Biodegradation and tissue integration of various polyethylene glycol matrices: a comparative study in rabbits.

Abstract

To test whether or not chemical and/or physical modifications of polyethylene glycol (PEG) hydrogels influence degradation time, matrix/membrane stability, and integration into surrounding hard and soft tissues. In 28 rabbits, six treatment modalities were randomly applied to six sites on the rabbit skull: a dense network PEG hydrogel (PEG HD), a medium-dense network PEG hydrogel (PEG MD), a medium-dense network PEG hydrogel modified with an RGD sequence (PEG MD/RGD), a medium-dense network PEG hydrogel modified with RGD with reduced carboxymethyl cellulose (PEG MD/RGD_LV), a loose network PEG hydrogel modified with RGD (PEG LD/RGD), and a collagen membrane (BG). Descriptive histology and histomorphometry were performed at 1, 2, 4, and 6weeks. PEG HD revealed the highest percentage of residual matrix at all time points starting with 47.2% (95% CI: 32.8-63.8%) at 1week and ending with 23.4% (95% CI: 10.3-49.8%) at 6weeks. The hydrogel with the loosest network (PEG LD/RGD) was stable the first 2weeks and then degraded continuously with a final area of 8.3% (95% CI: 3.2-21.2%). PEG HD was the most stable and densely stained membrane, whereas PEG MD and PEG LD matrices integrated faster, but started to degrade to a higher degree between 2 and 4weeks. PEG MD degradation was dependent on the addition of RGD and the amount of CMC. Chemical and/or physical modifications of PEG hydrogels influenced matrix stability. PEG MD/RGD demonstrated an optimal balance between degradation time and integration into the surrounding soft and hard tissues.