Biocompatibility and in vivo evaluation of oligochitosans as cationic modifiers of alginate/Ca microcapsules

The present article investigates the substitution of poly-L-lysine by two different oligochitosans as membrane-coating capsule, and its effect on different functionality parameters of cell microencapsulation. To address this issue, initially the biocompatibility of the two types of oligochitosan solutions was evaluated using erythropoietin secreting C2C12 myoblast cell line as model. In a second step, we encapsulated the cells within alginate microcapsules coated with each oligochitosan and a complete morphological and mechanical evaluation was performed. Finally, the in vivo functionality of the enclosed cells in the alginate-oligochitosan microcapsules was studied in Balb/c mice. Results show that both oligochitosans were biocompatible, not detecting statistical differences between them. The alginate-oligochitosan microcapsules were totally spherical and uniform and resulted in high hematocrit levels after subcutaneous implantation in mice. In fact, significantly higher hematocrit levels were found in the animals transplanted with the encapsulated cells compared with the control group. Finally, the histological analysis showed a mild fibroblastic reaction around the capsule membrane. These results suggest that alginate-oligochitosan capsules may be an interesting alternative to conventional alginate- poly-L-lysine capsules.