Characterization of an injectable, degradable polymer for mechanical stabilization of mandibular fractures.

This study investigated the use of injectable poly(propylene fumarate) (PPF) formulations for mandibular fracture stabilization applications. A full factorial design with main effects analysis was employed to evaluate the effects of the PPF:N-vinyl pyrrolidone (NVP, crosslinking agent) ratio and dimethyl toluidine (DMT, accelerator) concentration on key physicochemical properties including setting time, maximum temperature, mechanical properties, sol fraction, and swelling ratio. Additionally, the effects of formulation crosslinking time on the mechanical and swelling properties were investigated.

Characterization of porous polymethylmethacrylate space maintainers for craniofacial reconstruction.

Porous polymethylmethacrylate (PMMA) has been used as an alloplastic bone substitute in the craniofacial complex, showing integration with the surrounding soft and hard tissue. This study investigated the physicochemical properties of curing and cured mixtures of a PMMA-based bone cement and a carboxymethylcellulose (CMC) gel porogen. Four formulations yielding porous PMMA of varied porosity were examined; specifically, two groups containing 30% (w/w) CMC gel in the mixture using a 7% (w/v) or 9% (w/v) stock CMC gel (30-7 and 30-9, respectively) and two groups containing 40% (w/w) CMC gel (40-7 and 40-9).

Harnessing cell–biomaterial interactions for osteochondral tissue regeneration.

Articular cartilage that is damaged or diseased often requires surgical intervention to repair the tissue; therefore, tissue engineering strategies have been developed to aid in cartilage regeneration. Tissue engineering approaches often require the integration of cells, biomaterials, and growth factors to direct and support tissue formation. A variety of cell types have been isolated from adipose, bone marrow, muscle, and skin tissue to promote cartilage regeneration.

Porous EH and EH-PEG scaffolds as gene delivery vehicles to skeletal muscle.

Purpose: Synthetic biomaterials are widely used in an attempt to control the cellular behavior of regenerative tissues. This can be done by altering the chemical and physical properties of the polymeric scaffold to guide tissue repair. This paper addresses the use of a polymeric scaffold (EH network) made from the cyclic acetal monomer, 5-ethyl-5-(hydroxymethyl)-β,β-dimethyl-1,3-dioxane-2-ethanol diacrylate (EHD), as a release device for a therapeutic plasmid encoding for an insulin-like growth factor-1 green fluorescent protein fusion protein (IGF-1 GFP).

Shaping the micromechanical behavior of multi-phase composites for bone tissue engineering.

Mechanical stiffness is a fundamental parameter in the rational design of composites for bone tissue engineering in that it affects both the mechanical stability and the osteo-regeneration process at the fracture site. A mathematical model is presented for predicting the effective Young's modulus (E) and shear modulus (G) of a multi-phase biocomposite as a function of the geometry, material properties and volume concentration of each individual phase. It is demonstrated that the shape of the reinforcing particles may dramatically affect the mechanical stiffness: E and G can be maximized by employing particles with large geometrical anisotropy, such as thin platelet-like or long fibrillar-like particles.

Addition of hyaluronic acid to alginate embedded chondrocytes interferes with insulin-like growth factor-1 signaling in vitro and in vivo.

The development of an engineered tissue requires a clear understanding of the interactions between the individual components. In this study, we investigated how the addition of hyaluronic acid (HA) to a cartilage tissue engineered scaffold alters chondrocytic expression, and specifically the expression of insulin-like growth factor-1 (IGF-1) signaling molecules. Bovine chondrocytes were embedded (7 million cells/mL) in 2.

Osteogenic differentiation of bone marrow stromal cells induced by coculture with chondrocytes encapsulated in three-dimensional matrices.

Endochondral ossification implicates chondrocyte signaling as an important factor in directing the osteogenic differentiation of mesenchymal stem cells in vivo. In this study, the osteoinductive capabilities of articular chondrocytes suspended in alginate hydrogels were analyzed via coculture with bone marrow stromal cells (BMSCs). In particular, the effect of chondrocyte coculture time on the mechanism underlying this osteogenic induction was examined.

Effects of exogenous IGF-1 delivery on the early expression of IGF-1 signaling molecules by alginate embedded chondrocytes.

Cartilage tissue engineering remains a significant challenge for both researchers and clinicians. Many strategic approaches, such as the delivery of growth factors to an in vitro cultured cartilage construct, continue to receive significant attention. However, the effects of delivering exogenous signaling molecules on endogenous signaling pathways within an engineered tissue are not well understood.

Chondrocyte signaling and artificial matrices for articular cartilage engineering.

Chondrocytes depend on their environment to aid in their expression of appropriate proteins. It has been found that the interaction of integrin receptors with chondrocytes effects the production of extracellular molecules such as type II collagen and aggrecan. Additionally, the presence of growth factors such as IGF-1, TGF-beta1 and BMP-7 induce various signaling pathways that also aid in transducing phenotypic expressions by chondrocytes.

Effect of construct properties on encapsulated chondrocyte expression of insulin-like growth factor-1.

Hydrogels are a promising type of biomaterial for articular cartilage constructs since they have been shown to enable encapsulated chondrocytes to express their predominant phenotypic marker, type II collagen. Endogenously expressed signaling molecules, such as insulin-like growth factor-1 (IGF-1), are also known to facilitate the retention of this chondrocytic phenotype. Recent investigations have attempted to enhance the ability of encapsulated chondrocytes to regenerate cartilage through delivery of exogenous signaling molecules.