A wound dressing made of nanosilver and bacterial cellulose / 中国组织工程研究

BACKGROUND:In recent years, bacterial celulose modified by nano-composite technology has been endowed with new properties. OBJECTIVE:To review the combination of bacterial celulose and nanosilver to prepare wound dressing. METHODS: A computer-online search was performed in PubMed (2013-01/2015-04) and CNKI (2007-01/2015-04) databases to retrieve studies on bacterial celulose, nanosilver and their compound method and application using the key words of “bacterial celulose, nano-silver” in English and Chinese, respectively. RESULTS AND CONCLUSION:Bacterial celulose/nano-silver compound can be prepared by three methods: solution impregnation, in situ composite and biocomposite. Solution impregnation method can lower the concentration of nanosilver ions in the fiber matrix to highly control the release of silver ions, but the genetic toxicity and biocompatibility are unclear.In situcomposite method can reduce the damage to the mesh structure of celulose on which silver ions can be bonded firmly to reduce the toxic damage to cels, but the reducing agent used has a higher toxicity, which is difficult to remove. Biocomposite method cannot produce toxic substance, which is friendly to the environment, and the synthetic biomaterials have less harm to the human body and can be controled highly.

In vitro evaluation of the function of sheet biomaterials in platelet activation / 生物医学工程学杂志

In China, the evaluation of hemocompatibility of biomaterials is limited to hemolysis, coagulation time,and the number and morphology of platelets adhered on biomaterials. The present research, however, is aimed to establish a method for evaluating the function of sheet biomaterials in platelet activation. Platelet activation caused by glass, polyvinyl chloride or polymethylvinylsiloxane sheets was evaluated by measuring alpha-granule membrane protein (GMP-140) in platelet poor plasma, using a reasonable blood-material contact model vibrating at different speed. The result showed that the difference in platelet activation was not significantly different among the three above-mentioned materials at 140r/m or 200r/m. However, when it comes to 230r/m, significant difference was observed among these three groups, with glass > polyvinyl chloride > polymethylvinylsiloxane. But the order was reversed at 270r/m, which may be due to the different interfacial tension of different materials. Therefore, the method is suitable to evaluate platelet activation caused by sheet biomaterials, but an appropriate vibrating speed should be chosen. The interfacial tension plays an important role in the model and should be considered for results assessment.

Research progress in mechanisms of biocompatibility / 国际生物医学工程杂志

The interaction of biomaterials and tissues has been the focus of biomaterial science for many years and formed the foundation of the subject of biocompatibility. The research about biomaterials provides better basis for biomedical devices by the understanding of biocompatibility phenomena. In this paper, over 50 years of experience with such devices is analysed and it is shown that, in the vast majority of circumstances, the sole requirement for biocompatibility in a medical device intended for long-term contact with the tissues of the human body is that no harm should be brought to those tissues. Only a few bio-active biomaterials has been applied successfully in clinics. This artical gives a review on the application of biomaterials in tissue engineering,sophisticated cells, drug and gene delivery systems and in biotechnology. Interactions between biomaterials and tissue components is discussed as well.

Cytocompatibility of nano-hydroxyapatite/bacterial cellulose nanocomposites and its residues / 中国组织工程研究

BACKGROUND: The nano-hydroxyapatite/bacterial cellulose (nHAP/BC) nanocomposites has a good prospect of application in bone tissue engineering, and the bone tissue engineered materials and its degradation products Should have excellent compatibility. This study further assessed DAN synthesis cycle using flow cytometry on the basis of evaluating cell compatibility by metabolic 3-(4, 5-dim ethylthiazo 1-2-y 1) -2, 5-Dipheny 1-2H-tetrazolium (MTT) assay. OBJECTIVE: To evaluate the cytocompatibility of a new-pattern nHAP/BC nanocomposites and its residues. METHODS: Effects of nHAP/BC nanocomposites and its residues on morphclogicel changes in osteoblasts were observed using in vitro cell culture method. Effects of nHAP/BC nanocomposites and its residues on osteoblast growth and prclifera'don were evaluated by MTT assay. Cell cycle phase changes were detected using flow cytometry to evaluate matsdal effects on cell proliferation on molecular levels. RESULTS AND CONCLUSION: The nHAP/BC nanocomposites and its residues had neither remarkable effects on cell morphology, nor significant inhibition on osteoblast growth and proliferation. Test of MTT cytotoxicity showed that the average cell proliferation rate was over 80% after treated with the material and its residues, with the cytotoxity grade of 1 (non-toxic). Flow cytometry indicated that the rate of G_0/G_1 was reduced, and the rates of S, G2/M were increased, and the synthesis of DNA was increased, the cellular growth and repair in osteoblasts was accelerated. These indicated that nHAP/BC nanocomposites have good cytocompatibility, and it will be safe and prospected scaffolds in bone tissue engineering.

The kinetics of in vitro lysozyme deposition on rigid gas-permeable contact lens for a short period / 中国组织工程研究

BACKGROUND: The contact lenses were easily contaminated by adsorbing components from the tear film, particularly protein after wearing for a period of time. Lysozyme adsorption dynamics of fluorosilicone acrylate contact lenses has been studied in order to further improve data of protein adsorption, reduce adsorbing amount of surface protein, and prevent surface contamination of contact lenses.OBJECTIVE: To investigate the adsorption dynamics of fluorosilicone acrylate contact lenses to lysozyme in vitro. METHODS: A stock solution of lysozyme was prepared in Hanks balanced salt solution (2.0 g/L, solution Ⅰ) and different trifluoroacetic acid (TFA) concentrations were prepared. Recovery experiment, the contact lenses were placed in shaking incubator at 37 ℃ for varying time intervals. After incubation there was a single rinsing in Hanks balanced salt solution. Contact lenses in control group were placed in diluted water, and contact lenses in the other group were placed in different concentrations of TFA. For deposition, FSA contact lenses in experimental group were placed in shaking incubator at 37 ℃ for varying time intervals. After incubation there was a single rinsing in Hanks balanced salt solution. Then FSA contact lenses were immersed in 0.2% TFA solution. The amount of lysozyme was assayed with BCA method.RESULTS AND CONCLUSION: Lysozyme which attached to fluorosilicone acrylate contact lenses could be resolved by TFA, and the recovery was influenced by the immersed time and the concentration of TFA. The optimal time was 1 hour, and the optimum concentration was 0.2%. The adsorption dynamics of lysozyme on FSA contact lenses was a second-phased process, i.e., lysozyme adsorption increased rapidly during 10 minutes-1 hour, reached a plateau at 1 hour, stably adsorbed during 1-24 hours, and reached a saturation of 0.349 mg/cm~2. The recovery of lysozyme was lower at 10 and 30 minutes, but reached 90%-100% while the time of incubation was between 40 minutes and 24 hours.

In vitro evaluation of platelet activation by tubular biomaterials / 中国组织工程研究

BACKGROUND: In according to ISO-10993-4 and GB/T 16886.4, the in vitro hemo-compatibility evaluation on biomaterieisincludes thrombosis, coagulation factors, platelets and platelet functions, hematology and complement system. However, in thecase of China, the in vitro hemo-compatibility evaluations were performed only thrombosis, coagulation factors and plateletattachment, the investigation on evaluation of platelet and complement activations is less reported.OBJECTIVE: To evaluate the effect of polyethylene, polyvinyl chloride and polymethylvinylsiloxane tubes on platelet activation,and establish a useful method to evaluate the effect of tubular materials on platelet activation.METHODS: Tubes of polyethylene, poiyvinyl chlorid and silastic were established by 3.7 mm inner diameter, 3.5 mm externaldiameter, and 35 cm length, respectively. 1 mL blood was injected into the tube of polyethylene, polyvinyl chlorid and silasUc,respectively. The tubes were connected using a two-way tube, shaken at 140 r/min by 30° sloping for 3.5 hours at 37 ℃.Radiolmmunoassay was employed to detect α-granules protein level of platelet poor plasma, while flow cytometry was used todetect the percentage of positive plateiet of o-granules protein and that of activated gp Ⅱb/Ⅲa composite.RESULTS AND CONCLUSION: Radiolmmunoassay showed that o-granules protein level of plateiet poor plasma in thepolyethylene and polyvinyl chlorid tubes was significantly greater than that in the silastic tube (P < 0.05). There were no significantdifferences in o-granules protein between polyethylene and polyvinyl chlorid (P > 0.05). Flow cytometry indicated that percentageof positive platelet of o-granules protein in the polyethylene and polyvinyl chlorid tubes was significantly greater than that in thesilastic tube (P < 0.05); the percentage in the polyethylene tube was significantly greater than that in the polyvinyl chlorid tube (P <0.05). There was no significant differences in the percentage of positive plateiet of activated gp IIb/IIIa composite between thethree materials (P > 0.05). A useful blood-material contact model was established, and it was considered that o-granules protein isan available parameter for evaluating platelet activation. The percentage of positive platelet of o-granules protein determined byflow cytometry was a more sensitive parameter for evaluating platelet activation.

Nanosilver subchronic toxicity and silver distribution in different rat tissues / 中国组织工程研究

BACKGROUND: It has been reported that nanosilver-containing biomaterials produce bad biological effects after they directly contact with or are implanted into human body.OBJECTIVE: To investigate whether nanosilver yields potential adverse biological effects on human body and to evaluate its bioiogical safety.DESIGN, TIME AND SETTING: An animal experiment observation was performed at the Medical Device Center of National Institute for the Control of Pharmaceutical and Biological Products from June 2005 to August 2006.MATERIALS: Nanosilver particles and microsilver particles were purchased from Sigma Company, USA.METHODS: Thirty rats were randomly divided into 3 groups, with 5 male and 5 female rats per group: nanosilver, microsilver, and blank control. Nanosilver and microsilver particles were respectively and subcutaneously implanted for subchronic toxicity test.The nanosilver and microsilver groups were given 0.33 g/kg nanosilver and microsilver, respectively. Rats from the blank control group received identical procedure, with the exception of drug application. Four rats were selected from each group for determination of silver content in serum and some organs by plasma mass spectrometry.MAIN OUTCOME MEASURES: serum biochemical indices, organ coefficient, and silver content.RESULTS: There was significant difference in individual organ coefficient between each drug application group and blank control group. But no significant difference in absolute mass was found between each drug application and the blank control group.These findings suggested no clinical significance of organ coefficient. Other organ coefficients were in the normal range, and there was no significant difference between each drug application group and the blank control group. Patho-histological changes related to toxicity were not found. Rats from the nanosilver group did not show toxic reaction.CONCLUSION: Nanosilver produces potential adverse biological effects after implanted into human body.

Detection of unknown residual solvents of sodium hyaluronate product / 中国组织工程研究

BACKGROUND: A mass of unknown remains are founded in sodium hyaluronate product when it was tested for quality control. OBJECTIVE: To qualify and quantify unknown residual solvents of sodium hyaluronate product and determine hazardsaccording to standard toxicological data. DESIGN, TIME AND SETTING: A quality and quantity study with combined gas chromatography mass spectrometry was performed at National Institute for the Control of Pharmaceutical and Biological Products from May to June 2007.MATERIALS: Experimental samples were spot-checked, and purified water was also used.METHODS: The samples were qualified and quantified using combined gas chromatography mass spectrometry.MAIN OUTCOME MEASURES: Methanol, xylene and ethyl benzene were qualified and quantified.RESULTS: Combined gas chromatography mass spectrometry demonstrated that residual solvents in the sodium hyaluronateproducts were methanol, xylene, and ethyl benzene. The quantization of methanol was 414.365 μg/mL, the quantization of o-xylene was 0.19 μg/mL, and the quantization of ethyl benzene was 0.22 μg/mL. CONCLUSION: Methanol, xylene, and ethyl benzene were firstly identified as residual solvents in sodium hyaluronate products. Besides, we discussed methods of qualifying and quantifying these three residual solvents.

Study and evaluation on hemocompatibility of biomaterials / 生物医学工程学杂志

Hemocompatibility is an important component of biocompatibility; it reflects the degree of interaction between material and blood. Hemocompatibility is multifaceted, so that the material's impact on the blood and the underlying mechanism are very complicated. This article presents a review of researches probing the impact of material on blood via contact activation and plasma protein adsorption; via the platelet activated and the formation of thrombin; via the complement system activated and the activation of leukocytes as well as other mechanisms of hemolysis. The current methods for evaluation and the future trend of development are also introduced.

Immunological evaluation into the bone allograft and selection of experimental animal model on im-munogenicity / 中华创伤骨科杂志

Objective To explore the effect of immunogenicity of freeze-dried bone allograft on different in vitro experimental models. Methods The lymphocytes were obtained respectively from 10 healthy young human volunteers, 10 Balb/c and 10 C57 mice and 10 New Zealand rabbits. The experiment was carried out in 6 groups: positive control group (PHA/ConA+lymphocyte), negative control group (Hydroxyapatite powder + lymphocyte), allogeneic bone group A (Freeze-dried bone powder 2. 0 g/L + lym-phocyte), allogeneic bone group B (Freeze-dried bone powder 1.0 g/L + lymphocyte), allogeneic bone group C (Freeze-dried bone powder 0.5 g/L + lymphocyte), and negative control group (culture solution + lym-phocyte). Lymphocyte transformation test (Alamarblue) was conducted to culture the 6 kinds of experimental materials in vitro. After 72 hours, samples were scanned with ELISA muhiscan at wave lengths 570 nm and 600 nm to fetal the light absorption value. Pearson analyses were performed 10 determine the relationships a-mong the 3 animals and 1 human groups and find out which animal would be highly correlated to human. Results In the human and Balb/c mice lymphocyte transformation tests, there was no significant difference (P > 0.05) between allogeneic bone groups A, B, C and negative control group (HA) ; but there was sig-nificant difference (P < 0.001) between allogeneic bone groups A, B, C and positive control group (PHA/ConA); there was no significant difference between the 3 allogeneic bone groups (P > 0.05). There was no significant difference among the 6 groups of C57 mice and New Zealand rabbits (P > 0.05). The coefficient r between Balb/c mice and human groups was 0.959, P = 0.003, showing a highly positive correlation. The coefficient r between C57 mice and human groups was 0.527, P = 0.283, while the coefficient r between New Zealand rabbits and human groups was 0.866, P =0.026. Conclusions The immunogenicity of freeze-dried bone powder in this experiment may not be sufficient enough to induce significanrt immunologic response. Balb/c mice may be preferable for immunogenicity related experiments.

A long term accelerating corrosion fatigue texting of coronary stents in vitro / 生物医学工程学杂志

According to the related standards, an in vitro corrosion fatigue testing of coronary stents was designed. The stents were fixed in the latex tubes, which were full of 0.9% saline solution, and radial stress was produced for simulating natural vessel. The accelerated fatigue test was performed with 4 x 10(8) cycles at a frequency of 60 Hz, which was equal to 10 years in vivo implantation. Twelve coronary stents made from stainless steel were adopted in the experiment. The bulk structure and surface morphology before and after testing were analysed by scanning electron microscopy. The structure damage and surface change caused by corrosion fatigue were identified and the probable reasons were proposed.

Status of biological evaluation on silver nanoparticles / 生物医学工程学杂志

Silver nanoparticles have been widely used in medicinal and biological fields. Their biological evaluation is an important researchful field. In this paper are summarized the status quo of nano-hydroxyapatite biological evaluation at home and abroad. Although silver nanoparticles showed good biological compatibility when they were tested by contrast to ISO 10993 standards, some reports have proved that many medical devices loaded with silver could release silver ions (Ag+) which could translocate in blood circulation and cumulate in some organs such as liver and kidney. It may induce hepatotoxicity or renal toxicity and may lead to death in some situation extremely exposed to a certain dose of Ag+. The dimension of silver nanoparticles is close to silver ions and some reports have proved that they could translocate in body, so it is suggested that silver nanoparticles should induce the same toxicity with silver ions. In addition, silver nanoparticles have shown cytotoxicity in some experiment in vitro. But the mechanisms of its cytotoxity are not clear; it may attribute to the silver ions that release from silver nanoparticles or to the silver nanoparticles that permeate through cell membrane. Hence, there are some potential anxieties for the biological safety of silver nanoparticles.

Effect of steam sterilization on poly(ether-ester)s copolymer and its vascular cell compatibility / 生物医学工程学杂志

The aim of this research was to evaluate the influence of steam sterilization on poly(ethylene glycol-terephthalate) and poly(butylene terephthalate) copolymer (PEGT/PBT) and its vascular cells compatibility, which was used as the scaffolds in vascular tissue engineering. Endothelial cells, smooth muscle cells and fibroblasts were cultured separately on the films after steam sterilization and after ultraviolet sterilization. These cells can grow well on the films after ultraviolet sterilization, while they can hardly adhere on steam sterilized films. Differential scanning calorimetry, static contact angle, X-ray photoelectron spectroscopy, surface carboxyl density quantity, H-nuclear magnetic resonance and scanning electronic microscope were employed to characterize the properties of poly(ether-esters) films before and after sterilization. These results showed that steam sterilization had little effect on the surface morphology and on the constitution of the copolymer, but the copolymer segments were redistributed during steam sterilization. The hydrophilic poly(ethylene glycol) (PEG) and the end carboxyl groups transferred from the bulk and enriched on the surface and the degree of crystallinity of hard segments increased slightly. Both the end carboxyl and PEG enriched on the surface can hinder the protein adhesion on the surface; so, lacking in receptor, the vascular cells cannot adhere on the films surfaces.

Evaluation of immunological toxicity of medical devices / 生物医学工程学杂志

There has been increasing attention over the past few years on the potential for the medical devices to cause changes in the immune systems, and it was necessary to provide guidance on how to address the adverse effects of medical devices on the immune system. Here we introduce the principles and methods for immunotoxicology testing of medical devices.

In-vitro evaluation of haemocompatibility of biomaterials / 生物医学工程学杂志

In-vitro test is usually conducted as a preliminary screening test in the evaluation of the haemocompatibility of biomaterials for its short-term consuming, convenience and less expense. The selection of appropriate model for blood-biomaterial interaction, the choice of sensitive and specific parameters, and the minimization of additional blood activation are most important in the in-vitro test. In addition, the time and the style of blood-biomaterial interaction, the choice of sensitive and specific parameters, and the minimization of additional blood activation are most important in the in-vitro test. In addition, the time and the style of blood-biomaterial interaction, the selection of primary reference materials and the shear rate should be considered. In recent years, though great progress has been made in the in-vitro evaluation of haemocompatibility of biomaterials, all these influencing factor should be standardized for more effective evaluation of the haemocompatibility of biomaterials.

Experimental studies on the biocompatibility and safety of six implantation prosthesis / 中华医学美学美容杂志

Objective To compare biocompatibility and safety of six implantation prosthesis. Methods Subcutaneous implantation of crosslinked sodium hyaluronate prosthesis (CSHP), silica gel prosthesis(SGP), non crosslinked sodium hyalurorate prosthesis (NCSHP), carboxy methycel prosthesis (CMCP), hydrophilic polyacrylamide gel prosthesis (HPAGP), injectable hydrophilic polyacrylamide gel (IHPAG) was performed in 12 beagle dogs.Local reaction of surrounding tissues of the transplants were observed with HE and Van Gieson stains after the transplantation at 14, 30 and 90 days, 6 months, and 1 and 2 years. Results The most serious reaction was observed in NCSHP, CMCP and HPAGP, moderate reaction in CSHP and SGP and mild reaction in IHPAG. Van Gieson staining showed that collagenous fibrous capsule around implanted prosthesis was formed from 30 days to 2 years .The component and arrangment of the capsule were different among the defferent prosthesis, but changed with time. Shrinkage of the capsules was found in NCSHP, CMCP and HPAGP, and contraction occurred two years later. The capsules formed by CSHP and SGP had no contraction after two year implantation. IHPAG capsule was still soft and elastic after 2 years. Conclusions SGP is one of the best material for breast enlargement with a good biocompatobility and soft capsule. IHPAG is a new filling material with mild inflammatory reaction and thinner and softer capsule. CSHP should be improved further because its molding effect is not gratified. Both the biocompatibility and molding effect of NCSHP, CMCP and HPAGP are not gratified and further modification is needed.