It sounds like preclinical work is proceeding well at Tengion: "Growing a replacement organ for a patient using his or her own cells presents a new option. After a bladder biopsy is obtained from a patient, bladder progenitor cells are grown in culture and seeded on a biodegradable bladder-shaped scaffold made from collagen and/or polyglycolic acid. The neo-organ is then implanted into the patient. The neo-organ is then implanted into the patient. Fourteen large mammals [were] implanted with the neo-bladder construct and within six months, structure and pharmacological characteristics of the neo-bladder were similar to the native bladder. There was no evidence of abnormal tissue development, immune response or evidence of systemic response to the neo-bladder regeneration. Results suggest that the new organ had successfully and safely regenerated. ... This treatment option essentially regenerates the patient's own bladder, reducing the risk of rejection and the need for immunosuppressant drugs. If successful in human clinical trials, patients should expect to regenerate normal bladder structure and function."