Scientists constructed human tissue using nanowires
The technology could enable better monitoring of replaced tissues and organs
This "cyborg" method could be combined with automated drug delivery mechanism
The day may come when transistors in our bodies help us live.
Scientists are working on a futuristic tissue engineering venture to grow better solutions for damaged or missing organs. They published their findings in the journal Nature Materials this week.
The idea is that you could create tissue or an entire organ, implant it in the body, and keep tabs on inflammation, rejection and other health indicators, said Robert Langer, study co-author and professor at Massachusetts Institute of Technology.
“This is a way to sort of create an organ and at the same time monitor how well it’s doing with biosensors,” Langer said.
Other groups of scientists have been working on growing organs outside the body. In June 2011, a patient received a synthetic windpipe, which had been made using stem cells from the patient and no donor tissue.
Langer’s group is putting a new spin on the organ-growing concept by incorporating silicon nanowires. These wires, with diameters about 1,000 times smaller than the width of a human hair, have a fine electrical sensitivity, capable of detecting less than one-thousandth of a watt of power.
This research is still in its early stages; it’s nowhere near ready for hospitals. The next step is to try it in animals, and eventually humans. The testing will take “several years,” Langer said.
Making a “cyborg” organ in this way involves constructing a polymer scaffold with silicon nanowires embedded. Cells are then “seeded” on the scaffold, similar to how grass grows from seeds.
When placed in a bioreactor, more cells grow on the structure to form the desired tissue or organ. In this study, scientists successfully constructed cardiac, neural and muscle tissue.
With the cardiac tissue, researchers used the sensors to examine the response to the substance noradrenalin, which can speed up heart rate.
Through the sensors, scientists were able monitor pH changes of the blood vessels that they also grew.
With more technology and research, Langer said, the tissues could potentially be wired to release a drug in response to negative events such as inflammation.
This all may sound complicated, but Langer expects that if the technology becomes commonplace in human patients, it would be cheaper than a heart transplant and the long hospital stays associated with those kinds of procedures.
The technology appears to be very promising, said Dr. Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina, who was not involved in the study. Atala has been on the forefront of regenerative tissue engineering, leading a study last year that constructed urethras in five young patients, using the patients’ own cells.
There has been previous research on nanowires and scaffolds, but having nanowires go through the scaffold allows for real-time information about how the engineered tissues and organs are performing, he said.
“One could foresee following the functionality of these organs – it is like having a mini-ICU (intensive care unit) right at the site of the engineered tissue or organ implanted,” Atala said.
Increasingly, three-dimensional cultures are being used for drug screening studies and as models before studies are conducted on animals, noted Ravi Bellamkonda, bioengineering researcher at Georgia Institute of Technology, who was not involved in the new study. The nanowire technology could help scientists monitor cellular response in these sorts of studies, too.
It is not clear, however, whether it’s possible to obtain information from multiple points on the three-dimensional scaffold, or whether the technology could be implemented in implantable scaffolds, Bellamkonda said. The technology hasn’t been tried in animals.
From what scientists know so far, the materials involved in the sensors appear to be safe in the body, Langer said. Langer has also worked on technologies on the nanoscale that attempt to target tumors without the side effects of current cancer drugs.
In February, Langer and colleagues published the results of a clinical trial involving an implanted microchip in the journal Science Translational Medicine.
The programmable implants successfully gave an osteoporosis drug to seven women with no negative side effects. This study was done through the company that Langer co-founded, MicroCHIPS, Inc. This and other research suggests that putting these particular chemical elements in the body is safe.
The “lab on a chip” idea may one day be combined with the nanosensor tissue engineering concept, said study co-author Dr. Daniel Kohane of Harvard University. The chip would respond to the electrical effects from the engineered tissue, administering certain drug dosages accordingly.
But that’s all in the future, for now.