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Thermolabile nature of commercially available vaccines necessitates their storage, transportation, and dissemination under refrigerated condition. Maintenance of continuous cold chain at every step increases the final cost of vaccines. Any breach in the cold chain even for a short duration results in the need to discard the vaccines. As a result, there is a pressing need for the development of thermostable vaccines. In this proof-of-concept study, we showed that E. coli curli-green fluorescent fusion protein remains stable in freeze-dried yeast powder for more than 18 and 12 months when stored at 30 °C and 37 °C respectively. Stability of the heterologous protein remains unaffected during the process of heat-inactivation and lyophilization. The mass of lyophilized yeast powder remains almost unchanged during the entire period of storage and expressed protein remains intact even after two cycles of freeze and thaws. The protease-deficient strain appears ideal for the development of whole recombinant yeast-based vaccines. The cellular abundance of expressed antigen in dry powder after a year was comparable to freshly lyophilized cells. Scanning electron microscopy showed the intact nature of cells in powdered form even after a year of storage at 30 °C. Observation made in this study showed that freeze-dry yeast powder can play a vital role in the development of thermostable vaccines. Key Points • Yeast-based vaccines can overcome problem of cold chain associated with conventional vaccines • Lyophilized yeast powder can be a simple way for long-term storage of immunogen(s) • Protease deficient strain is important for whole recombinant yeast-based vaccines

New approaches are needed to treat bacterial biofilm infections, particularly those of Pseudomonas aeruginosa (PA), which have high rates of antimicrobial resistance and are commonly found in chronic wound and cystic fibrosis lung infections. Combination therapeutics that act synergistically can overcome resistance; however, the delivery of multiple therapeutics at relevant dosages remains a challenge. We therefore developed a new nanoscale drug carrier for antimicrobial co-delivery by combining approaches from polyelectrolyte nanocomplex (NC) formation and layer-by-layer electrostatic self-assembly. This strategy led to NC drug carriers loaded with tobramycin antibiotics and antimicrobial silver nanoparticles (AgTob-NCs). AgTob-NCs displayed synergistic enhancements in antimicrobial activity against both planktonic and biofilm PA cultures, with positively charged NCs leading to complete biofilm eradication. NCs were evaluated in mouse models of lung infection, leading to reduced bacterial burden and improved survival outcomes. This approach therefore shows promise for nanoscale therapeutic co-delivery to overcome antimicrobial resistant bacterial infections.

Currently, there are no biological approaches to accelerate bone fracture repair. Osteobiologics that promote endochondral ossification are an exciting alternative to surgically implanted bone grafts, however, the translation of osteobiologics remains elusive because of the need for localized and sustained delivery that is both safe and effective. In this regard, an injectable system composed of hydrogel-based microparticles designed to release osteobiologics in a controlled and localized manner is ideal in the context of bone fracture repair. Here, we describe poly (ethylene glycol) dimethacrylate (PEGDMA)-based microparticles, in the form of microrods, engineered to be loaded with beta nerve growth factor (β-NGF) for use in a murine tibial fracture model. In-vitro studies demonstrated that protein-loading efficiency is readily altered by varying PEGDMA macromer concentration and that β-NGF loaded onto PEGDMA microrods exhibited sustained release over a period of 7 days. In-vitro bioactivity of β-NGF was confirmed using a tyrosine receptor kinase A (Trk-A) expressing cell line, TF-1. Moreover, TF-1 cell proliferation significantly increased when incubated with β-NGF loaded PEGDMA microrods versus β-NGF in media. In-vivo studies show that PEGDMA microrods injected into the fracture calluses of mice remained in the callus for over 7 days. Importantly, a single injection of β-NGF-loaded PEGDMA microrods resulted in significantly improved fracture healing as indicated by significant increases in bone volume, trabecular connective density, and bone mineral density and a significant decrease in cartilage despite a remarkably lower dose (∼111 fold) than the β-NGF in media. In conclusion, we demonstrate a novel and translational method of delivering β-NGF via injectable PEGDMA microrods to improve bone fracture repair.

Thermolabile nature of commercially available vaccines necessitates their storage, transportation and dissemination under refrigerated condition. Maintenance of continuous cold chain at every step increases the final cost of vaccines. Any breach in the cold chain, even for a short duration results in the need to discard the vaccine. As a result, there is a pressing need for the development of thermostable vaccines. In this proof of concept study, we showed that E. coli curli-GFP fusion protein remains stable in freeze-dried yeast powder for more than a 13 and 6 months when stored at 30 °C and 37 °C respectively. Stability of the heterologous protein remains unaffected during the process of heat-inactivation and lyophilization. The mass of lyophilized yeast powder remains almost unchanged during the entire period of storage. Expressed protein remains intact even after two cycles of freeze and thaws. The protease deficient strain appears ideal for the development of whole recombinant yeast-based vaccines. The cellular abundance of expressed antigen in dry powder after a year was comparable to freshly lyophilized cells. SEM microscopy showed the intact nature of cells in powdered form even after a year of storage at 30 °C. Observation made in this study showed that freeze-dry yeast powder can play a vital role in the development of thermostable vaccines.