– Induced pluripotent stem cells (IPS) can be derived from frozen blood. IPS are “ethical” because they are not harvested from fetuses. Until now, IPS cells were made “regressing” plugs of skin. According to a study published by ‘Cell Stem Cell’, it is much easier to use frozen blood as a source , because to collect a blood sample of 20 mL is much less problematic than a skin biopsy. .