Biodegradation of a novel bionic scaffold with nanostructurein vivo**

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Abstract

BACKGROUND:

Bone implant materials have been previously reported to be not coincident between inducing velocity of new bone formation and degradation velocity itself; therefore, the materials could not be completely degraded but formed into foreign substances. A novel artificial bone implant material, characterizing by well biocompatibility, biodegradation, and biomechanics, is focused in biomaterials field recently.

OBJECTIVE:

To study the biodegradation of a novel bionic scaffold with nanostructure, i.e., poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/sol gel bioactive glass (PHBV/SGBG), in vivo.

DESIGN, TIME AND SETTING:

A controlled animal experiment was performed at Animal Experimental Center of the Third Hospital affiliated to Sun Yat-sen University from May 2005 to October 2006.

MATERIALS:

PHBV/SGBG was provided by Materials Institute of South China University of Technology, and ethylene oxide was sterilized for preparation.

METHODS:

Eight hybrid dogs were used to make models of tibia diaphyseal defect, having two defects on both left and right sides. The tibia diaphyseal defects at proximal part were considered as the control group, and those were not performed with any treatment; while, the tibia diaphyseal defects at distal part were considered as the experimental group, and PHBV/SGBG was fully implanted into the defect regions. Every two dogs were sacrificed at different time points of 2, 4, 8, and 12 weeks, respectively.

MAIN OUTCOME MEASURES:

In vivo biodegradation and osteogenesis were monitored under optic microscopy and electron microscope.

RESULTS:

The PHBV/SGBG scaffold had well biodegradation and rapid degradation velocity, and it began to degrade at two weeks after operation. The PHBV/SGBG scaffold was almost replaced by new bone tissues at 8 weeks after operation and completely degraded at 12 weeks after operation. In addition, the PHBV/SGBG scaffold had a good ability to induce new bone formation from edge to center. Whereas, surface depression in the defect region was still visible in the control group, cortical bone was not formed in embedded region of soft tissue; furthermore, electron microscopy demonstrated that calcium salt deposition was increased in the bone defect region, and the structure was tight; however, the defect was not completely repaired, and some voids were still visualized.

CONCLUSION:

The novel bionic scaffold, PHBV/SGBG, degrades fast in vivo to generate new bone tissues. The new bone regenerate accompanied by a fitting degradation of the novel bionic scaffold that achieve complete repair.

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