characterize their property,and investigate their
effect on the proliferation of human periodontal ligament cells (hPDLCs)and on the number of osteoclasts in the
pressure sides of the periodontal tissues of rats.
Methods: SP-PLGA NP were prepared by double emulsion-solvent evaporation method.
The proliferation of hPDLCs were evaluated on different day by MTT method after SP-PLGA nanoparticles were added into the culture medium.
SP-PLGA NP was injected into the subgingival
part of the root tip of the rats after orthodontic forces was applied,then the maxilla of the rats was separated on the 1st,3rd,7th,14th day respectively and HE slices were made.The tissue change and the number of osteoclasts in the pressure sides of the periodontal tissues of rats were observed.In each experiment,SP group and blank group were set up as control.
Results: The SP-PLGA NP were spherical,with mean diameter of114.56±21.42nm.The celluar study showed no significant difference in OD(optical density )value among the three groups on the first day of plate culture;the OD value of the SP group was higher than that of the other two groups on the third day ; the OD value in the SP-loaded PLGA nanoparticles group was the highest after 5 days.
The HE slices shows: no osteoclasts was found after orthodontic force was applied 1 day later; after 3 days,the sequence of OC
numbers was SP group©ƒSP-PLGA NP group©ƒ©ƒblank control group ;after 7 days,the Osteoclast number was SP-PLGA NP group©ƒSP group©ƒblank control group;after 14 days,SP-PLGA NP group remained the highest.
Conclusion: The SP-PLGA nanoparticles can release SP continuously and promote the proliferation of PDLCs in vitro for a relatively longer time.
Substance P could promote the formation of osteaclasts during orthodontics and SP-PLGA NP could maintain this effect for a longer time.