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AimTo study the protective effect of a fibrin scaffold toward embedded young porcine endocrine pancreatic islets from hydrogen peroxide within the context of islet encapsulation in transplantation.MethodsAfter isolation and in vitro maturation, groups of 200 young porcine islet equivalents (IEQ) were embedded in a 200 µL fibrin gel and exposed to 2 concentrations (10 and 100 µM) of hydrogen peroxide (H2O2) to investigate the ability of fibrin to protect islets against apoptotic stimuli. As a control, young porcine islets were seeded in tissue culture polystyrene (TCPS) well plates and exposed to the same H2O2 concentrations. Islet integrity, viability and function were then investigated.ResultsMorphologically, the integrity of islets embedded in fibrin gels was better preserved compared with that of islets cultured in TCPS plates, when exposed to H2O2. Immunofluorescence staining showed that insulin and glucagon expression was higher in islets cultured in fibrin. Overall, H2O2 incubation led to decreased insulin and glucagon expression. A TUNEL assay revealed elevated numbers of apoptotic cells for islets cultured in TCPS plates when compared with those embedded in fibrin. Islets cultured in TCPS plates and exposed to H2O2 had diminished ability to secrete insulin in response to glucose stimulation, whereas islets embedded in fibrin maintained their glucose responsiveness. Insulin trapped in fibrin was extracted and quantified, revealing insulin in the extract.Conclusions/interpretationFibrin has a protective effect on young porcine endocrine pancreatic islets exposed to hydrogen peroxide.

Loss in the number or function of insulin‐producing β‐cells in pancreatic islets has been associated with diabetes mellitus. Although islet transplantation can be an alternative treatment, complications such as apoptosis, ischaemia and loss of viability have been reported. The use of decellularized organs as scaffolds in tissue engineering is of interest owing to the unique ultrastructure and composition of the extracellular matrix (ECM) believed to act on tissue regeneration. In this study, a cell culture system has been designed to study the effect of decellularized porcine bladder pieces on INS‐1 cells, a cell line secreting insulin in response to glucose stimulation. Porcine bladders were decellularized using two techniques: a detergent‐containing and a detergent‐free methods. The resulting ECMs were characterized for the removal of both cells and dsDNA. INS‐1 cells were not viable on ECM produced using detergent (i.e., sodium dodecyl sulfate). INS‐1 cells were visualized following 7 days of culture on detergent‐free decellularized bladders using a cell viability and metabolism assay (MTT) and cell proliferation quantified (CyQUANT™ NF Cell Proliferation Assay). Further, glucose‐stimulated insulin secretion and immunostaining confirmed that cells were functional in response to glucose stimulation, as well as they expressed insulin and interacted with the detergent‐free produced ECM, respectively. [ABSTRACT FROM AUTHOR]

Bioadhesives are useful medical devices to help reduce postoperative complications and as adjuncts to sutures and staples in sealing wounds. Biomedical companies have been promoting research and development into new bioadhesives. As for other medical devices, translating promising candidates to market involves the need to pass through several regulatory steps, wherein their safety and effectiveness are evaluated and the proper reimbursements from payors are assessed. The regulatory procedures involve classification based on the risk factors, support studies, submission of applications to relevant authorities, procurement of certification, and finally commercialization, while keeping a track record of the post‐market data. The importance of real‐world data has been recently realized. The aim of this review is to focus on the translational goals, expectations, and necessities of medical devices focusing on the bioadhesives to be commercialized. It should aid researchers inspired to discover and market new bioadhesives in understanding the need for basic regulatory procedures behind their commercialization for medical usage, most importantly for internal medicine specifically in the United States of America, Canada, and Europe, in part. The key differences in the regulatory aspects among those are highlighted. Regulations keep changing with the introduction of new products and governmental laws. They are updated in this manuscript till March 2021. [ABSTRACT FROM AUTHOR]

FTIR microscopy is a versatile technique successfully used to probe the subcellular chemical composition of atherosclerostic arterial walls. To design new vascular substitutes that resist lipid uptake (the major cause of the phenomenon referred to as atherosclerosis-like), identifying and understanding lipid distribution within the pseudoatherosclerosed arterial prostheses is of prime importance. Until now, the amount of lipids present within arterial prostheses that had been explanted from either animals (during in vivo trials) or humans (after the failure of vascular grafts) or had been submitted to in vitro investigations could only be measured through the use of histological techniques or radioactive labeling methods. We present here a novel method to quantitatively measure the lipid concentration profile within the wall of arterial prostheses by means of Fourier transform infrared microspectroscopy. Essentially, prostheses are fixed in a 1% osmium tetraoxide aqueous solution under vacuum and radially cut with a 5-[[micro]meter] thickness with a microtome. The sections are then placed onto Ba[F.sub.2] windows and observed with a microscope attached to a FTIR spectrometer with a 30 [[micro]meter] x 50 [[micro]meter] sampling area. The lipid concentration profile is obtained by scanning the prosthesis wall from the inner to the outer surface and reporting the corresponding integrated absorbance between 2700 and 3100 [cm.sup.-1] against a calibration curve. The application of this technique constitutes the first quantitative measurement of the concentration of biological molecules within the wall of artificial arterial substitute.

Abstract Background Methylotrophic (methanol-utilizing) bacteria offer great potential as cell factories in the production of numerous products from biomass-derived methanol. Bio-methanol is essentially a non-food substrate, an advantage over sugar-utilizing cell factories. Low-value products as well as fine chemicals and advanced materials are envisageable from methanol. For example, several methylotrophic bacteria, including Methylobacterium extorquens, can produce large quantities of the biodegradable polyester polyhydroxybutyric acid (PHB), the best known polyhydroxyalkanoate (PHA). With the purpose of producing second-generation PHAs with increased value, we have explored the feasibility of using M. extorquens for producing functionalized PHAs containing C-C double bonds, thus, making them amenable to future chemical/biochemical modifications for high value applications. Results Our proprietary M. extorquens ATCC 55366 was found unable to yield functionalized PHAs when fed methanol and selected unsaturated carboxylic acids as secondary substrates. However, cloning of either the phaC1 or the phaC2 gene from P. fluorescens GK13, using an inducible and regulated expression system based on cumate as inducer (the cumate switch), yielded recombinant M. extorquens strains capable of incorporating modest quantities of C-C double bonds into PHA, starting from either C6= and/or C8=. The two recombinant strains gave poor results with C11=. The strain containing the phaC2 gene was better at using C8= and at incorporating C-C double bonds into PHA. Solvent fractioning indicated that the produced polymers were PHA blends that consequently originated from independent actions of the native and the recombinant PHA synthases. Conclusions This work constitutes an example of metabolic engineering applied to the construction of a methanol-utilizing bacterium capable of producing functionalized PHAs containing C-C double bonds. In this regard, the PhaC2 synthase appeared superior to the PhaC1 synthase at utilizing C8= as source of C-C double bonds and at incorporating C-C double bonds into PHA from either C6= or C8=. The M. ex-phaC2 strain is, therefore, a promising biocatalyst for generating advanced (functionalized) PHAs for future high value applications in various fields.