| Objective The objective of this study was to investigate whether autogenous marrowstromal cells（MSCs）could augment healing of the tendon graft-to-bone interface afteranterior cruciate ligament (ACL) reconstruction.Methods The autogenous MSCs of peripheral blood were isolated and cultured invitro，which was mobilized by the granulocyte colony-stimulating factor. Forty-eightimmature New Zealand white rabbits were utilized and randomly divided into threegroups. For the group A,they underwent anterior cruciate ligament reconstructions inthe left knee with a long digital extensor tendon graft secured by suspensory fixationtechnique and injected with a mixture of MSCs and fibrin glue.Once the graft had been properly positioned in the tunnel, they were fixed using the same procedure in the groupB and C. For the group B, instead of MSCs, fibrin glue was injected into the tendongraft that would sit inside the tunnel. For the group C, the left limb underwent a similaroperation with neither the MSCs nor fibrin glue injecting in the tunnel.Three specimensfrom each group were harvested at2weeks,4weeks,8weeks and12weekspostoperatively and evaluated by conventional histological and immunohistochemicalmethods which include hematoxylin and eosin, toluidine blue and modified trichromestaining. The number of fibroblasts was counted in tendon-bone interface ofpostoperation with HE staining. And we obtained the histology score of Buark in groupA and group B specimens.All of that was in order to ask for the tendon-bone healinginformation.Results (1)①Thethree specimens produced different histological findings at theinterface between the tendon and bone. Histological examination showed that,on thegroup A, loose connective tissue and a few fibroblasts were noted around thetendon-bone interface at two weeks after the operation. At the same time point,theinterface was still distinct.At4weeks, a large number of loose connective tissue andfibroblasts were noted.There were a few chondrocyte-like cells and collagen fibers. Theinterface can not be noted. Newly formed bone was apeared. At8weeks,there werelarge areas of chondrocyte-like cells and collagen fibers between tendon and bone.Sharpey fiber appeared in bundle shape. In the tendon-bone interface,dense connectivetissue was formed at12weeks after the operation. A lot of regular Sharpey fiber andfibrocartilage was found.The calcified cartilage appeared in the tendon-bone interface.②At2weeks,fibrovascular interface filled the tunnel between tendon and bone ingroups B and C. The interface was still distinct. A few fibroblasts can be observed butthere were no collagen fibers. At4weeks, a few loose connective tissue and newlyformed bone were observed around the tendon-bone interface. There were only a few chondrocyte-like cells and collagen fibers. Perpendicular collagen fibers were notobserved crossing this zone at the same time point. There were more chondrocyte-likecells and collagen fibers at8weeks after the operation. Occasional perpendicularcollagen fibers were observed crossing this zone.At12weeks, large areas ofdisorganised chondrocyte-like cells and iregular Sharpey fiber were noted.(2) At highmagnification microscope,the number of fibroblasts were counted in tendon-boneinterface of postoperation with HE staining.We adopt one-way ANOVA and SNK testto analyse the data.The comparison between group A*and group B**and C***wereconsidered significant（P＜0.05）.On the contrary, the comparison between groupB**and group C***were considered non-significant.(3) Based on the evaluation offibrovascular tissues and Sharpey fiber on the tendon-bone interface, The data ofhistomorphology Buark score were analysed by Wilcoxon rank sum test.In group A andgroup B,the two medians of histology Buark score were signifcantly differen（tP＜0.01）.It was concluded that the histology Buark score of group A was more than the group Bspecimens.Conclusion Based on the histological findings, the present study demonstrated thatthe autogenous MSCs filling on top of the femur tunnel can improve the insertionhealing of tendon-bone in a rabbit model through formation of fibrocartilagenousattachment at early time points. |
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