Intranasal delivery of a bivalent norovirus vaccine formulated in an in situ gelling dry powder.

The global health community is beginning to understand the burden of norovirus-associated disease, which has a significant impact in both developed and developing countries. Norovirus virus like particle (VLP)-based vaccines are currently under development and have been shown to elicit systemic and mucosal immune responses when delivered intranasally. In the present study, we describe the use of a dry powder formulation (GelVac™) with an in situ gelling polysaccharide (GelSite™) extracted from Aloe vera for nasal delivery of a bivalent vaccine formulation containing both GI and GII.4 norovirus VLPs. Dose-ranging studies were performed to identify the optimal antigen dosages based on systemic and mucosal immune responses in guinea pigs and determine any antigenic interference. A dose-dependent increase in systemic and mucosal immunogenicity against each of the VLPs were observed as well as a boosting effect for each VLP after the second dosing. A total antigen dose of ≥50 µg of each GI and GII.4 VLPs was determined to be the maximally immunogenic dose in guinea pigs. The immunogenicity results of this bivalent formulation, taken together with previous work on monovalent GelVac™ norovirus vaccine formulation, provides a basis for future development of this norovirus VLP vaccine.

Preclinical dose-ranging studies of a novel dry powder norovirus vaccine formulation.

Norovirus is the primary cause of viral gastroenteritis in humans with multiple genotypes currently circulating worldwide. The development of a successful norovirus vaccine is contingent on its ability to induce both systemic and mucosal antibody responses against a wide range of norovirus genotypes. Norovirus virus-like particles (VLPs) are known to elicit systemic and mucosal immune responses when delivered intranasally. Incorporation of these VLPs into an intranasal powder vaccine offers the advantage of simplicity and induction of neutralizing systemic and mucosal antibodies. Nasal immunization, which provides the advantage of ease of administration and a mucosal delivery mechanism, faces the real issue of limited nasal residence time due to mucociliary clearance. Herein, we describe a novel dry powder (GelVac™) formulation of GI or GII.4 norovirus VLPs, two dominant circulating genotypes, to identify the optimal antigen dosages based on systemic and mucosal immune responses in guinea pigs. Systemic and mucosal immunogenicity of each of the VLPs was observed in a dose-dependent manner. In addition, a boosting effect was observed after the second dosing of each VLP antigen. With the GelVac™ formulation, a total antigen dose of ≥ 15 µg was determined to be the maximally immunogenic dose for both GI and GII.4 norovirus VLPs based on evaluation for 56 days. Taken together, these results indicate that norovirus VLPs could be used as potential vaccine candidates without using an immunostimulatory adjuvant and provide a basis for the development of a GelVac™ bivalent GI/GII.4 norovirus VLP vaccine.

Biocompatibility evaluation of porous ceria foams for orthopedic tissue engineering.

Ceria ceramics have the unique ability to protect cells from free radical-induced damage, making them materials of interest for biomedical applications. To expand upon the understanding of the potential of ceria as a biomaterial, porous ceria, fabricated via direct foaming, was investigated to assess its biocompatibility and its ability to scavenge free radicals. A mouse osteoblast (7F2) cell line was cultured with the ceria foams to determine the extent of the foams' toxicity. Toxicity assessments indicate that mouse osteoblasts cultured directly on the ceria scaffold for 72 h did not show a significant (p > 0.05) increase in toxicity, but rather show comparable toxicity to cells cultured on porous 45S5 Bioglass. The in vitro inflammatory response elicited from porous ceria foams was measured as a function of tumor necrosis factor alpha (TNF-α) secreted from a human monocytic leukemia cell line. Results indicate that the ceria foams do not cause a significant inflammatory response, eliciting a response of 27.1 ± 7.1 pg mL(-1) of TNF-α compared to 36.3 ± 5.8 pg mL(-1) from cells on Bioglass, and 20.1 ± 2.9 pg mL(-1) from untreated cells. Finally, we report cellular toxicity in response to free radicals from tert-butyl hydroperoxide with and without foamed ceria. Our preliminary results show that the foamed ceria is able to decrease the toxic effect of induced oxidative stress. Collectively, this study demonstrates that foamed ceria scaffolds do not activate an inflammatory response, and show potential free radical scavenging ability, thus they have promise as an orthopedic biomaterial.

Biocompatible evaluation of barium titanate foamed ceramic structures for orthopedic applications.

The potential of barium titanate (BT) to be electrically active makes it a material of interest in regenerative medicine. To enhance the understanding of this material for orthopedic applications, the in vitro biocompatibility of porous BT fabricated using a direct foaming technique was investigated. Characterization of the resultant foams yielded an overall porosity between 50 and 70% with average pore size in excess of 30 µm in diameter. A mouse osteoblast (7F2) cell line was cultured with the BT to determine the extent of the foams' toxicity using a LDH assay. After 72 h, BT foams showed a comparable cytotoxicity of 6.4 ± 0.8% to the 8.4 ± 1.5% of porous 45S5 Bioglass®. The in vitro inflammatory response elicited from porous BT was measured as a function of tumor necrosis factor alpha (TNF-α) secreted from a human monocytic leukemia cell line (THP-1). Results indicate that the BT foams do not cause a significant inflammatory response, eliciting a 9.4 ± 1.3 pg of TNF-α per mL of media compared with 20.2 ± 2.3 pg/mL from untreated cells. These results indicate that porous BT does not exhibit short term cytotoxicity and has potential for orthopedic tissue engineering applications.

Advanced nanocomposites for bone regeneration.

The field of orthopedic tissue engineering is quickly expanding with the development of novel materials and strategies designed for rapid bone regeneration. While autologous bone grafts continue to be the standard of care, drawbacks include donor-site morbidity and short tissue supplies. Herein we report a novel nanocomposite sponge composed of poly(1,8-octanediol-co-citrate) (POC) and the bioactive ceramic ß-tricalcium phosphate (TCP). We show that these nanocomposite sponges can be used as a depot for bone-producing (a.k.a. osteogenic) growth factors. In vitro bioactivity is demonstrated by significant upregulation of osteogenic genes, osteopontin (∼3 fold increase), osteocalcin (∼22 fold increase), alkaline phosphatase (∼10 fold increase), and transcription factor, RUNX2 (∼5 fold increase) over basal expression levels in mesenchymal stem cells. In vivo osteogenicity and biocompatibility is demonstrated in a standard subcutaneous implant model in rat. Results show that the nanocomposite sponge supports complete cell infiltration, minimal adverse foreign body response, positive cellular proliferation, and cellular expression of osteogenic markers in subcutaneous tissue. The results shown herein are encouraging and support the use of this sponge for future bone tissue engineering efforts.

A study of a biodegradable Mg-3Sc-3Y alloy and the effect of self-passivation on the in vitro degradation.

Magnesium and its alloys have been investigated for their potential application as biodegradable implant materials. Although properties of magnesium such as biocompatibility and susceptibility to dissolution are desirable for biodegradable implant applications, its high degradation rate and low strength pose a significant challenge. A potential way to reduce the initial degradation rate is to form a self-passivating protective layer on the surface of the alloy. Oxides with a low enthalpy of formation result in a strong thermodynamic driving force to produce oxide surfaces that are more stable than the native oxide (MgO), and possibly reduce the initial degradation rate in these alloys. In the present study a ternary Mg-3wt.% Sc-3wt.% Y alloy was investigated and its oxidation behavior studied. The effect of surface passivation on the in vitro degradation rate was studied and the degradation products identified. The results show that the oxide provided an initial degradation barrier and 24h oxidation resulted in a negligible degradation rate for up to 23 days. Furthermore, the degradation products of the alloy showed no significant toxicity to osteoblastic cells, and cell proliferation studies confirmed cell attachment and proliferation on the surface of the oxidized alloy.