The in vitro life-span of human periodontal ligament fibroblasts

The in vitro life-span of human periodontal ligament fibroblasts (PDLF) was studied on clones from periodontium of teeth extracted due to periodontiti s and dental caries (69 clones/192 individuals, aged 20-80 years) and from periodontium of teeth extracted for orthodontic reasons (23 clones/26 indiv iduals, aged 15-19 years). In the primary cultures the ratio of the number of cells expressing senescence-associated beta-galactosidase (SA-beta-Gal) to the total number of cells is significantly larger in PDLF (92 clones; 11 .1-1-4.9%) than in human gingival fibroblasts IGF) (10 clones; 0.5+/-10.1%) . The finite population doubling numbers (PD) of PDLF are not age-mutched a nd the mean PD of PDLF (7.1+/-2.9) is significantly smaller than GF (28.5+/ -3.2), IMR-90 (human lung fibroblasts, 5 clones; 44.3 +/- 2.2), and human o steoblasts (5 clones, 19.7 +/- 1.4). Comparing the ratio of the number of S A-beta-Gal positive cells to the total number of cells in primary culture, and the finite PD in PDLF cultures: 1) the ratio of 15-19 years old donor g roup is significantly smaller than in the other donor groups (20-29, 30-39, 40-49, 50-59 and 60-80 years old), and 2) there were no statistically sign ificant differences among the 20-29, 30-39, 40-49 and 5059 year old donor g roups, and the 30-39, 40-49, 5059 and 60-80 year old donor groups. These fi ndings suggest that the in vitro life-span of PDLF is shorter than other fi broblasts in the connective tissues and that PDLF may undergo senescence in adult clones without relation to donor's age, There may be more aged fibro blasts in periodontium than in other tissues, such as gingiva and lung. (C) 2000 Harcourt Publishers Ltd.