Biocompatibility study of tobacco mosaic virus nanoparticles on human alveolar bone cells.

One of the most important factors in a dental implant's success is an adequate quantity of supporting bone. However, there are still some limitations for the bone substitution material. Previous studies found that tobacco mosaic virus (TMV) had the potential for bone formation induction. The aim of this study was to evaluate the biocompatibility of TMV with primary human alveolar bone cells. Primary human alveolar bone cells were cultured on TMV coated substrates. Cell viability, alkaline phosphatase activity, calcium matrix mineralization forming ability, immunofluorescence staining for osteocalcin synthesis and cell morphology were assessed. The results showed that primary human alveolar bone cells cultured on the TMV coated substrates had a higher metabolic rate than the non-TMV coated control group at days 1, 3, 7 and 14. Moreover, the calcium deposition was positive and the alkaline phosphatase activity assay was found significantly greater than the control group at day 14 (p < 0.05). The osteocalcin protein synthesis was found in both the TMV coated substrates and the control group. The immunofluorescence study revealed that in the TMV coated substrates group, the cell morphology changed into a polygonal shape and aggregated more quickly than the control group. The present findings conclude that TMV is biocompatible with primary human alveolar bone cells and also shows osteoinduction potential.

Utilization of a mask fitter or micropore tape to improve the fit of a surgical mask.

PURPOSE: This study aimed to test the face seal of a surgical mask modified using a custom-made mask fitter or by sealing all borders with micropore tape, in comparison to the N95 mask as a gold standard. METHODS: Fifteen participants were assigned to wear an N95 mask, a surgical mask sealed with a mask fitter, and a surgical mask sealed with micropore tape. A quantitative fit test was performed using a Portacount respirator fit tester in 4 different actions: bending over, talking, moving the head from side to side, and moving the head up and down. RESULTS: The N95 showed the highest overall fit factor score (134.67 ± 66.62), passing Occupational Safety and Health Administration (OSHA) standards. The surgical mask alone had the lowest overall fit factor score of 4.73 ± 3.30. Modification of the surgical mask using a mask fitter or micropore tape significantly increased the overall fit factor to 35.33 ± 14.58 and 29.33 ± 9.73, respectively. This pattern was similar for all exercises. CONCLUSION: The N95 was the only mask type that passed the OSHA standard for protection. Use of a mask fitter or micropore tape significantly increased the face seal of a surgical mask. This could offer useful levels of protection during a non-aerosol dental procedure.

Biocompatibility study of modified injectable hyaluronic acid hydrogel with mannitol/BSA to alveolar bone cells.

The quality and quantity of bone are crucial to the success of dental implant treatment. Recently, bone grafting materials have reached some limitations. This study aimed to evaluate the biocompatibility of novel drug delivery material, injectable methacrylated hyaluronic acid hydrogel incorporated with different ratios of mannitol and BSA (Man/BSA MeHA), to human alveolar bone cells. The three-dimensionally encapsulated cell culture was evaluated with the resazurin cell viability test, alkaline phosphatase activity assay, immunohistochemistry test for collagen type-I synthesis, and cell morphology. The results showed that the encapsulated cells were viable in all four ratios of Man/BSA MeHA hydrogel and the average metabolic rate was not less than the control group. The morphology test showed round shape cells at the upper portion of the hydrogel and fibroblast-like or polygonal shape at the lower portion of hydrogel next to the culture plate. All four groups could express enzyme alkaline phosphatase and collagen type-I. In conclusion, four ratios of Man/BSA MeHA hydrogel were biocompatible with primary human alveolar bone cells.

Correlation between extent of osteolytic damage and metastatic burden of human breast cancer metastasis in nude mice: real-time PCR quantitation.

Orthotopic or intracardiac injection of human breast cancer cell lines into immunocompromised mice allows study of the molecular basis of breast cancer metastasis. We have established a quantitative real-time PCR approach to analyze metastatic spread of human breast cancer cells inoculated into nude mice via these routes. We employed MDA-MB-231 human breast cancer cells genetically tagged with a bacterial beta-galactosidase (Lac-Z) retroviral vector, enabling their detection by TaqMan real-time PCR. PCR detection was linear, specific, more sensitive than conventional PCR, and could be used to directly quantitative metastatic burden in bone and soft organs. Attesting to the sensitivity and specificity of the PCR detection strategy, as few as several hundred metastatic MDA-MB-231 cells were detectable in 100 microns segments of paraffin-embedded lung tissue, and only in samples adjacent to sections that scored positive by histological detection. Moreover, the measured real-time PCR metastatic burden in the bone environment (mouse hind-limbs, n = 48) displayed a high correlation to the degree of osteolytic damage observed by high resolution X-ray analysis (r2 = 0.972). Such a direct linear relationship to tumor burden and bone damage substantiates the so-called 'vicious cycle' hypothesis in which metastatic tumor cells promote the release of factors from the bone which continue to stimulate the tumor cells. The technique provides a useful tool for molecular and cellular analysis of human breast cancer metastasis to bone and soft organs, can easily be extended to other cell/marker/organ systems, and should also find application in preclinical assessment of anti-metastatic modalities.

Role of HMGB1 in proliferation and migration of human gingival and periodontal ligament fibroblasts.

High mobility group box 1 (HMGB1) was originally defined as a nuclear protein. However, later studies showed that HMGB1 was released from damaged cells into the extracellular milieu and functioned as a danger signaling molecule. HMGB1 has also been shown to exert proliferative and chemoattractant effects on many cell types. In this study, we investigated the in vitro effect of human recombinant HMGB1 on the proliferation and migration of human gingival fibroblasts (HGF) and human periodontal ligament fibroblasts (HPDLF). For the proliferation assay, HGF and HPDLF were cultured in the presence of 5, 10, and 50 ng/mL HMGB1. After a period of 6 days, cell proliferation was determined by MTT assay. The migration assay was performed by culturing the two cell types in Transwells with HMGB1 in the lower chamber as a chemoattractant. Cell migration during 16 h was determined by crystal violet staining of the cells that migrated across the membrane. The results showed that HMGB1, at 50 ng/mL, was able to significantly induce proliferation of HGF by up to 171.4 ± 17.1%. No such proliferation induction was seen for HPDLF. In the migration assay, however, 100 ng/mL HMGB1 induced migration of both cell types. The counts of cells that migrated across the membrane, as compared with the control, were increased to 273 ± 24.1% and 410.3 ± 158% for HGF and HPDLF, respectively. Since proliferation and migration are basic abilities of cells required for proper tissue repair, these data suggest that HMGB1 plays an important role in these functions of periodontal cells.

Evaluation of biomimetic scaffold of gelatin-hydroxyapatite crosslink as a novel scaffold for tissue engineering: biocompatibility evaluation with human PDL fibroblasts, human mesenchymal stromal cells, and primary bone cells.

Biomimetic gelatin (gel)-hydroxyapatite (HA) composites have been prepared for studying hard tissue engineering scaffolds. However, the biocompatibility test of this form of material using these three cell types, which are periodontal ligament (PDL) fibroblast cells, human mesenchymal stromal cells (HMSc) and primary cells from human hip bone (HBc) has never been evaluated. The objective of this article is to prepare and evaluate the biocompatibility of gel-HA crosslinked scaffold for tissue engineering. Two different scaffolds were prepared: preparation (1), 2.5% gel/2.5% HA; preparation (2), 2.5% gel/5% HA. Three cell types including PDL, HMSc, and HBc were used. Assessment of biocompatibility and osteoblastic cellular responses was evaluated using a three-dimensional cell culture method and scanning electron microscopy (SEM). From SEM, it was observed that scaffold (1) exhibits stable porous formation with well-blended and dispersed HA powder. All three cell types were able to proliferate in both scaffolds. The HMSc and HBc got attached to the scaffolds to a significantly higher degree and subsequently proliferated more than PDL. The alkaline phosphatase (ALP) activities of HMSc and HBc were stronger when cultured in scaffold (S1) than (S2). It was seen that the two scaffold preparations show good biocompatibility with all three cell types tested. The better cellular responses with scaffold (S1) than (S2) might be due to the different structural and morphological characteristics, that is, scaffold (S1) retained more small-sized apatite crystals and a better developed pore configuration than scaffold (S2). Based on these findings, the biomimetically synthesized composite scaffolds have the potential to be used in hard tissue regeneration and tissue engineering fields.

Doxycycline-inducible expression of SPARC/Osteonectin/BM40 in MDA-MB-231 human breast cancer cells results in growth inhibition.

SPARC (secreted protein acidic and rich in cysteine)/BM40/Osteonectin is a matricellular protein with multiple effects on cell behaviour. In vitro, its major known functions are anti-adhesive and anti-proliferative, and it is associated with tissue remodelling and cancer in vivo. SPARC is overexpressed in many cancers, including breast cancer, and the effects of SPARC seem to be cell type-specific. To study the effects of SPARC on breast cancer, we transfected SPARC into the MDA-MB-231 BAG, human breast cancer cell line using the Tet-On inducible system. By western analysis, we found low background levels in the MDA-MB-231 BAG and clone X parental cells, and prominent induction of SPARC protein expression after doxycycline treatment in SPARC transfected clones X5, X21, X24 and X75. Induction of SPARC expression did not affect cell morphology or adhesiveness to collagens type I and IV, but it slowed the rate of proliferation in adherent cultures. Cell cycle analysis showed that SPARC slowed the progression to S phase. Doxycycline induction of SPARC also slowed the rate of monolayer wound closure in the cultured wound healing assay. Thymidine inhibition of proliferation abrogated this effect, confirming that it was due to anti-proliferation rather than inhibition of migration. Consistent with this, we were unable to detect any differences in migration and Matrigel outgrowth analysis of doxycycline-stimulated cells. We conclude that SPARC is inhibitory to human breast cancer cell proliferation, and does not stimulate migration, in contrast to its stimulatory effects reported for melanoma (proliferation and migration) and glioma (migration) cells. Similar growth repression by SPARC has been reported for ovarian cancer cells, and this may be a common feature among carcinomas.