Patent ID: 8119368

Claim:
Process for culturing of cells in a reactor in suspension in a cell culture medium, comprising: circulating a cell culture through a separation system comprising a filter, wherein the cell culture comprises eukaryotic cells, a biological substance produced by the cells, and a cell culture medium, wherein at least one cell culture medium component is fed to the cell culture; wherein the cell culture is circulated through the filter in an alternating tangential flow; and wherein the separation system separates the biological substance from substances having a lower molecular weight than the biological substance; retaining or feeding back the biological substance into the reactor, wherein the cells are cultured to have a viable cell density of at least 10×10 6 cells/mL; and harvesting the biological substance from the cells and/or from the cell culture; wherein the biological substance is present in the cell culture at a concentration of at least 5 g/L prior to the harvesting.