Multiscale osteointegration as a new paradigm for the design of calcium phosphate scaffolds for bone regeneration.

The role of macropore size (>100 microm) and geometry in synthetic scaffolds for bone regeneration has been studied extensively, but successful translation to the clinic has been slow. Significantly less attention has been given to porosity at the microscale (0.5-10 microm).

Accelerated wound closure of pressure ulcers in aged mice by chitosan scaffolds with and without bFGF.

Pressure ulcers are a significant healthcare concern, especially for elderly populations. Our work served to ameliorate the chronicity of these ulcers by addressing ischemia-reperfusion injury mediated by neutrophils and the concomitant loss of vasculature in these wounds. To this end, chitosan scaffolds loaded with basic fibroblast growth factor (bFGF) contained in gelatin microparticles were developed and tested for clinical relevance in an aged mouse model.

The effect of chitosan on the migration of neutrophil-like HL60 cells, mediated by IL-8.

Research interest in chitosan stems in part from the demonstrated wound healing properties. The benefits of chitosan as a therapeutic agent appear to be paradoxical because chitosan also elicits neutrophil infiltration indicative of an inflammatory response. While the affinity between chitosan and neutrophils has been well documented, the underlying mechanism is unclear.

Robotic deposition of model hydroxyapatite scaffolds with multiple architectures and multiscale porosity for bone tissue engineering.

Model hydroxyapatite (HA) scaffolds with porosities spanning multiple length scales were fabricated by robocasting, a solid freeform fabrication technique based on the robotic deposition of colloidal pastes. Scaffolds of various architectures including periodic, radial, and superlattice structures were constructed. Macropores (100-600 microm) were designed by controlling the arrangement and spacing between rods of HA.

The addition of biphasic calcium phosphate to porous chitosan scaffolds enhances bone tissue development in vitro.

Uniform distribution of cells and their extracellular matrix is essential for the in vivo success of bone tissue engineering constructs produced in vitro. In this study, the effects of biphasic calcium phosphate (BCP) granules embedded into chitosan scaffolds on the distribution, morphology, and phenotypic expression of osteoblastic cells were investigated. Mesenchymal stem cells (MSCs) and preosteoblasts were cultured on chitosan scaffolds with and without BCP under osteoblastic differentiation/maturation conditions for periods up to 4 weeks.

The mechanical properties and osteoconductivity of hydroxyapatite bone scaffolds with multi-scale porosity.

The relative osteoconductivity and the change in the mechanical properties of hydroxyapatite (HA) scaffolds with multi-scale porosity were compared to scaffolds with a single pore size. Non-microporous (NMP) scaffolds contained only macroporosity (250-350 microm) and microporous (MP) scaffolds contained both macroporosity and microporosity (2-8 microm). Recombinant human bone morphogenetic protein-2 (rhBMP-2) was incorporated into all scaffolds via gelatin microspheres prior to implantation into the latissimus dorsi muscle of Yorkshire pigs.

Effects of degradation and porosity on the load bearing properties of model hydroxyapatite bone scaffolds.

Degradation of three types of model hydroxyapatite (HA) scaffolds was studied after in vitro degradation in a sodium acetate buffer (pH 4). Degradation was evaluated using compression testing, scanning electron microscopy (SEM), inductively coupled plasma (ICP) analysis, and weight measurements. Scaffolds were fabricated with a solid freeform fabrication (SFF) technique based on the robotic deposition of colloidal pastes.

Bone response to 3D periodic hydroxyapatite scaffolds with and without tailored microporosity to deliver bone morphogenetic protein 2.

Three types of model hydroxyapatite (HA) scaffolds were implanted in the metacarpal and metatarsal bones of goats. Scaffolds, consisting of a latticed pattern of rods, were fabricated with a solid freeform fabrication (SFF) technique. All scaffolds contained macropores; some were also fabricated with micropores (5.

Effect of transforming growth factor-beta1 on bone regeneration in critical-sized bone defects after irradiation of host tissues.

Objective: To determine whether sustained release of transforming growth factor (TGF)-beta1 from a gelatin hydrogel would enhance bone regeneration in critical-sized long-bone defects and overcome inhibitory effects of preoperative irradiation.

Animals: 24 adult New Zealand White rabbits.

Procedure: Rabbits were allocated to 2 groups.