Poly(ethylene glycol) methacrylate hydrolyzable microspheres for transient vascular embolization

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Hydrolyzable microspheres are crucial for various biomedical applications, including drug delivery and tissue engineering.
• Developing safe and rapidly degrading materials is essential to minimize long-term complications and immune responses.
• Poly(ethylene glycol) methacrylate (PEGMA) offers tunable properties for creating advanced biomaterials.

Purpose of the Study:

• To synthesize and characterize novel hydrolyzable microspheres based on PEGMA for biomedical applications.
• To evaluate the degradation kinetics, degradation products, and biocompatibility of these PEGMA microspheres.
• To assess the in vivo performance and inflammatory response of the microspheres in a subcutaneous implantation model.

Main Methods:

• Suspension polymerization was used to prepare PEGMA microspheres incorporating methacrylic acid and 2-methylene-1,3-dioxepane (MDO).
• Microsphere properties including size, shape, swelling, and injectability were analyzed.
• In vitro hydrolytic degradation studies were conducted in phosphate-buffered saline (PBS) at 37 °C.
• Cytotoxicity was assessed using L929 fibroblasts.
• In vivo studies involved subcutaneous implantation in a rabbit model.

Main Results:

• Synthesized microspheres were spherical, in the 300-500 μm range, injectable, and swelled in PBS.
• All formulations completely degraded within 2 days in PBS at 37 °C.
• Degradation products included low-molecular-weight compounds and water-soluble polymethacrylate chains below the renal filtration threshold (for MDO-containing microspheres).
• Both microspheres and their degradation products exhibited minimal cytotoxicity.
• In vivo implantation confirmed rapid degradation and elicited only a mild, transient inflammatory response.

Conclusions:

• PEGMA-based hydrolyzable microspheres can be readily prepared with desirable characteristics for biomedical use.
• These microspheres demonstrate rapid in vitro and in vivo degradation with minimal cytotoxicity.
• The incorporation of MDO yields degradation products that are cleared by renal filtration.
• The findings support the potential of these PEGMA microspheres as safe and effective biomedical materials.