Faculty Profile: Dr. Gay M. Crooks

Dr. Gay Crooks

From a very early age, Gay Crooks, MBBS, was interested in medicine and medical science. “I didn’t come from a medical or scientific family, but they were also fascinated with the field,” Dr. Crooks says, “and strongly encouraged me to pursue medicine.” Dr. Crooks cannot remember ever wanting to be anything other than a physician and was motivated by the noble mission and profound impact she saw in clinicians using knowledge and science to help people.

As a pediatric oncologist, Dr. Crooks is very experienced in stem cell science, which has been the basis of bone marrow transplantation for treatment of leukemias for decades. As a leader in the field, she has driven the concepts and created some of the tools used in more recent stem cell science, which has evolved and expanded enormously in the last ten years. “When I was working in the bone marrow transplant division at Children’s Hospital Los Angeles, no one was studying stem cells, which I found fascinating. I’ve found my niche studying them in the human system, as they have been studied quite extensively in the mouse system.”

Dr. Crooks focuses her research at the UCLA Stem Cell Center on hematopoietic or blood stem cells, which develop into the different types of blood cells. Over the past ten years she has concentrated on understanding how stem cells become the cells of the immune system.

The Thymus and Immune System Cells
In studying the processes of the immune system, Dr. Crooks and her colleagues also became interested in a gland called the thymus that sits just behind the breast bone in front of the heart, and produces blood cells called T cells, that serve as the soldiers of the immune system. The Crooks lab studies the thymus and how it instructs the stem cells to become T cells. That research has led her team to create a “thymus in a dish” model.

“This is a very exciting regenerative tissue project,” Dr. Crooks says, “because the thymus works very well during childhood, but by the time of middle age it is mostly replaced by fat and the tissue that remains to program the T cells is very limited. When chemotherapy is given to an older person, it knocks out what little thymic function they have left and they become more susceptible to infections. Thus, the older you get the harder it is for the body to restore the immune system after such insults as chemotherapy, radiation treatment, or bad infections.”

Dr. Crooks ultimate research goal is to learn how to return function of the thymus to make and control T cells that will help bolster the immune system. Simultaneously, she and her lab must avoid causing autoimmune diseases such as inflammatory bowel disease, multiple sclerosis, diabetes, or rheumatoid arthritis.

As Co-Director of the Stem Cell Center, Dr. Crooks helps guide the Center’s large and diverse membership to achieving its mission: bringing about the scientific revolution of regenerative medicine. A professor of pathology and laboratory medicine, pediatrics and orthopedic surgery, Dr. Crooks also shares her vast experience through lectures to UCLA undergraduates, medical students and doctoral science students.

A View into the Future
As her research progresses, Dr. Crooks hopes that she and her team can tissue-engineer a thymus using the patient’s own cells that can be expanded outside the body and transplanted into the patients, allowing them to have healthy immune systems. A prime candidate group for this treatment would be children with DiGeorge syndrome, a congenital anomaly in which children are born without thymuses and cannot make T cells. This syndrome is often fatal because the lack of T cells leaves patients susceptible to myriad diseases usually kept at bay by a healthy immune system.

“Currently we are making thymuses from existing tissue removed during cardiac surgery,” Dr. Crooks says, “we would like to move to thymuses grown from pluripotent stem cells derived from a patient’s own skin cells. A thymus made this way would match perfectly and eliminate the risk of rejection.”

Dr. Crooks was recruited to UCLA in 2009 to join the Stem Cell Center, the Jonsson Comprehensive Cancer Center and the David Geffen School of Medicine departments of pathology and pediatrics. Her world-class experience as a physician-scientist is leading UCLA to great scientific discoveries, as well as training and mentoring the scientists who will take stem cell science further into its bright future.