Effect of fibrillin-2 on differentiation into periodontal ligament stem cell-like cells derived from human-induced pluripotent stem cells

Periodontal tissue regeneration is important for preserving teeth. Periodontal ligament stem cells (PDLSCs) are useful in periodontal tissue regeneration, however tooth extraction is required to obtain these cells. Therefore, we focused on induced pluripotent stem (iPS) cells and established a method to obtain PDLSC-like cells from iPS cells. Specifically, we first differentiated iPS cells into neural crest-like cells (iNCs). Next, we obtained PDLSC-like cells (iPDLSCs) by culturing iNCs on extracellular matrix (ECM) derived from human primary periodontal ligament cells (HPDLCs). This differentiation method suggested that ECM derived from HPDLCs is important for iPDLSC differentiation. Thus, we aimed to identify the PDLSC-inducing factor present in HPDLC-derived ECM in this study. We first performed comprehensive analyses of HPDLC genes and identified fibrillin-2 (FBN2), an ECM-related factor. Furthermore, to clarify the effect of FBN2 on iPDLSC differentiation, we cultured iNCs using ECM derived from HPDLCs with FBN2 knocked down. As a result, expression of PDL-related markers was reduced in iNCs cultured on ECM derived from HPDLCs transfected with FBN2 siRNA (iNC-siFBN2) compared with iPDLSCs. Furthermore, expression of CD105 (a mesenchymal stem cell marker), proliferation ability, and multipotency of iNC-siFBN2 were lower compared with iPDLSCs. Next, we cultured iNCs on FBN2 recombinant protein, however expression of PDL-related markers did not increase compared with iPDLSC. The present results suggested the critical involvement of FBN2 in inducing iPDLSCs from iNCs whereas it does not promote per se. Therefore, we need to elucidate the entire HPDLC-ECMs, responsible for iPDLSCs induction.