Presence Of Senescent Cells Research Articles

Role of replicative senescence in the progression of fibrosis in hepatitis C virus (HCV) recurrence after liver transplantation.

Although hepatitis C virus (HCV) recurrence is almost universal after orthotopic liver transplantation (OLT), the impact of viral infection on liver graft is highly variable and difficult to predict. Because of the possible relationship between replicative senescence (RS) and the accelerated development of liver fibrosis, we aimed to assess the potential role of RS in the severity of HCV-related chronic hepatitis recurrence after OLT. One hundred three liver biopsies from 56 patients receiving transplants for HCV-related cirrhosis were studied, including 30 revascularization biopsies and 52 and 21 biopsies performed during and beyond the first year of OLT, respectively. The presence of senescent cells in liver grafts was assessed by the senescence-associated beta-galactosidase (SA-beta-Gal) staining method. Chronic hepatitis was defined by fibrosis stage and necrotico-inflammatory activity grade using the METAVIR score. A total of 34 of the 103 (33%) frozen liver biopsies displayed SA-beta-Gal-positive cells, including 6 (20%) of the revascularization biopsies, 14 (34%) of the biopsies performed within the first year, and 10 (46%) of the biopsies performed beyond 1 year of follow-up. The presence of senescent cells in revascularization biopsies was significantly associated with the degree of ischemic necrosis at time of OLT (P = 0.01) and hepatitis C recurrence in the first year after OLT (P = 0.05). Furthermore, the presence of RS in the biopsy performed within the first year was associated with further development of fibrosis (P = 0.05). These data show that RS has a significant impact upon the course of liver transplantation, especially in the long-term progression of fibrosis observed in HCV-infected patients.

The role of replicative senescence in chronic allograft nephropathy

Strong evidence suggests that replicative senescence is involved in vivo because senescent cells have been detected in human tissues associated with physiological and pathological aging processes. Chronic allograft nephropathy (CAN) appears to be a major determinant of long-term survival in kidney transplantation. Several mechanisms are potentially involved; the aim of this study was to assess the impact of replicative senescence in CAN. Replicative senescent cells were detected on renal tissue cryosection using expression of a specific marker, senescence-associated β-galactosidase (SA-β-Gal) at pH 6. A total of 80 frozen renal samples (67 cases of CAN and 13 controls) were studied. To validate this marker, we measured in situ telomere length in cells expressing or not expressing SA-β-Gal using a validated quantitative fluorescence in situ hybridization technique. The presence of senescent cells was correlated with clinicopathologic data. Telomere length was significantly lower in cells expressing SA-β-Gal than in cells that did not. Replicative senescence was present in 45 out of 67 (67%) biopsy specimens and was significantly associated with the severity of CAN. No correlation with the notion of a previous episode of acute tubular necrosis, acute rejection, extrarenal epuration, duration of cold ischemia, and the delay between transplantation and biopsy was observed. However, the age of the donor, but not that of the recipient, was correlated with the occurrence of senescent cells. These results suggest that replicative senescence is a mechanism that might be involved in the development of CAN. The age of the donor appears to be the major determinant factor in replicative senescence.

Replicative senescence in normal liver, chronic hepatitis C, and hepatocellular carcinomas

There is growing evidence that senescent cells accumulate in vivo and are associated with the aging process in parallel with the progressive erosion of telomeres. Because recent data show that telomere shortening is involved in the pathogenesis of liver cirrhosis, we looked for replicative senescence cells in normal livers, chronic hepatitis C, and hepatocellular carcinoma (HCC). Replicative senescent cells were detected on liver tissue cryosections using expression of a specific marker, senescence-associated β-galactosidase, a cytoplasmic enzyme detected at pH 6. A total of 57 frozen liver samples (15 normal liver, 32 chronic hepatitis C, and 10 HCCs) were studied. Replicative senescence was graded as absent in 56% of cases (32 of 57) and present in 44% (25 of 57). Replicative senescence was considered present in 3 of 15 normal livers (20%), 16 of 32 chronic hepatitis cases (50%), and 6 of 10 HCCs (60%). In the group of nontumoral livers, the presence of senescent cells in liver was associated with older age (P =.03). In the group with chronic hepatitis C, fibrosis stage, but not activity grade, was significantly correlated with the accumulation of replicative senescent cells (P <.001). Finally, β-Gal staining in nontumoral tissue was strongly correlated with the presence of HCC in the surrounding liver (P <.001). These results suggest that chronic hepatitis C represents a relevant model of accelerated replicative senescence and that accumulation of replicative senescent cells predispose to HCC development. Detection of replicative senescent cells may then serve as a predictive marker of a hepatocellular carcinoma in the surrounding tissue. HUM PATHOL 32:327-332. Copyright © 2001 by W.B. Saunders Company