This revolutionary field still faces many challenges, including the nontrivial task of convincing stem cells to differentiate into desired cell types for treatment. And even if the correct cells or tissues are created and can function successfully in the body, immune rejection presents a formidable barrier to their use. To overcome this obstacle, regenerative medicine treatments in use today require systemic immunosuppression, leaving patients vulnerable to environmental hazards like viruses, bacteria and cancer cells.

In a novel approach to tackle these obstacles, researchers at the Medical University of South Carolina and the University of Florida recently collaborated on a novel, highly specific strategy to treat type 1 diabetes (T1D) using a tagged beta cell transplant in tandem with localized immune protection provided by specialized immune cells also tagged with a complementary but inert targeting molecule.

According to Leonardo Ferreira, Ph.D., a researcher at MUSC Hollings Cancer Center and one of the principal investigators on the study, marrying stem cell engineering and regulatory T cell (Treg) engineering allowed the first step toward a readily available, off-the-shelf solution to treating T1D.

In their recent study published in the journal Cell Reports, the researchers described a unique collaboration that leveraged the beta cell engineering expertise of the lab of Holger Russ, an associate professor of pharmacology and therapeutics at the University of Florida, combined with the delicate surgical expertise and chimeric antigen receptor (CAR) T cell expertise available at Hollings.

For T1D patients, the trouble begins with an immune system self-attack on pancreatic beta cells, the cells that produce the hormone insulin to regulate blood sugar levels. Without a reliable way to self-regulate blood glucose levels, patients are forced to live with a high-maintenance regimen of glucose monitoring and insulin management to maintain health and avoid dangerous complications like neuropathy, amputation and blindness.

For now, some patients with poorly controlled T1D may consider islet cell transplantation using beta cells from a donor. Beta cells are isolated from a donor pancreas, purified and delivered to the patient’s liver, where they can take up residence and begin secreting insulin. However, this option requires patients to undergo immunosuppression for the rest of their lives to keep the body from rejecting the foreign beta cells. It also requires the availability of donor cells, which might require long waits or may not happen at all.

To focus on an alternative solution, the researchers used an engineering strategy with tagged beta cells generated from stem cells. And to induce localized immune protection, the researchers chose to use Tregs, a type of immune cell that monitors and controls the immune response.

“Most of the cells of the immune system are focused on killing invasive elements,” Ferreira said. “But Tregs are the generals of the immune system. They make sure that nothing goes overboard, and they train the immune system on how to respond in the future.”

The researchers used a mouse model to test their strategy. By transplanting beta cells that were engineered from stem cells and included a nonreactive tag — an inactivated version of epidermal growth factor receptor — into the kidney capsules of immunodeficient mice, they showed that the cells were incorporated and began to manufacture functional insulin. In the next phase of testing, the mice were exposed to an aggressive type of immune cell to check on the viability of the transplanted beta cells in the face of a simulated immune response. As expected, all of the beta cells were killed by the immune response, the same thing that happens in people with T1D.

To avoid the killing response in the next phase, the researchers added specialized Tregs along with the immune challenge. These cells were tagged with CAR technology using a receptor that specifically recognized the inert EGFR tag present on the transplanted beta cells. With this added step, the researchers observed the immune protection they hoped for, as they observed the transplanted beta cells remaining safe, sound and functional in their new home.

Ferreira was delighted with the results and energized to take the next steps. “With this approach,” he said, “we made both the lock and the key for creating immune tolerance.”

Now that Ferreira and colleagues have shown the feasibility of their approach to T1D treatment, they plan to continue their research efforts, including building a whole library of locks and keys — differentiated stem cells and tagged protective Tregs — for multiple purposes, such as targeting certain cancers, lupus and other autoimmune diseases.

A few questions remain, such as the specific ligand that should be used for human transplantation and the longevity of Treg-mediated immune protection. The ligand or tag must be inert and have no negative impact on the function of the cells or create any reaction that could cause side effects. And it is still unknown if one Treg treatment will be effective or might need to be repeated at intervals that have yet to be established. Because Tregs can educate immune cells to maintain immune tolerance, it is possible that one treatment will be adequate, but further research is needed to understand the long-term effects.

Answering these questions and confirming the validity of the approach in humans may soon transform T1D from a chronic, high-maintenance disease with many complications to one that can be managed much more easily.

“Establishing such biomarkers could provide a key step in changing how we care for, treat, and offer interventions to people with psychosis,” said Brian Keane, PhD, assistant professor of Psychiatry, Center for Visual Science, and Neuroscience at the University of Rochester Medical Center. Keane recently co-authored an article in Molecular Psychiatry that identifies how MRI scans could reveal brain differences in people with psychosis. “Aside from potentially predicting future psychosis onset, biomarkers could also help stratify patients into clinically meaningful subgroups and suggest new options for treatment or intervention.”

Using data collected by the Human Connectome Early Psychosis Project, researchers looked at MRI scans from 159 participants. These included 105 who developed a psychotic disorder up to five years prior to testing. In the brains of participants with psychosis, researchers found that sensory regions in the cortex were more weakly connected to each other and more strongly connected to the thalamus, the brain’s information relay station. These differences were confined to the somatomotor network, which processes bodily movement and sensations, and a visual network, which generates representations of objects, faces, and complex features. Combining the dysconnectivity patterns across these two networks allowed the researchers to create a “somato-visual” biomarker.

Previous research has suggested that abnormal brain connectivity exists prominently in the sensory networks of people with schizophrenia, but it remained unclear which networks were most responsible or whether dysconnectivity could be explained by other illness factors, such as antipsychotic use, anxiety, or stress.

“What makes this biomarker unique is its large effect size, its robustness to over a dozen common confounds, and its high reliability across multiple scans. A single five-minute scan could potentially improve our ability to predict which at-risk individuals will transition to a psychotic disorder, which in turn could allow for more timely treatments or interventions,” Keane said. “It also gives us a place to keep looking. An important next step will be to determine if the somato-visual biomarker emerges before or as psychosis begins.”

Additional authors include Yonatan Abrham, Boyang Hu, and Brent Johnson of the University of Rochester, Carrisa Cocuzza of Yale University, and Michael Cole of Rutgers University. This work was supported by a K01 grant and a Psychiatry Department pilot grant at the University of Rochester.

The study, published Nov. 25 in Nature Aging, may lead to new longevity treatments that could extend human lifespan. It also establishes a mortality timer that reveals how long a cell has left before it dies.

As people get older, they are more likely to develop health conditions, such as cancer, cardiovascular disease and neurodegenerative diseases.

“Aging is the highest risk factor for these diseases,” said Dr. Jessica Tyler, professor of pathology and laboratory medicine at Weill Cornell Medicine. “Rather than treating each disease separately, a better approach would be to develop a therapeutic or supplement that will delay the onset of diseases by preventing the underlying molecular defects that cause them.” The nucleolus may hold the key.

Small Packages

The nucleus holds the cell’s chromosomes and the nucleolus where the ribosomal DNA (rDNA) is housed. The nucleolus isolates the rDNA which encodes the RNA portions of the ribosomes, the protein-building machinery. The rDNA is one of the most fragile parts of the genome, due to its repetitive nature making it more difficult to maintain and fix if damaged. If damage in the rDNA is not accurately repaired, it can lead to chromosomal rearrangements and cell death.

In organisms from yeast to worms to humans, nucleoli expand during aging. On the flip side, anti-aging strategies like calorie restriction, or eating less, result in smaller nucleoli. “Calorie restriction does so many different things, and no one knows the precise way that it is extending lifespan,” Dr. Tyler said.

Dr. Tyler and postdoctoral fellow Dr. J. Ignacio Gutierrez, the first author of the paper, suspected that keeping nucleoli small could delay aging. To test this idea, they engineered an artificial way to secure rDNA to the membrane surrounding the nucleus of yeast cells so they could control when it was anchored and when it was not. “The advantage of our system is that we could isolate the nucleolus size from all of the other effects of anti-aging strategies,” Dr. Gutierrez said.

The researchers discovered that tethering the nucleolus was enough to keep it compact, and small nucleoli delayed aging to about the same extent as calorie restriction.

Final Moments

Interestingly, nucleoli did not expand at the same rate during the entire lifespan as cells aged. They remained small for most of the yeast’s life, but at a nucleolar size threshold, the nucleoli suddenly began to grow quickly and expand to a much larger size. Cells only survived for an average of about five more cell divisions after hitting this threshold.

“When we saw it wasn’t a linear size increase, we knew something really important was happening,” said Dr. Gutierrez. Passing the threshold appears to serve as a mortality timer, ticking down the final moments of a cell’s life.

During aging, DNA accumulates damage, some of which can be devastating to the cell. In tests, the team found that large nucleoli had less stable rDNA than smaller ones. Also, when the structure is large, proteins and other factors that are usually excluded from the nucleolus are no longer kept out. It’s as if the nucleolus becomes leaky, letting in molecules that can wreak havoc on the fragile rDNA.

“The whole point of condensates is to separate biological reactions to help them work efficiently, but now when you have other proteins coming into the nucleolus, it leads to genome instability, which triggers the end of the lifespan,” Dr. Tyler said. These proteins can cause catastrophic problems, such as chromosomal rearrangements, to build up.

Next, the researchers plan to study nucleolar effects on aging in human stem cells. Stem cells are special because they have the potential to replace other cell types as they die. But eventually, the stem cells stop dividing, so the researchers hope to use the knowledge gained from this project to make them last longer.

“I was excited that we could connect the structure of the nucleolus with the repair process in a way that could be conserved from yeast to humans,” said Dr. Gutierrez.