A comparative study between MC-1 Cells and magnetic microparticles used for enhanced target delivery of therapeutic agents in the microvasculature

The use of a clinical MRI system for propelling and controlling the displacement of a ferromagnetic core along a pre-planned path in the blood vessels has been validated experimentally by our group. The results of the experiment suggest that a MRI platform could not only be used as an imaging or diagnostic tool, but also as an interventional platform. One important medical intervention where such a new technology could play a significant role is in target chemotherapy where enhanced targeting efficacy leading to a significant reduction of the amount of toxicity in the systemic blood networks while improving therapeutic efficacy using lower dosages could be achieved. But to improve tumor targeting, the overall dimensions of these magnetic microcarriers must be reduced to approximately 2 mum in diameter to allow them to circulate in the microvasculature prior to reach the tumoral lesions. Because of the substantial reduction of magnetic material embedded in these microcarriers, technological constraints such as cooling and limits in gradient amplitudes will reduce targeting efficacy. Hence, to improve targeting in the microvasculature, MC-1 cells, each with an overall diameter of approximately 2 mum are being considered by our group as microcarriers for the target delivery of therapeutic agents. Each flagellated bacteria cell of type MC-1 would provide a thrust force exceeding 4 pN, a value which can be very effective when operating in low Reynolds hydrodynamic conditions such as when navigating in the microvasculature. By combining the propulsion force of each MC-1 cell that is provided by a pair of flagella instead of an induced force generated from an external source, with magnetotaxis-based swimming direction control of the cells by computer while tracking the cells using MRI, enhanced targeting based on closed-loop navigation control can be achieved. Here, through a comparative study between these two novel approaches, we show the advantages of the use of these M- - C-1 cells as microcarriers when operating in the smallest diameter capillaries of the microvasculature.