January 12, 2017

Twenty-first century science has been forever transformed by organs-on-chips, but the technology has only just begun to be tapped for its full potential.

Last month the National Institute of Biomedical Imaging and Bioengineering announced that scientists have created a “liver-in-a drop.” Utilizing advances in microfluidics, a team of researchers led by Professor David A. Weitz at Harvard University has developed a droplet that contains two essential types of liver cells – hepatocytes and fibroblasts – that can be used for drug testing.

Approximately 95 percent of all drugs that show promise in development fail when tested in human clinical trials, largely due to ineffective animal tests. Almost weekly the media reports on drugs that show great promise in studies with rats, mice or monkeys, only to fail when used in humans.

Dr. Weitz and his team have created a microfluidic device that generates thousands of droplets, each with the capacity to mimic liver function, hence the term “liver-in-a-drop.” Each droplet consists of a variety of cells in a 3D core-shell that function as artificial human tissue.

The past five years have seen the rapid development of organs-on-chips, in which bioengineering techniques use cultured live human cells to manufacture miniature devices that can mimic the structure and function of real human tissue and organs.

Much research has focused on the liver-on–a-chip because of the essential role the liver plays in drug metabolism.

Yet liver chips are complicated to make, and according to Dr. Weitz, they may lack uniformity and are difficult to modify. Using the droplet-based microfluidic technique, up to one thousand droplets per second can be generated, allowing huge numbers of drugs to be screened at varying combination and doses.

Each droplet functions like a mini experiment, and a single milliliter of fluid allows scientists to perform a million trials!

The liver in a drop is not expected to replace organ chips but will complement them by streamlining productivity and enabling high throughput screening of vast numbers of drugs.

“Currently, it is very time-consuming and expensive to develop new drugs,” explains Dr. Weitz. “One reason is that many drugs fail in clinical trials after animal studies, simply because animals are very different from humans. One promising means of solving this problem is to replace animal experiments with artificial human tissues that can be used to directly screen a drug.”

Droplet-based microfluidic technology can also be applied to creating other types of human microtissues to study a range of diseases. 

It is yet one more technology for creating sophisticated human tissues that can bring about the end to animal experiments.

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