Written by Katrin Braasch, postdoctoral fellow in the Piret lab, Michael Smith Laboratories
Dr. Corinne Hoesli, a former PhD in the research lab of Dr. James Piret, devised an emulsion-based method to encapsulate mammalian cells in 0.5 -10% alginate beads using a simple stirred vessel. Their protocol is described in a recent publication in the Journal of Visualized Experiments (JoVE): “Mammalian cell encapsulation in alginate beads using a simple stirred vessel”. Dr. Corinne Hoesli is now an Assistant Professor at McGill. Find the protocol and video here.
Cell encapsulation has been widely studied to protect transplanted cells from immune rejection or to provide support for immobilized cell culture. Bead generators usually used for cell encapsulation are limited in the viscosities of alginate that can be used for bead production. As a result, the beads obtained by conventional methods are permeable to antibodies resulting in reduced immunoisolation of the transplanted cells.
The alternative method described in the recent publication is based on using a single emulsification step instead of the conventional drop-by-drop production. Using a simple stirred vessel allows production at different scales (mL to 103 L) while keeping equipment costs low. A single emulsification step also allows for the production of beads with high sphericity at varying alginate viscosities. Of significance is that these improvements keep bead generation times short and cell survival high (70 – 90 %). Moreover, beads with reduced permeability towards antibodies can be obtained. The high-concentration alginate beads could reduce graft rejection after islet transplantation.