Human periodontal ligament fibroblast(hPDLF) is very important to cure periodontal tissue because it can be diverged into various cells. This study examined the expression of MMP-1, TIMP-1, periodontal ligament specific PDLs22, Type I collagen, Fibronectin, TIMP-2, telomerase mRNA in a replicative senescence of hPDLF.

The periodontal ligament tissue was obtained from periodontally healthy and non-carious human teeth extracted for orthodontic reasons at the Chosun University Hospital of Dentistry with the donors' informed consent. The hPDLF cells were cultured in a medium containing Dulbecco's modified Eagle medium(DMEM, Gibco BRL, USA) supplemented with 10% fetal bovine serum(FBS, Gibco BRL, USA) at 37C in humidified air with 5% CO₂. For the reverse transcription-polymerase chain reaction(RT-PCR) analysis, the total RNA of the 2, 4, 8, 16, 18, and 21 passage cells was extracted using a Trizol Reagent(Invitrogen, USA) in replicative hPDL cells. Two passage cells, i.e. young cells, served as the control, and beta-actin served as the internal control for RT-PCR.

The results of this study about cell morphology and gene expression according to aging of hPDLF using RT-PCR method are as follows:

1. The size of hPDLF was increased with aging and it was showed that the hPDLF was dying in the final passage.

2. PDLs22 mRNA was expressed in young hPDLF of the two, four, and six passage.

3. TIMP-1 mRNA was expressed in young hPDLF of the two and four passage.

4. There was a tendency that MMP-1 mRNA was weakly expressed over eighteen.

5. Type 1 collagen mRNA was expressed in almost all passages, but it was not expressed in the final passage.

6. Fibronectin mRNA was observed in all passages and it was weakly expressed in the final passage.

7. TIMP-2 and telomerase mRNA were not expressed in this study.

Based on above results, it was observed that PDLs22, Type 1 collagen, Fibronectin, MMP-1. and TIMP-1 mRNA in hPDLF were expressed differently with aging. The study using the hPDLF that is collected from healthy patients and periodontitis patients needs in further study.