This application describes an apparatus and a method for the treatment of a damaged lung, heart, or other organ or tissue using cells contained in the apparatus and a liquid interface that allows communication with the circulation of the damaged organ or tissue. The apparatus can be used to treat the organ inside or outside the body. The apparatus is designed to sit outside the body but a similar apparatus is envisioned that is implantable. The apparatus contains a porous material or matrix that the cells are grown on, and the volume of the apparatus provides that it can contain a therapeutically useful number of cells in the range 0.5 x 10e6 to 200 x 10e6.
