News: Using stem cells to grow organs organically

Australian scientists believe it may be possible to grow replacement organs organically, by providing organ-building stem cells with a 3D template and leaving them to grow in situ, within the patient’s own body.

In a collaborative research project, Monash University and University of Queensland researchers have successfully grown arteries, ureters and pieces of bladder tissue on polymer templates placed inside the peritoneal cavity of laboratory animals, close to the bowel.

Prof John Bertram, head of anatomy and cell biology at Monash University, says that stem cells will grow around any object inserted into the peritoneal cavity that replicates the shape of the desired organ. The size and shape of the organ can be controlled by modifying the template.

Bertram’s colleague, research fellow Dr Sharon Ricardo, says mesothelial cells from the large bowel colonise the template, forming a biological coating. Similar results have been obtained with blood clots introduced into the peritoneal cavity.

"The cells form a tube, in any shape you want," she said. "You then remove the tube, turn it inside out and engraft the new implant into a normal blood vessel. Three months later it is indistinguishable from the original blood vessel”"

Ricardo is working with Dr Melissa Little, who received a large grant from the National Institutes of Health in the US to investigate whether it might be possible to grow new kidneys from progenitor stem cells.

"My part of the project is to determine whether the adult kidney contains a population of kidney progenitor cells, and whether the right environment may induce them to form specialized kidney cells," Ricardo said.

Ricardo says she is also investigating whether haemopoietic stem cells originating in bone marrow have a role in organ repair and organogenesis.

She has experimental evidence that stem cells injected into the bone marrow of mice suffering from kidney failure migrate to the kidneys and form new kidney cells to repair the damaged organ.

"I’m also trying to determine if blood-borne stem cells enter other organs such as the heart, lung and liver, to replace damaged cells.

"There is evidence that haemopoietic stem cells don’t just form blood and immune-system cells. They may be pluripotent, and capable of forming other major organs."

Ricardo says clinical experiments in patents with heart disease have indicated that stem cells introduced into the coronary artery improve heart function.

"If stem cells are coming in through the blood, or there is a left-over population of stem cells an organ like the kidney after embryonic development, they may just be awaiting the right inflammatory cues to differentiate into renal cells."

Ricardo is comparing diseased adult kidneys with embryonic kidneys, hoping to identify processes involved in cell differentiation. "The kidney is one of the hardest organs to work on, because it’s so complex, with enormous numbers of tubules," she said.

"We’re using a multi-faceted approach, setting up a lot of different projects and integrating information from all of them."

According to Bertram, a kidney built using the in situ scaffold technique may not end up the same size or shape as a real kidney. "But we believe if we put the right cells in the right environment, they’ll know what to do."

The project is also being funded by a $1 million research grant from Kidney Health Australia. The foundation’s executive officer, Dr Anne Wilson, said some 7200 Australians were currently awaiting kidney transplants.