TissueGene’s patented technology consists of allogeneic (donor) human cells that have been engineered to express specific therapeutic proteins. The company’s platform technology involves transducing cells with a retroviral vector engineered to express a particular therapeutic protein at a specific therapeutic level and duration of time. The modified cell lines are further selected and screened for a variety of cellular expression characteristics to minimize the patient’s immune response to the injected cells. These modified cells may then be mixed with unmodified cells to create the various product candidates. The product candidates are then injected directly into the damaged tissue, allowing the cells to act very much like living “protein factories” as the cells secrete therapeutic growth factors to induce repair and regeneration of tissue.