I'd hate to sound as if I was brought up on an entertainment diet of Hollywood movies, but back in the 1970's to 80's there was a real revolution in cinematic production and audience interest that led to a cult following of the science fiction genre.
Film directors often take what's probable in science and stretch them to the limits of our imagination, engaging us to just reflect on not only how far we've come but also how much further we can aspire. This next entry is a tribute to the 1987 movie "Inner Space"*.
In a recent announcement, MIT's bioengineers have designed an implantable device that is capable of capturing pure samples of stem cells from the circulating blood. The device is described as "a length of plastic tubing coated with proteins" which has been experimentally implanted into the bloodstream of rats.
The more accurate medical description of this plastic tubing is known as a "shunt" and the method of implantation would most likely involve the severance and reconnection of a small but high through-flow blood vessel. The proteins -known as selectins- attract and trap specific cells with the right signals on the surface (imagine a sticky mat). The cell capture devices are developed by chemical engineers led by Associate Professor Michael King from the Biomedical Engineering department at the University of Rochester. The technical details will be described in the March edition of the British Journal of Hematology.
(personal note: Mr. B.C. this is for you.)
WHY IS THIS DEVICE IMPORTANT?
The medical impact of this device could weigh in for cancer patients who may need to use autologous (one's own) stem cells for their treatment. These cancer patients are treated with chemotherapy to reduce and eliminate as many of the malignant circulating cancer cells as possible from the bloodstream and bone marrow. The treating doctor will collect the patient's own stem cells during this period of remission when the cancer load is at its lowest.
The patient's own stem cells are stimulated using GCSF (read about it here) and the stem cells are harvested and stored in anticipation of the possibility that the cancer cells will multiply again, requiring another round of chemotherapy which may damage the existing healthy marrow further. The collected stem cells will be infused back to the patient to ensure that the patient has sufficient stem cells to repopulate and replenish the marrow, thereby restoring normal cell levels to the bloodstream.
To address the concern that perhaps cancer cells from the patient might also be collected in the same fraction as the healthy stem cells (impossible to distinguish during harvesting) this device could lend a hand to filter out the cancer cells inside or out of the patient's body, i.e. the cancer cells would travel around the bloodstream until they reach the shunt, where they would then be immobilized.
Note though, that the inventors have conceded that this device will not be able to collect enough stem cells for a transplant, therefore the customary stem cell collection procedures will still need to be performed.
SOME INTERESTING STATISTICS
According the A/Prof. King, the shunt placed in an non-GCSF induced rat in a 2 hour period enabled the capture of 3-4 times the number of usual stem cells obtained in normal circulating bloodstream (approx 1%). Hence the device is thought to attract and specifically retain a significantly higher number of stem cells.
This stem cell number could be significantly higher in patients who have been mobilized.
WHAT ELSE CAN IT DO?
Well, it is a concept device which will be as good as its selectin coating. A/Prof. King has already forecasted the use of the device in trapping specific cancer cells in the body to prevent metastatic spread and layering in proteins which could help steer cell development processes by differentiating them while passing through the shunt. (analogy: think sticky mats for dust, sticky mats for cockroaches, sticky mats for cat fur...all requiring different levels of stickiness for its target)
WHEN CAN I BUY IT?
The entrepreneurial A/Prof. King has already started a company by the name of CellTraffix and the anti-metastasis implants are set for animal trials later this year in collaboration with bioengineers Professor Jeffrey Karp and Robert Langer at Harvard and MIT who will develop stable selectin coatings that will last over months than days. Meanwhile, the CEO of CellTraffix, Tom Fitzgerald has already announced that the company's first product for researchers to capture stem cells or cancer cells for lab experimentation will be marketed by early 2009, with clinical testing of the anti-cancer coatings in 2010.
Read how a chance encounter between a bioengineer and a haematology clinician gave rise to this work and watch the cells being captured here (note that you will need a high speed broadband connection as the video files are rather large).
*Why does this remind me of the movie Inner Space I hear you ask... well the term cell capturing device often conjurs up the image of a little machine (like the exploration submersible the protaganist uses) to grab and hold onto cells in circulation :)
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