A new highly transparent injectable PHA-based thermogelling vitreous substitute

Area of Science:

• Biomaterials Science
• Ophthalmology
• Polymer Chemistry

Background:

• Transparency is crucial for ocular biomaterials, especially vitreous substitutes.
• Understanding hydrogel transparency limits is essential for developing effective implants.
• Biodegradable polyurethane thermogels offer potential for ocular applications.

Purpose of the Study:

• To investigate the relationship between poly[(R)-3-hydroxybutyrate-(R)-3-hydroxyhexanoate] (PHBHx) content and transparency in biodegradable thermogels.
• To evaluate the suitability of PHBHx-based thermogels as injectable vitreous substitutes.
• To assess the in vivo biocompatibility and transparency retention of a selected hydrogel in a rabbit eye model.

Main Methods:

• Tuning the PHBHx content in biodegradable polyurethane thermogels.
• Measuring light transmittance and gel properties.
• Implanting the PHxEP-0.5 hydrogel in rabbit eyes for 6 months.
• Assessing transparency, inflammation, and retinal structure preservation post-implantation.

Main Results:

• Hydrophobic PHBHx content directly correlated with hydrogel cloudiness.
• PHxEP-0.5 hydrogel demonstrated high light transmittance and suitable gel properties.
• The PHxEP-0.5 hydrogel maintained transparency in vivo, unlike cloudy controls.
• Negligible inflammation and preserved retinal structure were observed over 6 months.

Conclusions:

• PHBHx-based thermogels can be engineered for tunable transparency.
• The PHxEP-0.5 hydrogel is biocompatible and maintains transparency in the rabbit eye.
• These findings support the development of next-generation injectable transparent vitreous substitutes.