A lot of scintists believe that one of main reasons for cellular senecsence is oxidative stress. Active forms of oxigen, like hydroxyl ion or single oxygen, could appear in the cell during mitochondria's work and as side product of a lot of other cellular processes. If you want to read more, just read a book....
There are also organels in cell that can utilize active forms of oxygen. These organels are called peroxisomes, they containe enzymes able to convert active forms of oxigen into safe O2 and water. Scientist from University of Basel, Switzerland managed to create artificial peroxisomes,a polymeric capsules with channels which allow chemicals and compounds to get in and out of the peroxisome.
Artifical peroxisomes successfuly helped to utilize active forms of oxygen and they could effectivly prevent cellular senescense.
Aiding Nature’s Organelles: Artificial Peroxisomes Play Their Role
Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
Nano Lett., 2013, 13 (6), pp 2875–2883, DOI: 10.1021/nl401215n