Primary suspension culture of calf anterior pituitary cells on a microcarrier surface

In order to achieve a steady-state primary culture system for mammalian cells, with the potential to eventually correlate and control cell function and growth, a serious evaluation of various suspension systems was made. Calf anterior pituitary cells were employed as a differentiated cell type and successfully cultivated in a microcarrier suspension culture system. DEAE-Sephadex was demonstrated to be a satisfactory type of microcarrier. The cells readily attached to the bead and, after a short lag period, they actively proliferated on the bead surface to yield growth of a predominantly epithelial cell type. Under specific conditions the microcarrier supported primary cell growth up to levels of 2 × 10⁶ cells per ml. High bead concentrations inhibited cell growth. The inhibition could be overcome by using proportionately higher cell inoculum so that a concentrated culture with 5 × 10⁶ cells per ml was achieved. The inhibitory effect of high bead concentration was found to be due to the absorption of serum protein and certain growth enhancing factors. The fact that the growth enhancing factors were released from cells during the period of trypsinization and were both thermostable and nondialyzable, seems to suggest one approach to a dialysis culture system. In addition, relatively trauma-free primary cell cultures can be achieved by using explant culture without prior trypsinization. In microcarrier suspensions direct growth of primary rat mammary tumor cells was also demonstrated.