Studies On Effects Of Biomineralization Capacity Of PLLA/gelatin Composite Fibers On Osteogenic Differentiation Of BMSCs

In considering the chemical compositions of natural bone tissue,organic-inorganic composite biomaterials are proper choices for bone regeneration by using the concept of tissue engineering.To mimic the network of natural collagen fibers,in this thesis,PLLA/gelatin composite fibers were electrospun.And to prepare organic-inorganic composite fibers,biomineralization on these PLLA/gelatin composite fibers was carried out.However,cell culture medium was used instead of simulated body fluids(SBF).There are two considerations to do so.On one hand,culture medium contains various ions,resembling the SBF.On the other hand,it is not clear to the present how biomineralization during cell culture will influence cell biological behaviors.Therefore,the bioresurgical studies were carried out by immersing PLLA/gelatin composite fibers in aMEM containing ?MEM or FBS containing ?MEM.To accelerate the mineral deposition,one group of PLLA/gelatin composite fibers was pre-treated with CaCl2 solution.Three major conclusions were drawn from these studies.Firstly,cell culture medium was indeed able to sedimentary minerals on PLLA/gelatin composite fibers.Secondly,the CaCl2 pre-treated fibers were able to induce mineral depositions faster and more abundant in comparison with the non-treated group.Thirdly,the presence of FBS was identified able to enhance biomineralization due to the possible adsorption of proteins onto fibers,which provided more nucleation sites for mineral depositions.Afterwards,the non-treated and CaCl2 pre-treated nanofibers were co-cultured with bone mesenchymal stromal cells(BMSCs)without using osteogenic inductive medium.Along with cell proliferation,mineral depositions on fibers were still able to be detected,moreover,more minerals could be seen on the CaCl2 pre-treated fibers.At the same time,osteogenic differentiation of BMSCs were monitored.It was found that the osteogenic differentiation of BMSCs was significantly promoted on the CaCl2 pre-treated fibers than those on non-treated fibers.This phenomenon revealed that the biomineralization capacity of scaffolding materials was a key factor in regulating the regeneration potential of bone defects.In other words,scaffolding materials having higher ability in inducing biomineralization would result in stronger ability in inducing osteogenic differentiation,which would apparently facilitate bone repairing.