ECENT CLINICAL TRIALS SUGgest that bone marrowderived cell preparations, including mononuclear cells 1-5 and mesenchymal stem cells (MSCs), [6][7][8] can ameliorate left ventricular (LV) remodeling in patients with acute 1,3,8 and chronic 2,4,6,9 ischemic cardiomyopathy (ICM). An important issue in this new field is whether a certain cellular constituent Author Affiliations are listed at the end of this article.

To demonstrate the safety of transendocardial stem cell injection (TESI) with autologous MSCs and BMCs in patients with ICM.• To assess prespecified outcomes of efficacy.

The highly debilitating nature of spinal cord injuries has provided much inspiration for the design of novel biomaterials that can stimulate cellular regeneration and functional recovery. Many experts agree that the greatest hope for treatment of spinal cord injuries will involve a combinatorial approach that integrates biomaterial scaffolds, cell transplantation, and molecule delivery. This manuscript presents a comprehensive review of biomaterial-scaffold design strategies currently being applied to the development of nerve guidance channels and hydrogels that more effectively stimulate spinal cord tissue regeneration. To enhance the regenerative capacity of these two scaffold types, researchers are focusing on optimizing the mechanical properties, cell-adhesivity, biodegradability, electrical activity, and topography of synthetic and natural materials, and are developing mechanisms to use these scaffolds to deliver cells and biomolecules. Developing scaffolds that address several of these key design parameters will lead to more successful therapies for the regeneration of spinal cord tissue.

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Spider silk fibers have remarkable mechanical properties that suggest the component proteins could be useful biopolymers for fabricating biomaterial scaffolds for tissue formation. Two bioengineered protein variants from the consensus sequence of the major component of dragline silk from Nephila clavipes were cloned and expressed to include RGD cell-binding domains. The engineered silks were characterized by CD and FTIR and showed structural transitions from random coil to insoluble beta-sheet upon treatment with methanol. The recombinant proteins were processed into films and fibers and successfully used as biomaterial matrixes to culture human bone marrow stromal cells induced to differentiate into bone-like tissue upon addition of osteogenic stimulants. The recombinant spider silk and the recombinant spider silk with RGD encoded into the protein both supported enhanced the differentiation of human bone marrow derived mesenchymal stem cells (hMSCs) to osteogenic outcomes when compared to tissue culture plastic. The recombinant spider silk protein without the RGD displayed enhanced bone related outcomes, measured by calcium deposition, when compared to the same protein with RGD. Based on comparisons to our prior studies with silkworm silks and RGD modifications, the current results illustrate the potential to bioengineer spider silk proteins into new biomaterial matrixes, while also highlighting the importance of subtle differences in silk sources and modes of presentation of RGD to cells in terms of tissue-specific outcomes.

Silica skeletal architectures in diatoms are characterized by remarkable morphological and nanostructural details. Silk proteins from spiders and silkworms form strong and intricate self-assembling fibrous biomaterials in nature. We combined the features of silk with biosilica through the design, synthesis, and characterization of a novel family of chimeric proteins for subsequent use in model materials forming reactions. The domains from the major ampullate spidroin 1 (MaSp1) protein of Nephila clavipes spider dragline silk provide control over structural and morphological details because it can be self-assembled through diverse processing methods including film casting and fiber electrospinning. Biosilica nanostructures in diatoms are formed in aqueous ambient conditions at neutral pH and low temperatures. The R5 peptide derived from the silaffin protein of Cylindrotheca fusiformis induces and regulates silica precipitation in the chimeric protein designs under similar ambient conditions. Whereas mineralization reactions performed in the presence of R5 peptide alone form silica particles with a size distribution of 0.5-10 m in diameter, reactions performed in the presence of the new fusion proteins generate nanocomposite materials containing silica particles with a narrower size distribution of 0.5-2 m in diameter. Furthermore, we demonstrate that composite morphology and structure could be regulated by controlling processing conditions to produce films and fibers. These results suggest that the chimeric protein provides new options for processing and control over silica particle sizes, important benefits for biomedical and specialty materials, particularly in light of the all aqueous processing and the nanocomposite features of these new materials.biomaterials ͉ nanostructures ͉ silaffin ͉ biomineralization ͉ ceramics C omplex mineralized composite systems in nature provide rich ground for insight into mechanisms of biomineralization and novel materials designs (1-4). Some of the more common sources of inspiration include seashells, insect exoskeletons, extracellular matrices involved in bone and other hard tissues, and biosilica skeletons. The formation of natural inorganic-organic composites is a multistep process, including the assembly of the extracellular matrix, the selective transportation of inorganic ions to discrete organized compartments with subsequent mineral nucleation, and growth delineated by preorganized cellular compartments. Silica skeletons found in nature are based on nanoscale composites wherein the organic components, usually proteins, are functional parts of the skeletal structures while also serving as silica-forming components (5, 6). As a result, materials' toughness is improved, strength is retained, and fine morphological control is achieved, all hallmark attributes of biological composites.Silica is widespread in biological systems and serves different functions, including support and protection in single-celled organisms, such as diatoms through to higher plants and animals (7,8...

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