Alginate-Chitosan-Alginate Microcapsules for Oral Administration

Recent advances in Genomics have successfully stream-lined diagnostics and therapeutic approaches such as gene therapy and enzyme replacement therapy for inborn errors of metabolism (IEM)s . Orally-administered microencapsulated- genetically-engineered cells and enzymes in Alginate-Polylysine-Alginate microcapsules (APA) have successfully decreased the systemic blood levels of the phenylalanine in PKU and urea removal in uremia. Regardless of the nature of the compound encapsulated (cell or enzyme), the permeability of the microcapsule membrane must permit the diffusion of smaller molecules including peptides and proteins and the exclusion of leucocytes and immunoglobulins (MW>150 000). Membrane permeability is regulated by the MW of the polycationic layer and adsorption parameters. Single molecular weight solutes have been used to study the molecular weight cut-off of the membrane. In our study, the permeability of 500 ìm microcapules prepared by atomization followed by polyelectrolyte adsorption of Polylysine (MW 20,000-3000) and low and medium molecular weight Chitosans have been compared . The two types of microcapsules were incubated in trypsin in order to simulate the duodenum acidic pH environment. Post-incubation leakage results indicate that the ACA microcapsules are more suitable for oral administration.