Friday April 11 2014
Tissue engineering holds a lot of potential
"Doctors implant lab-grown vagina" is the headline on the BBC News website, reporting on the latest breakthrough in the increasingly exciting field of tissue engineering.
In this latest study, tissue engineering was used to develop a vagina for reconstructive surgery in four teenage girls who had the rare condition Mayer-Rokitansky-Küster-Hauser syndrome. In this condition, the vagina and uterus do not form properly while the female foetus is developing in the uterus.
Various techniques have been used for vaginal reconstruction in the past, usually involving surgically creating a space where the vagina would normally be and lining this with graft tissue. However, there have been problems with the types of graft tissue used, including the muscle not functioning correctly.
In this new technique, tissue samples were taken from the girls' own vulvas and then grown in the laboratory into a 3D structure for reconstruction. Over the course of up to eight years' follow-up, the reconstructed vagina was demonstrated to have a similar structure to normal vaginal tissue and the women reported normal sexual function. There were no adverse effects or complications of surgery reported.
While the problem of Mayer-Rokitansky-Küster-Hauser syndrome may not be a major public health issue (though obviously extremely distressing for those affected by it), this small study does mark an important proof of concept.
The vagina consists of a complex structure of tissue. If a vagina can be reconstructed, it may be possible to reconstruct other complex structures and one day possibly even entire organs.
Where did the story come from?
The study was carried out by researchers from the Tissue Engineering Laboratory, Children's Hospital of México Federico Gómez, Metropolitan Autonomous University, CINVESTAV-IPN in Mexico, and Wake Forest University School of Medicine in the US. Funding was provided by Wake Forest University and the Children's Hospital of México Federico Gómez.
It was published in the peer-reviewed medical journal, The Lancet.
The media reporting of the study was accurate and provided some useful background context. The companion piece in the same journal about reconstructing nostrils failed to gain the same publicity, only being mentioned in The Independent.
What kind of research was this?
This was a case series reporting on a new vaginal reconstructive technique used in four consecutive women with a condition called Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS). In this condition, a female foetus fails to develop the vagina and uterus properly, and these are wholly or partly absent from birth. It is estimated to affect between 1 in 1,500 and 1 in 4,000 female babies.
The girls usually first present to doctors during the early teenage years, when they do not start their periods as expected. If the uterus has formed, there may also be monthly abdominal pain, or a lump that develops in the abdomen because the uterus is still shedding blood monthly but there is no drainage route.
The main treatments are usually surgical and many different techniques have been developed for vaginal reconstruction. These often involve surgically creating a space where the vagina would normally be and lining this with graft tissue.
Various different tissues have been tried for grafts, such as skin or abdominal tissue, though these types of grafts do not contain the normal constituents of vaginal tissue. This can cause problems such as decreased pleasure during sex and narrowing of the space (stenosis).
This study reports the experience of using tissue engineering techniques to create a vagina using girls' or women's own external genital tissue (vulval tissue) rather than donor tissue or tissue from elsewhere in the body.
What did the research involve?
The study involved four consecutive teenage girls (aged 13 to 18 years, average age 16) with no vaginas (vaginal aplasia) as a result of the condition MRKHS. They came to the researchers' hospitals between May 2005 and August 2008.
Three of the girls first came to their doctors because of not having periods and the fourth because of an abdominal lump (mass). One of the girls had already had a failed vaginal reconstruction using intestinal graft tissue.
The researchers took a detailed history from each of the girls, MRI scanned them, and took tissue samples (biopsies) from the vulva to obtain tissue for the graft. They separated the tissue's muscle layer from the epithelial layer (that lines body surfaces) for separate processing.
They then used tissue engineering techniques to develop the vaginal structure for reconstruction using a 3D "scaffold" specifically developed for each girl depending on the dimensions of the pelvic area on MRI and physical examination.
The girls underwent vaginal reconstruction five to six weeks after the initial biopsy samples had been taken. They had vaginal examinations and biopsies three, six and 12 months after surgery, then yearly after that.
All girls also received MRI monitoring and filled in the Female Sexual Function Index questionnaire, a validated self-report tool for assessing female sexual function.
What were the basic results?
All of the girls had the initial vulval biopsy and the vaginal reconstructive surgery without any immediate or postoperative complications. They were followed up for an average of 81 months (6.75 years).
The yearly biopsies showed that the transplanted vaginal tissue had a normal triple-layered structure consisting of an epithelial cell-lined vaginal canal surrounded by matrix and muscle. The MRIs and vaginal examination showed that the tissue-engineered vagina also appeared to be normal.
The two girls who had a partially developed uterus and had the vaginal tissue joined to their uterus went on to have periods.
The Female Sexual Function Index questionnaire showed that the girls reported in the "normal" range for all areas questioned: desire, arousal, lubrication, orgasm, satisfaction, and painless intercourse.
How did the researchers interpret the results?
The researchers concluded that implanted vaginal tissue engineered from the patient's own cells showed normal structure and function over eight years.
They say that this technique could be useful in other patients requiring vaginal reconstruction.
This small case series reports the apparent success of using tissue engineering techniques to develop a vagina for reconstruction in four teenage girls who had an absent vagina from birth. All of these girls had the rare condition Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS), where the vagina and uterus do not develop properly.
The technique used tissue samples biopsied from the girls' own vulva, which were then developed in the laboratory to make a 3D structure for reconstruction. It was hoped that by using this approach they might avoid some of the problems seen with the various types of graft tissue previously used, including abnormal muscle function.
Over up to eight years' follow-up, the reconstructed vaginas did seem to have a similar structure to normal vaginal tissue. The girls and women reported normal sexual function without unexpected adverse effects or complications.
This study only reports on a very small sample of four girls with this condition. Further use of this technique is needed to see if the same successful results are replicated.
With that limitation in mind, this study – as well as the related study about nostril reconstruction – suggests that tissue engineering is an avenue of research with a great deal of potential.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.