[Research Status of Nanomaterial Medical Device and Discussion on Biological Evaluation].

In recent years, China has made great progress in basic nanomedicine, nanotoxicology and nanobiology research. Nanotechnology has been continuously applied in biomaterial and medical device, more and more medical devices applying nanomaterials are developed and manufactured. In order to gain more comprehension and accurate understanding of the research and industrial development in nanobiomaterial medical devices, this study reviewed the common nanomaterial in medical devices and the regulatory situation of nanomaterial medical devices at home and abroad, and discussed the current challenges in biological evaluation of nanomaterial medical devices, with a view to providing ideas for the safety evaluation and research of related products.

Safety and tissue remodeling assay of small intestinal submucosa meshes using a modified porcine surgical hernia model.

In studies to date, meshes based on extracellular matrix (ECM) have been extensively used in clinical applications. Unfortunately, little is known about the function of the immunogenic residual, absorbable profile during the tissue repair process. Moreover, there needs to be a recognized preclinical animal model to investigate the safety and efficacy of extracellular matrix meshes. Herein, we designed and fabricated a kind of SIS mesh followed by a scanned electron micrograph characterization and tested α-Gal antigen clearance rate and DNA residual. In order to prove the biocompatibility of the SIS mesh, cell viability, chemotaxis assay and local tissue reaction were assessed by MTT and RTCA cytotoxicity test in vitro as well as implantation and degradation experiments in vivo. Furthermore, we developed a stable preclinical animal model in the porcine ventral hernia repair investigation, which using laparoscopic plus open hybridization method to evaluate tissue adhesion, explant mechanical performance, and histologic analysis after mesh implantation. More importantly, we established a semi-quantitative scoring system to examine the ECM degradation, tissue remodeling and regeneration in the modified porcine surgical hernia model for the first time. Our results highlight the application prospect of the improved porcine ventral hernia model for the safety and efficacy investigation of hernia repair meshes.

Dose- and time-dependent systemic adverse reactions of sodium carboxy methyl cellulose after intraperitoneal application in rats.

Sodium carboxy methyl cellulose (SCMC) is an important absorbable biomaterial for anti-adhesion and hemostasis medical devices used in the abdominal cavity. However, the systemic toxicity of SCMC following intraperitoneal route has not been revealed sufficiently. Three SCMC solutions with gradient concentrations were intraperitoneally injected into 3 groups of rats with the doses of 50 mg/kg, 320 mg/kg and 2000 mg/kg respectively all at once to observe the dose-dependence of systemic reactions of SCMC and 10 rats (5 rats per sex) of each group were sacrificed 3 days, 7 days, 28 days and 90 days after injection to evaluate the time-dependence of the reactions. A range of adverse effects were shown in rats of the high-dose group which were found varied with time extending and virtually disappeared 90 days after injection. Slight reactions were observed in the medium-dose group while negligible effects were found in the low-dose group. The intraperitoneal application of SCMC can induce reversible systemic adverse effects to rats at the dose higher than 320 mg/kg and it is essential to take both dose- and time-dependent effects into account while designing a systemic toxicity study for absorbable biomaterials.

A novel method for evaluating the dynamic biocompatibility of degradable biomaterials based on real-time cell analysis.

Degradable biomaterials have emerged as a promising type of medical materials because of their unique advantages of biocompatibility, biodegradability and biosafety. Owing to their bioabsorbable and biocompatible properties, magnesium-based biomaterials are considered as ideal degradable medical implants. However, the rapid corrosion of magnesium-based materials not only limits their clinical application but also necessitates a more specific biological evaluation system and biosafety standard. In this study, extracts of pure Mg and its calcium alloy were prepared using different media based on ISO 10993:12; the Mg2+ concentration and osmolality of each extract were measured. The biocompatibility was investigated using the MTT assay and xCELLigence real-time cell analysis (RTCA). Cytotoxicity tests were conducted with L929, MG-63 and human umbilical vein endothelial cell lines. The results of the RTCA highly matched with those of the MTT assay and revealed the different dynamic modes of the cytotoxic process, which are related to the differences in the tested cell lines, Mg-based materials and dilution rates of extracts. This study provides an insight on the biocompatibility of biodegradable materials from the perspective of cytotoxic dynamics and suggests the applicability of RTCA for the cytotoxic evaluation of degradable biomaterials.

[Study of collagen sponge extracts on mouse splenic lymphocyte transformation in vitro].

Immunogenicity for medical devices of animal origin is the key and difficult point during immune safety evaluation for these devices. This paper firstly investigated the effect of collagen sponge of animal origin on mouse splenic lymphocyte transformation and proliferation, and then analyzed the influence factors on the MTT method and CFSE method. The results showed that collagen sponge extract cannot significantly induce transformation and proliferation of mouse splenic lymphocyte in vitro.

Hepatitis B virus core protein enhances human telomerase reverse transcriptase expression and hepatocellular carcinoma cell proliferation in a c-Ets2-dependent manner.

Hepatitis B virus core protein can regulate viral replication and host gene expression. However, it is unclear whether and how hepatitis B virus core protein regulates hepatocellular carcinoma cell proliferation. Induction of hepatitis B virus core protein over-expression significantly enhanced the proliferation of hepatocellular carcinoma cells, while knockdown of hepatitis B virus core protein expression inhibited the proliferation of hepatocellular carcinoma cells. Altered hepatitis B virus core protein expression significantly changed the growth of implanted hepatocellular carcinoma in vivo. Microarray analysis indicated that hepatitis B virus core protein up-regulated human telomerase reverse transcriptase expression, which was further validated by over-expression and knockdown assays in vitro. Furthermore, knockdown of human telomerase reverse transcriptase expression mitigated the hepatitis B virus core protein-enhanced hepatocellular carcinoma cell proliferation and clone formation in vitro. Luciferase assays indicated that hepatitis B virus core protein enhanced the promoter activity of human telomerase reverse transcriptase, which was dependent on the binding of c-Ets2 to the promoter region between -192 and -187. In addition, hepatitis B virus core protein enhanced human telomerase reverse transcriptase transcription in HepG2 cells, but not in the c-Ets2-silencing HepG2 cells. Moreover, hepatitis B virus core protein promoted c-Ets2 nuclear translocation. Finally, significantly higher levels of human telomerase reverse transcriptase expression and nuclear c-Ets2 accumulation were detected in hepatitis B virus core protein-positive hepatocellular carcinoma samples. Our findings demonstrate that hepatitis B virus core protein promotes hepatocellular carcinoma cell proliferation by up-regulating the c-Ets2-dependent expression of human telomerase reverse transcriptase.

Increased expression of T cell immunoglobulin- and mucin domain-containing molecule-3 on natural killer cells in atherogenesis.

OBJECTIVE: Atherosclerosis (AS) has many features of a chronic inflammatory disease in which both adaptive and innate immune cells play roles. Increasing evidence has demonstrated the impairment of circulating natural killer (NK) cells in atherosclerosis. However, the mechanisms of this impairment remain unclear. We previously reported the suppression of NK cell functions by T cell immunoglobulin- and mucin domain-containing molecule (Tim)-3. Here, we investigated the expression of Tim-3 on NK cells and assessed its possible roles in NK loss during atherogenesis. METHODS AND RESULTS: Flow cytometry analysis showed increased Tim-3 expression on peripheral NK cells from patients with AS. This increased expression of Tim-3 was significantly related to the levels of serum lipids and inflammation markers, C-reactive protein (CRP) and tumor necrosis factor (TNF)-α, which are risk factors for atherogenesis. We detected decreased peripheral NK cell number in patients with AS. The NK cell number showed significant inverse correlations with Tim-3 expression levels on NK cells and the level of serum TNF-α. Consistently, Tim-3 overexpression reduced NK92 cell number. Blockade of Tim-3 protected NK92 cells from TNF-α-induced cell death. Similar results were obtained with peripheral NK cells from patients with AS. CONCLUSIONS: To the best of our knowledge, for the first time, the data from our study provide evidence that augmented Tim-3 expression on NK cells plays an important role in NK cell loss in atherosclerosis. The augmented Tim-3 expression on NK cells might be used as an indicator for disease progression.