title: Directing adult human periodontal ligament-derived stem cells to retinal fate.
abstract: OBJECTIVE
  To investigate the retinal fate competence of human postnatal periodontal ligament (PDL)-derived stem cells (PDLSC) through a directed differentiation mimicking mammalian retinogenesis.
  
  
  METHODS
  Human teeth were collected from healthy subjects younger than 35 years old. Primary PDLSC were isolated by collagenase digestion and cultivated. PDLSC at passage 3 were cultured in the induction media containing Noggin (antagonist of bone morphogenic protein) and Dkk-1 (antagonist of Wnt/β-catenin signaling). Gene expression of neural crest cells, retinal progenitors, and retinal neurons, including photoreceptors, was revealed by RNA analyses, immunofluorescence, and flow cytometry. The neuronal-like property of differentiated cells in response to excitatory glutamate was examined by fluo-4-acetoxymethyl calcium imaging assay.
  
  
  RESULTS
  Primary human PDLSC stably expressed marker genes for neural crest (Notch1, BMP2, Slug, Snail, nestin, and Tuj1), mesenchymal stem cell (CD44, CD90, and vimentin), and embryonic stem cell (c-Myc, Klf4, Nanog, and SSEA4). Under low attachment culture, PDLSC generated neurospheres expressing nestin, p75/NGFR, Pax6, and Tuj1 (markers of neural progenitors). When neurospheres were plated on Matrigel-coated surface, they exhibited rosette-like outgrowth. They expressed eye field transcription factors (Pax6, Rx, Lhx, Otx2). By flow cytometry, 94% of cells were Pax6(nuclear)Rx(+), indicative of retinal progenitors. At prolonged induction, they expressed photoreceptor markers (Nrl, rhodopsin and its kinase) and showed significant responsiveness to excitatory glutamate.
  
  
  CONCLUSIONS
  Primary human PDLSC could be directed to retinal progenitors with competence for photoreceptor differentiation. Human neural crest-derived PDL is readily accessible and can be an ample autologous source of undifferentiated cells for retinal cell regeneration.
authors: Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
authors: Li
authors: L
authors: Huang
authors: Jiajian
authors: J
authors: Liang
authors: Yiqun
authors: Y
authors: Geng
authors: Wai-Ming
authors: WM
authors: Tsang
authors: Xiaowu
authors: X
authors: Yao
authors: Vishal
authors: V
authors: Jhanji
authors: Mingzhi
authors: M
authors: Zhang
authors: Herman S
authors: HS
authors: Cheung
authors: Chi Pui
authors: CP
authors: Pang
authors: Gary Hin-Fai
authors: GH
authors: Yam
mesh_terms: D000293:Adolescent; D000328:Adult; D053687:Adult Stem Cells / Q000166:cytology* / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D005136:Eye Proteins / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D000090062:Kruppel-Like Factor 4; D008297:Male; D055495:Neurogenesis / Q000502:physiology; D010513:Periodontal Ligament / Q000166:cytology*; D012160:Retina / Q000166:cytology* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D060449:Wnt Signaling Pathway / Q000502:physiology; D055815:Young Adult; D051176:beta Catenin / Q000037:antagonists & inhibitors / Q000378:metabolism; D000099176:Noggin Protein
chemical_list: D015415:Biomarkers; D002352:Carrier Proteins; D005136:Eye Proteins; D036341:Intercellular Signaling Peptides and Proteins; D000090062:Kruppel-Like Factor 4; D014157:Transcription Factors; D051176:beta Catenin; D000099176:Noggin Protein; C501126:DKK1 protein, human; C000715467:KLF4 protein, human
keywords: neurogenesis; periodontal ligament-derived stem cells; photoreceptors; retinal progenitors