The most common application of nanotechnology to the field of medicine is the use of nanoparticles for cancer detection, monitoring and treatment. Many of the biological processes that cause cancer occur at the nanoscale. It is therefore possible to manipulate the tumor environment using nanotechnology for both diagnostic and therapeutic purposes.
Nanotechnology for Cancer Therapy Studies
Current research is focused on applying nanotechnology to cancer treatments. The benefits of employing nanoparticles for therapy include:
- Improved drug delivery by overcoming chemical and anatomical barriers within the tumor microenvironment. This is because nanoparticles can be designed with strategies for crossing these barriers for transportation of the drug to the tumor mass.
- Increased circulation times by reducing renal excretion.
- Providing site-specific drug delivery.
- Reducing the drug volume allowing for decreasing accumulation in healthy tissues.
- Providing a theranostic approach, where therapy and diagnostics are combined into one agent.
Nanotechnology and the Enhanced Permeability and Retention Effect (EPR)
The main mechanism by which nanotechnology provides important site specificity is through the enhanced permeability and retention effect (EPR). Solid tumors are characterized by leaky blood vessels. This is because the rapid growth of the tumor mass requires the quick expansion of the blood vessel network to fulfill the increased oxygen demand.
The poorly formed blood vessels consequently have pores that can leak molecules at the nanoscale into the tissue. Therefore, nanomedicine can passively accumulate in solid tumors without the need for active targeting. Because the tumor mass does not have a functioning lymphatic drainage system, this drug delivery mechanism also has the advantage of low levels of removal, furthering the amount of accumulation.
Studies are now attempting to improve the enhanced permeability and retention effect. Methods include the addition of vasoconstrictive drugs that work on normal blood vessels which increase the nanomedicine input in tumor tissues.
The ability to physiologically modify the tumor vasculature has been tested with the application of gold nanoparticles, which are conjugated to a peptide and produce photothermal damage to endothelial cells when light is applied. By damaging endothelial cells in the tumor vasculature, drug delivery may be improved by removing a physiological barrier.
Nanotechnology and Cancer Detection
Nanomedicine also has the potential to increase diagnostic sensitivity to the point where disease detection can be produced from small amounts of blood without the requirement for laboratory analysis. This technology has been applied to the development of simple blood tests that can detect and monitor brain cancer.
Microvesicles are fragments of plasma membrane that are shed by cells. Circulating tumor cells have the potential to be utilized for cancer diagnosis but unfortunately are not abundant within the blood stream. However, as microvesicles have the same biomarkers as their parent cells, microvesicle detection may be crucial to new methods of cancer diagnosis.
Due to their small size, technology in the nanoscale is required for their exposure. Nanotechnology is used to magnetically label microvesicles in order for their detection using portable nuclear magnetic resonance microscopy. The method achieves detection accuracy without the need for large blood samples.
Other potential cancer biomarkers include microRNA, which are non-coding portions of the RNA molecule that regulate gene expression. Variation in microRNA expression level has been found to correlate with the progression of cancer.
Their use in clinical diagnostics is currently limited due to the problems of quantifying such small molecules using traditional detection techniques. Nanotechnology is being utilized to form superior methods of microRNA quantification. Detection occurs by the pairing of microRNA with an added nucleic acid probe followed by the production of a measurable signal.
Nanoparticles increase signal output through the application of their enhanced optical and magnetic properties. The consequential ability to quantify microRNA with more accuracy will allow for standardized concentrations to be defined for cancer diagnosis.
Shelley Farrar Stoakes, MSc, BSc
- Rizzo, L.Y. et al. 2013. Recent Progress in Nanomedicine: Therapeutic, Diagnostic and Theranostic Applications, Current Opinions in Biotechnology, 24, e.1016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3833836/
- National Cancer Institute- Benefits of Nanotechnology for Cancer. https://www.cancer.gov/sites/ocnr/cancer-nanotechnology/benefits
- Kobayashi, H. 2014. Improving Conventional Enhanced Permeability and Retention (EPR) Effects; What Is the Appropriate Target? Theranostics, 4, pp. 81-89. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3881228/#Section4title
- Shao, H. et al. 2012. Protein typing of circulating microvesicles allows real-time monitoring of glioblastoma therapy, Nature Medicine, 18, pp. 1835-1840. http://www.nature.com/nm/journal/v18/n12/full/nm.2994.html
- Fiammengo, R. 2017. Can nanotechnology improve cancer diagnosis through miRNA detection? Biomarkers in Medicine, 11, pp. 69-86. https://www.futuremedicine.com/doi/full/10.2217/bmm-2016-0195