Illustration of grape turning into an eye with a healthy retina in the background, symbolizing the protective effects of grape seed extract on vision in diabetic retinopathy.

Grape Seed Extract: A Sweet Solution for Diabetic Retinopathy?

Theo Raines in Health & Wellness December 2025 • 4 min read.

"New research suggests that grape seed proanthocyanidin extract may protect against neurodegeneration in diabetic retinopathy by boosting thioredoxin levels."

Diabetic retinopathy, a common complication of diabetes, has long been recognized as a microvascular disease affecting the small blood vessels in the retina. However, recent research is shedding light on another critical aspect: its potential as a neurodegenerative disease. This means that in addition to blood vessel damage, the nerve cells in the retina, which are responsible for vision, are also at risk.

The race is on to understand the intricate molecular mechanisms that drive the development of diabetic retinopathy. Finding these mechanisms is crucial for creating effective strategies to prevent and treat this condition, which is a leading cause of vision loss worldwide.

In a promising new study, researchers investigated the potential of grape seed proanthocyanidin extract (GSPE) to protect against nerve cell damage in a high-glucose environment, mimicking the conditions of diabetes. The study focused on GSPE's ability to increase the expression of thioredoxin (Trx), a protein known for its protective properties. The findings suggest that GSPE may hold promise as a novel agent in the fight against neurodegenerative diseases like diabetic retinopathy.

How Does Grape Seed Extract Protect Retinal Cells?

Illustration of grape turning into an eye with a healthy retina in the background, symbolizing the protective effects of grape seed extract on vision in diabetic retinopathy.

The study, published in Molecular Medicine Reports, delved into the protective effects of GSPE on retinal cells under hyperglycemic conditions, both in vitro (in cell cultures) and in vivo (in a mouse model of diabetes). The researchers aimed to determine if GSPE could counteract the damaging effects of high glucose levels on retinal neurons.

Here’s a breakdown of the key methods and findings:

Cell Morphology and Apoptosis: Hematoxylin and eosin staining was used to examine the structure of retinal neurons. Flow cytometry and a TUNEL assay were employed to detect and measure cell death (apoptosis).
Gene and Protein Expression: RT-qPCR and Western blot analysis were performed to assess the levels of mRNA and protein expression of target genes, including thioredoxin (Trx), glucose-regulated protein 78 (GRP78), and apoptosis-related proteins.
In Vivo Mouse Model: Diabetic mice were treated with GSPE, and their retinas were examined for signs of damage and Trx expression.
Key In Vitro Findings:
- High glucose conditions increased the expression of GRP78, an indicator of endoplasmic reticulum (ER) stress.
- High glucose conditions decreased Trx expression and increased cell apoptosis.
- GSPE treatment reversed these effects, inhibiting neurodegeneration.
- Blocking Trx with an inhibitor (PX12) reduced GSPE's protective effects.
Key In Vivo Findings:
- Diabetic mice showed damage to photoreceptor cells.
- GSPE treatment protected against this damage.
- GSPE increased Trx mRNA expression in the retina.

These findings suggest that GSPE protects retinal cells from glucose-induced damage, at least in part, by increasing Trx expression and reducing ER stress and apoptosis.

The Future of Grape Seed Extract in Diabetic Retinopathy Treatment

This research offers a promising step forward in understanding how GSPE may protect against the neurodegenerative aspects of diabetic retinopathy. By increasing Trx levels and mitigating ER stress, GSPE appears to activate key defense mechanisms within retinal cells. While further research is needed, these findings suggest that GSPE, or similar compounds that boost Trx activity, could be a valuable addition to the strategies used to combat diabetic retinopathy and preserve vision.

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Everything You Need To Know

What exactly is grape seed proanthocyanidin extract (GSPE), and why is it being researched for diabetic retinopathy?

Grape seed proanthocyanidin extract, often called GSPE, is a substance derived from grape seeds. It's being studied for its potential protective effects against nerve cell damage in conditions like diabetic retinopathy. GSPE appears to work by boosting the levels of a protective protein called thioredoxin (Trx) and reducing endoplasmic reticulum (ER) stress. This is significant because it suggests GSPE could activate defense mechanisms within retinal cells, offering a new approach to combatting vision loss associated with diabetes. More research is needed to explore the full potential of GSPE.

What is diabetic retinopathy, and why is it considered a neurodegenerative disease?

Diabetic retinopathy is a complication of diabetes that affects the retina, the light-sensitive tissue at the back of the eye. While it's known as a microvascular disease affecting blood vessels, research indicates it also involves neurodegeneration, meaning damage to nerve cells in the retina. This is important because these nerve cells are essential for vision. Addressing both vascular and nerve cell damage is crucial for preventing vision loss. Treatments that can protect these nerve cells, like those involving grape seed proanthocyanidin extract, could be very valuable.

What is thioredoxin (Trx), and what role does it play in protecting retinal cells?

Thioredoxin, or Trx, is a protein known for its protective properties within cells. In the context of diabetic retinopathy, it's significant because studies show that grape seed proanthocyanidin extract (GSPE) can increase Trx expression in retinal cells. By increasing Trx levels, GSPE appears to protect these cells from damage caused by high glucose levels, reducing endoplasmic reticulum stress and apoptosis (cell death). Thioredoxin's protective action makes it a key target in strategies to combat neurodegenerative diseases like diabetic retinopathy.

What methods were used to determine the effectiveness of Grape Seed Extract?

The study utilized in vitro (cell cultures) and in vivo (mouse model) experiments to investigate the protective effects of grape seed proanthocyanidin extract (GSPE) on retinal cells under hyperglycemic conditions. In vitro, cell morphology and apoptosis were assessed using staining and flow cytometry. Gene and protein expression, particularly of thioredoxin (Trx) and apoptosis-related proteins, were evaluated using RT-qPCR and Western blot analysis. In vivo, diabetic mice were treated with GSPE, and their retinas were examined for damage and Trx expression. These methods collectively provided insights into how GSPE counteracts the damaging effects of high glucose levels on retinal neurons.

What did the research show about how grape seed proanthocyanidin extract (GSPE) impacts diabetic retinopathy?

The study indicated that grape seed proanthocyanidin extract (GSPE) increases the expression of thioredoxin (Trx), which seems to protect retinal cells from damage caused by high glucose levels, a hallmark of diabetes. Specifically, GSPE appears to reduce endoplasmic reticulum (ER) stress and apoptosis (cell death) in these cells. These findings suggest that GSPE, or similar compounds that boost Trx activity, could be a valuable addition to strategies used to combat diabetic retinopathy. However, it's important to remember that this research is preliminary, and further studies are needed to confirm these benefits and determine the optimal use of GSPE in treating this condition.