Investigation And Preparation Of HA/PTMC-F127-PTMC Materials For Induceing Osteogenic Differentiation

Trauma,infection,skeletal diseases,and congenital malformations often result in large bone defects.Autografts and allografts are considered current effective treatments,but both have potential risks.It remains a challenge for the repair of bone defects in clinical treatment.Tissue engineering is considered as a promising alternative to the conventional use of bone grafts.PTMC-F127-PTMC has received increasing interest as a matrix material in bone regeneration due to its outstanding mechanical strength,biocompatibility and slow degradation rate.Here,PTMC-F127-PTMC were used as templates to regulate HA biomineralization.HA/PTMC-F127-PTMC nanoparticles with uniform morphology were successfully synthesized through tuning the reaction parameters.PTMC-F12 7-PTMC nanoparticles were then directly dispersed in solution to form uniform mixture that was transformed into HA/PTMC-F127-PTMC composite scaffold after freeze-drying process.Unlike PTMC-F 127-PTMC scaffolds reported previously,the present composite scaffolds not only possessed higher HA content,but also achieved uniform distribution of HA nanoparticles at nanoscale,which provided better microenvironment for bone regeneration.The in vitro cell culture results suggested the critical role of the content and dispersion of HA nanoparticles in affecting stem cell behaviors.The improved distribution of HA nanoparticles at nanoscale significantly promote the growth and osteogenic differentiation of the mesenchymal stem cells(MSCs).Hydroxyapatite(HA)is the main mineral constituent of natural bone and has been used as a material for bone tissue engineering due to its biocompatibility,osteoconductivity and osteoconductivity.However,some effective ways in controlling the particle uniformity are still required for effective applications of HA in bone tissue regeneration.The HA/PTMC-F127-PTMC nanoparticles were also used as nanocarriers to delivery osteogenic growth factor(Bone morphogenetic protein-2,BMP-2).The loading efficiency of the BMP-2 on the nanoparticles was satisfied.The BMP-2 could be gradually released from the nanoparticles over a period without burst release.The BMSCs showed good proliferation and osteogenic differentiation on the BMP-2-loaded nanoparticles,significantly better than that on BMP-2-loaded pure PTMC-F127-PTMC or gelatin sponge reported previously.Then,a composite scaffold system that had homogeneous distribution of HA nanoparticles and controlled BMP-2 delivery was fabricated to design improved microenvironment for bone formation.The composite scaffolds exhibited preferred ability to induce BMSCs differentiation toward osteoblasts,which was confirmed by in vivo animal study.In conclusion,uniform PTMC-F127-PTMC nanoparticles as biotemplates were used to regulate HA biomineralization for optimizing the fabrication of HA/PTMC-F127-PTMC composite scaffolds for bone regeneration,and designing BMP-2 carriers with improved loading and releasing capacity,which would provide valuable information for novel scaffold fabrication for bone repair.