Engineering a 3D Vascularized Adipose Tissue Construct Using a Decellularized Lung Matrix

Critically sized defects in subcutaneous white adipose tissue result in extensive disfigurement and dysfunction and remain a reconstructive challenge for surgeons; as larger defect sizes are correlated with higher rates of complications and failure due to insufficient vascularization following implantation. Our study demonstrates, for the first time, a method to engineer perfusable, pre-vascularized, high-density adipose grafts that combine patient-derived adipose cells with a decellularized lung matrix (DLM). The lung is one of the most vascularized organs with high flow, low resistance, and a large blood–alveolar interface separated by a thin basement membrane. For our work, the large volume capacity within the alveolar compartment was repurposed for high-density adipose cell filling, while the acellular vascular bed provided efficient graft perfusion throughout. Both adipocytes and hASCs were successfully delivered and remained in the alveolar space even after weeks of culture. While adipose-derived cells maintained their morphology and functionality in both static and perfusion DLM cultures, perfusion culture offered enhanced outcomes over static culture. Furthermore, we demonstrate that endothelial cells seamlessly integrate into the acellular vascular tree of the DLM with adipocytes. These results support that the DLM is a unique platform for creating vascularized adipose tissue grafts for large defect filling.

Engineering 3D Vascularized Adipose Tissue Construct using a Decellularized Lung Matrix

Critically sized defects in subcutaneous white adipose tissue result in extensive disfigurement and dysfunction and remain a reconstructive challenge for surgeons; as larger defect sizes are correlated with higher rates of complications and failure due to insufficient vascularization following implantation. Our study demonstrates for the first-time a method to engineer perfusable, pre-vascularized, high-density adipose grafts that combine patient-derived adipose cells with a decellularized lung matrix (DLM). The lung is one of the most vascularized organs with high flow, low resistance, and a large blood-alveolar interface separated by a thin basement membrane. For our work, the large volume capacity within the alveolar compartment was repurposed for high-density adipose cell filling, while the acellular vascular bed provided efficient graft perfusion throughout. Both adipocytes and hASCs were successfully delivered and remained in the alveolar space even after weeks of culture. While adipose derived cells maintained their morphology and functionality in both static and perfusion DLM cultures, perfusion culture offered enhanced outcomes over static culture. Furthermore, we demonstrate that endothelial cells seamlessly integrate into the acellular vascular tree of the DLM with adipocytes. These results support that the DLM is a unique platform for creating vascularized adipose tissue grafts for large defect filling.

Targeting mechanosensitive MDM4 promotes lung fibrosis resolution in aged mice

Aging is a strong risk factor and an independent prognostic factor for progressive human idiopathic pulmonary fibrosis (IPF). Aged mice develop nonresolving pulmonary fibrosis following lung injury. In this study, we found that mouse double minute 4 homolog (MDM4) is highly expressed in the fibrotic lesions of human IPF and experimental pulmonary fibrosis in aged mice. We identified MDM4 as a matrix stiffness–regulated endogenous inhibitor of p53. Reducing matrix stiffness down-regulates MDM4 expression, resulting in p53 activation in primary lung myofibroblasts isolated from IPF patients. Gain of p53 function activates a gene program that sensitizes lung myofibroblasts to apoptosis and promotes the clearance of apoptotic myofibroblasts by macrophages. Destiffening of the fibrotic lung matrix by targeting nonenzymatic cross-linking or genetic ablation of Mdm4 in lung (myo)fibroblasts activates the Mdm4–p53 pathway and promotes lung fibrosis resolution in aged mice. These findings suggest that mechanosensitive MDM4 is a molecular target with promising therapeutic potential against persistent lung fibrosis associated with aging.

Indications that Chymotrypsin-like Elastase 1 is Involved in Emphysema

ABSTRACTEmphysema is an important element of many progressive lung diseases, with chronic obstructive pulmonary disease (COPD) being the most common. With the exception of α 1-antitrypsin (AAT) replacement therapy there are no disease modifying therapies for progressive emphysema. We previously reported that alveolar type 2 (AT2)-cell synthesized CELA1 is neutralized by AAT and that CELA1 is necessary for emphysema in AAT-deficiency. Here, we use mouse models and human tissues to show that CELA1 is required for progressive emphysema. In mice, lung injury was induced with tracheal porcine pancreatic elastase. Cela1 began increasing at 21-days, and Cela1−/−mice were protected from continued airspace enlargement at 42 and 84 days (p<0.01). Aged Cela1−/−mice had less airspace simplification than aged WT mice (p<0.05). In humans and mice, CELA1 mRNA and protein were present in subsets of conducing airway epithelial and AT2 cells. COPD lungs had 3-fold more CELA1 protein than control (p<0.05). Among COPD-associated proteases, only CELA1 was positively and significantly correlated with lung elastolytic activity (p<0.001). Rabbit polyclonal and mouse monoclonal anti-CELA1 antibodies inhibited elastolytic activity of CELA1 mRNA-high but not CELA1 mRNA-low human lungs. CELA1 mRNA levels increased exponentially with age, and smoking reduced that ratio of AAT-neutralized:native CELA1 (p<0.05). CELA1 binding to lung tissue increased 6-fold with biaxial strain (p<0.05). We propose that CELA1 predisposes to progressive emphysema via (1) increased expression with age, (2) reduced AAT neutralization with smoking, and (3) increased CELA1-binding to lung matrix with strain. Anti-CELA1 therapies may represent a novel disease modifying therapy to prevent emphysema progression.ONE SENTENCE SUMMARYWe find that Chymotrypsin-like Elastase 1 (CELA1) is responsible for progressive airspace destruction in multiple mouse emphysema models, show that human lung CELA1 expression and binding to lung matrix are associated with known emphysema risk factors, and demonstrate that anti-CELA1 antibodies largely inhibit lung elastolytic activity in CELA1 mRNA-high lung specimens.