The Stanford University Medical Center has announced that human cells stored and grown in their laboratory will be used for the first time in the United States to make vaccines. This marks a new era in the practice of vaccination in the country, according to Dr. Leonard Hayflick, a professor of medical microbiology at Stanford University School of Medicine. Dr. Hayflick, who passed away recently, was a pioneer in the development of a human cell strain in the late 1950s.
Hayflick's groundbreaking discovery in the early 1960s revealed that human cells can only divide a limited number of times before entering a phase called senescence and eventually dying. This phenomenon, known as the "Hayflick limit," challenged the previous belief held by many scientists that cells could divide indefinitely.
The Hayflick limit raised questions about how cells keep track of their division and age. The answer lies in telomeres, DNA sequences at the ends of chromosomes that shorten with each cell division. While the enzyme telomerase can add copies of DNA bases to restore telomere length, it is not a perfect solution, and cells eventually reach a point where they can no longer divide.
Despite the implications of the Hayflick limit on the human lifespan, advancements in technology and stem cell research offer possibilities for extending longevity. However, without replacing aging organs with new ones grown in a lab, humans are destined to wear out over time.
While Hayflick estimated the human lifespan limit to be 125 years, no individual has reached that age yet. His contributions to understanding cellular aging and the limitations of human cells have paved the way for further research in longevity and regenerative medicine.