Smalltissue

Smalltissue is a term used in biology and tissue engineering to describe micro-scale tissue constructs produced in vitro. It refers to small, three-dimensional aggregates or tissue-like matrices that model aspects of native tissue while remaining compact enough for routine handling and experimental manipulation. Forms commonly encompassed include cell spheroids, microtissues, and organoids, typically ranging from tens of micrometers to a few millimeters in diameter.

Smalltissue constructs are usually formed from stem cells or primary cells cultured in three dimensions. Common methods use nonadherent culture surfaces, hanging-drop systems, micro-well arrays, microfluidic chips, or three-dimensional bioprinting to assemble cells into aggregates or layered structures. Growth factors, extracellular matrix components, and cell–cell interactions are employed to promote tissue-like organization and maturation.

Applications of smalltissue systems include drug discovery and toxicity screening, disease modeling, and studies of tissue development and regeneration. Because they exhibit 3D architecture and cell interactions absent in two-dimensional cultures, smalltissues can provide more physiologic responses and diffusion gradients, while many platforms enable high-throughput testing on small volumes.

Limitations include incomplete vascularization, maturation differences compared with native tissue, and variability between samples. Standardization of protocols and characterizations varies across laboratories, which can complicate cross-study comparisons. The term is not universally standardized; in some contexts it is used interchangeably with spheroids, organoids, or microtissues, depending on size and complexity.

Related concepts include organoids, spheroids, microphysiological systems, and tissue-engineered constructs.