Underwood J, Rahim M, West C, Britton R, Skipworth E, Graves V, Sexton S, Harris H, Schwering D, Sinn A, Pollok KE, Robertson KA, Goebel WS, Hege KM. How old is too old? In vivo engraftment of human peripheral blood stem cells cryopreserved for up to 18 years - implications for clinical transplantation and stability programs. World J Stem Cells 2020; 12(5): 359-367 [PMID: 32547684 DOI: 10.4252/wjsc.v12.i5.359]