June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
Gellan Hydrogel Eyedrop Promotes Wound Healing and Prevents Fibrosis of Cornea by Preferentially Absorbing Pro-Fibrotic Proteins
Author Affiliations & Notes
  • Rachel Caroline Vincent
    Chemical Engineering, University of Birmingham, Birmingham, Birmingham, United Kingdom
    Institute of Inflammation and Ageing, University of Birmingham, Birmingham, Birmingham, United Kingdom
  • Richard J.A. Moakes
    Chemical Engineering, University of Birmingham, Birmingham, Birmingham, United Kingdom
  • Gibran Farook Butt
    Academic Unit of Opthamology, University of Birmingham, Birmingham, Birmingham, United Kingdom
    Birmingham and Midlands Eye Centre, Sandwell and West Birmingham Hospitals NHS Trust, Birmingham, Birmingham, United Kingdom
  • Anthony D. Metcalfe
    Chemical Engineering, University of Birmingham, Birmingham, Birmingham, United Kingdom
  • Richard L. Williams
    Chemical Engineering, University of Birmingham, Birmingham, Birmingham, United Kingdom
  • Graham R Wallace
    Institute of Inflammation and Ageing, University of Birmingham, Birmingham, Birmingham, United Kingdom
  • Ann Logan
    Biomedical Sciences, University of Warwick, Coventry, West Midlands, United Kingdom
  • Saaeha Rauz
    Institute of Inflammation and Ageing, University of Birmingham, Birmingham, Birmingham, United Kingdom
    Birmingham and Midlands Eye Centre, Sandwell and West Birmingham Hospitals NHS Trust, Birmingham, Birmingham, United Kingdom
  • Liam M Grover
    Chemical Engineering, University of Birmingham, Birmingham, Birmingham, United Kingdom
  • Footnotes
    Commercial Relationships   Rachel Vincent, None; Richard Moakes, University of Birmingham (P); Gibran Butt, None; Anthony Metcalfe, University of Birmingham (P); Richard Williams, University of Birmingham (P); Graham Wallace, None; Ann Logan, None; Saaeha Rauz, None; Liam Grover, University of Birmingham (P)
  • Footnotes
    Support  Medical Research Council Developmental Pathway Funding Scheme (MR/N019016/1) and the National Institute for Health Research (II-LA-1117-20001)
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 938. doi:
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      Rachel Caroline Vincent, Richard J.A. Moakes, Gibran Farook Butt, Anthony D. Metcalfe, Richard L. Williams, Graham R Wallace, Ann Logan, Saaeha Rauz, Liam M Grover; Gellan Hydrogel Eyedrop Promotes Wound Healing and Prevents Fibrosis of Cornea by Preferentially Absorbing Pro-Fibrotic Proteins. Invest. Ophthalmol. Vis. Sci. 2021;62(8):938.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Corneal opacity is a leading cause of sight impairment worldwide. Gellan gum is a water soluble, anionic polysaccharide that, may be used to form optically clear fluid gel eyedrops. Previously, it has been shown that gellan fluid gel (FG) significantly reduces markers of corneal scarring in a murine model of microbial keratitis. This study looks into why gellan FG is so effective at preventing fibrosis and scarring.

Methods : Cultured human primary corneal fibroblasts were treated with 5 ng/ml Transforming Growth Factor b1 (TGFb1) with or without 27.5% v/v gellan FG. Samples were analysed for changes in expression of mRNA after 24 and 80 hours by RT-PCR. Cultured human dermal primary fibroblasts were treated with 10 ng/ml TGFb1 with or without 20% v/v gellan FG. Samples were analysed for total collagen content using a hydroxyproline assay. Data analysed using unpaired t-test.

Affinity of different proteins for quiescent and fluid gels was compared by incubating equal volumes of hydrogel and phosphate buffered saline (PBS) contain protein. Rate of absorption for each protein was determined by measuring the amount of protein remaining in the PBS was measured using a total protein assay or ELISA at multiple time points.

Results : Gellan FG significantly inhibited TGFb1 mediated upregulation of smooth muscle actin a, fibronectin, collagen 1A1 and collagen 3A1 mRNA expression in human corneal fibroblasts (p<0.05), indicating an anti-scarring effect. Gellan FG also prevented TGFb1 stimulated collagen production in human dermal fibroblasts (p<0.01).
Proteins with a net positive charge under physiological conditions (isoelectric point (pI) >7) have a significantly higher affinity for gellan than those with a neutral or net negative charge (pI = or <7). Gellan eye drop absorbed 80% of fibrogenic TGFb1 (pI = 8.6), but only 22% of Epidermal Growth Factor (pI = 4.5). Hydrogel made from agarose, an uncharged polysaccharide, did not preferentially absorb proteins depending upon their net charge.

Conclusions : In addition to mechanically protecting the wound bed and providing lubrication, gellan FG absorbs and sequesters proteins from the wound bed by diffusion coupled with electrostatic association. The gellan dressing alters the trophic profile of the wound and reprograms the extracellular signalling microenvironment by selectively absorbing proteins.

This is a 2021 ARVO Annual Meeting abstract.

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