Researchers at the Hebrew University of Hadassah have demonstrated a remarkable breakthrough: they produced male and female stem cells that share the same genetic code from a single individual. The work appears in Stem Cell Reports and highlights how sex chromosomes drive key biological differences.
Sex chromosomes play a central role in how traits develop in the human body. In humans, males carry an XY pair and females carry XX. Because of this chromosomal difference, treatments for diseases often yield different outcomes for men and women, a factor that scientists must consider when designing therapies and evaluating drug responses.
In this study, the team created two sets of stem cells that are genetically identical in every respect except for the sex chromosomes. The donor was a person who has the genetic condition known as Klinefelter syndrome, a situation where individuals have two X chromosomes and one Y chromosome in their cells. This condition occurs in a small fraction of men, and the unique donor provided a rare opportunity to observe how cells with XX and XY compositions can originate from the same genetic background.
According to the researchers, the blood cells from this donor were transformed into induced pluripotent stem cells, which are capable of evolving into any cell type. From these cells, they isolated populations that differ only in their sex chromosomes. The scientists explain that these transformed stem cells offer a powerful model for studying how sex differences manifest across a wide range of tissues and cell types in the human body, all while keeping genetic background constant. This consistency helps isolate the effects of the sex chromosomes on cellular behavior and drug response.
The implications are significant for the future of personalized medicine. With pluripotent stem cell models that reflect both XX and XY states from the same individual, researchers can compare how male and female cells react to drugs, toxins, and environmental factors without interference from other genetic variations or differing environmental histories. This approach could accelerate the discovery of sex-specific disease mechanisms and lead to more tailored therapies for conditions such as metabolic disorders, cardiovascular diseases, and neurodegenerative illnesses.
Beyond therapeutic testing, the ability to generate paired XX and XY cell lines from a single donor provides a new framework for studying how sex chromosomes influence development, metabolism, and cellular aging. By controlling for the genetic background, scientists can more accurately identify which cellular pathways are driven by the presence of one or two X chromosomes, or by the Y chromosome itself. This knowledge may shed light on why men and women experience certain diseases differently and how sex-related factors modulate the effectiveness of potential treatments across diverse populations in North America. This type of research supports the broader goal of precision medicine, where biological sex is treated as a fundamental variable in medical study design and drug evaluation.
The work underscores a growing recognition that sex-specific biology should be integrated into research planning, therapeutic development, and clinical trials. As scientists continue to map how sex chromosomes shape cellular behavior, the medical community can move toward more nuanced, inclusive strategies that address the needs of all patients. In this context, studies like this one offer a compelling path forward for understanding sex differences at the cellular level and translating that understanding into grounded, real-world health benefits.
Reference context: findings contribute to ongoing efforts to model sex differences in human biology using stem cell technology and genomic insights. While excited researchers note the potential, they also emphasize careful consideration of how such models translate to living organisms and clinical practice. The study represents a meaningful step in a longer journey toward fully understanding how sex chromosomes influence health and disease.