Preparation Of RhBMP2Sustained Release Microspheres And Its Experimental Study For Pulp Capping Agent

Vital pulp therapy in the treatment of dental pulp disease is most consistent withbiological point of view, pulp capping agent plays a decisive role in the treatment,therefore, continuously improve the capping agent is very important. In the numerouspulp capping materials used at present, bone morphogenetic protein (BMP) is one of thematerial has been widespread concern, especially BMP2, it is closely associated withdentin formation and tooth development. It has been reported that BMP2used as pulpcapping treatment, a short period of time will be the formation of a large number ofreparative dentin exposed pulp hole closed, can be beneficial to restoration of dental pulp. But when BMP2in vivo application, will soon be diluted or by proteinase,effect of timeon dental pulp cells in short, can not effectively play its biological properties; unable toprovide support for the formation of dentin, which is limited in clinical application.In recent years, with the development of biodegradable material as the carrierpreparation technology, more and more study on protein and peptide carrier systems. Thepoly lactic acid-glycolic acid copolymer (PLGA) for better compatibility, biodegradable,non-toxic; material and its degradation products without obvious adverse reaction ofpeptides and proteins, the United States has received FDA approval for clinical. TakingPLGA as the carrier of the preparation of BMP2microspheres can solve the shortage ofBMP2in application, it can play a sustained release effect; and can protect the activity ofrelated factors. In this study to explore the method of preparation of microsphere usingBSA as model protein and PLGA as controlled-release carrier, optimize the preparationtechniques and prescription composition. Preparation of W/O/W BSA-PLGAmicrospheres by double emulsion solvent evaporation method; change the relatedinfluence factors of microsphere preparation, based on encapsulation efficiency, surfacemorphology observation and the24h burst release, the BSA dosage is10mg, externalPVA concentration10g/L, NaCl concentration is50g/L, homogenizing speed doubleemulsion the10000r/min microspheres prepared by24h burst release quantity small,morphology of microsphere are round and uniform, smooth surface, no adhesion.Experiment two used in optimization of rhBMP2-PLGA sustained releasemicrospheres were prepared for observation of microspheres preparation conditions, thesurface morphology by scanning electron microscope, using the Malvin laser particle sizeanalyzer determine the particle size, determination of microspheres by ELISA method,encapsulation efficiency, drug loading and in vitro release of the1d,3d,7d,14d,28dmicrospheres release. The results show that the optimization process: rhBMP2-PLGAmicrospheres prepared white powder, no collapse phenomenon; morphology ofmicrosphere are round and uniform, smooth surface, no adhesion; particle sizedistribution is normal distribution, distribution center in between3um~4um, theencapsulation efficiency was72.5%±4.17%, drug loading rate was0.38%±0.24%. The amount released was19.36%±1.83%rhBMP2-PLGA microspheres in vitro release1D,performance for the burst release of drug, which is mainly caused by the release ofmicrosphere surface, then released more slowly, but the cumulative release amountincreased continuously, to28d to52.76%±3.7%. With suitable particle size wasprepared by W/O/W emulsion solvent evaporation method, form uniform completerhBMP2-PLGA microspheres. Has sustained release effect and good biological activity,can long time gradually release of growth factors, is an ideal carrier for growth factor anddelivery system.Experiment three using2healthy beagle dogs as the experimental object, selected42teeth,42teeth were randomly divided into7groups (rhBMP2, rhBMP2-PLGAmicrospheres, collagen, dental special antibiotics, antibiotic+rhBMP2-PLGAmicrospheres, collagen+rhBMP2-PLGA microspheres, blank control group), each grouphad6teeth. In the experiment the occlusal surface mechanical exposed pulp, and afterprocessing the material covered in the pulp on the section, three months after MicroCTobservation of dentin bridge formation. The results show that: rhBMP2can be observedin intact dentin calcification bridge formation, other than less; dentin bridge purecollagen can also generate a complete by separate use of collagen, showed that collagencan induce dental pulp cell differentiation and dentin; But the separate use of dentalspecial antibiotics, dentin formation is poor, that antibiotics without inducing effect ondental pulp cells; RhBMP2-PLGA used alone without composite dental specialantibiotics or collagen is generated when the dentin bridge thick, But the formation ofdentin bridge thick in the pure collagen. HE staining slice shows rhBMP2group,rhBMP2-PLGA and collagen dentin bridge is given priority to with osteoid dentin;Antibiotics and rhBMP2-PLGA mixture mixed with collagen and rhBMP2-PLGAgroup of dentin bridge is given priority to with dentine tube sample. So the use ofantibiotics and rhBMP2-PLGA composite dental pulp capping, on dental pulp celldifferentiation than the other group of strong, thick and complete formation of dentinbridge at the same time, with the pulp capping effect good, for clinical provide thefeasibility for...