Although stem cells from umbilical cord blood have been harvested for some time, the researchers discovered that the cord tissue itself also is rich in stem cells. Early experiments with mice found that mesenchymal stem cells could stimulate growth of bone and cartilage and accelerate healing of skin wounds. Other potential uses include regenerative medicine for spinal cord injuries or damaged hearts, and treatment of autoimmune diseases.
For fetuses, the umbilical cord is a lifeline. Once those babies are out of the womb, however, the cord becomes so much medical waste, tossed out even if the cord blood is saved for future use. But now a group of Toronto researchers says it has discovered that umbilical cords are a "virtually inexhaustible" source of promising stem cells, helping scientists avoid the ethical minefield around cells retrieved from human embryos. The mesenchymal stem cells (MSCs) -- normally isolated from bone marrow or fat -- also proved to be relatively easy to manipulate, a hopeful sign for their possible healing properties, said the team based at Princess Margaret Hospital and the University of Toronto.
Early experiments in the test tube and live mice found that MSCs could stimulate growth of bone and cartilage and accelerate healing of skin wounds, the researchers reported in a paper to be published today in the journalPloS-ONE. Although much work is still to be done, stem cells from umbilical cords might eventually be used to repair hearts after heart attacks or fix broken spines, said Dr. Armand Keating, director of the hospital's cell therapy program and a co-author of the paper. "This is certainly an important step," he said in an interview. MSCs also have a unique ability among stem cells to suppress the body's immune response, suggesting they could have potential in treating auto-immune diseases such as lupus or rheumatoid arthritis, Dr. Keating said.
"The significance of this discovery is huge," Dr. John Davies of the U of T's Institute of Biomaterials and Biomedical Engineering, the lead researcher, said in a statement. Stem cells are non-specific cells that have the ability to replicate and differentiate into other types of cells. Scientists are harnessing them for "regenerative" medicine, helping repair or rebuild damaged or diseased parts of the body. Scientists had seen potential in MSCs but had been largely unable to establish definitively that they had the properties of stem cells. Methods for isolating them were also inefficient, as they had to be extracted from the bone marrow of human donors or, more recently, from fat removed in liposuction, Dr. Keating said. Different, blood stem cells have long been obtained from cord blood, which is "milked" from the umbilical tube and stored by increasing numbers of parents in blood banks for possible future use. The cord itself is discarded. Dr. John Davies and other colleagues at Princess Margaret, though, theorized that the cord tissue contained stem cells, noting that it was an unusual structure that grew from nothing to 55 centimetres in just nine months.
As it turns out, they contain relatively plentiful volumes of the cells around blood vessels and, the researchers note, the 130 million babies born worldwide every year provide an almost limitless supply of used umbilical cords. They seem to have some advantages over embryonic stem cells -- considered the most promising now. The MSCs appear easier to manipulate into other types of cells and circumvent the ethical debate over extracting stem cells from embryos created for in vitro fertilization, a process that kills them. The discovery comes months after researchers at Mount Sinai Hospital in Toronto announced they had found a way to convert skin cells into stem cells without the potentially dangerous side effects of previous methods, considered a major breakthrough. At a recent international conference, the perception was that "Toronto is one of the hotbeds of stem-cell research," Dr. Keating said.