Photodynamic Therapy Mediated by 5-Aminolevulinic Acid Suppresses Gliomas Growth by Decreasing the Microvessels

Although 5-aminolevulinic acid（5-ALA）-mediated photodynamic therapy（PDT） has been demonstrated to be a novel and effective therapeutic modality for some human malignancies, its effect and mechanism on glioma are still controversial. Previous studies have reported that 5-ALA-PDT induced necrosis of C6 rat glioma cells in vitro. The aim of this study was to further investigate the effect and mechanism of 5-ALA-PDT on C6 gliomas implanted in rats in vivo. Twenty-four rats bearing similar size of subcutaneously implanted C6 rat glioma were randomly divided into 3 groups： receiving 5-ALA-PDT（group A）, laser irradiation（group B）, and mock procedures but without any treatment（group C）, respectively. The growth, histology, microvessel density（MVD）, and apoptosis of the grafts in each group were determined after the treatments. As compared with groups B and C, the volume of tumor grafts was significantly reduced（P〈0.05）, MVD was significantly decreased（P〈0.001）, and the cellular necrosis was obviously increased in group A. There was no significant difference in apoptosis among the three groups. The in vivo studies confirmed that 5-ALA-PDT may be an effective treatment for gliomas by inhibiting the tumor growth. The mechanism underlying may involve increasing the cellular necrosis but not inducing the cellular apoptosis, which may result from the destruction of the tumor microvessels.

Nanomaterials for visualized tumor surgical navigation and postoperative recurrence inhibition

Preoperative localization of the tumor sites and intraoperative real-time monitoring are essential for precise surgery but are meanwhile challenging due to the lack of high-resolution,easy-to-operate,and fast visualization techniques.On the other hand,tumor recurrence and metastasis after surgery greatly reduce the survival rate of patients.Intervening tumor recurrence during surgery is a future direction of tumor treatment.Nanomaterials with external condition responsiveness(light,ultrasound,and magnetic field)can accurately assist intraoperative detection and surgical resection due to their functions such as tumor cell targeting,fluorescence imaging,and real time monitoring,providing a more accurate,shorter duration,and visualization method of surgical resection.Moreover,nanomaterials are versatile and can easily be tailored for application in different tumors.Locally filled or systemically circulating nanomaterials with slow drug release and residual tumor cell-targeting ability have promising applications in inhibiting tumor recurrence.Here,we review surgical navigation and postoperative recurrence interventional nanomaterials and their landscape in guiding tumor treatment.We summarize the classification and characteristics of these nanomaterials and discuss their application in the surgical navigation and recurrence inhibition of different tumors.We also provide an outlook on the challenges and future development of nanomaterials for visualized tumor surgical navigation and postoperative recurrence inhibition.