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Successful Stem Cell Replacement of Windpipe
thepacketmaster writes "In what is being hailed as a medical milestone, CNN reports a woman suffering from long-term tuberculosis had her lower trachea and bronchial tube replaced by tissue grown from her own stem cells. A team from the universities of Barcelona, Spain; Bristol, England; and Padua and Milan, Italy, decided to go ahead with the surgery instead of having to remove her left lung. The operation, reported Wednesday in the British medical journal The Lancet, has been hailed as a major leap for medicine that could offer new hope for patients suffering from serious illness."
I just feel like I should point this out before someone decides to go on a rant about embryonic SC.
FTA:
While this procedure still does require a donor organ, it basically only uses the donor as a collagen framework to grow the patient's cells into.
Could the next step be fabricating the collagen frame, perhaps through 3D printing?
Your mind is clear / The things that you fear / Will fade with how much you / Believe what you hear
I have been listening to this story being hyped in the news all day, but it doesn't deserve quite that much attention. While this is a "great case" that most surgeons would appreciate, and a great outcome for the patient, the CNN report (and NPR and others) does what lay media generally do with medical reports - over-dramatize yesterday's news. This is an evolutionary case based on established surgical technologies which have been validated over the past 12 years, not a revolutionary implementation of new science. And regardless if you have any thoughts or opinions about embryonic stem cell research, this is not an embryonic case, it is just the use of autogenous cells to repopulate a regenerative biomatrix.
This is the "new surgery" of the 21st century, a move toward live engineering of living tissues rather than using alloplastic implants. Much of this new surgery is done strictly in situ, inserting an implant, and letting pluripotential cells circulating through the host find the implant and then reorganize themselves into a mature tissue. This works well with connective tissue matrices that will support the ingrowth of "connective tissue cells" derived from the embryonic mesoderm. The items available to surgeons are manufactured matrices such as Integra (Integra Life Sciences, New Jersey), and cadaveric matrices, usually dermis (of human, bovine, porcine, and equine origin, eg from LifeCell, Ethicon, TEI Biosciences, et al). Simply put, we implant these materials to reconstruct dermis, fascias, ligaments, and various skeletal and mesenchymal structures, and human host cells find them and make new living dermis-fascia-ligaments-etc. This works extremely well for reconstruction of skin and musculoskeletal structures. Not much progress has been made yet on the generation of glands and organs (which require function specific epithelial or ecto-entodermal cells).
These technologies and procedures have been a part of regular surgical practice since about 1996. Make no mistake about it - the tracheo-bronchial reconstruction you read about is a great case, but it is just a progressive implementation of existing concepts and methods to a wider range of diseases and indications. There will be more and more and more of this is the coming decades. In fact, existing regenerative materials could have easily made a new trachea-like conduit, avoiding the need for a human anatomical gift or organ donation, except for one thing . . .
The trachea and bronchi need a special architecture to avoid collapse. Because of the Bernoulli principle, these conduits could collapse during inspiration, so nature prevents that by having these pipes surrounded by semi-rigid cartilage rings. Regenerated cadaveric dermis by itself will not work. So instead, these guys used a donated trachea for its gross architecture and mechanical integrity, processed it in the same way that dermal matrices are processed to get rid of cells and immunogens, and then they seeded some host cells, then let it grow in situ. In actuality, the seeding step was largely irrelevant. When collagen-aminoglycan matrices (decellularized cadaveric materials) are implanted, circulating stem cells find them automatically. Pre-seeding could speed up the process by a week or so, but no big deal.
The cells which were seeded were NOT embryonic stem cells. They were just autogenous random marrow cells, some of which will be pluripotential, and able to regenerate tissues according to an embryonic model of tissue histogenesis. Note too that even if these were embryonic omnipotent stem cells, there is no such thing as a tracheal cell. What they implanted was a connective tissue matrix, generated by, and then repopulated by two and only two types of cells: fibroblasts and vascular cells. This is the supporting structure of all organs and tissues. Think of it like reinforced concrete. You can use cement and rebar to make a bridge, a road, a building, and so on, all with different shapes, loads, and functions, but it's all just cement and rebar.