Table 1.
Characteristics of interstitial cells of Cajal (ICC) subtypes.
| Subtypes | Localisation | Morphology | Functions | Differential Markers | References |
|---|---|---|---|---|---|
| ICC progenitor | - Stomach - Intestine |
Densely packed clusters of oval or circular cells extending within the tunica muscularis | Precursor ICC that can replenish damaged or lost ICC. Smooth muscle produced soluble stem cell factor (SCF) is responsible for its partial commitment into mature ICC | Kitlow, CD44, CD34, InsR, IGF-IR | [30] |
| ICC-MY | - Stomach (antrum only) - Small intestine - Large intestine |
Multipolar cells with branched processes connecting to each other and forming a network around the myenteric plexus in the space between circular and longitudinal muscle layers | - The dominant pacemakers in gastric muscle that generate slow-waves activity - ICC-smooth muscle coupling; electronically coupled via gap junctions or direct contact to propagate slow-waves from ICC to smooth muscle |
Kit, Ano1, M2, M3, VIP-1, SCF-A, NK3 | [9,12,31] |
| ICC-IM | - Distal oesophagus - Stomach - Pylorus - Small intestine - Large intestine |
Bipolar or spindle-shaped cells associated with circular muscle (ICC-CM) or longitudinal (ICC-LM) muscle. Also occur in the connective tissue septa (ICC-SEP) | - Produce spontaneous depolarisations (unitary potentials) that generate low-frequency slow-waves - Mediate neural transmission between enteric nerves and smooth muscle - Stretch sensitivity in gastric muscles |
Kit, Ano1, M2, M3, VIP-1, SCF-A, NK1, NK3 | [15,31,32,33] |
| ICC-DMP | - Small intestine | Multipolar cells associated with the nerve bundles of the deep muscular plexus | - Mediate neural transmission in small intestine | Kit, Ano1, NK1, NK3 | [15,34] |
| Others | - Pylorus (ICC-SM) - Large intestine (ICC-SMP) |
Bipolar and multipolar ICC found in the submucosa (ICC-SM) and submucosal plexus (ICC-SMP) lie between the submucosal connective tissue and the innermost circular muscle layer | - Neurotransmission and pacemaker roles | Kit, Ano1, | [35,36] |
| Cultured ICC | - Cultures from freshly dissociated tissue | Primary culture consists of extensive network of multipolar ICC on the surface of smooth muscle cells. Secondary cultures contain a mix of multipolar and bipolar ICC. Networks of fibroblast-like cells and smooth muscle cells appear. | - Pacemaker properties generating contractility - A change towards a smooth muscle phenotype |
Kit, Ano1, Smooth muscle myosin, M2, M3, VIP-1, VIP-2, SCF-A, SCF-B | [31] |
IGF-IR, growth factor-I receptor; InsR, insulin receptor; M2 and M3, muscarinic receptor types 2 and 3; VIP-1 and -2, vasoactive intestinal peptides 1 and 2, NK1 and NK2, neurokinin receptor types 1 and 2, SCF-A and SCF-B, stem cell factors A and B.