Nanotube x-ray for cancer therapy: a compact microbeam radiation therapy system for brain tumor treatment

Impact of the Spectral Composition of Kilovoltage X-rays on High-Z Nanoparticle-Assisted Dose Enhancement

Nanoparticles (NPs) with a high atomic number (Z) are promising radiosensitizers for cancer therapy. However, the dependence of their efficacy on irradiation conditions is still unclear. In the present work, 11 different metal and metal oxide NPs (from Cu (Z_Cu = 29) to Bi₂O₃ (Z_Bi = 83)) were studied in terms of their ability to enhance the absorbed dose in combination with 237 X-ray spectra generated at a 30–300 kVp voltage using various filtration systems and anode materials. Among the studied high-Z NP materials, gold was the absolute leader by a dose enhancement factor (DEF; up to 2.51), while HfO₂ and Ta₂O₅ were the most versatile because of the largest high-DEF region in coordinates U (voltage) and E_eff (effective energy). Several impacts of the X-ray spectral composition have been noted, as follows: (1) there are radiation sources that correspond to extremely low DEFs for all of the studied NPs, (2) NPs with a lower Z in some cases can equal or overcome by the DEF value the high-Z NPs, and (3) the change in the X-ray spectrum caused by a beam passing through the matter can significantly affect the DEF. All of these findings indicate the important role of carefully planning radiation exposure in the presence of high-Z NPs.

External beam radiation therapy with kilovoltage x-rays

Kilovoltage (kV) x-rays are most commonly used for diagnostic imaging due to their sensitivity to tissue composition. In radiation therapy (RT), due to their fast attenuation, kV x-rays are typically only used for superficial irradiation of skin cancer and for intra-operative RT (IORT). Recently, however, a number of kV RT techniques have emerged. In this review article, we provide a brief overview of the use of kV x-rays for RT. Various kV x-ray source technologies suitable for RT, such as conventional x-ray tubes as well as novel x-ray sources, are first described. This x-ray source section is then followed by a section on their implementation in terms of clinical, veterinary and preclinical applications. Specifically, IORT, superficial RT and dose enhancement with iodine and gold nanoparticles, as well as microbeam RT and FLASH RT are discussed in this context. Then, a number of kV x-ray RT applications in modeling and proof-of-principle stages, such as breast external beam RT with rotational sources, kilovoltage arc therapy and the BriXS Compton pulsed x-ray sources, are reviewed. Finally, some clinical and economic considerations for the development of kV RT techniques are discussed.

Current Use of Carbon-Based Materials for Biomedical Applications—A Prospective and Review

Among a large number of current biomedical applications in the use of medical devices, carbon-based nanomaterials such as graphene (G), graphene oxides (GO), reduced graphene oxide (rGO), and carbon nanotube (CNT) are frontline materials that are suitable for developing medical devices. Carbon Based Nanomaterials (CBNs) are becoming promising materials due to the existence of both inorganic semiconducting properties and organic π-π stacking characteristics. Hence, it could effectively simultaneously interact with biomolecules and response to the light. By taking advantage of such aspects in a single entity, CBNs could be used for developing biomedical applications in the future. The recent studies in developing carbon-based nanomaterials and its applications in targeting drug delivery, cancer therapy, and biosensors. The development of conjugated and modified carbon-based nanomaterials contributes to positive outcomes in various therapies and achieved emerging challenges in preclinical biomedical applications. Subsequently, diverse biomedical applications of carbon nanotube were also deliberately discussed in the light of various therapeutic advantages.

A proof of principle experiment for microbeam radiation therapy at the Munich compact light source

Microbeam radiation therapy (MRT), a preclinical form of spatially fractionated radiotherapy, uses an array of microbeams of hard synchrotron X-ray radiation. Recently, compact synchrotron X-ray sources got more attention as they provide essential prerequisites for the translation of MRT into clinics while overcoming the limited access to synchrotron facilities. At the Munich compact light source (MuCLS), one of these novel compact X-ray facilities, a proof of principle experiment was conducted applying MRT to a xenograft tumor mouse model. First, subcutaneous tumors derived from the established squamous carcinoma cell line FaDu were irradiated at a conventional X-ray tube using broadbeam geometry to determine a suitable dose range for the tumor growth delay. For irradiations at the MuCLS, FaDu tumors were irradiated with broadbeam and microbeam irradiation at integral doses of either 3 Gy or 5 Gy and tumor growth delay was measured. Microbeams had a width of 50 µm and a center-to-center distance of 350 µm with peak doses of either 21 Gy or 35 Gy. A dose rate of up to 5 Gy/min was delivered to the tumor. Both doses and modalities delayed the tumor growth compared to a sham-irradiated tumor. The irradiated area and microbeam pattern were verified by staining of the DNA double-strand break marker γH2AX. This study demonstrates for the first time that MRT can be successfully performed in vivo at compact inverse Compton sources.

Carbon-Based Nanomaterials for Biomedical Applications: A Recent Study

The study of carbon-based nanomaterials (CBNs) for biomedical applications has attracted great attention due to their unique chemical and physical properties including thermal, mechanical, electrical, optical and structural diversity. With the help of these intrinsic properties, CBNs, including carbon nanotubes (CNT), graphene oxide (GO), and graphene quantum dots (GQDs), have been extensively investigated in biomedical applications. This review summarizes the most recent studies in developing of CBNs for various biomedical applications including bio-sensing, drug delivery and cancer therapy.

Biophysical interactions between pancreatic cancer cells and pristine carbon nanotube substrates: Potential application for pancreatic cancer tissue engineering

Novel synthetic biomaterials able to support direct tissue growth and retain cellular phenotypical properties are promising building blocks for the development of tissue engineering platforms for accurate and fast therapy screening for cancer. The aim of this study is to validate an aligned, pristine multi-walled carbon nanotube (CNT) platform for in vitro studies of pancreatic cancer as a systematic understanding of interactions between cells and these CNT substrates is lacking. Our results demonstrate that our CNT scaffolds-which are easily tuneable to form sheets/fibers-support growth, proliferation, and spatial organization of pancreatic cancer cells, indicating their great potential in cancer tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1637-1644, 2018.

Neurocognitive sparing of desktop microbeam irradiation

BACKGROUND

Normal tissue toxicity is the dose-limiting side effect of radiotherapy. Spatial fractionation irradiation techniques, like microbeam radiotherapy (MRT), have shown promising results in sparing the normal brain tissue. Most MRT studies have been conducted at synchrotron facilities. With the aim to make this promising treatment more available, we have built the first desktop image-guided MRT device based on carbon nanotube x-ray technology. In the current study, our purpose was to evaluate the effects of MRT on the rodent normal brain tissue using our device and compare it with the effect of the integrated equivalent homogenous dose.

METHODS

Twenty-four, 8-week-old male C57BL/6 J mice were randomly assigned to three groups: MRT, broad-beam (BB) and sham. The hippocampal region was irradiated with two parallel microbeams in the MRT group (beam width = 300 μm, center-to-center = 900 μm, 160 kVp). The BB group received the equivalent integral dose in the same area of their brain. Rotarod, marble burying and open-field activity tests were done pre- and every month post-irradiation up until 8 months to evaluate the cognitive changes and potential irradiation side effects on normal brain tissue. The open-field activity test was substituted by Barnes maze test at 8th month. A multilevel model, random coefficients approach was used to evaluate the longitudinal and temporal differences among treatment groups.

RESULTS

We found significant differences between BB group as compared to the microbeam-treated and sham mice in the number of buried marble and duration of the locomotion around the open-field arena than shams. Barnes maze revealed that BB mice had a lower capacity for spatial learning than MRT and shams. Mice in the BB group tend to gain weight at the slower pace than shams. No meaningful differences were found between MRT and sham up until 8-month follow-up using our measurements.

CONCLUSIONS

Applying MRT with our newly developed prototype compact CNT-based image-guided MRT system utilizing the current irradiation protocol can better preserve the integrity of normal brain tissue. Consequently, it enables applying higher irradiation dose that promises better tumor control. Further studies are required to evaluate the full extent effects of this novel modality.

TRPM8: a potential target for cancer treatment

Transient receptor potential (TRP) cation channel superfamily plays critical roles in variety of processes, including temperature perception, pain transduction, vasorelaxation, male fertility, and tumorigenesis. One of seven families within the TRP superfamily of ion channels, the melastatin, or TRPM family comprises a group of eight structurally and functionally diverse channels. Of all the members of TRPM subfamily, TRPM8 is the most notable one. A lot of literatures have demonstrated that transient receptor potential melastatin 8 (TRPM8) could perform a myriad of functions in vertebrates and invertebrates alike. In addition to its well-known function in cold sensation, TRPM8 has an emerging role in a variety of biological systems, including thermoregulation, cancer, bladder function, and asthma. Recent studies have shown that TRPM8 is necessary to the initiation and progression of tumors, and the aberrant expression of TRPM8 was found in varieties of tumors, such as prostate tumor, melanoma, breast adenocarcinoma, bladder cancer, and colorectal cancer, making it a novel molecular target potentially useful in the diagnosis and treatment of cancer. This review outlines our current understanding on the role of TRPM8 in occurrence and development of different kinds of tumor and also includes discussion about the regulation of TRPM8 during carcinogenesis as well as therapeutic potential of targeting TRPM8 in tumor, which may be utilized for a potential pharmacological use as a target for anti-cancer therapy.