[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.

Cartilage-Inspired Inhomogeneous Salt-Hydrogel for Hydrated Drag-Reducing and Strain Sensing.

Articular cartilages exhibit load-bearing capacity and durability due to their inhomogeneous structure. Inspired by this unique structure, a tough and inhomogeneous salt-hydrogel was developed by trapping sodium acetate (NaAc) crystals in polyacrylamide (PAM) polymer networks and then partially redissolving the NaAc crystals. The compressive and tensile stresses of the salt-hydrogel increase significantly by more than 20 times when oversaturated Ac- and Na+ are introduced into the gel network. Such an enhancement in mechanical strength is primarily attributed to the formation of NaAc crystals within the gel network. Further investigations reveal that the mechanical strength of the salt-hydrogel is temperature-dependent as the NaAc crystals gradually redissolve in the gel network with increasing temperature. Furthermore, redissolving NaAc crystals in an aqueous solution can yield an inhomogeneous salt-hydrogel. The topmost soft surface of the salt-hydrogel offers hydration lubrication, while the inhomogeneous network confers load-bearing capacity and durability. Compared to regular hydrogels, the inhomogeneous salt-hydrogel surface can realize drag reduction and remain smooth without damage after the friction tests. Moreover, a salt-hydrogel coating is also fabricated to visually demonstrate its drag-reducing property. In addition, this salt-hydrogel possesses conductivity and can be utilized in the development of inhomogeneous salt-hydrogel fibers (diameter = 438 ± 7 µm) for strain detection. The produced salt-hydrogel fiber exhibits excellent durability and reproducibility as a strain sensor, capable of detecting both small strains (e.g., 1%) and large strains (e.g., 40%). This work provides fundamental insights into developing hydrogels with an inhomogeneous network and explores their potential applications (e.g., hydrated drag-reducing, strain sensing).

Oviposition by Plagiodera versicolora on Salix matsudana cv. 'Zhuliu' alters the leaf transcriptome and impairs larval performance.

Insect egg deposition can induce plant defenses against their larvae. Previous studies have primarily focused on herbaceous plant defenses; however, little is known about how the Salicaceae respond to insect egg deposition and defend themselves against herbivores. By combining plant defense gene studies and bioassays, we investigated the effect of the coleoptera Plagiodera versicolora egg deposition on willow (Salix matsudana cv. 'Zhuliu') and examined the interactions at the plant resistance and transcriptome levels. RNA-seq data were utilized to analyze changes in the leaf transcriptome with and without oviposition, and also the changes in the leaf transcriptome of feeding-damaged leaves with and without prior oviposition. P. versicolora oviposition on willow leaves resulted in altered expression levels of transcripts associated with plant stress and metabolic responses. Compared with leaves with no oviposition, leaves with egg deposition showed a slight increase in phenylpropanoid biosynthesis and phytohormone signaling genes after larval feeding. The RNA-seq analysis revealed alterations in willow transcripts in response to leaf beetle infestations. Bioassays indicated that oviposition by P. versicolora on willows reduced subsequent larvae performance, suggesting that prior oviposition by P. versicolora could increase willows' resistance to larvae. This study advances our knowledge of how oviposition by coleoptera insects induces changes in the resistance of leaves to herbivory in the Salicaceae family.

Mechanism of remodeling and local effects in vivo of a new injectable cosmetic filler.

By studying the local effects of a new type of injectable cosmetic filler implanted into the animal to explore the mechanism of remodeling and cosmetic effect of this kind of product. Take 12 rabbits and select 4 implantation points on both sides of the spine, respectively, and implant the test sample (PLLA) and negative control sample (HDPE) into the subcutaneous tissues on both sides. In the same way, take another 12 rabbits and implant the marketing control sample (cross-linked sodium hyaluronate) and negative control sample (HDPE) into the subcutaneous tissues on both sides. The animals were executed at 1 week, 4 weeks, 13 weeks and 52 weeks respectively, and Hematoxylin-Eosin staining, Masson trichrome staining and immunofluorescence staining were performed to characterize the local effects in vivo and the expression of type I collagen (Col. I), type III collagen (Col.III) and matrix metalloproteinase 9 (MMP-9). Good histocompatibility of the test sample and the marketing control sample were found. The foreign body reaction of marketing control sample was more intense than that of the test sample after 13 weeks. The foreign body reaction of testing sample was more intense after 52 weeks, while that of the marketing control sample was more stable. With the process of tissue repair, the collagen fibers of test samples and marketing control samples gradually increased after implantation. Type I collagen was mainly found inside the fiber capsule, while type III collagen was mainly found outside. The positive expression of matrix metalloproteinase 9 gradually increased, the positive expression of test samples increased significantly after 52 weeks, while that of marketing control samples did not change significantly. Good histocompatibility of PLLA filler is found. Matrix metalloproteinase 9 participates in foreign body reaction and collagen formation, which can reflect the process of tissue remodeling.

ECG-guided PICC insertion using a new silicon catheter with a conductive tip: A retrospective clinical study.

OBJECTIVE: Safety and efficacy of ECG-guided PICC insertion using a new silicon catheter with a conductive tip was evaluated in daily practice. METHODS: A retrospective study was conducted on 1659 patients who accepted successful tip-conductive PICC placement and clinically followed-up until the catheter removal between January 2018 and April 2019. Baseline of patient characteristics, catheter placement characteristics, date of dressing changes as well as records of catheter-related complications were extracted from a special designed mobile APP. RESULTS: The first-attempt success (success of placing catheter tip to the ideal position by primary indwelling operation) rate of PICC placement was 99.3%. The average duration of PICC placement was 128.7 ± 39.5 days and 1535 patients (92.5%) reached the therapy end-point without any complications and removed the catheter normally. The cumulative rates of total complications were 7.5%, including exit site infection (2.5%), phlebitis (0.9%), DVT (1.0%), catheter malposition (1.1%), catheter breakage (0.1%), and liquid extravasation (1.8%). In multivariable logistic regression analyses, hyperlipidemia, diabetes mellitus, lung cancer, stomach cancer, and lymphoma were significantly associated with increased risk of complications, as the independent risk factors. CONCLUSIONS: This retrospective clinical study demonstrates that ECG-guided insertion of a new tip-conductive PICC is associated with a high rate of first-attempt success and low rate of catheter related complications.

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.

[Current Progress on Biological Evaluation for Medical Devices].

To broadly understand the new direction of biological evaluation for medical devices, we introduced both domestic and international progress of biological evaluation and focused on illustrating the key points on full life-cycle biological evaluation, toxicological risk evaluation, evaluation endpoints and package material evaluation concern as well as how to use the update vision of ISO 10993-1:2018 scientifically and reasonably in order to provide us better services on performing biological evaluation for medical devices.

The suitability of reconstructed human epidermis models for medical device irritation assessment: A comparison of In Vitro and In Vivo testing results.

The ISO 10993 standards on biocompatibility assessment of medical devices discourage the use of animal tests when reliable and validated in vitro methods are available. A round robin validation study of in vitro reconstructed human epidermis (RhE) assays was performed as potential replacements for rabbit skin irritation testing. The RhE assays were able to accurately identify strong irritants in dilute medical device extracts. However, there was some uncertainty about whether RhE tissues accurately predicted the results of the rabbit skin patch or intracutaneous irritation test. To address that question, this paper presents in vivo data from the round robin and subsequent follow-up studies. The follow-up studies included simultaneous in vitro RhE model and in vivo testing of round robin polymer samples and the results of dual in vitro/in vivo testing of currently marketed medical device components/materials. Our results show for the first time that for both pure chemicals and medical device extracts the intracutaneous rabbit test is more sensitive to detect irritant activity than the rabbit skin patch test. The studies showed that the RhE models produced results that were essentially equivalent to those from the intracutaneous rabbit skin irritation test. Therefore, it is concluded that RhE in vitro models are acceptable replacements for the in vivo rabbit intracutaneous irritation test for evaluating the irritant potential of medical devices.

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.

The assessment of xenogeneic bone immunotoxicity and risk management study.

BACKGROUND: Xenogeneic bone has been widely used in a variety of clinical bone-related disease to promote bone healing and restore bone defects. However, the adverse effects of immune system limit its application in the clinic. The aim of this study was to evaluate xenogeneic bone safety of immunotoxicity and explore the methods for immune risk supervision. RESULTS: Xenogeneic bone, which is freeze-dried bovine cancellous bone, was implanted into the muscle of mice. On day 7, 14 and 28, the effects of xenogeneic bone were examined on humoral immunity and cellular immunity, including the levels of IgG, IgM, C3, inflammatory factors (TNF-α, IL-6), alkaline phosphatase (ALP) and the lymphocyte phenotype. The data showed that xenogeneic bone implantation had no potential to induce immune responses not only in humoral immunity but also in cellular immunity. To reveal the risk of immunogenicity, the residual DNA and the clearance of α-gal epitope were analyzed in 2 different bones (bone 1 is deproteinized bone, bone 2 is acellular and defatted bone). It was suggested that DNA of xenogeneic bone can be limited to < 50 ng per mg dry weight for the repair or regeneration with the acceptable immune risk. And α-gal clearance of xenogeneic bone could be an effective risk factor for improving xenograft quality management. CONCLUSIONS: Through the detection of xenogeneic bone immunotoxicity, our findings indicated that the supervisions of risk factors could contribute to reduce the immune risk. And the risk factors under the acceptable limitation could decrease or replace animal experiment. However, it still needs to be studied on the limitation of α-gal epitope to predict rejection of xenogeneic bone more accurately.

Hemocompatibility of biodegradable Zn-0.8 wt% (Cu, Mn, Li) alloys.

Zinc alloys have been explored as potential materials for biodegradable vascular stents due to their tolerable corrosion rates and tunable mechanical properties. However, the performances of Zn alloys were not supported with enough toxicity or biological compatibility evaluation, particularly hemocompatibility for vascular scaffolding application. In this work, the hemocompatibility of three zinc alloys (Zn-0.8Cu, Zn-0.8Mn and Zn-0.8Li) was evaluated with 316 L stainless steel and pure zinc as controls. The hemolysis ratios of 316 L stainless steel, pure Zn, Zn-0.8Cu, Zn-0.8Mn and Zn-0.8Li were 0.38 ±â€¯0.08%, 1.04 ±â€¯0.21%, 0.47 ±â€¯0.21%, 0.57 ±â€¯0.14% and 0.52 ±â€¯0.22%, respectively, for direct contact method. Platelets aggregation on the 316 L stainless steel was observed, while the adhered platelets on the Zn alloys exhibited round shape with few pseudopodia spreading. The number of adhered platelets on the three zinc alloys (Zn-0.8Cu, Zn-0.8Mn and Zn-0.8Li) had no statistically difference compared with 316 L stainless steel, while significant fewer than the pure Zn group. None remarkable platelet activation, hematocyte aggregation, coagulation or complement activation was observed in any Zn alloy group. Furthermore, the Zn alloys prolonged prothrombin time and partial thromboplastin time, demonstrating a potential function of anticoagulation. The results demonstrated that Zn alloys presented in this work are indeed meeting the hemocompatible requirements of implant and showing the promise for perspective application as biodegradable stent.

[Application of the Threshold of Toxicological Concern (TTC) to Biological Evaluation of Medical Devices].

The threshold of toxicological concern (TTC), a risk estimation method based on compound structurally-related toxicity data, has been widely used by many countries and regions for the safety risk assessment of food packaging materials and additives etc. Toxicological risk estimation is of importance in the biological evaluation of medical devices. Application of the TTC approach to leachable from medical devices may reduce or replace some unnecessary biocompatibility tests, but consideration should be taken for contact duration and route differences, which could affect the applicability of TTC. We herein focused on analyzing the eligibility of TTC for its further application in biological evaluation of medical devices.

TLR4 increases the stemness and is highly expressed in relapsed human hepatocellular carcinoma.

Toll-like receptor 4 (TLR4) plays an essential role in cancer progress. Here, we find that the expression of TLR4 in relapsed human hepatocellular carcinoma (HCC) clinical samples is higher than that in the non-relapsed ones, which leads us to explore the role of TLR4 in cancer stemness. We reported that TLR4-AKT signaling pathway was activated by lipopolysaccharides (LPS) in HCC cell lines to enhance the cancer stemness capacity, which was reflected by the increased percentage of CD133+ CD49f+ population and side population, enhanced sphere formation, and the upregulation of stemness marker gene-SOX2. Downregulation of SOX2 attenuated the enhanced HCC stemness induced by LPS, indicating SOX2 as a downstream mediator of LPS-TLR4 signaling. The role of LPS-TLR4 signaling in inducing HCC stemness was further confirmed by tumor xenograft experiment in vivo. Taken together, our findings provide a novel therapeutic target to prevent the recurrence of HCC.

Reverse Remodeling of Pulmonary Arterioles After Pulmonary Artery Banding in Patients ≥ 2 Years Old with Severe Pulmonary Arterial Hypertension and Congenital Heart Disease.

The purpose of this study was to evaluate the pathological changes of the pulmonary arterioles in patients ≥ 2 years of age who first underwent a pulmonary artery banding (PAB) procedure, followed by bidirectional Glenn or Fontan according to their specific conditions. This was a prospective study of 15 children diagnosed and treated with PAB at the Department of Cardiothoracic Surgery of Anzhen Hospital between January 2009 and December 2012. The percentage of media area (%MS) of pulmonary arteriole, the percentage of media thickness (%MT), and pulmonary arterial density (APSC) were calculated from lung tissue sections. Pulmonary artery pressure decreased significantly after PAB surgery (P < 0.01). Postoperative mean pulmonary artery pressure declined significantly (P < 0.01), the cardiothoracic ratio was reduced (P < 0.05), and percutaneous oxygen saturation (inhaled air) decreased to 80-85% (P < 0.01). %MT (from 35.1 ± 5.6% to 26.9 ± 4.3%, P < 0.01), %MS (from 51.4 ± 6.7% to 32.2 ± 7.4%, P < 0.01), and APSC (from 108.3 ± 38.5 to 83.6 ± 19.6, P < 0.01) were decreased significantly after PAB. Five patients underwent the bidirectional Glenn procedure and four underwent Fontan. In conclusion, the results suggest that PAB can reduce pulmonary artery pressure and that pulmonary arterial lesions can be reversed after PAB.

Prognostic evaluation of NANOG and OCT4 expression for posttransplantation hepatocellular carcinoma recurrence.

Postoperative hepatocellular carcinoma (HCC) recurrence and metastasis throw great threaten to its overall survival (OS). This paper focus on exploring the prognostic significance of NANOG and OCT4 expression in HCC recurrence and OS after liver transplantation. Eighty-six patients who meet University of California San Francisco (UCSF) criteria and underwent liver transplantation in Tianjin First Central Hospital between August 2010 and August 2013 were included. Expression of NANOG and OCT4 was determined by immunohistochemistry. The relationships between NANOG and OCT4 expression with tumor recurrence, tumor count, histology stage, lymph node metastasis (LNM) and microvascular invasion (MVI) were explored through the χ2 test and Cox regression analysis. We found that 19/26 and 20/24 patients with positive expression of NANOG and OCT4 relapsed. Combination of NANOG and OCT4 expression was indicated as valuable prognostic signature for HCC recurrence prediction (P < 0.0011). Besides, we identified other key factors with significant correlations with recurrence, such as LNM (P = 0.011) and MVI (P = 0.024). Strikingly, recurrence sites could significantly affect recurrence time (P = 0.0062) and patients with recurrence in transplanted liver have longer recurrence time. In conclusions, we analyzed the relationships between NANOG/OCT4 expression, clinicopathology features, HCC recurrence, and OS after liver transplantation for the first time. Combination of NANOG, OCT4, LNM, histopathological stage, and MVI may be predictor for HCC recurrence posttransplantation. Comprehensive of histopathological stage grade and LNM were considered as prognosis factor for OS after liver transplantation. This should be helpful for treatment method selection for HCC patients after liver transplantation.

Hemocompatibility assay of a micro-catheter using hydrophilic coating biomaterials.

For medical devices directly or indirectly contacted with blood, hemocompatibility assay is of great importance during the biological evaluation. In ISO 10993-4:2017 - Biological evaluation of medical devices part 4, a selection of tests for interactions with blood is given with the rationale for selection of tests based on their intended use specified, however, the specific testing protocols may vary significantly when performing the hemocompatibility assays. In recent years, medical catheters have been widely used in clinical practice. Moreover, a lot of surface modified catheters emerged in the market to enhance their performance of hemocompatibility especially for hydrophilic coating catheters. Unfortunately, to date, the hemocompatibility of hydrophilic coating still remains controversial due to the inherent complexity of the hemocompatibility test itself and lack of validated test methods. In this study, through determining the hemocompatibility performance for a micro-catheter with a typical hydrophilic pyrrolidone coating regarding haemolysis test, partial thromboplastin time (PTT), prothrombin time (PT) and thrombogenicity test in dogs, we have established a series of tentative hemocompatibility protocols for these tests. Hopefully, our study could not only provide some useful information for hemocompatibility evaluation on medical catheters with a hydrophilic coating but could also contribute to the development of neo-type hemocompatible medical devices for better clinical practice.

Strategy on biological evaluation for biodegradable/absorbable materials and medical devices.

During the last two decades, biodegradable/absorbable materials which have many benefits over conventional implants are being sought in clinical practices. However, to date, it still remains obscure for us to perform full physic-chemical characterization and biological risk assessment for these materials and related devices due to their complex design and coherent processing. In this review, based on the art of knowledge for biodegradable/absorbable materials and biological risk assessment, we demonstrated some promising strategies to establish and improve the current biological evaluation systems for these biodegradable/absorbable materials and related medical devices.

Evaluation of repeated exposure systemic toxicity test of PVC with new plasticizer on rats via dual parenteral routes.

Systemic toxicity caused by repeated exposure to both polar and nonpolar leachables of di(2-ethylhexyl)-1,2-cyclohexane plasticized polyvinyl chloride (PVC) was evaluated with dual routes of parenteral administration method on rats in the study. Experimental group and control group were designed by researchers. Tail intravenous injection with 0.9% sodium chloride injection extracts and intraperitoneal injection with corn oil extracts were conducted to the experimental rats while tail intravenous injection with 0.9% sodium chloride Injection and intraperitoneal injection with corn oil were conducted to the control rats. After 14 days, blood specimens were collected for clinical pathology (hematology and clinical chemistry) analysis. Selected organs were weighed and a histopathological examination was conducted. As a result, compared with the control animals, there were no toxicity-related changes on the parameters above. The results show that the rats do not show obvious systemic toxicity reaction caused by repeated exposure with dual routes of parenteral administration method on rats after administration with both polar and nonpolar exacts of di(2-ethylhexyl)-1,2-cyclohexane plasticized PVC simultaneously up for 14 days.

TLR4 Promotes Breast Cancer Metastasis via Akt/GSK3ß/ß-Catenin Pathway upon LPS Stimulation.

Bacteria/virus-induced chronic inflammation is involved in both tumor initiation and tumor progression. Toll-like receptor 4 (TLR4) has been implicated in the development of several types of cancer. In this study, we explored the impact of TLR4 activation by lipopolysaccharide (LPS) on breast cancer metastasis and associated signaling molecules. We first examined TLR4 expression levels in breast tissue using a human breast tissue microarray and breast cell lines. We then studied the role of TLR4 activation by LPS stimulation in breast cancer metastasis using both in vitro and in vivo models. Finally, we investigated signaling molecules involved in the process using Western blotting and fluorescent immunohistochemistry staining. The results showed that TLR4 expression levels increased in breast cancer tissue compared to normal breast tissue. In addition, our results also showed that TLR4 pathway activation by LPS stimulation in MCF7 and MDA-MB-231 breast cancer cells caused the following actions: (1) promotes migration of breast cancer cells, (2) triggers the ß-catenin signaling pathway via PI3K/Akt/GSK3ß, and (3) promotes transcription of downstream ß-catenin target genes leading to breast cancer metastasis. This study substantiates and further extends the relationship between TLR4 activation by LPS and breast cancer using both in vitro and in vivo models. The results suggest that the Akt/GSK3ß/ß-catenin signal transduction pathway may serve as a viable clinical treatment target in breast cancer. Anat Rec, 300:1219-1229, 2017. © 2017 Wiley Periodicals, Inc.