Effects of Three-Dimensional Culture of Mouse Calvaria-Derived Osteoblastic Cells in a Collagen Gel with a Multichannel Structure on the Morphogenesis Behaviors of Engineered Bone Tissues

Bone has a complex hierarchical structure that contributes to its superior mechanical properties. Therefore, reproducing the complex hierarchical structure of bone tissue is a promising strategy to construct functional engineered bone tissues. In this study, we aimed to reproduce this complex hierarchical structure by developing a method for the three-dimensional culture of MC3T3-E1 osteoblastic cells in a collagen gel with a multichannel structure (MCCG), which mimics the parallel arrangement of Haversian canals in bone tissue. MCCG was homogeneously calcified via the biomineralization properties of MC3T3-E1s. Confocal laser scanning microscopy revealed that MCCG could support the growth and proliferation of MC3T3-E1 cells in the deeper parts of the engineered bone tissue and that the cells formed a toroidal structure on the channel surface and a network-like structure in the gel matrix region. Furthermore, quasi-quantitative measurement of osteocalcin and dentin matrix protein 1 expression indicated the coexistence of two types of cells with different morphologies and differentiation phenotypes. Thus, three-dimensional culture of MC3T3-E1 cells in MCCG yielded engineered tissues mimicking the hierarchical structures of bone tissues. Engineered bone tissues with a biomimetic hierarchical structure could be used as a model system for investigating bone metabolism and evaluating the efficacy of novel drugs

Application of Multichannel Collagen Gels in Construction of Epithelial Lumen-like Engineered Tissues

Introduction of epithelial lumen-like structures such as blood and lymphatic vessels, as well as renal tubules, is a prerequisite for successful construction and function of artificially engineered giant tissues. Here, we demonstrate a methodology for construction of various epithelial lumen-like structures by using multichannel collagen gels (MCCGs). MCCGs were prepared and used as template scaffolds for constructing epithelial lumen structures in a controlled fashion. The effect of NaCl concentration on the multichannel structure of MCCGs was investigated by using confocal laser scanning microscopy along with fluorescent staining. The channel diameter increased with increasing NaCl concentrations in the collagen solution and the phosphate buffer solution. In contrast, the channel number decreased with increasing NaCl concentrations. Engineered tissues with various lumen-like structures were constructed by seeding and culturing Madin–Darby canine kidney cells on MCCGs. The diameter of the lumen and the number of lumens per unit area were controllable by regulating the multichannel structure of cylindrical MCCG. We believe that our methodology for the construction of engineered tissues possessing epithelial lumen-like structures will prove helpful in regeneration of giant tissues with various hierarchical structures

Application of Multichannel Collagen Gels in Construction of Epithelial Lumen-like Engineered Tissues

Introduction of epithelial lumen-like structures such as blood and lymphatic vessels, as well as renal tubules, is a prerequisite for successful construction and function of artificially engineered giant tissues. Here, we demonstrate a methodology for construction of various epithelial lumen-like structures by using multichannel collagen gels (MCCGs). MCCGs were prepared and used as template scaffolds for constructing epithelial lumen structures in a controlled fashion. The effect of NaCl concentration on the multichannel structure of MCCGs was investigated by using confocal laser scanning microscopy along with fluorescent staining. The channel diameter increased with increasing NaCl concentrations in the collagen solution and the phosphate buffer solution. In contrast, the channel number decreased with increasing NaCl concentrations. Engineered tissues with various lumen-like structures were constructed by seeding and culturing Madin–Darby canine kidney cells on MCCGs. The diameter of the lumen and the number of lumens per unit area were controllable by regulating the multichannel structure of cylindrical MCCG. We believe that our methodology for the construction of engineered tissues possessing epithelial lumen-like structures will prove helpful in regeneration of giant tissues with various hierarchical structures