Sabrina Jedlicka. Interactions of Neurons and Materials

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1 Sabrina Jedlicka Interactions of Neurons and Materials

2 Neurological Disorders Over 600 known neurological disorders ú Diseases of the CNS and PNS Epilepsy Alzheimer s Parkinson s Etc. ú Diseases that attack the nervous system Infections Cancers ú Physical Injury ú Stroke ú Sensory For most, treatment options are extremely limited The disease/disorder mechanism is highly varied, as is the prognosis.

3 Primary Goals Analyze the function of the nervous system Develop methods to restore damaged neurological functions Create artificial neuronal systems

4 How to grow neuronal cells in culture From proliferation to differentiation There is a subset of bioengineering that focuses on developing biomaterials for integration with neural systems, either in vivo or in vitro.

5 Cell- Material Interactions Neural Stem Cells Cellular Mechanotransduction Cellular Biomechanics Surface-Induced Chemotransduction

6 Definitions Cellular Mechanotransduction ú The mechanism by which cells convert mechanical signals in biochemical responses Cellular Mechanobiology ú Characterization of cell mechanics Cellular Surface Induced Chemotransduction ú The mechanism by which cells respond to surface-bound signals (such as ECM proteins)

7 Why does chemomechanotransduction matter? Cell Proliferation ú Disease States ú Propagation of sufficient cell numbers for therapeutics Cell Communication ú Force translation via cell-cell contacts ú Downstream biochemical signaling Cell Differentiation ú Development of useful cell-based models for research ú Differentiation of cells into more mature phenotypes for transplantation

8 Research History

9 Research History Mesenchymal stem cells differentiate based on substrate elasticity (Engler et al., 2006) Engler, A. J., Sen, S., Sweeney, H. L., & Discher, D. E. (2006). Matrix elasticity directs stem cell lineage specification. Cell, 126(4),

10 Developing Bio-inspired Materials Ingber, D. E. (2006). Cellular mechanotransduction: Putting all the pieces together again. Faseb Journal, 20(7),

11 C17.2 Neural Stem Cells Neuronal differentiation is controlled via serum withdrawal (starvation), which usually results in a homogeneous population of neurons But

12 Controlling Differentiation In vivo processes are highly coordinated and elegant. Some of the proteins involved in asymmetric division are known (Example: Numb), but some of their roles are not clearly defined However, in a lab setting, when you are trying to regrow neurons for therapeutic purposes you often start with stem cells in a petri dish, which does not have the elegant coordination of signals to trigger cell changes at the right time and place.

13 Goals: Enhancing Differentiation Controlling the chemomechanical environment may allow us to provide the right signals to stimulate NSCs to become post- mitotic neurons of phenotype X for treatment of a certain disease. Alternatively, it will provide a means to produce new model system to study novel drugs And lots of other applications!

14 NSCs and Mechanosensing: The Research Question How do material cues impact differentiation of NSCs?

15 Materials Inspiration Hardwired or Environmentally Influenced Activity Independent Mechanisms Stem Cell Differentiation Migration Environmental Factors Influencing Activity Independent Mechanisms ECM Composition and Concentration Growth Factors Morphogens Cell-Cell Interactions Mechanical Environment Maturation We can control or mimic many of these factors

16 Materials Design Mimic the extracellular environment during early corticogenesis Diverse Neuronal Population ECM Is Critical for Appropriate Cell Differentiation and Migration Laminin Fibronectin Collagen Lamellipodia formation and lamellipodia/filopodia extension Src FAK Cas Shc GRB2/mSos Cadherin containing cadherins junctions Cdc42 Cell polarity Rac PAK Jnk Rho Ras P1-3K Erk C-Fos/c -Jun FGF pathways Gene Transcription SCG10 Axonal guidance Neuronal cytoarchitecture

17 Examine Cellular Response To Material Surfaces Investigate Cell Type Diversity Changes Cell Type Diversity in Population Flow Cytometry Analysis of Cell Types on Control Surfaces Neurons Astrocytes β-tubulin GFAP III 25-30% 10-20% Oligodendrocyte s CNPase 3-5% Fibroblasts Vimentin 55-65%

18 Material composition affects cell type diversity RGD/YIG/NID More Neurons RGD/YIG/IKV/VSW More Astrocytes *

19 Mechanical Stimulation of Neuronal Differentiation Control of Neuronal Division??

20 The Methods Polyacrylamide: Well established material in mechanosensing Activate coverslips Pipette gel solution onto activated coverslips & cover After solidification remove top coverslip and treat with Collagen I Young's modulus vs. cross-linker fraction as determined by mechanical testing (Rowlands, A. S., P. A. George, and J. J. Cooper-White (2008) AJP: Cell Physiology 295.4: C )

21 Mechanical Influences on Asymmetric division (and ultimately differentiation) Extent of C17.2 stem cell differentiation depends on the stiffness of the substrate Softer substrates promote differentiation into neurons and the formation of longer neurite extensions, as shown by analysis of the expression of neuron- specific β- tubulin III 140 Pa Pa

22 Some Surfaces lead to 100% neuronal populations

23 Proliferation and Neurogenesis The degree of cell proliferation is controlled in part by the degree of asymmetric cell division When a progenitor cell divides it can make any variety of cell combinations: ú Two progenitors ú One progenitor and one neuron ú One progenitor and one astrocyte ú Etc.

24 Differences in Division Type?

25 Results During differentiation, number of asymmetric divisions is greater on glass over the soft surfaces. Asymmetric Division during Differentiation on Various Substrates

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27 Results Cell Death is also reduced on soft surfaces compared to glass. 14# Cell'Death' 12# 10# Number'per'day' 8# 6# 4# 2# 0#!2# 7.50%# 3.75%# 1.875%# 0.94%# Percent'Serum' 140#Pa#gel# Collagen#Coated#glass# Glass#

28 Results Cells grown on softer surfaces form functional synapses (red: synaptophysin, green: Homer) Softer surfaces yield a more homogeneous, more mature population of neurons

29 Can division events be controlled? Can division events be correlated to fate? Nanomaterials Nanomanipulation

30 Nanomaterials Concentration Dependent Effect Useful for Imaging, Sensing, Etc. Long-term Impacts?

31 Nanomaterials

32 Nanomaterials Hypothesis Substrates are forcing cytoskeletal changes, altering the division dynamics, force transduction, and subsequent gene expression NSC Day 5 Cell Division Peaks Day 10 Asymmetric Division Peaks Day 10 Nestin expression falls Day Most prominent morphological changes Tuj1 expression peaks Day 23 CNTs are interacting with cytoskeleton, altering the division dynamics ** early redistribution of actin (i.e. mechanical remodeling!) CNTs are altering gene expression, but how?

33 Nanomaterials Data When materials are added at day 5, the population decreases in the presence of CNT. When added at day 10 and day 15, a slight increase is observed. The presence of CNT increases the % of cells expressing β-tubulin III. There is an increase in % of cells which do not express phenotypic protein markers tested to date ~50% of Low express nestin Low conc High conc Total Population for day 5 addition Regular DNACNT DNA RNACNT RNA Fraction Low Concentra,on Neuronal Internal destabilization or oompliance changes? Regular DNAc DNA RNAc RNA

34 Can division events be controlled? Can division events be correlated to fate? Nanomaterials Nanomanipulation

35 Nanomanipulation In collaboration with Daniel Ou-Yang, Dimitrios Vavylonis, and Susan Perry

36 Nanomanipulation Hypothesis In collaboration with Daniel Ou-Yang, Dimitrios Vavylonis, and Susan Perry

37 Implications? Establishing a causal link between division mode (and related factors) and final cell fate Control of differentiation = potential therapeutic solution Advanced understanding of division mechanisms

38 Much more work to be done

39 Questions?