New Worlds: Copying the long-lived naked mole rat

Suppose you could replace “Made in China” with “Made in my garage”? Michigan Technological University’s Joshua Pearce is working on it.

By JUDY SIEGEL-ITZKOVICH
Health370 (photo credit: Courtesy)
Health370
(photo credit: Courtesy)
Mice and rats have long since been a standard animal model for cancer research, mainly due to their short lifespans (four years on average) and high incidence of cancer. Naked mole rats, however, are a mystery among mammals. This tiny African subterranean rodent, which is very social, can live for over 30 years and, most surprisingly, is cancer-resistant.
The fact that so far, not a single incident of cancer has been detected in one of these animals makes the naked mole rat an attractive model for finding novel ways to fight cancer.
Recently, a joint team of researchers frin University of Rochester in New York and the University of Haifa discovered that when secreted from the naked mole rat’s cells, high-molecular-mass Hyaluronan (HMM-HA) prevents cells from overcrowding and forming tumors.
“Contact inhibition, a powerful anti-cancer mechanism that arrests cell growth when cells come into contact with each other, is lost in cancer cells”, explains Prof. Eviatar Nevo, from the University of Haifa’s institute of evolution.
“The experiments showed that when HMM-HA was removed from naked mole rat cells, they became susceptible to tumors and lost their contact inhibition.”
HMM-HA is a form of Hyaluronan, a long sugar polymer, naturally present as a lubricant in the extracellular matrix of the human body. It is commonly used in the treatment of arthritis or in anti-wrinkle skin-care products.
According to the current results, the naked mole rat cells secrete extremely high-molecular mass HA, over five times larger than human or mouse HA.
Remarkably, explains Nevo, “the cells of the Israeli solitary blind mole rat, Spalax, which is phylogenetically closer to mice and rats than to naked mole rats, also secreted HMM-HA. This highlights a parallel evolution in unrelated subterranean mammals, presumably a shared adaptation to life underground.”
The researchers speculate that naked mole rats evolved higher concentrations of HA in the skin to provide the skin elasticity needed for life in underground tunnels.
So far, experiments in human cells have been very limited.
However, there has been some evidence showing there is reason for hope. In one of their experiments, the researchers noticed that when naked mole rat HAS2 synthesis protein was overexpressed in human cell tissues, the cells began secreting HMM-HA. This opens new avenues for cancer prevention and life extension in human medicine.
TURNING TRASH INTO CASH
Suppose you could replace “Made in China” with “Made in my garage”? Michigan Technological University’s Joshua Pearce is working on it. His main tool is opensource 3D printing, which he uses to save thousands of dollars by making everything from his lab equipment to his safety razor.
Using free software downloaded from sites like Thingiverse, which now holds over 54,000 open-source designs, 3D printers make all manner of objects by laying down thin layers of plastic in a specific pattern. While high-end printers can be very expensive, simpler opensource units run between $250 and $500 – and can be used to make parts for other 3D printers, driving the cost down ever further.
“One impediment to even more widespread use has been the cost of filament,” says Pearce, an associate professor of materials science and engineering and electrical and computer engineering.
Though vastly less expensive than most manufactured products, the plastic filament that 3D printers transform into useful objects isn’t free. Milk jugs, on the other hand, are a costly nuisance, either to recycle or to bury in a landfill. But if you could turn them into plastic filament, Pearce reasoned, you could solve the disposal problem and drive down the cost of 3D printing even more.
So Pearce and his research group decided to make their own recycling unit, or RecycleBot. They cut the labels off milk jugs, washed the plastic and shredded it.
Then they ran it through a homemade device that melts and extrudes it into a long, spaghetti-like string of plastic.
Their process is open-source and free for everyone to make and use at Thingiverse.com.
The process isn’t perfect. Milk jugs are made of highdensity polyethylene, or HDPE, which is not ideal for 3D printing. “HDPE is a little more challenging to print with,” Pearce says. But the disadvantages are not overwhelming.
His group made its own climate-controlled chamber using a small refrigerator and an off-the-shelf humidifier and had good results. With more experimentation, the results would be even better, he says. “3D printing is [today] where computers were in the 1970s.”
RecycleBots and 3D printers have all kinds of applications, but they would be especially useful in areas where shopping malls are few and far between, Pearce believes. “Three billion people live in rural areas that have lots of plastic junk,” he says. “They could use it to make useful consumer goods for themselves. Or imagine people living by a landfill in Brazil, recycling plastic and making useful products or even just ‘fair trade filament’ to sell.
Twenty milk jugs gets you about one kilogram of plastic filament, which currently costs $30 to $50 online.”