Where do the stem cells come from?

Where do the stem cells come from? How are they processed and are they in anyway purified? Should there be a concern about them forming into the wrong type of cell and possibility resulting in the formation of a tumor?

The neural stem cells come from the neural system of the fetus (less than 4 months old) which are collected and further processed and manufactured by the National Industrial Base of Stem Cell Technology, i.e., the cells are separated, expanded in-vitro and purified under the strictest and most effectively controlled environment before they are sealed in vials for clinical implantation. These stem cells will not differentiate into any other kind of cells except neuron precursors.

To date, we have treated just over 1,000 patients and in the past 5 years of administering the stem cell treatment there have been no cases of cell rejection, or the development of tumors.