1. Fundamentals of Multiscale Fabrication
Lecture 12
Applications IV:
Tissue Engineering
Kahp-Yang Suh
Associate Professor
SNU MAE

2. What is tissue engineering?

3. Regulation of cell and tissue functions by local ECM cues
Dynamic cell-matrix interactions in
Development
Cancer metastasis
Wound healing
Regeneration
Functioning of many cell types in health and disease states can be significantly affected by naturally occurring nanotopographic structures defined by the ECM.
Extracellular matrix

4. SEM of cultured mammalian cells

5. Elements of the Cytoskeleton
Eukaryotic cells contain these main kinds of cytoskeletal filaments
– Actin filaments (Microfilaments), Intermediate filaments and Microtubules.

6. Elements of the Cytoskeleton
Microfilaments are found around the periphery of the cell. They also form the contractile element of skeletal muscle
Microtubules are found in arrays radiating from the nucleus, in the spindle apparatus and in the basal bodies of cilia
Intermediate filaments are seen as cables stretching across the cell and in the nuclear lamina

7. Cell Adhesion
Cell adhesion is the binding of a cell to another cell (“cell-to-cell adhesion”) or to a surface or matrix (“cell-matrix adhesion”)
Cellular adhesion is regulated by specific adhesion molecules (“receptors”) that interact with molecules (“ligands” or “counter-receptors”) on the opposing cell or surface.
Cell adhesion generally involves protein molecules at the surface of cells, so the study of cell adhesion involves cell adhesion proteins and the molecules that they bind to.

8. Cell adhesion is highly regulated by many receptors and binding proteins
ECM protein: Collagens, Fibronectin, Laminins

9. Cell adhesion is highly regulated by many receptors and binding proteins
The basal lamina is a layer of extracellular matrix on which epithelium sits and which is secreted by the epithelial cells.
It is typically about nanometers thick. From Wikipedia.

11. Cell adhesion is highly regulated by many receptors and binding proteins

12. Immuno-staining of adhesion receptors and cytoskeletal structures

13. Cell-ECM nanotopography interactions
Fibroblasts in 3D
Collagen fibers
Basement membrane
500 nm
2D flat, rigid surface
Cell Tissue Res. 299, 39-46
Better understanding of how the cell behavior changes when cells are placed in a more bio-mimetic microenvironment, modeling the complex ECM nanotopography, will be extremely important for projecting the in vitro finding toward the in vivo cell behavior.

14. Scalable design and fabrication of scaffold is important
Large-area PEG hydrogel nanopattern can mimic the anisotropically aligned ex-vivo myocardium of adult rat heart.
Kim et al. PNAS, accepted for publication

15. Cell Movement through Focal Adhesions (FAs)

16. Some tissue engineering applications
Material rigidity vs Stem cell differentiation
Shear stress vs Endothelial cell
표면경도에 따른 줄기세포의 분화 특성 연구
혈관상피세포의 마이크로 유체에 대한 전단력 영향 연구
Engler et al., Cell (2006)
Wu et al., PNAS (2007)

17. Some tissue engineering applications
Merits of miniaturization: ‘Sensitivity = Output signal / Input signal‘ so as device miniaturized, it gets more sensitive.
Figure. Axon guidance and tissue regeneration on multiscale patterns (courtesy by Prof. Noo-Li Jeon)

18. Some tissue engineering applications
ECM size vs Cell fate
Nanoscaffold vs Tissue engineering
단백질 패턴 사이즈에 따른 세포의 성장과 사멸 연구
스캐폴드 길이 스케일에 따른 조직형성 차이 연구
Chen et al., Science (1997)
Stevens et al., Science (2005) (review paper)

19. Heterotypic co-culture platform
Some tissue engineering applications
Heterotypic co-culture platform
Hepatocyte/fibroblast
200 mm
Stem cell/fibroblast
200 mm
Khademhosseini, Suh, et al., Biomaterials (2004)

20. Kim et al., Biomaterials (2009)
Some tissue engineering applications
Cells on nanogrooves: altered cell shape, migration and polarity
Capillary force lithography
Kim et al., Biomaterials (2009)
10mm
Nanogroove containing devices might serve as useful platforms for understanding the mechanisms of directed cell motility and polarization.