AFM-based nanomechanical characterization of bronchoscopic samples in asthma patients

Asthma is not a single disease, but recently, it is considered as a syndrome characterized through various clinical presentations and different etiopathologies. Large degree of the disease heterogeneity manifests in distinct characteristics that translate into variability of properties at single cell and molecular levels. Here, we conducted measurements of mechanical properties of bronchial tissue samples collected from patients suffering from asthma. The results obtained from different applied protocols for sample preparation may indicate that deep freezing and storage in liquid nitrogen, followed by consecutive unfreezing of tissue samples, preserve tissue mechanical properties as indicated by a parameter referred here as a tissue relative stiffness index. Tissue relative stiffness index quantifies both the degree of heterogeneity and deformability of tissue samples regarding healthy one. These studies demonstrate that the freezing protocol, optimized towards asthma tissue, can facilitate atomic force microscopy use what, together with recent findings on standardization of elasticity measurements, enables the measurements of large group of samples with minimized influence of errors stemming from the applied methodology of tissue stiffness determination.