Tissue dispersion, cell harvest and fluid suspension culture by the use of bacterial neutral protease.

Bacterial neutral protease of Bacillus polymyxa was found to disperse mammalian tissues and cells. Primary cell cultures were obtained from several tissues after treatments with 200 to 2,000 Kunitz unit per ml of this protease in either a phosphate buffer solution, a balanced salt solution or a tissue culture medium supplemented with serum. Monolayer cultures wither in their early passage levels or of established strains were harvested by a treatment with this protease, and proliferated again in monolayer after its removal. A growing culture of strain L-929 was kept in monodisperse suspension in the presence of this protease. In contrast to trypsin, this protease was found active in the presence of serum, stable during incubation and scarcely injured cells.