Perhaps the secret to the Fountain of Youth has been hiding inside of us all along - with the emphasis truly on the "inside" part of the equation.

Scientists at the VU University Medical Center in Amsterdam, the Netherlands, did an in-depth study on blood and tissue samples from Hendrikje van Andel-Schipper, who passed away in 2005 at the age of 115, the oldest woman in the world at the time. Their research revealed van Andel-Schipper's death was specifically caused by exhaustion of blood stem cells.

Among the conclusions the research found is that the human lifespan may ultimately be limited by the capacity for stem cells to keep replenishing tissues day in and day out. The study further suggests that once the stem cells reach a state of exhaustion that imposes a limit on their own lifespan, they  begin to gradually die out and diminish the body's capacity to keep regenerating vital tissues and cells, such as blood.

"Is there a limit to the number of stem cell divisions, and does that imply that there's a limit to human life?" the lead researcher on the study, Henne Holstege of the VU University Medical Center in Amsterdam, asks. "Or can you get round that by replenishment with cells saved from earlier in your life?"

What the team of scientists on the study now believe is it may be possible to rejuvenate the body later in  life with re-injections of stem cells saved from birth or early life.

"If I took a sample now and gave it back to myself when I'm older, I would have long telomeres again -although it might only be possible with blood, not other tissue," Holstege added.

Telomeres are the protective tips on chromosomes that burn down each time a cell divides. During the course of life, the number of active stem cells shrinks, and their telomeres shorten to the point at which they die as part of the process known as stem-cell exhaustion.

The research in this study may also be used to help protect against Alzheimer's disease and possibly pave the way for earlier detection of cancer.