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A new validation method for clinical grade micro-encapsulation: Quantitative high speed video analysis of alginate capsule

: Meiser, I.; Müller, S.C.; Ehrhart, F.; Shirley, S.G.; Zimmermann, H.


Microsystem Technologies 21 (2015), No.1, pp.75-84
ISSN: 0946-7076
Journal Article
Fraunhofer IBMT ()

Micro-encapsulation of cells or tissues is a promising treatment for hormone deficiency diseases (diabetes mellitus, hypoparathyroidism etc.). Alginate, a polymer from marine brown algae, is excellent for encapsulation. Its hydrated structure keeps out large antibodies and immune system cells while allowing diffusion of nutrients and therapeutic factors. Alginate droplets, containing cells, are crosslinked to form stable spherical hydrogel capsules. The position of grafts within the capsule, which decisively affects vulnerability to the host’s immune response, has previously not been investigated during the process of crosslinking. We describe for the first time quantitative, high speed video analysis of two perpendicular projections of capsule shape and load during crosslinking. This gives characteristic "deformation plots" of the capsule and fully resolved "trajectories plots" of capsule load movement. We identify four stages of capsule formation, giving insights into physico-chemical processes involved. Further, we show that mechanical stress on the load can be deduced by measurement of the capsule’s shape.