Murine RAW 264.7 cell line as an immune target: are we missing something?

The summary of the most important cell-biomaterial interactions that need to be considered during in vitro biocompatibility testing of bone scaffolds for tissue engineering applications

Tissue engineered products (TEPs), which mean biomaterials containing either cells or growth factors or both cells and growth factors, may be used as an alternative to the autografts taken directly from the bone of the patients. Nevertheless, the use of TEPs needs much more understanding of biointeractions between biomaterials and eukaryotic cells. Despite the possibility of the use of in vitro cellular models for initial evaluation of the host response to the implanted biomaterial, it is observed that most researchers use cell cultures only for the evaluation of cytotoxicity and cell proliferation on the biomaterial surface, and then they proceed to animal models and in vivo testing of bone implants without fully utilizing the scientific potential of in vitro models. In this review, the most important biointeractions between eukaryotic cells and biomaterials were discussed, indicating molecular mechanisms of cell adhesion, proliferation, and biomaterial-induced activation of immune cells. The article also describes types of cellular models which are commonly used for biomaterial testing and highlights the possibilities and drawbacks of in vitro tests for biocompatibility evaluation of novel scaffolds. Finally, the review summarizes recent findings concerning the use of adult mesenchymal stem cells for TEP generation and compares the potential of bone marrow- and adipose tissue-derived stem cells in regenerative medicine applications.

Cellular Behavior of RAW264.7 Cells in 3D Poly(ethylene glycol) Hydrogel Niches

Although macrophages undergo dynamic cellular responses in diverse extracellular environments, macrophage research has mostly relied on conventional culture methodologies such as two-dimensional and suspension cultures. In contrast, recent efforts have revealed evidence of the characteristic cellular behaviors of macrophages in actual tissues using a three-dimensional (3D) culture matrix. In this work, we exploited a poly(ethylene glycol)-based hydrogel as a macrophage culture matrix and observed cellular behaviors in 3D by manipulating the matrix properties. In the 3D microenvironment, macrophage-like RAW264.7 cells proliferated and formed spherical clusters by degrading the surrounding hydrogel network. Interestingly, we observed the significant upregulation of matrix metalloproteinases (MMPs) (i.e., MMP9 and MMP14) as well as M1 polarization markers (i.e., iNOS, COX2, TNF-α) in 3D, whereas M2 polarization markers (i.e., CD206, Arg1, TGF-β) were downregulated. Specifically, the expressions of both M1 and M2 markers were simultaneously increased in a stiff matrix compared to those of a soft matrix. In addition, matrix degradability significantly influenced the TNF-α secretion of encapsulated RAW264.7 cells. The MMP sensitivity of the hydrogel decreased TNF-α expression in a soft matrix, whereas it upregulated TNF-α in a stiff matrix compared to those of MMP-insensitive hydrogel. These findings suggest that the highly tunable poly(ethylene glycol) hydrogels can dictate macrophage behavior by altering the surrounding 3D microenvironment.

EGFR inhibitors from cancer to inflammation: Discovery of 4-fluoro-N-(4-(3-(trifluoromethyl)phenoxy)pyrimidin-5-yl)benzamide as a novel anti-inflammatory EGFR inhibitor

EGFR inhibitors are well-known as anticancer agents. Quite differently, we report our effort to develop EGFR inhibitors as anti-inflammatory agents. Pyrimidinamide EGFR inhibitors eliciting low micromolar IC₅₀ and the structurally close non-EGFR inhibitor urea analog were synthesized. Comparing their nitric oxide (NO) production inhibitory activity in peritoneal macrophages and RAW 246.7 macrophages indicated that their anti-inflammatory activity in peritoneal macrophages might be a sequence of EGFR inhibition. Further evaluations proved that compound 4d significantly and dose-dependently inhibits LPS-induced iNOS expression and IL-1β, IL-6, and TNF-α production via NF-κB inactivation in peritoneal macrophages. Compound 4d might serve as a lead compound for development of a novel class of anti-inflammatory EGFR inhibitors.

Rapid synthesis and immunogenicity of mycobacterial (1→5)-α-d-arabinofuranan

A rapid synthesis of the α(1→5) arabinofuranan polysaccharides, found on the outer surface of Mycobacterium tuberculosis (Mtb), is achieved by a regio- and stereocontrolled ring opening polymerization of β-d-arabinofuranose-1,2,5-orthobenzoate. The robust polymerization reaction allows the incorporation of an amine linker, which was used to conjugate with protein tetanus toxoid (TT) to further investigate its adjuvant activities. The synthetic arabinan, which is the glycan on the non-reducing end of Mtb lipoarabinomannan (LAM), was evaluated for its immunological properties in vitro and in vivo. Systemic inflammation and the promotion of innate immune response were observed in macrophages treated with the synthetic arabinan as an adjuvant through an increase in the production of TNF-α and IL-12. In vivo evaluation of IFN-γ, IL-2, and TNF-α productions in mice pre-immunized with the synthetic arabinan conjugated TT indicated great enhancements of the immunological responses when compared to that of TT alone.

Analysis of Metabolites in White Flowers of Magnolia Denudata Desr. and Violet Flowers of Magnolia Liliiflora Desr

A total of seven phenolics and 44 metabolites was profiled in white flowers of Magnolia denudata and violet flowers of Magnolia liliiflora using high-performance liquid chromatography (HPLC), electrospray ionization-mass spectrometry (ESI-MS), and gas chromatography time-of-flight mass spectrometry (GC-TOFMS). Seven phenylpropanoid compounds were identified in white flowers by liquid chromatography mass spectrometry (LC-MS). An HPLC analysis showed that phenylpropanoid accumulation in violet flowers was 1.48 times higher than that in white flowers. Furthermore, superoxide dismutase (SOD)-like activity and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity were determined to investigate the antioxidant properties of secondary metabolites in different flowers. Violet flowers showed higher SOD-like and DPPH activity than white flowers. In addition, anti-inflammatory activity measured using a nitric oxide assay was higher in violet flowers than in white flowers. Our results provide valuable information on the relationship between primary and secondary metabolites, and synergistic antioxidant and anti-inflammatory properties derived from phenolic compounds in different colored flowers.

Protection of silver nanoparticles using Eysenhardtia polystachya in peroxide-induced pancreatic β-Cell damage and their antidiabetic properties in zebrafish

Background

The aim was to explore the efficacy of extract of Eysenhardtia polystachya-loaded silver nanoparticles (EP/AgNPs) on pancreatic β cells, INS-1 cells, and zebrafish as a valuable model for the study of diabetes mellitus.

Materials and methods

EP/AgNPs were synthesized using methanol/water bark extract of E. polystachya and characterized using various physicochemical techniques.

Results

Immersion of adult zebrafish in 111 mM glucose solution resulted in a sustained hyperglycemic, hyperlipidemic state, and serum insulin levels decreased. The synthesized EP/AgNPs showed an absorption peak at 413 nm on ultraviolet–visible spectroscopy, revealing the surface plasmon resonance of the nanoparticles. Transmission electron microscopy indicated that most of the particles were spherical, with a diameter of 10–12 nm, a polydispersity index of 0.197, and a zeta potential of −32.25 mV, suggesting high stability of the nanoparticles. EP/AgNPs promote pancreatic β-cell survival, insulin secretion, enhanced hyperglycemia, and hyperlipidemia in glucose-induced diabetic zebrafish. EP/AgNPs also showed protection of the pancreatic β-cell line INS-1 against hydrogen peroxide-induced oxidative injury.

Conclusion

The results indicate that EP/AgNPs have good antidiabetic activity and therefore could be used to prevent the development of diabetes.