Tag Archives: medicine

Laboratory lungs to replace rats

Got lungs?Briefly overcoming my kneejerk hatred of articles with the phrase “[x]-on-a-chip” in their headline, here’s a New Scientist article about a new development that could eradicate the need for lab rats in toxicology experiments. The basic idea: grow little spheres of lung tissue on a silicon substrate, enabling you to run multiple tests at once.

While the ethics of animal testing are a contributing factor here, there’s also a significant element of practicality:

… the European Union’s REACH regulations require about 30,000 chemicals to be tested for toxicity over the next decade. Yet testing the effects of inhaling a single dose of a particular chemical typically requires more than 200 rats, while testing the chronic effects of breathing it in over time can take more than 3000. Meanwhile the EU Cosmetics Directive – which covers items from deodorants and perfume to air-fresheners – seeks to ban all tests of cosmetics on animals by 2013.

The obvious alternative is to test chemicals on human cells grown in the lab. The difficulty, however, lies in enticing those cells to form complex tissue that responds as our organs do.

That difficulty hasn’t yet been overcome, but this project and others like it suggest that it’s far from insurmountable. Given the collosal advances in computer modelling in recent years, though, I wonder whether these artificial test organs will be in use for long before being superceded by software – which would not only be ethically sound but presumably much faster as well. [image by bbaunach]

New resin for growing flesh

biodegradable_resinResearchers at the University of Twente have developed a biodegradable resin that can be used to create precise replicas of forms within the body around which new tissues can be grown:

The resin can be given different properties depending on where in the body it is to be used. Cells can be sown and cultured on these models, so that the tissues grown are, in fact, produced by the body itself. The new resin has been developed by Ferry Melchels and Prof. Dirk Grijpma of the UT’s Polymer Chemistry and Biomaterials research group. An article on this breakthrough will be appearing in the authoritative specialist journal, Biomaterials

The method used to recreate the specific forms is called stereolithography, the improvement in this system is that the resins have hitherto not been biodegradable. This means:

If, for example, a child has a heart valve disorder, a 3D digital image of the heart valve can be created using a CT scanner. The model in the stereolithograph can be copied exactly with the new resin. If the structure is made porous, the child’s own cells can be placed on it. This porosity also gives nutrients access to the cells. Ultimately, after the carrier structure has broken down, only the natural tissue remains.

Which is a rather wonderful development.

[from Physorg]

Stem-cell contacts restore eyesight

eyeStill wondering whether there’s a down-to-earth application for stem cell science that doesn’t involve tabloid-rousing research ideas like chimeric embryos? Well, get this for a simple, elegant and incredibly useful deployment: wearing contact lenses primed with stem cells can restore eyesight in people with corneal damage.

The idea stemmed from the observation that stem cells from the cornea (the thin, transparent barrier at the front of the eye) stick to contact lenses. Employing three patients who were blind in one eye, the researchers obtained stem cells from their healthy eyes and cultured them in extended wear 1 day acuvue moist for astigmatism for ten days. The surfaces of the patients’ corneas were cleaned and the contact lenses inserted. Within 10 to 14 days the stem cells began to recolonize and repair the cornea.
“The procedure is totally simple and cheap,” said lead author of the study, UNSW’s Dr Nick Di Girolamo. “Unlike other techniques, it requires no foreign human or animal products, only the patient’s own serum, and is completely non-invasive.
Of the three patients, two were legally blind but can now read the big letters on an eye chart, while the third, who could previously read the top few rows of the chart, is now able to pass the vision test for a driver’s license. The research team isn’t getting over excited, still remaining unsure as to whether the correction will remain stable, but the fact that the three test patients have been enjoying restored sight for the last 18 months is definitely encouraging. The simplicity and low cost of the technique also means that it could be carried out in poorer countries.

Brilliant! Now, insert your own joke about George W Bush and myopia here. [image by peasap]

Reaching an accomodation with cancer

cancer cellsIn the Western world at least, cancer is one of our most intractable enemies; medical science has advanced hugely in the last half-century, and cancer mortality rates have fallen as a result of preventative measures, but the essential approach remains the same as it ever has been – eradicate the tumour cells from the body at any cost.

Mathematical oncologist Robert Gatenby reckons that’s the wrong route, though. He suggests that rather than doing our utmost to purge cancer from the body, we should instead seek to reach a form of compromise with it – playing it to a stalemate, in other words, treating it as an inevitability to be controlled rather than an alien incursion to be expelled.

How people treat invasive species can provide an analogy for thinking about cancer therapy. In treating a field for a pest, for example, you might treat three-quarters of it with a pesticide, and leave the other quarter untreated. Pesticide-sensitive pests remain there, and they spread out into the field after treatment, preventing pesticide resistance from becoming dominant.

Using pesticides on an entire field is like what we’re doing with cancer now. And we all agree that we’d rather get rid of the pests altogether, but if you can’t do it, if every time you have an infestation you treat it and get resistance, then you try a different strategy. The alternative is to try to reduce the pest population so that it doesn’t damage your crop, and accept the fact that they’re going to be there. That’s what I’m talking about with cancer.

There’s a certain seductive logic to Gatenby’s idea; it chimes in harmony with the more systemic approaches we’re starting to take to agriculture and the environment, for example. Obviously, there’s a lot of research to be done to check whether or not he’s on to something, but the prospect of higher cancer survival rates using the drugs and treatments we already have to hand is a heartening one. [image by euthman]

Viruses used to kill cancer cells

tamedviruswiA fascinating concept: researchers at the University of Oxford have developed a method that uses modified viruses to destroy cancerous cells, whilst leaving healthy cells intact:

The research team modified a common virus – called an adenovirus – so that it could deliver genetic therapy to destroy tumours without poisoning the liver.

The changes enabled the virus to keeps its natural ‘infectious’ characteristics to replicate in, and kill, cancer cells in mice.

But for the first time the virus is also recognised and destroyed by healthy mouse liver cells, so it is no longer toxic.

Poachers make the best gamekeepers, no?

[from Physorg][image from Physorg]