Compatibility Problems in Artificial Organs

Abstract

In considering artificial organs and host compatibility, an initial assumption is that an artificial organ must reproduce or mimic normal organ physiology. This analysis is facilitated by classifying tissues and organs into two groups relative to their microvascular beds: 1) regulatory or homeostatic, and 2) nutritional. Regulatory beds modify blood as part of their homeostatic function, i.e., kidney and lungs; nutritional beds meet the metabolic needs of tissues, i.e., heart and brain, without which tissue death would occur. Additional examples are given. Complete analysis of regulatory organ function must include all functions, not only the major one. For example, in addition to gas exchange the lung has an important filtration function, and vasoactive materials and possibly fibrinolytic enzymes are stored, released, and possibly synthesized in the lung. Nonregulatory organs also pose problems in physiology mimicry, which are detailed. There are other areas of compatibility problems due to the uniqueness of living material beyond that of precise organ physiology. They are: 1) surface or gas effects on solid and fluid constituents of blood; 2) immunologic problems; 3) hydrodynamic effects; 4) biochemical effects; 5) potential carcinogens; 6) potential teratogens; 7) a group of physical incompatibilities which include heat, electricity, and mechanical support problems.