Tissue Engineering Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (6B3), 9000 Ghent, Belgium.
Biomaterials. 2013 Jan;34(4):1004-17. doi: 10.1016/j.biomaterials.2012.10.051. Epub 2012 Nov 10.
Modular tissue engineering (TE) is a promising alternative to overcome the limits in traditional TE. In the present study, adipose tissue derived stem cells (ADSC)-laden microcarriers are used as building blocks (microtissues) that self-assemble into macrotissues in a bottom-up approach. These bone grafts were compared with a classical top-down approach (scaffolds). This concept was compared with bone marrow derived stem cells (BMSC) as cell source. Cells were immunophenotypically analyzed, followed by 2D/3D osteogenic differentiation in static/dynamic conditions. The bone graft quality was evaluated by (immuno)histochemistry and gene expression. After 6 weeks of dynamic culturing, scaffolds were highly colonized although not in the center and the osteogenic gene expression was higher in contrast to static cultures. A cell-to-microcarrier ratio of 5 × 10(6) cells-0.09 g microcarriers leaded to aggregate formation resulting in microtissues with subsequent macrotissue formation. ADSC/BMSC on scaffolds showed a downregulation of Runx2 and collagen I, demonstrating the end-stage, in contrary to microcarriers, where an upregulation of Runx2, collagen I together with BSP and osteocalcin was observed. This paper showed that high quality bone grafts (2 cm³) can be engineered in a bottom-up approach with cell-laden microcarriers.
模块化组织工程（TE）是克服传统 TE 局限性的一种很有前途的替代方法。在本研究中，脂肪组织来源的干细胞（ADSC）负载的微载体被用作自组装成宏观组织的构建块（微组织），采用自下而上的方法。这些骨移植物与经典的自上而下的方法（支架）进行了比较。该概念与骨髓来源的干细胞（BMSC）作为细胞来源进行了比较。对细胞进行免疫表型分析，然后在静态/动态条件下进行二维/三维成骨分化。通过（免疫）组织化学和基因表达评估移植物的质量。在动态培养 6 周后，支架虽然不在中心位置，但仍被大量定植，与静态培养相比，成骨基因表达更高。细胞与微载体的比例为 5×10(6)细胞-0.09 克微载体导致聚集形成，从而形成具有随后的宏观组织形成的微组织。支架上的 ADSC/BMSC 表现出 Runx2 和胶原蛋白 I 的下调，表明达到终末阶段，与微载体相反，微载体中观察到 Runx2、胶原蛋白 I 以及 BSP 和骨钙素的上调。本文表明，通过负载细胞的微载体的自下而上方法可以工程化高质量的骨移植物（2cm³）。
