Induction of cytotoxicity by photoexcitation of TiO2 can prolong survival in glioma-bearing mice

Abstract

We have investigated the possibility that photoexcited titanium dioxide (TiO2) could inhibit the growth of malignant cells. We studied the anti-glioma effects of nano-TiO2 excited with ultraviolet A (UVA) irradiation both in vitro and in vivo. Transmission electron microscopy demonstrated that glioma cells take up TiO2 by phagocytosis, and vital staining revealed that TiO2 alone has no effect on glioma cell proliferation. However, if TiO2 was combined with UVA irradiation the proliferation rate was decreased significantly compared to controls (P<0.05). RT-PCR suggested that TiO2 induction of glioma cell apoptosis is associated with changes in the expression of genes encoding Bcl-2 family members. We then investigated the in vivo antitumor effects of combined TiO2 plus UVA treatment of established glioma tumors. TiO2 plus UVA led to pronounced areas of necrosis, elevated indices of apoptosis, delayed tumor growth, and increased survival compared with the TiO2-alone control group (P<0.001). Log-rank survival analysis showed that median survival duration was prolonged (P<0.001). These findings suggest that nano-TiO2 based photodynamic therapy has potential in the treatment of glioma.

Nanoparticles in biomedical applications

“…TiO 2 nanoparticles have many unique properties such as biocompatibility, chemical stability and optical properties [173]. It is because of these properties that there has been a recent increase in the use of TiO 2 nanoparticles in biomedical applications such as drug delivery [174][175][176][177][178][179], bioimaging [175], photoablation therapy [180][181][182][183][184][185] and biosensors [186,187], which will be discussed further in Section 4. Other metal oxide nanoparticles that are gaining interest in biomedical applications are cerium oxide (CeO 2 ) nanoparticles or nanoceria.…”

“…Further work is needed to optimise this photocatalytic cancer treatment as UVA irradiation can damage healthy cells [180]. The photoexcitation of TiO 2 nanoparticles was investigated to inhibit the growth of malignant glioma cells by Wang et al [181]. In vitro and in vivo studies were carried out using U87-MG brain cancer cell line and female BALB/c-nude mice which were injected with glioma cells and the TiO 2 suspension was injected under the skin.…”

“…These results suggest the potential use of TiO 2 nanoparticles and UVA irradiation as a treatment for brain cancer. However, more research is needed [181].…”

“…TiO 2 has many unique features such as good biocompatibility, low toxicity, chemical stability and photocatalytic properties which makes it an attractive material for use in the biomedical industry. Due to its unique properties, lots of research has been carried out on using TiO 2 nanoparticles in different biomedical applications such as drug delivery, PDT, cell imaging, biosensors and genetic engineering [173][174][175][176][177][178][179][180][181][182][183][184][185][186][187]. In this review, we will discuss the use of TiO 2 nanoparticles in targeted drug delivery and PDT.…”

Diagnostic and Therapeutic Uses of Nanomaterials in the Brain

“…Similar results were found by Wang et al, who observed that the proliferation rate of U87 glioma cell line was decreased when TiO 2 nanoparticles were combined with UVA irradiation. Results from their work suggested that TiO 2 induction of glioma cell apoptosis is associated with changes in the expression of genes encoding Bcl-2 family members [317].…”