Encapsulated cells producing viral particles

A process for preparing encapsulated retroviral packaging cells which produce retroviral particles, comprising capsules having a porous capsule wall which is permeable to said retroviral particles, comprising suspending the cells producing retroviral particles in an aqueous solution of polyelectrolyte, whereafter the suspension in the form of preformed particles is introduced into a precipitation bath containing an aqueous solution of a counter-charged polyelectrolyte.

A method for delivery of a gene into or close to the site of a target organ or cell wherein the gene is expressed comprising:

• a) culturing encapsulated retroviral packaging cells which produce retroviral particles, comprising capsules having a porous capsule wall which is permeable to said retroviral particles wherein the genome of the retroviral particles express the expression product of the gene, in a suitable medium, and
• b) locally administering the encapsulated cells into or near the site of the target organ or cell of a living animal body, including a human
• wherein infectious retroviral particles are produced and released from the capsules and the retroviral particles infect the target organ or cell, thereby delivering the gene to the target organ or cell wherein the gene is expressed.