RGD modified PLGA/gelatin microspheres as microcarriers for chondrocyte delivery

Poly(lactide-co-glycotide) (PLGA)/gelatin composite microspheres were prepared by an emulsion solvent evaporation technique. RGDS peptides were further immobilized under the catalyzation of water soluble carbodiimide (EDAC). Confocal laser scanning microscopy and transmission electron microscopy revealed that the gelatin was entrapped in the PLGA/gelatin microspheres with a manner of separated domains. The contents of the entrapped gelatin and immobilized RGDS peptides were quantified as 0.9 mg/20 mg and approximately 2.1 microg/20 mg microspheres by hydroxyproline analysis and bicinchoninic acid protein assay, respectively. Moreover, difference in morphology of PLGA, PLGA/gelatin and RGDS modified PLGA/gelatin (PLGA/gelatin-RGDS) microspheres was observed by scanning electron microscopy. The PLGA/gelatin and PLGA/gelatin-RGDS microspheres lost their weight rapidly in PBS, but slowly in DMEM/fetal bovine serum. Rabbit auricular chondrocytes were seeded onto the microspheres in vitro to assess their biological performance and applicability as cell carriers. Results show that amongst the PLGA, PLGA/gelatin and PLGA/gelatin-RGDS microspheres, the latter ones have the best performance in terms of chondrocyte attachment, proliferation, viability and sulfated glycosaminoglycans secretion.