Pluripotent Stem Cells: chapter 26, Stem Cells in Tissue Engineering

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Alginate/cartilage extracellular matrix-based injectable interpenetrating polymer network hydrogel for cartilage tissue engineering

The authors are also grateful to Dr Zabihollah Hasanzadeh for providing cartilage tissue, Ghaffari Chemical Industries for the technical support, and Mojtaba Khozaee for isolating chondrocyte cells from the human articular cartilage specimens. The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Sharif University of Technology (grant number G950103).In the present study, alginate/cartilage extracellular matrix (ECM)-based injectable hydrogel was developed incorporated with silk fibroin nanofibers (SFN) for cartilage tissue engineering. The in situ forming hydrogels were composed of different ionic crosslinked alginate concentrations with 1% w/v enzymatically crosslinked phenolized cartilage ECM, resulting in an interpenetrating polymer network (IPN). The response surface methodology (RSM) approach was applied to optimize IPN hydrogel's mechanical properties by varying alginate and SFN concentrations. The results demonstrated that upon increasing the alginate concentration, the compression modulus improved. The SFN concentration was optimized to reach a desired mechanical stiffness. Accordingly, the concentrations of alginate and SFN to have an optimum compression modulus in the hydrogel were found to be 1.685 and 1.724% w/v, respectively. The gelation time was found to be about 10 s for all the samples. Scanning electron microscope (SEM) images showed homogeneous dispersion of the SFN in the hydrogel, mimicking the natural cartilage environment. Furthermore, water uptake capacity, degradation rate, cell cytotoxicity, and glycosaminoglycan and collagen II secretions were determined for the optimum hydrogel to support its potential as an injectable scaffold for articular cartilage defects.Peer reviewe

Embryonic Stem Cells Maintain an Undifferentiated State on Dendrimer-Immobilized Surface with d-Glucose Display

In serial passaging cultures of mouse embryonic stem (ES) cells, we employed a dendrimer-immobilized substrate that displayed d-glucose as a terminal ligand. The d-glucose-displaying dendrimer (GLU/D) surface caused the ES cells to form loosely attached spherical colonies, while those on a gelatin-coated surface formed flatter colonies that were firmly attached to the surface. Despite the morphological similarities between the colonies on the GLU/D surface and aggregates on a conventional bacteriological dish, immunostaining and RT-PCR analyses revealed the maintenance of cells within the spherical colonies on the GLU/D surface in an undifferentiated state with very low expressions of primitive endoderm markers. On the bacteriological dish, however, the cells within the aggregates showed a different cellular state with partial differentiation into the primitive endoderm lineage, and the expression level increased gradually along with the number of passages. These results indicate that the GLU/D surface can be a potential tool for controlling the ES cell morphology and then govern their self-renewal and fate

Effect of Physico-Chemical Properties of Nanoparticles on Their Intracellular Uptake

Cellular internalization of inorganic, lipidic and polymeric nanoparticles is of great significance in the quest to develop effective formulations for the treatment of high morbidity rate diseases. Understanding nanoparticle–cell interactions plays a key role in therapeutic interventions, and it continues to be a topic of great interest to both chemists and biologists. The mechanistic evaluation of cellular uptake is quite complex and is continuously being aided by the design of nanocarriers with desired physico-chemical properties. The progress in biomedicine, including enhancing the rate of uptake by the cells, is being made through the development of structure–property relationships in nanoparticles. We summarize here investigations related to transport pathways through active and passive mechanisms, and the role played by physico-chemical properties of nanoparticles, including size, geometry or shape, core-corona structure, surface chemistry, ligand binding and mechanical effects, in influencing intracellular delivery. It is becoming clear that designing nanoparticles with specific surface composition, and engineered physical and mechanical characteristics, can facilitate their internalization more efficiently into the targeted cells, as well as enhance the rate of cellular uptake

Chitosan-gelatin sheets as scaffolds for muscle tissue engineering

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