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Teaching Guide
Activity 2: Grades 5-8
Encouraging Cell Growth
 

As you learned in "Body on a Bench," researchers have been able to culture liver stem cells onto the surface of a silicon chip. The chip has been riddled with tiny channels that allow nutrients to flow continuously past the developing cells. The flow within these artificial "vessels" also allows for the removal of waste materials, just as blood vessels do in a real liver. In fact, the entire chip functions just like a living liver, encouraging the liver stem cells to develop just as they would in a living organism.

This liver chip could provide scientists with a valuable tool in the study of liver treatment and disease. This tiny artificial liver can offer a closed living system in which to test various drugs and their interactions with liver cells. By administering such drugs to laboratory-maintained tissues, researchers are able to control and evaluate the actions of various therapies without using animals or endangering a living patient. The success of this culturing technique may one day lead to the development of a whole host of organ "chips," and radically reduce the need for organ transplants in the future.

 

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Substrate Enhancement
In order to coax liver cells into growing on silicon chips, the exposed surface of the chip must be specially prepared. First, it is finely etched with a texture of microscopic pores. Then, the surface is chemically treated to mimic the structural elements of the liver's natural environment. The result is an artificial scaffolding on which liver cells adhere and function.

In this activity, you'll have the opportunity to test how the surface coating of a substrate affects the success of a biofilm. A biofilm is a sticky, slimy coating made from carbohydrates. It is produced by colonies of bacteria and algal cells.

 

This activity page will offer:

  • Insight into factors that affect cell adhesion.
  • An opportunity to observe the production of a biofilm.
  • An opportunity to test the effects of surface coatings on the production of biofilms

MATERIALS

  • Plastic 2-liter container (with top half removed)
  • Spring water
  • Cup of water from an aquarium overgrown with algae
  • Plastic slides
  • Cup
  • Waterproof clay (from florist supply store or craft store)
  • Plastic wrap
  • Petroleum jelly
  • Suntan lotion



PROCEDURE

  1. Obtain a plastic 2-liter container that has been prepared by your instructor.
  2. Fill the container 3/4 full with spring water.
  3. "Inoculate" the container by adding a cup of water that has been taken from an aquarium environment overgrown with algae.
  4. Coat both sides of a plastic microscope slide with a thick layer of petroleum jelly.
  5. Place one end of the coated slide into a marble-sized lump of waterproof clay, then place the coated slide into the container, clay-side down. Make sure that the clay offers a stable base to keep the slide supported upright in the water column.
  6. Repeat step 5 using a slide that has been coated with suntan lotion.
  7. Repeat step 5 using a slide that has not been coated with any material.
  8. Cover the top with plastic wrap to prevent the evaporation of water.
  9. Place the covered container with its three upright slides in a location where the setup will not be disturbed.
  10. Wait about ten days. Carefully remove the slides. Do not disturb any film that may have grown on the surface of the slides.
  11. Closely examine the surface of each slide by holding it up to a light. Which slide appears the least transparent, having the most dense bioflim coverage? Now touch each surface. Compare and contrast their appearances and feel.

Questions

  1. Where did the slime-producing microorganisms come from?
  2. In step 7, a slide that was not coated with any materials was placed into the container. Explain.
  3. How did the biofilm coverage compare? What factors seemed to promote the growth of a biofilm?
  4. How can you apply what you've learned in this activity to the content of this segment of SAF?

EXTENSIONS

3D Sculpture
Remember how the liver chip looked in the program? Think about its pitted surface and the network of pores that transported nutrients and waste to and from the liver cells. Then, use a variety of art materials to construct a sculpture that represents the liver chip. Your sculpture can either be a scientific model that accurately portrays this liver chip or it can be a creative, artistic representation.

Science Fiction Writing
Imagine being inside a microscopic submarine whose mission is to explore the liver chip. Using this unique perspective, create a fictional log that describes what you observe as you navigate in and around the chip structure.

WEB CONNECTION

Liver Cell
http://ilil.essortment.com/liverscellsstr_ricl.htm
This site offers an overview of liver cell structure and function.

CNEWS Science
http://www.canoe.ca/CNEWSScience0104/23_liver-ap.html

An online article for the general public that describes the success in culturing liver cells on a silicon chip.

Artificial Liver Trial
http://www.uchospitals.edu/news/ELAD.html

This site describes the use of liver cell cultures in assembling an artificial liver.


Answers

The activities in this guide were contributed by Michael DiSpezio, a Massachusetts-based science writer and author of "Critical Thinking Puzzles" and "Awesome Experiments in Light & Sound" (Sterling Publishing Co., NY).

Academic Advisors for this Guide:

Corrine Lowen, Science Department, Wayland Public Schools, Wayland, MA
Suzanne Panico, Science Teacher Mentor, Cambridge Public Schools, Cambridge, MA
Anne E. Jones, Science Department, Wayland Middle School, Wayland, MA

 

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