A technique for the microinjection of macromolecules into viable chromaffin cells in culture

A technique is described by which macromolecules can be microinjected into chromaffin cells in monolayer culture. This technique employs erythrocyte ghosts as the vehicles for microinjection, phytohemagglutinin, a plant lectin, as an attachment agent, and polyethylene glycol as the fusagen. High erythrocyte ghost-chromaffin cell fusion indices have been obtained, with an average of 46.2 +/- 1.1% (n = 14) of the total chromaffin cell population efficiently injected. Cell viability is well maintained during and after fusion with an average cell loss of 12 +/- 0.4% (n = 14) of the total cell population. The functional parameters which characterize the chromaffin cells in culture are unaltered after fusion-induced microinjection. The endogenous catecholamine content, the uptake of exogenous catecholamines via the high-affinity uptake mechanism for catecholamines, as well as the cell's response to various secretagogues remain unchanged. This procedure which allows a large number of cultured cells to be injected rapidly without significant loss of cell viability will aid in the study of the molecular and cell biology in this system.