1,026 research outputs found
A practical review on the measurement tools for cellular adhesion force
Cell cell and cell matrix adhesions are fundamental in all multicellular
organisms. They play a key role in cellular growth, differentiation, pattern
formation and migration. Cell-cell adhesion is substantial in the immune
response, pathogen host interactions, and tumor development. The success of
tissue engineering and stem cell implantations strongly depends on the fine
control of live cell adhesion on the surface of natural or biomimetic
scaffolds. Therefore, the quantitative and precise measurement of the adhesion
strength of living cells is critical, not only in basic research but in modern
technologies, too. Several techniques have been developed or are under
development to quantify cell adhesion. All of them have their pros and cons,
which has to be carefully considered before the experiments and interpretation
of the recorded data. Current review provides a guide to choose the appropriate
technique to answer a specific biological question or to complete a biomedical
test by measuring cell adhesion
Cell sorting in a Petri dish controlled by computer vision.
Fluorescence-activated cell sorting (FACS) applying flow
cytometry to separate cells on a molecular basis is a widespread
method. We demonstrate that both fluorescent and unlabeled live
cells in a Petri dish observed with a microscope can be
automatically recognized by computer vision and picked up by a
computer-controlled micropipette. This method can be routinely
applied as a FACS down to the single cell level with a very
high selectivity. Sorting resolution, i.e., the minimum distance
between two cells from which one could be selectively removed
was 50-70 micrometers. Survival rate with a low number of 3T3
mouse fibroblasts and NE-4C neuroectodermal mouse stem cells was
66 +/- 12% and 88 +/- 16%, respectively. Purity of sorted
cultures and rate of survival using NE-4C/NE-GFP-4C co-cultures
were 95 +/- 2% and 62 +/- 7%, respectively. Hydrodynamic
simulations confirmed the experimental sorting efficiency and a
cell damage risk similar to that of normal FACS
Microdevices and Microsystems for Cell Manipulation
Microfabricated devices and systems capable of micromanipulation are well-suited for the manipulation of cells. These technologies are capable of a variety of functions, including cell trapping, cell sorting, cell culturing, and cell surgery, often at single-cell or sub-cellular resolution. These functionalities are achieved through a variety of mechanisms, including mechanical, electrical, magnetic, optical, and thermal forces. The operations that these microdevices and microsystems enable are relevant to many areas of biomedical research, including tissue engineering, cellular therapeutics, drug discovery, and diagnostics. This Special Issue will highlight recent advances in the field of cellular manipulation. Technologies capable of parallel single-cell manipulation are of special interest
Intracellular delivery by membrane disruption: Mechanisms, strategies, and concepts
© 2018 American Chemical Society. Intracellular delivery is a key step in biological research and has enabled decades of biomedical discoveries. It is also becoming increasingly important in industrial and medical applications ranging from biomanufacture to cell-based therapies. Here, we review techniques for membrane disruption-based intracellular delivery from 1911 until the present. These methods achieve rapid, direct, and universal delivery of almost any cargo molecule or material that can be dispersed in solution. We start by covering the motivations for intracellular delivery and the challenges associated with the different cargo typesñYsmall molecules, proteins/peptides, nucleic acids, synthetic nanomaterials, and large cargo. The review then presents a broad comparison of delivery strategies followed by an analysis of membrane disruption mechanisms and the biology of the cell response. We cover mechanical, electrical, thermal, optical, and chemical strategies of membrane disruption with a particular emphasis on their applications and challenges to implementation. Throughout, we highlight specific mechanisms of membrane disruption and suggest areas in need of further experimentation. We hope the concepts discussed in our review inspire scientists and engineers with further ideas to improve intracellular delivery
Cell Biomechanical Modeling Based on Membrane Theory with Considering Speed Effect of Microinjection
As an effective method to deliver external materials into biological cells,
microinjection has been widely applied in the biomedical field. However, the
cognition of cell mechanical property is still inadequate, which greatly limits
the efficiency and success rate of injection. Thus, a new rate-dependent
mechanical model based on membrane theory is proposed for the first time. In
this model, an analytical equilibrium equation between the injection force and
cell deformation is established by considering the speed effect of
microinjection. Different from the traditional membrane-theory-based model, the
elastic coefficient of the constitutive material in the proposed model is
modified as a function of the injection velocity and acceleration, effectively
simulating the influence of speeds on the mechanical responses and providing a
more generalized and practical model. Using this model, other mechanical
responses at different speeds can be also accurately predicted, including the
distribution of membrane tension and stress and the deformed shape. To verify
the validity of the model, numerical simulations and experiments are carried
out. The results show that the proposed model can match the real mechanical
responses well at different injection speeds.Comment: 10 pages, 12 figures, submitted to IEEE TMech
Estimation of Injection Volume in Capillary Microinjection Using Electrical Impedance Measurement
Capillary pressure microinjection (CPM) is a tool for transporting small sample volumes into living cells utilizing a sharp glass pipette and pressure pulses. The automation level of the current state-of-the-art microinjection devices is low and this makes the technique slow, imprecise and inefficient. The objective of this thesis work is to develop a method to estimate the injection volume in the capillary pressure microinjection technique of living adherent cells. This method would improve the reliability and repeatability of CPM and facilitate automating the injection procedure.
Due to the extremely small dimensions involved in the process, a straight measurement of the injection volume is not possible. The strategy used in this work is to generate a mathematical model for the injection volume as a function of the injection pressure and the pipette electrical resistance. A measurement setup is built around a microinjection system to gather data for constructing the model. The injection pressure is measured with a pressure sensor, the pipette electrical resistance is determined using a custom-made impedance measurement circuitry and the injection volume is estimated by using a fluorescent dye as the injection liquid and recording image data from the injections. Several injection pressures and micropipette sizes are used to achieve data extensively enough. A MATLAB based automated algorithm is generated to handle the measurement data and organize the results efficiently.
The measurement results give a rough estimate of the relationship between the injection volume, the injection pressure and the pipette electrical resistance. However, a reliable model cannot be built based on the data. The reason is the rather limited amount of suitable measurement data for modelling it was possible to collect due to the numerous error situations. Nevertheless, new important information of the nature of the microinjection procedure is obtained and valuable observations on measurements connected to microinjection are made. Further studies must be done to solve the problems in the tests to be able to gather the data more efficiently and construct the actual model. /Kir1
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