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Medscape

Polymer nanoparticles: Preparation techniques and size-control parameters

Bioactive modification of poly(ethylene glycol) hydrogels for tissue engineering

This article summarizes the recent progress in the design and synthesis of hydrogels as tissue-engineering scaffolds. Hydrogels are attractive scaffolding materials owing to their highly swollen network structure, ability to encapsulate cells and bioactive molecules, and efficient mass transfer. Various polymers, including natural, synthetic and natural/synthetic hybrid polymers, have been used to make hydrogels via chemical or physical crosslinking. Recently, bioactive synthetic hydrogels have emerged as promising scaffolds because they can provide molecularly tailored biofunctions and adjustable mechanical properties, as well as an extracellular matrix-like microenvironment for cell growth and tissue formation. This article addresses various strategies that have been explored to design synthetic hydrogels with extracellular matrix-mimetic bioactive properties, such as cell adhesion, proteolytic degradation and growth factor-binding.

Design properties of hydrogel tissue-engineering scaffolds

Modulation of cell adhesion, proliferation and differentiation on materials designed for body implants.

Osteogenic differentiation and mineralization of bone marrow stromal (BMS) cells depends on the cells’ interactions with bioactive peptides associated with the matrix proteins. The RGD peptides of ECM proteins interact with BMS cells through integrin surface receptors to facilitate cell spreading and adhesion. The BMP peptide corresponding to residues 73−92 of bone morphogenetic protein-2 promotes differentiation and mineralization of BMS cells. The objective of this work was to investigate the effects of RGD and BMP peptides, grafted to a hydrogel substrate, on osteogenic differentiation and mineralization of BMS cells. RGD peptide was acrylamide-terminated by reacting acrylic acid with the N-terminal amine group of the peptide to produce the functionalized Ac-GRGD peptide. The PEGylated BMP peptide was reacted with 4-carboxybenzenesulfonazide to produce an azide functionalized Az-mPEG-BMP peptide. Poly (lactide-co-ethylene oxide-co-fumarate) (PLEOF) macromer was cross-linked with Ac-GRGD peptide and pro...

Effect of grafting RGD and BMP-2 protein-derived peptides to a hydrogel substrate on osteogenic differentiation of marrow stromal cells.

The fibrillar structure and sub-micron diameter of electrospun nanofibers can be used to reproduce the morphology and structure of the natural extracellular matrix (ECM). The objective of this work was to investigate the effect of fiber alignment on osteogenic differentiation of bone marrow stromal (BMS) cells. Random and aligned poly(l-lactide) (PLLA) nanofibers were produced by collecting the spun fibers on a stationary plate and a rotating wheel, respectively, as the ground electrode. Morphology and alignment of the BMS cells seeded on the fibers were characterized by SEM. The effect of fiber orientation on osteogenic differentiation of BMS cells was determined by measuring alkaline phosphatase (ALPase) activity, calcium content, and mRNA expression levels of osteogenic markers. There was a strong correlation between the fiber and cell distributions for the random (p = 0.16) and aligned (p = 0.81) fibers. Percent deviation from ideal randomness (PDIR) values indicated that cells seeded on the random fibers (PDIR = 6.5%) were likely to be distributed randomly in all directions while cells seeded on the aligned fibers (PDIR = 86%) were highly likely to be aligned with the direction of fibers. BMS cell seeded on random and aligned fibers had similar cell count and ALPase activity with incubation time, but the calcium content on aligned fibers was significantly higher after 21 days compared to that of random fibers (p = 0.003). Osteopontin (OP) and osteocalcin (OC) expression levels of BMS cells on fibers increased with incubation time. However, there was no difference between the expression levels of OP and OC on aligned vs. random fibers. The results indicate that BMS cells aligned in the direction of PLLA fibers to form long cell extensions, and fiber orientation affected the extent of mineralization, but it had no effect on cell proliferation or mRNA expression of osteogenic markers.

Osteogenic Differentiation of Marrow Stromal Cells on Random and Aligned Electrospun Poly(l-lactide) Nanofibers

Material Properties and Osteogenic Differentiation of Marrow Stromal Cells on Fiber-Reinforced Laminated Hydrogel Nanocomposites

Migration of marrow stromal cells in response to sustained release of stromal-derived factor-1α from poly(lactide ethylene oxide fumarate) hydrogels

Purpose
Biodegradable core-shell polymeric nanoparticles (NPs), with a hydrophobic core and hydrophilic shell, are developed for surfactant-free encapsulation and delivery of Paclitaxel to tumor cells.

Junyu Ma

Papers

Effect of grafting RGD and BMP-2 protein-derived peptides to a hydrogel substrate on osteogenic differentiation of marrow stromal cells.

Osteogenic Differentiation of Marrow Stromal Cells on Random and Aligned Electrospun Poly(l-lactide) Nanofibers

Material Properties and Osteogenic Differentiation of Marrow Stromal Cells on Fiber-Reinforced Laminated Hydrogel Nanocomposites

Migration of marrow stromal cells in response to sustained release of stromal-derived factor-1α from poly(lactide ethylene oxide fumarate) hydrogels

Cytotoxicity of Paclitaxel in Biodegradable Self-Assembled Core-Shell Poly(Lactide-Co-Glycolide Ethylene Oxide Fumarate) Nanoparticles