Researchers have successfully engineered human tissue from autologous tissue for the reconstruction of nasal alar lobules in one first-in-human trial while investigators in separate study were able to engineer and implant vaginas in young women with congenital aplagia.
The results move human tissue engineering closer to one day becoming mainstream health care, according to an editorial accompanying the two studies published in the Lancet.
© Ivan Martin
Currently, for this kind of reconstruction, grafts are made using cartilage excised from the nasal septum, ear, or rib.
"Progression from first-in-human experiences in only a few patients ... to a full integration into health systems involves many steps, and is often an uphill struggle," according to Dr. Martin A. Birchall, professor of laryngology at University College London, and Alexander M. Seifalian, Ph.D., professor of nanotechnology and regenerative medicine at the same institution, in an editorial on both studies (Lancet 2014 April 11 [doi: 10.1016/S0140-6736(14)60533-X]). However, because the human tissue engineering field is not unique in its need for larger trials and long-term follow-up to show efficacy in larger patient cohorts, further progress might be facilitated by the fact that "many countries now have large translational income streams, engaged biotech companies, and streamlined regulatory processes that might lower these barriers."
The two studies achieve three important milestones in the field of human tissue engineering, according to Dr. Birchall and Dr. Seifalian. They provide evidence that when biological scaffolds with or without cells are placed in the body, native tissue will grow in its place rather than scar tissue. And this can be achieved in pediatric populations.
The third – and possibly most important – milestone is that implanting large-scale engineered tissue is possible, since in situ angiogenesis was found to be adequate in the vaginal vaults constructed and implanted in the second study, wrote Dr. Birchall and Dr. Seifalian. The findings help to "edge tissue engineering towards the mainstream of organ and tissue replacement needs," they said.
For the nasal reconstruction study, researchers used nasal septum cartilage cells from each of the five study participants to grow and shape cartilage grafts, which were then implanted in the respective patients whose alar lobule had been badly damaged by treatment for nonmelanoma skin cancer, according to Dr. Ilario Fulco and his associates in the departments of surgery and regenerative medicine at the University of Basel in Switzerland (Lancet 2014 April 11 [doi: 10.1016/S0140-6736(14)60544-4]).
Growth factor was used to expand the cells over the course of 2 weeks before they were seeded onto collagen membranes and cultured for another 2 weeks, until they grew into cartilage that was 40 times larger than the original biopsy. The cartilage was then shaped to fit the defect and was implanted.
At 1-year follow-up, all five reconstruction recipients reported they were satisfied with their ability to breathe, were happy with the look of their nose, and had not experienced any relevant adverse events.
"The engineered cartilage had clinical results comparable to the gold standard cartilage graft surgery," said Dr. Fulco. "This new technique could help the body accept the new tissue more easily, and improve the stability and functionality of the nostril."
Wake Forest Institute for Regenerative Medicine
The results mean that this method is a "viable" alternative to current vaginal reconstructive techniques.
Currently, for this kind of reconstruction, grafts are made using cartilage excised from the nasal septum, ear, or rib, which is painful and requires additional surgery, often fraught with complications.
The second study dealt with four female patients, who had congenital vaginal aplagia. The investigators fashioned vaginal vaults from smooth muscle and vaginal epithelial cells taken from the patients’ own vulvar tissues and grown on vagina-shaped biodegradable scaffolds. The engineered vaults then were transplanted into each of the young women, who were aged 13-18 years at the time of surgery, according to Dr. Atlántida M. Raya-Rivera, a professor of bioengineering at the Metropolitan Autonomous University, Mexico City, and her associates.
At 8 years’ follow-up, all the vaginas were determined to be structurally and functionally normal. At that time, all four women reported that they were sexually active; were satisfied with their desire, arousal, lubrication, and orgasm; and did not experience pain during intercourse.
"Yearly tissue biopsy samples show that the reconstructed tissue is histologically and functionally similar to normal vaginal tissue," noted Dr. Raya-Rivera. The results mean that this method is a "viable" alternative to current vaginal reconstructive techniques because it requires only a small tissue sample and can help avoid the complications inherent when using nonvaginal tissue such as from the large intestine or skin; the complications include infections or grafts that shrink, she noted (Lancet 2014 April 11 [doi: 10.1016/S0140-6736(14)60542-0]).