Section 1 Cell Differentiation and Proliferation

Objectives 1.Understand cell signaling influences on cell differentiation and proliferation. Explain how different signals cause different cell differentiation of the same stem cell. Use “growth factors” to explain cell proliferation promoters and inhibitors. 2.Graph proliferation based on stem cells growth. Graph concentration of signal versus number of colonies that grow. 3.Understand how proliferation is important factor in tissue engineering. Explain importance of culturing large number of cells for research.

Tissue Engineering Tissue engineering uses cells, biomaterials, and engineering methods to improve or replace biological functions. In particular, tissue engineering focuses on partial and whole tissue repair and regeneration. Tissue engineering is often used as a synonym for regenerative medicine. However, regenerative medicine often focuses on the stem cell based therapies.

Tissue Engineering There are four fundamental technologies involved in tissue engineering: 1.Scaffolding for cell proliferation and differentiation 2.Isolation and culturing of cells 3.Drug delivery system of growth factor 4.Maintenance of space to induce tissue regeneration Together theses technologies are able to assist and accelerate the regeneration and repairing of defective and damaged portions or whole tissues. We will focus on cell proliferation and differentiation and well as culturing of cells.

How Is Growth Controlled? Growing cells bind small amounts of growth factors that stimulate cell division. Cell surface receptors recognize each growth factors. They fit like a lock and key and are very specific. Growth factors work by triggering downstream effects. Binding often causing phosphorylation of proteins which then activates regulatory proteins that trigger cell division.

Stem Cells Stem cells have three main characteristics: 1.Not terminally differentiated 2.Capable of unlimited division 3.Self renewing: cells can remain stem cells or differentiate Into different cell types Stem cells are pluripotent, meaning stem cells have the ability to become many cell types under the right conditions and signals.

Cell Differentiation Differentiation is dependent on the signals and growth factors the stem cells are exposed to.

Cell Proliferation Once differentiated cells are created, the goal is to culture these cells to produce large numbers of them. Tissue engineering involves studying these large cell cultures. Cell signals and growth factors are used to conduct this task. Some signals can inhibit the growth of cells, so its our job as tissue engineers to figure out what growth factors and signals increase cell proliferation the best.

Student Activity Goal: Add growth factors to stem cells to determine the best growth factor for cell proliferation.

Student Activity Materials: Agar plates Yeast Boric acid Ethanol Sucrose Apple juice Vinegar Glass rods Test tubes

Student Activity Procedure: 1.Apply “growth factors” to petri dishes using the micropipettes. 2.Add differentiated stem cell culture to petri dishes. 3.Allow 48 hours for growth. 4.Count number of colonies on plates. 5.Graph results: The horizontal axis will the different growth factors and the vertical axis will be the number of colonies formed. Note: Use correct micropipetting technique when administering the growth factors and differentiated cells. We want to be accurate.

Student Activity Questions: What is cell proliferation? How did each growth factor affect the yeast growth? Why is cell proliferation important? How can inhibitors be useful to cell proliferation? What others ways do you think you can promote cell proliferation? Inhibit cell proliferation? Why is culturing large numbers of cells important for tissue engineering?