Living Things as Recipients Biomedical Engineering

FIGURE 8.2.14 Initial attempts at an engineering design usually involve principles from the basic sciences and mathematics. Thereafter, improvements come about by application of empirical knowledge obtained from user experiences and structured testing. 

Most biomedical devices fall into this category. Specifications for these devices are often numerous and changing. They sometimes must serve multiple uses and satisfy mnltiple nsers (Shade and Johnson, 2003). In addition, certain of these devices must be fit for individuals with disabilities the devices may need to be modified substantially to perform the intended function on the specific person. 

Even with a lot of improvement, replacement organs or tissues are imperfect compared to the original. BU are robust and redundant. Organs usually have more capacity than is needed to perform their functions instead of one gene to repair and rebuild errors, there are often several organisms can adjust to vastly different environments. BU are wonderful. Therefore, it is unusual for BU to function so poorly that they need replacement. 

Much of the effort to develop replacement BU has come about to serve human needs, and, to a lesser extent, the needs of animals that humans care for. Attempts have been made to replace nearly all tissues and organs of the human body, and these attempts will continue for the foreseeable future. 

As you might suspect, the farther removed the source species is from the species receiving the transplantation, the more difficulty there is in having the BU accepted. Successful crossspecies transplantation is extremely rare transplantations from individual to individual of the same species must be matched for several tissue protein markers (the major histocompatibility complex, or MHC (see Section 6.20)), and even then the recipient must usually take cyclosporin or other suppressors of the immune system in order to avoid rejection. General immune system suppression leaves the recipient susceptible to infection and cancer, but drugs such as cyclosporin A or FK506 interfere only with helper T cell activation and do not cripple nonspecific immune responses (Campbell et al, 1999). 

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