title: Immunohistochemical and histochemical analysis of newly formed tissues in root canal space transplanted with dental pulp stem cells plus platelet-rich plasma.
abstract: BACKGROUND
  Tissue regeneration in root canals after pulpectomy can be achieved by transplantation of autologous dental pulp stem cells and/or platelet-rich plasma. However, the identity of the newly formed tissue in the pulp space has been only examined by histologic analysis. This study aimed to apply immunohistochemistry and histochemistry to detect specific markers in the newly generated tissues after root canal regenerative treatment.
  
  
  METHODS
  In our previous study, 32 root canals in 4 mature dogs were treated with a pulp regeneration procedure after pulpectomy using either blood clot, transplantation of dental pulp stem cells, platelet-rich plasma, or a combination of cells and plasma. In the present study, the tissues were examined for the expression of periostin to detect periodontal ligament tissue, nestin and dentin sialoprotein for odontoblasts, and bone sialoprotein and osteocalcin for bone tissues. Samples were also stained for tartrate-resistant acid phosphatase (TRAP) as a marker for osteoclastic lineages.
  
  
  RESULTS
  Continuous periostin-positive tissue was observed extending from the periodontal ligament into the inner canal surface in which the mineral islands were surrounded by weak periostin staining. There was also positive staining for TRAP, bone sialoprotein, and osteocalcin in the canal space, suggesting the presence of bone tissue. A layer of mineralized tissue along the inner surface of the root canal was negative for TRAP, suggesting the tissue likely to be cementum. In all samples, no nestin-positive reaction was observed, whereas dentin sialoprotein was detected in PDL, dentinal tubules, and intracanal fibrous tissues. There was no difference between any of the 4 groups.
  
  
  CONCLUSIONS
  The tissues formed in the dog mature root canals after regenerative endodontic procedures are not pulp tissues but mainly periodontal tissues.
authors.affiliation: VIP Dental Service, School and Hospital of Stomatology, Peking University, Beijing, China; The University of Hong Kong, Shenzhen Institute of Research and Innovation, Hong Kong, China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Zhu
authors.affiliation: School and Hospital of Stomatology, Peking University, Beijing, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: The University of Hong Kong, Shenzhen Institute of Research and Innovation, Hong Kong, China; Comprehensive Dental Care, The University of Hong Kong, Hong Kong, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Bioscience Research, University of Tennessee Health Science Center, College of Dentistry, Memphis, Tennessee.
authors.forename: George T-J
authors.initials: GT
authors.lastname: Huang
authors.affiliation: The University of Hong Kong, Shenzhen Institute of Research and Innovation, Hong Kong, China; Comprehensive Dental Care, The University of Hong Kong, Hong Kong, China. Electronic address: zhangcf@hku.hk.
authors.forename: Chengfei
authors.initials: C
authors.lastname: Zhang
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000539:Alveolar Process / Q000033:anatomy & histology; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D001777:Blood Coagulation / Q000502:physiology; D002113:Calcification, Physiologic / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000032:analysis; D003739:Dental Cementum / Q000033:anatomy & histology; D003782:Dental Pulp / Q000166:cytology*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D003804:Dentin / Q000648:ultrastructure; D004285:Dogs; D016326:Extracellular Matrix Proteins / Q000032:analysis; D006651:Histocytochemistry; D007150:Immunohistochemistry; D058574:Integrin-Binding Sialoprotein / Q000032:analysis; D007527:Isoenzymes / Q000032:analysis; D064231:Nestin / Q000032:analysis; D009804:Odontoblasts / Q000166:cytology; D015675:Osteocalcin / Q000032:analysis; D010010:Osteoclasts / Q000166:cytology; D010513:Periodontal Ligament / Q000033:anatomy & histology; D010750:Phosphoproteins / Q000032:analysis; D053657:Platelet-Rich Plasma / Q000502:physiology*; D011670:Pulpectomy / Q000379:methods; D012038:Regeneration / Q000502:physiology; D012795:Sialoglycoproteins / Q000032:analysis; D033581:Stem Cell Transplantation / Q000379:methods*; D000071681:Tartrate-Resistant Acid Phosphatase; D000099311:Dentin Sialophosphoprotein
chemical_list: D000135:Acid Phosphatase; D015415:Biomarkers; D015815:Cell Adhesion Molecules; D016326:Extracellular Matrix Proteins; D058574:Integrin-Binding Sialoprotein; D007527:Isoenzymes; D064231:Nestin; D015675:Osteocalcin; D010750:Phosphoproteins; D012795:Sialoglycoproteins; D000071681:Tartrate-Resistant Acid Phosphatase; D000099311:Dentin Sialophosphoprotein
keywords: Dental pulp stem cells; histochemical analysis; immunohistochemical examination; platelet-rich plasma; regeneration