Human fetal fibroblasts (Stanford University)

The limbs were minced and digested in trypsin, to create single-cell suspensions. The cells were plated on tissue culture dishes in mouse embryonic fibroblast (MEF) medium comprised of Dulbecco’s modified Eagle’s medium (DMEM) containing high glucose, calf serum, β-mercaptoethanol, non-essential amino acids, sodium pyruvate and penicillin/streptomycin.