Decellularized tissue engineered pericardium as replacement for tricuspid valve in cardiac surgery

Department of Cardiac, Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover Germany and Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Hannover Medical School, Hannover, Germany, The 6th International Medical Congress for Students and Young Doctors, May 12-14, 2016Introduction: Tricuspid valve replacement is the last treatment choice in tricuspid valve pathology. The choice to insert mechanical or bioprosthetic valve remains controversial. Both prostheses have some limitations such as infection, risk of thromboembolism, need for life-long anticoagulation or limited durability. The following study aimed to develop a novel tissue-engineered tricuspid valve based on decellularized pericardium allograft. Materials and methods: Fresh ovine pericardium was harvested at the local slaughter house and decellularized using detergents. For disinfection all samples were treated for 24h with Phosphate Buffered Solution supplemented with 1% gentamicin and 1% streptomycin. The effectiveness of decellularization was evaluated by histological staining (hematoxylin-eosin, Movat’s Pentachrom and Van Gieson), Isolectin B4 staining (a-gal xenoantigen) and by DNA-quantification. Two valvular leaflets were manufactured out of decellularized pericardium and sutured ex-vivo into the tricuspid annulus of an ovine heart and suspended on papillary muscles. Hydraulic test were performed to prove valve competency. Discussion results: After detergent treatment pericardial tissue has been converted in a cell-free scaffold as proven by standard histological analysis. Immunofluorescent examinations revealed the absence of a-gal xenoantigens. DNA-quantification showed a substantial reduction in DNA content compared to the normal tissue. The alignment of collagenous fibers in decellularized scaffolds appeared well-preserved and was not affected by detergent decellularization procedure as proven by histological staining. Graft disinfection and storage in antibiotic solution after decellularization did not affect the texture of the scaffold. Furthermore, two leaflet structure created out of decellularized pericardium and surgically sutured in tricuspid position of ovine heart resulted in a competent valve prosthesis. Conclusion: The present results have shown successful decellularization of the ovine pericardium using detergents. Decellularized pericardial allograft can be used in cardiac surgery as a scaffold for valvular tissue engineering or for in-vivo guided tissue regeneration in tricuspid valve replacement

Competitive Activity-Based Protein Profiling Identifies Aza-β-Lactams as a Versatile Chemotype for Serine Hydrolase Inhibition

Serine hydrolases are one of the largest and most diverse enzyme classes in Nature. Most serine hydrolases lack selective inhibitors, which are valuable probes for assigning functions to these enzymes. We recently discovered a set of aza-β-lactams (ABLs) that act as potent and selective inhibitors of the mammalian serine hydrolase protein-phosphatase methylesterase-1 (PME-1). The ABLs inactivate PME-1 by covalent acylation of the enzyme’s serine nucleophile, suggesting that they could offer a general scaffold for serine hydrolase inhibitor discovery. Here, we have tested this hypothesis by screening ABLs more broadly against cell and tissue proteomes by competitive activity-based protein profiling (ABPP), leading to the discovery of lead inhibitors for several serine hydrolases, including the uncharacterized enzyme α,β-hydrolase domain-containing 10 (ABHD10). ABPP-guided medicinal chemistry yielded a compound ABL303 that potently (IC[subscript 50] ≈ 30 nM) and selectively inactivated ABHD10 in vitro and in living cells. A comparison of optimized inhibitors for PME-1 and ABHD10 indicates that modest structural changes that alter steric bulk can tailor the ABL to selectively react with distinct, distantly related serine hydrolases. Our findings, taken together, designate the ABL as a versatile reactive group for creating first-in-class serine hydrolase inhibitors.National Institutes of Health (U.S.) (Grant GM57034)National Institutes of Health (U.S.) (Postdoctoral Fellowship Grant GM086040)Skaggs Institute for Chemical Biolog

Evaluation of NHS carbamates as a potent and selective class of endocannabinoid hydrolase inhibitors

Monoacylglycerol lipase (MAGL) is a principal metabolic enzyme responsible for hydrolyzing the endogenous cannabinoid (endocannabinoid) 2-arachidonoylglycerol (2-AG). Selective inhibitors of MAGL offer valuable probes to further understand the enzyme’s function in biological systems and may lead to drugs for treating a variety of diseases, including psychiatric disorders, neuroinflammation, and pain. N-Hydroxysuccinimidyl (NHS) carbamates have recently been identified as a promising class of serine hydrolase inhibitors that shows minimal cross-reactivity with other proteins in the proteome. Here, we explore NHS carbamates more broadly and demonstrate their potential as inhibitors of endocannabinoid hydrolases and additional enzymes from the serine hydrolase class. We extensively characterize an NHS carbamate 1a (MJN110) as a potent, selective, and in-vivo-active MAGL inhibitor. Finally, we demonstrate that MJN110 alleviates mechanical allodynia in a rat model of diabetic neuropathy, marking NHS carbamates as a promising class of MAGL inhibitors