Significant strides are being made toward growing replacement organs in the lab, and in substantially repairing badly damaged ones in situ including injecting muscle and pacemaker cardiomyocites grown from embryonic — and potentially even adult — stem cells.

Growing Replacement Organs

Growing entire organs in the lab requires scaffolding for the cells to grow on and a circulatory system to transport oxygen and nutrients around the scaffolding to nourish them. A research team has created a prototype of such a system by computer-generating fractal patterns, etching the patterns onto silicon wafers to form a mold, and using the mold to make microfluidic channels from biodegradable, biocompatible polymers, then stacking the channels to create a three-dimensional scaffold. Endothelial cells were attached to the inside of the scaffolding nanotubes and either liver or kidney cells were attached to the outside. The nanotubes biodegrade, leaving a living scaffolding similar to a natural vascular network.

Early versions implanted into rats for two weeks showed 95 percent survival of the cells. By stacking more and more layers, the researchers hope within ten to 15 years to be able to replace whole human organs.

But there may be more than one way to crack the nut of growing replacement organs. The hospital we criticized last month for using a robot to crack a nut of a different kind seems to have found a way to re-grow healthy bladders or kidneys in patients with terminally diseased organs. Cross-sections of the diseased organ are obtained via biopsy to yield muscle and epithelial cells, which are then nourished and multiplied on a tissue plate for a month while an artificial collagen scaffold is prepared using CT scans of the patient. The healthy muscle and epithelial cells are layered on the collagen scaffolding, incubated for a week, and finally transplanted into the patient. FDA approval has been sought to use the procedure on patients.

Not least, the recent discovery of the enzyme that appears to trigger muscle regeneration in zebra fish, enabling it to re-grow a damaged spine, retina, or heart, could provide a complementary or even an alternative way to crack the nut.

References: Unknown (2003). “Nanotechnology may create new organs.” New Scientist, July 8; Unknown (2003). “Fractals Support Growing Organs.” Technology Research News, July 22; Koerner, Brendan I. (2003). “8 Super Powers: Forget Science Fiction. Here’s the Science.” Wired, Issue 11.08, August.

Stem Cell Therapy for Hearts

University of Wisconsin researchers have found evidence that human embryonic stem cells can grow into three types of cardiomyocytes that make up the heart’s chambers and pacemaker cells. In five to ten years time, injections of specific cardiomyocytes grown from embryonic stem cells might be used to repair damaged heart muscle or replace mechanical pacemakers.

Adult stem cells harvested from patients’ own bone marrow or muscle tissue have been used in trials as replacement cells in congestive heart failure patients, and shown encouraging results. If the success with adult stem cells continues, then embryonic cells may not be needed, and a major ethical dilemma and legal roadblock may be avoided.

Reference: Fauber, John (2003). “Stem cells grow into beating heart cells.” Milwaukee Journal Sentinel, June 27.