Cellular labeling is a real medical need to forehead the growing interest in topics such stem cells and cellular therapy. New methodologies are needed that allow the in vivoobservation of administered cells, both in terms of their localization and functioning. The most suitable imaging technique for such applications is represented by Magnetic Resonance Imaging (MRI) both for its high spatial resolution and limited invasiveness. Besides the work on the improvement of the pinocytosis labelling procedure using polinuclear complexes of Gd (neutral and very hydrophilic), the work at CIM is oriented towards the following lines of research:
- Labeling through the mechanism of Receptor Mediated
The aim is to entrap sufficient amounts of contrast agents inside the endosomial vescicles within minutes since their administration, taking advantage of this mechanism of endocytosis. In order to increase the number of units of contrast agent internalized we make use of "nanocarriers" like liposomes or analogue structures. On their external surface, suitable functions will be inserted in order to target the receptor of interest. As an example, liposomes functionalized with ialuronic acid chains on their external surface are prepared and filled up with complexes of Gd. The ialuronic acid is a ligand for the CD44 membrane receptor. The ialuronic acid can be covalently or non-covalently conjugated to the surface of the liposome. In the latter case, cationic liposomes are used so that negatively charged ialuronic acid ligands can electrostatically cover the liposome surface.
- Labeling through the use of "Nanocarriers on a
Although the internalizzazione in the endosomi joins sufficiently very tolerated (also on the long times) thinks that this method can offer solutions of several interest in contexts applied to you. The method consists in loading "nanocarrier" with a contrast agent and therefore to put this "nanocarrier" to the towing of cells that have therefore the task to guide them towards "target" of interest. "Linker" between the surface of the cell and "nanocarrier" it can be represented from a simple polypeptide with opportune the distribution of regions to loads electrical worker defined so as to to guarantee the tie with the excess of it loads electrical worker on "nanocarrier" and on the cellular membrane. Naturally "linker" it could be also legacy covalentemente to present groups on the cellular membrane or on "nanocarrier". The job also will be finalized to find the way to rilasciare "nanocarrier" with its cargo to the situated one of "targeting". In particular "linker" it will be planned in way from being able to be cut from specific enzymes presents in the interest region .
- Development of "gene-reporter" for MRI
Effective MRI are not still available "gene-reporter" that can be particularly useful in order to follow the differentiation of staminali cells. In particular a responsivo system is being developed to the activity of the β-Galattosidasi, an enzyme that often comes used through one very experienced procedure of genic insertion (Lac-z). A complex of Gd-DOTA funzionalizzato with a residual one will be synthetized constituted from a conjugated Catecolo-Galattosio. The breach of the tie between these two entity will carry to the exposure of catecolici groups on the surface of the paramagnetic complex. And' famous that the catecolica function spontaneously polymerizes for giving macromolecules of melaninico type. Therefore us expects accumulates it of Gd in answer to the activity of the enzyme β-Galattosidasi. An other system that will come developed regards a complex of responsivo Gd to the Glutammato-Decarbossilasi that is an enzyme that comes expressed in the differentiation of the staminali neuron cells while it is absent in the differentiation to glia.