects of PDT in patients mainly included mild burning and/or stinging restricted to the illuminated areas, and was significant lower than their own control （25% vs. 100%, P〈0.05）. Conclusion Compared with conventional therapies, topical application of ALA-PDT is a simple, effective, safe, well-tolerated, and low recurrence rate treatment for cervical condylomata acuminata.

Metal stenting to resolve post-photodynamic therapy stricture in early esophageal cancer

Photodynamic therapy (PDT) is an established endoscopic technique for ablating Barrett's esophagus with high-grade dysplasia or early-stage intraepithelial neoplasia. The most common clinically significant adverse effect of PDT is esophageal stricture formation. The strictures are usually superficial and might be dilated effectively with standard endoscopic accessories, such as endoscope balloon or Savary dilators. However, multiple dilations might be required to achieve stricture resolution in some cases. We report the case of stricture that recurred after dilation with a bougie, which was completely relieved by a self-expandable metal stent.

A covalent organic framework-based multifunctional therapeutic platform for enhanced photodynamic therapy via catalytic cascade reactions

Utilizing the unique tumor microenvironment(TME)to conduct chemical reactions for cancer treatment becomes a hot topic recently.Nevertheless,single chemical reaction in TME is often restricted by scanty reaction substrates and slow reaction rate.Meanwhile,the toxic substances produced by the reactions are usually not enough to kill cancer cells.Herein,using covalent organic frameworks(COFs)as the template,Au nanoparticles(Au NPs)were subsequently grown on the surface of the COF,then a thin layer of manganese dioxide(MnO2)was coated over the material,and finally hyaluronic acid(HA)was introduced to improve the biocompatibility.The resultant product,named COF-Au-MnO2,was involved in several processes to form cascade reactions in the TME.Specifically,under hypoxic conditions,COF-Au-MnO2 could react with intratumoral H2O2 to produce O2 to enhance the type II photodynamic therapy(PDT),and Au NPs could decompose glucose to promote starving-like therapy.Besides,starving-like therapy can also produce H2O2 to increase O2 production.Simultaneously,MnO2 can consume glutathione(GSH)to enhance the antitumor efficacy,and the released Mn2+could be used for T1-weighted magnetic resonance imaging(MRI).Both in vitro and in vivo experiments had proven excellent cancer cell killing effect and antitumor efficacy of COF-Au-MnO2via such a cycle-like process.

A strategy for enhanced tumor targeting of photodynamic therapy based on Escherichia coli-driven drug delivery system

Escherichia coli(E. coli) DH5α has been recognized as a non-pathogenic bacterial strain with tumor colonization ability. However, whether such a bacteria-driven drug-delivery system can improve the targeting of tumor therapy or not remains essentially untouched. Herein, a series of zinc phthalocyanine(ZnPc) photosensitizers with different numbers of charges were prepared and their electrostatic adhesion properties on E. coli were investigated via measuring their fluorescence intensities by flow cytometer. Among these ZnPc photosensitizers investigated, the ZnPc conjugate with four positive charges(named ZnPc-IR710) exhibited the highest loading capacity and the best fluorescence imaging performance of E. coli. With the help of E. coli, E. coli@ZnPcIR710 presented a significantly enhanced cytotoxicity on human breast cancer MCF-7 cells compared with ZnPc-IR710(survival rate of tumor cells was 39% vs. 57% at a concentration of 50 nmol L-1). Moreover, in vivo study showed that E. coli@ZnPc-IR710 remarkably inhibited the tumor growth and resulted in a complete tumor growth suppress in subcutaneous mouse 4T1 breast tumor model. These results demonstrated the great promise of bacterial-guided photodynamic therapy(PDT) in the treatment of solid tumors, and provide a unique strategy to enhance the antitumor efficacy of PDT by utilizing bacterial vectors in tumors.