Biomedical imaging as well as cell tracking play a key role in understanding structural as well as functional biological systems. However useful, traditional methods like bioluminescence and fluorescence imaging present some challenges that can be overcome with the use of nanotechnology.
Liposomes and polymeric nanovesicles, are of great interest due to their capacity to deliver a specific drug to its target while monitoring and tracking the location of the nanosystem in real time, and in vivo. This holds great potential to study the distribution as well as the bioaccumulation of the drug which is an indicator of efficiency and possible toxicity.
Additionally, a great variety of nanoparticles have already been developed and even used in clinical trials up to phase 4 for in vivo imaging, including spions, silver nanoparticles and CdS/ZnS quantum dots.
While this technology has been used to enhance different imaging modalities, it stands out in the case of magnetic resonance imaging as excellent contrasting agents. Nanoparticle cell tracking has also been reported with Magnetic Particle Imaging (MPI), fluorescence imaging, nuclear and photoacoustic imaging.
Additionally, nanoparticles can be multi-functional, allowing for different imaging methods to be used simultaneously and enabling more information to be obtained. Further functionalization can also help distinguish subtypes of tissues as in the case of tumors.
- Great biocompatibility
- High spatial resolution
- Higher penetration depth
- Non- ionizing radiation
- Great contrast agents for MRI
- High Image contrast
- Long-term tracking
- Higher labeling efficiency
- Stem cell tracking: Mesenchymal stem cells (MSC) are multipotent stromal cells that have a great potential to regenerate damaged or aged tissue. However, it is key to ensure that MSC thrive in the new environment and to control migration, differentiation and functionality of the cells. This can be done with nanoparticle imaging, for example in cardiac regenerative therapy.
- Sensing molecular events: New nanoparticles with a switch mechanism have been developed to sense the environmental changes of a target site such as glucose concentration or the presence of some enzymes that can be later visualized through MRI.
- Diagnostic: The use of nanotechnology has rised especially in cancer research to detect and control tumor spread. In addition, other tumor associated tissues can be monitored as lymph nodes status and angiogenesis. In addition, nanoparticles/nanovesicles can help the visualization of inflamed tissue.
Theranostics: Liposomes and PLGA modified nanovesicles have been used for simultaneous imaging and therapy, which help evaluate the efficacy of drug delivery by visualizing biodistribution and quantifiying the accumulation at the target site. An example of this use could be to track immune cells that are used for immunotherapy to assess their ability to enter the tumor site.