An engineered triphasic biomaterial scaffold successfully recreated the cranial suture stem cell site lost in craniosynostosis, a condition that causes premature fusion of skull bones. Using a pore-size-guided “bone-suture-bone” design, the scaffold preserved skeletal stem cells while supporting surrounding bone formation. In mouse models, the construct prevented refusion, restored craniofacial growth and improved skull morphology. The findings may advance regenerative therapies that directly address the underlying causes of pediatric craniofacial disorders.
Craniosynostosis is a congenital condition in which one or more of the fibrous joints between the bones of the skull fuse together very early in development. Affecting about one in 2,500 births, the disorder can limit normal brain and skull development, leading to abnormal head shape, increased intracranial pressure, developmental complications and repeated surgeries. Current treatments rely on invasive procedures that reopen or reshape the skull, yet many patients experience re-fusion of the operated sutures, highlighting the need for safer and longer-lasting solutions.
Addressing this challenge, a research team led by Professor Yuji Mishina from the Department of Biological and Materials Science, School of Dentistry at the University of Michigan, USA, together with Dr. W. Benton Swanson from the Department of Oral Medicine, Infection and Immunity at Harvard University School of Dentistry, USA. The team focused on the underlying biological cause of craniosynostosis: the loss of skeletal stem cells that normally reside within the cranial sutures and the immediate growth of the skull. Instead of simply preventing bone formation, they developed a regenerative strategy to rebuild the stem cell site itself. Their findings were published in volume 14 of the journal Bone research on May 28, 2026.
The researchers constructed a biodegradable three-phase scaffold from poly(L-lactic acid), an FDA-approved biomaterial used in multiple medical applications. Inspired by the natural bone-suture-bone structure of the skull, the scaffold contains three interconnected compartments with different pore sizes. A central area of small pores was designed to maintain stem cell properties, while larger pores on either side promote vascularization and bone formation. Together, these compartments created a microenvironment capable of sustaining stem cells while supporting normal skeletal development.
The experiments showed that the scaffold actively guided the behavior of the cells. Skeletal stem cells placed within the central compartment retained their germinal characteristics, while cells that began to differentiate migrated to neighboring areas and contributed to bone formation. The design also created distinct patterns of blood vessel growth and extracellular matrix organization that closely resembled those found in the natural sutures of the skull. Lineage tracing studies further showed that the scaffold maintained a pool of stem cells while allowing their progeny to participate in tissue regeneration.
To determine whether the construct could withstand disease-promoting signals, the team challenged it with excessive activity of bone morphogenetic protein, a pathway associated with abnormal bone formation. Even under these conditions, the central compartment resisted ossification and maintained a niche of non-osseous stem cells. This finding suggested that the altered microenvironment could counteract biological processes that normally trigger premature suture fusion.
The scaffold was then tested in a mouse model of medial craniosynostosis that closely resembles the more common non-syndromic form of the condition in humans. After surgically removing the bonded sutures, the researchers implanted the scaffold into the defect. Animals treated conventionally showed refusion, while those treated with the triphasic scaffold maintained an open suture-like tissue and showed significantly improved craniofacial growth. Earlier intervention produced the strongest benefits, emphasizing the importance of restoring normal growth patterns during critical developmental windows.
“Our goal was not just to reopen a welded suture, but to regenerate the biological niche that allows the skull to grow normally”, said Prof. Mishina. “By recreating the environment that maintains skeletal stem cells, we were able to redirect craniofacial development to a healthier trajectory.”
Dr. Swanson added, “This work demonstrates how rational design of biomaterials can control stem cell fate and tissue organization simultaneously. We believe the principles established here may be broadly applicable to regenerative therapies beyond craniosynostosis.”
Overall, the study demonstrates that rebuilding a stem cell site can be a powerful therapeutic strategy. By combining developmental biology with tissue engineering, the team created a biomaterial scaffold capable of maintaining skeletal stem cells, preventing pathological bone fusion, and restoring more normal skull growth. Beyond craniosynostosis, the findings provide a framework for engineering functional stem cell niches that could ultimately support regenerative therapies for other skeletal disorders and developmental diseases.
