Osteogenic Potential of Periodontal Dental Ligament Stem Cells stimulated with orthodontic forces

Objectives: Determinate if the orthodontic forces could improve the profile of PDLSCS and compare the response of PDLSC to form mineralized tissues using four optimized protocols for osteogenic differentiation.
Methods: PDLSC were collected from 25 healthy patients. Ten maxillary first premolars were loaded with mechanical force during 7 days before extraction for orthodontic purposes and 15 premolars were unloaded. Flow Cytometry was used for Cell characterization. Four protocols for osteogenic induction were applied for cultures of PDLSC and compared with negative and positive control cultures. Alizarin Red and Phosphatase Alkaline staining, and the expression of type-I collagen (Col1), runt-related transcription factor 2 (RUNX2), Osteoprotegerin (OPG) and Osteopontine (OP) quantify by qRT-PCR were employed to determine the osteogenic profile in each culture
Results: Flow Cytometry analysis revealed that PDLSC were a homogeneous population of CD90(+), CD105(+), STRO-1(+) CD34 (-) and CD45 (-) cells. The cells of periodontal ligament loading with orthodontic forces did not show statistical differences compared with not loading PDLSC. PDLSC showed osteogenic differentiation in mediums with ascorbate-2 phosphate and melatonin added. The group of PDLSC cultured with the standard protocol for osteogenesis plus ascorbate-2 phosphate showed in qRT-PCR analysis the best osteogenic profile, statistically significant increased expression of transcripts for RUNX2 (p=0,04) and the highest coloration for ARS and ALP
Conclusions: The results suggest that PDLSC have high potential for bone differentiation depending of the extrinsic factors of culture. It is necessary to perform future studies to understand if mechanical forces could improve the osteogenic profile of PDLSC.