A humanized system to expand in vitro amniotic fluid-derived stem cells intended for clinical application

Background aims.The amniotic fluid is a new source of multipotent stem cells with therapeutic potential for human dis-eases. In agreement with the regulatory requirement to reduce and possibly to avoid animal-derived reagents in the cultureof cells intended for cell therapy, bovine serum, the most common supplement in the culture medium, was replaced byhuman platelet-derived growth factors.Methods.We tested a new culture medium to expand monolayers of human amni-otic fluid stem cells (hAFSC) for clinical use.The AFSC were isolated by c-Kit selection and expanded in media supplementedwith either bovine serum or a human platelet lysate (Lyset).Results.We compared proliferation kinetics, colony-formingunit percentage, multilineage differentiation, immunophenotypic characterization and inhibition of peripheral blood mono-nuclear cell proliferation of the two AFSC cell cultures and we found no significant differences. Moreover, the karyotypeanalysis of the cells expanded in the presence of the platelet lysate did not present cytogenetic abnormalities andin vitroandin vivostudies revealed no cell tumorigenicity.Conclusions.Platelet derivatives represent a rich source of growth factorsthat can play a safety role in the homeostasis, proliferation and remodeling of tissue healing. We propose human plateletextracts as a preferential alternative to animal serum for the expansion of stem cells for clinical applications