Emerging technologies in the biomolecular imaging..part-1

Basics of fluorescent proteins:
-Behaviour of highly metastatic cancer cells: label with green fluorescent protein (GFP)
-low metastatic cancer cells: labelling with red fluorescent protein (RFP)
-both can be done in-vivo

Or alternatively, the host and the tumour calls can be differentially labelled with fluorescent proteins –a transgenic mouse expressing GFP in all of its cells (or in specific cells such as endothelial cells) transplanted with tumour cells expressing RFP enables the interaction between the tumour cell and the hoist cells to be visualised in the real time.

Ex-vivo imaging, using the fluorescent proteins:
- examples include micro metastasis (including dormant cells ) which visualised in unfixed or unprocessed tissues
Intra vital imaging using the fluorescent proteins:
- the technique, High resolution Intravital video microscopy of GFP-expressing tumour cells gives directly observing steps in the metastatic process, individual, non-dividing cells, as well as micro- and macro metastasis, cellular details such as pseudopodial projections, tumour cell s motility (including moving in, and out of the blood vessels ). Along with the confocal microscopy, the polarity of tumour cells, response to the chemotatic cytokines etc can be visualised by the intra vital imaging technique.

Multiphoton laser-scanning microscopy (MPLSM): provides high resolution three –dimensional images of angiogenesis –associated gene expression and this technique also useful to investigate deeper regions of GFP-expressing tumours. Example include, monitored the” activity of VEGF promoter in transgenic mice and their subsequent blood vessel formation,


- Real time fluorescent imaging technique: also helping to discover new drugs and genes that mitigate cancer growth and progression.

-GFP-fluorescent tumour nodules can be detected by Fluorescence stereomicroscopy

-imaging the metastatic cells can be detected by confocal laser scanning microscope



-for tumour pathophysiology studies such as differentiating tumour vessels from both perivascular cells and matrix, assaying the ability of microparticles to access the tumour, and monitoring the trafficking of precursor cells: quantum dots and multiphoton intravital microscopy,


Colour-coding metastatic cells:
- in addition to the DNA micro array, this technique useful for visualisation of tumour cell types that have different properties in the live animal, visualising the action of specific genes in tumour growth and metastasis. Examples, include, Nucleoside diphosphate kinase A (NDPKA) a metastatic suppressor in certain tumours including breast cancer.

- This technique also useful for studies of different subpopulation of cancer cells to investigate the metastatic capacity of different cancer cells and also to understand how the expression of particular proteins drives or inhibits the metastatic process

Imaging dormant cells:

Dormancy means the tumour cells may lodge in some organs for instance lung but it won’t grow. This situation i.e. whether a cell that reaches a distant organ and proliferate or die or any factors that influence this process can b visualise by seeing the fluorescent proteins as well as fluorescent microscopy. Examples include studies of isogenic pair of metastatic and non-metastatic, GFP-labelled human breast cancer

(The studies of dormant tumour or stem-cells in in- vivo not only understanding of the dormant cells but also address why cancer patients can relapse many years after the eradication of the primary tumours, especially true for breast cancer patients. So there are no surprises that there are some biotech companies working on this field at USA!)

ps: Vey interestingly, the basics and the principles behind this fluorescent methods, proteins etc are also utilising in the field of cancer stem cells..

Reference: The multiple uses of fluorescent proteins to visualize cancer in vivo by Robert M. Hoffman, Nature Reviews Cancer 5, 796-806 2005