[Comparison of characteristics between glutaraldehyde- and genipin-crosslinked gelatin microspheres]

To compare the characteristics of gelatin microspheres crosslinked by glutaraldehyde (GA) or genipin (GP).

Gelatin microspheres, prepared by the improved emulsified cold-condensation method, were crosslinked by GP and GA, respectively. After being dispersed in PBS, two kinds of microspheres with 60% degree of cross linking were compared in terms of morphology, swelling and degrading properties. rhBMP-2 were loaded into the GP and GA microspheres, and the encapsulation rate, drug loading and releasing capacity were measured; 100%, 50% and 25% leaching liquid of GP and GA microspheres were respectively cultured with rat osteoblast (DMEM group as the control), and cell proliferation was measured by MTT method to grade the cell cytotoxicity.

GP and GA microspheres were both spherical with the diameters of (78 +/- 18) microm and (65 +/- 10) microm, and there were no difference between both microspheres in drug loading and encapsulation rate. But, GP microspheres, with long degrading period (28 days) compared to GA microspheres (21 days), had better dispersibility, and swelling rate (89.0% +/- 4.8%), the percentage of cumulative drug releasing at 10 days (78.80% +/- 4.96%) were both lower than GA microsphere (118.0% +/- 7.6%, 90.50% +/- 5.12%). The percentages of drug loading of GP and GA were (921 +/- 73) and (965 +/- 62) ng/g, and the encapsulation rates were 88.5% +/- 2.1% and 89.7% +/- 1.8%; showing no significant difference (P > 0.05). The cell cytotoxicity of 100%, 50% and 25% leaching liquid of GP microspheres was all at the level I, but leaching liquid of GA microspheres with corresponding concentration were at the levels of III, III and II.

GP crosslinked gelatin microspheres are superior to GA crosslinked gelatin microspheres and can be widely used in tissue engineering field.