When we say a 3-D printer is being used to help medical professionals, you probably think someone is getting a new arm or leg, but not an ovary.

Researchers with Northwestern University Feinberg School of Medicine in Chicago and Northwestern's McCormick School of Engineering in Evanston, both in Illinois, have used a 3-D bioprinter to create bioprosthetic ovaries to treat infertility in mice.

The bioprinter creates replicas of organs and tissues that cells in the body can attach to, like a scaffold.

"The implant in fact becomes incorporated into the patient's body, and grows, and becomes full of natural hormones, and natural cells," said Benjamin Stewart, an assistant researcher with the University of Denver's Cardiac Biomechanics Laboratory.

Stewart explained how the process works: cells are taken from the patient (in this case mice) and culturedwithout any genetic modification.

The bioprinter then uses cells from the patient, in this case infertile mice, and seeds them into material similar to surgical stitches that dissolve in the body.

"They degrade, and that's why they call it a scaffold, in that it's kind of holding a place directing development in those cells so that the body can break down those polymers," Stewart said.

Researchers created the ovaries from biomaterials to support follicles - the spherical pockets inside ovaries that contain immature egg cells and produce hormones.

They found the ovary scaffold gave the follicles the right support for maturing egg cells and ovulation.

Researchers said it also allowed blood vessel to develop inside the implant so that released hormones could enter the bloodstream and trigger lactation in the mice.

The gelatin they used to create the implants is safe for use in humans and rigid enough for surgery.

Researchers believe this study is bringing us closer to the day when bioengineered implants can be used instead of transplanted donor tissue.

Stewart agrees.

"It's relevant because in many of these cases there's a major deficiency in the donor pool," Stewart said. "Furthermore, those donors are donating an organ that requires immunosuppressant drugs for that recipient. So tissue engineering is going to resolve some of those problems with the number of organs available, and also that it will be patient specific in shape and size, and that it will develop with the recipient. But most importantly, maybe you don't need to take immunosuppressant drugs, you don't need to take anticoagulants like you do in so many of these operations."