Cell-patterning using poly (ethylene glycol)-modified magnetite nanoparticles.
Akiyama H, Ito A, Kawabe Y, Kamihira M, Department of Chemical Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2009.
Summary: In tissue engineering, cell patterning is used to construct layers of different cell types in the goal of fabricating functional tissues and organs that similar to the native ones. In this article, cell patterning using PEG-Mags (polyethylene glycol- modified magnetic particles) and magnetic force is developed. A substrate surface can be chemically processed to control cell adhesion by varying hydrophilicity, while PEG-Mags region on the surface can resist the binding of cells. So when cells are seeded onto the surface, only the native region of substrate surface forms monolayer of cells. When PEG-Mags are added to a tissue dish, a 96-magnet plate will attract these magnetite particles into the pattern of magnets. Cells line are seeded and incubated for one day to form the designated pattern. Then the magnet will be removed and the dish will be washed with PBS to remove PEG-Mags and unattached cells. Another cell line can be seeded into the dish to grow a coculture of heterotypic cells.
Cell lines used in the experiment are mouse fibroblast NIH3T3, mouse myoblast C2C12 and immortalized human keratinocytes HaCaT. The stability of cell patterns is concerned since these cell lines are highly productive and fast in migration. This might become a problem if the dish is cultured for too long. Furthermore, the toxicity of the magnetite particles in cellular uptake is a main concern on cell viability. Experiment shows that PEG-Mags is safer choice than others such as aminosilane-Mags. The article suggested that PEG-Mags is very biocompatible and low toxic so they are employed for a novel cell-patterning method.
Significance: Cell-patterning has a very significant role in tissue engineering and cell biology so this simple and speedy method can be a very promising tool in the fields since recent methods in control cell adhesion by modifying surface hydrophilicity is time consuming and high cost. More researches will be conducted to such as cell patterning using primary cells to find the practical application of this novel method.
2 comments:
Cell patterning seems very interesting. The method described here seems to be very limited though. I don’t see how anything more than merely a few cell layers could be patterned. This would be a significant limitation to doing this in 3D, which would be necessary for tissue engineering. Also, even if many cell layers could be stacked to stimulate a 3D tissue, I expect this to take a very long time—to long to be practical. Furthermore, it is important to know what the resolution of patterning is. Most likely, the resolution is limited by either the precision of the magnetic field generator or by the size of the beads.
As for the cells, it is important to consider the how well the cells attach to each other between the multiple layers. Also, knowing that cells in 3D tissues typically have an ideal packing structure, it is important to consider how well the cells stack against one another. In particular, if the ultimate goal is to generate tissue, the stacking orientation and symmetry of the cells may play a role in how well the tissue holds up.
Further studies should examine the cellular behavior at the magnet-cell interface and could investigate the cellular behavior at the fringes of the pattern.
The co-culture possibility seems interesting. Have there been any studies on the effect PEG-Mags can have on cells?
What is the resolution of this patterning method? I’m assuming the particles are not bigger than the size of a single cell. And also, what is the exact mechanism of preventing adhesion? Is it the particles themselves that are not permissive, or the magnetic force?
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