A holistic framework integrating plant-microbe-mineral regulation of soil bioavailable nitrogen.

Unlabelled: Soil organic nitrogen (N) is a critical resource for plants and microbes, but the processes that govern its cycle are not well-described. To promote a holistic understanding of soil N dynamics, we need an integrated model that links soil organic matter (SOM) cycling to bioavailable N in both unmanaged and managed landscapes, including agroecosystems. We present a framework that unifies recent conceptual advances in our understanding of three critical steps in bioavailable N cycling: organic N (ON) depolymerization and solubilization; bioavailable N sorption and desorption on mineral surfaces; and microbial ON turnover including assimilation, mineralization, and the recycling of microbial products.

Comparative decellularization and recellularization of normal versus emphysematous human lungs.

Acellular whole human lung scaffolds represent a unique opportunity for ex vivo tissue engineering. However, it remains unclear whether lungs from individuals with chronic lung diseases such as chronic obstructive pulmonary disease (COPD) can be appropriately decellularized and recellularized. To assess this, cadaveric human lungs from normal (non-smoking) patients and from patients with COPD (smoking history) were decellularized and found by histochemical and immunohistochemical staining, electron microscopy, and mass spectrometry to retain characteristic histological architecture and extracellular matrix components (ECM) reflecting either normal or COPD, particularly emphysematous, origin.

Comparative assessment of detergent-based protocols for mouse lung de-cellularization and re-cellularization.

Several different detergent-based methods are currently being explored for de-cellularizing whole lungs for subsequent use as three-dimensional scaffolds for ex vivo lung tissue generation. However, it is not yet clear which of these methods may provide a scaffold that best supports re-cellularization and generation of functional lung tissue. Notably, the detergents used for de-cellularization activate matrix metalloproteinases that can potentially degrade extracellular matrix (ECM) proteins important for subsequent binding and growth of cells inoculated into the de-cellularized scaffolds.

Initial binding and recellularization of decellularized mouse lung scaffolds with bone marrow-derived mesenchymal stromal cells.

Recellularization of whole decellularized lung scaffolds provides a novel approach for generating functional lung tissue ex vivo for subsequent clinical transplantation. To explore the potential utility of stem and progenitor cells in this model, we investigated recellularization of decellularized whole mouse lungs after intratracheal inoculation of bone marrow-derived mesenchymal stromal cells (MSCs). The decellularized lungs maintained structural features of native lungs, including intact vasculature, ability to undergo ventilation, and an extracellular matrix (ECM) scaffold consisting primarily of collagens I and IV, laminin, and fibronectin.