Agarose enhances the viability of intraperitoneally implanted microencapsulated L929 fibroblasts

To achieve immunoisolation, mouse L929 fibroblasts were encapsulated in sim ilar to 400 pm poly(hydroxyethyl methacrylate-co-methyl methacrylate) (HEMA -MMA) microcapsules and were subsequently implanted in the peritoneal cavit y of syngeneic C3H mice. As a baseline for the use of genetically engineere d cells in cell encapsulation therapy, the L929 cells were transfected to e xpress a secreted form of human alkaline phosphatase (SEAP). implantation o f empty microcapsules in a PBS suspension resulted in deformation, aggregat ion. and poor retrievability of the microcapsules. Incubation of microcapsu les with medium containing xenogeneic horse serum prior to implantation inc reased the thickness of the fibrous tissue surrounding the microcapsules. H owever, immobilization of the microcapsules in a 4% (w/v) SeaPlaque(R) agar ose Eel prior to implantation allowed complete recovery of the microcapsule s and prevented their aggregation and deformation. As a result, similar to 50% of the encapsulated cells remained viable 21 days postimplantation. Mor eover, once the viable cells were released from retrieved microcapsules and regrown as monolayers, they expressed SEAP at;I level similar to their enc apsulated but nonimplanted counterparts.