Polystyrene microplastics induce pulmonary fibrosis by promoting alveolar epithelial cell ferroptosis through cGAS/STING signaling.

Polystyrene microplastics (PS-MPs) are new types of environmental pollutant that have garnered significant attention in recent years since they were found to cause damage to the human respiratory system when they are inhaled. The pulmonary fibrosis is one of the serious consequences of PS-MPs inhalation. However, the impact and underlying mechanisms of PS-MPs on pulmonary fibrosis are not clear. In this study, we studied the potential lung toxicity and PS-MPs-developed pulmonary fibrosis by long-term intranasal inhalation of PS-MPs. The results showed that after exposing to the PS-MPs, the lungs of model mouse had different levels of damage and fibrosis. Meanwhile, exposing to the PS-MPs resulted in a markedly decrease in glutathione (GSH), an increase in malondialdehyde (MDA), and iron overload in the lung tissue of mice and alveolar epithelial cells (AECs). These findings suggested the occurrence of PS-MP-induced ferroptosis. Inhibitor of ferroptosis (Fer-1) had alleviated the PS-MPs-induced ferroptosis. Mechanically, PS-MPs triggered cell ferroptosis and promoted the development of pulmonary fibrosis via activating the cGAS/STING signaling pathway. Inhibition of cGAS/STING with G150/H151 attenuated pulmonary fibrosis after PS-MPs exposure. Together, these data provided novel mechanistic insights of PS-MPs-induced pulmonary fibrosis and a potential therapeutic paradigm.

Characteristics of PLGA-gelatin complex as potential artificial nerve scaffold.

The segmentation lesion of peripheral nerve will seriously impair the motion and sensation of the patients, and the satisfactory recovery of segmented peripheral nerve by autograft or allograft is still a great challenge posing to the neurosurgery. Apart from autograft for nerve repair, different allograft has been studying. In this study, a scaffold fabricated with polylactic acid-co-glycolic acid (PLGA) copolymer and gelatin was evaluated to be a potential artificial nerve scaffold in vitro. The effect of different mass ratio between PLGA and gelatin upon the characteristics of PLGA-gelatin scaffolds such as microstructure, mechanical property, degradation behavior in PBS, cell adhesion property were investigated. The results showed the homogeneity and mechanical property of the scaffolds became poor with the increase of gelatin, and the rate of max water-uptake and the mass loss of scaffolds increases with the increase of gelatin, and the cells could adhere to the scaffolds. Those indicated the scaffolds fabricated by the PLGA-gelatin complex had excellent biocompatibility, suitable mechanical property and sustained-release characteristics, which would meet the requirements for artificial nerve scaffold.

[Review of heparin immobilization technique].

Immobilization of heparin onto the surfaces of biomaterials is an effective approach for improving their anticoagulant properties and biocompatibility. In this article are reviewed the relevant principle, experimental researches and applications. Finally, a prospect for heparin immobilization is made as well.

[Experimental study on a novel affinity adsorbent for removal of endotoxin in plasma].

In this paper, the adsorbent properties of Polymyxin B immobilized polystyrene microbeads to remove endotoxin from plasma were studied and the factors that affected the absorption of endotoxin were discussed. The rat models of endotoxemia were established, which were used in hemoperfusion. The experiment results indicated that the novel affinity adsorbent could remove endotoxin from plasma effectively. Moreover, the results also showed that Polymyxin B immobilized polystyrene microbeads was a fine biomaterial of hemoperfusion as well as exhibited a satisfactory blood compatibility.

Adhesion strength of human tenocytes to extracellular matrix component-modified poly(DL-lactide-co-glycolide) substrates.

We report a direct measurement of the adhesion strength of human embryonic tenocytes (HETCs) and transformed human embryonic tenocytes (THETCs) to fibronectin (FN)- and type I collagen (CNI)- modified poly(DL-lactide-co-glycolide) (PLGA) substrates with a micropipette aspiration technique. PLGA substrates were first coated with poly-D-lysine (PDL), and then with various concentrations (1 microg/ml, 2 microg/ml, 5 microg/ml, and 10 microg/ml) of FN and CNI in serum-free F12 media. Anti-FN and Anti-CNI antibodies were used to inhibit attachment of tenocytes to FN- and CNI- modified substrates in a dilution range of 1:5000-1:500 and 1:1500-1:250, respectively. The substrates were employed for incubation of HETCs and THETCs for 30 min at 37 degrees C before the adhesion strength measurements. We found that the adhesion strengths showed a strong dependence on the seeding time and FN or CNI concentrations. Anti-FN and Anti-CNI antibodies significantly compromised adhesion of HETCs and THETCs to the corresponding modified substrates (P < 0.05). These findings show that FN- or CNI-modified polymer substrates offer significant advantages for tissue engineering tendon scaffolds concerning tenocyte adhesion. In addition, HETCs and THETCs bear similar biological behaviors in terms of adhesion, indicating the possibility of using THETCs in place of HETCs in tissue engineering construction of human tendons.

A novel polydimethylsiloxane microfluidic viscometer fabricated using microwire-molding.

We present a new economical microfluidic viscometer to measure the viscosity of biological fluids, using sample volumes of less than 200 µl. It is fabricated using a microwire-molding technique, making it easier and cheaper to produce than existing viscometers. The viscometer is based on laminar flow inside a polydimethylsiloxane microchip. The velocity of the sample flow inside the capillary was monitored with a camera, and the movement of the liquid column was determined by a Matlab video-processing program. The device was calibrated using deionized water, which is a Newtonian fluid, at 20 °C. The viscometer provides accurate measurements of viscosity for values as small as 0.69 mPa s. The viscosity of water at different temperatures was measured, showing more than 98% agreement with the values provided by the National Institute of Standards and Technology. Various samples including a series of glycerol solutions, phosphate-buffered saline, alcohol, and cell media were also tested, and the measured viscosities were compared with those from a traditional glass capillary viscometer. The results show good agreement between the two methods, with an average relative error of less than 1%. Furthermore, the viscosities of several cell suspensions were measured, showing a relative standard deviation of less than 1.5%. The microchip viscometer is economical and is shown to be accurate, which is very important for the simulation and control of lab-on-a-chip experiments.

Adhesive properties of hepatoma cells to collagen IV coated surfaces.

OBJECTIVES: To quantitatively study the adhesive properties of hepatoma cells to collagen IV coated artificial basement membrane and to investigate the relevance of cell adhesive forces to the concentration of collagen IV. METHODS: Synchronous G1 and S phase cells were achieved using thymine-2-desoxyriboside and cochicine sequential blockage method and double thymine-2-desoxyriboside blockage method respectively. The adhesive forces of hepatoma cells were investigated by micropipette aspiration technique. RESULTS: The adhesive forces of hepatoma cells to artificial basement membrane were (107.78+/-65.44)x10(-10)N, (182.60+/-107.88)x10(-10)N, (298.91+/-144.13)x10(-10)N when the concentration of the membrane coated by 1, 2, 5 microg/ml collagen IV respectively (P<0.001). The adhesive forces of G1 and S phases hepatoma cells to artificial basement membrane were (275.86+/-232.80)x10(-10)N and (161.16+/-120.40)x10(-10)N respectively when the concentration of the membrane coated by 5 microg/ml collagen IV (P<0.001). CONCLUSIONS: The adhesive forces of hepatoma cells to artificial basement membrane in direct proportion to the concentration of collagen IV suggests that the increase of basement membrane might be conducive to the chemotactic motion and adhesiveness of tumor cells. G1 phase cells are more capable of adhering to basement membrane than S phase cells. Hepatoma cells, especially G1 phase cells, may survive in blood circulation, and sequest and adhere in microcirculation, and get through basement membrane for remote metastasis.

[The preparation and properties of Modified silk fibroin membranes by chitosan].

The Modified silk fibroin membranes were prepared by mixing the aqueous solutions of both silk fibroin and chitosan with the use of oxidized glucose aldehyde as a crosslinking agent. It was characterized by FTIR, DSC, measurements of membrane-potential and mechanical properties, the water swelling ratios and permeability coefficient for model drug 5-Fu in the different pH buffer solutions. It was shown that there were some strong hydrogen bond interaction and good compatibility between silk fibroin and chitosan molecules in the modified silk fibroin films. The isoelectric point of modified fibroin film was about pH 5.35, but that of natural fibroin film was around pH 4.5. It was also found that the mechanical properties of modified fibroin films were much better than those of fibroin itself. Its tensile strength and breaking elongation were greatly enhanced with the increase of chitosan content and their maximum values were as high as 71.4-72.7 MPa and 2.96%-3.82% respectively, at the composition of 40 wt%-60 wt% chitosan. Its coefficient of permeability decreased firstly and then increased slowly with the change of the pH value of solutions from pH 5 to pH 9, and the minimum coefficient of permeability was observed when pH=7.

[Characteristics of tenocyte adhesion to biologically-modified surface of polymer].

In this study we examined the in vitro characteristics of tenocyte adhesion to biologically-modified surface of polymer. Polylactic-co-glycolic acid (PLGA) 85/15 films were prepared by a solvent-casting technique. Each film was adhered onto the bottom of a chamber. The film was precoated with poly-D-lysine (PDL), and then coated with serum-free F12 medium containing various concentrations of fibronectin (FN), type I collagen (CN I), and insulin-like growth factor1 (IGF-1). The monoclonal antibodies (to FN and to CN I) with various dilutions were used to inhibit attachment of tenocytes to surface precoated with FN or CN I. Human embryonic tendon cells (HETCs) and transformed human embryonic tendon cells (THETCs) were used as the seeding cells. The system used for the measurement of adhesion force was the micropipette aspiration experiment system. The micropipette was manipulated to aspirate a small portion of the tenocyte body by using a small aspiration pressure. Then the pipette was pulled away from the adhesion area by micromanipulation. The minimum force required to detach the tenocyte from the substrate was defined as the adhesion force. The results showed that modification of FN or CN I by precoating significantly enhanced attachment of tenocytes to surface of polymer (P < 0.05). As antibodies to FN or CN I were added to a polymer film precoated with FN or CN I, the adhesion force decreased significantly (P < 0.05). We concluded that the specific adhesion forces of tenocytes to extracellular matrix adhesion proteins (FN and CN I) had coordinated action and showed good dependence on their precoating concentrations, and were inhibited by the antibodies to these adhesion proteins. Films precoated with IGF-1 strongly accelerated the adhesion of tenocytes to polymer. These results indicate that the specific adhesion of tenocytes to polymer can be promoted by coating extracellular matrix adhesive proteins and insulin-like growth factor1. It is of great importance to construct tissue-engineered tendon.

[Analysis of an acellular pigskin based nerve scaffold].

A scaffold fabricated with lysine/nerve growth factor (NGF)/poly (lactic acid coglycolic acid) copolymer (PLGA) and acellular pigskin was evaluated in vitro as a potential artificial nerve scaffold. Properties of the scaffold such as microstructure, mechanical property, degradation behavior in PBS and water, Schwann cell adhesion property, and release of NGF were investigated. Results showed PLGA had permeated into the porous structure of acellular pigskin; its breaking strength was 8.308 MPa, breaking extensibility was 38.98%, elastic modulus was 97.27 MPa. The porosities of the scaffold ranged from 68.3% to 81.2% with densities from 0.62 g/cm3 to 0.68 g/cm3. At 4 weeks of degradation in vitro, maximum mass loss ratio was 43.3%. The release of NGF could still be detected on the 30th day, and its accumulative release rate was 38%. Lysine added into the scaffold neutralized the acidoid preventing degradation of PLGA to maintain a solution pH value. Schwann cells had grown across the scaffold after co-cultivation for 15 days. These in vitro properties of the pigskin based composite might indicate its potentiality to be an artificial nerve scaffold.

Fabrication of a PLGA-collagen peripheral nerve scaffold and investigation of its sustained release property in vitro.

This study deals with the fabrication of a peripheral nerve scaffold prepared with poly (lactic acid-co-glycolic acid) [PLGA] and acellularized pigskin collagen micro particles and the investigation of its sustained release property in vitro. We took bovine serum albumin [BSA] as model drug to investigate the sustained-release property of the scaffold in vitro. The results showed the scaffold could release BSA steadily with a rate of 6.6 ng/d (r=0.994) or so. In a 1-month test period, the accumulative release ratio of BSA from the scaffold was up to 43%, and the shape of the scaffold was still originally well kept. In addition, the scaffold outcome non-immunogenicity, good cell adhesion and biodegradability. The results indicated a scaffold constructed by this technique would be a potential implanting support with prolonged sustained release function, such as for the use of nerve scaffold.

Preparation of heparin-immobilized PVA and its adsorption for low-density lipoprotein from hyperlipemia plasma.

In this study, heparin was covalently coupled by glutaraldehyde to Poly(vinyl alcohol) [PVA] in solid-liquid two-phase reaction system by two-step synthesis method to prepare a LDL-selective adsorbent. The parameters (the material ratio, reaction time and dosage of catalyzer) were investigated to evaluate their effect upon the immobilized amount of heparin onto the surface of PVA, IR was used to verify the covalent immobilization result and the heparin-modified PVA was also undergone the evaluation of its adsorption capability for low-density lipoprotein from hyperlipemia plasma, and its hemocompatibility was preliminarily evaluated by platelet adhesion test. Results showed: (1) under optimized reaction conditions the highest immobilization amount of heparin onto PVA surface within the experiments of this study has been obtained; (2) the optimized reaction conditions were: (i) at the refluxing temperature 78 degrees C; (ii) the material ratio of "PVA(g): 50% glutaraldehyde (ml)" was about "1:3"; (iii) the reaction time was about 5 h; and (iv) the amount of catalyzer (concentrated HCL) was about 1% of the 50% glutaraldehyde; (3) within the experiments of this study the highest immobilization amount would be up to 25 microg heparin on the surface of per g PVA granules; (4) the heparin-modified PVA granules showed significant adsorption for LDL under faintly alkaline environment (pH=7.2-9.5) ; (5) The result of platelet adhesion test showed no platelet adhered to its surface. Therefore, immobilization of heparin onto the surface of a support is one approach to prepare a kind of LDL adsorbent for blood purification.

In vitro characteristics of poly(lactic-co-glycolic acid) microspheres incorporating gelatin particles loading basic fibroblast growth factor.

AIM: To construct a sustained drug release system for basic fibroblast growth factor (bFGF). With this special system, bFGF can be used to repair an injured peripheral nerve, injured spinal cord, or as a carrier for other drugs that need to be released over a long time. METHODS: Microsphere composite was prepared by encapsulating bFGF into gelatin particles with poly(lactic-co-glycolic acid) (PLGA) as its outer-coating. The encapsulation was conducted by a phase separation method. RESULTS: The average diameter of the gelatin particle-PLGA microsphere composite was 5-18 mum, and bFGF-loading efficiency was up to 80.5%. The bFGF releasing experiment indicated that this new composite system could release bFGF continuously and protect bFGF from denaturation. CONCLUSION: A modified approach was successfully employed to develop a biodegradable system for sustained release of the drug of bFGF in vitro.