L to R: Dr. Juan Sanchez Ramos, Dr. Ashok Raj and Dr. Chuanhai Cao are part of a multidisciplinary USF health team investigating how GCSF reverses Alzheimer’s pathology.

A recently published study led by University of South Florida neuroscientist Juan Sanchez-Ramos, PhD, MD, is a pivotal example of successful translational research originating at USF Health – starting from a concept and moving to cells, then animals and finally human testing.

Dr. Sanchez-Ramos, with colleagues at USF and James A. Haley VA Hospital, found that a human growth factor known a GCSF, which stimulates stem cells to proliferate in bone marrow, significantly reduces the levels of the brain-clogging protein beta amyloid in mice genetically altered to develop Alzheimer’s disease and reverses the rodents’ memory impairment. The study was reported this summer in Neuroscience, and Dr. Sanchez-Ramos presented the findings at annual meeting of the International Society for Stem Cell Research in Barcelona.

“Our research represents the natural development of a concept – that bone-marrow derived cells might be used to treat neurodegenerative diseases – into a potentially powerful new therapy for Alzheimer’s disease,” said Dr. Sanchez Ramos, who holds the Helen Ellis Chair for Neurology at USF Health. “GCSF may actually reverse disease, not just alleviate symptoms like currently available drugs.”

As a result of the promising findings in mice, the Alzheimer’s Drug Discovery Foundation (ADDF) funded a pilot clinical trial at the USF Health Byrd Alzheimer’s Institute.

The randomized, controlled trial, led by Dr. Sanchez-Ramos and Ashok Raj, MD, is testing the safety and effectiveness of filgrastim (G-CSF) in 12 patients with mild to moderate Alzheimer’s. Cynthia Cimino, PhD, associate professor of psychology, is a co-investigator.

Complementing this new clinical study, Dr. Sanchez-Ramos was recently awarded a highly competitive, five-year, $850,000 VA Merit Grant to further investigate how GCSF works to reverse the pathology of Alzheimer’s disease using the mouse model. His co-investigators are Gary Arendash, PhD; Shijie Song, PhD; Vasyl Sava, PhD; Niketa Patel, PhD; and Chuanhai Cao, PhD.

Like most scientific endeavors, the journey from laboratory to clinic didn’t happen overnight.

A Controversial Idea

More than a decade ago, Dr. Sanchez-Ramos and colleagues published an abstract in the journal Movement Disorders observing that bone marrow contains a certain population of stem cells that could give rise to neuron-like cells. It attracted scant attention.
Then, in 2000, a USF team led by Dr. Sanchez-Ramos and Paul Sanberg, PhD, DSc, announced in Experimental Neurology their success in culling stem cells from both mouse and human bone marrow and reprogramming them in the laboratory to become immature nerve cells.

“The idea that bone marrow might be useful for brain repair was controversial at the time, but since publishing our original paper in Experimental Neurology, hundreds of researchers have been exploring how to harness bone marrow-derived stem cells to treat a wide range of neurodegenerative diseases, trauma and stroke,” Dr. Sanchez-Ramos said.

In 2003, Dr. Sanchez-Ramos and long-time collaborator Shijie Song, an expert in cell culture methods, contributed a review article “Brain as the Sea of Marrow” to Experimental Neurology. The article’s title was derived from the ancient Chinese saying that “brain is a sea of marrow,” indicating that the Chinese believed bone marrow was the source of brain tissue. The piece summarized research at USF and other laboratories showing that bone marrow could give rise to brain cells (although the molecular mechanism for this was not understood) and described how bone marrow-derived cells might be used therapeutically.

When the Alzheimer’s Drug Discovery Foundation took notice and awarded Dr. Sanchez-Ramos an initial grant to test “bone marrow mobilizing agents for Alzheimer’s disease,” the USF researchers had already published several papers describing their findings in cell cultures and mice – including differentiating bone marrow cells into cells that looked and appeared to act like neurons and applying bone marrow-derived cells to treat stroke. They also demonstrated that bone marrow-derived cells pumped out a whole range of growth factors – including GCSF (granulocyte-colony stimulating factor) — that might help protect against or repair assaults on the brain from injury or disease.

A growth factor is like a fertilizer for cells. It increases both the number of cells and their differentiation – that is, it chemically prods cells without well-defined characteristics to become a specific type of cell. So, for instance, bone marrow-derived stem cells exposed in a test tube to various combinations of growth factors may be driven to become microglia, brain cells that act as the nervous system’s main form of immune defense. Some growth factors also help prevent cell death. Dr. Sanchez-Ramos’ team narrowed in on GCSF, a human growth factor possessing both these properties.

A Novel Application

Another big advantage for GCSF was its track record for safety. The growth factor, which prompts bone marrow to produce more blood stem cells and white blood cells, has been routinely administered for years to cancer patients to ward off infection following chemotherapy or radiation. It also helps boost the number of stem cells circulating in the blood of donors before cells are harvested for bone marrow transplants.

“GCSF has been used and studied clinically for a long time, but we were the first group to apply it to Alzheimer’s disease,” Dr. Sanchez-Ramos said.

With the support of a first ADDF grant, Dr. Sanchez-Ramos recruited Gary Arendash of the Florida Alzheimer’s Disease Research Center at the Byrd Institute, to help test GCSF in a mouse model for Alzheimer’s disease. As expected, injections of GCSF mobilized bone marrow-derived cells to migrate from the blood to the brains of the mice. The majority of the bone marrow-derived cells turned into microglia, the brain’s specialized immune cells which infiltrated and reduced the levels of abnormal amyloid protein.

Even more remarkably, GCSF actually reversed memory impairment in mice genetically altered to develop Alzheimer’s disease. Not only did the growth factor significantly reduce levels of the brain-clogging protein beta amyloid overloading the brains of Alzheimer’s mice, it directly stimulated neural stem cells, increased production of new neurons and promoted nerve cell connections. The bottom-line: The memory and thinking abilities of Alzheimer’s mice treated with GCSF improved impressively within a few weeks; in fact, they performed as well as their non-Alzheimer’s counterparts on water maze tests evaluating their learning behavior.

This summer, USF Byrd Alzheimer’s Center began recruiting patients age 55 or older with mild to moderate Alzheimer’s disease to participate in the ADDF-sponsored trial. The 14-week randomized, controlled study is the first to evaluate whether filgrastin (Neupogen) – one of three commercially available GCSF compounds – benefits patients with Alzheimer’s. It is intended to make sure the drug is safe before continuing to larger trials.

As they bridge the gap from mice to humans, the researchers remain cautiously optimistic. “The concept of using GCSF to harness bone-marrow derived cells for Alzheimer’s therapy is exciting, but we still need to prove that this works in humans,” says Dr. Raj, a physician-researcher at the Byrd Alzheimer’s Center.

Challenges of Transformative Research

The Alzheimer’s Drug Discovery Foundation has invested about $300,000 in the USF Health research over the last several years. The New York-based foundation, employing a venture philanthropy model to bridge the funding gap between basic science and later-stage development, works to accelerate the pace of drug discovery for Alzheimer’s disease and related dementias. Impressed by Dr. Sanchez-Ramos pre-clinical work with GCSF, Howard Fillit, MD, the foundation’s executive director, encouraged him to apply for a grant to test the growth factor in humans.

The prospect of stem cell transplantation revolutionizing the treatment of brain diseases has so far fallen short, Dr. Fillit said. Surgically implanting or injecting stem cells into the brain is simply not feasible as a large-scale therapy for a disease like Alzheimer’s that affects more than 5 million Americans, he said. “It will never happen.”

“When Juan initially applied for funds to validate the work he was doing with GCSF in mice, it was somewhat speculative, early-stage research,” Dr. Fillit said. “But, we found his research very attractive because it took a novel approach to neurogenesis that’s practical and, if proven in humans, more immediately applicable to patients”

Dr. Fillit is hoping the trial results in positive results that may open a whole new class of drugs for Alzheimer’s disease.

Cliff Gooch, MD, chair of the Department of Neurology, says foundations like ADDF are essential for physician-scientists like Dr. Sanchez-Ramos who want to explore new compounds that might be transformed into drugs for the prevention and treatment of a variety of diseases, including Alzheimer’s, cancer, diabetes and even less common disorders like ataxias. He points to a recent New York Times article describing how the current federal grant system tends to reward research that makes incremental progress, rather than taking a chance on a higher-risk grant proposal that might make a major difference if it succeeds. NIH reviewers want to see preliminary data showing that an idea is likely to work.

“The number one challenge for this kind of drug discovery work is funding, funding and funding,” Dr. Gooch said. “Often times the start-up dollars for translational research come from a philanthropic organization or foundation willing to invest in an approach that is new and unproven.”

Safety and Commercial Viability

Computerized drug databases make it easier than ever before for translational scientists to search for potential agents with properties that might target specific disease processes inside human cells. But finding a compound with the desired biological mechanism isn’t enough.

“It has to have a tolerable safety profile,” Dr. Gooch said. “Arsenic is very good at killing bacteria, but it has a bad side effect. It can kill you.”

There were several growth factors that Dr. Sanchez-Ramos could have chosen as attractive candidates to test on the Alzheimer’s mice. But GCSF had a big plus, because the compound was already FDA-approved to stimulate bone marrow production and was available commercially.

“That gives you a big leg up because you don’t have to do nearly as much preliminary work establishing safety,” Dr. Gooch said. “But, you still have to prove the compound will be safe and effective in your particular patient population. Just because a drug has been used for years in cancer patients doesn’t mean it will work for people with Alzheimer’s.”

Still, Dr. Gooch is encouraged by Dr. Sanchez-Ramos’ research. The idea of finding injectible agents that could effectively recruit the body’s own stem cells to help directly or indirectly repair the brain is less invasive and technically much simpler than neural transplantation, he said.

“Alzheimer’s is one neurological disease where several potential therapeutic approaches are emerging from the laboratory into human testing, and Juan’s approach is certainly one of the most exciting,” Dr. Gooch said. “As a true physician-scientist he has one foot in the basic science lab and the other in the clinic where he treats patients. That helps him make connections that other researchers without that wider perspective might not see.”

For more information on the GCSF clinical study for Alzheimer’s disease, please contact study coordinator Laura Murray at lmurray1@health.usf.edu or (813) 396-0619. Click here for study brochure.

– Story by Anne DeLotto Baier and photo by Eric Younghans, USF Health Communications