Experimental Study Of Rats Segmental Radial Defects Repaired With Tissue Engineering Method

Objective:To observe the curative effect of repairing segmental bone defects in rats with the composite grafts of purified,culture-expanded rat bone marrow mesenchymal stem cells(MSCs) and anti-extracted bovine cancellous bone(BCB).To provide experimental study for seeded cells and cellular scaffold′s choice in tissue engineering as well as clinical therapy of bone defect.Method:The Wistar rats were divided into three group randomly-test and control,blank.An bone defect(5mm in length) was created at two radii in each rat.The experimental groups were filled with BCB/MSCs.The control groups were placed with BCB,that had not been loaded with cells.The blank groups were left untreated(no BCB was implanted).The mesenchymal stem cells were isolated from rat bone marrow and grown,purified,expanded in culture,and then the MSCs were cultured in combination with BCB.The composite grafts were tested by scanning electron microscope.The curative effect was evaluated by radiographic examination, histologic analysis,biomechanical test at2,4,8,14,18 week after surgery. Result:Roentgenographically,The bone defects that had been treated with grafts exhibited new bone formation,increasing with time.But the result of experimental groups were apparently superior to the control groups′s at 2,4,8,14,18 week after operation.At the same time,The rate and quality of new bone formation was significantly different in the experimental and the control groups on histologic analysis.At 14 week the defects in experimental groups were basically healed with the appearance of marrow cavities.The mechanical strength of composite grafts reached almost to normal level at 18 week.The loads and bending-stresses of experimental groups were remarkably higher than those of the control groups.The defects in blank groups,no formation of new bone were found after operation and were finally repaired only by fibrous tissue.Conclusion: MSCs are capable of being purified,cultured,expanded in vitro and reaching effective osteoplastic density in vivo. MSCs are ideal seeded cells for bone tissue engineering.BCB/MSCs may be compoundedin culture,the composite grafts cause no obvious immune rejection after being transplanted into allogenic rats.BCB may be used as a alternative carrier for seeded cells.These studies demonstrate that the composite grafts more quickly promote the new bone formation.The result of experimental groups has an obviously advantage over the control groups′s.