Researchers were able to grow new pancreas in the bodies of rats using mouse stem cells and then transplanted the organs into diabetic mice.
The findings show that the technique can reverse diabetes at least in laboratory mice that were given drugs to develop diabetes, a life-threatening metabolic disease characterized by the inability to make or appropriately respond to insulin.
Growing Organs Of One Species Inside The Body Of Another Species
The ability to grow organs of a species inside the body of another species may also possibly pave way to producing transplantable human organs grown in large animals such as sheep or pigs.
For the experiment, the researchers implanted mouse pluripotent stem cells into the embryos of rats that were genetically engineered so they would not develop their own pancreas. Pluripotent stem cells have the ability to develop into any cell in the body. The absence of pancreas forced the rats to rely on the mouse cells to develop the organ.
The mouse pancreases were not commonly rejected by the immune system of the rats since mouse cells were injected into the rat embryo before the development of immune tolerance, the period when the immune system is trained to recognize its own tissues.
Once the rats have grown, the insulin-producing mouse cells that cluster together in groups known as islets were transplanted into diabetic mice that were genetically matched to the stem cells that formed the pancreas.
Technique May Reverse Diabetes
The researchers found that the diabetic mice normalized their blood glucose levels for more than a year after the transplant.
The mice also only needed to be treated with immunosuppressive drugs for five days after the transplantation to prevent rejection of the transplanted tissues instead of getting lifelong immunosuppressive treatment needed for unmatched organs. In humans, these drugs are known to have serious side effects.
The transplanted islets contained some contaminating rat cells, which necessitates the use of immunosuppressive drugs, but after a treatment period of five days following the transplant, the immunosuppression was stopped.
"The transplanted islets successfully normalized and maintained host blood glucose levels for over 370 days in the absence of immunosuppression (excluding the first 5 days after transplant)," the researchers wrote in their study, which was published in the journal Nature on Jan 25.
"These data provide proof-of-principle evidence for the therapeutic potential of PSC-derived islets generated by blastocyst complementation in a xenogeneic host."
Possible Solution To Shortage Of Organs For Transplant Patients
When the researchers removed islets from some of the mice after 10 months for inspection, they found that the immune system of the mice has eliminated the rat cells
"This is very promising for our hope to transplant human organs grown in animals because it suggests that any contaminating animal cells could be eliminated by the patient's immune system after transplant," said study researcher Hiromitsu Nakauchi, from Stanford.
The findings of the study offer hope for a means to alleviate the shortage of life-saving human organs for transplant patients.