ObjectiveTo review the chondrocyte survival microenvironment and the research progress of the application of microfluidic chips in constructing the chondrocyte microenvironment. MethodsRecent literature about the role of microenvironment in the regulation of chondrocytes and the application of microfluidic chips in constructing the chondrocyte microenvironment was reviewed and analyzed. ResultsRegulating the microenvironment of chondrocyte mainly involves extracellular matrix microenvironment, mechanical microenvironment, electric microenvironment, and hypoxic microenvironment. Currently, the related research of chondrocyte microenvironment based on microfluidic system mainly involves biochemical stimuli, mechanical stimuli, production of biomimetic scaffold materials, and so on. ConclusionIt will be helpful for constructing cartilage tissue being closer to the physiological function in the future to deeply understand chondrocyte survival environment and to mimic the microenvironment in vivo required by chondrocyte development as possible by using microfluidic chips.
ObjectiveTo preliminary study on the feasibility of constructing three-dimensional (3D) hippocampal neural network in vitro by using microfluidic technology.MethodsA network patterned microfluidic chip was designed and fabricated by standard wet etching process. The primary hippocampal neurons of neonatal Sprague Dawley rats were isolated and cultured, and then inoculated on microfluidic chip for culture. Immunofluorescence staining was used to observe the growth of hippocampal neurons at 3, 5, and 7 days of culture and electrophysiological detection of hippocampal neuron network at 7 days of culture.ResultsThe results showed that the number of hippocampal neurons increased gradually with the prolongation of culture time, and the neurite of neurons increased accordingly, and distributed uniformly and regularly in microfluidic chip channels, suggesting that the 3D hippocampal neuron network was successfully constructed in vitro. Single and multi-channel spontaneous firing signals of hippocampal neuronal networks could be detected at 7 days of culture, suggesting that neuronal networks had preliminary biological functions.ConclusionPatterned microfluidic chips can make hippocampal neurons grow along limited paths and form 3D neuron networks with corresponding biological functions such as signal transduction, which lays a foundation for further exploring the function of neuron networks in vitro.
Cell migration is defined as the directional movement of cells toward a specific chemical concentration gradient, which plays a crucial role in embryo development, wound healing and tumor metastasis. However, current research methods showed low flux and are only suitable for single-factor assessment, and it was difficult to comprehensively consider the effects of other parameters such as different concentration gradients on cell migration behavior. In this paper, a four-channel microfluidic chip was designed. Its characteristics were as follows: it relied on laminar flow and diffusion mechanisms to establish and maintain a concentration gradient; it was suitable for observation of cell migration in different concentration gradient environment under a single microscope field; four cell isolation zones (20 μm width) were integrated into the microfluidic device to calibrate the initial cell position, which ensured the accuracy of the experimental results. In particular, we used COMSOL Multiphysics software to simulate the structure of the chip, which demonstrated the necessity of designing S-shaped microchannel and horizontal pressure balance channel to maintain concentration gradient. Finally, neutrophils were incubated with advanced glycation end products (AGEs, 0, 0.2, 0.5, 1.0 μmol·L−1), which were closely related to diabetes mellitus and its complications. The migration behavior of incubated neutrophils was studied in the 100 nmol·L−1 of chemokine (N-formylmethionyl-leucyl-phenyl-alanine) concentration gradient. The results prove the reliability and practicability of the microfluidic chip.
Microfluidics is the science and technology to manipulate small amounts of fluids in micro/nano-scale space. Multiple modules could be integrated into microfluidic device, and due to its advantages of microminiaturization and controllability, microfluidics has drawn extensive attention since its birth. In this paper, the literature data related to microfluidics research from January 1, 2006 to December 31, 2021 were obtained from Web of Science Core Collection database. CiteSpace 5.8.R3 software was used for bibliometrics analysis, so as to explore the research progress and development trends of microfluidics research at home and abroad. Based on the analysis of 50 129 articles, it could be seen that microfluidics was a hot topic of global concern, and the United States had a certain degree of authority in this field. Massachusetts Institute of Technology and Harvard University not only had a high number of publications, but also had strong influence and extensive cooperation network. Combined with ultrasonic, surface modification and sensor technology, researchers constructed paper-based microfluidic, droplet microfluidic and digital microfluidic platforms, which were applied in the field of immediate diagnosis, nucleic acid and circulating tumor cell analysis of in vitro diagnosis and organ-on-a-chip. China was one of the countries with a high level of research in the field of microfluidics, while the industrialization of high-end products needed to be improved. As people’s demand for disease risk prediction and health management increased, promoting microfluidic technological innovation and achievement transformation is of great significance to safeguard people’s life and health.
Reduced chemotactic migration of polymorphonuclear neutrophil (PMN) in sepsis patients leads to decreased bacterial clearance and accelerates the progression of sepsis disease. Quantification of PMN chemotaxis in sepsis patients can help characterize the immune health of sepsis patients. Microfluidic microarrays have been widely used for cell chemotaxis analysis because of the advantages of low reagent consumption, near-physiological environment, and visualization of the migration process. Currently, the study of PMN chemotaxis using microfluidic chips is mainly limited by the cumbersome cell separation operation and low throughput of microfluidic chips. In this paper, we first designed an inertial cell sorting chip to achieve label-free separation of the two major cell types by using the basic principle that leukocytes (mainly granulocytes, lymphocytes and monocytes) and erythrocytes move to different positions of the spiral microchannel when they move in the spiral microchannel under different strength of inertial force and Dean's resistance. Subsequently, in this paper, we designed a multi-channel cell migration chip and constructed a microfluidic PMN inertial label-free sorting and chemotaxis analysis platform. The inertial cell sorting chip separates leukocyte populations and then injects them into the multi-channel cell migration chip, which can complete the chemotaxis test of PMN to chemotactic peptide (fMLP) within 15 min. The remaining cells, such as monocytes with slow motility and lymphocytes that require pre-activation with proliferative culture, do not undergo significant chemotactic migration. The test results of sepsis patients (n=6) and healthy volunteers (n=3) recruited in this study showed that the chemotaxis index (CI) and migration velocity (v) of PMN from sepsis patients were significantly weaker than those from healthy volunteers. In conclusion, the microfluidic PMN inertial label-free sorting and chemotaxis analysis platform constructed in this paper can be used as a new tool for cell label-free sorting and migration studies.
[Abstract]Blood biochemical indicators are an important basis for the diagnosis and treatment by doctors. The performance of related instruments, the qualification of operators, the storage method and time of blood samples and other factors will affect the accuracy of test results, which is difficult to meet the clinical needs of rapid detection and early screening of diseases. Point-of-care testing (POCT) is a new diagnostic technology with the characteristics of instant, portability, accuracy and efficiency. Microfluidic chips can provide an ideal experimental reaction platform for POCT. This paper summarizes the existing detection methods for common biochemical indicators such as blood glucose, lactic acid, uric acid, dopamine and cholesterol, and focuses on the application status of POCT based on microfluidic technology in blood biochemistry. It also summarizes the advantages and challenges of existing methods and prospects for development. The purpose of this paper is to provide relevant basis for breaking through the technical barriers of microfluidic and POCT product development in China.