A recent study conducted by investigators from Cedars-Sinai and published in Diabetologia has identified how wound healing in the eye can be delayed by diabete, including the impact of the cornea.
Give me some background first.
Diabetes is known to be associated with such epigenetic modification in DNA methylation and miRNA changes.
When considering the cornea; however, diabetes can cause limbal epithelial stem cell (LESC) dysfunction—leading to persistent epithelial defects and an impaired ability to heal wounds.
What do current treatments target?
Standard therapies are designed to manage patients’ blood glucose levels and potentially prevent or delay the appearance of late-disease symptoms.
This focus necessitates a need to understand the molecular mechanism of wound healing issues associated with diabetes, according to Ruchi Shah, PhD, the study’s first author.
Now this research.
Investigators were looking to determine epigenetic alterations—specific DNA modifications that alter gene expression—in diabetic (vs non-diabetic) human limbal epithelial cells (LEC) as well as potential new diabetic markers that could be used as therapy to normalize corneal epithelial wound healing and stem cell expression.
How did they do this?
They compared the cornea cells of six diabetic patients to five non-diabetic patients by the following methods:
- DNA extraction from LEC for methylation analysis
- Protein extraction for Wnt phospho array analysis
- Wound healing (via a scratch assay in LEC)
Then what?
The investigators identified that the protein product (Wnt-5a) of the WNT5A gene—part of the WNT genes, which play a critical role in development, beginning before birth, and provide instructions for proteins involved in the body’s chemical signaling pathways—was repressed in the diabetic corneas.
Further, an increase in the microRNA that inhibits the WNT5A gene was also observed.
How did they normalize WNT5A?
Three methods were used:
- Adding protein directly
- Introducing a DNA methylation inhibitor
- Targeting microRNA levels with a novel gene therapy approach via a nanoscale compound.
To note, the compound was developed as a substitute for a viral gene therapy (which was found to be toxic to stem cells), according to Cedars-Sinai.
And the findings?
All methods were found to stimulate cell marker production and improve tissue regeneration—leading to an acceleration in wound healing by 1.4-fold in diabetic LEC.
So what’s next?
The investigators are continuing their research into WNT5A and other genes involved in wound healing as well as a potential combination therapy that could target both microRNA and DNA methylation while increasing (instead of repressing) the Wnt-5a protein.
Significance?
According to Clive Sendsen, PhD, co-study author, therapies that target reversing epigenetic effects may improve corneal function and prove significant for other diabetic complications.
And the end goal?
The investigators are hoping to develop topical, sustained-release drugs for corneal wound healing—specifically with the goal of becoming FDA approved.
Per Alexander Ljubimov, PhD, senior author of the research paper, these drugs, “may be one of the most promising approaches for effective future therapies.”