ORCID Profile
0000-0001-7691-0949
Current Organisation
University of Oxford
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Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.JBIOMECH.2019.109578
Abstract: The airways of the human respiratory system are covered by a protective layer, which is known as airway surface liquid (ASL). This layer consists of two relatively distinct sub-layers a mucus layer (ML), and a periciliary liquid layer (PCL). In addition, the airways are lined with a dense mat of hair-like structures, called cilia, which beat back and forth in a co-ordinated manner and mainly propel the mucus layer. Such interaction between the cilia and mucus is called 'muco-ciliary clearance' (MCC) which is essential to clear the respiratory airways from the inhaled toxic particles deposited on the mucus. The complex nature of lung clearance mechanisms limit the ability to conduct experiments to investigate micro-scale physiological phenomena. As such, modelling techniques are commonly implemented to investigate the effects of biological parameters on the lung muco-ciliary clearance. In the present work, modelling techniques of cilia-ASL interactions - including continuum cilia modelling and discrete cilia modelling - are reviewed and the numerical procedures and level of complexity related to each technique are explained. This is followed by a detailed analysis of the airway surface liquid modelling approaches. In addition, findings of numerical investigations related to the effects of various parameters such as ciliary beat frequency (CBF), mucus rheology, metachronal waves of cilia, surface tension at the PCL-mucus interface, ciliary length, ciliary density, and airway surface liquid depth on the bronchial and tracheal ASL transport are reviewed. This review also explains how these biological parameters can alter the internal power required to perform ciliary beating. Lastly, the main limitations of current numerical works are discussed and significant research directions are brought forward that may be considered in future models to better understand this complex human biological system and its vital clearance mechanism.
Publisher: Elsevier BV
Date: 02-2020
Publisher: MDPI AG
Date: 26-09-2019
DOI: 10.3390/APP9194033
Abstract: Human pulmonary epithelial cells are protected by two layers of fluid—the outer watery periciliary liquid layer (PCL) and the uppermost non-Newtonian mucus layer (ML). Aerosols and inhaled toxic particles are trapped by the ML which must then be removed swiftly to avoid adverse health implications. Epithelial cells are covered with cilia that beat rapidly within the PCL. Such ciliary motion drives the mucus transport. Although cilia can penetrate slightly inside the mucus to assist mucus movement, the motion of the underlying PCL layer within the airway surface liquid (ASL) is significant in mucus and pathogens transport. As such, a detailed parametric study of the influence of different abnormal cilia characteristics, such as low beating frequency, short length, abnormal beating pattern, reduced ciliary density, and epithelium patchiness due to missing cilia on the PCL transport, is carried out numerically. Such abnormalities are found in various chronic respiratory diseases. In addition, the shear stress at the epithelium is assessed due to the importance of shear stress on the epithelial function. Using the immersed boundary (IB) method combined with the finite-difference projection method, we found that the PCL, under standard healthy conditions, has net forward motion but that different diseased conditions decrease the forward motion of the PCL, as is expected based on clinical understanding.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Pahala Gedara Jayathilake.