Construction of tissue engineering bone as well as radiological appraisal in the repair of standard sheep metatarsus bone defect

Yuerong ZHOU; Zhanghua LI; Zhenhua SONG; Qiang ZHAO; Changyong WANG

ABSTRACT

BACKGROUND:

Bone marrow derived mesenchymal stem cells (BMMSCs) have multi-differentiation potentials, possessing a repairing capability for the sectional bone defects if combined with degradable porous β-tricalcium phosphate china. This provides a new idea in clinical repair of various bone defects.

OBJECTIVE:

To explore in radiology the curative effect of implanting porous β-tricalcium phosphate and autogenous BMMSCs compound to treat bone defects.

DESIGN:

A randomized controlled study with callus growth at various healing periods as subjects for observation.

SETTING:

Department of Orthopaedics, Renmin Hospital, Wuhan University; Tissue Engineering Center, Research Institute of Basic Medicine,Academy of Military Medical Sciences of Chinese PLAMATERIALS This experiment was carried out at the Tissue Engineering Center, Research Institute of Basic Medicine, Academy of Military Medical Sciences of Chinese PLA between March and September 2002. Twenty China healthy adult sheep were randomized into the groups of blank control group (4 sheep), simple implantation group (8 sheep) and complex implantation group (8 sheep).

METHODS:

Under general anesthesia and aseptic condition, 10-15 mL of sheep marrow was extracted; MSCs were separated and cultured before combined with porous β-tricalcium phosphate china for tissue engineering bone construction. Rats in each group were cut off 21mm long metatarsus in the middle section of metatarsus bonestem. Β-tricalcium phosphate china and autogenous MSC compound was implanted into the sheep of the complex implantation group; β-tricalcium phosphate china was implanted into the simple implantation group; and the bone defects in the blank control group remained untouched. Then the incision was sutured.X-ray filming was carried out right after the operation, as well as 1, 3,and 6 months after the operation for radiological appraisal (scored for1 if bone union formed in one surface of bone defect, but scored 0 if no boneunion formed in any surface of bone defect, and scored 4 if bone union formed in front, back, lateral surfaces and the center of bone defect), Xray radiation-resisting density was analyzed to compare the results of bone defect repair.MAIN OUTCOME

MEASURES:

The postoperative general condition and general observation, as well as the results of the radiological analysis of the bone defects of all sheep.

RESULTS:

Totally 20 sheep were brought into this xperiment and all entered the stage of result analysis. ① The postoperative general conditionSheep regained consciousness 2-6 hours after the operation without incision infection and loosing of internal fixation. Their spirit gradually was back to normal 1 week after the operation, at which time the injured legs could touch ground but were incapable of bearing load, and the affected legs could bear load 2 weeks after the operation, walked slightly lamely 3 weeks after the operation, and even moved freely without limp 4 weeks after the operation. ②The general condition 6 months after the operation In pure implantation group, the surface white hyaline cartilage-like tissues were gradually calcified, with both ends connected with the host bone by bone bridge, but china granules could still be easily observed; while no implantation substance could be observed in compound implantation group,with the boundary between implantation substance and host bone vanished,and bone defect became basically the same as host bone. However there was no bone tissue formed in bone defect at various postoperative time points in the blank control group. ③ Radiological analysis of the bone defects at various postoperative time points The radiological rating score was obviously higher in complex implantation group at the time poin ts of 3, 6 months after the operation compared with the pure implantation group [(2.3±0.3), (1.8±0.5); (3.3±0.5), (2.6±0.6), P ＜ 0.05]. ④ Radiological analysis of bone callus thickness and the relative value of radiation-resisting density at various postoperative time points The bone callus thickness in the complex implantation group was obviously lower than that of the pure implantation group at the postoperative time point of 6 months (4.62 vs 7.64, P ＜ 0.05), with relative value of radiation-resisting density obviously higher than that of the pure implantation group (70.4±1.5 vs 61.18±1.2, P ＜ 0.05).

CONCLUSION:

Radiological appraisal and bone defect density measurement can well reflect the dynamical repairing process of bone defects; the implantation of porous β-tricalcium phosphate china and autogenous BMMSCs compound into sheep can enhance the repair of large sectional bone defect.