Bioengineered blood vessels offer hope for children
Advances in tissue-engineered vascular grafts offer possibilities for treating congenital heart defects.
Children born with complex congenital heart defects have new hope, thanks to the latest generation of autologous, tissue-engineered blood vessels.
Advances in the field could potentially reduce the need for repeated surgeries and change the future of pediatric cardiac care, said Christopher Breuer, MD, a speaker Saturday at the session “Bioengineering Human Tissue and the Future of Vascular Replacement in Congenital Heart Disease.”
During his presentation, “Lessons in Tissue-Engineered Vascular Graft Remodeling in Children With CHD,” Breuer will detail how these advances are bringing researchers closer to creating critical engineered tissues that can grow and remodel with young heart patients.
“The surgical repair of most complex cardiac anomalies requires the use of prosthetic biomaterials in the form of vascular grafts, heart patches or replacement valves. Complications associated with the use of these biomaterials are a significant source of morbidity and mortality in this patient population,” said Breuer, the director of the Center for Regenerative Medicine at Nationwide Children’s Hospital in Columbus, Ohio. “Exclusive use of autologous tissue avoids these complications but is frequently not possible due to the extent of the underlying heart defect.
“Tissue engineering provides a method for creating autologous neotissue, which can be used to repair or replace tissues that are diseased, damaged or congenitally absent.”
Engineered tissues integrate naturally with the body, Breuer said. However, the technology faces scientific and regulatory challenges. To illustrate these challenges, Breuer will focus on a tissue-engineered vascular graft designed for congenital heart surgery, the hurdles of translating the technology from bench to bedside, and strategies to overcome or avoid them.
One of the biggest challenges facing pediatric heart patients, he said, is somatic overgrowth, where a child physically outgrows an implanted graft or valve. Because current prosthetic devices can't grow, Breuer said patients need additional interventions, including surgical replacement or stent expansions, as they age. These “upsizing” procedures can threaten a child’s health and can place a substantial burden on patients and families.
“Surgeons have had to develop strategies to delay surgery or use oversized devices to avoid somatic overgrowth. These strategies are associated with their own risks,” Breuer said. “The development of vascular grafts or replacement heart valves with growth capacity could avoid these complications and improve outcomes.
The key advantage of these autologous grafts, however, is their ability to integrate into the body.
“By creating neotissue from a patient’s own cells, we can avoid the risk of rejection. Additionally, the autologous neotissue can use the body’s own mechanisms to repair, remodel and grow, thus improving durability and performance,” he said.
Breuer said the advancement of the technology depends on close collaboration among scientists, clinicians and regulators to ensure the safe, efficient development of regenerative medicine technologies.
Several factors, he said, can facilitate that progress:
- Understanding the cellular and molecular mechanisms underlying neotissue formation.
- Developing metrics specific to tissue-engineered devices to describe differences in graft performance.
- And investigating how the new devices affect late-term complications in cases where current vascular grafts and replacement valves are particularly problematic.
