Het effect van radiotherapie op de morfologie van de orale mucosa

De behandeling van mondkanker bestaat doorgaans uit chirurgische verwijdering van de tumor, eventueel gevolgd door radiotherapie. Doel van dit promotieonderzoek was de effecten van radiotherapie op de orale weefsels, in het bijzonder de oppervlakkig gelegen epitheelcellen van het mondslijmvlies (orale mucosa) te onderzoeken. Eerder is met elektronenmicroscopisch onderzoek aangetoond dat onbestraalde orale mucosacellen bij sterke vergroting microplicae (ribbels of plooien) bezitten. Deze microplicae vormen samen met diverse speekselcomponenten een beschermende laag, die functioneert als verdediging tegen bijvoorbeeld micro-organismen. Door radiotherapie beschadigen deze microplicae of kunnen zelfs helemaal verdwijnen. Uit het onderzoek bleek dat dit bestralingseffect zowel bij dieren als bij mensen optrad. Naarmate de radiatiedosis toenam (50 Gy of meer) was de destructie van de microplicae ernstiger. Bij een dosis van 60 Gy of meer bleken ze zelfs helemaal te verdwijnen. Dit proces zou mogelijk een belangrijke rol spelen bij het ontstaan van osteoradionecrose van de kaak en bij het verlies van tandwortelimplantaten na radiotherapie

The defence architecture of the superficial cells of the oral mucosa

The oral epithelium together with the saliva and its components forms a complex structure which is the first line of defence in the oral cavity. The surface of superficial cells of the oral epithelium contains ridge-like folds, microplicae (MPL), which are typical of the surfaces of areas covered with protective mucus. The role of MPL seen on the upper surface of the oral epithelial cells is still unknown. The salivary mucus gel performs a protective diffusion membrane against harmful substances and this membrane is built up by epithelial cells covered by a highly hydrated and viscous gel, where mucins constitute the scaffold. The interaction between the MPL-structure and the mucins is shown in cornea, so that mucins are expressed on the tips of the MPL of the epithelial cells. We hypothesized that the MPL architecture of oral superficial epithelial cells provides the underlying basis for mucins’s protective function as well as in ocular surface. The salivary mucous barrier is required to protect the superficial cells and the MPL-structure together with membrane anchored mucin binding protein (MBP) forms the ground to this mucous barrier. So, oral mucosal barrier complex (OMBC) contains both the MBP-mucin - complex and the MPL-structure of the superficial cells. In the future, studies of the alterations of the salivary mucins and that of the MPL-structure may yield therapeutic opportunities for burning mouth syndrome and perhaps for mucositis causing by irradiation. Focus on cell surface microplication and mucins in oral mucosal biology and oral mucosal diseases is a promising avenue for future research in several ways

Irradiation affects the structural, cellular and molecular components of jawbones

Purpose Emerging evidence shows that changes in the bone and its microenvironment following radiotherapy are associated with either an inhibition or a state of low bone formation. Ionizing radiation is damaging to the jawbone as it increases the complication rate due to the development of hypovascular, hypocellular, and hypoxic tissue. This review summarizes and correlates the current knowledge on the effects of irradiation on the bone with an emphasis on jawbone, as these have been a less extensively studied area. Conclusions The stringent regulation of bone formation and bone resorption can be influenced by radiation, causing detrimental effects at structural, cellular, vascular, and molecular levels. It is also associated with a high risk of damage to surrounding healthy tissues and an increased risk of fracture. Technological advances and research on animal models as well as a few human bone tissue studies have provided novel insights into the ways in which bone can be affected by high, low and sublethal dose of radiation. The influence of radiation on bone metabolism, cellular properties, vascularity, collagen, and other factors like inflammation, reactive oxygen species are discussed.Diabetes mellitus: pathophysiological changes and therap

Microplicae: specialized surface structure of epithelial cells of wet-surfaced oral mucosa

The surface structure of the superficial cells of the oral mucosa is decorated with numerous membrane ridges, termed microplicae (MPLs). The MPL structure is typical of the epithelial surfaces that are covered with protective mucus. Cell membrane MPLs are no longer seen as passive consequences of cellular activity. The interaction between MPLs and the mucins has been demonstrated, however the role of MPL structure seen on the upper surface of the oral epithelial cells is speculative. The cell surface is of potentially great significance, as it harbors many markers for refined prognosis and targets for oral mucosal diseases and cancer therapy. With these aspects in mind, we conducted the present review of the MPL structure and function in order to form the basis for further studies of MPLs of the oral epithelial cells