hiPSCs were gifted by Professor Zhiguo Chen (Cell Therapy Center, Beijing Institute of Geriatrics, Xuanwu Hospital Capital Medical University) (18 (link)) and were maintained in mTeSR1 medium (Stemcell Technologies, Inc.; cat. no. 85850) in 6-well cell culture plates (Costar; Corning, Inc.; cat. no. 3516) coated with 1% vol/vol human embryonic stem cell-qualified Matrigel (Corning, Inc.; cat. no. 354277) in a 37˚C incubator at 5% CO2. hiPSCs were passaged in Dissociation Solution for human embryonic stem cells/iPSCs (ReproCELL, Inc.; cat. no. RCHETP002) at a 1:3 ratio every 7 days, according to the manufacturer's protocol.