Cell processing method and cell processing apparatus

A cell processing method comprising:

• preparing a cell suspension containing a cell to be processed and a target substance, wherein the cell to be processed is a cell which is selected from a cell group including cells in a proliferation process, and which has a cell diameter larger than a mode in a cell diameter distribution of the cell group;
• and
• introducing the target substance into the cell to be processed by allowing a shear force to act on the cell to be processed, wherein allowing a shear force to act comprises ejecting the cell suspension from an orifice by a liquid injection head, wherein the orifice is included in the liquid ejection head;
• wherein the liquid ejection head includes:
• a plurality of the orifices arrayed in a row;
• a common liquid chamber having a shape extending along the row of the orifices;
• and
• a plurality of supply flow paths each configured to communicate the common liquid chamber to a corresponding one of the orifices,
• wherein the common liquid chamber is configured so that a mixed liquid containing the cell group and the target substance is supplied to each of the supply flow paths while flowing from one end side of the row of the orifices to another end side thereof,
• wherein a connection portion between the common liquid chamber and each of the supply flow paths has arranged therein a pillar-shaped nozzle filter,
• wherein the nozzle filters
• have a smaller pillar diameter on a downstream side of a flow of the mixed liquid in the common liquid chamber than on an upstream side thereof, and
• have, on a most upstream side of the flow of the mixed liquid in the common liquid chamber, a pillar diameter of such a size that the cell to be processed cannot be supplied to a corresponding one of the supply flow paths, and
• have, on a most downstream side of the flow of the mixed liquid in the common liquid chamber, a pillar diameter of such a size that the cell to be processed can be supplied to a corresponding one of the supply flow paths, and
• wherein the cell to be processed is selected from the cell group through utilization of the nozzle filters.