ABSTRACT
Cellular mechanics, a major regulating factor of cellular architecture and biological functions, responds to intrinsic stresses and extrinsic forces exerted by other cells and the extracellular matrix in the microenvironment. Cellular mechanics also acts as a fundamental mediator in complicated immune responses, such as cell migration, immune cell activation, and pathogen clearance. The principle of atomic force microscopy (AFM) and its three running modes are introduced for the mechanical characterization of living cells. The peak force tapping mode provides the most delicate and desirable virtues to collect high-resolution images of morphology and force curves. For a concrete description of AFM capabilities, three AFM applications are discussed. These applications include the dynamic progress of a neutrophil-extracellular-trap release by neutrophils, the immunological functions of macrophages, and the membrane pore formation mediated by perforin, streptolysin O, gasdermin D, or membrane attack complex.
Subject(s)
Microscopy, Atomic Force , NeutrophilsABSTRACT
BACKGROUND: Mechanical stimulation plays a necessary regulatory role in developing and repairing many organs and tissues in the human body. Except for biochemical factors, mechanical factors are considered as key regulatory factors that affect the behavior and function of dental pulp stem cells. OBJECTIVE: To review the role and effect of cellular mechanical stimulation on the biological behavior of dental pulp stem cells. METHODS: PubMed, Embase, Medline and CNKI databases were searched for relevant literatures using the keywords of “human dental pulp stem cells (hDPSCs), mechanical strain, mechanical stretch, mechanical tension, shear stress, cell proliferation, osteogenesis differentiation” in English and Chinese, respectively. Fifty-six articles were finally eligible for review, which were closely related to the proliferation and differentiation of dental pulp stem cells under cellular mechanical stimulation. RESULTS AND CONCLUSION: Cellular mechanical stimulation is an important biological factor affecting cell proliferation, differentiation, apoptosis and protein expression. Dental pulp stem cells are mesenchymal stem cells derived from the dental pulp tissue, and their biological behaviors are also affected by cellular mechanical stimulation. Cellular mechanical stimulation is involved in the proliferation, odontogenesis/osteogenesis of dental pulp stem cells. When the dentin is subjected to fluid flow forces, mechanoreceptors are activated to regulate and maintain the integrity of tooth structure. Signal pathways that mediate the biological behavior of dental pulp stem cells include MAPK, Wnt, Akt, BMP-7, and Nrf2/HO-1, which are involved in promoting and inhibiting the proliferation and odontogenesis/osteogenesis of dental pulp stem cells to varying degrees.
ABSTRACT
Objective To develop a new set of algorithms for high-resolution cellular traction force recovery based on two-dimensional Fourier domain by addressing the ill-posed nature of classic cellular force traction recovery. Methods By exploring the inherent characteristics and rules of displacement data on the substrates and Green’s function in the Fourier domain, the phenomenon of ill-posed deconvolution arising in cellular force traction recovery was investigated and a set of self-adaptive filtering algorithms was consequently developed to remarkably restrain the high frequency noise amplification. Results The ill-posed nature of classical Fourier transform traction cytometry (FTTC) made cellular traction force recovery extremely unstable, especially for relatively dense displacement data sampling. In contrast, the proposed self-adaptive filtering algorithms based on FTTC could make cellular traction force distribution more stable and reliable, as the effect of high frequency noise in displacement field on recovery results was weakened significantly. Conclusions This new technique for cellular traction force recovery can effectively suppress the noise and therefore improve the stability of force recovery procedure and spatial resolution, which is expected to find wider application in the study of cell substrate interactions.
ABSTRACT
Cell-substrate interactions are relevant for a number of biological and clinical applications e.g. to determine the effectiveness of medical implants. Cells are natural transducers that respond to and sense signals originating in their microenvironment. One important cell signaling mechanism is known as chemo-mechanical transduction. This refers to the use of external mechanical cues to initiate internal biochemical cellular processes and vice versa. One key factor to characterize and understand these interactions is the evaluation of the mechanical forces present at the cell-substrate interface. Recent advances in the micro and nanotechnology fields have allowed the development of new tools for the measurement of cellular and tissue forces. These tools have provided a means to study extremely low cellular and subcellular forces (pN-µN) as well as detailed small-scale tissue mechanics. This paper will review some of the most significant approaches to characterize the mechanical properties of cells and tissues at the micro-scale. Material properties, device fabrication, and design issues will be discussed.
Las interacciones célula-sustrato juegan un papel fundamental en gran número de aplicaciones biológicas y clínicas. Las células son transductores naturales que sensan y responden a señales en su entorno fisiológico. Uno de los mecanismos más importantes empleados en la caracterización de interacciones celulares es la transducción químico-mecánica, la cual se basa en la implementación de señales externas que se aplican a la célula con el fin de inducir diversos procesos bioquímicos al interior de ésta y viceversa. Los avances alcanzados en el campo de la micro y nanotecnología han permitido el desarrollo de nuevas herramientas para medir fuerzas a nivel celular o incluso sub-celular (pN-µN), y dilucidar la mecánica de los tejidos en la escala micrométrica. La presente revisión literaria describe algunos de los micro-dispositivos empleados actualmente para caracterizar las propiedades mecánicas de las células y tejidos en la micro-escala.