is it possible injecting pure telomerase would work or would it not be able to get inside the cells?
I thought adeno associated virus would be used if it were ever done? But would you not be able to use that on a large quantity of cells?
enzymes cannot get into the cell especially not the nucleus where your genes are. The reason adenovirus is unfavorable is precisely because you mentioned telomerase as in the gene will only be used when the cell divides. Adenoviruses' genes cannot be passed onto the daughter cells because their dna is never integrated into the host unlike retroviruses that do integrate their genes into the host.
Biolistic particle delivery system? You coat a heavy metal (usually gold) with DNA, which is then shot through tissues. While the heavy metal passes through the cells the DNA gets stripped and stays behind in the cells. No, for obvious reasons.