title: Effects of hypoxia on proliferation and osteogenic differentiation of periodontal ligament stem cells: an in vitro and in vivo study.
abstract: Changes in oxygen concentration may influence various innate characteristics of stem cells. The effects of varying oxygen concentration on human periodontal ligament stem cells (HPDLSCs) has not been explored, particularly under hypoxia-related conditions. First, HPDLSCs were cultured from the periodontium of human teeth using the outgrowth method. STRO-1 and CD146 expression of HPDLSCs was investigated by flow cytometry. To detect the multilineage differentiation capacities of HPDLSCs, osteogenic-like and adipogenic-like states were induced in cells. Next, HPDLSCs (passage 3) were exposed to normal oxygen (21% O2) or hypoxia (2% O2) conditions for 7 days and cell proliferation was evaluated. After culture in osteogenic medium for 7 days, osteoblastic differentiation was evaluated by semi-quantitative reverse transcription-polymerase chain reaction analysis to detect 3 osteoblastic markers: core-binding factor a 1/runt-related transcription factor 2, osteocalcin, and osteopontin. In addition, each cell group was incubated with a hydroxyapatite/tricalcium phosphate carrier and transplanted subcutaneously into the back of immunocompromised mice to investigate transplantation differences in vivo. HPDLSCs were isolated, cultured, and successfully identified. After exposure of HPDLSCs to hypoxia for 7 days, the proliferation rate was increased and showed higher osteogenic differentiation potential compared to control cells. After 12 weeks of transplantation, hypoxia-treated HPDLSCs differentiated into osteoblast-like cells that formed bone-like structures. These results suggest that oxygen concentrations affect various aspects of HPDLSC physiology and that hypoxia enhances osteogenic differentiation both in vivo and in vitro. Oxygen concentration may be a critical parameter for HPDLSCs during expansion and differentiation.
authors.affiliation: Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China doctorqingbin@hotmail.com.
authors.forename: Q B
authors.initials: QB
authors.lastname: Zhang
authors.affiliation: Department of Stomatology, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong Province, China.
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Zhang
authors.affiliation: Department of Stomatology, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong Province, China.
authors.forename: S L
authors.initials: SL
authors.lastname: Fang
authors.affiliation: Department of Pediatric Dentistry, Hospital of Stomatology, Guangzhou Medical University, Guangzhou, Guangdong Province, China.
authors.forename: Y R
authors.initials: YR
authors.lastname: Liu
authors.affiliation: Jiangsu Key Laboratory of Biological Cancer Therapy, Xuzhou Medical College, Xuzhou, China.
authors.forename: G
authors.initials: G
authors.lastname: Jiang
authors.affiliation: School of Medicine, University of California, San Diego, CA, USA.
authors.forename: K F
authors.initials: KF
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D015415:Biomarkers; D051929:CD146 Antigen / Q000378:metabolism; D018929:Cell Culture Techniques / Q000379:methods*; D002454:Cell Differentiation; D015687:Cell Hypoxia; D049109:Cell Proliferation; D002478:Cells, Cultured; D003470:Culture Media / Q000737:chemistry; D006801:Humans; D051379:Mice; D010012:Osteogenesis; D010513:Periodontal Ligament / Q000166:cytology* / Q000378:metabolism*; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D055815:Young Adult
chemical_list: D000954:Antigens, Surface; D015415:Biomarkers; D051929:CD146 Antigen; D003470:Culture Media; C497902:MCAM protein, human; C525591:STRO-1 antigen, human