Telomerase protects adult rodent olfactory ensheathing glia from early senescence.

Adult olfactory bulb ensheathing glia (OB-OEG) promote the repair of acute, subacute, and chronic spinal cord injuries and autologous transplantation is a feasible approach. There are interspecies differences between adult rodent and primate OB-OEG related to their longevity in culture. Whereas primate OB-OEG exhibit a relatively long life span, under the same culture conditions rodent OB-OEG divide just three to four times, are sensitive to oxidative stress and become senescent after the third week in vitro. Telomerase is a "physiological key regulator" of the life span of normal somatic cells and also has extratelomeric functions such as increased resistance to oxidative stress. To elucidate whether telomerase has a role in the senescence of rodent OB-OEG, we have introduced the catalytic subunit of telomerase mTERT into cultures of these cells by retroviral infection. Native and modified adult rat OB-OEG behaved as telomerase-competent cells as they divided while expressing mTERT but entered senescence once the gene switched off. After ectopic expression of mTERT, OB-OEG resumed division at a nonsenescent rate, expressed p75 and other OEG markers, and exhibited the morphology of nonsenescent OB-OEG. The nonsenescent period of mTERT-OEG lasted 9weeks and then ectopic mTERT switched off and cells entered senescence again. Our results suggest a role of telomerase in early senescence of adult rodent OB-OEG cultures and a protection from oxidative damage. This article is part of a Special Issue entitled: Understanding olfactory ensheathing glia and their prospect for nervous system repair.