Tuesday, October 23, 2012

Growing nasal cartilage in the lab: Engineering of autologous septal cartilage

Well the possibility for those who need extra nasal cartilage in the nose for aesthetic or functional reasons but don't have enough existing nose cartilage, may soon have another option. On a previous post titled, "Regenerative medicine:Re-growing body parts" August 28 2010 I posted a video discussing in particular how a man was able to regrow his finger using a powder, and it discusses tissue engineering in general, however not for nose in particular.  For those that haven't yet read my previous posts; harvesting cartilage from your own body is preferred method of choice for replacing, or strengthening  missing  or weakened cartilage in the nose. For the nose, the gold standard is nasal cartilage from the quadrilateral region of the septum. When there isn't enough remaining cartilage there because of previous surgical removal the surgeon can harvest cartilage or bone from, ribs, ears, cranium, or hips. Other sources can be from cadaver, or use of synthetic materials. All these are inferior choices to your own nasal cartilage and have their own unique set of drawbacks.  However if cells from your nasal cartilage can be isolated and grown in a lab, to grow new cartilage then that would be the ideal. This research has been underway for couple years now at UC San Diego! 

"Researchers at UC San Diego have turned to tissue engineering to develop replacement cartilage for the nose. Dr. Deborah Watson says a small amount of cartilage is removed from the patient’s nose. Technicians isolate the cells from the tissue, then grow the cells to increase their number. The cells are then placed into a three-dimensional matrix, where they will continue to grow in number and form tissue. Enzymes and growth factors are added to encourage growth and formation of a harder tissue.
Watson says it can take two to three months to generate cartilage that is strong enough to place back in the body. The surgeon will fine tune the shape of the cartilage before inserting it back into the nose. The “new” cartilage is either placed inside a pocket of soft tissue or sutured to remaining cartilage in the nose. Once in place, the engineered cartilage will continue to mature and become stronger.
Cartilage tissue engineering is still in testing phases and not yet approved by the FDA. Watson says the process may eventually enable doctors to provide patients who need nasal reconstruction with an aesthetically pleasing and functional nose. Since the cells come from the patient’s own body, theoretically, there is no risk of rejection of the engineered cartilage."



I really hope that researchers will soon conduct tissue engineering of the turbinates as well, for those who suffer from Empty Nose Syndrome. Except for parts of the sexual organs, which is not an option as donor site, there really is no other part of the human body that acts like or resembles the natural vascularness of the turbinates to be used for replacing lost tissue due to over resectioning.  


Monday, October 22, 2012

Is there a point where it makes more sense to replace & rebuild the entire alar (lower) nasal cartilage?

At one of my nose revision consults, a well known facial plastic surgeon commented to me how he has removed many grafts from patients noses, because they were over-grafted, leaving the nose  too bulky & esthetically unpleasing. He also said he has a rule that when more then 50% of the cartilage is missing (normally due to excessive removal from previous surgery) he decides to replace the whole thing, which although is more time consuming and requires more precise measuring results in a much more natural looking and functional nose compared to adding a variety of different sized grafts to the existing residual nose cartilage throughout the nose. I assume that if the remaining cartilage is of poor quality  or too small it would be comparable to a weak foundation therefore affecting the stability & position of newly grafted cartilage anchored and extending from it. He had shown me before/after pictures of such cases and there was no question the results of his work was an improvement.

Since no other surgeon ever mentioned this to me I began to search online to see if this rule has been documented by other surgeons. While, I didn't find anything that specifically mentions this rule in regards to lower or upper cartilage of the nose, I did find this rule has been applied to when more then 50% of  a subunit of the nose is missing. Here is what i was able to find.

 "In modern times, the practice of reconstruction has been advanced by the work of surgeons such as Burget and Menick,' who proposed the subunit principle of nasal reconstruction. They found that changes in soft tissue and bony contours of the nose resulted in distinct, consistent nasal subunits, including the dorsum, tip, columella, 2 lateral side walls, 2 alae, and 2 soft tissue triangles! These authors found that if greater than 50% of an aesthetic subunit of the nose were missing, it was better to resect the rest of the subunit and reconstruct it in its entirety."

"In 1985, they published the first in a series of articles applying the subunit concept to nasal reconstruction.' In patients with 50% or greater subunit losses, these authors performed esthetically superior reconstruction by removing the remaining portion of the subunit and reconstructing the entire subunit with a skin graft or flap. Burget and Menick later supported the prin­ciple of subunit nasal reconstruction and emphasized that like tissue should be replaced by like tissue."

In regards to specifically  replacing the entire alar cartilage (lower nasal cartilage) the only thing that I was able to find was something I had discussed a long while ago in my post on 'The mystery of all those different nose grafts (Oct 18,2010)" which was the seagull wing graft. However the criteria for determining the decision to replace the alar cartilage with this replacement graft seems to be determined differently then the 50% rule, but not necessarily since the author doesn't mention what amount constitutes "severe signs of overresection...". He states: "The seagull wing technique is indicated in cases in which there are severe signs of overresection of the lower lateral cartilages. Usually, it is recommended for patients who present with a variety of aesthetic and functional complaints, eg, insufficiency of the external nasal valve, alar pinch, or an an intraoperative diagnosis of overresected lower lateral cartilages. In most cases, these indications are associated with poor tip definition and projection and alar retraction. The technique can also be used to lengthen an overrotated and short nose."

Since the nasal tip subunit consists of the alar lower cartilage, perhaps this is why that surgeon i had seen applies the 50% rule.

If any surgeon reading this blog has more knowledge to add to this subject please feel free to contact me or leave a comment. 


Update: Dec 21, 2012

another link to view