530 R.M.Nerem tation and imaging,has grown substantially,and although,in general,one would not characterize this as a high technology industry,there clearly are areas of commercial application where the limits of our knowledge are being pushed.In the last two de- cades the number of individuals who have identified themselves as biomedical engi- neers,or bioengineers,has dramatically increased,and the number of programs at academic institutions,and the number of students participating in these programs, continues to grow.Finally,both the engineer and the physical scientist are increas- ingly being recognized as important members of the interdisciplinary teams,and their approaches as necessary for research and development at the forefront of the biomed- ical field. With this evolution comes a different type of change-one in which the spectrum of activity has been extended from the organ and tissue level to include cellular phenomena.Just as medicine in general has moved to focus on cell and molecular biology,so have engineers participating in biomedical research and in health care tech- nology applications.This has given rise to what some might call a sub-specialty of bio medical engineering,i.e.,the field of cellular engineering.However,this emerging area of cellular engineering is not just a sub-specialty,because it transcends the nor- mal borders of biomedical engineering,reaching beyond to provide a bridge to the field of biochemical engineering or bioprocess engineering. Just what is cellular engineering?As defined here it is the application of the princi- ples and methods of engineering to problems in cell and molecular biology of both a basic and applied nature.To elaborate on this,let us examine the various elements of this definition.The application of the principles and methods of engineering means to include the ability to quantify information and to establish interrelationships,as well as to model biological,chemical,and physical phenomena.In applying this to problems in cell and molecular biology,it is both cellular and sub-cellular processes which are of interest.Finally,in including applications of both a basic and applied nature,the spectrum of activities ranges from very basic research,i.e.,investigations in cell biology conducted with an engineering perspective,to the development and manufacturing of products based on this science,i.e.,the commercialization of the technology arising out of the science of cell and molecular biology. The development of the technology necessary to grow cells in the laboratory has been critical in the advancement of cellular engineering.In fact,if there is a subtitle to the theme of this presentation,it might be "sex and the single cell."This is because the act of cell replication is an underlying topic,a thread,interwoven throughout the remainder of this text.In the next section we will briefly examine cell culture tech- nology,i.e.,the technology of growing cells in the laboratory. CELL CULTURE TECHNOLOGY The biological cell is the basic sub-unit of any living system,the simplest unit that can exist as an independent living system(2).An individual cell has the ability to rep- licate,to differentiate,to migrate,to communicate,and to perform a whole host of other functions.In effect,this biological cell is a very social animal.It also is an amazingly complex system,the understanding of which challenges our engineering abilities to the utmost.In doing research on cellular and sub-cellular processes,not only can engineers contribute to the basic understanding of the biology of cells,but our engineering skills can be expanded,perhaps far more than we suspect.530 R.M. Nerem tation and imaging, has grown substantially, and although, in general, one would not characterize this as a high technology industry, there clearly are areas of commercial application where the limits of our knowledge are being pushed. In the last two de￾cades the number of individuals who have identified themselves as biomedical engi￾neers, or bioengineers, has dramatically increased, and the number of programs at academic institutions, and the number of students participating in these programs, continues to grow. Finally, both the engineer and the physical scientist are increas￾ingly being recognized as important members of the interdisciplinary teams, and their approaches as necessary for research and development at the forefront of the biomed￾ical field. With this evolution comes a different type of change-one in which the spectrum of activity has been extended from the organ and tissue level to include cellular phenomena. Just as medicine in general has moved to focus on cell and molecular biology, so have engineers participating in biomedical research and in health care tech￾nology applications. This has given rise to what some might call a sub-specialty of bio￾medical engineering, i.e., the field of cellular engineering. However, this emerging area of cellular engineering is not just a sub-specialty, because it transcends the nor￾mal borders of biomedical engineering, reaching beyond to provide a bridge to the field of biochemical engineering or bioprocess engineering. Just what is cellular engineering? As defined here it is the application of the princi￾ples and methods of engineering to problems in cell and molecular biology of both a basic and applied nature. To elaborate on this, let us examine the various elements of this definition. The application of the principles and methods of engineering means to include the ability to quantify information and to establish interrelationships, as well as to model biological, chemical, and physical phenomena. In applying this to problems in cell and molecular biology, it is both cellular and sub-cellular processes which are of interest. Finally, in including applications of both a basic and applied nature, the spectrum of activities ranges from very basic research, i.e., investigations in cell biology conducted with an engineering perspective, to the development and manufacturing of products based on this science, i.e., the commercialization of the technology arising out of the science of cell and molecular biology. The development of the technology necessary to grow cells in the laboratory has been critical in the advancement of cellular engineering. In fact, if there is a subtitle to the theme of this presentation, it might be "sex and the single cell." This is because the act of cell replication is an underlying topic, a thread, interwoven throughout the remainder of this text. In the next section we will briefly examine cell culture tech￾nology, i.e., the technology of growing cells in the laboratory. CELL CULTURE TECHNOLOGY The biological cell is the basic sub-unit of any living system, the simplest unit that can exist as an independent living system (2). An individual cell has the ability to rep￾licate, to differentiate, to migrate, to communicate, and to perform a whole host of other functions. In effect, this biological cell is a very social animal. It also is an amazingly complex system, the understanding of which challenges our engineering abilities to the utmost. In doing research on cellular and sub-cellular processes, not only can engineers contribute to the basic understanding of the biology of cells, but our engineering skills can be expanded, perhaps far more than we suspect