A Novel Magnetic Manipulation Promotes Directional Growth of Periodontal Ligament Stem Cells

Periodontium is the rally of soft and hard tissues, which will be devastated continuously by the compromise of periodontitis. Current periodontal therapeutic methods cannot effectively reconstruct periodontal ligament (PDL), which is oriented at an angle with tooth root and combined hard tissues to form cementum-PDL-alveolar bone complex. Hence, it is urgent to find new techniques for PDL reconstruction to achieve functional regeneration of periodontium. Herein, we developed a novel method to manipulate the distribution and growth of periodontal ligament stem cells (PDLSCs) by utilizing highly paralleled static magnetic field (SMF) and magnetic nanoparticles (MNPs). PDLSCs were incubated with MNPs in vitro to label with them. Meanwhile, CCK8 and live/dead cell staining assay were used to detect the impact of SMF and MNPs on cell viability. The directional migration and growth of PDLSCs were visualized under microscope. Furthermore, real-time quantitative PCR and western blot were utilized to calculate the expression level of PDL-related genes. The results showed that PDLSCs could rapidly take up MNPs without compromising cell proliferation and viability, consequently endowed with the ability to respond via magnetic force. The cell migration analysis indicated that PDLSCs could move along the magnetic induction line, testifying that SMF exerted forces on PDLSCs that labeled with MNPs. It was demonstrated that collective application of SMF and MNPs not only induced PDLSCs organized and grew directionally, but also initiated elongation of cells and nucleus. Furthermore, the morphological alteration of the nucleus could also effectively enhance the gene and protein expression of Collagen Iα2, Collagen III, and Periostin, suggesting the capability of PDLSCs to differentiate into PDL. In conclusion, this study exhibits a new approach for directional reconstruction of PDL to obtain physiological and functional regeneration of periodontium. The Clinical Trial Registration number: WCHSIRB-D-2022-458.