[Repair of radial segmental bone defects by combined angiopoietin 1 gene transfected bone marrow mesenchymal stem cells and platelet-rich plasma tissue engineered bone in rabbits].

OBJECTIVE

To investigate the osteogenesis effects of angiopoietin 1 (Ang-1) gene transfected bone marrow mesenchymal stem cells (BMSCs) seeded on beta tricalcium phosphate (beta-TCP) scaffolds (tissue engineered bone) with platelet-rich plasma (PRP).

METHODS

BMSCs were isolated from bone marrow tissue of rabbits. The Ang-1 gene was transfected into the BMSCs at passage 2 by lentivector, which were seeded on beta-TCP scaffolds with PRP (0.5 mL) after 48 hours of transfection. Bilateral radial segmental bone defects (15 mm in length) were created in 20 3-month-old New Zealand rabbits. Then the tissue engineered bone with the Ang-1 gene transfected BMSCs (experimental group) and untransfected BMSCs (control group) were implanted into the defects in the right and left radius, respectively. X-ray, histology, immunohistochemistry, and biomechanics observations were done at 2, 4, 8, and 12 weeks after operation.

RESULTS

In vitro, the transfected rate was over 90% and RT-PCR showed that the Ang-1 expression were significantly increased after transfection. The X-ray films showed that some callus formed at 4 weeks, partial bony union was observed at 8 weeks, and complete union at 12 weeks in experimental group; and bone union was not observed at 12 weeks in control group. HE staining showed that capillary appeared at 8 weeks and more capillaries were observed in new bone at 12 weeks in experimental group; only a few capillaries were observed at 12 weeks in control group. At 8 and 12 weeks, the microvascular density were (50.1 +/- 7.8) /mm2 and (66.1 +/- 3.5)/mm2 in experimental group and were 0 and (30.3 +/- 7.2)/mm2 in control group, showing significant differences between 2 groups at 12 weeks (Z = -2.107, P = 0.031). Immunohistochemistry examination showed that the positive cells can be found at 8 weeks in experimental group. And the biomechanical analysis showed that maximum loads of experimental group were significantly higher than those of control group in three-point bending test and compression test at 12 weeks (P < 0.05).

CONCLUSION

The tissue engineered bone with PRP and Ang-1 can increase the osteogenic properties by enhancing capillary regeneration, thus it can be used to repair radial segmental bone defects of rabbit.