Quantitative 3D High Speed Video Analysis of Capsule Formation during Encapsulation Processes

摘要

Cell-based therapies to overcome common hormone deficiency diseases like diabetes mellitus show great promise but suffer from short supply of human tissue or cell material. Encapsulated xenogeneic tissues are an effective tool to overcome this lack. In numerous studies biocompatible hydrogels, especially alginate, shaped up as an excellent matrix which prevents immune response. Standard procedure in alginate encapsulation techniques is still capsule formation by impinging alginate-cell mixture in cross-linking solution to form a stable hydrogel, whereas the cross-linking process itself is not fully understood yet. Previously, we reported a method to observe and analyze alginate capsule formation. This "deformation-method" focuses of capsule's outer shape and uncovers viscoelastic properties and polymerization kinetics. The recently introduced "trajectory method" is capable of analyzing dynamics of encapsulated material and is here enhanced by 3-dimensionality, what gives additional information about optimizing encapsulation processes. In order to analyze and evaluate the path of graft moving, the process is recorded with a high speed camera (1000 frames per second) and movements of a graft are determined relative to the capsule's center of gravity. We show three dimensional trajectories (moving distance, velocity and acceleration) of encapsulated material and that these depend on alginate concentration. With this information possible harming effects of impinging processes such as acceleration or shear forces can be identified and if necessary minimized in future setups. This method has the potential to become an on-line evaluation procedure for encapsulation techniques in order to characterize and improve production of therapeutically relevant transplants.