chimeric

Chimeric refers to something composed of parts from different origins, analogous to the mythical chimera. In biology and medicine, the term denotes organisms, cells, tissues, or molecules that contain two or more genetically distinct lineages.

Chimerism in organisms occurs when two zygotes fuse early in development, creating a single individual with two or more genetically distinct cell populations. In humans, this can result from the exchange of cells between twins in utero or from procedures such as bone marrow transplantation, yielding a person with two genetically distinct cell populations (microchimerism or full chimerism). Natural chimeras have been documented in mammals, birds, and plants, though they are rare.

Chimeric proteins and genes describe constructs that fuse sequences from different sources to form a single molecule with combined properties. Chimeric antibodies combine components from different species and are used in research and therapy. A prominent example is the chimeric antigen receptor (CAR) used in CAR-T cell therapies, where an antibody-derived recognition domain is fused to intracellular signaling domains to redirect immune cells against specific targets.

In botany and horticulture, chimeras occur when a plant contains genetically distinct cell lines in different tissues, often producing variegated leaves or other mixed traits. Chimeric approaches also appear in synthetic biology, where domains from diverse proteins are combined to create novel functions.