BioMEMS for Cell Biology - Introduction to BioMEMS - page 365

he author's group (University of Washington, Seattle) in collaboration with Lisa Horowitz
from Linda Buck's laboratory at the Fred Hutchinson Cancer Research Center (Seattle) has used
large PDMS microwell arrays to screen for odorant responses from dissociated mouse olfactory
sensory neurons (OSNs). he microwell array was integrated into the loor of a simple nine-inlet
microluidic device ( Figure 6.73a and b ). Introducing a cell suspension into the chamber traps
the OSNs into the microwells with high eiciency ater the low is restarted to remove excess
cells ( Figure 6.73c ). he array allows for simultaneously screening more than 20,000 cells using
calcium imaging, of which approximately 2900 were KCl-responsive (and assumed to be OSNs)
by the end of the experiment. herefore, the vast majority of the olfactory receptor space (mice
express ~1000 olfactory receptors) are represented in the experiment. During the experiment,
the cells also responded to one or more of four chemicals, chosen from a group of fruity pleasant
smells (vanillin, berry, geraniol, and banana), and they did not respond to two control pulses
of DMSO (the solvent in which the odorants are dissolved). he results conirmed the common
inding that “broadly tuned” cells (those that respond to a variety of compounds) are more
abundant, and “narrowly tuned” cells are the least abundant ones (except for those tuned to
benzyl acetate; see the Venn diagram in Figure 6.73d ).

6.5.6 Glial Biology
Signaling between glia and neurons is vital for the development and physiology of the CNS.
Micropatterning and microluidic techniques ofer tools to accurately control the signaling
between diferent cell types by controlling the spacing between microfabricated patterns. A team
led by Marc Porter and Phil Haydon, both formerly of Iowa State University, coated glass slides
with (cell-adhesive) PLL, microluidically patterned them with (cell-repellent) agarose tracks,
and plated astrocytes on top of them ( Figure 6.74a ). his team was able to settle a long-standing

PDMS

a

Agarose Polylysine

Agarose

Polylysine

PDMS

Glass

b 2s

4s 6s 8s 10s 12s 14s

Control

16s 18s 20s 22s 24s 26s 28s

4s 8s 12s 16s 20s 24s 28s

c

With ATF inhibitor

300 µm 0%

500%

FIGURE 6.74 Transmission. of. calcium. waves. across. microscale. gaps. between. glial. cells.. (From.
Hajime.Takano,.Jai-Yoon.Sul,.Mary.L..Mazzanti,.Robert.T..Doyle,.Philip.G..Haydon,.and.Marc.D..
Porter,. “Micropatterned. substrates:. Approach. to. probing. intercellular. communication. pathways,”.
Anal. Chem. .74,.4640-4646,.2002..Figure.contributed.by.Phil.Haydon.)