Bioprinting Human Tissue

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Body on a Chip is a miniaturized system of human organoid structures that mimic the function of the heart, liver, lung, and blood vessels. Credit: Wake Forest Institute for Regenerative Medicine
Body on a Chip is a miniaturized system of human organoid structures that mimic the function of the heart, liver, lung, and blood vessels. Credit: Wake Forest Institute for Regenerative Medicine

Anthony Atala, MD, is the Director of the Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina. As a practicing surgeon and a researcher in the area of regenerative medicine, his work focuses on growing human cells and tissues. We spoke with Dr Atala about the role of bioprinting in urology and nephrology, its current applications and future potential.

1. Why should urologists and nephrologists find 3D bioprinting so exciting?

3D bioprinting is a way of scaling up the process of engineering replacement tissues in the lab. It's precise and reproducible, which might expand access to regenerative medicine therapies beyond small clinical trials.

Our team has successfully implanted lab-engineered bladders, skin, urine tubes, muscle, cartilage and vaginas into patients. 3D printing was not used, but the technology could potentially play a role in future.

2. Describe how you're using bioprinting in your current projects.

Through a multi-institutional, “Body on a Chip” effort funded by the Defense Threat Reduction Agency, we bioprinted a miniaturized system of human organoid structures that mimic the function of the heart, liver, lung, and blood vessels.

The goal of the project was to model the human body's response to harmful agents and to test potential therapies. Testing using “body on a chip” is expected to be superior to testing in animals because human cells are used, making the results more applicable to patients. The technology also is expected to be faster than animal testing and less expensive.

Through the expertise gained in this project, we are now pursuing related efforts, such as a project to bioprint mini tumors on a chip that can be used to determine how a patient's tumor will respond to various potential therapies. We are also bioprinting testicular organoids that can potentially be used to evaluate the gonadotoxicity of environmental agents and pharmaceutical compounds. Testicular organoids may also serve as natural producers of testosterone for men who lack testicular function due to disease or injury.

Additionally, we are pursuing several different strategies to engineer replacement kidney tissue or restore kidney function. One effort involves bioprinting kidney-like structures. It is based on earlier research in which a hand-engineered “mini kidney” was implanted in a steer and produced urine. The research is still in its early stages.

3. The holy grail of bioprinting is the creation of a solid human organ with vasculature, such as the kidney. How feasible do you think it is?

A major hurdle of bioprinting is ensuring that bioprinted structures have an adequate supply of nutrients and oxygen until they can integrate with the body. Maintaining structural integrity is another challenge.

Using a sophisticated, custom-designed 3D printer, our research team has shown that it is feasible to print living tissue structures to replace injured or diseased tissue in patients. We bioprinted ear, bone and muscle structures that, when implanted in animals, matured into functional tissue and developed a system of blood vessels. The vascularization challenge was solved in two ways. The water-based “ink” that holds the cells was optimized to promote cell health and growth. In addition, a lattice of micro-channels was printed throughout the structures to allow nutrients and oxygen from the body to diffuse into the structures.

There are many challenges to meet for complex structures like the kidney. I do believe that one day there will be some kind of regenerative medicine therapy for patients with end-stage renal failure. I think we can safely say that the timeframe will be decades, rather than a few years, but science can surprise you.

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