Mapping molecular differences and extracellular matrix gene expression in segmental outflow pathways of the human ocular trabecular meshwork

Janice Vranka, John M. Bradley, Yong Feng Yang, Kate Keller, Ted Acott

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Elevated intraocular pressure (IOP) is the primary risk factor for glaucoma, and lowering IOP remains the only effective treatment for glaucoma. The trabecular meshwork (TM) in the anterior chamber of the eye regulates IOP by generating resistance to aqueous humor outflow. Aqueous humor outflow is segmental, but molecular differences between high and low outflow regions of the TM are poorly understood. In this study, flow regions of the TM were characterized using fluorescent tracers and PCR arrays. Anterior segments from human donor eyes were perfused at physiological pressure in an ex vivo organ culture system. Fluorescently-labeled microspheres of various sizes were perfused into anterior segments to label flow regions. Actively perfused microspheres were segmentally distributed, whereas microspheres soaked passively into anterior segments uniformly labeled the TM and surrounding tissues with no apparent segmentation. Cell-tracker quantum dots (20 nm) were localized to the outer uveal and corneoscleral TM, whereas larger, modified microspheres (200 nm) localized throughout the TM layers and Schlemm ' s canal. Distribution of fluorescent tracers demonstrated a variable labeling pattern on both a macro- and microscale. Quantitative PCR arrays allowed identification of a variety of extracellular matrix genes differentially expressed in high and low flow regions of the TM. Several collagen genes (COL16A1, COL4A2, COL6A1 and 2) and MMPs (1, 2, 3) were enriched in high, whereas COL15A1, and MMP16 were enriched in low flow regions. Matrix metalloproteinase activity was similar in high and low regions using a quantitative FRET peptide assay, whereas protein levels in tissues showed modest regional differences. These gene and protein differences across regions of the TM provide further evidence for a molecular basis of segmental flow routes within the aqueous outflow pathway. New insight into the molecular mechanisms of segmental aqueous outflow may aid in the design and delivery of improved treatments for glaucoma patients.

Original languageEnglish (US)
Article numbere0122483
JournalPLoS One
Volume10
Issue number3
DOIs
StatePublished - Mar 31 2015

Fingerprint

Trabecular Meshwork
Microspheres
extracellular matrix
Gene expression
chromosome mapping
Extracellular Matrix
eyes
glaucoma
Gene Expression
gene expression
Matrix Metalloproteinases
Genes
Intraocular Pressure
Glaucoma
Tissue
tracer techniques
water
Aqueous Humor
quantum dots
interstitial collagenase

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Mapping molecular differences and extracellular matrix gene expression in segmental outflow pathways of the human ocular trabecular meshwork. / Vranka, Janice; Bradley, John M.; Yang, Yong Feng; Keller, Kate; Acott, Ted.

In: PLoS One, Vol. 10, No. 3, e0122483, 31.03.2015.

Research output: Contribution to journalArticle

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