A recent article in the Orange County Register reported that the first patient to receive human embryonic stem cell treatment for paralysis feels sensation in his legs. This is important support for the potential of stem Cell Therapy. The patient who came forward to report his progress to the press, was the first patient enrolled in a groundbreaking clinical study initiated by Geron Corporation. In January 2009, Geron made history by receiving clearance from the Food and Drug Administration (FDA) for the first clinical study of human embryonic stem cells in therapy. The Phase I study, for the treatment of spinal cord injury, involves injection of neural cells derived from human embryonic stem cells at the injury site 7-14 days after injury. The primary endpoint for the study is safety, but the secondary endpoint is efficacy, which includes sensation and neuromuscular control of the lower extremities. If the Phase I study is successful, a Phase II efficacy study will be launched. Human embryonic cells are collected from fertility clinics, where in vitro fertilization patients have donated embryos. According to Geron’s website, master banks of human embryonic stem cells approved for human use are the starting point for the manufacturing process. First, the human embryonic stem cells are expanded to increase the number of cells, and then they are differentiated into “a mixture of oligodendrocyte progenitor cells and other characterized cell types.” Finally, they harvest, formulate, fill, and cryopreserve the final product.Inventor of the treatment, Hans Keirstead, University of California at Irvine, was careful to say that this first patient’s experience is anecdotal and that it is too early to draw any conclusions resulting from the clinical study. Full results of the study will not be available until two years after the final patient undergoes treatment. However, he says that he is “thrilled” by the news. This is a very exciting development and success of this clinical trial would certainly pave the way for other human embryonic stem cell therapies, thus opening the door to many more treatments for previously untreatable diseases and conditions. It also solidifies the need for good animal-free manufacturing practices for stem cell therapies. Stem cells are frequently grown using animal components, including fetal bovine serum, but there is always a concern about adventitious infectious agents contaminating the stem cells. Animal components have been discouraged and largely removed from biopharmaceutical manufacturing, but they still are prevalent in stem cell processes. As stem cell therapies see successful clinical trial results and move beyond the clinic to FDA-approved therapies, animal component manufacturing concerns will need to be addressed and removal of these products from manufacturing will become a priority.