Articular cartilage regeneration with a microgel as a support biomaterial. A rabbit knee model.

Articular cartilage has limited regenerative capacity, so focal lesions generate mechanical stress in the joint that induces an aggravation of the damage, which ultimately leads to osteoarthritis. We recently suggested the use of microgels at the site of the cartilage defect, as a support material, to generate a biomechanical environment where pluripotent cells differentiate towards the hyaline cartilage phenotype. Here we propose a chondral regeneration strategy based on subchondral bone injury, and filling the defect site with an agglomerate of two types of microspheres, some rigid made of a biodegradable polyester (40 μm mean diameter), and others with a gel consistency made of platelet-rich plasma obtained from circulating blood (70-110 μm diameter).

Mesenchymal Stem Cells Cultured in a 3D Microgel Environment Containing Platelet-Rich Plasma Significantly Modify Their Chondrogenesis-Related miRNA Expression.

The aim of this work is to study the effect of platelet factors on the differentiation of mesenchymal stem cells (MSCs) to hyaline cartilage chondrocytes in a three-dimensional environment. MSCs were cultured in a microgel environment with a chondrogenic medium. The microgel consisted of microspheres that combine gelatin and platelet-rich plasma (PRP).

Microfluidic Processing of Piezoelectric and Magnetic Responsive Electroactive Microspheres.

Poly(vinylidene fluoride) (PVDF) combined with cobalt ferrite (CFO) particles is one of the most common and effective polymeric magnetoelectric composites. Processing PVDF into its electroactive phase is a mandatory condition for featuring electroactive behavior and specific (post)processing may be needed to achieve this state, although electroactive phase crystallization is favored at processing temperatures below 60 °C. Different techniques are used to process PVDF-CFO nanocomposite structures into microspheres with high CFO dispersion, with microfluidics adding the advantages of high reproducibility, size tunability, and time and resource efficiency.

Covalently Grafted Peptides to Decellularized Pericardium: Modulation of Surface Density.

The covalent functionalization of synthetic peptides allows the modification of different biomaterials (metallic, polymeric, and ceramic), which are enriched with biologically active sequences to guide cell behavior. Recently, this strategy has also been applied to decellularized biological matrices. In this study, the covalent anchorage of a synthetic peptide (REDV) to a pericardial matrix decellularized via Schiff base is realized starting from concentrated peptide solutions (10 M and 10 M).

Stability of Biomimetically Functionalised Alginate Microspheres as 3D Support in Cell Cultures.

Alginate hydrogels can be used to develop a three-dimensional environment in which various cell types can be grown. Cross-linking the alginate chains using reversible ionic bonds opens up great possibilities for the encapsulation and subsequent release of cells or drugs. However, alginate also has a drawback in that its structure is not very stable in a culture medium with cellular activity.

Elastin-Plasma Hybrid Hydrogels for Skin Tissue Engineering.

Dermo-epidermal equivalents based on plasma-derived fibrin hydrogels have been extensively studied for skin engineering. However, they showed rapid degradation and contraction over time and low mechanical properties which limit their reproducibility and lifespan. In order to achieve better mechanical properties, elasticity and biological properties, we incorporated a elastin-like recombinamer (ELR) network, based on two types of ELR, one modified with azide (SKS-N) and other with cyclooctyne (SKS-Cyclo) chemical groups at molar ratio 1:1 at three different SKS (serine-lysine-serine sequence) concentrations (1, 3, and 5 wt.

Effect of electrical stimulation on chondrogenic differentiation of mesenchymal stem cells cultured in hyaluronic acid - Gelatin injectable hydrogels.

Electrical stimulation (ES) has provided enhanced chondrogenesis of mesenchymal stem cells (MSCs) cultured in micro-mass without the addition of exogenous growth factors. In this study, we demonstrate for the first time that ES of MSCs encapsulated in an injectable hyaluronic acid (HA) - gelatin (GEL) mixture enhances the chondrogenic potential of the hydrogel. Samples were stimulated for 21 days with 10 mV/cm at 60 kHz, applied for 30 min every 6 h a day.

Injectable chitosan-hydroxyapatite hydrogels promote the osteogenic differentiation of mesenchymal stem cells.

Injectable hydrogels have emerged as promising biomaterials for tissue engineering applications. The goal of this study was to evaluate the potential of a pH-responsive chitosan-hydroxyapatite hydrogel to be used as a three-dimensional support for encapsulated mesenchymal stem cells (MSCs) osteogenic differentiation. In vitro enzymatic degradation of the hydrogel, during 28 days of incubation, in simulated physiological condiditons, was characterized by swelling measurements, molecular weight determination and SEM analysis of hydrogel microstructure.

Influence of oxygen levels on chondrogenesis of porcine mesenchymal stem cells cultured in polycaprolactone scaffolds.

Chondrogenesis of mesenchymal stem cells (MSCs) is known to be regulated by a number of environmental factors, including local oxygen levels. The hypothesis of this study is that the response of MSCs to hypoxia is dependent on the physical and chemical characteristics of the substrate used. The objective of this study was to explore how different modifications to polycaprolactone (PCL) scaffolds influenced the response of MSCs to hypoxia.

Porous polylactic acid-silica hybrids: preparation, characterization, and study of mesenchymal stem cell osteogenic differentiation.

A novel approach to reinforce polymer porous membranes is presented. In the prepared hybrid materials, the inorganic phase of silica is synthesized in-situ and inside the pores of aminolyzed polylactic acid (PLA) membranes by sol-gel reactions using tetraethylorthosilicate (TEOS) and glycidoxypropyltrimethoxysilane (GPTMS) as precursors. The hybrid materials present a porous structure with a silica layer covering the walls of the pores while GPTMS serves also as coupling agent between the organic and inorganic phase.

Comparative study of PCL-HAp and PCL-bioglass composite scaffolds for bone tissue engineering.

The aim of this work is to compare the effect of hydroxyapatite (HAp) or bioglass (BG) nanoparticles in a polycaprolactone composite scaffold aimed to bone regeneration. To allow a comparison of the influence of both types of fillers, scaffolds made of PCL or composites containing up to 20 % by weight HAp or BG were obtained. Scaffolds showed acceptable mechanical properties for its use and high interconnected porosity apt for cellular colonization.

Different hyaluronic acid morphology modulates primary articular chondrocyte behavior in hyaluronic acid-coated polycaprolactone scaffolds.

Scaffolds for cartilage tissue engineering should promote both adequate biomechanical environment and chondrogenic stimulation. Hyaluronic acid (HA) has been used in cartilage engineering for its chondrogenic and chondroprotective properties, nevertheless its mechanical properties are limited. Influence of HA microstructure in chondrocyte response has not been addressed yet.