Coronary arteries angiogenesis in ischemic myocardium: biocompatibility and biodegradability of various hydrogels

To evaluate the biocompatibility and biodegradability of various hydrogels and choose suitable hydrogels for the coronary arteries angiogenesis in ischemic myocardium, we synthesized six kinds of hyaluronan hydrogels, fibrin hydrogel, poly(vinyl alcohol)-chitosan hydrogel, and obtained elastin hydrogels. We examined their degradation rates and cytotoxicity in vitro. Then, hydrogels were implanted into rat adductor muscles for 1, 2, or 4 weeks. Hydrogels and surrounding tissues were resected, followed by hematoxylin and eosin staining, Masson's trichrome staining, and immunohistochemical staining for measurements of degradation, immune response, and angiogenesis. 2-Iminothiolane grafted hyaluronan hydrogel and periodate oxidated hyaluronan hydrogel presented rapid degradation rates, low quantity of inflammation-mediating cells (12 +/- 3 and 12 +/- 4 per 2.5 x 10(-3) mm(2), respectively, at week 2), thin fibrous capsules (scores were 3.8 +/- 0.1 and 4.0 +/- 0.3 per 0.33 mm(2), respectively, at week 2) with dense blood vessels in the areas surrounding the implanted hydrogels. 2-Iminothiolane grafted hyaluronan and periodate oxidated hyaluronan hydrogels with appropriate degradation rates and low immune responses were suitable for coronary arteries angiogenesis in ischemic myocardium.