Transient increase in telomerase activity of proliferating fibroblasts and endothelial cells in granulation tissue of the human skin.

Although granulation tissue formation is an important step for second-intention wound healing, the molecular events underlying this process are still poorly understood. To investigate the role of telomerase in the formation of granulation tissue, we measured the activity of this enzyme and determined the expression and localization of human telomerase reverse transcriptase mRNA using human skin samples. Telomerase activity in the tip of the granulation tissue where fibroblasts actively proliferate was detected at a level 5.6 +/- 1.5 times higher than that at the edge of the tissue when using a polymerase chain reaction-based telomeric repeat amplification protocol assay coupled with enzyme-linked immunosorbent assay. This, together with the findings from semiquantitative reverse transcriptase-polymerase chain reaction and in situ hybridization of human telomerase reverse transcriptase, revealed that proliferating cell nuclear antigen-positive fibroblasts and endothelial cells in the progressing granulation tissue showed de novo activation of telomerase with high human telomerase reverse transcriptase mRNA expression. This condition may be a prolongation of cellular replicative capacity taking advantage of the positive regulatory dynamics of cell growth. We conclude that the regulation of telomerase activity may play an important role in granulation tissue formation in wound healing.