Intro And History 3

Question 1

What is contact guidance

Answer 1

Effect of layout of local environment on cell shape and cell migration
Both physical (topography) and chemical (adhesive) can result in contact guidance
Eg. Fibroblasts grown on aligned collagen gel, cells line up with direction of collagen fibres

Question 2

How can cells on glass fibres exhibit contact guidance

Answer 2

If bead is large- radius of curvature is large, cells spread

If small- cant spread well, distort

Question 3

Outline the process of micro photolithography

Answer 3

Substrate is coated with a silicon layer and photoresist
Resist exposed to light using a micropattern
Areas hit by light are chemically altered and can then be removed
Substrate is exposed allowing etching eg. Addition of silicon dioxide
Substrate removed from exposed areas
When rest of resist is removed patterned topography is exposed

Question 4

How does micro topography influence cell behaviour

Answer 4

Grooved surfaces provide a strong cue for cell guidance and alignment
There is more alignment of cells in deeper grooved surfaces
Epithelial cells only aligned better as single cells, not when in contact
Behaviour is cell type dependent
Response increases with density

Question 5

How do you create hydrophobic micropatters

Answer 5

Pattern adhesiveness is determined by exposure to alkylchlorosilane
Results in covalent binding of hydrophobic groups
Exposed surface becomes poorly adhesive for cells
Photoresist then removed exposing hydrophobic surface
Cells dont like hydrophobic surfaces
Cells can spread on the glass with no methylsilane

Question 6

What are the differences between patterned topography and patterned adhesion

Answer 6

With topography, denser the features, greater the response

Cell adhesion, less dense greater response

Question 7

How do neurones respond to adhesiveness and grooves?

Answer 7

Can be guided by adhesiveness but grooves are ignored

Question 8

How do single/colonies respond to planar and grooved surfaces?

Answer 8

Single:
Planar - normal cell morphology
Groove - elongated
Colony:
Planar - normal appearance
Groove- no great distortion, some of cytoskeleton aligns with grooves

Question 9

What are some current applications of nanofabrication

Answer 9

Mesenchymal stem cells on surface with nano pillars in ordered or disordered fashion
In ordered environment cells remained undifferentiated
In disordered environment they differentiated