Imagine recovering from a severe injury, only to find your body betraying you by growing bone where it shouldn’t. This is the harsh reality for many patients who develop heterotopic ossification (HO), a condition where abnormal bone forms in soft tissues like muscles and tendons, leading to chronic pain and disability. But here’s where it gets controversial: could the key to preventing this devastating complication lie in two proteins that were once thought to simply aid healing? A groundbreaking study suggests just that, and it’s sparking a debate in the medical community.
In a recent investigation, researchers led by Dr. Benjamin Levi from the University of Texas Southwestern uncovered the surprising role of thrombospondin 1 (TSP1) and thrombospondin 2 (TSP2) in driving HO. These proteins, traditionally recognized for their part in tissue repair, appear to orchestrate a harmful transformation in injured tissues, turning them into fertile ground for unwanted bone growth. Published in Bone Research, the study not only sheds light on the molecular mechanisms behind HO but also proposes a novel strategy to prevent it—by targeting these very proteins.
But here’s the part most people miss: While the body’s natural healing process is designed to restore function after injuries like burns, fractures, or surgeries, it sometimes goes awry. Instead of rebuilding healthy tissue, it starts producing bone in places it shouldn’t, causing stiffness, pain, and long-term disability. This condition, often seen after trauma or joint replacement surgeries, has puzzled scientists for years. Despite its significant impact, the biological processes driving HO have remained largely mysterious—until now.
Using advanced techniques like single-cell RNA sequencing and high-resolution imaging, the research team discovered that TSP1 and TSP2 play distinct roles in reshaping the injured tissue environment. TSP1, primarily produced by immune cells called macrophages, works alongside TSP2, which is generated by mesenchymal progenitor cells (MPCs)—cells capable of developing into bone-forming cells. Together, these proteins alter the arrangement of collagen fibers, creating a rigid structure that supports bone growth. When the researchers genetically removed both proteins in mice, the collagen fibers remained disorganized, and abnormal bone growth was significantly reduced.
And this is where it gets even more intriguing: The study also identified a regulatory protein called FUBP1, which controls TSP2 production. By reducing FUBP1 levels in lab-grown cells, the researchers were able to lower TSP2 production, effectively weakening the signals that promote harmful tissue remodeling. However, the findings are primarily based on animal models, leaving a critical question: Will these mechanisms translate to humans? And if so, how can we safely target these proteins without disrupting normal healing processes?
Dr. Levi emphasizes the potential of this discovery: ‘HO can be life-altering for many patients. By understanding the roles of TSP1 and TSP2 in HO formation, we hope to develop therapies that target these proteins and prevent HO before it causes permanent damage.’ But this raises a thought-provoking question for the audience: If we can block these proteins to prevent HO, should we? And what are the potential risks of interfering with proteins that also play a role in normal healing?
This study not only opens new avenues for treating HO but also invites a broader discussion about the delicate balance between healing and harm in the body’s repair mechanisms. What do you think? Is targeting TSP1 and TSP2 a promising approach, or are we risking unintended consequences? Share your thoughts in the comments below.
Reference
Title: Thrombospondin 1 and 2 regulate mesenchymal progenitor cell fate and matrix organization
Journal: Bone Research
DOI: 10.1038/s41413-025-00493-2
About University of Texas Southwestern
The University of Texas Southwestern is a leading academic medical center, renowned for integrating cutting-edge biomedical research with exceptional clinical care and education. Its faculty includes six Nobel laureates and numerous members of prestigious scientific academies, driving groundbreaking medical advances and translating research into innovative treatments.
About Dr. Benjamin Levi
Dr. Benjamin Levi is a Professor at the Center for Organogenesis and holds the Dr. Lee Hudson–Robert R. Penn Chair in Surgery at the University of Texas Southwestern. With over 15 years of research experience and more than 100 publications, his work focuses on heterotopic ossification, tissue regeneration, stem cell biology, and wound healing.
Funding Information
This research was supported by the Department of Defense (grant HT9425-23-1-0327) and the National Institutes of Health (R01AR078324).
Contact
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Bone Research Editorial Office
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