Study on Modification of Poplar Wood via Composite Impregnation with Silica Sol/Melamine-Glyoxal Resin.

In order to overcome the defects of fast-growing poplar wood, such as low strength and poor toughness, this paper introduces a method of modifying poplar wood via impregnation with silica sol/melamine-glyoxal (silica sol/MG) resin and explores its effects on the physical, mechanical, and thermal properties of poplar wood. It was found via scanning electron microscopy that the composite modifier covered and filled the cell lumen, cell interstitial space, and cell wall pores of poplar wood. Further, infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirmed that chemical cross-linking occurred between the silica sol/MG resin composite modifier and the internal groups of poplar wood and that the Si-O-Si flexible long chains introduced in the composite modifier formed a cross-linking network with poplar wood such as Si-O-Si and Si-O-C, which led to the improvement of the physical and mechanical properties and the enhancement of the thermal stability of poplar wood. The method provides a theoretical basis for the high-value utilization of fast-growing poplar wood.

Extensive germline genome engineering in pigs.

The clinical applicability of porcine xenotransplantation-a long-investigated alternative to the scarce availability of human organs for patients with organ failure-is limited by molecular incompatibilities between the immune systems of pigs and humans as well as by the risk of transmitting porcine endogenous retroviruses (PERVs). We recently showed the production of pigs with genomically inactivated PERVs. Here, using a combination of CRISPR-Cas9 and transposon technologies, we show that pigs with all PERVs inactivated can also be genetically engineered to eliminate three xenoantigens and to express nine human transgenes that enhance the pigs' immunological compatibility and blood-coagulation compatibility with humans. The engineered pigs exhibit normal physiology, fertility and germline transmission of the 13 genes and 42 alleles edited. Using in vitro assays, we show that cells from the engineered pigs are resistant to human humoral rejection, cell-mediated damage and pathogenesis associated with dysregulated coagulation. The extensive genome engineering of pigs for greater compatibility with the human immune system may eventually enable safe and effective porcine xenotransplantation.

Effects of Compressive Stress on Osteoclast Activation / 医用生物力学

Objective To establish the 3D hydrogel cell model and apply compressive stress with different intensities, frequencies and durations on osteoclasts, so as to observe the effect of compressive stress on osteoclast differentiation and investigate the appropriate compressive stress solution for inhibiting osteoclast differentiation. Methods M-CSF and RANKL were used to induce bone marrow mononuclear cells into osteoclasts. After the 3D cell-agarose mixture was seeded in compression culture plate, compressive stress was applied on osteoclasts with different intensities, frequencies and durations the next day. The cells in control group were not interfered. The cells were divided as following: G0 (control group), G1 (1%, 0.5 Hz, 4 h), G2 (2%, 0.5 Hz, 4 h), G3 (3%, 0.5 Hz, 4 h), G4 (1%, 1.0 Hz, 4 h), G5 (2%, 1.0 Hz, 4 h), G6 (3%, 1.0 Hz, 4 h). After the loading plan with the most effective intensity and frequency was calculated by statistical analysis, compressive stresses were applied on cells with different durations as following: D1(4 h), D2(8 h), D3(12 h), D4(16 h), and each group had two samples. Once compressive loading was finished, the total RNA extraction from cell-gel constructs were performed and Ctsk mRNA, NFATc1 mRNA, TRACP mRNA, M-CSF mRNA and RANK mRNA were measured by quantitative testing. Results RANK and TRACP mRNA expression significantly depended on intensities and frequencies of the compressive stress (P<0.01), and Ctsk mRNA significantly depended on intensities(P<0.01) while it differed notably with different frequencies (P<0.01). M-CSF mRNA expression with 8 h was much lower than that with 12 h (P<0.01) and 16 h (P<0.05). RANK mRNA expression with 8 h was lower than that with 12 h (P<0.05) and 16 h (P<0.01). In addition, Ctsk and NFATc1 mRNA expression with 16 h was higher than that with 4 h and 8 h (P<0.05). Conclusions In the 3D hydrogel model, 1% intensity, frequency of 0.5 Hz, cyclic compression intervention with 8 h can suppress the differentiation of osteoclasts. The research findings provide the theoretical basis for preventing osteoporosis and improving the peak bone mass by appropriate exercise.

3D Hydrogel Compression Model and Effect of Cyclic Compression on Osteoblast Differentiation / 中国生物工程杂志

Objective:3D hydrogel cell model was established,and cyclic compressive loading on MC3T3-E1 cell with different intensities,frequencies and durations was applied,in order to research the suitable solution about promoting the osteoblast differentiation with cyclic compression.Methods:Cyclic compressive loading on MC3T3-E1 cell was applied with different intensity,frequency and time.After compressive loading finished,the total RNA extraction from cell-gel constructs were performed and quantified ATF4,ALP,Runx2,Osteocalcin,RANKL and RANK mRNA.Results:RANKL and RANK mRNA expression significantly with different frequencies cyclic compressive loading (P ＜ 0.05),and ALP mRNA (P ＜ 0.05) and Runx2 mRNA (P ＜ 0.01) expression significantly with different intensities and frequencies cyclic compressive loading (P ＜ 0.05).Meanwhile,Runx2 mRNA expression with 4h significant higher than 12h (P ＜ 0.05),and RANKL mRNA expression with 4h significant lower than 12h (P ＜ 0.05).Conclusion:Determine the stress intensity and frequency,1％ intensity,frequency of 0.5 Hz,4 h of cyclic compression intervention could promote the growth of osteoblasts-like cells in the 3D hydrogel model.