Chitosan as a matrix for mammalian cell encapsulation.

Cells encapsulated in a semi-permeable polymer membrane display enhanced viability and proliferation when sequestered along with a supportive matrix. In the present study, anionic sodium alginate and cationic chitosan were used as supportive matrices to study their influence on the growth of both anchorage dependent and independent cell types. A phaeochromocytoma-derived cell line, PC12, and two fibroblast cell lines, R208F and R208N.8, were encapsulated in sodium alginate microcapsules, crosslinked chitosan microcapsules and 60:40 acrylonitrile-vinylchloride copolymer (PAN/PVC) macrocapsules containing precipitated chitosan as an internal matrix. Microcapsules were maintained for 2 wk in vitro and macrocapsules were maintained for 4 wk. Both the PC12 and the R208F cells proliferated in the alginate microcapsules. Catecholamine release was detected from PC12 cell-loaded microcapsules. In contrast, the R208N.8 cells were not supported by the alginate and the only viable R208N.8 cells seen in this system protruded from the alginate matrix into the surrounding cationic poly-l-lysine lamina. All three cell lines grew poorly in crosslinked chitosan microcapsules yet they exhibited excellent viability when sequestered in PAN/PVC macrocapsules containing an internal matrix of precipitated chitosan. Significant catecholamine levels were detected from macroencapsulated PC12 cells while macroencapsulated R208N.8 cells released nerve growth factor (NGF) as demonstrated by a qualitative bioassay. This study shows that a cationic hydrogel, precipitated chitosan, supports attachment and spreading of fibroblasts when used as a matrix in the lumen of a PAN/PVC macrocapsule.(ABSTRACT TRUNCATED AT 250 WORDS)