"With his high profile we thought it would be a really good way to be able to spread the word more," Topperwien said.
"It's another big step forward with trying to gain exposure. Taika's got a huge following with Facebook, Twitter and Instagram and he's willing to use those avenues to promote the Foundation and also the need for Maori and Pacific Islanders on the bone marrow registry."
Because of Dream Chaser, a man who signed up to the registry was found to be a bone marrow match for a sick child in French Polynesia recently.
The Topperwiens met Waititi for the first time yesterday and said the star of What We Do in the Shadows was incredibly down to earth.
"He's just a normal guy who is really easy to get along with. He's genuine. Although he is a big superstar he doesn't act like it. It's just like talking to one of the bros really."
Waititi, who heads back to Los Angeles tomorrow, became one of the charity's ambassadors this year along with Sol3 Mio.
He was contacted by Keri who asked him to support the charity and after a phone conference the writer and director agreed.
Waititi, who has two daughters aged 4 and 1, said Chace's story resonated with him.
"It was just like a big emotional bolt that really hit me. Anything that I can do to help kids, any cause that helps kids in need and helps improve their lives is something that I'm always very supportive of."
He was nervous about the needle but said if he could handle getting a tattoo, and compared to the pain sick children endure, joining the bone marrow registry was easy.
Waititi, of Ngati Porou, would only be called up if he was a bone marrow match, and these days a transplant is no longer a painful procedure for the donor, but as simple as donating blood and having it transfused back after the marrow is taken out.
New Zealand Blood Service also pays for travel, accommodation and even lost wages for donors.
Eligible donors should be male, aged between 18 and 40, and of Maori or Pacific Island heritage.
For more information about joining the bone marrow registry visit www.bonemarrow.org.nz