Decellularized bladder as scaffold to support proliferation and functionality of insulin-secreting pancreatic cells.

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.

Composition, host responses and clinical applications of bioadhesives.

Bioadhesives are medical devices used to join or seal tissues that have been injured or incised. They have been classified into tissue adhesives, sealants, and hemostatic agents. Bioadhesives such as FloSeal®, CoSeal®, BioGlue®, Evicel®, Tisseel®, Progel™ PALS, and TissuGlu® have been commercialized and used in clinical setting.

Overview of approval procedures for bioadhesives in the United States of America and Canada.

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.

Characterization of three-dimensional rat central nervous system culture maturation, with applications to monitor cholinergic integrity.

Studying age-related neuropathologies in vitro requires a three-dimensional (3D) culture system presenting mature phenotypes. In this study, we aimed to determine whether aged reaggregate cultures physiologically represent mature brain tissue. Results support that embryo-derived rat central nervous system (CNS) reaggregate cultures develop into mature-like tissues, comparable to in vivo maturation, including the following characteristics: (a) progressive reduction in cell proliferation (reduced anti-Ki-67 immunoreactivity), (b) progressive restriction of long neurite growth potential (as explant cultures), and (c) increased and sustained synaptic enzyme (acetylcholine esterase, AChE) activity.

The role of elastin-derived peptides in human physiology and diseases.

Once considered as inert, the extracellular matrix recently revealed to be biologically active. Elastin is one of the most important components of the extracellular matrix. Many vital organs including arteries, lungs and skin contain high amounts of elastin to assure their correct function.

Method for isolation of pancreatic blood vessels, their culture and coculture with islets of langerhans.

The only cure available for Type 1 diabetes involves the transplantation of islets of Langerhans isolated from donor organs. However, success rates are relatively low. Disconnection from vasculature upon isolation and insufficient rate of revascularization upon transplantation are thought to be a major cause, as islet survival and function depend on extensive vascularization.

Tissue and organ decellularization in regenerative medicine.

The advancement and improvement in decellularization methods can be attributed to the increasing demand for tissues and organs for transplantation. Decellularized tissues and organs, which are free of cells and genetic materials while retaining the complex ultrastructure of the extracellular matrix (ECM), can serve as scaffolds to subsequently embed cells for transplantation. They have the potential to mimic the native physiology of the targeted anatomic site.

Multiple-Condition Analysis in a Retrievable Subcutaneous Animal Model for Drug Screening on Full Pancreatic Tissue Digest.

In vitro in vivo

Insulin secretion kinetics from single islets reveals distinct subpopulations.

Type II diabetes progresses with inadequate insulin secretion and prolonged elevated circulating glucose levels. Also, pancreatic islets isolated for transplantation or tissue engineering can be exposed to glucose over extended timeframe. We hypothesized that isolated pancreatic islets can secrete insulin over a prolonged period of time when incubated in glucose solution and that not all islets release insulin in unison.

Decellularized pancreas as a native extracellular matrix scaffold for pancreatic islet seeding and culture.

Diabetes mellitus involves the loss of function and/or absolute numbers of insulin-producing β cells in pancreatic islets. Islet transplantation is currently being investigated as a potential cure, and advances in tissue engineering methods can be used to improve pancreatic islets survival and functionality. Transplanted islets experience anoikis, hypoxia, and inflammation-mediated immune response, leading to early damage and subsequent failure of the graft.

A factorial design to identify process parameters affecting whole mechanically disrupted rat pancreata in a perfusion bioreactor.

Few studies report whole pancreatic tissue culture, as it is a difficult task using traditional culture methods. Here, a factorial design was used to investigate the singular and combinational effects of flow, dissolved oxygen concentration (D.O.

Quartz crystal microbalance as an assay to detect anti-drug antibodies for the immunogenicity assessment of therapeutic biologics.

Because of their biological origins, therapeutic biologics can trigger an unwanted deleterious immune response with some patients. The immunogenicity of therapeutic biologics can affect drug efficacy and patient safety by the production of circulating anti-drug antibodies (ADA). In this study, quartz crystal microbalance (QCM) was developed as an assay to detect ADA.

Biomimetic Surfaces Supporting Dissociated Pancreatic Islet Cultures.

This study describes a method to screen biomimetic surfaces based on intracellular insulin content of either fully or partly dissociated primary endocrine islet tissue. It is challenging to maintain endocrine pancreatic islets and more so, dissociated ones. Physiological activity of isolated islet cells in vitro declines due to loss of cell-to-cell and cell-to-extracellular matrix interactions.

An In-situ glucose-stimulated insulin secretion assay under perfusion bioreactor conditions.

Perfusion bioreactors, unlike traditional in vitro cell culture systems, offer stringent control of physiological parameters such as pH, flow, temperature, and dissolved oxygen concentration which have been shown to have an impact on cellular behaviour and viability. Due to the relative infancy and the growing interest in these in vitro culture systems, detection methods to monitor cell function under dynamic perfusion bioreactor conditions remains one of the main challenges. In this study, INS-1 cells, a cell line which exhibit glucose-stimulated insulin secretion, were embedded in fibrin and cultured under perfusion bioreactor conditions for 48 h and then exposed to either a high-, or low-glucose concentration for 24 h.

Real-time label-free detection and kinetic analysis of Etanercept-Protein A interactions using quartz crystal microbalance.

A quartz crystal microbalance (QCM) was constructed to assess if such a biosensor has value as a complementary real-time label-free analysis platform for the biopharmaceutical industry. This was achieved through modifying QCM crystals with a low-fouling carboxymethyl-dextran layer bearing Protein A, and then injecting solutions containing Etanercept (i.e.

Intracellular insulin quantification by cell-ELISA.

Current methods of monitoring insulin in culture are limited to soluble insulin (secretions or lysates) or synthetic gene reporter analyses. We present an insulin-specific cell enzyme-linked immunosorbent assay (cell-ELISA) to assess relative intracellular insulin protein content of adherent cultures, normalized to cell density with further immunocytochemical verification of insulin-expressing cells within identical cultures. The protocol was optimized and validated using an insulin-expressing cell line (INS-1) by confirming direct relations between intracellular insulin content and insulin-expressing cell density, in a glucose exposure-dependent manner.

Young porcine endocrine pancreatic islets cultured in fibrin show improved resistance toward hydrogen peroxide.

Aim: To 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.

Methods: After 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.

Laminin receptor 37/67LR regulates adhesion and proliferation of normal human intestinal epithelial cells.

Interactions between the cell basal membrane domain and the basement membrane are involved in several cell functions including proliferation, migration and differentiation. Intestinal epithelial cells can interact with laminin, a major intestinal basement membrane glycoprotein, via several cell-surface laminin-binding proteins including integrin and non-integrin receptors. The 37/67kDa laminin receptor (37/67LR) is one of these but its role in normal epithelial cells is still unknown.

INS-1 cell glucose-stimulated insulin secretion is reduced by the downregulation of the 67 kDa laminin receptor.

Understanding β cell-extracellular matrix (ECM) interactions can advance our knowledge of the mechanisms that control glucose homeostasis and improve culture methods used in islet transplantation for the treatment of diabetes. Laminin is the main constituent of the basement membrane and is involved in pancreatic β cell survival and function, even enhancing glucose-stimulated insulin secretion. Most of the studies on cell responses towards laminin have focused on integrin-mediated interactions, while much less attention has been paid on non-integrin receptors, such as the 67 kDa laminin receptor (67LR).

A 3D cell culture system: separation distance between INS-1 cell and endothelial cell monolayers co-cultured in fibrin influences INS-1 cells insulin secretion.

The aim of this study was to develop an in vitro cell culture system allowing studying the effect of separation distance between monolayers of rat insulinoma cells (INS-1) and human umbilical vein endothelial cells (HUVEC) co-cultured in fibrin over INS-1 cell insulin secretion. For this purpose, a three-dimensional (3D) cell culture chamber was designed, built using micro-fabrication techniques and validated. The co-culture was successfully carried out and the effect on INS-1 cell insulin secretion was investigated.

Solution composition impacts fibronectin immobilization on carboxymethyl-dextran surfaces and INS-1 insulin secretion.

It is shown that solution composition during immobilization plays a critical role in the properties of fibronectin (FN) surfaces and their bioactivity towards insulinoma (INS-1) cell function. X-ray photoelectron spectroscopy revealed FN grafting onto low-fouling carboxymethyl-dextran (CMD) surfaces was successful with solutions composed of 10 μM CaCl(2), 10 μM MgCl(2), 10 μM MnCl(2), and 10 μM and 1mM NaCl, but unsuccessful with those made of 150 mM NaCl or 1× PBS. Circular dichroism and photon correlation spectroscopy revealed that regardless of solution composition, no measurable differences in free FN conformation prevail.

Positron emission tomography detection of human endothelial cell and fibroblast monolayers: effect of pretreament and cell density on 18FDG uptake.

Background: The non-destructive assessment and characterization of tridimensional (3D) cell and tissue constructs in bioreactors represents a challenge in tissue engineering. Medical imaging modalities, which can provide information on the structure and function of internal organs and tissues in living organisms, have the potential of allowing repetitive monitoring of these 3D cultures in vitro. Positron emission tomography (PET) is the most sensitive non-invasive imaging modality, capable of measuring picomolar amounts of radiolabeled molecules.

A model for cellulase production from Trichoderma reesei in an airlift reactor.

A mathematical model for cellulase production by Trichoderma reesei RUT-C30 grown in a cellulose medium with lactose as fed batch in an airlift reactor is proposed. To describe adequately the mass transfer between the air bubbles and the broth, it uses computational fluid dynamics (CFD) including multiphase Eulerian-Eulerian formulation, with a detailed description of the bubble size distribution through the use of the population balance model (PBM) and the class method (CM). The kinetics of the biomass growth is further coupled to the fluid flow conditions using partial differential equations for all the species involved, providing detailed information of important reactor conditions such as the distribution of oxygen, cellulose, and the shear stress within the reactor over the entire period of fermentation.