Objective To establish a finite element model of cell perfusion culture, and study the effect of different perfusion speeds on the movement of suspended cells. Methods The two-dimensional (2D) model of cell and microchannels was established using COMSOL Multiphysics and meshed. Three groups were established according to the perfusion speed, namely, u0=0.196 mm/s, u1=0.117 mm/s, u2=0.04 mm/s. The fluid-structure interaction module was used for calculation. Results The flow field distribution in the microchannel was relatively uniform. During the equal period of time, the ratio of cell suspension perfusion speed was u0∶u1∶u2=5∶3∶1, and the ratio of cell displacement in the microchannel was D0∶D1∶D2=4.1∶ 2.9∶1. When the speed was proportional, the displacement of cells also roughly followed the corresponding proportional change. With the increase of perfusion speed, stress concentration in cells during movement would occur. The stress and fluid shear force (FSS) of cells during movement were within the safe value range, and cell destruction would not occur. Conclusions The suspended cells can enter into the microchannel without injury at a certain perfusion speed. Perfusion techniques can be used in cell implantation of in vitro tissue engineering products.

Objective To observe the analgesic effects of mild moxibustion on primary dysmenorrhea(PD)rats with cold and dampness stagnation syndrome and its effect on BDNF/TrkB signaling pathway in hypothalamus;To explore its mechanism for the treatment of PD.Methods A total of 32 Wistar non-pregnant female rats were randomly divided into blank group,model group,Western medicine group and mild moxibustion group,with 8 rats in each group.Except for the blank group,the other groups received estradiol benzoate intraperitoneal injection combined with ice bath treatment + oxytocin intraperitoneal injection to establish PD with cold and dampness stagnation syndrome model.The mild moxibustion group received treatment at"Shenque"and"Guanyuan"from the eighth day of modeling for 10 min,and the Western medicine group was given ibuprofen solution intragastically for 4 days.The latency period of rats twisting was observed and the twisting score was calculated,Western blot and PCR were used to detect the expressions of c-fos,BDNF,TrkB protein and mRNA in hypothalamic tissue.Results Compared with the blank group,the model group showed a shortened latency period and an increased twisting score(P<0.01),the expressions of c-fos,BDNF,TrkB protein and mRNA in hypothalamic tissue increased(P<0.01,P<0.05).Compared with the model group,the mild moxibustion group had a longer latency period and lower twisting score(P<0.01),while the expressions of c-fos,BDNF,TrkB protein and mRNA in hypothalamic tissue increased(P<0.01,P<0.05).Conclusion Mild moxibustion may effectively improve the pain state of PD rats with cold and dampness stagnation syndrome.This mechanism may be related to downregulating c-fos expression,inhibiting BDNF/TrkB signaling pathway activation,thereby inhibiting pain signal transmission,regulating pain occurrence and maintenance.

At present, acellular matrix is an effective replacement material for the treatment of skin damage, but there are few systematic evaluation studies on its performance. The experimental group of this study used two decellularization methods to prepare the matrix: one was the acellular matrix which sterilized with peracetic acid first (0.2% PAA/4% ethanol solution) and then treated with hypertonic saline (group A), the other was 0.05% trypsin/EDTA decellularization after γ irradiation (group B); and the control group was soaked in PBS (Group C). Then physical properties and chemical composition of the three groups were detected. Hematoxylin eosin (HE) staining showed that the acellular effect of group B was good. The porosity of group A and B were both above 84.9%. In group A, the compressive modulus of elasticity was (9.94 ± 3.81) MPa, and the compressive modulus of elasticity was (12.59 ± 5.50) MPa in group B. There was no significant difference between group A or B and group C. The total content of collagen in acellular matrix of group A and B was significantly lower than that of group C (1. 662 ± 0.229) mg/g, but there was no significant difference in the ratio of collagen Ⅰ/Ⅲ between group B and group C. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that there was no significant difference in microstructure. Qualitative detection of fibronectin and elastin in each group was basically consistent with that in group C. Therefore, acellular matrix of group B had better performance as scaffold material. The experimental results show that the acellular matrix prepared by γ-ray sterilization and decellularization of 0.05% Trypsin enzyme/EDTA could be used for the construction of tissue-engineered skin. It could also provide reference for the preparation and mounting of heterogeneous dermal acellular matrix. It was also could be used for electrostatic spinning or three-dimensional printed tissue engineered skin scaffold which could provide physical and chemical parameters for it.
Acellular Dermis ; Cells, Cultured ; Extracellular Matrix ; Porosity ; Tissue Engineering ; Tissue Scaffolds