As reported by The Hartford Courant, May 8, 2007.

Embryonic Cells 'Remarkable'

Scientists See the Potential to Repair Blood Vessels During Tests on Mice

By William Hathaway

Three blind mice?

Not so fast.

Using cells derived from human embryos, scientists from a Massachusetts biotechnology company say they have repaired damaged retinas in mice, saved other animals who suffered catastrophic heart attacks and restored blood flow in the limbs of mice damaged by blood clots.

"They are really remarkable cells," said Dr. Robert Lanza, senior scientist of Advanced Cell Technology of Worcester and senior author of the study, published Monday in the online edition of the journal Nature Methods. "They have the potential to help in a host of different diseases."

The study is an illustration of the potential of embryonic cells - or in this case, embryonic cells coaxed by scientists to take the first step toward creating blood vessels that could help treat diabetes, heart disease and stroke.

The authors believe the cells used in the studies have several advantages over use of adult stem cells, which are less controversial than embryonic cells but have more limited potential.

The study describes a new method of reproducing an unlimited supply of the cells that form almost immediately after embryonic stem cells take the first step to forming blood and the immune system. The cells, called hemangioblasts, have a remarkable ability to migrate to damaged blood vessels and repair them, the study suggests.

For instance, the study says, the cells began to repair blood vessels damaged by diabetic retinopathy - a leading cause of blindness in people, within two days after being injected into the eyes of mice.

Yet, if no tissue is damaged, the same cells simply congregate on the surface of the eye.

"It is clear that the damaged cells are sending out an SOS saying, `Help, help, over here,'" and the cells respond, Lanza said.

Mortality from heart attacks induced in mice also decreased by half after mice received injections of the cells, the study showed. And after receiving injections of cells, blood flow increased in the limbs of mice with the rodent equivalent of blood clots.

The medical potential of such cell therapy "is huge," said Timothy Hla, professor of vascular biology at the University of Connecticut Health Center.

Diabetics in danger of losing their vision or limbs to amputation would be obvious beneficiaries of such cells, Hla noted.

Lanza said the company hopes to begin trials in humans beginning late next year.

Hla, however, notes that the entire field of regenerating blood vessels is still controversial. Some scientists, for instance, doubt whether stem cells actually form new blood vessels themselves, thinking perhaps they simply fuse with existing cells.

Early trials using adult stem cells from bone marrow, which tend to be more specialized in types of tissue they form, in treating heart disease have been disappointing.

"But whatever [the hemangioblasts] are doing, they do seem to have activity," Hla said.

However, the cells seem to have benefits over both adult and embryonic cells in regenerative medicine, some scientists note.

The cells are taken "much earlier in development [than adult stem cells] and therefore have much higher potential," said Anthony Atala, director of Wake Forest Institute for Regenerative Medicine.