Theodore T Tower | PubMed Health

PubMedDate not supplied

Cell patterning on biological gels via cell spraying through a mask.

We present an easily applicable and inexpensive method for patterning cells on arbitrary surfaces including biological gels with little loss of viability or function. Single-cell suspensions of human umbilical vein endothelial cells and NIH 3T3 fibroblasts were sprayed with an off-the-shelf airbrush through a mask to create 100-microm scale patterns on collagen gels. Three-dimensional patterns were created by layering a collagen gel on top of the first pattern and patterning the top gel. Coculture of rat hepatocytes with NIH 3T3 patterns on collagen gels resulted in localized increased activity of cytochrome P-450 along the pattern. These results suggest that cell spraying is a useful tool for the study of heterotypic cellular interactions and tissue-engineering applications on biologically relevant matrices, and for the creation of three-dimensional cell patterns in vitro.

Animals↗

PubMedDate not supplied

Fiber alignment imaging during mechanical testing of soft tissues.

A method to image fiber alignment during mechanical testing of soft tissues was developed based on quantitative polarized light microscopy. Images were acquired after passing light through a rotating polarizer, a tissue sample, and an effective circular analyzer at multiple polarizer positions during uniaxial mechanical testing. The image set was analyzed offline using harmonic analysis to generate an alignment image, which contains the direction and strength of alignment at each image pixel. Alignment images of the entire tissue sample were generated every 3-5 s during the mechanical test allowing stress-strain behavior to be correlated with fiber alignment. Loading of fresh tissue-equivalent samples in the direction normal to the initial direction of fiber alignment revealed a spatially inhomogeneous realignment into the loading direction, with most realignment occurring near the free edges undergoing maximum lateral contraction and prior to significant load developing. Glutaraldehyde-fixed samples, in contrast, showed little realignment until yielding occurred.

Animals↗