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Tissue Engineering's Evolving Promise
For thousands of patients waiting for organ transplants,
new innovations can deliver new options
By Molly Aulson

A new field in the early 1990s, tissue engineering applies the principles of biology and engineering to develop solutions to organ or tissue damage. The cross-disciplinary practice emerged in direct response to urgent demand. According to the American Transplant Foundation, since 1988, more than 700,000 patients in the United States have received organ transplants, with a new name being added to the waitlist every ten minutes. In Europe, the Council of Europe estimates 19 patients die every day while waiting for an organ transplant.

The number of organs available definitely do not meet the demand.

— Dr. Riccardo Gottardi

According to Dr. Riccardo Gottardi, bioengineering and biomaterials expert and assistant professor at University of Pennsylvania and Children's Hospital of Philadelphia, "The number of organs available definitely do not meet the demand." Patients are primarily waiting for kidneys, livers, hearts and lungs. Engineering these organs is very complicated, but making tissues to restore and maintain them is simpler — which is why tissue engineering is so important.

The science behind tissue engineering has often been misrepresented in pop culture though, associated with examples like Jurassic Park's genetically engineered dinosaurs or the Vacanti mouse rather than its importance to a prominent health crisis. The realities of tissue engineering have evolved over the last 25 years. In the 1990s, scientists believed they could use mesenchymal stem cells (MSCs) commonly found during embryonic development to regenerate new cells and fix damaged tissue. However, they quickly realized they could achieve better results with more developed cells.

Using adult cells to mimic processes of organ and tissue development instead, scientists decided to hack developmental biology. Consider inflammation: although it can cause several issues in the body, it could assist in tissue regeneration if scientists know how to hack the inflammatory response.

Thus, today's tissue engineering methods were born.

Dr. Riccardo Gottardi discusses the new techniques enabling tissue engineering.

In an important milestone, scientists have already successfully completed a cartilage transplant into a patient's nose. But this level of tissue engineering is only the beginning. Nose cartilage withstands much fewer mechanical aspects than, for example, the cartilage that we walk on, making it simpler to repair. For scientists, figuring out how to fix cartilage we use to walk and run is the next key innovation.

New advances in the fields of biology and 3D printing are furthering this revolutionary potential by addressing the main challenge in making more complex tissues: vascularization. Vascularization requires not only nutrients but also signals, especially during tissue and organ formation. Currently, scientists can place organs and cells in the body and can get muscles like the heart to beat, but it remains difficult to engineer a way to tell the cells where to go and what to do.

Although a challenging feat, the future of tissue engineering still looks encouraging to the thousands of patients in need of transplants. Gottardi hopes that he and other scientists will be able to design tissue environments wherein the cells play an active role in the engineering, delivering more complex solutions.

Tissues engineers also aim to keep cell regeneration in the operating room. The future holds potential for off-the-shelf tissue scaffold platforms — cell support that biodegrades in the body over time — that surgeons can imbibe with cells and implant for repair. Another innovative solution involves bioprinting tissues on-site and using a biopen to directly fix damage without leaving the operating room. All these components are on the horizon and will push the fast-growing field's innovative capabilities to the next level once implemented.

Tissue engineering has gone through quite an evolution since its emergence. Much like the scientific implications of bringing dinosaurs back in the Jurassic Park movie franchise, it has been well-received by the public at times and misunderstood at others. However, as the science continues to evolve and the demand for organ and tissue repair continues to grow, its improvements indicate a promising offer to global patients in need.

As Gottardi said about the future successes of tissue engineering, "It's closer than you think."