2013 Research Articles
A fish scale-derived collagen matrix as artificial cornea in rats: properties and potential
van Essen TH, Lin CC, Hussain AK, Maas S, Lai HJ, Linnartz H, van den Berg TJ, Salvatori DC, Luyten GP, Jager MJ.
Invest Ophthalmol Vis Sci. 2013 May 7 ;54(5):3224-33. doi: 10.1167/iovs.13-11799.
PURPOSE: A fish scale-derived collagen matrix (FSCM) is proposed as an alternative for human donor corneal tissue. Light scatter and light transmission of the FSCM were measured and compared with human cornea, and its short-term biocompatibility was tested in a rat model.
METHODS: Light scatter was determined with a straylight measuring device, whereas light transmission was measured using a broadband absorption spectrometer. for evaluation of the biocompatibiliy, three approaches were used: the FSCM was implanted as an anterior lamellar keratoplasty (ALK), placed in an interlamellar corneal pocket (IL), and placed subconjunctivally (SC). Transparency, neovascularization, and epithelial damage were followed for 21 days. Morphology and cellular infiltration were assessed histologically.
RESULTS: The amount of scattered light was comparable to that seen in early cataract and the percentage of light transmission was similar to the transmission through the human cornea. Implantation of the FSCM as an ALK led to mild haziness only, not obscuring the pupil, despite the development of neovascularization around the sutures; IL placement led to a moderate haze, partly obscuring the pupil, and to (partial) melting of the anterior corneal lamella. The SC group exhibited local swelling and induration, which decreased over time. Histology showed a chronic inflammation varying from mild and moderate in the ALK and IL group, to severe in the SC group.
CONCLUSIONS: In spite of technical difficulties, it was feasible to use the FSCM for ALK, whereas IL placement led to melting of the anterior lamella. Further studies are necessary for better understanding of its immunogenicity. The light scatter and transmission data show that the first version of this FSCM is comparable to human cornea tissue in this respect.
Characterization of corneal stromal stem cells with the potential for epithelial transdifferentiation.
Hashmani K, Branch MJ, Sidney LE, Dhillon PS, Verma M, McIntosh OD, Hopkinson A, Dua HS.
Stem Cell Res Ther. 2013 Jun 24;4(3):75. doi: 10.1186/scrt226.
INTRODUCTION: The corneal stroma is being increasingly recognized as a repository for stem cells. Like the limbal and endothelial niches, stromal stem cells often reside in the peripheral cornea and limbus. These peripheral and limbal corneal stromal cells (PLCSCs) are known to produce mesenchymal stem cells in vitro. Recently, a common corneal stromal and epithelial progenitor was hinted at. This study aims to examine the stem cell potential of corneal stromal cells and to investigate their epithelial transdifferentiation ability.
METHODS: PLCSCs were grown in traditional Dulbecco modified Eagle medium (DMEM)-based keratocyte culture medium and an M199-based medium and analyzed for a profile of cell-surface markers by using flow cytometry and differentiated into mesenchymal phenotypes analyzed with quantitative polymerase chain reaction (qPCR) and histologic staining. PLCSCs in M199 were subsequently divided into subpopulations based on CD34 and CD105 expression by using fluorescence- activated cell sorting (FACS). Subpopulations were characterized by marker profile and mesenchymal differentiation ability. Both whole PLCSCs and subpopulations were also cultured for epithelial transdifferentiation.
RESULTS: Cells cultured in M199 demonstrated a more stem-like cell-surface marker profile, and the keratocyte marker CD34 was retained for several passages but absent in cells cultured in DMEM. Cells cultured in M199 also exhibited a greater mesenchymal differentiation potential, compared with DMEM. PLCSCs could be divided into CD34(+)CD105(+), CD34-CD105(+), and CD34-CD105- subpopulations, of which CD34(+)CD105(+) cells were the most stemlike with regard to marker expression and mesenchymal differentiation potential. Subpopulations of PLCSCs exhibited differing abilities to transdifferentiate into epithelial phenotypes. Cells that were initially CD34(+)CD105(+) showed the greatest differentiation potential, producing CK3(+) and CK19(+) cells, and expressed a range of both epithelial progenitor (HES1, FRZB1, DCT, SOD2, ABCG2, CDH1, KRT19) and terminally differentiated (DSG3, KRT3, KRT12, KRT24) genes.
CONCLUSIONS: Culture medium has a significant effect on the phenotype and differentiation capacity of PLCSCs. The stroma contains a heterogeneous cell population in which we have identified CD34(+) cells as a stem cell population with a capacity for mesenchymal and epithelial differentiation.