The biotech company Bioviva has claimed that its CEO, Elizabeth Parrish, has successfully had her telomeres lengthened by one of the company’s experimental gene therapies. Telomeres sit on the end of chromosomes and shorten as we age. Bioviva has claimed on its website that the telomeres of Parrish’s white blood cells had lengthened by “approximately twenty years”. She is the only person to be given the therapy.
Dr. Rita Effros, Professor of Pathology & Laboratory Medicine, David Geffen School of Medicine at University of California, Los Angeles (webpage):
Expertise: Telomere/telomerase dynamics within the human immune system, effects of chronic viral infections and aging on telomere length.
“There are several important technical issues that could explain the apparent telomere lengthening reported for Elizabeth Parrish. The overarching problem is that peripheral blood (blood that is circulating around the body) contains a mixture of many different cell types with disparate telomere lengths. For example, long-lived T cells have shorter telomere lengths than newly generated naïve cells; and cells which have reached their maximum limit of cell divisions have shorter telomeres than any other cell type. Thus, a simple change in the proportion of different cell types within the peripheral blood could easily explain the data.
“A change in the proportion of cell types within the peripheral blood could be due to a number of factors: immunological encounters over the year; environmental/lifestyle effects such as exercise, which affects the trafficking of immune cells from blood to certain organs; or even hormonal status (i.e., the time of the month). It is known, for example, that estrogen increases the activity of a telomere-extending enzyme, telomerase, in T cells that are involved in an ongoing immune response.
“A second issue with the data is that the telomere length measurements were performed in different experiments. The proper way to compare different time points for telomere lengths would be to cryopreserve (freeze) the two samples, and run the telomere length measurements side-by-side under identical experimental conditions.
“Finally, it is well-known that telomere lengths of different tissues within the same person may differ dramatically. Peripheral blood (which contains only 2% of the total body lymphocyte population) is the most easily accessible tissue for telomere measurement, but may not be the true biomarker of age. Indeed, the recent Geroscience Summit at the NY Academy of Sciences concluded that one of the urgent scientific goals is to identify a reliable biomarker of human age. It was clear from the discussion among experts in the field that peripheral blood telomere length does not constitute such a marker.”
Dr. Bradley Johnson, Associate Professor, Pathology and Lab Medicine, University of Pennsylvania (webpage):
Expertise: The biology of human aging and cancer, and how they are influenced by telomere maintenance and dysfunction.
“It’s hard to assess how accurate the results are without knowing details of how the measurements were performed. Publishing the findings in a high quality peer-reviewed journal would certainly be helpful.
“However, a few things can be said with some degree of certainty. First, telomere length measurements typically have low precision, with variation in measurements of around ten percent, which is in the range of the reported telomere lengthening apparently experienced by Elizabeth Parrish. Second, the telomere measurements were performed on peripheral blood white blood cells (WBCs) and, within any given person over brief periods of time, WBC telomeres could lengthen or shorten depending on everyday circumstances (e.g. viral infection).
“More generally, we don’t yet know to what extent telomere dysfunction contributes to human aging. However, there is a substantial body of evidence that points to important roles for telomeres, and so my guess is that telomere lengthening may be of significant benefit to people under the right circumstances.
“Artificial telomere lengthening in normal laboratory mice has been shown to improve health and extend median lifespan. Effects on people might be even more pronounced, but might also be detrimental. In particular, there are good reasons to think that humans evolved systems of telomere shortening to stave off cancer until later ages, and therefore artificial lengthening of telomeres could increase cancer risk, especially in younger individuals.
“Is ‘reversing aging’ a meaningful concept, i.e. is it possible? I think it is. There are numerous systems that naturally repair the damage that our molecules, cells and tissues encounter every day. For example, the healing of a skin wound. You can think of aging as the inability of the body to fully reverse all of the damage encountered over a lifetime. But there are many reasons to think that repair mechanisms can be enhanced to slow or even reverse aspects of aging. Whether artificial lengthening of telomeres in people will provide such benefits is not known, but is worth investigating.”
Declared interests (see GENeS register of interests policy):
No interests declared.