Acellulaire

Acellulaire is a term used in biology and medicine to describe something that lacks cells. In general, it refers to organisms or materials that do not contain intact cellular structures. The concept is distinct from cellular, which denotes the presence of cells.

In biology, several infectious agents are acellular. Viruses, viroids and prions are typically described as acellular because they do not possess a complete cell type and rely on host cells to replicate. Viroids are small, single-stranded RNA molecules that infect plants; prions are misfolded proteins that propagate by inducing misfolding in normal proteins. In contrast, bacteria, fungi and other microorganisms are cellular.

In medicine and tissue engineering, acellularity commonly refers to tissues or matrices from which cellular material has been removed, leaving an extracellular matrix scaffold. These acellular matrices, derived from donor tissues or animal sources, are used to support tissue repair and regeneration. Examples include acellular dermal matrices and decellularized organs, as well as small intestinal submucosa. The decellularization process aims to reduce immunogenicity while preserving ECM structure and bioactive cues that guide cell repopulation.

Acellular vaccines contain purified antigens rather than whole pathogens, reducing reactogenicity while potentially requiring multiple components to achieve protection. The pertussis component in acellular pertussis vaccines is a well-known example, often combined with diphtheria and tetanus toxoids.

See also: cellular biology; decellularization; acellular vaccines; extracellular matrix.