A Possible Weapon Against the Pandemic: Printing Human Tissue

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As shortages of private protecting tools persist throughout the coronavirus pandemic, Three-D printing has helped to alleviate a few of the gaps. But Anthony Atala, the director of the Wake Forest Institute for Regenerative Medicine, and his crew are utilizing the course of in a extra modern means: creating tiny replicas of human organs — some as small as a pinhead — to check medicine to combat Covid-19.

The crew is setting up miniature lungs and colons — two organs notably affected by the coronavirus — then sending them in a single day by courier for testing at a biosafety lab at George Mason University in Fairfax, Va. While they initially created a few of the so-called organoids by hand utilizing a pipette, they’re starting to print these at scale for analysis as the pandemic continues to surge.

In the previous few years, Dr. Atala’s institute had already printed these tiny clusters of cells to check drug efficacy in opposition to micro organism and infectious ailments like the Zika virus, “but we never thought we’d be considering this for a pandemic,” he mentioned. His crew has the skill to print “thousands an hour,” he mentioned from his lab in Winston-Salem, N.C.

The foundation for a printed organ is known as a scaffold, made of biodegradable materials. To provide nutrition for the organoid, microscopic channels only 50 microns in diameter — roughly half the size of a human hair — are included in the scaffold. Once completed, the “bioink,” a liquid combination of cells and hydrogel that turns into gelatin, is then printed onto the scaffold “like a layer cake,” Dr. Atala said.

Another important part of the process is constructing blood vessels as part of the printing. Pankaj Karande, an associate professor of chemical and biological engineering at Rensselaer Polytechnic Institute, has been experimenting with skin printing since 2014 and recently had success in this step.

Using a cell known as a fibroblast, which helps with growth, along with collagen, as a scaffold, researchers at the institute printed the epidermis and dermis, the first two layers of skin. (The hypodermis is the third layer.) “It turns out the skin cells don’t mind being sheared,” Dr. Karande said, and they could ultimately survive.

But their work hit a snag: Without incorporating blood vessels, the skin eventually sloughs off. Collaborating with Jordan Pober and W. Mark Saltzman of Yale University, they eventually succeeded in constructing all three layers of human skin as well as vasculature, or blood vessels, which Dr. Karande said was essential to the skin’s surviving after it had been grafted.

The three began experimenting with integrating human endothelial cells, which line blood vessels, and human pericyte cells, which surround the endothelial cells, into the skin as it was printed. Eventually, after much trial and error, they were able to integrate the blood vessels with the skin and found that connections were formed between new and existing blood vessels.

While the work is preliminary — tested in mice — Dr. Karande said he was hopeful that the success in printing integrated skin and vasculature would set the stage for successful grafting in humans eventually.

The research, according to Dr. Karande, is painstaking and involves a lot of trial and error. “We have Plan A, which we often know won’t work and then we go down the list. We can often write about what works in five pages but have 5,000 pages of what didn’t work,” he added.

Dr. Gaharwar’s lab also is investigating whether human bone tissue can be printed for eventual transplantation. His hope, he says, is that in the future, patient radiographic scans can be translated into the exact shape needed for implantation, especially important in repairing craniofacial defects where the curvature needed can be difficult to recreate.

Like Dr. Gaharwar, Dr. Karande says that personalization is important. He says that his work has already shown that skin can be fabricated to match an individual’s color. And, because the skin is also critical in regulating body temperature, he is also working to engineer sweat glands into the skin, along with hair follicles.

“When we graft, we want to be able to recreate the full functionality of the skin,” Dr. Karande said. And by using the cells from a patient, rather than a donor, the risk of rejection is minimized or eliminated altogether.

Source link Nytimes.com

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