The ECM deposited by basal asthmatic and non-asthmatic ASM cells is different in composition but not biological function

Aim: The remodelled asthmatic airway has increased airway smooth muscle cell (ASMC) growth, expanded vasculature, and altered extracellular matrix (ECM). The ECM is the external cellular microenvironment which regulates cell behaviour. Under proliferative, inflammatory, or fibrotic conditions, the asthmaticASM cells (AASMCs) deposit altered patterns of ECM proteins. However, it is unclear whether this is the case under basal, unstimulated conditions. This study aims to examine the composition of the ECM deposited by unstimulated NA (nonasthmatic)- and AASMCs, and biological potential for modulating blood vessel formation. Methods: Primary ASMCs from asthmatic and non-asthmatic individuals were quiesced in 0.1% BSA media after 72 hr of growth. After 24 hr ASMCs were lysed and the ECM either collected in lysate buffer and quantified using BCA, or kept intact and examined for collagen and fibronectin using Picrosirius Red and ELISA, respectively. Angiogenic potential was determined by examining Human Umbilical Vein Endothelial Cell (HUVEC) proliferation on (MTT and Cyquant assays), and attachment to ASMC-derived ECM. Unpaired t-tests were utilised to identify differences between NAASMC and AASMC-derived ECM. Results: Although the total amount of ECM deposited did not change (AASM N = 4 and NAASM N = 3 respectively), AASMCs deposited more collagen (N = 5, P <0.05) and fibronectin (N = 5, P <0.05) compared to NAASMCs (N = 3 and 12, respectively). No difference was observed in angiogenic potential between NAASMC- and AASMC-derived ECM as quantified by HUVEC proliferation (AASM N = 3, NAASM N = 4), metabolic activity (AASM N = 7, NAASM N = 6), or attachment (N = 5 for both groups). Conclusion: Although different in composition, the ECM deposited byASMC is not a primary driver of the altered angiogenic response observed in asthmatic versus nonasthmatic airways. Further, these data suggest that the highly volatile microenvironment of the chronically inflamed asthmatic airway is essential in orchestrating the behaviour of the ASM, demonstrating once more that airway remodelling and airway inflammation in fact go hand-in-hand.