Exploiting the Features of Short Peptides to Recognize Specific Cell Surface Markers.

Antibodies are the macromolecules of choice to ensure specific recognition of biomarkers in biological assays. However, they present a range of shortfalls including a relatively high production cost and limited tissue penetration. Peptides are relatively small molecules able to reproduce sequences of highly specific paratopes and, although they have less biospecificity than antibodies, they offer advantages like ease of synthesis, modifications of their amino acid sequences and tagging with fluorophores and other molecules required for detection.

Magnetic separation and concentration of Aβ 1-42 molecules dispersed at the threshold concentration for Alzheimer's disease diagnosis in clinically-relevant volumes of sample.

Background: Alzheimer's disease (AD) is the leading cause of dementia and loss of autonomy in the elderly, implying a progressive cognitive decline and limitation of social activities. The progressive aging of the population is expected to exacerbate this problem in the next decades. Therefore, there is an urgent need to develop quantitative diagnostic methodologies to assess the onset the disease and its progression especially in the initial phases.

The Real-Time Validation of the Effectiveness of Third-Generation Hyperbranched Poly(ɛ-lysine) Dendrons-Modified KLVFF Sequences to Bind Amyloid-β Peptides Using an Optical Waveguide Light-Mode Spectroscopy System.

The aggregation of cytotoxic amyloid peptides (Aβ) is widely recognised as the cause of brain tissue degeneration in Alzheimer's disease (AD). Indeed, evidence indicates that the deposition of cytotoxic Aβ plaques formed through the gradual aggregation of Aβ monomers into fibrils determines the onset of AD. Thus, distinct Aβ inhibitors have been developed, and only recently, the use of short linear peptides has shown promising results by either preventing or reversing the process of Aβ aggregation.

Development of scaffold-free vascularized pancreatic beta-islets in vitro models by the anchoring of cell lines to a bioligand-functionalized gelatine substrate.

Bioengineered pancreatic β-islets have been widely advocated for the research and treatment of diabetes by offering both suitable cell culture models for the study of the pathology and the testing of new drugs and a therapy in those patients no longer responding to insulin administration and as an alternative to the shortage of donors for organ and islet transplantation. Unlike most of the studies published so far where pancreatic islets of pancreatic β-cells are encapsulated in hydrogels, this study demonstrate the formation of bioengineered pancreatic islets through cell anchoring to a gelatine-based biomaterial, PhenoDrive-Y, able to mimic the basement membrane of tissues. Through simple culture conditions, PhenoDrive-Y led human pancreatic β-cell lines and human umbilical endothelial cell lines to form organized structures closely resembling the natural vascularized pancreatic islets.

A multistep in vitro hemocompatibility testing protocol recapitulating the foreign body reaction to nanocarriers.

The development of drug nanocarriers based on polymeric, lipid and ceramic biomaterials has been paving the way to precision medicine, where the delivery of poorly soluble active compounds and personalized doses are made possible. However, the nano-size character of these carriers has been demonstrated to have the potential to elicit pathways of the host response different from those of the same biomaterials when engineered as larger size implants and of the drugs when administered without a carrier. Therefore, a specific regulatory framework needs to be made available that can offer robust scientific insights and provide safety data by reliable tests of these novel nano-devices.

A Substrate-Mimicking Basement Membrane Drives the Organization of Human Mesenchymal Stromal Cells and Endothelial Cells Into Perivascular Niche-Like Structures.

Extracellular matrix-derived products (e.g. Matrigel) are widely used for cell cultures both as two-dimensional (2D) substrates and as three-dimensional (3D) encapsulation gels because of their ability to control cell phenotypes through biospecific cues.

A comparative in vitro study of the effect of biospecific integrin recognition processes and substrate nanostructure on stem cell 3D spheroid formation.

The in vitro study of the properties of the human mesenchymal stem cells as well as their manipulation in culture for clinical purposes depends on the elimination of artefacts caused by the lack of their natural environment. It is now widely accepted that mesenchymal stem cells should be studied when they are organised as 3D spheroids rather than fibroblast-like colonies. Although this can be achieved with the use of some extracellular matrix proteins or by non-adherent conditions these suffer of significant limitations.

Carboxybetaine-modified succinylated chitosan-based beads encourage pancreatic β-cells (Min-6) to form islet-like spheroids under in vitro conditions.

In vitro, pancreatic β-cells tend to reduce their ability to aggregate into islets and lose insulin-producing ability, likely due to insufficient cell-cell and cell-matrix interactions that are essential for β-cell retention, viability and functionality. In response to these needs, surfaces of succinylated chitosan-based beads (NSC) were modified with zwitterionic carboxy-betaine (CB) moieties, a compatible osmolyte known to regulate cellular hydration state, and used to promote the formation of β-cell spheroids using a conventional 2D cell culture technique. The NSC were synthesised by ionic gelation and surface-functionalised with CB using carbodiimide chemistry.

Hyperbranched poly(ϵ-lysine) substrate presenting the laminin sequence YIGSR induces the formation of spheroids in adult bone marrow stem cells.

Unlike the fibroblast-like cells formed upon monolayer culture of human mesenchymal stem cells, the natural stem cell niche of the bone marrow and other types of tissues favours the formation of 3-dimensional (3D) cell clusters. The structuring and biological activity of these clusters are regulated by the contacts established by cells with both the basement membrane and neighbour cells and results in their asymmetric division and the consequent maintenance of both a stem population and a committed progeny. The present work demonstrates the potential of a synthetic substrate to mimic the stem cell niche in vitro.

Vascular Endothelial Growth Factor Sequestration Enhances In Vivo Cartilage Formation.

Autologous chondrocyte transplantation for cartilage repair still has unsatisfactory clinical outcomes because of inter-donor variability and poor cartilage quality formation. Re-differentiation of monolayer-expanded human chondrocytes is not easy in the absence of potent morphogens. The Vascular Endothelial Growth Factor (VEGF) plays a master role in angiogenesis and in negatively regulating cartilage growth by stimulating vascular invasion and ossification.

Anti-angiogenic potential of VEGF blocker dendron loaded on to gellan gum hydrogels for tissue engineering applications.

Damage of non-vascularised tissues such as cartilage and cornea can result in healing processes accompanied by a non-physiological angiogenesis. Peptidic aptamers have recently been reported to block the vascular endothelial growth factor (VEGF). However, the therapeutic applications of these aptamers are limited due to their short half-life in vivo.

In vivo biofunctional evaluation of hydrogels for disc regeneration.

Purpose: Regenerative strategies aim to restore the original biofunctionality of the intervertebral disc. Different biomaterials are available, which might support disc regeneration. In the present study, the prospects of success of two hydrogels functionalized with anti-angiogenic peptides and seeded with bone marrow derived mononuclear cells (BMC), respectively, were investigated in an ovine nucleotomy model.

Synthesis, characterisation and in vitro anti-angiogenic potential of dendron VEGF blockers.

To overcome the lack of in vivo stability of certain peptides used in cancer treatment and to increase their retention time in the extracellular matrix of the target tissue, the anti-angiogenic WHLPFKC sequence is synthesised at the uppermost branching generation of a poly(ε-lysine) dendron. The root of these dendrons is designed to interact preferentially with macromolecules of the extracellular matrix, whilst the uppermost branching generation of the dendron increased the exposed density of the bioactive peptide. Bioactivity testing of the blockers is performed on HUVECs.