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Thursday, May 22, 2025

From "non-essential" to life-saver: the spleen’s hidden role as a built-in bioreactor

Nanjing University School of Life Sciences

image:
Human islets grown in the immune-remodeled spleen of macaques.
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Credit: Credited by Lei Dong/Nanjing University and Jian Xiao/Wenzhou Medical University

Groundbreaking Discovery

What if the human body contained a natural bioreactor capable of regenerating vital organs? A collaborative team from Wenzhou Medical University, Nanjing University, and University of Macau has redefined the spleen’s potential, transforming it into a self-sustaining hub for organ regeneration, as published in Science Translational Medicine (May 21). This breakthrough could revolutionize treatments for type 1 diabetes and beyond.

Redesigning the Spleen: From Filter to "Living Bioreactor"

Confronting the dual challenges of poor islet survival and immune rejection in traditional transplants, researchers posed a bold question: Could we repurpose an underutilized organ to nurture new life?

Led by Prof. Lei Dong and Prof. Jian Xiao, the team engineered smart nanoparticles to reprogram the spleen’s microenvironment. "We’re essentially converting the spleen into a high-performance bioreactor," Dong explains. "By enhancing extracellular matrix support, accelerating blood vessel growth, and suppressing immune attacks, we’ve created an ideal niche for transplanted cells to thrive."

In a landmark achievement, human islet tissues successfully matured within the reprogrammed spleens of cynomolgus macaques, demonstrating compatibility with both human and animal-derived cells. This dual success paves the way for addressing organ shortages through cross-species solutions.

Why the Spleen? Three Biological Superpowers

Ample Space: A porous structure capable of hosting billions of cells

Nutrient-Rich Network: Direct blood supply to the liver’s portal vein mimics natural organ development

Low-Risk Adaptation: Remodeling occurs without disrupting critical bodily functions

Proven Track Record: Regenerating Organs Within the Body

The team’s spleen-based regeneration platform has achieved multiple milestones:

Functional Liver (Science Advances, 2020): Reprogrammed mouse spleens to perform liver functions

In Situ Regeneration (Gut, 2022): Grew liver tissues using gene editing, bypassing cell transplants

Thyroid Restoration (Advanced Science, 2024): Rebuilt hormone-producing tissues in animal models

Future Vision: A Personalized Organ Nursery

Next goal? Growing patient-specific organs from induced pluripotent stem cells (iPSCs). "The spleen acts like a living bioreactor embedded in our bodies," Dong describes. "With minimally invasive B-ultrasound-guided delivery, we could one day cultivate custom-made organs on demand."

While clinical applications require rigorous safety validation, this discovery challenges conventional wisdom. Once deemed "non-essential," the spleen now emerges as nature’s ultimate toolkit for regenerative medicine—proving that life’s most powerful solutions may have been inside us all along.