In-vitro analysis of APA microcapsules for oral delivery of live bacterial cells.

Oral administration of microcapsules containing live bacterial cells has potential as an alternative therapy for several diseases. This article evaluates the suitability of the alginate-poly-L-lysine-alginate (APA) microcapsules for oral delivery of live bacterial cells, in-vitro, using a dynamic simulated human gastro-intestinal (GI) model. Results showed that the APA microcapsules were morphologically stable in the simulated stomach conditions, but did not retain their structural integrity after a 3-day exposure in simulated human GI media. The microbial populations of the tested bacterial cells and the activities of the tested enzymes in the simulated human GI suspension were not substantially altered by the presence of the APA microcapsules, suggesting that there were no significant adverse effects of oral administration of the APA microcapsules on the flora of the human gastrointestinal tract. When the APA microcapsules containing Lactobacillus plantarum 80 (LP80) were challenged in the simulated gastric medium (pH = 2.0), 80.0% of the encapsulated cells remained viable after a 5-min incubation; however, the viability decreased considerably (8.3%) after 15 min and dropped to 2.6% after 30 min and lower than 0.2% after 60 min, indicating the limitations of the currently obtainable APA membrane for oral delivery of live bacteria. Further in-vivo studies are required before conclusions can be made concerning the inadequacy of APA microcapsules for oral delivery of live bacterial cells.

Investigation of a new microcapsule membrane combining alginate, chitosan, polyethylene glycol and poly-L-lysine for cell transplantation applications.

Microencapsulation of living cells may serve as an alternative therapy for patients requiring organ transplants. One of the limiting factors in the progress of such therapy is attaining a biocompatible and mechanically stable polymer. The current study investigates the potential of a novel membrane combining alginate, chitosan, polyethylene glycol (PEG) and poly-L-lysine (PLL) with the objective of proposing a membrane suitable for cell entrapment that may overcome some of the shortcomings of the widely studied alginate-poly-L-lysine-alginate (APA) capsules. The novel microcapsule was formulated using a 1.5% alginate solution coated with 0.05% chitosan, 0.1% PEG and 0.05% poly-L-lysine with a final layer of 0.1% alginate. Microcapsules having a diameter of 450 +/- 30 microm were prepared. Upon citrate treatment, the membrane remained intact and retained its spherical structure. The membrane was able to support liver cell proliferation and the encapsulated cells were capable of secreting proteins. The study demonstrated that the new membrane can be used for cell entrapment. However, further investigations are needed to assess its potential for long term transplantation and usage in the development of bioartificial organs.