Objective   To investigate the mechanical strength

permeability and  biocompatibility of the microcapsules made of alginate-chitosan-alginate (ACA) or alginate-polylysine-alginate (APA)

and evaluate the feasibility of ACA and APA microcapsules as carriers of cell transplantation.    Methods   The ACA microcapsules and the APA microcapsules were prepared separately based on the microencapsulated 293 cells and alginate solution. The mechanical strength of the microcapsules was measured in the shaking apparatus at 37 ℃. The permeability of both microcapsules was observed in present of some proteins

such as trypsin

immunoglobulin IgG and bovine serum albumin by fluorescent microscopy. The ACA and APA microcapsules entrapping 293 cells were transplanted to the periorbit of New Zealand White rabbit and the abdominal cavity of SD rats. After microcapsules were retrieved termly

the viability of encapsulated cells and the biocompatibility of microcapsules were also examined.    Results   Both the membranes of ACA and APA microcapsules were electrolyte complexes

with enough mechanic strength. APA membranes were permeable to small molecule proteins such as trypsin

bovine serum albumin and impermeable to large molecule proteins such as immunoglobulin. The ACA and APA microcapsules remained intact after transplantation for 10 weeks. The retrieved 293 cells grew well after reculturing. After microcapsules entrapping 293 cells were retrieved. No sign for inflammation and pathological change was found in the anterior or posterior segment of New Zealand White rabbit and the important organs of SD mice.    Conclusion   The obtained results indicate that both the ACA microcapsules and APA microcapsules are proper cell carriers in transplantation.