title: Differentiation and characteristics of undifferentiated mesenchymal stem cells originating from adult premolar periodontal ligaments.
abstract: OBJECTIVE
  The purpose of this study was to investigate the isolation and characterization of multipotent human periodontal ligament (PDL) stem cells and to assess their ability to differentiate into bone, cartilage, and adipose tissue.
  
  
  METHODS
  PDL stem cells were isolated from 7 extracted human premolar teeth. Human PDL cells were expanded in culture, stained using anti-CD29, -CD34, -CD44, and -STRO-1 antibodies, and sorted by fluorescent activated cell sorting (FACS). Gingival fibroblasts (GFs) served as a positive control. PDL stem cells and GFs were cultured using standard conditions conducive for osteogenic, chondrogenic, or adipogenic differentiation.
  
  
  RESULTS
  An average of 152.8 ± 27.6 colony-forming units was present at day 7 in cultures of PDL stem cells. At day 4, PDL stem cells exhibited a significant increase in proliferation (p < 0.05), reaching nearly double the proliferation rate of GFs. About 5.6 ± 4.5% of cells in human PDL tissues were strongly STRO-1-positive. In osteogenic cultures, calcium nodules were observed by day 21 in PDL stem cells, which showed more intense calcium staining than GF cultures. In adipogenic cultures, both cell populations showed positive Oil Red O staining by day 21. Additionally, in chondrogenic cultures, PDL stem cells expressed collagen type II by day 21.
  
  
  CONCLUSIONS
  The PDL contains multipotent stem cells that have the potential to differentiate into osteoblasts, chondrocytes, and adipocytes. This adult PDL stem cell population can be utilized as potential sources of PDL in tissue engineering applications.
authors: Department of Orthodontics, School of Dentistry, Pusan National University, Yangsan, Korea.
authors: Seong Sik
authors: SS
authors: Kim
authors: Dae-Woo
authors: DW
authors: Kwon
authors: Insook
authors: I
authors: Im
authors: Yong-Deok
authors: YD
authors: Kim
authors: Dae-Seok
authors: DS
authors: Hwang
authors: L Shannon
authors: LS
authors: Holliday
authors: Richard E
authors: RE
authors: Donatelli
authors: Woo-Sung
authors: WS
authors: Son
authors: Eun-Sook
authors: ES
authors: Jun
keywords: Bone biology; Histochemistry; Periodontics