Immortalization of cementoblast progenitor cells with Bmi-1 and TERT.
A cementoblast progenitor cell line designated BCPb8 was successfully isolated from dental follicle cells immortalized with Bmi-1 and hTERT. BCPb8 showed the potential to differentiate into cementoblasts on implantation into immunodeficient mice. BCPb8 was confirmed to be the first established cementoblast progenitor cell line and will provide a useful model for investigating cementogenesis.


BACKGROUND
The dental follicle is the mesenchymal tissue surrounding the developing tooth germ. During tooth root development, progenitor cells present in the dental follicle are believed to play a central role in the formation of periodontal components (cementum, periodontal ligament, and alveolar bone). However, little more is known about the biology of these progenitors. Previously, we observed that cultured bovine dental follicle cells (BDFCs) contained putative cementoblast progenitors. To further analyze the biology of these cells, we attempted to isolate cementoblast progenitors from immortalized BDFC through expression of the polycomb group protein, Bmi-1, and human telomerase reverse transcriptase (hTERT).


METHODS
BDFCs were transduced with replication-deficient retroviruses carrying human Bmi-1(LXSN-Bmi-1), and hTERT (LXSH-hTERT) for immortalization. Single cell clones were established from immortalized BDFC, and differentiation into cementoblasts was assessed by implantation into immunodeficient mice.


CONCLUSIONS
BDFCs expressing Bmi-1 and hTERT showed an extended life span-90 population doublings more than normal BDFCs-and still contained cells with the potential to differentiate into cementoblasts on implantation into immunodeficient mice. From these cells, we established a clonal cell line, designated BCPb8, which formed cementum-like tissue that was reactive to the anti-cementum-specific monoclonal antibody 3G9 and expressed mRNA for bone sialoprotein, osteocalcin, osteopontin, and type I collagen on implantation. Thus, by using Bmi-1 and hTERT, we succeeded in immortalizing cementoblast progenitor cells from BDFC without affecting differentiation potential. The BCPb8 cell line is the first immortalized clonal cell line of cementoblast progenitors and could be a useful tool not only to study cementogenesis but also to develop regeneration therapy for patients with periodontitis.
Saito
Masahiro
M
Department of Operative Dentistry and Endodontics, Kanagawa Dental College, Yokosuka, Japan.
Handa
Keisuke
K
Kiyono
Tohru
T
Hattori
Shintaro
S
Yokoi
Takamasa
T
Tsubakimoto
Takanori
T
Harada
Hidemitsu
H
Noguchi
Toshihide
T
Toyoda
Minoru
M
Sato
Sadao
S
Teranaka
Toshio
T
D000818:Animals; D002417:Cattle; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002461:Cell Line, Transformed; D025021:Cementogenesis; D004268:DNA-Binding Proteins; D003739:Dental Cementum / Q000166:cytology* / Q000378:metabolism; D015870:Gene Expression; D005822:Genetic Vectors / Q000235:genetics; D058574:Integrin-Binding Sialoprotein; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D053495:Osteopontin; D063150:Polycomb Repressive Complex 1; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012190:Retroviridae / Q000235:genetics; D012795:Sialoglycoproteins / Q000235:genetics / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*
C069077:BMI1 protein, human; D004268:DNA-Binding Proteins; C546871:IBSP protein, human; C546872:Ibsp protein, mouse; D058574:Integrin-Binding Sialoprotein; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; D053495:Osteopontin; D063150:Polycomb Repressive Complex 1; C509186:TERT protein, human; D019098:Telomerase