1
|
Lira Dos Santos EJ, Salmon CR, Chavez MB, de Almeida AB, Tan MH, Chu EY, Sallum EA, Casati MZ, Ruiz KGS, Kantovitz KR, Foster BL, Nociti Júnior FH. Cementocyte alterations associated with experimentally induced cellular cementum apposition in hyp mice. J Periodontol 2021; 92:116-127. [PMID: 34003518 DOI: 10.1002/jper.21-0119] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/10/2021] [Accepted: 05/10/2021] [Indexed: 02/05/2023]
Abstract
BACKGROUND Cellular cementum, a mineralized tissue covering apical tooth roots, grows by apposition to maintain the tooth in its occlusal position. We hypothesized that resident cementocytes would show morphological changes in response to cementum apposition, possibly implicating a role in cementum biology. METHODS Mandibular first molars were induced to super-erupt (EIA) by extraction of maxillary molars, promoting rapid new cementum formation. Tissue and cell responses were analyzed at 6 and/or 21 days post-procedure (dpp). RESULTS High-resolution micro-computed tomography (micro-CT) and confocal laser scanning microscopy showed increased cellular cementum by 21 dpp. Transmission electron microscopy (TEM) revealed that cementocytes under EIA were 50% larger than control cells, supported by larger pore sizes detected by micro-CT. Cementocytes under EIA displayed ultrastructural changes consistent with increased activity, including increased cytoplasm and nuclear size. We applied EIA to Hyp mutant mice, where cementocytes have perilacunar hypomineralization defects, to test cell and tissue responses in an altered mechanoresponsive milieu. Hyp and WT molars displayed similar super-eruption, with Hyp molars exhibiting 28% increased cellular cementum area versus 22% in WT mice at 21 dpp. Compared to control, Hyp cementocytes featured well-defined, disperse euchromatin and a thick layer of peripherally condensed heterochromatin in nuclei, indicating cellular activity. Immunohistochemistry (IHC) for cementum markers revealed intense dentin matrix protein-1 expression and abnormal osteopontin deposition in Hyp mice. Both WT and Hyp cementocytes expressed gap junction protein, connexin 43. CONCLUSION This study provides new insights into the EIA model and cementocyte activity in association with new cementum formation.
Collapse
Affiliation(s)
- Elis J Lira Dos Santos
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas, São Paulo, Brazil
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH
| | - Cristiane R Salmon
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas, São Paulo, Brazil
- Faculty of Dentistry, N. Sra. do Patrocínio University Center, Itu, São Paulo, Brazil
| | - Michael B Chavez
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH
| | - Amanda B de Almeida
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas, São Paulo, Brazil
| | - Michelle H Tan
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH
| | - Emily Y Chu
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD
| | - Enilson A Sallum
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas, São Paulo, Brazil
| | - Marcio Z Casati
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas, São Paulo, Brazil
| | - Karina G S Ruiz
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas, São Paulo, Brazil
| | - Kamila R Kantovitz
- Department of Dental Materials, São Leopoldo Mandic Research Center, Campinas, São Paulo, Brazil
| | - Brian L Foster
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH
| | - Francisco H Nociti Júnior
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas, São Paulo, Brazil
- São Leopoldo Mandic Research Center, Campinas, São Paulo, Brazil
| |
Collapse
|
2
|
Abstract
Cementum is a mineralized tissue covering the tooth root that functions in tooth attachment and posteruptive adjustment of tooth position. During formation of the apically located cellular cementum, some cementoblasts become embedded in the cementoid matrix and become cementocytes. As apparently terminally differentiated cells embedded in a mineralized extracellular matrix, cementocytes are part of a select group of specialized cells, also including osteocytes, hypertrophic chondrocytes, and odontoblasts. The differentiation and potential function(s) of cementocytes are virtually unknown, and the question may be posed whether the cementocyte is a dynamic actor in cementum in comparable fashion with the osteocyte in the skeleton, responding to changing tooth functions and endocrine signals and actively directing local cementum metabolism. This review summarizes the literature with regard to cementocytes, comparing them to their closest "cousins," the osteocytes, where insights gained from osteocyte studies serve to inform the critical examination of cementocytes. The review identifies important unanswered questions about these cells regarding their origins, differentiation, morphology and lacuno-canalicular system, selective markers, and potential functions.
Collapse
Affiliation(s)
- N Zhao
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA Department of Orthodontics, Shanghai Key Laboratory of Stomatology, Shanghai No. 9 Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - B L Foster
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - L F Bonewald
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| |
Collapse
|
3
|
Zhao N, Nociti FH, Duan P, Prideaux M, Zhao H, Foster BL, Somerman MJ, Bonewald LF. Isolation and Functional Analysis of an Immortalized Murine Cementocyte Cell Line, IDG-CM6. J Bone Miner Res 2016; 31:430-442. [PMID: 26274352 PMCID: PMC4827449 DOI: 10.1002/jbmr.2690] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 08/08/2015] [Accepted: 08/12/2015] [Indexed: 12/30/2022]
Abstract
The dental cementum covering the tooth root is similar to bone in several respects but remains poorly understood in terms of development and differentiation of cementoblasts, as well as the potential function(s) of cementocytes residing in the cellular cementum. It is not known if the cementocyte is a dynamic actor in cementum metabolism, comparable to the osteocyte in the bone. Cementocytes exhibit irregular spacing and lacunar shape, with fewer canalicular connections compared with osteocytes. Immunohistochemistry and quantitative PCR (qPCR) revealed that the in vivo expression profile of cementocytes paralleled that of osteocytes, including expression of dentin matrix protein 1 (Dmp1/DMP1), Sost/sclerostin, E11/gp38/podoplanin, Tnfrsf11b (osteoprotegerin [OPG]), and Tnfsf11 (receptor activator of NF-κB ligand [RANKL]). We used the Immortomouse(+/-); Dmp1-GFP(+/-) mice to isolate cementocytes as Dmp1-expressing cells followed by immortalization using the interferon (IFN)-γ-inducible promoter driving expression of a thermolabile large T antigen to create the first immortalized line of cementocytes, IDG-CM6. This cell line reproduced the expression profile of cementocytes observed in vivo, including alkaline phosphatase activity and mineralization. IDG-CM6 cells expressed higher levels of Tnfrsf11b and lower levels of Tnfsf11 compared with IDG-SW3 osteocytes, and under fluid flow shear stress, IDG-CM6 cells significantly increased OPG while decreasing RANKL, leading to a significantly increased OPG/RANKL ratio, which would inhibit osteoclast activation. These studies indicate similarities yet potentially important differences in the function of cementocytes compared with osteocytes and support cementocytes as mechanically responsive cells.
Collapse
Affiliation(s)
- Ning Zhao
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA.,Department of Orthodontics, Shanghai Key Laboratory of Stomatology, Shanghai No. 9 Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Francisco H Nociti
- Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA.,Department of Prosthodontics and Periodontics, Division of Periodontics, School of Dentistry at Piracicaba, Piracicaba, Sao Paulo, Brazil
| | - Peipei Duan
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA.,Department of Orthodontics, State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, Chengdu, China
| | - Matthew Prideaux
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA.,Bone Cell Biology Group, Centre for Orthopaedic & Trauma Research, University of Adelaide, Adelaide, Australia
| | - Hong Zhao
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Brian L Foster
- Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA.,Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Martha J Somerman
- Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Lynda F Bonewald
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| |
Collapse
|