Experimental Study On Bone Marrow Mesenchymal Stem Cells Combined With Silk Fibroin In Vitro And Vivo

Objective Through observing the impact of pore size of silk fibron(SF) on the growth and proliferation of bone marrow mesenchymal stem cells(BMSCs) in vitro, and on repairing of bone defects in vivo, elementarily assess its suitable pore size in bone tissue engineering, and the clinical significance of SF that serve as one extracellular matrix material. Methods We established the model of cultivation and proliferation of BMSCs in vitro, and collected affluent cells to seed in three different pore size of porous SF which were SF-I (SF with 58μm pore size), SF- II (SF with 78μm pore size) and SF-III(SF with 111μm pore size) in vitro. Then we carried out two parts of experiments. In part one, we continuously cultured the BMSCs/SF composite in vitro, in part two, transplanted the composite in vivo to cure 15mm long metaphyseal radius defects of 24 New Zealand white rabbits of which 8 defects (group A) were treated with BMSCs/SF- I composites, 8(group B) were treated with BMSCs/SF- II, and the other 8 rabbits(group C) were implanted with BMSCs/SF-III. A series of examinations including radiograph, histomorphology, invert microscope, scanning electron microscope(SEM) and laser scan confocal microscope(LSCM) were carried out to analyze the experimental phenomenon. Results We had successfully established the model of BMSCs'cultivation and proliferation in vitro. In part one, BMSCs were able to grow with normal morphon and vigor in all three pore sizes of materials in vitro, and cells performed the best capability of growth and proliferation in SF-III. In part two, different quantity of new bone formed, and defects were partly or completely repaired in three groups, BMSCs/SF- II composite produced the most desired effects. In all experiments no reactions of toxicity and immunity were found. Conclusion The pore size of silk fibron decides the growth behavior of BMSCs in vitro and bone regeneration in vivo, silk fibron with 78μm and more than 78μm pore size are more suitable for cells' and bone tissue's ingrowth. Silk fibron served as extracellular matrix material in bone tissue engineering has great advantage in biocompatibility, cellular adhesion and degradability in vivo. Silk fibroin is one prospective biomaterial.