Two decades ago, bone marrow from one little girl saved the life of her sister. And the way it happened still makes news today.

Anissa Ayala’s transplant made national headlines. (Photo by Fred Lee)

On June 4, 1991, Anissa Ayala received bone marrow from her baby sister, Marissa Ayala, who was conceived by a couple desperate to save their ailing daughter’s life. The event was both celebrated and controversial.

Now 39 and 21, the sisters spent the 20th anniversary of the procedure in New York City, where they were invited to NBC’s “Today” show to discuss their story.

It began in 1988, when 16-year-old Anissa Ayala was diagnosed with chronic myelogenous leukemia. A bone marrow transplant was the only option, but no matching donors surfaced.

Inspired by a dream, Anissa Ayala’s parents, Mary and Abe Ayala, believed they could save their daughter by conceiving another child.

The odds were discouraging. Abe Ayala had to have a vasectomy reversed, and even if he and his wife produced another child, there was only a one-in-four chance of a match.

Incredibly, four months later, 42-year-old Mary Ayala became pregnant, and the developing baby would make a compatible donor. Marissa Eve Ayala was born in 1990.

Focused on saving their oldest daughter’s life, the Ayalas soon were astonished to find themselves in the midst of a media firestorm, as medical ethicists and the public weighed in on the case. TIME magazine featured the sisters on its cover and explored the controversy with a story titled “Ethics: Creating a Child to Save Another.”

Anissa Ayala holds her baby sister, Marissa Ayala, while at City of Hope in 1991. (Courtesy of the Ayala family)

Anissa Ayala remains cancer-free two decades later.

Inspired by her parents’ act, Anissa Ayala is creating a foundation to provide financial support for cancer patients’ families, and she is working on a book about her story.

Marissa Ayala, who will be a senior in college next fall, plans to become a speech pathologist.

The Ayalas’ story dramatically underscored the need for bone marrow donors, particularly among minority populations, and helped expand the donor registry.

“That legacy has carried on for 20 years,” said Anissa Ayala’s doctor, Stephen J. Forman, M.D., Francis and Kathleen McNamara Distinguished Chair in Hematology and Hematopoietic Cell Transplantation and chair of the Department of Hematology & Hematopoietic Cell Transplantation. “Many patients since Anissa’s transplant have likely been saved by marrow from donors who were inspired to register by her story.”

On the “Today” show, Marissa Ayala described the deep bond she shares with her sister.

“Without her and her sickness, I would not be here. And without me being a perfect match for my sister, she would not be here, as well,” she said.

To see the Ayala sisters’ interview on the “Today” show, visit www.today.com and enter “Anissa Ayala” in the search box.