By Stacy Jacobsonsjacobson@abcnews4.com
CHARLESTON, S.C. (WCIV) -- Mack Schieder has been fighting most of his six years. He's spent them in and out of the hospital.
"It changes who you are, who your children are. My children have grown up in a hospital environment," his mother Laura Schieder said.
Mack was diagnosed at 19 months with acute mixed lineage leukemia. He underwent chemotherapy for three and a half years. They thought he was clear, but months later, just after he started kindergarten, it came back.
As Scout Schieder ran around outside MUSC Thursday, she looked like any other three-year-old kid enjoying the sunny day.
No one would know behind her sweet face, that she endured pain to help save her brother's life. She gave him her bone marrow.
"She had a very large needle put in her lower back on each side and they aspirated about 200 millimeters of bone marrow from Scout," Laura Schieder said. "It was a 25-percent chance she'd be a match and she was 100 percent match. So we're thankful. I think God put her here for a reason."
Now, the siblings are bound by more than love.
"They infused it in to Mack about three hours after they retrieved it from Scout," she said.
During all this, Mack's schoolmates and teachers wanted to help.
"Everyone wants to do something because they love him so much," Mack's kindergarten teacher Kerry Sturm said.
So, they played in Mack's honor. Pivotal Fitness raised about $700 to help pay for Mack's medical bills.
And back at the hospital, as mother and daughter walk back in to the place they've grown to call home, all the support helps them see a different future walking to their real home, instead.
For more information on becoming a bone marrow donor, click here. Potential donors need to do a mouth swab to become part of the donor list. Doing the swab does not entail making any commitment to donating.
Mack's doctors said he was responding as well as could be expected. They hoped to have him better in time for the first day of school 2014.