Accurate detection and quantification of blood vessel growth using nonsurgical methods would greatly complement current. In a new publication Chase Kessinger and Doctor Jinming Gao from the University of Texas Southwestern Medical Center at Dallas and co-workers have incorporated nanotechnology, material science, and the clinical imaging modality MRI, to create a nanosized probe capable of noninvasively visualizing and quantifying the blood vessel growth in tumours in a preclinical model.

Gao stated "Imaging tumour angiogenesis is important in early detection, tumour stratification and post-therapy assessment of antiangiogenic drugs. Current clinical modality for angiogenesis imaging utilizes dynamic contrast enhancement MRI by small molecular contrast agents. The method is based on the measurement of permeability of the contrast probes in well-established solid tumours and is not very specific to detect the early on-set of vessel formation. The dual functional nanoprobes aim to image angiogenesis-specific tumour markers that are overly expressed in the tumour vasculature during the early phase of angiogenesis."

The research team relied on nanotechnology and established super paramagnetic micellar nanoprobes (50-70 nm in diameter) with greatly improved MRI sensitivity over conventional small molecular agents. The nanoprobe surface was functionalized with integrins that are a cyclic peptide that can specifically bind to overexpressed on the tumour endothelial cells. The nanoprobes also had a fluorescent moiety used for the validation of targeted delivery to the tumour endothelial cells. Studies in cancer cells validated the increased uptake of nanoprobes compared to non-targeted-nanoparticles. The team employed a 3D high resolution acquisition method to visualize the accumulation of the micelle nanoprobes in tumours.

Gao said "Conventional image analysis of angiogenesis relies on the evaluation of 'hot spot' densities in 2D images. The 3D high resolution method allowed for the connection of the isolated 'hot spots' in 2D slices into 3D network structures, which greatly improves the accuracy of vessel identification and quantification."

In preclinical tumour models, MR imaging of the targeted contrast probes yielded vascularised network structures in 3D tumour images. The enhanced visualization allowed for a more accurate quantification of tumour angiogenesis. The results showed significant increase of contrast specificity of angiogenic vessels by the targeted nanoprobes over non-targeted micelles. These targeted nanoprobes may provide a useful contrast probe design for the clinical diagnosis of tumour angiogenesis.


COMPAMED.de; Source: Society for Experimental Biology and Medicine