Successful tissue regeneration requires a proper mix of scaffold, cell populations and regulatory molecules. These bioactive molecules, or growth factors, play an important role in inducing growth and differentiation of various types of cells. They include platelet-derived growth factors (from platelets in the blood) and bone morphogenetic proteins.

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Among the many questions related to the use of growth factors are these:

• Do growth factors easily bind to scaffold components?
• Do the chemicals freely diffuse across scaffold surfaces?
• Can scaffolds be “imprinted” with growth factors, allowing researchers to control and vary the concentration of factors through the structure?
• How long do the growth factors remain in association with scaffold components?
• What concentration of growth factor yields the optimal differentiation outcome?

Answers to these questions require sophisticated chemical analysis techniques. Because cells are extremely sensitive to the concentration of growth factors, determining the appropriate concentration of growth factor is an essential step in the control of the differentiation cascade. A critical chemical concentration range is required for proper cell response and health. For example, osteogenic (bone) precursor cells will respond well to an appropriate range of the growth factor bone morphogenetic protein 2 (BMP-2). Within this range the cells will proliferate and differentiate to produce osteoblastic cells.

However, further study is required to determine the appropriate concentration of BMP-2 at various locations within the scaffold in order to verify the potential success of their engineered scaffold.