Multiple membrane microencapsulation

Living tissues, such as hybridoma cells or insect cells suspended in a water soluble gelling agent, are microencapsulated in a double polymeric membrane microcapsule. The inner membrane is of a high molecular weight cut-off to permit outward diffusion of the gelling agent and also expansion of the microcapsule before formation of the outer membrane which is a relatively lower molecular weight cut-off. The living cells in the dual membrane microcapsule may be grown to an intracapsular density which is significantly higher than that which can be achieved by using single-membrane capsules. The recovery of intracapsular protein product (produced by the encapsulated cells) is also significantly higher and the loss of product through the membrane wall markedly lower for the dual membrane capsule than for the single membrane capsule.