A telomere is a region of repetitive nucleotide sequences associated with specialized proteins located at the ends of linear eukaryotic chromosomes to protect the chromosomes from progressive degradation and ensure its integrity. During cell division, telomeres will shorten gradually in human somatic cells, which limits the number of times they can divide. Therefore, telomeres are considered to be closely related to cell aging. Telomerase will be activated during cell division to synthesize telomere DNA for compensating the loss of telomeres.