Effect of cell mechanics on morphogenesis of MDCK lobular organoid / 中国组织工程研究

BACKGROUND:The development of tissues and organs in the body is a precise and autonomously regulated process,and the function of biomechanical factors at this macroscale is a basic scientific question worth exploring. OBJECTIVE:To investigate the roles of cell mechanics in morphogenesis of the lobular organoid of 3D Madin-Darby canine kidney(MDCK). METHODS:The formation of MDCK lobular organoid was visualized by fluorescence resonance energy transfer technology,and the influence of different cellular mechanical signals and extracellular matrix environment on lobular organoid formation and corresponding changes in extracellular regulated protein kinases(ERK)activity were examined. RESULTS AND CONCLUSION:(1)Inhibition of ERK signaling pathway can inhibit the growth of MDCK lobular organoid.(2)Inhibition of cell contractile force signals such as ROCK pathway and Myosin Ⅱ activity,reduced ERK activity and lobular organoid size.(3)Selective inhibition of calcium channels in plasma membrane and endoplasmic reticulum led to reduced ERK activity and lobular organoid growth.(4)By inhibiting the mechanically-sensitive receptor Piezo ion channel or integrin signal on the cell membrane,the lobular organoid became smaller or MDCK cells could not generate tissue morphology.(5)Extracellular matrix compositions affected the morphogenesis of lobular organoid.The addition of type I collagen in Matrigel changed the lobular organoid to elongated shape.(6)The results of this study preliminarily show that mechanical signals in the cells and extracellular matrix environment play an important role in culturing MDCK lobular organoid,and provides certain molecular mechanisms.

Palmitoylation in Regulating Fyn Kinase Activity Based on FRET Imaging / 医用生物力学

Objective To investigate the molecular mechanism of palmitoylation modification in regulating the activity of non-receptor tyrosine kinase Fyn. Methods The intracellular Fyn activity was detected by applying fluorescence resonance energy transfer (FRET) technology, and the mechanism was investigated by combining with Fyn palmitoylation deficiency and C-terminal Src kinase ( CSK ) plasmid co-expression. ResultsExperimental data showed that single loss of either of ( C3, C6) palmitoylation sites resulted in higher Fyn activity, and C6 seemed more significant. It is known that CSK membrane translocation occurred after activation. FRET assay confirmed that CSK could down-regulate the activity of Fyn in cells, but could not effectively regulate the activity of Fyn(GSS) with the loss of palmitoylation sites. Conclusions The results in this study support the hypothesis on Fyn regulation by spatial localization, namely, non-palmitoylated Fyn (GSS) is less effective in the inhibitory regulation by CSK on cell membrane, thus promoting constitutive high activity expression

Biomechanical Issues of Mechanical Ventilation in Covid-19 Therapy / 医用生物力学

The critically ill coronavirus disease 2019 (Covid-19) patients usually present acute respiratory distress syndrome (ARDS), or even acute respiratory failure, and require mechanical ventilation (MV) to provide support for breathing. However, clinical studies have found an extraordinarily high mortality rate (>50%) for those Covid-19 patients who underwent MV. Considering the mechanical nature of MV, the high mortality rate is highly possible to be associated with mechanical stretch-induced lung injury during MV. Thus, it is imperative to understand the MV-induced pathological alterations in the respiratory system and corresponding mitigation measures in order to improve the therapy of critically ill Covid-19 patients. Ventilator-induced lung injury in therapy of critically ill Covid-19 patients involves several biomechanical factors and mechanisms, including changes in respiratory parameters, inflammatory cytokines storm, ciliary-mucus system, airway smooth muscle cells, lung fibrosis, and stretch-activated cell signaling. It is hoped that these biomechanical issues can be diligently investigated, so as to provide insights for optimizing the therapy for Covid-19 as well as other respiratory diseases.

Effect of sanguinarine on biomechanics of rat airway smooth muscle cells / 生物医学工程学杂志

This study aimed to evaluate the effect of sanguinarine on biomechanical properties of rat airway smooth muscle cells (rASMCs) including stiffness, traction force and cytoskeletal stress fiber organization. To do so, rASMCs cultured were treated with sanguinarine solution at different concentrations (0.005~5 μmol/L) for 12 h, 24 h, 36 h, and 48 h, respectively. Subsequently, the cells were tested for their viability, stiffness, traction force, migration and microfilament distribution by using methylthiazolyldiphenyl-tetrazolium bromide assay, optical magnetic twisting cytometry, Fourier transform traction microscopy, scratch wound healing method, and immunofluorescence microscopy, respectively. The results showed that at concentration below 0.5 μmol/L sanguinarine had no effect on cell viability, but caused dose and time dependent effect on cell biomechanics. Specifically, rASMCs treated with sanguinarine at 0.05 μmol/L and 0.5 μmol/L for 12 and 24 h exhibited significant reduction in stiffness, traction force and migration speed, together with disorganization of the cytoskeletal stress fibers. Considering the essential role of airway smooth muscle cells (ASMCs) biomechanics in the airway hyperresponsiveness (AHR) of asthma, these findings suggest that sanguinarine may ameliorate AHR via alteration of ASMCs biomechanical properties, thus providing a novel approach for asthma drug development.

Research on the range of motion measurement system for spine based on LabVIEW image processing technology / 生物医学工程学杂志

A measurement system based on the image processing technology and developed by LabVIEW was designed to quickly obtain the range of motion (ROM) of spine. NI-Vision module was used to pre-process the original images and calculate the angles of marked needles in order to get ROM data. Six human cadaveric thoracic spine segments T7-T10 were selected to carry out 6 kinds of loads, including left/right lateral bending, flexion, extension, cis/counterclockwise torsion. The system was used to measure the ROM of segment T8-T9 under the loads from 1 Nm to 5 Nm. The experimental results showed that the system is able to measure the ROM of the spine accurately and quickly, which provides a simple and reliable tool for spine biomechanics investigators.

A flexion loading system for knee biomechanics research / 生物医学工程学杂志

It is important to design and build a kinetic loading system for flexing movement of knee joint to study knee biomechanics. The system reported here includes driving device, control device, and flexion angle determination imaging system. The driving device was constructed with a stepper motor and a mechanical transmission with a serried of clamps, shanks and so on, and the driving device was controlled by the control device with micro-control unit, a computer and the serial 232. While the knee joint was driven to move by the stepper motor, the flexion angle of the knee was determined using imaging-based techniques. The system achieved accurate loading and control of speed, extent and duration of knee flexion, as well as fast and non-contract determination of flexion angle during knee flexing movement. The system is simple to build, easy to operate, highly accurate and reliable and it provides an important tool for the study of knee biomechanics, and potentially provides a tool for helping patients of knee surgery during their post operation recovery training.

The study of beta2-adrenergic receptor gene polymorphism in Sanda athletes / 生物医学工程学杂志

This study observed the disposition of beta2-adrenergic receptor (beta2-AR) Arg16Gly genotype and allele frequency among Sanda athletes in China, and investigated the diversity about the single nucleotide polymorphism of beta2-AR Arg16Gly between Sanda athletes and normal people of Han nationality in China. We used the technique of allele specified primer polymerase chain reaction to detect ADRB2 gene polymorphism of Sanda athletes (61 subjects) and normal Han nation people (50 subjects). The results showed there were significant differences about AA genotype, A allele, and G allele between Sanda athletes group and normal Han nation group (AA: chi2 = 6.646, P = 0.01, P < 0.05; A: chi2 = 4.003, P = 0.045, P < 0.05; G: chi2 = 4.003, P = 0.045, P < 0.05), and the frequency of AA genotype and A allele in the group of normal Han nation was higher than that in the group of Sanda athletes.