Connective tissue progenitors (CTPs) are used as a therapy for bone repair. These cells can be isolated thanks to their expression of hyaluronan, a membrane glycosaminoglycan. Since these cells are rare relatively to other cells in the bone marrow (1 for 20000) it is difficult to obtain enough cells for therapeutical application. The problem with the application in humans is that CTPs need to be isolated from bone marrow suspensions to obtain a high number of viable cells. This procedure implies collecting bone marrow, separating the CTPs and engrafting them in the patient which, due to the complicated nature of rare cell isolations, would need two surgical procedures. Therefore the process of separation needs to be quick and efficient without impairing cell function.
In order to overcome these issues researchers from Cleveland have developed a device that allows to scale-up the purification of CTPs, maintaining a high purity and high viability of cells.This device is based on biomagnetic separation by a circular Halbacharray of diametrically magnetized, cylindrical permanent magnets. This device is simple to operate and has a processing capacity of 1 billion nucleated cells.
The developed protocol starts by labelling CTPs using anti-hyaluronan conjugated with magnetic beads that allow positive selection of these cells from bone marrow or buffy coats. Then the cell suspension is passed through the magnetic device and decanted to obtain a cell fraction enriched in CTPs. The in vitro cultures of obtained cells revealed that theywere more biologically active than the buffy coat samples, indicating that they have enough quality for clinical application. Since the whole separation procedure takes approximately 2.5 hours and is effective in obtaining a cost-effective enrichment of bioactive CTPs it has the potential to be applied during a single surgical procedure.
For the math:
Circular Halbach Array for Fast Magnetic Separation of Hyaluronan-Expressing Tissue Progenitors. Joshi, P., Williams, P. S., Moore, L. R., Caralla, T., Boehm, C., Muschler, G., &Zborowski, M. (2015).Analytical Chemistry, 87(19), 9908–9915. doi:10.1021/acs.analchem.5b02431
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