acellular

Acellular refers to something that does not consist of cells. In biology, the term is used to describe entities or materials that lack cellular organization. This contrasts with cellular life-forms that are built from cells.

Examples include acellular infectious agents such as viruses, viroids, and prions. Viruses are composed of genetic material enclosed in a protein coat and lack the full cellular machinery of life; viroids are even simpler RNA molecules without a protein coat; prions are misfolded proteins lacking nucleic acids. Because they lack cells, these agents rely on host cells to replicate and propagate.

In medicine and biotechnology, acellular approaches are used to reduce immune reactions or to provide purified components. Acellular vaccines contain purified antigens from a pathogen rather than whole cells or organisms, such as acellular pertussis vaccines.

Acellular scaffolds and matrices are produced by removing cellular components from donor tissues (decellularization) to yield extracellular matrix structures used in regenerative medicine.

In tissue engineering and wound care, acellular dermal matrices are used as scaffolds in surgery. Limitations include that acellular products may lack certain cells required for some healing processes and may rely on host cell repopulation to achieve full integration. Overall, the term “acellular” highlights the absence of cellular components, with applications spanning virology, immunology, and regenerative medicine.