We used TTALEteloto monitor changes in telomere length in three established human aging systems: (1) Werner syndrome (WS) MSCs derived from WRN-deficient ESCs7,55,56 (Figure 6A and 6B, and Supplementary information, Figure S7A), (2) MSCs differentiated from iPSCs derived from Hutchinson-Gliford progeria syndrome (HGPS) patients (HGPS-GC-MSCs as an isogenic control line differentiated from LMNA gene-corrected HGPS-iPSCs)40,43,57 (Figure 6A and 6B, and Supplementary information, Figure S7B), and (3) hMSCs undergoing replicative senescence in culture (Figure 6A and 6B)58. This evidence concerns the gene WRN and Hutchinson-Gilford progeria syndrome.