• Human arteries have been grown from scratch in the lab. Of practical benefit in its own right, this development further opens the door to the production of lab-grown whole organs.
• A 3-D printer is being used to build replacement arm bones for patients, right on the spot in the operating room.
• Superstrong conductive nanowires might one day wind up in artificial muscle for prostheses.
• A bioartificial kidney cartridge (that could be developed into an implant) has had some success in early trials, and could be on the market — perhaps alongside bioartificial livers — in three years.

Growing Organs

Human arteries have been grown from scratch in the lab, and the technique could produce spare blood vessels for bypass surgery, and lab-reared arteries could even connect kidney patients to dialysis machines. First ordinary human muscle cells are encouraged to multiply, then a gene called hTERT is added to make them live longer, and then they seed the cells on a hose-shaped scaffold of biodegradable polymer. After two months, the supports dissolve, leaving a “dense, muscular, tubular structure”.

Reference: Pilcher, Helen R. (2003). “Human Arteries Grown From Scratch.” Nature, June 6 (citing McKee, J. A. et al. Human arteries engineered in vitro. EMBO reports, 4, 633 – 638, 2003.)

The Thigh Bone’s Connected to the USB Port

A Navy contractor has invented a system that converts a CAT or MRI image of an intact arm bone into a 3-D image which is then sent to a 3-D printer* that makes a duplicate bone from porous calcium phosphate-coated polymer. For a patient with a severely crushed or cancer-ravaged arm or leg, a polymer duplicate of their remaining good bone can be surgically implanted to replace the damaged bone. If both limbs are crushed, the system can interpolate and generate a 3D computer model of the missing section instead.

The calcium phosphate coating allows cells from the surrounding real bone to attach themselves to the implant after about 8 weeks. “Then, the real bone begins to ‘grow through’ the porous scaffold,” said its inventor. “As it does, it ‘eats’ the scaffold,” and the body naturally excretes the calcium phosphate and polymer material. It would only take about an hour-and-a-half to create a major bone segment, right on the spot in the OR. The process is expected to take about 18 months in humans for the artificial bone to be completely replaced by natural bone.”

The approach is not entirely new, and a similar technique is already occasionally used by surgeons, but not for load-bearing bones. The new procedure, which involves newer material and a better 3-D printer, has worked in animal experiments.

* Another article on 3-D printers is in the July issue of Health Futures Digest.

See also “Plastics, 3-D Printers, Transparent Displays,” in the Devices section fo the present issue.References: Office of Naval Research (2003). “The Plasti-Bone: A Ceramic Polymer Innovation in Medicine.” ONR Media, June 13; Graham-Rowe, Duncan (2003). “Bad breaks fixed fast by bone ‘printer’.” New Scientist, June 20.

Nanowire

Spider silk is five times tougher than steel, but scientists have now produced 100-meter long carbon nanotube fibers four times tougher than spider silk. The nanotubes also have useful electrical properties, and the researchers succeeded in forming supercapacitors, which store energy, by coating them with an electrolyte. Antenna, batteries, and electromagnetic shields are future possibilities for the material, which could be manufactured in small volumes within a year.

Such material could also presumably find application in superstrong artificial muscle and other replacement body parts.

Reference: Unknown (2003). “Practical Nanotube Fiber Near.” Technology Research News, June 17 (citing the June 12, 2003 issue of Nature Materials.)

Cyborgans

Six of ten critically ill patients in a phase I clinical trial survived thanks to an experimental “bioartificial kidney” cartridge made of 4,000 hollow, plastic fibers containing a billion live, human kidney cells. Dialysis can cleanse blood, but it cannot perform the subtle metabolic functions of the kidney. The new device can, and it could be on the market in three years. For the 400,000 Americans with chronic kidney disease who must undergo almost daily dialysis — many of them unable to obtain or to endure a kidney transplant – the device could save lives, prevent heart disease and infection, and improve the quality of life.

The phase I test only lasted 24 hours, yet it not only showed that the device was safe but also that it brought some of the patients out of acute kidney failure. A similar technique is being used to create other bioartificial organs, including a bioartificial liver also undergoing advanced clinical trials. Plaguing the development of implantable bioartificial organs has been the inability to protect cells from patients’ immune systems. The porous plastic fibers in current bioartificial kidneys and livers protect the cells from immune system attack but not from antibodies which, over time, destroy the cells. Nano-materials under development could overcome this problem.

Reference: Fairley, Peter (2003). “Saving Lives with Living Machines.” Technology Review, July/August.