Accumulation of DNA damage in hematopoietic stem and progenitor cells during human aging.

Background: Accumulation of DNA damage leading to adult stem cell exhaustion has been proposed to be a principal mechanism of aging. Here we tested this hypothesis in healthy individuals of different ages by examining unrepaired DNA double-strand breaks (DSBs) in hematopoietic stem/progenitor cells matured in their physiological microenvironment.

Methodology/principal Findings: To asses DNA damage accumulation and repair capacities, γH2AX-foci were examined before and after exposure to ionizing irradiation.

Short telomeres in aggressive non-Hodgkin's lymphoma as a risk factor in lymphomagenesis.

Objective: Telomeres cap chromosomal ends and help to maintain chromosomal integrity. Telomere shortening may result in chromosomal instability and, ultimately, malignant transformation of cells. It has not been systematically studied whether patients with malignancy have shortened telomeres in their normal, nontransformed cells, which might point to a preexisting disposition for chromosomal instability.

Influence of telomere length on short-term recovery after allogeneic stem cell transplantation.

Objective: Telomeres shorten in somatic cells during aging and states of increased turnover, including hematopoietic stem cell transplantation. Fast hematopoietic recovery is critical for the patients' course after hematopoietic stem cell transplantation. It is unknown whether telomere length in hematopoietic stem cells (HSCs) predicts short-term hematopoietic recovery.