Single-Cell Proteomics Reveals Hidden Cardiomyocyte Diversity, Reshaping Precision Medicine and Drug Development

The era of single-cell proteomics is beginning to rewrite fundamental assumptions about cardiac biology, with profound implications for how pharmaceutical companies design and interpret clinical trials. Jennifer Van Eyk, PhD, Director of the Advanced Clinical BioSystems Research Institute and Professor of Cardiology and Pathology at Cedars-Sinai Medical Center查看公司主页, has generated data showing that cardiomyocytes in the human left ventricle are far more heterogeneous than previously recognized—and that this diversity may hold the key to understanding why drugs succeed in some patients and fail in others.

Unmasking Hidden Cellular Diversity

For decades, cardiac researchers operated under the assumption that cardiomyocytes within a given region of the heart were largely uniform. Van Eyk's work, powered by advances in single-cell proteomics that have matured only within the last five years, has upended that view.

"We found at least two distinct cardiomyocyte subpopulations" in the human left ventricle, Van Eyk explained. "The differences are largely driven by sarcomeric proteins and metabolism."

The implications extend well beyond basic biology. When Van Eyk's team treated induced pluripotent stem cell-derived cardiomyocytes with a drug, only one of these subpopulations responded. This finding introduces a paradigm-shifting possibility: when a drug fails in a clinical trial, the conventional assumption is that the compound did not adequately engage its target. Van Eyk's data suggest an alternative explanation—that "the patient's cardiomyocytes were not in a responsive state."

"If that is the case," she noted, "we might need to shift the proteome into a responsive state before administering the drug. That possibility changes how we interpret drug failures and how we design therapies."

A New Lens on Genetic Disease

The power of single-cell resolution becomes even more apparent in the context of genetic cardiomyopathies. Van Eyk's team has been studying a sarcomeric mutation where individuals carrying exactly the same genetic variant can experience dramatically different clinical outcomes—a phenomenon that has long puzzled clinicians.

Using single-cell proteomics, the researchers discovered that mutant and wild-type proteins are not distributed uniformly among cells. "Some cells express mostly wild-type protein, others mostly mutant protein, and many express intermediate ratios," Van Eyk said. "This cellular heterogeneity could explain why patients with the same mutation have very different clinical phenotypes."

She contrasted this with the traditional approach: "People used to just run Western blots to show that the expression of the mutant was at 50%. Now we have the resolution to say, yes, generally, but not every cell is something different."

Implications for Pharmaceutical R&D

Van Eyk is direct about what these findings mean for drug developers. "If I were a pharmaceutical company, I would incorporate single-cell analysis very early in the development process," she said. Currently, such analyses are not standard practice in clinical trial design.

The technology to perform these analyses is no longer a barrier. Mass spectrometers can now generate a complete proteome in approximately 20 minutes, and researchers can track dynamics, study protein localization within cells, analyze entire protein complexes, and perform highly accurate quantification—all at the single-cell level.

"We are now at a mature stage where proteomics can be performed at high throughput, relatively low cost, and with remarkable precision," Van Eyk said. "Many people still think of proteomics as it was 25 years ago, when it was difficult and slow. That is no longer the case."

The Complexity That Explains Biology

At the heart of Van Eyk's scientific philosophy is an embrace of biological complexity rather than an attempt to simplify it. Proteins, she emphasizes, are what make a cell alive—the machinery of life itself. From a limited number of genes, an exponentially larger number of protein forms can be generated through alternative splicing and post-translational modifications.

"Take troponin T (搜索)搜索该靶点, for example. One gene can generate dozens of different protein forms through alternative splicing, and each variant can undergo numerous post-translational modifications," she said.

This complexity is not random. "Protein expression, splicing, modification, and interaction are all highly regulated. There are rules governing these processes." The challenge—and the opportunity—lies in measuring all of it and identifying the key points that can become biomarkers or therapeutic targets.

Toward Personalized Medicine

Van Eyk sees proteomics as already contributing to personalized medicine, particularly in the realm of circulating biomarkers. "For example, in pancreatic cancer (搜索)搜索该疾病, the blood proteome can help predict survival. This allows treatment strategies to be adapted," she noted.

For therapeutics, progress is more measured but advancing. "We are only now realizing that two patients with the same clinical phenotype may have completely different underlying mechanisms. That means they may need different drugs."

The Bottleneck Ahead

Despite the remarkable technological progress, Van Eyk identifies biological interpretation as the field's greatest challenge for the coming decade. "We know the function of only about half of human proteins. Many proteins are still poorly understood and are therefore excluded from our analyses."

She also points to the "dark proteome"—the growing catalog of peptides and proteins whose functions remain entirely unknown. "The bottleneck is no longer measuring proteins. The bottleneck is understanding what the measurements mean."

For Van Eyk, who began her career as a peptide chemist studying how a tiny 12-amino-acid peptide could replace the function of cardiac troponin I (搜索)搜索该靶点, the journey from studying the smallest protein fragments to mapping entire cellular proteomes has been driven by a simple motivation. "I simply loved proteins," she said. "To me, the joy of proteomics is seeing what you did not expect to see or breaking dogma."

As the field moves toward democratization—making methods easier to use while maintaining reliability—Van Eyk emphasizes that harmonizing data obtained around the world "is essential" for proteomics to broadly advance precision medicine. The technology has arrived. The next frontier is making sense of what it reveals.