Cells of a multicellular organism are capable of synthesizing various substances to the intercellular environment, which form the intercellular matrix performing different functions.

The matrix:

1) segregates groups of cells, preventing contact between them;

2) regulates cell migration;

3) can induce cell differentiation.

The extracellular matrix consists of the three main components: collagen, proteoglycans and glycoproteins. The consistency of the extracellular matrix depends on the ratio of collagen and proteoglycans (predominance of collagen provides rigidity). The extracellular matrix also includes many other components, such as proteins (fibrin, elastin, fibronectins, laminins and nidogens), minerals (e.g. hydroxyapatite), liquids (lymph, blood plasma containing free antigens). A substantial part of the connective tissue volume is extracellular space filled with an extracellular matrix ; therefore the extracellular matrix determines the physical properties of tissues, such as calcified matrix of bones and teeth, transparent tissue of the cornea, rope-like structure of tendons that can withstand enormous tension. The extracellular matrix is also involved in the regulation of many aspects of cell behaviour , their development, growth, migration, shape, and functions. The extracellular matrix forms a basement membrane between an epithelium and connective tissues, i.e. a thin but strong sheet of fibres that underlies the epithelium. R.A. Weinberg (1989) suggested that the surrounding normal tissue inhibits the growth of tumour cells, as it normalizes them and prevents uncontrolled growth. According to Weinberg, such "normalizing" factors may include interaction between the cells and the extracellular matrix, gap junctional intercellular communication, and cytokines produced by normal cells. The normal micro-environment is the first barrier on the way of a transformed clone to becoming an autonomously growing tumour.

Knowledge of the composition, properties and function of the extracellular matrix is very important for the development of new drugs based on nanoparticles, since the first barriers that they need to overcome on the way to the target cell are blood and extracellular matrix. Structural elements of the extracellular matrix (e.g. collagen) usually have nanoscale organisation and are used in nano-biotechnological methods. Collagen matrices with controlled arrangement of nanoscale fibres can be used for cell culture and implant development.