Recent advances in modeling of airway mechanical behaviors in association with airway constrictions in asthma / 医用生物力学

Although it is important to explore potential treatment of chronic obstructive airway diseases such as asthma, as well as to discover interesting biophysical phenomena in airway system, the research on biomechanical models of airway narrowing remains a both appealing and challenging field. However, there have been significant advances during recent years, with number of emerging new models and new approaches. This review article briefly introduces some of the most recent work published in the literature. In particular, those work that emphasize on asthmatic airway narrowing behavior, and strive to explain the corresponding in vivo airway behaviors. More specifically, models that discuss not only individual airway behaviors, but also interactions due to coupling between airways and their surrounding structures are focused on. This includes interesting phenomena involving the airways and the smooth muscle that surrounds the airways, as well as the emergent spatial ventilation patterns due to dynamic airway interaction.

Pathological effects of particulate matter (PM2.5) on pulmonary airways and its roles in asthma pathobiology / 医用生物力学

Asthma is an important respiratory disease that endangers human health, while its complex mechanisms of pathobiology have not been fully understood. Recently, environmental factors are increasingly recognized to play important roles in the pathogenesis of asthma. In particular, the effect of PM2.5 (particulate matter with diameter smaller than 2.5 μm) on the structure and function of pulmonary airways at cell level has become a research hotspot and frontier, and led to many important findings. In this article, the main pathological features, i.e. airway inflammation and hyperresponsiveness were discussed, and recent progress and important findings in pathological effects of PM2.5 on the airway and its mechanism were reviewed, including PM2.5 transport and deposition in the airway, PM2.5 and airway inflammation and damage, PM2.5 and airway remodeling, PM2.5 and airway hyperresponsiveness, PM2.5 and airway smooth muscle cell mechanics via either indirect regulation or direct interaction. The analysis on the role of PM2.5 in airway biomechanics in relation to asthma pathobiology will provide a valuable reference for studying effects of PM2.5 on the respiratory system.

Influence of extracellular matrix proteins and PDGF-BB on airway smooth muscle cells / 医用生物力学

Objective To investigate the influence of three extracellular matrix (ECM) proteins, namely, laminin (LN), collagen type I (Col I), fibronectin (FN) on the morphology and contractility changes in airway smooth muscle cells (ASMCs) induced by platelet-derived growth factor-BB (PDGF-BB). Methods ASMCs were seeded on the culture dish coated with LN, Col I, or FN, respectively, and divided into two groups to be cultured either in the absence or presence of PDGF-BB (10 mg/L) for 0~5 d. Subsequently, cell morphology was examined by the optical microscopy and quantified as the ratio of cell width to length, and the KCl/histamine-induced contractile responses of the cell were measured by optical magnetic twisting cytometry (OMTC). Results ASMCs cultured in the presence of PDGF-BB generally appeared in longer and thinner cell shapes, namely, a smaller ratio of cell width to length, but the cell width/length ratio for ASMCs adhered on LN was relatively bigger than that on Col I or FN. In the absence of PDGF-BB, contractility of ASMCs to KCl increased with the duration of culture, which was independent of the ECM proteins. In contrast, in the presence of PDGF-BB, contractility of ASMCs to KCl or histamine decreased in all situations, but degree of the decrease was smaller for ASMCs adhered on LN than those on Col I or FN. Conclusions The morphology and contractility changes in ASMCs induced by PDGF-BB are influenced by ECM proteins on which cells are grown. For ASMCs adhered on LN, the morphology and contractility changes are relatively smaller than those on Col I and FN. The differential effect of ECM proteins on PDGF-BB induced changes in morphology and contractility of ASMCs is important to fully understand the interactions between ECM proteins, inflammatory factors, ASMCs, and their relation to the pathophysiological mechanism of asthma.

Measurement of respiratory resistance and its variability based on forced oscillation technique / 医用生物力学

Objective To validate the significance of forced oscillation technique (FOT) for diagnosis of asthma by using it to measure respiratory resistance of adult asthma patients and healthy subjects. Methods Respiratory resistance was measured by a hand-held FOT device for 5 adult asthma patients and 5 adult healthy subjects, respectively. The variation of respiratory resistance with time was also compared by statistical analysis. Results The respiratory resistance measured by FOT varied periodically with time in all cases, with the respiratory resistance for asthma patients was (294.98±86.24) and for the healthy subjects was (151.9±39.20) Pa•s/L, respectively, showing significant differences in two groups. Conclusions FOT measurement results showed that asthma patients exhibited a greater magnitude and variability of respiratory resistance as compared to their healthy counterparts, which was in agreement with the conventional diagnosis. FOT can provide a novel method for detecting mechanical parameters of the respiratory system in clinic, and as an important reference particularly for the accurate diagnosis of lung dysfunction, such as asthma.

Universal dynamics behaviors of the cytoskeleton / 医用生物力学

The cytoskeleton of the adherent cell is probably the most complex soft matter in nature. It is composed of hundreds of different proteins that not only interact with each other but also polymerize into long chains and ultimately form a dense network structure. To understand the dynamics of such a complex structure is obviously a great challenge, requiring the joint efforts of multiple disciplines including but not limited to biology, chemistry, physics and physiology. Recently, some important features of the cytoskeleton dynamics have been revealed. For example, the cytoskeleton is far from thermodynamic equilibrium, markedly prestressed, rheologically scale free, and fluidizes in response to a transient stretch. These dynamics behaviors of the cytoskeleton may play important or even determinant roles in many important cell functions such as adhesion, migration and differentiation, and thus further participate in the pathophysiological processes. In this review, we will briefly introduce these dynamics behaviors, describe the results from corresponding studies, and discuss their important implications.