A canine in vitro model for evaluation of marrow-derived mesenchymal stromal cell-based bone scaffolds.

Tissue engineered bone grafts based on bone marrow mesenchymal stromal cells (MSCs) are being actively developed for craniomaxillofacial (CMF) applications. As for all tissue engineered implants, the bone-regenerating capacity of these MSC-based grafts must first be evaluated in animal models prior to human trials. Canine models have traditionally resulted in improved clinical translation of CMF grafts relative to other animal models.

Characterization of sequential collagen-poly(ethylene glycol) diacrylate interpenetrating networks and initial assessment of their potential for vascular tissue engineering.

Collagen hydrogels have been widely investigated as scaffolds for vascular tissue engineering due in part to the capacity of collagen to promote robust cell adhesion and elongation. However, collagen hydrogels display relatively low stiffness and strength, are thrombogenic, and are highly susceptible to cell-mediated contraction. In the current work, we develop and characterize a sequentially-formed interpenetrating network (IPN) that retains the benefits of collagen, but which displays enhanced mechanical stiffness and strength, improved thromboresistance, high physical stability and resistance to contraction.

Influence of pressurized cyclic stretch and endothelial cell presence on multipotent stem cell osteogenic commitment.

Applied mechanical stretch and blood vessel invasion are key stimuli to which progenitor cells are exposed in post-natal endochondral bone formation. Understanding the combined effects of cyclic stretch and endothelial cell (EC) presence on multipotent stem cell (MSC) osteogenesis therefore has the potential to lead to improved MSC-based bone regeneration strategies. Toward this goal, 10T1/2 mouse MSCs were encapsulated in tubular poly(ethylene glycol) diacrylate [PEGDA] hydrogels with moduli within the "osteogenic" range in order to induce osteogenesis.

Osteogenic potential of poly(ethylene glycol)-poly(dimethylsiloxane) hybrid hydrogels.

Growth factors have been shown to be potent mediators of osteogenesis. However, their use in tissue-engineered scaffolds not only can be costly but also can induce undesired responses in surrounding tissues. Thus, the ability to specifically induce osteogenic differentiation in the absence of exogenous growth factors through manipulation of scaffold material properties would be desirable for bone regeneration.

Influence of glycosaminoglycan identity on vocal fold fibroblast behavior.

Poly(ethylene glycol) (PEG) hydrogels have recently begun to be studied for the treatment of scarred vocal fold lamina propria due, in part, to their tunable mechanical properties, resistance to fibroblast-mediated contraction, and ability to be polymerized in situ. However, pure PEG gels lack intrinsic biochemical signals to guide cell behavior and generally fail to mimic the frequency-dependent viscoelastic response critical to normal superficial lamina propria function. Recent results suggest that incorporation of viscoelastic bioactive substances, such as glycosaminoglycans (GAGs), into PEG networks may allow these gels to more closely approach the mechanical responses of normal vocal fold lamina propria while also stimulating desired vocal fold fibroblast behaviors.

Regulation of smooth muscle cell phenotype by glycosaminoglycan identity.

The retention of lipoproteins in the arterial intima is an initial event in early atherosclerosis and occurs, in part, through interactions between negatively charged glycosaminoglycans (GAGs) and the positively charged residues of apolipoproteins. Smooth muscle cells (SMCs) which infiltrate into the lipoprotein-enriched intima have been observed to transform into lipid-laden foam cells. This phenotypic switch is associated with SMC acquisition of a macrophage-like capacity to phagocytose lipoproteins and/or of an adipocyte-like capacity to synthesize fatty acids de novo.

Hydrogel-electrospun mesh composites for coronary artery bypass grafts.

The aim of the present study was to investigate the potential of hydrogel-electrospun mesh hybrid scaffolds as coronary artery bypass grafts. The circumferential mechanical properties of blood vessels modulate a broad range of phenomena, including vessel stress and mass transport, which, in turn, have a critical impact on cardiovascular function. Thus, coronary artery bypass grafts should mimic key features of the nonlinear stress-strain behavior characteristic of coronary arteries.

Approach for fabricating tissue engineered vascular grafts with stable endothelialization.

A major roadblock in the development of tissue engineered vascular grafts (TEVGs) is achieving construct endothelialization that is stable under physiological stresses. The aim of the current study was to validate an approach for generating a mechanically stable layer of endothelial cells (ECs) in the lumen of TEVGs. To accomplish this goal, a unique method was developed to fabricate a thin EC layer using poly(ethylene glycol) diacrylate (PEGDA) as an intercellular "cementing" agent.

Probing vocal fold fibroblast response to hyaluronan in 3D contexts.

A number of treatments are being investigated for vocal fold (VF) scar, including designer implants. The aim of the present study was to validate a 3D model system for probing the effects of various bioactive moieties on VF fibroblast (VFF) behavior toward rational implant design. We selected poly(ethylene glycol) diacrylate (PEGDA) hydrogels as our base-scaffold due to their broadly tunable material properties.