It is simple, when more embryonic research is being conducted, then more cells are required to do the research.
Existing cell lines will eventually become contaminated and new ones will have to be created. Contamination is almost impossible to prevent over time. Also, human cell lines are not immortal. After a certain number of cell divisions they die off cease to divide.
So, it is obvious that an increased demand for embryonic stem cells would result in an increased demand for embryos.
The cells are derived from the H1 human embryonic stem cell line, which was created before August 9, 2001. Studies using this line qualify for U.S. federal research funding, although no federal funding was received for the development of the product or to support the clinical trial.
Geron's H1 hESC master cell bank is fully qualified for human use and was shown to be karyotypically normal and free of measurable contaminants of human or animal origin. Production of GRNOPC1 from undifferentiated hESCs in the master cell bank uses qualified reagents and a standardized protocol developed at Geron over the past three years. Each manufacturing run of GRNOPC1 is subjected to standardized quality control testing to ensure viability, sterility and appropriate cellular composition before release for clinical use. GRNOPC1 product that has passed all such specifications and has been released is available for the approved clinical trial. The current production scale can supply product needs through pivotal clinical trials. The existing master cell bank could potentially supply sufficient starting material for GRNOPC1 to commercially supply the U.S. acute spinal cord injury market for more than 20 years.