胶原/羟基磷灰石复合支架负载软骨细胞构建组织工程软骨

背景:新型复合软骨组织工程支架克服了传统支架的诸多不足,如组织相容性差、生物力学性能不足、降解过快、材料单一、难与关节软骨的分层结构相匹配等,为软骨组织工程的发展提供新的途径。目的:观察具有柱状分层结构的胶原/羟基磷灰石复合支架对软骨细胞的吸附作用,以及对软骨细胞生物学性状的影响,评价其作为软骨组织工程支架的可行性与价值。设计:开放性实验。单位:中山大学附属第三医院骨科,华南理工大学材料学院。材料:实验于2004-06/11在中山大学附属第三医院动物实验中心完成。选取2周龄普通级健康新西兰白兔1只,雄性,饲养环境温度20℃,湿度40%。方法:①在羟基磷灰石中加入少量的去离子水,分散后加入I型胶原溶液搅拌复合,并按一定比例加入碳二亚氨,调配形成不同比例的胶原/羟基磷灰石复合物,并逐层加入模具,最上层采用纯胶原,底层为纯羟基磷灰石。将制备好的柱状分层的胶原/羟基磷灰石复合材料冷冻干燥后,经环氧乙烷气体消毒后备用。②体外培养幼兔关节软骨细胞并扩增,吸附于多孔胶原/羟基磷灰石复合支架上三维立体培养,通过相差倒置显微镜、组织学、扫描电镜及免疫组织化学检测支架对软骨细胞的表型、增殖及功能的影响。主要观察指标:①胶原/羟基磷灰石多孔支架的形貌观察。②体外培养的软骨细胞生物学性状观察。③胶原/羟基磷灰石多孔支架材料与软骨细胞相容性的观察。结果:①胶原/羟基磷灰石多孔支架的形貌观察:胶原/羟基磷灰石为具有一定力学强度的柱状分层的三维多孔支架,最上层为纯胶原,底层为纯羟基磷灰石,中间为胶原与羟基磷灰石复合。扫描电镜可见支架内具有不规则的通孔结构,孔径较均匀,相互连通,平均孔径约为147μm。②体外培养的软骨细胞生物学性状观察:刚分离的软骨细胞为球形,活细胞率达95%。24h后细胞开始贴壁,逐渐伸展为三角或多角形,内含分泌颗粒。细胞保持单层生长,传代后增殖速度加快,4d铺满培养瓶。随着传代次数的增加,增殖速度开始减慢,当传到第6代时,细胞分裂能力明显下降,细胞变形明显,体积变大,梭形为主,边沿模糊,折光性弱,表现出细胞老化和向成纤维细胞反分化的趋势。③胶原/羟基磷灰石多孔支架材料与软骨细胞相容性的观察:多孔胶原/羟基磷灰石复合支架亲水性好,软骨细胞吸附于支架表面,增殖并逐渐顺孔隙迁徙至支架内部,在孔壁贴附良好,表型维持稳定,分泌胞外基质。结论:柱状分层结构的胶原/羟基磷灰石复合支架具有良好的细胞相容性,较单纯胶原力学性能更强,是比较理想的软骨组织工程支架材料。

Construction of tissue engineering cartilage with collagen/hydroxyapatite composite scaffolds loaded chondrocytes in vitro

BACKGROUND: A new composite scaffold for cartilage tissue engineer ing has been employed to culture chondrocytes and overcome many limits related to traditional scaffolds, such as poor biocompatibility, inferior mechanical property, inappropriate biodegradability, and simplex structure which can not match layered structure of articular cartilage, etc. The new composite scaffolds provided a new approach for the research of cartilage tissue engineering.OBJECTIVE: To evaluate the feasibility and value of layered cylindrical collagen/hydroxyapatite (HA) composite for cartilage tissue engineering by observing how it absorbs chondrocytes and affects its cellular characteristics.DESIGN: Completely randomized design and controlled experimental study.SETTING: Department of Orthopaedics, Third Hospital Affiliated to Sun Yat-sen University, and College of Material Science, South China University of Technology.MATERIALS: The experiment was conducted at the central experimental laboratory of the Third Hospital Affiliated to Sun Yat-sen University from June to November 2004. One two-week-old male healthy New Zealand rabbit,which was bred in 20 ℃ and 40% humidity, was used in this experiment.METHODS: ①Right amount of deionized water was added into HA, collagen I solution was added to disperse HA, then carbodiimide was added in the mixture at a proportion for getting the collagen/HA composite at different ratios. Pour to the certain mould in successive layers. The upper layer was pure collagen and the bottom was pure HA. The prepared layered cylindrical collagen/HA composite was put into the ultra low temperature freezer, lyophilized, and sterilized by ethylene oxide for the following procedures. ② Chondrocytes of juvenal rabbit were isolated and multiplied in vitro, then chondrocytes were seeded onto porous collagen/HA composite scaffold and cultured. The effects of composite scaffold on chondrocytes'morphological changes, proliferation, and function were evaluated through a series of examinations such as inverted phase-contrast microscopy, histological, scanning electron microscopy and immunohistochemistry.MAIN OUTCOME MEASURES: ①Morphology of collagen/HA porousscaffold. ②The characteristics of chondrocytes cultured in vitro. ③ The chondrocytes' compatibility with the collagen/HA porous scaffold.RESULTS: ①Morphology of collagen/HA porous scaffold: Collagen/ HA was a cylindrical three-dimensional porous scaffold in layer structure with certain mechanical strength. The top layer was pure collagen, the bottom was pure HA, and the intermediate layer was collagen and HA composite.Under scanning electron microscope, the scaffold had irregular blowhole structure, the apertures were even and pores were communicated each other. The average pore diameter was about 147 μm. ②The characteristics of chondrocytes cultured in vitro: The chodrocytes that had just been isolated were spherical; rate of living cells was 95%. 24 hours later, the cells were going to attach to the wall, extend to be triangle or polygon. The cytoplasms were abundant with secretary granules inside. The cells kept on growing in monolayer and the multiply rate accelerated after passage, and chondrocytes overspreaded the culture flask in 4 days. After passaged for several times, the multiply rate decreased. In passage Ⅵ, the ability of cell division was decreased obviously, the cytomorphosis was clear. Cellular sizes were larger. Most of cells were shuttle-shape, less refracted with blur edges, which trended to age and dedifferentiate to fibroblast. ③The chondrocytes' compatibility with the collagen/HA porous scaffold: Cylindrical collagen/ HA composite scaffold in layer structure had good hydrophilicity. The chondrocytes adhered to the surface of the scaffold, proliferated and migrated toward the scaffold through the pore. Chondrocytes attached to wall of microholes of the scaffold had largely maintained a rounded morphology and could secrete the extracellular matrix on the porous scaffold.CONCLUSION: Cylindrical collagen/ HA composite scaffold in layer structure has good cellular compatibility.It is stronger in mechanical property than pure collagen, is anideal scaffold for cartilage tissue engineering.