研究表明胶质瘤干细胞（GSCs）是胶质瘤难治和复发的根源，只有彻底杀灭肿瘤组织微环境中的GSCs才能彻底根除胶质瘤。5-氨基乙酰丙酸（5-ALA）荧光引导胶质瘤手术可以有效提高胶质瘤的术中识别，提高手术切除率并延长患者生存时间，但该技术对GSCs特异性及敏感性却不得而知，详细的GSCs的5-ALA代谢机制不明。我们前期研究明确了亚铁螯合酶、ABCB6以及寡肽转运蛋白在胶质瘤细胞5-ALA代谢过程中的作用，实现了靶向关键酶提高5-ALA荧光成像质量和光动力学效应的目的。本研究拟探索GSCs 是否激发5-ALA荧光以及成像质量，检测GSCs 5-ALA代谢酶的表达，证实其表达和干细胞5-ALA荧光激发的关系及详细机制；靶向干扰关键酶表达之后，检测GSCs 5-ALA荧光强度以及GSCs生物学行为的改变，并在此基础上探索联合靶向增强GSCs 5-ALA荧光成像质量和光动力学效应的可行性。

Gliomas are the most common primary brain tumors with limited therapeutic options, high recurrence rate and mortality. Recurrence of glioma frequently occurs within the marginal area of the surgical cavity due to invading residual cells. 5-aminolevulinic acid (5-ALA) fluorescence-guided resection has been used as effective therapeutic modalities to improve discrimination of brain tumor margins and patient prognosis. However, the 5-ALA imaging quality of glioma usually show vague, which makes tumor identification difficult, and the applicability of 5-ALA-based photodynamic therapy (PDT) is hampered by insufficient therapeutic efficacy in glioma tissues. To overcome these issues, we assessed the expression of ferrochelatase (FECH), ATP-binding cassette, sub-family B, member 6 (ABCB6) and Peptide Transporter 2 (PEPT2) gene, which encodes a key enzyme that catalyzes the conversion of protoporphyrin IX (PpIX) to heme, in glioma surgical specimens and manipulated the enzymes in human glioma cell lines. These results suggest that targeting the enzymes of 5-ALA metabolism to enhance PpIX fluorescent quality is a potential approach for optimizing the subjective discrimination of vague fluorescence and improving the effect of 5-ALA-PDT. The initiation and progression of various types of tumors, including glioma, are driven by a population of cells with stem cell properties. Glioma stem cells (GSCs) are located in specialized perivascular niche within tumors. These niches represent the hallmarks of malignant gliomas and bear analogy to the microenvironments in which physiological stem cells in the brain are found. The key enzyme cues and mechanisms of 5-ALA in GSCs are poorly understood. The challenge now is to better understand the complex mechanisms of transport of 5-ALA in GSCs, which will allow the development of effective strategies to enhance 5-ALA-based metabolic imaging and photodynamic therapy efficacy. The FECH, ABCB6 and PEPT2 mRNA expression was determined using quantitative RT-PCR (QRT-PCR) in GSCs and wild type glioma cell. Cells expressing key enzymes in GSCs and wild type glioma cell were identified using immunohistochemistry. The key enzyme transfection with small interference RNA (siRNA）or plasmid were performed to increase intracellular PpIX accumulation in GSCs. The phototoxicity of ALA-photodynamic therapy (PDT) after transfection with FECH and/or ABCB6 and/or PEPT2 was evaluated by cell apoptosis analysis. Our study is manipulated to show the functional characterization of FECH, ABCB6 and PEPT2 in transport of 5-ALA in GSCs, and enhance 5-ALA-based fluorescent metabolic quality and ALA-PDT efficacy by targeting key enzymes in vitro and in vivo