简介: |
Biomaterials can play central role in biomedical engineering and regenerative medicine by facilitating cellular behavior and function, such as those where extracellular matrix (ECM) can facilitate embryonic stem (ES) cell growth, proliferation and differentiation. Both biologically derived and synthetic materials have been explored as an ECM in regenerative medicine and tissue engineering. However, complexities associated with natural materials, including complex structural composition, purification, immunogenicity and pathogen transmission have driven the development of synthetic biomaterials for use as 2D or 3D extracellular microenvironments. Moreover, the natural ECMs generate a complex environment and can place considerable stress on the differentiating cells during ES cell culture. The designing of artificial ECM should enable more efficient and scalable culture of ES cells, as well as greater control over material properties and tissue responses. It is expected that development of a new recombinant ECM using chimera proteins for tissue engineering and regenerative medicine will play a significant role in providing an alternative to organ or tissue transplantation.
Here, we summarizes some of the most recent developments on the construction of novel ECM using chimera proteins of adhesion molecules (e.g., E-cadherin and N-cadherin) or growth factors such as leukocyte inhibitory factor, LIF, epidermal growth factor, EGF and hepatocyte growth factor, HGF for ES cell proliferation and differentiation. To construct these chimera proteins, we fused functional domains of adhesion molecules and growth factors to IgG-Fc region (abbreviated as E-cad-Fc, N-cad-Fc, LIF-Fc, and EGF-Fc).
Until recently few successes have been reported on proliferation of ES cells in single cell cultures with homogeneous environment. Here, we showed that mouse ES cells cultured on E-cad-Fc coated surface had unique single cell morphology, higher proliferative ability and transfection efficiency than those grown under conventional conditions (Fig. 1). Furthermore, they require less LIF, probably due to the homogeneous exposure of cell to this cytokine.
The biological signals of growth factors and cytokines are mediated by two different forms, the secreted form and the cell membrane- or matrix-anchored form, which release different signal transduction cascades. As growth factors are required in only very tiny quantities to elicit biological response, designing artificial matrices for controlled growth factor presentation is necessary. We showed that immobilized LIF and E-cadherin can maintain ES cells efficiently with lower dependency of ES cells on LIF (Fig. 1). In addition to ES cell proliferation, E-cad-Fc and N-cad-Fc immobilized ECM can be used to induce controlled and efficient hepatic and neural differentiation at a single cell level.
Here, we report that recombinant E-cadherin substratum can guide the stepwise differentiation of ES cells to cells with characteristics of definitive endoderm, hepatic progenitor cells, and finally cells with phenotypic and functional characteristics of hepatocytes under homogeneous culture condition. Moreover, we established a second artificial substratum, N-cad-Fc, for controlling the neural differentiation. We stated that N-caherin can significantly enhance neurite outgrowth in ES/iPS cell-derived neural cells. Finally, the synergistic application of E-cadherin and N-cadherin for extracellular substratum is sufficient to induce homogeneous and complete neural conversion of ES/iPS cells in presence of specific soluble factors.
CV
Toshihiro Akaike was ｂorn on July 20, 1946 in Fuji-shi in Shizuoka Prefecture. He graduated from the Department of Synthetic Chemistry, Faculty of Engineering, University of Tokyo in 1969; obtained doctorate of synthetic chemistry at the University of Tokyo School of Engineering in 1975. In 1975, he joined the Heart Institute of Japan, Tokyo Women's Medical University as research fellow to professor Y. Sakurai and was involved in research on biomaterials science such as biomedical polymers and antithrombogenic materials. In 1980, he was appointed associate professor of the Faculty of Engineering, Tokyo University of Agriculture and Engineering, with research focus on cell-specific recognition materials for cell culture and separation and bio-artificial liver. In 1990, he became professor at joined the Tokyo Institute of Technology School of Bioscience and Biotechnology, embarking on bio-artificial liver research; applications of glycotechnology to cell-specific recognition materials; molecular biological analysis of hepatic cell adhesion, proliferation, and apoptosis (hepatitis); and applications of the results to diagnosis and therapy. Between 1989 and 1995, he also served as Laboratory 3 Director of the Kanagawa Academy of Science and Technology, and was in charge of the “Akaike Highly Functional Molecular Recognition Project,” studying the application of cell-specific recognition materials to hybrid organs, missile drugs, and liver-tissue engineering. From 1999-2012, he served as Professor of Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology. He focused on synthetically and genetically-engineered cellular matricies such as sugar-carrying synthetic polymers and chimeric proteins of various cadherins and citekines and applied them for tissue engineering and regenerative medicine. Since April 2012 he is Professor emeritus of Tokyo Institute of Technology and Professor of Donated Chair of Biomaterials Design for Regenerative Engineering.
Areas of specialties include design of synthetic polymers and proteins for cell-specific recognition, hybrid artificial organs (liver, blood-vessel, heart, nerve, pancreas), drug (gene) delivery systems, cell engineering, tissue engineering, and regenerative medicine.
Books written include (among others): Biofunctional Material Science: Basics of Artificial Organs, Tissue Engineering, and Regenerative Medicine (Biotechnology Textbook Series #12, published by Corona Publishing Co., Ltd. in 2006), and Bioengineering for Regenerative Medicine (Regenerative Medicine Basic Series, published by Corona Publishing Co., Ltd. in 2007), Invitation to Biomaterials World (Technonet Publishing Co., Ltd, in 2008)
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