Cell Fusion in Microfluidics

Cell Fusion in Microfluidics, Fig. 2 (a) Device layout for micro orifice-based fusion, (b) cell pairing, (c) cell fusion, (d) isolation of the fused cells... 

Cell Fusion in Microfluidics, Fig. 3 (a) Model for two cells in contact at a micro orifice, (b) Numerical analysis result for induced membrane potential for angles 0-30° (Adapted with permission from Ref. [5])... 

Cell Fusion in Microfluidics, Fig. 7 Cytoplasmic transplantation with micro orifice-based fusion (Adapted with... 

Although these examples indicate that cell fusion is a revolutionary technique enabling creation of hybrid cells with unique properties, it has certain limitations such as extremely low fusion yield and compromised cell viability. These limitations are mainly based on the conventional techniques used for cell fusion. With the recent advances in microfabrication and microfluidic technology, it is anticipated that these limitations... 

Microfluidics offers a convenient way to develop miniaturized cell fusion systems. The literature shows numerous examples of miniaturized electrofusion systems [4]. However, results of this work have shown that miniaturization alone does not address the critical limitations affecting the efficiency of cell fusion. Results show that simply miniaturizing electrofusion systems only produce efficiency levels in line with that of the conventional methods. 

Quantitative studies of chemotactic signaling require experimental techniques that can expose single cells to chemical stimuli with high resolution in both space and time. Recently, we have introduced the method of flow photolysis (Anal. Chem. 79 3940-3944, 2007), which combines microfluidic techniques with the photochemical release of caged compounds. This method allows us to tailor chemical stimuli on the length scale of individual cells with subsecond temporal resolution. In this chapter, we provide a detailed protocol for the setup of flow photolysis experiments and exemplify this versatile approach by initiating membrane translocation of fluorescent fusion proteins in chemotactic Dictyostdium discoideum cells. 

The efficiency of the micro orifice-based fusion method has been experimentally demonstrated as a high-yield (>90 %) fusion process [6]. A microfluidic device consists of two microfluidic channels separated with micro slit array was fabricated in PDMS (Fig. 4). The fabricated microfluidic channel was integrated with a substrate with patterned electrodes. Two different types of cells were introduced into each microfluidic channel. Cell pairing was achieved by using dielectrophoresis and... 

Micro orifice-based fusion allows physical immobilization of the fused cell pairs, which opens the possibility of post-fusion manipulation. One example of such manipulation is the cytoplasmic transplantation [7]. Figure 7 shows two cells in a microfluidic channel. The cells are fused using the micro orifice seen in the middle. The diameter of the orifice (3 pm) is much smaller than that of cell nucleus. By creating a pressure difference between left and right side of the orifice, it is possible to transfer the cytoplasmic content from one cell to the other. The example Illustrated m Fig. 7 demonstrates the case when the pressure difference Is obtained by applying different flow rates in each channel. The cytoplasmic transfer can be confirmed from the... 

The formation of skeletal muscle tissue in vivo involves the determination of precursor cells to the myoblastic pathway, fusion of myoblasts into multinucleated myotubes, and maturation into muscle fibers. Tourovskaia and colleagues [10] have developed a microfluidic cell culture system for myogenesis studies that provides control over the external environment to fuUy recapitulate myogenic differentiation in vivo and allows the manipulation of subcellular domains within mature myotubes for simulation of postsynaptic differentiation and further modula-... 

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