Abstract: Objective　To prepare enamel matrix proteins (EMPs) loaded dextran-based hydrogel microspheres (EMPs-dex- MPs), and to evaluate their EMPs controlled release property and their biological effects on the proliferation and differentiation of human periodontal ligament cells (PDLCs)in vitro.Methods　Using dimethylbenzene as the oil phase, EMPs-dex-MPs were achieved by emulsion-chemical crosslinking technique. The process of the recombination preparation was optimized by orthogonal factorization method. The configuration and size of EMPs-dex-MPs were determined by scanning electron microscope. The EMPs loading content and encapsulation rate of EMPs-dex-MPs, and their biodegradation characteristic were studied by routine analysis methods. Dynamic dialysis method was used to determine the release characteristic of EMPs-dex-MPsin vitroand its influencing factors. The proliferation of cultured PDLCswas measured byMTTmethod and the differentiation of PDLCswas measured by their alkaline phosphatase (ALP) activities.Results　The results showed that EMPs-dex-MPswere homogenous and stable with the av- erage diameter 25μm, and the EMPs loading content was (32·8±1·2)%, the encapsulation rate was (78·9±1·0)%. Under 9% physiological saline solution contained a very thimbleful quantity of dextranase EMPs-dex-MPs could be biodegraded complete- ly during about 40 days. Theinvitroexperiments showed that about 80% of EMPs could be released out in 20 days. Using EMPs- dex-MPs could enhance the proliferation responses and ALP activities of PDLCs more than 12 days.Conclusion　As a new sus- tained release system of growth factors,the dex-MPs is stable, workable and biodegradable. EMPs-dex-MPs, whose drug release can be controlled by preparation technique, may be more effective in promoting periodontal tissue regeneration.

Key words: enamel matrix proteins, dextran, microsphere, controlled release