Biocompatible Coating of Encapsulated Cells Using Ionotropic Gelation

Abstract

The technique of immunoisolated transplantation has seen in the last twenty years improvements in biocompatibility, long term stability and methods for avoidance of fibrosis in alginate capsules. However, two major problems are not yet solved: living cellular material that is not centered in the capsule is not properly protected from the hosts’ immune system and the total transplant volume needs to be reduced. To solve these problems, we present a method for applying fully biocompatible alginate multilayers to a barium-alginate core without the use of polycations. We report on the factors that influence layer formation and stability and can therefore provide data for full adjustability of the additional layer. Although known for yeast and plant cells, this technique has not previously been demonstrated with mammalian cells or ultra-high viscous alginates. Viability of murine insulinoma cells was investigated by live-dead staining and live cell imaging, for murine Langerhans’ islets viability and insulin secretion have been measured. No hampering effects of the second alginate layer were found. This multi-layer technique therefore has great potential for clinical and in vitro use and is likely to be central in alginate matrix based immunoisolated cell therapy.

Stem Cell Based Drug Delivery for Protection of Auditory Neurons in a Guinea Pig Model of Cochlear Implantation

“…The alginate hydrogel used in this study was produced using isoosmolaric reagents (storage solution and cross-linked solution). In a previous study, Ehrhart et al (2013) demonstrated the stable volume (low swelling behavior) of such UHV-alginate hydrogels in isoosmolaric media over time. However, for reasons of patient safety, the swelling behavior in perilymph has to be investigated in detail in future studies.…”

Microencapsulation for Clinical Applications and Transplantation by Using Different Alginates

“…They suggested that Ca 2+ is more hygroscopic and less prominent swelling occurs when compared with Ba 2+ [32]. Protecting the conformational polymer blocks during preparation of the alginate gels for microencapsulation has been reported using different methods including conjugation of long alkyl chains [33] or dodecylamine [34], temperature (up to 60°C ± 1°C) [35,36], emulsification by cationic agent [37], and ionotropic gelation of alginate layers [38], etc. Slow gelation utilizes the alginate solution in a more uniform structure in a gradual manner [35].…”

Advancements in Assessments of Bio-Tissue Engineering and Viable Cell Delivery Matrices Using Bile Acid-Based Pharmacological Biotechnologies

“…FTIR has also been utilised in studies of microencapsulated islets to demonstrate chemical composition, including of the microcapsules without the cells [ 35 , 36 ]. Most often, in the field of islet encapsulation, attenuated total reflectance (ATR), forming ATR-FTIR is deployed as it provides an analytical penetration depth of 0.2–2 µm allowing for multi-compartmental analysis within the microcapsule structure to take place [ 37 , 38 , 39 ]. FTIR does also have its disadvantages, including that only thin samples, often only up to 20 μm, can be analysed using this technique.…”