Microinjection Turns a Tissue Culture Cell into a Test Tube

Abstract

The demand for techniques to investigate biologically important macro-molecules (DNA, RNA, proteins) within the living cell has increased continually with our growing competence to purify, analyze, and modify them in vitro. Since these molecules are not taken up readily by a cell unless a specific recognition — internalization mechanism exists, ways to bypass cellular membranes efficiently without affecting the viability of a target cell have had to be found. For tissue culture cells, this goal has been achieved by an approach which uses glass micropipettes for physical injection of single culture cells. This microinjection technique was developed in our laboratory initially for the transplantation of cell nuclei (Graessmann 1968, 1970) and shortly thereafter adopted for the transfer of biologic macromolecules: for example, mRNA was injected into and translated in a foreign cell (Graessmann and Graessmann, 1971).