Differences in periodontal ligament stem cells from maxilla and mandible

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ICE Krakow

ICE Krakow

ul. Marii Konopnickiej 17 30-302 Kraków


Malyaran, Hanna (Institute of Pathology, RWTH Aachen University)


Diseases of the periodontium start in general with the recession of the periodontal ligament (PDL) and leads to loosening of the tooth within the alveolar bone. The cementum and periodontal ligament play important roles in physiological tooth function. Therefore, cementum and periodontal ligament regeneration are critical for periodontal regenerative therapy. Decades of clinical experiences indicate, that velocity and efficiency of wound healing and bone remodeling in alveolar bone and PDL is in part dependent on the exact location of the wound. In the maxilla, the upper jaw, these processes are generally faster and more efficient than in the mandible, the lower jaw. Alveolar bone differs in composition, with 23% bone marrow and 46% lamellar bone in the upper jaw, and 16% bone marrow and 63% lamellar bone in the lower jaw, which may affect the recruitment of stem cells towards a wound. The PDL hosts endogenous stem cells, which were shown to differentiate towards osteoblast and cementoblasts in 1976. Since 2004, specific PDL cells can be isolated from extracted third molars, demonstrating self-renewal and differentiation capacity towards several mesodermal cell fates and therefor being referred to as stem cells. PDL cells in particular mesenchymal stem cells (MSC) have been extensively studied with respect to bone and tissue replacement strategies. The characterization of PDL cells from the upper and lower jaw compared to MSC will identify similarities and differences in cellular composition and unravel molecular pathways involved in differentially regulated wound healing in mandible and maxilla.

PDL cells were isolated from extracted third molars of young and healthy patients. Human tissue donations were received with informed consent. All cells were cultured with DMEM high glucose, 10% FCS and 50mg/l ascorbic acid in a 20% O2 and 5% CO2 humidified atmosphere at 37°C. Only patients with extracted teeth from both upper and lower jaws were considered for this study, to have a direct comparison between maxilla and mandible. PDL cells were compared to MSC isolated from the spongiosa of femoral heads. Surface characterization for stem cell (CD34-, CD45-, CD73+, CD90+ and 105+) and PDL specific marker were performed for both cell type. Proliferation rate and differentiation potential towards adipocytes, osteoblasts and chondrocytes of PDL cells from the upper and lower jaw was investigated. Wound healing assays were performed by scratch assay and migration of both cell types was evaluated by Boyden Chamber assays.

First results showed that PDL cells, isolated from upper and lower jaw, were positive for CD73, CD90 and CD105 but negative for CD34 and CD45. PDL cells from the upper jaw have a higher proliferation rate and differentiation potential when compared to PDL cells that were isolated from the lower jaw.

The wound healing and bone remodeling processes are more efficient in the upper jaw, than the lower jaw. However, the underlying regulatory mechanism is unclear. In this study, we attempted to identify regulatory genes involved in periodontal cell differentiation and clarify the differentiation mechanism for effective periodontal regenerative therapy.

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