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ABSTRACT: Hamstring tendons are a commonly used substitute for anterior cruciate ligament (ACL) reconstruction. Ligaments and tendons are similar in composition but the ACL is more complex than hamstring tendons in function and gross morphology, which are highly dependent on its structure and ultrastructure. The purpose of this study was to compare the morphology and ultrastructure of normal human ACL and hamstring tendons, including the cell type and arrangement, expression level of proteoglycans, diameter, and density of collagen fibrils. Twenty semitendinosus or gracilis tendons and 20 ACL specimens were harvested from patients with ACL rupture or osteoarthritis undergoing routine total knee arthroplasty. The specimens were examined histologically and the ultrastructure was observed using scanning and transmission electron microscopy. Semitendinosus and gracilis tendons showed a homogeneous arrangement of collagen fibers and cell type. They had lower fibril density and more widely distributed fibril diameters. In the ACL, there was a more complex arrangement of collagen fibers, distribution of proteoglycans and different cell types. Electronic microscopy demonstrated a combination of parallel, helical and nonlinear networks of ACL fibrils, and fibril diameters were smaller and more nonuniform. This study compared the anatomy of normal human ACL and hamstring tendons, which may provide a standard for evaluating hamstring tendons grafts after ACL reconstruction and may facilitate the application of hamstring tendons in clinical applications.
The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology 07/2012; 295(9):1430-6. · 1.47 Impact Factor
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ABSTRACT: Ceramic-derived materials have shown enhanced osteogenic potential for bone tissue engineering applications. Silica is the major component of bioglass, and titania, the oxide complex of titanium, has been found to enhance osteoblast differentiation. In this study, three groups of sol-gel-derived silica-titania fibrous meshes with precursor ratios of Ti:Si = 7:3, 1:1, 3:7 were fabricated by electrospinning. The effects of silica content on the crystal phase and morphology of silica-titania hybrid nanofiber meshes were also analyzed by scanning electron microscopy, X-ray diffraction, and laser confocal microscopy. The osteogenic potential of the silica-titania meshes was evaluated by seeding mesenchymal stem cells (MSCs) on each mesh and determining cell number, osteodifferentiation markers, and osteopontin production over time. Our results show that cells proliferated throughout the mesh surfaces with similar morphology in all groups. Decreased cell proliferation was observed with the fiber meshes compared with glass controls, whereas cell differentiation toward osteoblast was enhanced on the mesh groups, especially on the Ti:Si = 7:3 group. These findings suggest that higher fiber diameter, degree of crystallization, and titania content of nanofibers can enhance osteodifferentiation of MSCs. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:3511-3517, 2012.
Journal of Biomedical Materials Research Part A 07/2012; 100(12):3511-7. · 2.63 Impact Factor
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ABSTRACT: Focal full-thickness articular cartilage defects are challenging to repair. The purpose of this study was to find a simple, effective 1-step articular cartilage repair method. Because stem cell niches produce a microenvironment for stem cell self-renewal, proliferation, and differentiation, we integrated in situ bone marrow stem cells with an implanted poly(L-lactic-co-glycolic acid) (PLLGA) scaffold. Marrow stem cells grew and proliferated on cell-free PLLGA scaffolds, which were evaluated by scanning electronic microscopy (SEM) and Cell Counting Kit-8 (Dojindo, Kumamoto, Japan). Twenty-seven rabbits (54 knees) with large cylinder femoral trochlear cartilage defects were created and repaired with microfracture and cell-free PLLGA scaffold implantation (group 1), microfracture (group 2), or cell-free PLLGA scaffold implantation (group 3).Outcomes were evaluated by magnetic resonance imaging, International Cartilage Repair Society scores, histology, and immunohistochemistry. The repair effects were better in group 1 than in groups 2 and 3. In group 1, hyaline-like cartilage formed at week 24. Magnetic resonance imaging showed homogeneous signals as the adjacent normal cartilage. Collagen type II and toluidine blue were stained positively as normal cartilage tissue, and the color and thickness of regenerated tissue were similar to surrounding normal tissue. The combination of microfracture and cell-free PLLGA scaffold implantation used endogenous marrow stem cells in situ and promoted hyaline-like cartilage regeneration rapidly and effectively.
Orthopedics 05/2012; 35(5):e665-71. · 2.66 Impact Factor
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Zhenxing Shao,
Xin Zhang,
Yanbin Pi,
Xiaokun Wang,
Zhuqing Jia, Jingxian Zhu,
Linghui Dai,
Wenqing Chen,
Ling Yin,
Haifeng Chen,
Chunyan Zhou,
Yingfang Ao
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ABSTRACT: Mesenchymal stem cell (MSC) is a promising cell source candidate in tissue engineering (TE) and regenerative medicine. However, the inability to target MSCs in tissues of interest with high efficiency and engraftment has become a significant barrier for MSC-based therapies. The mobilization and transfer of MSCs to defective/damaged sites in tissues or organs in vivo with high efficacy and efficiency has been a major concern. In the present study, we identified a peptide sequence (E7) with seven amino acids through phage display technology, which has a high specific affinity to bone marrow-derived MSCs. Subsequent analysis suggested that the peptide could efficiently interact specifically with MSCs without any species specificity. Thereafter, E7 was covalently conjugated onto polycaprolactone (PCL) electrospun meshes to construct an "MSC-homing device" for the recruitment of MSCs both in vitro and in vivo. The E7-conjugated PCL electrospun meshes were implanted into a cartilage defect site of rat knee joints, combined with a microfracture procedure to mobilize the endogenous MSCs. After 7 d of implantation, immunofluorescence staining showed that the cells grown into the E7-conjugated PCL electrospun meshes yielded a high positive rate for specific MSC surface markers (CD44, CD90, and CD105) compared with those in arginine-glycine-aspartic acid (RGD)-conjugated PCL electrospun meshes (63.67% vs. 3.03%; 59.37% vs. 2.98%; and 61.45% vs. 3.82%, respectively). Furthermore, the percentage of CD68 positive cells in the E7-conjugated PCL electrospun meshes was much lower than that in the RGD-conjugated PCL electrospun meshes (5.57% vs. 53.43%). This result indicates that E7-conjugated PCL electrospun meshes absorb much less inflammatory cells in vivo than RGD-conjugated PCL electrospun meshes. The results of the present study suggest that the identified E7 peptide sequence has a high specific affinity to MSCs. Covalently conjugating this peptide on the synthetic PCL mesh significantly enhanced the MSC recruitment of PCL in vivo. This method provides a wide range of potential applications in TE.
Biomaterials 04/2012; 33(12):3375-87. · 7.40 Impact Factor
