this roadblock is known as the hayflick limit. on top of that, as a person's cells divide, they also accumulate damage and release toxic waste side products. as these toxins build up over time, the affected cells gradually lose their ability to function. thiss the aging process at cellular level. - that's the important thing about living critters, is we do have things break down, but we also have the ability to repair damage. - re. - in principlethe goal would be to boost the ability to repair the damage. - to capitalize on this process of regeneration, lenny and his team targeted a gene in live roundworms called sir-2. sir-2 genes create proteins called sirtuins. these sirtuins coordinate the cells response to stress, including repairing dna damage, which can slow the aging process. oh my god. - [lenny] they're alive, they should be moving. - yeah, oh yeah, they're moving around. they look like little threads. - so we first looked at the round worms and we found that, yes, the worms sir-2 gene was involved in aging. and so by ext