Comparison of characteristics of periodontal ligament cells obtained from outgrowth and enzyme-digested culture methods

Objective: Periodontal ligament (PDL) cells have an important role in periodontal regeneration. The unique characteristics of PDL cells, mainly outgrown cells derived from PDL tissue, have been investigated. Recently, mesenchymal stem cells have been obtained from PDL tissue using enzyme digestion. The differences in properties of those PDL cells cultured by the two methods (outgrowth and enzyme digestion) are unclear. The objective of this study was to investigate the characteristics of PDL cells obtained by these methods. Methods: PDL cells from extracted tooth were cultured using outgrowth and enzyme digest methods. Cell proliferation, colony-forming activity and differentiation capacity to osteoblast, adipocyte and chondrocyte were compared. Gene expressions for PDL cells, mesenchymal stem cells and fibroblasts were also investigated by reverse transcription polymerase chain reaction. Procollagen type I c-peptide (PIP) production was measured using an enzyme-linked immunosorbent assay (ELISA) kit. Results: PDL cells cultured by enzyme digest methods showed a higher proliferation rate, colony-forming activity and differentiation capacity into osteoblast, adipocyte and chondrocyte than those in PDL cells by outgrowth method. CD166, one of the mesenchymal stem cell markers, was slightly higher in enzyme-digested PDL than in outgrowth PDL, whilst gene expressions for type 1 collagen alpha 1 and type 3 collagen were higher in outgrown PDL cells. Moreover, outgrowth PDL exhibited higher PIP production than enzyme-digested PDL cells. Conclusion: PDL cells obtained by outgrowth and enzyme digestion showed different characteristics. The enzyme digestion method yielded cells with higher proliferation rate and mesenchymal stem cell-like properties, whereas cells with fibroblast-like properties were collected in the outgrowth method. PDL cell properties by different culture methods may provide information for inventing new therapeutic uses of PDL cells. (C) 2010 Elsevier Ltd. All rights reserved.