Tissue-engineering scaffolds: can we re-engineer mother nature?

The objective of tissue engineering is to apply the foundations and innovations of biology, medicine and engineering to develop viable, 3D substitutes that support, sustain and/or restore the function of damaged, diseased or lost tissues and organs. Tissue engineers historically have used formulations of cells and scaffolds in conjunction with chemical and/or mechanical conditioning in attempts to fabricate tissue and organ mimetics. Since its inception, the field of tissue engineering has been pursuing the concept of an ‘ideal’ scaffold. In recent years, considerable focus has been placed on identifying sources of cells for developing tissue-engineering constructs. At the most fundamental level, tissue and organ systems can be described as spatially and functionally defined compartments (microenvironments) containing cellular elements held in place by an extracellular matrix (ECM). The resident cells provide tissueand organ-specific functions, and the ECM establishes the 3D architecture necessary to carry out physiologic processes. Beyond its structural role, the ECM functions to regulate aspects of cell proliferation, migration, differentiation, apoptosis and the global evolution of organ and tissue phenotype. Tissue-engineering scaffolds must also serve to regulate the biology of the local cell population, and establish the physical boundaries and architecture of engineered tissues. We believe there is ample justification that consideration and effort equal to that directed at identifying donor cell sources, should be invested in developing biomaterials for use as tissue-engineering scaffolds.