Degradable three-dimensional porous scaffolds applicable as cell carriers for bone tissue engineering were developed by an innovative solvent casting/particulate leaching technique from poly(L-lactide-co-glycolide) (PLG). Three types of PLG scaffolds were prepared, and these had the same high porosity (83%) but increasing diameter of the pores (180-200 microm, 250-320 microm, and 400-600 microm) and increasing pore interconnectivity. The colonization of the scaffolds with human osteoblast-like MG 63 cells was then studied in vitro in a conventional static cell culture system. The number of cells growing on the scaffolds on days 1 and 7 after seeding was highest in the material with the largest pore diameter, but on day 15, the differences among the scaffolds disappeared. Confocal microscopy revealed that on day 1 after seeding, the cells penetrated to a depth of 490 +/- 100 microm, 720 +/- 170 microm, and 720 +/- 120 microm into the scaffolds of small, medium, and large pore size, respectively. Incorporation of bromodeoxyuridine into newly synthesized DNA and the concentration of vinculin, beta-actin, osteopontin, and osteocalcin in cells on the scaffolds of all pore sizes were similar to the values obtained on standard tissue culture polystyrene, which indicated good biocompatibility of the scaffolds. These results suggest that all scaffolds could serve as good carriers for bone cells, although the quickest colonization with cells was found in the scaffolds with the largest pore diameter from 400 to 600 microm.