WebZine
2017.05
What's New
Researchers Grow Brain Cells on a Chip
By Emily Waltz
Posted 18 May 2017 | 20:00 GMT
Every human thought starts with a signal traveling from one neuron to another in the brain. Yet we know relatively little about how these connections form. In an effort to watch that process unfold, Australian researchers engineered a nanowire scaffold on a semiconductor chip that enables brain cells to grow and form circuits. The scientists described their device recently in the journal Nano Letters. The neural scaffold falls far short of any brain-on-a-chip that futurists might imagine. But it does provide a way for scientists to guide the growth of neurons and study their connectivity, says Vini Gautam, a biomaterials engineer at Australian National University who led the study.
New Bioprinter Makes It Easier to Fabricate 3D Flesh and Bone
By Eliza Strickland
Posted 16 May 2017 | 20:00 GMT
The ideal 3D bioprinter, says tissue engineering expert Y. Shrike Zhang, would resemble a breadmaker: “You’d have a few buttons on top, and you’d press a button to choose heart tissue or liver tissue.” Then Zhang would walk away from the machine while it laid down complex layers of cells and other materials.
The technology isn’t quite there yet. But the new BioBot 2 printer seems a step in that direction. The tabletop device includes a suite of new features designed to give users easy control over a powerful device, including automated calibration; six print heads to extrude six different bioinks; placement of materials with 1-micrometer precision on the x, y, and z axes; and a user-friendly software interface that manages the printing process from beginning to end.
That has been a challenge for scientists trying to recreate neural circuitry in the lab. Neurons in the brain connect and communicate in a highly ordered way. But in the lab, the cells tend to reconstruct randomly and suffer from experimental limitations that render the circuitry nothing like the real thing in the brain.
“Understanding how neural circuits form in the brain is one of the fundamental questions in neuroscience,” Gautam says. Those connections form the basis for how we process information, and understanding them is key to developing treatments for mental disorders, she says.
Gautam and her colleagues Chennupati Jagadish and Vincent Daria wanted to create an environment where they could both direct the growth of neurons and allow them to make natural, synchronized connections. So they made a nanowire scaffold made of indium phosphide. The semiconductor material is well known for applications in nanoscale electronics such as in the fabrication of LEDs, solar cells. But no one had used it to interface with brain cells, Gautam says.
The researchers arranged the nanowires in a square lattice pattern, placed about 50 neuronal cells from rodents on each scaffold, put it in a culturing medium and watched them grow. After a few days, the neurons had produced outgrowths called neurites.
BioBots cofounder and CEO Danny Cabrera says the BioBot 2’s features are a result of collaboration with researchers who work in tissue engineering.
“We’ve been working closely with scientists over the past year and a half to understand what they need to push this work forward,” he says. “What we found is that they needed more than just a bioprinter—and we had to do more than just develop a new robot.”
The company’s cloud-based software makes it easy for users to upload their printing parameters, which the system translates into protocols for the machine. After the tissue is printed, the system can use embedded cameras and computer-vision software to run basic analyses. For example, it can count the number of living versus dead cells in a printed tissue, or measure the length of axons in printed neurons. “This platform lets them measure how different printing parameters, like pressure or cellular resolution, affect the biology of the tissue,” Cabrera says.
The BioBot 1 hit the market in 2015 and sells for US $10,000. The company is now taking orders for the $40,000 BioBot 2, and plans to ship later this year.
Each of the BioBot 2’s print heads can cool its bioink to 4 degrees Celsius or heat it to 200 degrees Celsius. The printbed is also temperature-controlled, and it’s equipped with visible and ultraviolet lights that trigger cross-linking in materials to give make printed forms more solid.
Cabrera says the temperature controls make it easier to print collagen, a principal component of connective tissue and bone, because it cross-links at colder temperatures. “A lot of people were hacking their bioprinters to get collagen to print,” Cabrera says. “Some were printing in the refrigerator.”
While some researchers won’t be interested in using the six print heads to make tissue composed of six different materials, Cabrera says the design also allows researchers to multiplex experiments. For example, if researchers are experimenting with the concentration of cells in a bioink, this setup allows them to simultaneously test six different versions. “That can save weeks if you have to wait for your cells to grow after each experiment,” Cabrera says.
And the machine can deposit materials not only on a petri dish, but also into a cell-culture plate with many small wells. With a 96-well plate, “you could have 96 lilttle experiments,” says Cabrera.
