A micelle-shedding thermosensitive hydrogel as sustained release formulation.

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Thermosensitive hydrogels offer potential for controlled drug release.
• Paclitaxel (PTX) is a potent chemotherapeutic agent with limited aqueous solubility.
• Developing effective delivery systems for PTX is crucial for cancer treatment.

Purpose of the Study:

• To investigate the micelle release and drug solubilization capabilities of pNIPAm-PEG-pNIPAm hydrogels.
• To evaluate the in vivo performance of PTX-loaded hydrogels for sustained systemic delivery.
• To assess the anti-tumor efficacy and tolerability of this novel hydrogel formulation.

Main Methods:

• Fabrication of pNIPAm-PEG-pNIPAm hydrogels and loading with paclitaxel (PTX).
• In vitro assessment of micelle release and PTX solubilization in refreshed and non-refreshed media.
• In vivo study in tumor-bearing mice involving intraperitoneal administration of PTX-loaded hydrogels at varying doses.
• Pharmacokinetic analysis of PTX serum levels, elimination half-life, and bioavailability.
• Evaluation of tumor growth inhibition over time.

Main Results:

• pNIPAm-PEG-pNIPAm hydrogels continuously released flower-like micelles, which solubilized PTX above its aqueous solubility limit.
• In vivo administration of PTX-loaded hydrogels was well-tolerated, with no acute systemic toxicity observed.
• Sustained PTX release was confirmed by a long elimination half-life (7.4 h) and 100% bioavailability.
• A single injection of the highest dose formulation completely inhibited tumor growth for at least 3 weeks.

Conclusions:

• Micelle-releasing pNIPAm-PEG-pNIPAm hydrogels represent a promising platform for sustained and metronomic delivery of chemotherapeutics like PTX.
• This hydrogel system demonstrates significant potential as a depot formulation for enhanced cancer therapy.
• The study highlights a novel approach for improving the therapeutic index of poorly soluble anti-cancer drugs.