title: A novel population of repair cells identified in the stroma of the human cornea.
abstract: The transmembrane protein CD133 is expressed on somatic stem cells of various adult human tissues. To investigate whether human corneal stroma also contains CD133-expressing cells and to analyze their functional features, stromal cells were isolated by collagenase digestion, immunophenotyped, and transferred to different culture systems to determine their stem cell properties as well as their differentiation potentials. For comparison, the embryonic keratocyte cell line EK1.Br, the dermal stromal cell line NHDF, and stromal cells of diseased corneas were studied. On average, 5.3% of the normal stromal cells expressed the stem cell marker CD133 and 3.6% co-expressed CD34. Expression of CD133 but not CD34 was also demonstrated for EK1.Br cells, whereas NHDF cells were negative for both markers. Further analysis of CD133(+) normal corneal cells revealed that a significant proportion displayed a monocytic phenotype with co-expression of CD45 and CD14. In diseased corneas, up to 26.8% of the stromal cells showed expression of CD133, and virtually all CD133(+) cells co-expressed CD14 but not CD45. Moreover, using a standard clonogenic assay, normal stromal cells had the capacity to form colonies of the macrophage lineage. These colonies could be further differentiated into lumican-expressing keratocytes. Our data suggest that the human corneal stroma harbors CD133(+) monocytic progenitor cells, which possess the potential to differentiate into the fibrocytic lineage. Thus, CD133(+) /CD45(+) /CD14(+) cells might represent stromal repair cells that differentiate into keratocytes via a CD133(+)/CD45()/CD14(+) intermediate stage. The findings from our study may shed new light on regenerative processes of the human corneal stroma.
authors.affiliation: Department of Ophthalmology, University Hospital Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Michelle
authors.initials: M
authors.lastname: Thill
authors.forename: Kathleen
authors.initials: K
authors.lastname: Schlagner
authors.forename: Sybille
authors.initials: S
authors.lastname: Altenähr
authors.forename: Süleyman
authors.initials: S
authors.lastname: Ergün
authors.forename: Richard G A
authors.initials: RG
authors.lastname: Faragher
authors.forename: Nerbil
authors.initials: N
authors.lastname: Kilic
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bednarz
authors.forename: Gabi
authors.initials: G
authors.lastname: Vohwinkel
authors.forename: Xavier
authors.initials: X
authors.lastname: Rogiers
authors.forename: Dieter K
authors.initials: DK
authors.lastname: Hossfeld
authors.forename: Gisbert
authors.initials: G
authors.lastname: Richard
authors.forename: Ursula M
authors.initials: UM
authors.lastname: Gehling
mesh_terms: D000071916:AC133 Antigen; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D015703:Antigens, CD / Q000378:metabolism; D018952:Antigens, CD34 / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D002469:Cell Separation; D002999:Clone Cells; D017364:Collagenases / Q000378:metabolism; D003114:Colony-Forming Units Assay; D003316:Corneal Diseases / Q000473:pathology; D003319:Corneal Stroma / Q000166:cytology*; D020405:Dermis / Q000166:cytology; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000166:cytology; D005434:Flow Cytometry; D006023:Glycoproteins / Q000378:metabolism; D006413:Hematopoietic System / Q000166:cytology; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D016850:Limbus Corneae / Q000166:cytology; D009363:Neoplasm Proteins / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D010641:Phenotype; D014945:Wound Healing
chemical_list: C116614:ABCG2 protein, human; D000071916:AC133 Antigen; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D015703:Antigens, CD; D018952:Antigens, CD34; D006023:Glycoproteins; D009363:Neoplasm Proteins; C000606023:PROM1 protein, human; D010455:Peptides; D017364:Collagenases