Electrosprayed Montelukast/poly (lactic-co-glycolic acid) particle based coating: A new therapeutic approach towards the prevention of in-stent restenosis.

UNLABELLED: Drug-eluting stents (DESs), have shown promising results in prevention of in-stent restenosis after percutaneous coronary intervention (PCI). The elevated level of leukotrienes (LTs) detected in injured arteries after PCI, together with the potential role of LTs in inflammatory cascades and structural alterations in arterial wall provides the rationale for development of therapeutic strategies for prevention of in-stent restenosis using LTs receptor antagonists. Montelukast (MK) is a selective cysLT1 receptor antagonist, with anti-inflammatory and anti-proliferative properties, which has been used for treatment of various diseases. Here, we report on the fabrication of MK/PLGA particles by electrospraying, aiming towards the development of particle based coating of DESs. The electrosprayed particles incorporated with 3% and 6% w/w MK exhibited fairly spherical shape with smooth surfaces and narrow size distribution. Sustained release of MK for up to 40days was obtained for both formulations, with higher initial burst release and drug release rate for the particles with higher drug loading. The LTD4 induced proliferation and migration of human coronary artery smooth muscle cells (HCASMCs) by 35% and 85%, respectively, which was substantially antagonized using MK incorporated particles. Nevertheless, MK antagonism preserved the normal proliferation and migration of human coronary artery endothelial cells (HCAECs). Moreover, MK antagonism inhibited the LTD4 induced phenotypic transition of HCASMCs from contractile to synthetic type. The electrosprayed MK-PLGA particles can be employed as a coating for DESs to inhibit the formation of neointimal hyperplasia responsible for in-stent restenosis, yet preserve the healing rate of the stented vessel. STATEMENT OF SIGNIFICANT: Montelukast (MK) is a selective cysLT1 receptor antagonist, with anti-inflammatory and anti-proliferative properties. The LTD4 induced proliferation and migration of human coronary artery smooth muscle cells by 35% and 85%, respectively, which was substantially antagonized using MK incorporated particles. MK antagonism preserved the normal proliferation and migration of human coronary artery endothelial cells. The MK antagonism inhibited the phenotypic transition of human coronary artery smooth muscle cells from contractile to synthetic one induced by LTD4. The electrosprayed MK-PLGA particles can be employed as coating for DESs to inhibit formation of neointimal hyperplasia, responsible for in-stent restenosis.

A mathematical model for analyzing the elasticity, viscosity, and failure of soft tissue: comparison of native and decellularized porcine cardiac extracellular matrix for tissue engineering.

The clinical success of tissue-engineered constructs commonly requires mechanical properties that closely mimic those of the human tissue. Determining the viscoelastic properties of such biomaterials and the factors governing their failure profiles, however, has proven challenging, although collecting extensive data regarding their tensile behavior is straightforward. The easily calculated Young's modulus remains the most reported mechanical measure, regardless of its limitations, even though single-relaxation-time (SRT) models can provide much more information, which remain scarce due to a lack of manageable tools for implementing these models. We developed an easy-to-use algorithm for applying the Zener SRT model and determining the elastic moduli, viscosity, and failure profiles of materials under different mechanical tests in a user-independent manner. The algorithm was validated on the data resulting from tensile tests on native and decellularized porcine cardiac tissue, previously suggested as a promising scaffold material for cardiac tissue engineering. This analysis yields new and more accurate measurements such as the elastic moduli and viscosity, the model's relaxation time, and information on the factors governing the materials' failure profiles. These measurements indicate that the viscoelasticity and strength of the decellularized acellular extracellular matrix (ECM) are similar to those of native tissue, although its elasticity and apparent viscosity are higher. Nonetheless, reseeding and culturing the ECM with mesenchymal stem cells was shown to partially restore the mechanical properties lost after decellularization. We propose this algorithm as a platform for soft-tissue analysis that can provide comparable and unbiased measures for characterizing viscoelastic biomaterials commonly used in tissue engineering.

Effect of electrospun poly(D,L-lactide) fibrous scaffold with nanoporous surface on attachment of porcine esophageal epithelial cells and protein adsorption.

Electrospun scaffolds have been increasingly used in tissue engineering applications due to their size-scale similarities with native extracellular matrices. Their inherent fibrous features may be important in promoting cell attachment and proliferation on the scaffolds. In this study, we explore the technique of fabricating electrospun fibers with nano-sized porous surfaces and investigate their effects on the attachment of porcine esophageal epithelial cells (PEECs). Porosity was introduced in electrospun poly(D,L-lactide) fibers by creating vapor-induced phase separation conditions during electrospinning. The nanoporous fiber scaffolds were mechanically weaker than the conventional solid fiber scaffolds and solvent-cast films of the same polymer. However, the nanoporosity of the fibers was found to enhance the levels of adsorbed protein from a dilute solution of fetal bovine serum. The amount of protein adsorbed by nanoporous fiber scaffolds was approximately 80% higher than the solid fiber scaffolds. This corresponds to an estimated 62% increase in surface area of the porous fibers than the solid fibers. By comparison, the solvent-cast films adsorbed low levels of protein from the FBS solution. In addition, the porous fibers were found to be advantageous in enhancing initial cell attachment as compared with the solid fibers and solvent-cast films. It was observed that nanoporous fiber scaffolds seeded with PEECs had significantly greater number of viable cells attached than the solid fiber scaffolds after 10 and 24 h in culture. Hence, our results indicate that nanosized porous surfaces on electrospun fibers enhance both protein adsorption and cell attachment. These findings provide a method to improve cell-matrix interactions of electrospun scaffolds for tissue engineering applications.

Protein bonding on biodegradable poly(L-lactide-co-caprolactone) membrane for esophageal tissue engineering.

A biodegradable and flexible poly(L-lactide-co-caprolactone) (PLLC) copolymer was synthesized and surface modification has been performed aiming at application as a scaffold in esophageal tissue engineering. The PLLC membrane surface was aminolyzed by 1,6-hexanediamine to introduce free amino groups. Using these amino groups as bridges, fibronectin and collagen were subsequently bonded with glutaraldehyde as a coupling agent. The presence of free amino groups on the aminolyzed PLLC surface was quantified using fluorescamine analysis method, which revealed that the surface NH2 density increased and eventually saturated with increasing 1,6-hexanediamine concentration or reaction time. X-ray photoelectron spectroscopy (XPS) confirmed the presence of both proteins separately on the modified PLLC surface. Water contact angle measurements evaluate the wettability of modified and unmodified PLLC surfaces. Protein-bonded surface presented more hydrophilic and homogeneous, yet PLLC can also adsorb some protein molecules. In vitro long-term (12d) culture of porcine esophageal cells proved that fibronectin- and collagen-modified PLLC surface (denoted PLLC-Fn and PLLC-Col, respectively) can more effectively support the growth of smooth muscle cells and epithelial cells; both modified and unmodified PLLC support fibroblasts growth. Mitochondrial activity assay and cell morphology observation indicate that the PLLC-Fn surface is more favorable to epithelium regeneration than PLLC-Col. These culture results provide much valuable information for our subsequent research on the construction of artificial scaffolds with esophageal function. Fibronectin-integrated PLLC will be a good candidate scaffold to support the growth of all types of esophageal cells.