(a) Schematic representation of a spheroid in suspension culture. (b) SEM picture of spheroid after 6 weeks in suspension
These newly formed cilia do not express the acquired abnormalities, but the inherited abnormalities (PCD) are expressed in the culture system (Jorissen et al. 2000a). As the functional abnormalities are also clearly present, this culture can be used for the diagnosis of PCD (Jorissen et al. 2000b). PCD with normal ultrastructure would easily be missed with classical transmission electron microscopy on bioptic material (Jorissen 2000c). Ciliogenesis in vitro has also been achieved by placing the cells in an air-liquid interface culture system (Hirst et al. 2010).
The mucociliary transport rate can be measured in vivo using either the saccharine and/or color test or radioisotope transport testing as well as by measuring ciliary activity in vitro. Inborn disorders of the mucociliary transport as in primary ciliary dyskinesia (PCD) result in absence of mucociliary transport. Nasal nitric oxide (nNO) was found to be 10-fold lower in PCD patients. None of these tests is absolute reliable for the diagnosis of inherited abnormalities. Sequential monolayer-suspension cell culture with dedifferentiation and redifferentiation of the ciliated epithelium improves the reliability of PCD diagnosis.
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