Nano/microparticle incorporated chitosan fibers as tissue engineering scaffolds

[Excerpt] The aim of this study was to develop a bone tissue engineering scaffold with an inherent bone morphogenetic proteins BMP-2 and BMP-7 sequential delivery system. BMPs were encapsulated in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(lactic acid-co-glycolic acid) (PLGA) nano/microparticules which are then introduced to a chitosan matrix by two methods: embedding in the chitosan fibers and then forming the scaffold or by forming the chitosan scaffold and then introducing the nano/microparticules. [...]info:eu-repo/semantics/publishedVersio

Effect of double growth factor release on cartilage tissue engineering

The effects of double release of insulin-like growth factor I (IGF-I) and growth factor β1 (TGF-β1) from nanoparticles on the growth of bone marrow mesenchymal stem cells and their differentiation into cartilage cells were studied on PLGA scaffolds. The release was achieved by using nanoparticles of poly(lactic acid-co-glycolic acid) (PLGA) and poly(N-isopropylacrylamide) (PNIPAM) carrying IGF-I and TGF-β1, respectively. On tissue culture polystyrene (TCPS), TGF-β1 released from PNIPAM nanoparticles was found to have a significant effect on proliferation, while IGF-I encouraged differentiation, as shown by collagen type II deposition. The study was then conducted on macroporous (pore size 200-400μm) PLGA scaffolds. It was observed that the combination of IGF-I and TGF-β1 yielded better results in terms of collagen type II and aggrecan expression than GF-free and single GF-containing applications. It thus appears that gradual release of a combination of growth factors from nanoparticles could make a significant contribution to the quality of the engineered cartilage tissue. © 2011 John Wiley & Sons, Ltd

Use and efficacy of bone morphogenetic proteins in fracture healing

Signal transduction in aging related disease

Influence of controlled-pH and uncontrolled-pH operations on recombinant benzaldehyde lyase production by Escherichia coli

To select the host microorganism having the highest benzaldehyde lyase (BAL) production capacity, pUC 18::bal gene was transferred into four Escherichia coli strains. As the highest enzyme activity was obtained with E. coli K12 (ATCC 10798) carrying pUC18::bal gene, BAL production medium was designed for K 12. Using the designed medium containing 8.0 kg m(-3) glucose, 5.0 kg m(-3) (NH4)(2)HPO4 and the salt solution, the effects of uncontrolled-pH and controlled-pH operations were investigated at uncontrolled-pH pH(UC) 7.2 and controlled-pH values pH(C) 5.0, 6.4, 6.7, 7.0 7.2 and 7.8 in 3.0 dm(3) bioreactor systems with a V-R = 1.65 dm(3) working volume at the air inlet rate of Q(o)/V-R = 0.5 vvm and agitation rate of N= 500 min(-1). The uncontrolled-pH (pHuc 7.2) operation produced the highest cell concentration and BAL activity as C-X = 2.3 kg m(-3) and A = 860 U cm(-3). respectively. Among the controlled-pH operations, the highest cell concentration and enzyme activity were obtained at pH(C) 7.0 operation, respectively, as C-X = 2. 1 kg m(-3) and A = 775 U cm(-3). The accumulation of the metabolic by-product acetic acid and the total organic acid concentrations were the highest at pHc 7.2 and 7.8 operations. On the other hand, there was no significant difference in the acetic acid concentration profiles of pHc 5.0. 6.4, 6.7 and 7.0 operations; however, the highest total organic acid concentration was attained at pHC 5.0 because of the lactic acid excretion, and the lowest total organic acid was obtained at pH(C) 6.7. K(L)a values varied between 0.01 and 0.03 s(-1). To compare the mass transfer and biochemical reaction rates, the maximum possible oxygen utilization rate, possible mass transfer rate, Damkohler number, and effectiveness factor, were also calculated. Damkohler number increased with the cultivation time indicating that mass transfer resistances were becoming more effective than biochemical reaction resistances. The yield and maintenance coefficients as well as the kinetic constants for BAL production process were also reported. (c) 2005 Elsevier Inc. All rights reserved

Sequential BMP-2/BMP-7 delivery from polyester nanocapsules

The aim of this study was to develop a nanosized, controlled growth factor release system to incorporate into tissue engineering scaffolds and thus activate the cells seeded in the scaffold. Nanocapsules of poly(lactic acid-co-glycolic acid) (PLGA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were loaded with the bone morphogenetic proteins BMP-2 and BMP-7, respectively, and with bovine serum albumin (BSA), the model protein. BSA-loading efficiency and release kinetics were used to determine the most appropriate nanocapsule pair to achieve the delivery of growth factors in a sequential manner, as occurs in natural processes. BSA-encapsulation efficiency was highest when the polymer concentration used in the preparation of PLGA and PHBV nanocapsules was 10% (w/v) (84.75% and 16.72%, respectively). Release of BSA was faster from PEGA than it was from PHBV. Based on the encapsulation efficiency and release data, 10% PLGA and 1.0% PHBV nanocapsules were chosen to provide the early BMP-2 and later BMP-7 release, respectively. Simultaneous, sequential delivery and individual release of the BMPs were studied for 7, 14, and 21 days, using rat bone marrow mesenchymal stem cells. Individual BMP-2 release suppressed cell proliferation while providing higher alkaline phosphatase activity with respect to BMP-7. The sequential delivery of BMP-2 and BMP-7 provided slightly lower proliferation than did simultaneous delivery, but the highest alkaline phosphatase activity of all indicated a synergistic effect on the osteogenic differentiation of mesenchymal stem cells caused by the use of the two growth factors in a sequential fashion. (C) 2009 Wiley Periodicals, Inc. J Biomed Mater Res 93A: 528-536, 201

Chitosan-based wet-spun scaffolds for bioactive agent delivery

Use of scaffolds both as supporting materials at defect site and delivery vehicles for bioactive agents is a commonly employed strategy to aid in tissue repair and regeneration. In this study, fibrous meshes of chitosan were prepared by wet spinning and coated with alginate. BSA as a model protein and gentamicin as a model antibiotic were incorporated into the scaffolds in multiple loading models and their release kinetics were studied. The effects of structural form of scaffold and properties of bioactive agents on release profiles were evaluated. Our results suggest that, designed scaffolds are potential candidates for tissue engineering with the feature of controlled bioactive agent delivery. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3759-3769, 2013 Copyright © 2013 Wiley Periodicals, Inc