CHARLOTTE, NC. -- For four years, Luis Pinto has been driving around with a message on the back of his car, "Wife needs a kidney 'O' Blood type."

Pinto's wife, Phyllis, needed a kidney transplant and she needed it soon.

"We tried everything... and I just happened to see somebody else do something on the back of their vehicle and that's where I got the idea," Luis said.

At first, Phyllis was not on board with her husband's seemingly crazy idea.

"I was like you're going to air out my dirty laundry," Phyllis said. But she quickly realized that a sign on the back of her car could be her only chance of reaching a donor.

So Luis began driving up and down I-485 every day in the hopes that someone would call the number on the back of his car.

Eventually, someone snapped a photo and took it to Facebook. It went viral sometime around December.

"We had over a million hits on it," Pinto said. "We've had hundreds of people say they want to donate."

One of those people on Facebook was Heather Johnson. She took a test in January and by April she found out she was a perfect match for Phyllis.

"I didn't feel like I was that special," Heather said. "I just felt like God wanted me to help her. I didn’t think it was that big a deal."

Some might disagree. Heather’s ten-year-old son has kidney issues and could someday need a donor himself. But Heather said she’s convinced she was meant to do this for Phyllis and believes if someday her son needs help, another stranger will be just as generous.

“She’s just a very loving person who wants to give back and help somebody in need," Phyllis said.

“Having a total stranger do something for us; she was sent from heaven," Luis added.

The two women had their surgery at Wake Forest Baptist Hospital early Tuesday morning. Luis told NBC Charlotte that both women are doing well and recovering post-surgery.

Stay with NBC Charlotte as we follow their journey.