Bio Focus: Hard talk to stem cells for new bone growth
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o Focus Hard talk to stem cells for new bone growth
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ynthetic materials have widely enabled medical repairs and replacements for damaged bones, such as in the use of fracture-supporting metal rods and artificial hips. These biomaterials are rapidly improving, but suffer from several limitations: they call for invasive surgery, are associated with painful recoveries, and lack the capacity to organically selfheal. With new developments in stem cell biology, tissue engineers dream of overcoming these traditional biomaterial limitations by ultimately regrowing injured bones, good as new. The opportunity arises from the natural ability of stem cells to differentiate (i.e., transform themselves) into new bone-growing cells called osteoblasts, but the challenge lies in successfully coaxing this transformation to occur when, where, and in the way that one desires. A.H. Ambre, D.R. Katti, and K.S. Katti of North Dakota State University have recently approached this challenge by exploring the use of clay-based composites as potential scaffold materials for bone regeneration. An ideal scaffold material would support the growth of stem cells, induce their differentiation to osteoblasts, and template osteoblast-directed mineralization into the desired bone-like biomaterial. In practice, achieving a scaffold that performs these functions is highly challenging, as stem cells respond differently to differing material surface structures
they removed from the growth wafer and direct-bonded to both planar and curved amorphous silica substrates. Next, using a Sr lattice clock laser with record frequency stability and an Yb fiber frequency comb, they measured the noise properties of an optical cavity formed from these mirrors. In close agreement with theory, they found a reduction of at least a factor of 10 in the coating noise at 1 Hz compared to state-of-the-art SiO2/ Ta2O5-based mirrors.
and chemistries, and design rules are elusive at present. In an article published in the September issue of the Journal of Biomedical Materials Research A (DOI: 10.1002/ jbm.a.34561; p. 2644), the research team provides evidence that films comprising combinations of sugar derivatives (chitosan and polygalacturonic acid), alumino-silicate clay nanoparticles, and hydroxyapatite (HAP) may induce the differentiation of mesenchymal stem cells into osteoblasts on the film surfaces. The study shows that the method selected for composite synthesis affects the celldirecting properties of the resulting films, and determines whether the clay material makes a difference. If clay and HAP particles are added to a premixed solution of the two biopolymers, the resulting composite seems to support increased stem cell growth and differentiation relative to control materials with no clay-based mineral. However, if the mineral fraction is combined with chitosan first, followed by polygalacturonic acid addition, the claycontaining composite shows little difference in influencing cell behavior relative to clay-free counterpart materials. These results are consistent w
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