Emergence of Patterned Stem Cell Differentiation Within Multicellular Structures

1. Emergence of Patterned Stem Cell Differentiation WithinMulticellular Structures Tongcheng Qian April 27th, 2009

2. Outline • Introduction • Emergence of patterned stem cell differentiation within multicellular structures • Summary

3. Introduction Properties Self-renewal Potency embryonic stem cells adult stem cells • Totipotent • Pluripotent • Multipotent • Oligopotent • Unipotent

4. Morphogenis • Spatial gradients of diffusible factors known as morphogens • Mechanical force mechanical stiffness of the local tissue environment contractile activity of the cells

5. How the mechanical force affect the cells The example shows the dramatic difference in morphology that the same cells will assume after only 4 hours in different matrices Cellular mechanics involves three steps: mechanosensing, mechanotransduction mechanoresponse.

6. Mechanisms of force sensing gain or loss of binding sites mechanosensitive ion channels can be regulated by membrane tension receptor–ligand bonds

7. Matrix Elasticity Directs Stem Cell Lineage Specification Tissue elasticity and differentiation of naive MSCs Differnet stiffness of the matrices that mimic different tissues can lead the MSCs differentiate into relevant cell lineage respectively

8. Emergence of patterned stem cell differentiation within multicellular structures Patterned stem cell on a flat surface Staining: ALP, Fast Blue RR cbfa-1 Lipid droplets, oil red O PPAR r Nuclei, DAPI

9. Different patterned size

10. Different patterned shape

11. where F, E, I, L, and delta are the bending force, Young’s modulus,moment of inertia, length, and resulting deflection of the post,respectively

13. Blebbistatin Y-27632 inhibitor of the Rho-associated protein kinase ML-7 myosin light chain kinase (MLCK) inhibitor

14. All the patterned MSCs in low force distribution area will differentiate into adipocytes, whereas MSCs in high force distributed area will differentiate into ostogenic cells, this happens in two dimensional surface, and what about three dimensional patterned cells?

15. Patterning of differentiation in three-dimensional structure

16. Summary • The specification and differentiation of stem cells can be mostly decided by the diffusible signals and mechanical force. • The mechanical force finally converted into biochemical signals. • To understand the mechanisms can be very helpful for solving many problems.

17. References 1, Stem cells 2008; 26:2921-2927 2, Cell 2006; 126:677-689 3, Nature Reviews 2006; 7:265-275 4, Development 2003; 130:2027-2037 5, PNAS 2003; 100:1484-1489