Chips, in most incarnations, are bad for the heart. Whether you’re frying them, baking them into cookies, or carrying one on your shoulder, chips are not cardiologist-approved. A new paper from Kevin Healy’s lab aims to mend this relationship with a microfluidic chip that is able to coax human induced stem cells into beating 3D cardiac tissue.
Figure 1: This is your heart on a chip. Image credits: Heart-oid via Movie S3 of Mathur et al.
Heart Problems for Pharma
Screening drugs for cardiac effects is a notoriously expensive problem in the pharmaceutical industry. The issue is largely caused by the inaccurate preclinical testing systems; animal hearts and cultured cell lines just don’t respond like human hearts.
Enter human induced pluripotent stem cells (hiPSCs), which can provide a steady source of real human cardiac cells. Induced cardiac cells have been grown in dishes, but the heart is a complex 3-dimensional beast, and flat tissue cultures don’t capture its intricacies. Other researchers have grown induced cardiac cells into 3D structures, but they didn’t have continuous nutrient and drug exchange that living hearts get from blood circulation. To build a more realistic heart, this new study combined human induced cardiac cells with a clever microfluidic device that provided continuous circulation with no shear forces.
The Path to a Man’s Proto-heart is Through 2 μm-wide Feeder Channels
The heart chip is a relatively simple concept – it has a 150 μm wide main chamber for cardiac cells, surrounded by two artery channels through which nutrients are continuously fed via 2 μm wide microchannel capillaries. Just like in a real body, nutrients are exchanged by diffusion only, with no shear flow to buffet the proto-heart. To load the chip, the group differentiated hiPSCs for 15-20 days, and then gently sucked them into the main channel. The channel was coated with fibronectin, onto which the cells aligned, formed a layered 3D structure, and started beating.
When the group dosed their heart-oids with four different heart-affecting drugs, they found more accurate dose-response curves than in previous tissue culture studies. Combined with the low cost and small scale of this heart chip, this high accuracy could make cardiac drug development much simpler, quicker, and cheaper. Rumor has it they’ve been in talks with Cupid as well.
Don’t miss a beat of this exciting research from Mathur et al. in Scientific Reports, March 2015