The separation of harvested cells from microcarriers: a comparison of methods

Two techniques are described which have been designed to separate harvested cells from microcarriers. The requirements of efficient recovery and high viability of the cells are met by both procedures. Differences both in size and density between cells and microcarriers allow separations which are based on differential centrifugation or filtration. After trypsinizing the cells from the microcarriers, separation was performed by either ; a) low-speed centrifugation on Ficoll-Paque or, b) filtration through nylon meshes. The methodologies for both techniques are presented. Up to 78% of the total cells were recovered by discontinuous gradient centrifugation using Ficoll-Paque. similar results were obtained when separating Vero, BS-C-1 and MRC-5 cells from Cytodex 1, Cytodex 2 and Cytodex 3 microcarriers. Equally high recoveries were obtained by filtration through an 88 micron pore size nylon mesh. Data are presented for the separation of both Vero and HeLa cells from all 3 types of microcarriers after filtration through 53 and/or 88 micron meshes. Greater than 92% viability of the recovered cells was consistently obtained and their growth properties upon subsequent reculturing were unaffected by either separation procedure. Differential sedimentation by unit gravity provides adequate cell recovery for many applications, but yields are significantly increased by using one or other of the methods described here. Both techniques are rapid and efficient. In addition, differential centrifugation provides a concentrated suspension of the recovered cells, while the nylon meshes for filtration are reusable and can be autoclaved at least 5 times.(ABSTRACT TRUNCATED AT 250 WORDS)