Comparative assessment of telomere length before and after hematopoietic SCT: role of grafted cells in determining post-transplant telomere status

Our objective was to characterize the role of grafted cells in determining telomere length (TL) after hematopoietic SCT (HSCT). A total of 20 patients undergoing autografts had PBSC collected after two sequential mobilization courses: TL in the first collection was significantly longer than in the second. For their autografts, 10 patients used PBSC from the first collection and 10 from the second. TL was also investigated before and after HSCT and on the graft in 10 allogeneic HSCT. After autografting, patients receiving PBSC from the first collection had BM TL reflecting that of grafted cells (median bp: 7730 on PBSC vs 7610 on post-HSCT BM, P=NS) and significantly longer than TL of the second collection; analogously, patients autografted with PBSC from the second collection had BM TL reflecting that of grafted cells (7360 on PBSC vs 7120 on post-HSCT BM, P=NS) and significantly shorter compared with the first collection. In the allograft setting, eight patients had their pre-transplant TL significantly shorter than donor PBSC (5960 vs 7110; P=0.0005); following HSCT, BM TL (median 7380 bp) was identical to that of the graft (P=NS). We conclude that grafted cells have a major role in determining TL after HSCT.