title: Effects of Recombinant Overexpression of Bcl2 on the Proliferation, Apoptosis, and Osteogenic/Odontogenic Differentiation Potential of Dental Pulp Stem Cells.
abstract: BACKGROUND
  The therapeutic usefulness of dental pulp stem cells (DPSCs) is severely limited by low survivability upon transplantation in situ because of the presence of various proapoptotic factors within damaged/diseased tissues (ie, hypoxia and inflammation). One strategy to enhance the survivability of grafted DPSCs could be recombinant overexpression of antiapoptotic genes, such as the B-cell lymphoma 2 gene (Bcl2).
  
  
  METHODS
  DPSCs were transfected with the Bcl2 and/or GFP gene. Cell density and mitotic activity of transfected DPSCs within in vitro culture were evaluated with the water soluble tetrazolium salt-8 (WST-8) and bromodeoxyuridine assay, respectively, whereas apoptosis was evaluated through the detection of cytoplasmic histone-associated DNA fragments. The osteogenic/odontogenic differentiation potential of these cells was evaluated with quantitative real-time polymerase chain reaction, alkaline phosphatase, and alizarin red staining.
  
  
  RESULTS
  Bcl2-transfected DPSCs exhibited consistently higher cell densities than the GFP-transfected control within in vitro culture, and this was not because of the higher mitotic rate but was instead attributed to enhanced cell survivability because of the inhibition of apoptosis by Bcl2. Recombinant overexpression of Bcl2 inhibited the osteogenic/odontogenic potential of DPSCs, as indicated by lower levels of alkaline phosphatase activity and mineralized calcium deposition, together with the down-regulated expression of several key osteogenic/odontogenic gene markers including collagen I, osteocalcin, dentin matrix protein-1, bone sialoprotein, and alkaline phosphatase.
  
  
  CONCLUSIONS
  The results place a "caveat" or limitation on the use of recombinant Bcl2 overexpression as a therapeutic strategy for improving the survivability of grafted DPSCs in that the osteogenic/odontogenic potential of these cells may be compromised despite enhanced survival within the host.
authors.affiliation: Comprehensive Dental Care, Endodontics, Faculty of Dentistry, The University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Boon Chin
authors.initials: BC
authors.lastname: Heng
authors.affiliation: Comprehensive Dental Care, Endodontics, Faculty of Dentistry, The University of Hong Kong, Pokfulam, Hong Kong; School of Stomatology, Shandong University, Jinan, Shandong, China; Shandong Provincial Key Laboratory of Oral Tissue Regeneration, Shandong University, Jinan, Shandong, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Ye
authors.affiliation: Comprehensive Dental Care, Endodontics, Faculty of Dentistry, The University of Hong Kong, Pokfulam, Hong Kong; Shenzhen Institute of Research and Innovation, The University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Comprehensive Dental Care, Endodontics, Faculty of Dentistry, The University of Hong Kong, Pokfulam, Hong Kong; Shenzhen Institute of Research and Innovation, The University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Waruna Lakmal
authors.initials: WL
authors.lastname: Dissanayaka
authors.affiliation: Comprehensive Dental Care, Endodontics, Faculty of Dentistry, The University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Gary Shun Pan
authors.initials: GS
authors.lastname: Cheung
authors.affiliation: Comprehensive Dental Care, Endodontics, Faculty of Dentistry, The University of Hong Kong, Pokfulam, Hong Kong; Shenzhen Institute of Research and Innovation, The University of Hong Kong, Pokfulam, Hong Kong. Electronic address: zhangcf@hku.hk.
authors.forename: Chengfei
authors.initials: C
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D017209:Apoptosis / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology; D002478:Cells, Cultured; D003782:Dental Pulp / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D009805:Odontogenesis / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D055815:Young Adult
chemical_list: C000595707:BCL2 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins
keywords: Apoptosis; Bcl2; dental pulp stem cells; osteogenic differentiation; proliferation