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Lee P.,Stevens Institute of Technology | Tran K.,Stevens Institute of Technology | Chang W.,Stevens Institute of Technology | Fang Y.-L.,Stevens Institute of Technology | And 10 more authors.
Polymers for Advanced Technologies | Year: 2015

The goal of this study was to determine the efficacy of the bioactive scaffold system to initiate bone marrow stromal cell (BMSC) differentiation into osteogenic and chondrogenic lineages in various culture media compositions. In the biphasic polymeric scaffolds, the chondrogenic layer contained aligned polycaprolactone nanofibers embedded with chondroitin sulfate and hyaluronic acid, while osteogenic layer carried nano-hydroxyapatite. Many studies for in vitro testing of osteochondral scaffolds incorporate the use of complicated bioreactors or growth factors for the formation of cartilage and bone tissue, thus true efficacy of the scaffold system cannot be determined. The present study compared the effect of several media compositions consisting of osteogenic, chondrogenic components, and control basal media. Scaffolds seeded with BMSCs following 28days in vitro culture in different induction and basal media were evaluated for osteogenic and chondrogenic markers such as aggrecan, collagen type II, bone sialoprotein, alkaline phosphatase (ALP), and runt-related transcription factor 2 (Runx-2). Cartilage scaffold layer of the biphasic scaffold resulted in the expression of chondrogenic markers such as aggrecan and collagen type II by BMSCs in control and induction media compositions. The bone scaffold layer supported the expression of osteogenic markers such as ALP and Runx-2 by BMSCs in control and induction media compositions. The cartilage scaffold layer under the osteogenic induction media encouraged the growth of hypertrophic cartilage as marked by the positive expression of Runx-2. Expression of collagen type II and aggrecan on the cartilage layer in basal media was confirmed by immunostaining. These studies suggest that the bioactive scaffolds were able to support the osteogenic and chondrogenic phenotype development in the absence of growth factors and induction media. © 2015 John Wiley & Sons, Ltd.

Shelke N.B.,UCONN Health | Shelke N.B.,Institute for Regenerative Engineering | Shelke N.B.,Raymond and Beverly Sackler Center for Biomedical | Lee P.,Stevens Institute of Technology | And 11 more authors.
Polymers for Advanced Technologies | Year: 2016

Scaffolds used for soft tissue regeneration are designed to mimic the native extracellular matrix (ECM) structurally and provide adequate mechanical strength and degradation properties. Scaffold architecture, porosity, stiffness and presence of soluble factors have been shown to influence human mesenchymal stem cells (hMSCs) differentiation along neuronal lineage. The present manuscript evaluated the performance of a composite scaffold comprised of electrospun polycaprolactone (PCL) nanofiber lattice coated with sodium alginate (SA) for neural tissue engineering. The nanofiber lattice was included in the scaffold to provide tensile strength and retain suture thread on the nerve graft. Sodium alginate was used to control matrix hydrophilicity, material stiffness and controlled release of biological molecules. The effect of SA molecular weight on the composite scaffold tensile properties, hMSCs adhesion, proliferation and neurogenic differentiation was evaluated. Both random and aligned composite scaffolds showed significantly higher tensile properties as compared to PCL fiber matrix alone indicating the reinforcement of SA hydrogel into fiber lattice. Low molecular weight SA coating because of its low viscosity resulted in uniform penetration into the fiber lattice and resulted in significantly higher tensile strength as compared to high molecular weight SA. Both composite scaffolds showed a controlled SA erosion rate and lost >95% of the SA coating over a period of 10days under in vitro conditions. Composite scaffolds showed progressive hMSCs growth over 14days and resulted in significantly higher amount of DNA content (almost double on day 7 and 14) as compared to control PCL fiber matrices. Immunostaining experiments showed higher and uniform expression of the neurotropic protein S-100 on composite scaffolds containing low molecular weight SA. These composite scaffolds may be suitable for peripheral nerve regeneration. © 2016 John Wiley & Sons, Ltd.

Jaiswal D.,University of Connecticut | Jaiswal D.,Raymond and Beverly Sackler Center for Biomedical | James R.,University of Connecticut | James R.,Raymond and Beverly Sackler Center for Biomedical | And 10 more authors.
Journal of Biomedical Nanotechnology | Year: 2015

Electrospinning of water-soluble polymers and retaining their mechanical strength and bioactivity remain challenging. Volatile organic solvent soluble polymers and their derivatives are preferred for fabricating electrospun nanofibers. We report the synthesis and characterization of 2-nitrobenzyl-gelatin (N-Gelatin)-a novel gelatin Schiff base derivative-and the resulting electrospun nanofiber matrices. The 2-nitrobenzyl group is a photoactivatable-caged compound and can be cleaved from the gelatin nanofiber matrices following UV exposure. Such hydrophobic modification allowed the fabrication of gelatin and blend nanofibers with poly(caprolactone) (PCL) having significantly improved tensile properties. Neat gelatin and their PCL blend nanofiber matrices showed a modulus of 9.08±1.5 MPa and 27.61±4.3 MPa, respectively while the modified gelatin and their blends showed 15.63±2.8 MPa and 24.47±8.7 MPa, respectively. The characteristic infrared spectroscopy band for gelatin Schiff base derivative at 1560 cm-1 disappeared following exposure to UV light indicating the regeneration of free NH2 group and gelatin. These nanofiber matrices supported cell attachment and proliferation with a well spread morphology as evidenced through cell proliferation assay and microscopic techniques. Modified gelatin fiber matrices showed a 73% enhanced cell attachment and proliferation rate compared to pure gelatin. This polymer modification methodology may offer a promising way to fabricate electrospun nanofiber matrices using a variety of proteins and peptides without loss of bioactivity and mechanical strength. © 2015 American Scientific Publishers All rights reserved.

Nada A.A.,University of Connecticut Health Center | Nada A.A.,Raymond and Beverly Sackler Center for Biomedical | Nada A.A.,National Research Center of Egypt | James R.,University of Connecticut Health Center | And 11 more authors.
Polymers for Advanced Technologies | Year: 2014

The electrospinning of chitosan remains challenging due to its rigid crystalline structure, insufficient viscosity, and limited solubility in common organic solvents. This work presents a "smart" chitosan modification that allows electrospinning irrespective of molecular weight or deacetylation value and without blending with synthetic polymers. A novel derivative, namely 2-nitrobenzyl-chitosan (NB), at various molar compositions of chitosan:2-nitrobenzaldehyde (1:1 (NB-1), 1:0.5 (NB-2), 1:0.25 (NB-3)) was synthesized by the reaction between amino groups of chitosan and aldehyde groups of 2-nitrobenzaldehyde. In this Schiff base, 2-nitrobenzaldehyde protects the amine functionalities of chitosan and improves its solubility in trifluoroacetic acid. 2-nitrobenzaldehyde is a photoactivatable-caged compound that cleaves off from iminochitosan on ultraviolet exposure yielding neat chitosan. Derivatives showed improved solubility in trifluoroacetic acid and dynamic viscosities in the range of 1.34±0.7 to 12±0.5Pa·s based on the degree of substitution and concentration. Electrospinning conditions were optimized to produce bead free nanofibers in the range of 100-600nm, and concentrations beyond 12% (wt/v) for NB-1 and NB-2, and 15% (wt/v) for NB-3 were suitable. Photolysis did not alter fiber morphology; however, regenerated chitosan matrices were soluble in culture media presumably due to the presence of 2-nitrosobenzoic acid in trace amounts. Human skin fibroblasts exhibited excellent (>90%) cytocompatibility on treatment with polymer extractions from cross-linked regenerated chitosan matrices prepared to the ISO standard. Newly synthesized iminochitosan derivatives were very effective against microorganisms including bacteria (Gram-positive and Gram-negative), fungi, and yeast. These fiber matrices may serve as scaffolds for a variety of tissue healing and factor delivery applications. © 2014 John Wiley & Sons, Ltd.

Bagshaw K.R.,University of Connecticut | Hanenbaum C.L.,University of Connecticut | Carbone E.J.,Institute for Regenerative Engineering | Carbone E.J.,Raymond and Beverly Sackler Center for Biomedical | And 9 more authors.
Therapeutic Delivery | Year: 2015

Acute and chronic pain control is a significant clinical challenge that has been largely unmet. Local anesthetics are widely used for the control of post-operative pain and in the therapy of acute and chronic pain. While a variety of approaches are currently used to prolong the duration of action of local anesthetics, an optimal strategy to achieve neural blockage for several hours to days with minimal toxicity has yet to be identified. Several drug delivery systems such as liposomes, microparticles and nanoparticles have been investigated as local anesthetic delivery vehicles to achieve prolonged anesthesia. Recently, injectable responsive hydrogels raise significant interest for the localized delivery of anesthetic molecules. This paper discusses the potential of injectable hydrogels to prolong the action of local anesthetics. © 2015 Future Science Ltd

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