Meet the 9- and 11-Year-Old Sisters Whose Lives Christina Applegate Is Trying to Help Save

Courtesy The Van Sciver Family; Inset: Jeff Kravitz/FilmMagic

This Christmas, two adorable sisters from Inglewood, California are asking for a bone marrow donor to save their lives — and Christina Applegate is using her voice to help find a match.

Kimora, 11, and Kylie Van Sciver, 9, are often with their "second family" at Children's Hospital Los Angeles, where they get treatment for the complications caused by sickle cell anemia, their mom Destiny tells PEOPLE.

"I feel like nothing compares to the suffering that Kimora and Kylie have endured through my life, and seeing it as a mother firsthand," says Destiny, 33. "Having a front seat to it is the worst thing you can imagine."

According to DKMS, the largest blood marrow donor center in the world, about one in every 365 Black children is born with sickle cell disease, and approximately 100,000 Americans have it. Those who suffer from sickle cell anemia don't have enough healthy red blood cells moving oxygen throughout their bodies. That can result in organ damage, pain episodes, blindness, delayed growth and early death.

But the heartbreaking impact can be stopped with a successful bone marrow transplant. Because the girls are sisters, the same donor would work for both of them. (To see if you're a match, register with DKMS and get a free at-home swab kit here.)

Courtesy The Van Sciver Family The Van Sciver family (l-r): Destiny, Kylie, Kimora, Dennis

Christina Applegate is familiar with the easy process. About 10 years ago, the actress was swabbed after learning about brothers Keane and Ethan, who both suffered from a genetic blood disorder. Applegate wasn't a match, but she encouraged others to get swabbed, and eventually a 34-year-old woman in Germany became Keane and Ethan's life-saving hero.

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This year, when a friend from Applegate's daughter's school told Applegate about "the most amazing kids," Kimora and Kylie, she knew she could raise awareness about the impact that joining DKMS' bone marrow registry could have.

"I really want to not only bring awareness to DKMS, but also, we want to save these girls' lives," the breast cancer survivor, 49, tells PEOPLE. "I can't imagine as a mother, having both your daughters with this disorder, and they can't find a match. The more we can get people to do this, then the bigger chance that they have of surviving."

Applegate says she's speaking out in the hopes of another happy ending, this time for Kylie and Kimora.

"I just feel like that everybody deserves a chance, and these girls deserve a chance," the actress says. "All you have to do is swab your mouth... and send it back. You may be the person that could save these girls' lives, or someone's life."

Courtesy The Van Sciver Family Kimora Van Sciver

For Kimora, a successful transplant would put an end to the joint pain and bone necrosis she's been experiencing. Though she went home from the hospital last weekend, she's scheduled to return for a hip replacement surgery on Dec. 30.

"Sometimes it can feel like someone's just stabbing you over and over in your leg," says the aspiring swimmer. "It's not so fun. It really hurts a lot. Words can't really express how much pain it is."

"Even right now, I can't walk downstairs, down my house," says the child, who has been using a wheelchair. "I can't get in my bed by my own. In the summer, I would love to be on a swim team, but I can only swim in the summer when it's over 90 degrees. It prevents so much."

"Right now we have to do this interview in the bed," adds her mom, "because this is the most comfortable position for her."

Courtesy The Van Sciver Family The Van Sciver family (l-r): Destiny, Kylie, Dennis, Kimora

Destiny says the situation for her family — including husband Dennis, 33 — is made worse by the safety precautions hospitals must take due to the pandemic.

"This separation for siblings has been very difficult," Destiny says of her daughters, who find inspiration from their favorite performers, Beyoncé and Zendaya, to keep up the fight. "We have been in the hospital over 11 times in this one year. That's a lot of separation as a family unit."

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Kylie — who suffers from spinal issues but hopes to someday pursue her passion for track — is already thinking about what she wants to tell the person who could change everything for the duo.

"I want to say thank you," says Kylie, "because we could all be together after this, and Kimora and I could feel better."

Courtesy The Van Sciver Family Kylie Van Sciver

Their mom, meanwhile, has a personal message for Applegate, who is advocating for Kimora and Kylie while preparing for season 3 of her hit Netflix show, Dead to Me.

"You didn't have to do what you're doing, and I know everyone is going through something right now," says Destiny, who has been a fan since Applegate's breakout role on Married with Children. "You took out time out of your day, away from your family to help my family. Thank you."

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When the mom learned of Applegate's efforts, "I thought, 'Wow, look at God,'" says Destiny. "People are always thinking, 'What can I do during 2020 to give back and to make a difference?' Having her involved is going to highlight those thoughts in people's minds to do something, to make a difference."

The team at DKMS hopes that someday "every patient will be saved from blood cancer and other blood disorders."

"When they get sick, we have a solution for them; whether it’s a donor, improving therapies through research, or simply helping to provide access to transplantation," says Katharina Harf, vice chairman of the DKMS global board. "In this approach, we see no borders, believing that everyone, everywhere, deserves a second chance at life. We will keep fighting for them and keep spreading the word, recruiting donors, raising money. Whatever it takes to make this dream a reality.”