Scientists have managed to reproduce the cells that line the human uterus, and it could mean big things for the treatment of endometriosis.

Endometriosis is a common gynecological disorder that occurs when defective cells - similar to those that line the uterus - migrate outside of the womb.

This is every bit as painful as it sounds, but even though endometriosis affects 200 million women worldwide, there is still no long-term treatment.

The new research is a critical step forward. It demonstrates for the first time that human pluripotent stem (iPS) cells can be reprogrammed to become healthy uterine cells.

These are the perfect candidates for transplantation. Not only do they have the potential to fix defects within other cells, they are made from a patient's own skin and blood, meaning they shouldn't be rejected by the immune system.

"This is huge. We've opened the door to treating endometriosis," says lead author Serdar Bulun from Northwestern University, who has been researching treatments for endometriosis for the past 25 years.

Some scientists think endometriosis occurs because cells similar to those that line the uterus are not responding to the hormone progesterone.

This means that instead of staying put, these defective cells might travel through the fallopian tube and into the lower abdomen, where they continue to build up and break down with the menstrual cycle.

These extra-uterine growths can cause severe pelvic pain, inflammation and infertility. They can also increase the risk of developing ovarian cancer.

"These women with endometriosis start suffering from the disease at a very early age, so we end up seeing young high school girls getting addicted to opioids, which totally destroys their academic potential and social lives," says Bulun.

The need for proper, long-term treatment is obvious, and the new research offers some promising results.

iPS cells are sort of like the master key to the human body. They have the potential to make all cells within the body and can perpetually make more copies of themselves.

As a result, an iPS cell has countless different pathways of development. So it's a big deal that scientists have figured out how to manipulate them to create uterine cells in particular.

If these healthy cells, which respond appropriately to progesterone, can be successfully transplanted into the uterus, they could replace the defective cells present.

Not only could this eliminate some of the pain associated with endometriosis, researchers hope it could also be used to treat other disorders of the uterus, like infertility and endometrial cancer.

"One day we hope to make a whole uterus using this cell-based treatment employing the patient's own iPS cells," says Bulun.

That day is still a while off, but the new research offers a glimmer of hope.

Scientists have already tried to transplant a uterus, but because the donated organ is often rejected by the immune system, success has been limited.

Now that scientists know how to produce uterine cells from a person's own skin and blood, the possibilities for future treatments are tremendous.

The study has been published in Stem Cell Reports.