gold standard, two-step liver/liver lobe perfusion procedure". I have done perfusions myself and they obviously vary in each lab somewhat. I have no details about the exact procedure they used, but the cells they sent us were of very high viability and we were able to get organoids out of them (at least, from the young subjects).

Human specimens

Frozen human hepatocyte samples were purchased from Lonza Walkersville Inc. Whole livers for hepatocyte isolation were obtained with the informed consent of families of registered organ donors. The obtained liver organs were rejected for transplant due to either lack of a donor match or morphological alterations (e.g., tearing and hematoma). All 12 selected hepatocyte donors were healthy participants of various age, gender, and ethnicity (table S1) without any liver cancer or other liver pathology history. These cells had been isolated using a gold standard, two-step liver/liver lobe perfusion procedure. Cells were suspended in 2 to 5 ml of media and counted with Trypan blue to estimate viability (higher than 80%), and frozen in dimethyl sulfoxide/liquid nitrogen (www.lonza.com). One specimen of frozen human neonatal LSCs from a 1-year-old donor was purchased from Kerafast Inc. (www.kerafast.com). These cells had been derived by the Sherley laboratory (Boston, MA, USA) and characterized to confirm their stem cell identity (39–41).