How degradable gel microspheres behave inside joints to deliver drugs over time

One week post-injection, both types of microspheres were localized beneath the synovial lining of the sheep shoulder joint.

• Both degradable and non-degradable microspheres were found beneath the synovial lining after one week.
• A portion of the microspheres remained in the synovial fluid.
• Histological analysis revealed cell proliferation around non-degradable microspheres after one and four weeks.
• Degradable PEG-hydrogel microspheres were surrounded by fewer cells compared to non-degradable microspheres.
• The degradation of PEG-hydrogel microspheres was slow and not complete after four weeks.
• Degradable PEG-hydrogel microspheres triggered a lower intensity of inflammatory reactions in the synovium compared to non-degradable microspheres.

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