Investigating a clonal human periodontal ligament progenitor/stem cell line in vitro and in vivo

Abstract

<jats:title>Abstract</jats:title><jats:p>The lifespan of the tooth is influenced by the periodontal ligament (PDL), a specialized connective tissue that connects the cementum with the tooth socket bone. Generation of a cell line from PDL progenitor/stem cells would allow development of tissue engineering‐based regenerative PDL therapy. However, little is known about the characteristics of PDL progenitor/stem cells because PDL tissue consists of a heterogeneous cell population and there are no pure PDL cell lines. Recently, we succeeded in immortalizing primary human PDL fibroblasts (HPLFs) by transfecting them with SV40 T‐antigen and <jats:italic>hTERT</jats:italic> (Cell Tissue Res 2006; 324: 117–125). In this study, we isolated three clonal cell lines from these immortalized cells (lines 1–4, 1–11, and 1–24) that express <jats:italic>RUNX‐2</jats:italic>, <jats:italic>Col I</jats:italic>, <jats:italic>ALP</jats:italic>, <jats:italic>OPN</jats:italic>, <jats:italic>OCN</jats:italic>, <jats:italic>RANKL</jats:italic>, <jats:italic>OPG</jats:italic>, <jats:italic>scleraxis</jats:italic>, <jats:italic>periostin</jats:italic>, <jats:italic>Col XII</jats:italic>, and <jats:italic>α‐SMA</jats:italic> mRNA. Immunocytochemical analysis demonstrated that CD146 was expressed in cell lines 1–4 and 1–11 and that STRO‐1 was expressed in lines 1–11 and 1–24. Lines 1–4 and 1–11 differentiated into osteoblastic cells and adipocytes when cultured in lineage‐specific differentiation media. Four weeks after transplanting cell line 1–11 into immunodeficient mice with β‐tricalcium phosphate (β‐TCP), the transplant produced cementum/bone‐like tissues around the β‐TCP. Eight weeks after transplantation, the 1–11 cell transplant formed PDL‐like structures on the surface of the β‐TCP. These data suggest that cell line 1–11 was derived from a progenitor/stem cell present in the PDL and should be very useful for studying the biology and regeneration of human periodontium. J. Cell. Physiol. 215: 743–749, 2008. © 2008 Wiley‐Liss, Inc.</jats:p>