Elijah Nyairo

Aligned PLGA/HA nanofibrous nanocomposite scaffolds for bone tissue engineering.

Aligned nanofibrous scaffolds based on poly(d,l-lactide-co-glycolide) (PLGA) and nano-hydroxyapatite (nano-HA) were synthesized by electrospinning for bone tissue engineering. Morphological characterization using scanning electron microscopy showed that the addition of different amounts of nano-HA (1, 5, 10 and 20wt.%) increased the average fiber diameter from 300nm (neat PLGA) to 700nm (20% nano-HA). At higher concentrations (>or=10%), agglomeration of HA was observed and this had a marked effect at 20% concentration whereby the presence of nano-HA resulted in fiber breaking. Thermal characterization showed that the fast processing of electrospinning locked in the amorphous character of PLGA; this resulted in a decrease in the glass transition temperature of the scaffolds. Furthermore, an increase in the glass transition temperature was observed with increasing nano-HA concentration. The dynamic mechanical behavior of the scaffolds reflected the morphological observation, whereby nano-HA acted as reinforcements at lower concentrations (1% and 5%) but acted as defects at higher concentrations (10% and 20%). The storage modulus value of the scaffolds increased from 441MPa for neat PLGA to 724MPa for 5% nano-HA; however, further increasing the concentration leads to a decrease in storage modulus, to 371MPa for 20% nano-HA. Degradation characteristics showed that hydrophilic nano-HA influenced phosphate-buffered saline uptake and mass loss. The mechanical behavior showed a sinusoidal trend with a slight decrease in modulus by week 1 due to the plasticizing effect of the medium followed by an increase due to shrinkage, and a subsequent drop by week 6 due to degradation.

Aligned bioactive multi-component nanofibrous nanocomposite scaffolds for bone tissue engineering.

The ability to mimic the chemical, physical and mechanical properties of the natural extra-cellular matrix is a key requirement for tissue engineering scaffolds to be successful. In this study, we successfully fabricated aligned nanofibrous multi-component scaffolds for bone tissue engineering using electrospinning. The chemical features were mimicked by using the natural components of bone: collagen and nano-hydroxyapatite along with poly[(D,L-lactide)-co-glycolide] as the major component. Anisotropic features were mimicked by aligning the nanofibers using a rotating mandrel collector. We evaluated the effect of incorporation of nano-HA particles to the system. The morphology and mechanical properties revealed that,at low concentrations, nano-HA acted as a reinforcement. However, at higher nano-HA loadings, it was difficult to disrupt aggregations and, hence, a detrimental effect was observed on the overall scaffold properties. Thermal analysis showed that there were slight interactions between the individual components even though the polymers existed as a two-phase system. Preliminary in vitro cell-culture studies revealed that the scaffold supported cell adhesion and spreading. The cells assumed a highly aligned morphology along the direction of fiber orientation. Protein adsorption experiments revealed that the synergistic effect of increased surface area and the presence of nano-HA in the polymer matrix enhanced total protein adsorption. Crosslinking with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride resulted in improved mechanical properties of the scaffolds and improved degradation stability, under physiological conditions.

Interleukin-10 Conjugation to Carboxylated PVP-Coated Silver Nanoparticles for Improved Stability and Therapeutic Efficacy

Interleukin-10 (IL-10) is a key anti-inflammatory and immunosuppressive cytokine and therefore represents a potential therapeutic agent especially in inflammatory diseases. However, despite its proven therapeutic efficacy, its short half-life and proteolytic degradation in vivo combined with its low storage stability have limited its therapeutic use. Strategies have been developed to overcome most of these shortcomings, including in particular bioconjugation with stabilizing agents such as polyethylene glycol (PEG) and poly (vinylpyrolidone) (PVP), but so far these have had limited success. In this paper, we present an alternative method consisting of bioconjugating IL-10 to PVP-coated silver nanoparticles (Ag-PVPs) in order to achieve its storage stability by preventing denaturation and to improve its anti-inflammatory efficacy. Silver nanoparticles capped with a carboxylated PVP were produced and further covalently conjugated with IL-10 protein by carbodiimide crosslinker chemistry. The IL-10 conjugated Ag-PVPs exhibited increased stability and anti-inflammatory effectiveness in vitro. This study therefore provides a novel approach to bioconjugating PVP-coated silver nanoparticles with therapeutic proteins, which could be useful in drug delivery and anti-inflammatory therapies.

Abstract 4107: Efficient delivery of dietary compound modulates mcp-1 in murine prostate cancer cells

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Monocyte chemo-attractant protein (MCP-1) is a chemokine, which recruits monocytes, neutrophils, and lymphocytes in response to trauma and proinflammatory cytokines such as TNF-α. MCP-1 generally is not expressed in healthy individuals, but in response to various stressful stimuli it gets up-regulated, which in turn contributes to increased inflammation. MCP-1 has been implicated in mediating apoptosis by producing a proapoptotic protein designated MCP-induced protein (MCPIP). Resveratrol (RES), a polyphenolic compound found in the skin of red fruits, exhibits anti-inflammatory, anti-oxidative, anti-cancer, and anti-proliferative characteristics. In this study, we hypothesized that the functionalization of RES with detonated nano-diamond (DND, hereafter called fDND) will enhance the effective delivery of RES to tumor cell and impact the modulation of molecular mechanisms in murine prostate cancer (PCa) cells. This hypothesis was tested on mouse PCa cell lines, derived from transgenic adenocarcinoma of mouse prostate (TRAMP), in C57/B6 mice. Interestingly, TRAMP-C1 and TRAMP-C2 form tumor while TRAMP-C3 fails to develop tumor. TRAMP cells were treated with different concentrations of fDND at different time points and analyzed for underlying cellular and molecular mechanisms such as cell viability/proliferation, mitochondrial membrane potential, cytokines and growth factors production. The initial results indicate that the fDND significantly induce molecular signatures in TRAMP-C3 cells in comparison with TRAMPC1 and C2. Interestingly, the level of MCP-1 was significant elevated in TRAMP C1 and C2 cells. Thus, suggesting a major role of MCP-1 in the regulation of cancer progression and clearance. This data also suggest that the functionality of dietary compounds can be enhanced by conjugating or functionalizing them with DND, which can be used as a therapeutic carrier. Citation Format: Manoj K. Mishra, James A. Stokes, Amanee Salaam, Elijah Nyairo, Udai Singh, Derrick Dean. Efficient delivery of dietary compound modulates mcp-1 in murine prostate cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4107. doi:10.1158/1538-7445.AM2014-4107