The term "tissue engineering" refers to methods that promote the regrowth of cells lost to trauma or disease. Tissue engineers use many methods, including the manipulation of artificial and natural materials that provide structure and biochemical instructions to young cells as they grow into specific kinds of tissue. These materials are called scaffolds because they provide support and materials for tissue regrowth in the same way that a scaffold supports workers and materials for a building under construction.
The ideal scaffold delivers just the right amount of support and chemical cues and is harmlessly broken down by the body as new tissue replaces it. The McGowan Institute is a pioneer in the development of scaffold materials, some of which are in clinical use worldwide.
Esophagus and Trachea Reconstruction
If a patient's food tube or airway is damaged, scar tissue can form, which makes breathing or swallowing impossible. Currently, there are no treatments for these conditions other than to remove the damaged areas. McGowan Institute researchers—led by Stephen Badylak, DVM, PhD, MD—are working on a method that uses natural scaffolds seeded with the patient's own cells to encourage the growth of healthy tissue instead of scar tissue. In early studies, a damaged section of the food tube was replaced with a specially formed scaffold constructed from a material already being used in humans. Within 90 days, the scaffold was replaced with functional tissue.
Cells in the peripheral nervous system can regrow, but they sometimes have trouble linking up with each other, which is essential to restore feeling and function. To aid peripheral nerve regeneration, McGowan Institute faculty member Kacey Marra, PhD, and researchers have developed scaffolds made of FDA-approved biodegradable polymers and protein beads. Channels in the scaffolds act as guides for axons, the long arms of nerve cells, to grow longer and in the right directions. In early studies, a nerve guide seeded with stem cells derived from fat restored some hind leg mobility to paralyzed rats.
Muscle Tissue Regeneration
The reconstruction of skeletal muscle tissue either lost by traumatic injury, tumor ablation, or due to congenital abnormalities is hampered by the lack of availability of functional substitutes to this native tissue. Initial studies have focused on the use of small intestinal submucosa scaffolds to replace partial lost gastrocnemius muscle and Achilles tendon. These studies have shown that this material is capable of stimulating restoration of significant muscle mass and restitution of the musclulotendinous junction restoring functionality to a damaged limb. This new muscle growth is both contractile and innervated and comprises a mixed muscle fiber population similar to the native muscle that was lost. Research in this area is conducted by McGowan Institute affiliated faculty members Stephen Badylak, DVM, PhD, MD, J. Peter Rubin, MD, Fabrisia Ambrosio, PhD, Neill Turner, PhD, and Michael Boninger, MD.
Orthopaedic Injury Repairs
Orthopaedic injuries can compromise mobility and hinder quality of life, and not just for professional athletes. At the McGowan Institute for Regenerative Medicine, we've been studying the forces on bones and joints for a long time. We’ve been working on:
- Better ways to help heal orthopaedic injuries
- Better artificial joints
- Replacement tissue for cartilage and ligaments
Much of what we've learned, through the efforts of McGowan Institute affiliated faculty members Prashant Kumta, PhD
, MaCalus Hogan, MD
, Juan Tabaos, PhD
, Alejandro Almarza, PhD
, and Rocky Tuan, PhD
, has already improved surgical and rehabilitation techniques for orthopaedic injuries.
Whole Organ Engineering
Organ engineering, as opposed to tissue engineering, poses significant challenges including the requirement for an immediately functional vascular network, functional parenchymal cells, and lymphatic and innervation potential. In recent years a promising approach for functional organ replacement has emerged: the decellularization of whole organs, providing an acellular three-dimensional scaffold composed of extracellular matrix (ECM). Importantly, the scaffold has been shown to retain the native vascular network of the organ. The long-term goal of this work is to establish the decellularization, recellularization with autologous cells (thus avoiding the need for subsequent immunosuppression), and transplantation criteria necessary to produce functional bioengineered organs for clinical translation. McGowan Institute researchers in the Badylak lab specifically focus on whole liver and heart regeneration.