Dr. Joanna Rejman
Biotechnologist, Postdoctoral fellow
Laboratory of General Biochemistry & Physical Pharmacy
Imaging of survival and migration of stem cells
It is believed that stem cells can be grafted into the damaged tissue and thus may facilitate damage repair. Such stem cells could either be tissue specific stem cells (e.g. neuronal stem cells), expanded in vivo, or stem cells with multi- or pluri-potent differentiation ability (e.g. mesenchymal stem cells - MSCs, multipotent adult progenitor cells - MAPCs). Repair by both types of stem cells is probably mediated in part by cell replacement, but predominantly by trophic effects enhancing endogenous stem cell migration and differentiation. It has been demonstrated that MSCs migrate to significantly lesser extents than MAPCs when grafted in the brain of animals with stroke. This provides the opportunity to develop methods by which migrating and non-migrating stem cells can be quantified as well as methods that can increase or decrease migration inherent to the grafted cell population.
The aim of the project is to develop methods to modify endogenous and exogenous stem cells in order to be able to follow their migration and to demonstrate their persistence, as well as to manipulate their migration and survival ability in vivo.
To that end MSCs and MAPCs will be transfected with a cocktail of mRNAs using non-viral carriers (cationic lipids and polymers). This cocktail of mRNAs should allow transplanted stem cells to neo- or over-express chemokine receptors and neurotrophic factors in order (1) to improve their migration towards sites of neurotrauma, (2) to improve their survival at sites of neurotrauma, and (3) to improve the attraction and survival of recruited endogenous neural stem cells.
We will also design multifunctional non-toxic labeling agents to allow in vivo imaging of stem cells. Such particles should be able to be internalized by stem cells without modifying their biological activity. For the manufacturing of such particles the layer-by-layer (LbL) technique will be used. In all cases fluorescent markers will be incorporated in the particles in order to allow detection of their internalization by the stem cells. Iron oxide magnetic particles will be incorporated as a MRI negative contrast agent. Particles loaded with CT contrast agents will be produced by loading them with a high concentration of iodine. As an alternative to the use of a negative contrast agent we will attempt to apply manganese and gadolinium ions as positive MRI contrast agents. Therefore we will coat colloidal nano/microparticles with successive layers of polyanions and layers of the multivalent Mn2+ or Gd3+ ions.
The project is in collaboration with: