Residual detergent detection method for nondestructive cytocompatibility evaluation of decellularized whole lung scaffolds.

The development of reliable tissue engineering methods using decellularized cadaveric or donor lungs could potentially provide a new source of lung tissue. The vast majority of current lung decellularization protocols are detergent based and incompletely removed residual detergents may have a deleterious impact on subsequent scaffold recellularization. Detergent removal and quality control measures that rigorously and reliably confirm removal, ideally utilizing nondestructive methods, are thus critical for generating optimal acellular scaffolds suitable for potential clinical translation. Using a modified and optimized version of a methylene blue-based detergent assay, we developed a straightforward, noninvasive method for easily and reliably detecting two of the most commonly utilized anionic detergents, sodium deoxycholate (SDC) and sodium dodecyl sulfate (SDS), in lung decellularization effluents. In parallel studies, we sought to determine the threshold of detergent concentration that was cytotoxic using four different representative human cell types utilized in the study of lung recellularization: human bronchial epithelial cells, human pulmonary vascular endothelial cells (CBF12), human lung fibroblasts, and human mesenchymal stem cells. Notably, different cells have varying thresholds for either SDC or SDS-based detergent-induced cytotoxicity. These studies demonstrate the importance of reliably removing residual detergents and argue that multiple cell lines should be tested in cytocompatibility-based assessments of acellular scaffolds. The detergent detection assay presented here is a useful nondestructive tool for assessing detergent removal in potential decellularization schemes or for use as a potential endpoint in future clinical schemes, generating acellular lungs using anionic detergent-based decellularization protocols

Cigarette smoke alters the secretome of lung epithelial cells.

Cigarette smoke is the most relevant risk factor for the development of lung cancer and chronic obstructive pulmonary disease (COPD). Many of its more than 4500 chemicals are highly reactive thereby altering protein structure and function. Here, we used subcellular fractionation coupled to label-free quantitative mass spectrometry to globally assess alterations in the proteome of different compartments of lung epithelial cells upon exposure to cigarette smoke extract. Proteomic profiling of the human alveolar-derived cell line A549 revealed the most pronounced changes within the cellular secretome with preferential downregulation of proteins involved in wound healing and extracellular matrix (ECM) organization. In particular, secretion of secreted protein acidic and rich in cysteine (SPARC), a matricellular protein that functions in tissue response to injury, was consistently diminished by cigarette smoke extract in various pulmonary epithelial cell lines and primary cells of human and mouse origin as well as in mouse ex vivo lung tissue cultures. Our study reveals a previously unrecognized acute response of lung epithelial cells to cigarette smoke that includes altered secretion of proteins involved in ECM organization and wound healing. This may contribute to sustained alterations in tissue remodeling as observed in lung cancer and COPD

Examining the Link Between Leader-Member Exchange and Subordinate Performance: The Role of Task Analyzability and Variety as Moderators

Results from a field study with 152 members of a large urban hospital indicate that the relationship between the quality of leader-member exchange (LMX) and subordinate performance is moderated by perceptions of task analyzability and variety: LMX and performance are found to be significantly related when task challenge is either very high or very low. Under these task conditions, data indicate that there is a positive link between LMX and performance such that a higher quality leader-member exchange correlates with higher levels of performance. On the other hand, analyses also reveal that when tasks are perceived to be moderately challenging, no significant relationship between LMX and performance is present. In other words, these data suggest that characteristics of the task act as moderating agents of the LMX performance relationship. Results are discussed in terms of theory development, managerial implications, and future LMX research