Module 13

Question 1

Microcontact Printing

Answer 1

Reference Figure 2

Question 2

Micromolding

Answer 2

Reference Figure 3

Question 3

What is Tissue Fusion?

Answer 3

Microtissues adhere to each other and the borders of the microtissues gradually merge to form a large piece of tissue.

Question 4

What are the two methods of templated molding of microtissues?

Answer 4

Sacrificial printing and the Kenzan method

Question 5

Describe the Sacrificial Printing Method

Answer 5

Deposits a sacrificial material (agarose or Pluronic F-127) before microtissues are deposited. After tissue fusion the sacrificial material is removed. (Reference Figure 5)

Question 6

Describe the Kenzan method

Answer 6

Point-shaped microtissues are picked and plugged onto the Kenzan using a pick and place robot. Then tissue fusion occurs. Since the Kenzan helps hold the microtissue in position, a 3D tissue construct with the desired shape can be fabricated. (Reference Figure 5)

Question 7

What is the methodology for Cardioid formation?

Answer 7

Tissue culture plates are coated with PDMS and then with natural mouse laminin (a major ECM component). Silk sutures are soaked in highly concentrated laminin and pinned to the center of the plates. Primary neonatal cardiac myocytes are isolated and plated at the confluence on the culture surface. The cell monolayer will delaminate due to the spontaneous contractions of the cardiac myocytes. The monolayer will move to the center of the plates and wrap on the anchor points. Subsequent remodeling results in cardioid formation.

Question 8

What is poly(N-isopropylacrylamide) (PIPAAm)?

Answer 8

A temperature-sensitive molecule

Question 9

How is PIPAAm used?

Answer 9

A cell sheet is laid on a PIPAAm surface at 37C cells adhere to the dehydrated layer. At 20C cells detach from the hydrated PIPAAm forming an intact cell sheet. The change in temp changes the hydrophilicity and promotes H-bonding that repels the cells to create the detached sheet.