Blog Category: Free Radical Biology and Medicine

Click here to read the full study in the journal: Free Radical Biology and Medicine

Cellular redox balance plays a significant role in the regulation of hematopoietic stem-progenitor cell (HSC/MPP) self-renewal and differentiation. Unregulated changes in cellular redox homeostasis are associated with the onset of most hematological disorders. However, accurate measurement of the redox state in stem cells is difficult because of the scarcity of HSC/MPPs. Glutathione (GSH) constitutes the most abundant pool of cellular antioxidants. Thus, GSH metabolism may play a critical role in hematological disease onset and progression.

A major limitation to studying GSH metabolism in HSC/MPPs has been the inability to measure quantitatively GSH concentrations in small numbers of HSC/MPPs. Current methods used to measure GSH levels not only rely on large numbers of cells, but also rely on the chemical/structural modification or enzymatic recycling of GSH and therefore are likely to measure only total glutathione content accurately.

Here, we describe the validation of a sensitive method used for the direct and simultaneous quantitation of both oxidized and reduced GSH vialiquid chromatography followed by tandem mass spectrometry (LC-MS/MS) in HSC/MPPs isolated from bone marrow. The lower limit of quantitation (LLOQ) was determined to be 5.0 ng/mL for GSH and 1.0 ng/mL for GSSG with lower limits of detection at 0.5 ng/mL for both glutathione species. Standard addition analysis utilizing mouse bone marrow shows that this method is both sensitive and accurate with reproducible analyte recovery.

This method combines a simple extraction with a platform for the high-throughput analysis, allows for efficient determination of GSH/GSSG concentrations within the HSC/MPP populations in mouse, chemotherapeutic treatment conditions within cell culture, and human normal/leukemia patient samples. The data implicate the importance of the modulation of GSH/GSSG redox couple in stem cells related diseases.

If you’re an older adult, a 30-minute workout may not be as effective, even at the cellular level, as it was when you were younger. According to a new study, age may play a significant role in cell’s ability to respond to that activity.

The study, led by Dr. Tinna Traustadóttir of Northern Arizona University, was recently published in Free Radical Biology and Medicine, a journal of the Society for Redox Biology and Medicine (SFRBM).

In the study, a group of men age 18-30 were tested against a group of older men 55 years of age and older.  Study participants were generally healthy, non-smokers, who were not taking antioxidant supplements in excess of a multivitamin, or any non-steroidal anti-inflammatory drugs for two weeks leading up to their study visit.

The two groups cycled for 30-minutes, with blood being drawn at six time points to test cell function and antioxidant response. For this study, the exercise intensity was set relative to the individual’s maximal aerobic capacity as determined by a maximal oxygen consumption test during screening. It is known that older adults have a reduced aerobic capacity compared to young, thus this allowed the group to maintain the same relative workloads between young and old test groups.

“Through this study we were able to determine that an individual’s antioxidant response to exercise becomes suppressed with age,” said Dr. Traustadóttir an Associate Professor at Northern Arizona University and SFRBM Member. “Exercise is effective and critical for people of all ages, but this study shows that older adults do not achieve the same beneficial cellular responses as younger adults from a single bout of moderate exercise.”

The findings indicate a single session of submaximal aerobic exercise is sufficient to activate a important group of antioxidant genes at the whole cell level in both young and older adults. However, nuclear import of Nrf2, the regulator for this group of antioxidant genes, is impaired with aging. Nuclear import is required for Nrf2 to access the antioxidant gene targets. Together these data demonstrate for the first time the weakening of Nrf2 activity in response to exercise in older adults.

Traustadóttir’s ongoing research aims to identify molecular processes responsible for age-related cellular changes. By better understanding the molecular signals promoting beneficial effects of exercise, definitive recommendations could be made for improving the body’s reaction to oxidative stress, which could lower the risk for many chronic diseases.