Telomere length plays an important role in regulating the proliferative capacity of cells, and serves as a marker for cell cycle history and also for their remaining replicative potential. Mesenchymal stromal cells (MSC) are known to be a significant cell source for therapeutic intervention and tissue engineering. To investigate any possible limitations in the replicative potential and chondrogenic differentiation potential of fibroblast growth factor-2-expanded MSCs (FGF(+)MSC), these cells were differentiated at various population doublings (PDs), and telomere length and telomerase activity were measured before and after differentiation. FGF(+)MSC cultured at a relatively low density maintained proliferation capability past more than 80 PD and maintained chondrogenic differentiation potential up to at least 46 PD and long telomeres up to 105 PD, despite expressing low levels of telomerase activity. Interestingly, upon chondrogenic differentiation of these cells, telomeres showed a remarkable reduction in length. This shortening was more extensive when FGF(+)MSC of higher PD levels were differentiated. These findings suggest that telomere length may be a useful genetic marker for chondrogenic progenitor cells.

We investigated the responses of the hypothalamic-pituitary-adrenal (HPA) axis during experimental colitis induced by intracolonic administration of 2,4,6-trinitrobenzenesulfonic acid in the rat. On days 3 and 7 after induction of colitis, the corticotropin-releasing hormone (CRH) mRNA level in the parvocellular paraventricular nucleus (pPVN) of the hypothalamus was reduced, the plasma ACTH level remained at the basal level, and the plasma corticosterone (Cort) level was high. Induction of colitis on day 3 after adrenalectomy with Cort pellet replacement (ADX + Cort) resulted in a marked increase in CRH mRNA on day 7 after induction of colitis compared with noncolitic ADX + Cort animals. Pair feeding to match the food intake of the colitic animals resulted in no significant change in CRH mRNA in the pPVN, plasma ACTH, and Cort compared with healthy control animals. These findings indicated that CRH mRNA expression in the pPVN was inhibited by glucocorticoid feedback during this experimental colitis, and the decrease in food intake during colitis was not simply responsible for the expression of CRH mRNA. It is inferred that the HPA axis including the CRH level in the pPVN is altered in patients with inflammatory bowel disease.

Our previous report demonstrated a good correlation between high telomerase activity of cancer tissues and a poor prognosis of patients with colorectal cancers, except for several cases. To elucidate the additional factors that contribute to patient prognosis, the correlation among the expression levels of telomere binding proteins (TBP), the lengths of telomeres, the lengths of telomere 3¢-overhang (3¢-OH) and telomerase activity in 106 paired colorectal cancer and corresponding noncancerous mucosa (NCM) specimens were examined. The expression levels of eight TBP genes (TRF1, TRF2, TIN2, TANK1, TANK2, POT1, RAP1 and TPP1) were analyzed. Among the 106 cases, 35 cases had shortened telomeres (<7 kb), 15 had shortened 3¢-OH (3¢-OH length ratio of cancer/NCM <0.5) and 88 were classified as telomerase-activated cancers (activity ratio of cancer/NCM >2). Comparison between NCM and cancer in each case showed that all TBP except for POT1 were downregulated in cancers. A survival analysis using a Cox proportional hazard model showed that the survival rate of the telomerase-activated cases with shortened 3¢-OH and that of telomerase-inactivated cases were significantly better than that of telomerase-activated cases without 3¢-OH shortening, that is, restored or maintained 3¢-OH (P = 0.018). In the telomeraseactivated cancers, the length of 3¢-OH was significantly correlated with the expression levels of POT1. Elongation of telomeric overhang by telomerase, which might be regulated by POT1, may contribute to the increase of malignant potential in colorectal cancers. (Cancer Sci 2011; 102: 330-335) T he ends of chromosomes, named telomeres, are characterized by guanine-rich tandem hexamers (5¢-TTAGGG-3¢) with an average length of 5-15 kb and they serve as protective caps.(1,2) During DNA replication in cell division, telomeres gradually shorten at a rate of 50-200 bp as a result of the incomplete replication of linear chromosomes, the so-called 'end-replication problem'.(3) The telomeres terminate in a 3¢-single-stranded overhang of 12-300 bp, that is, ''telomere 3¢-overhang (3¢-OH)'' of the G-rich strand, which can be extended by telomerase in the S phase, followed by fill-in of the C strand in the late S phase.(4) Telomerase is a ribonucleoprotein that catalyzes de novo synthesis and elongation of telomeric repeats at chromosomal ends using an intrinsic RNA template in eukaryotic cells with an extended lifespan. The telomere overhang folds back into the D-loop of the duplex telomeric DNA to form a protective ''T-loop'' that prevents degradation by exonucleases or processing as damaged DNA.(5) This loop hides the 3¢ end also from telomerase. Furthermore, the telomeric repeats are bound to a large protein complex called ''shelterin'',which involves several telomere binding proteins (TBP). This complex is proposed to regulate telomere length, telomere protection and other cell functions such as proliferative activity.(5) When the telomere length shortens to a limited length, cells fall into senescence due to cleavage of ...

Giant cell tumors of bone (GCTB) are rare sarcomas with a high rate of unpredictable local relapse. Studies suggest that surgical methods affect recurrence, supporting the idea that local disease develops from re-growth of residual cancer cells. To identify early prognostic markers of individual risk of recurrence, we evaluated the effect of post-surgery fluids from a cohort of GCTB patients on growth of primary and established sarcoma cell lines, and mice xenograph. Post-surgery fluids increased cell growth and enhanced expression of CD44 ++ , the principal receptor for the extracellular matrix component hyaluronan and the mesenchymal stem marker CD117 +. Cancer cells became highly invasive and tumorigenic, acquiring stemness properties, and activated AKT/mTOR pathway. Prolonged stimulation with post-surgery fluids down-regulated the mesenchymal gene TWIST1 and Vimentin protein, and transdifferentiated cells into tubule-like structures positive to the endothelial markers VE-Cadherin and CD31 +. In mice, post-surgery fluids gave rise to larger and more vascularized tumors than control, while in patients AKT/mTOR pathway activation was associated with recurrence by logistic regression (Kaplan-Meier; P<0.001). These findings indicate that post-surgery fluids are an adjuvant in mechanisms of tumor regrowth, increasing stem cell growth and AKT/mTOR activity.

Objective To evaluate the effects of localized irrigation with epinephrine saline after endoscopic retrograde cholangiopancreatography (ERCP). Patients and Methods