Scientists in the US have found a novel way of defining how old you are at a molecular level. The hope is that the technique could be used to predict how tissues respond to treatments or surgery.
The group of researchers at the University of North Carolina found that measuring the concentration of a protein - called p16INK4a - in the blood was indicative of the molecular age of a tissue. To investigate this, the team analysed blood samples from 170 people who also answered questions about their health and lifestyle. They found that not only were the levels of the protein in the blood representative of age, but that they were also linked to certain behaviours which are known to speed up the ageing process, such as lack of physical exercise and smoking.
Scientists were initially interested in p16INK4a due to its role in suppressing the development of cancer. It is present in the cells of the immune system - T-cells - which help fight disease and repair tissues that are damaged.
It is hoped that once this technique is perfected as a simple blood test, it could provide a way of assessing how healthy tissues are and their suitability for surgery or responding to drugs.
Dr Norman Sharpless, a researcher on the project, said that 'this is a major step toward a practical tool to clinically determine a person's actual molecular, as opposed to just their chronological, age'. He added: 'Although we don't know whether this test is a good reflection of cellular age in all types of human tissues, we believe it is a first step toward a better understanding of issues like the suitability of organs for transplantation, how well patients are likely to recover after surgery or the future toxicity of chemotherapy for cancer patients'.
Another interesting finding from the study was that the protein levels were not linked to obesity, as Sharpless had expected based on previous research that showed that limiting calorie intake slows the ageing process.
The current way of measuring the age of tissues is by measuring the length of telomeres - strands of DNA that protect chromosomes from damage and grow with time. Professor Tim Spector, from King's College London, has carried out much research into relating telomere length to age. He says: 'p16INK4a clearly has potential for use as a novel marker of biological ageing', but states that much more work is needed before it is said to be a better marker that the existing technique.