In vitro development and optimization of cell-laden injectable bioprinted gelatin methacryloyl (GelMA) microgels mineralized on the nanoscale

Bone defects may occur in different sizes and shapes due to trauma, infections, and cancer resection. Autografts are still considered the primary treatment choice for bone regeneration. However, they are hard to source and often create donor-site morbidity. Injectable microgels have attracted much attention in tissue engineering and regenerative medicine due to their ability to replace inert implants with a minimally invasive delivery. Here, we developed novel cell-laden bioprinted gelatin methacrylate (GelMA) injectable microgels, with controllable shapes and sizes that can be controllably mineralized on the nanoscale, while stimulating the response of cells embedded within the matrix. The injectable microgels were mineralized using a calcium and phosphate-rich medium that resulted in nanoscale crystalline hydroxyapatite deposition and increased stiffness within the crosslinked matrix of bioprinted GelMA microparticles. Next, we studied the effect of mineralization in osteocytes, a key bone homeostasis regulator. Viability stains showed that osteocytes were maintained at 98 % viability after mineralization with elevated expression of sclerostin in mineralized compared to non-mineralized microgels, showing that mineralization can effectively enhances osteocyte maturation. Based on our findings, bioprinted mineralized GelMA microgels appear to be an efficient material to approximate the bone microarchitecture and composition with desirable control of sample injectability and polymerization. These bone-like bioprinted mineralized biomaterials are exciting platforms for potential minimally invasive translational methods in bone regenerative therapies.

In vitro development and optimization of cell-laden injectable bioprinted gelatin methacryloyl (GelMA) microgels mineralized on the nanoscale

Bone defects may occur in different sizes and shapes due to trauma, infections, and cancer resection. Autografts are still considered the primary treatment choice for bone regeneration. However, they are hard to source and often create donor-site morbidity. Injectable microgels have attracted much attention in tissue engineering and regenerative medicine due to their ability to replace inert implants with a minimally invasive delivery. Here, we developed novel cell-laden bioprinted gelatin methacrylate (GelMA) injectable microgels, with controllable shapes and sizes that can be controllably mineralized on the nanoscale, while stimulating the response of cells embedded within the matrix. The injectable microgels were mineralized using a calcium and phosphate-rich medium that resulted in nanoscale crystalline hydroxyapatite deposition and increased stiffness within the crosslinked matrix of bioprinted GelMA microparticles. Next, we studied the effect of mineralization in osteocytes, a key bone homeostasis regulator. Viability stains showed that osteocytes were maintained at 98% viability after mineralization with elevated expression of sclerostin in mineralized compared to non-mineralized microgels, indicating that mineralization effectively enhances osteocyte maturation. Based on our findings, bioprinted mineralized GelMA microgels appear to be an efficient material to approximate the bone microarchitecture and composition with desirable control of sample injectability and polymerization. These bone-like bioprinted mineralized biomaterials are exciting platforms for potential minimally invasive translational methods in bone regenerative therapies.

Nanostrategies to Develop Current Antiviral Vaccines

Infectious diseases are a worldwide concern. They are responsible for increasing the mortality rate and causing economic and social problems. Viral epidemics and pandemics, such as the COVID-19 pandemic, force the scientific community to consider molecules with antiviral activity. A number of viral infections still do not have a vaccine or efficient treatment and it is imperative to search for vaccines to control these infections. In this context, nanotechnology in association with the design of vaccines has presented an option for virus control. Nanovaccines have displayed an impressive immune response using a low dosage. This review aims to describe the advances and update the data in studies using nanovaccines and their immunomodulatory effect against human viruses.

Enterococcus faecalis and Staphylococcus aureus stimulate nitric oxide production in macrophages and fibroblasts in vitro

Aim: Nitric oxide (NO) is an important mediator related to damage of the pulp tissue and at the same time to regenerative pulp processes. However, it is not clear how common endodontic microorganisms can regulate this mediator. This study aimed to investigate NO production by macrophages and fibroblasts against Enterococcus faecalis- and Staphylococcus aureus-antigens. Methods: RAW 264.7 macrophages and L929 fibroblast cell lines were stimulated with different heat-killed (HK) antigen concentrations (105-108 colony forming units - CFU) from E. faecalis and S. aureus with or without interferon-gamma (IFN-γ). Cell viability by MTT colorimetric assay and NO production from the culture supernatants were evaluated after 72 h. Results: Data here reported demonstrated that none of the antigen concentrations decreased cell viability in macrophages and fibroblasts. The presence of HK-S. aureus and HK-E. faecalis antigen- stimulated NO production with or without IFN-γ on RAW 264.7. The HK-S. aureus antigen stimulated NO production in L929 fibroblasts with or without IFN-γ, and the highest concentration of HK-E. faecalis with IFN-γ also stimulated NO production by these cells. Conclusion: The amount of NO produced by macrophages and fibroblasts may be involved in the concentration and type of prevalent endodontic microorganisms, generating new answers for the understanding of pulpal revascularization/regeneration processes.