Unknown Organelle Discovered Inside Our Cells

The discovery of an unknown organelle inside our cells could open the door to new treatments for devastating inherited diseases. 

The organelle, a type of specialized structure, has been dubbed a “hemifusome” by its discoverers at the University of Virginia School of Medicine and the National Institutes of Health. This little organelle has a big job helping our cells sort, recycle and discard important cargo within themselves, the scientists say. The new discovery could help scientists better understand what goes wrong in genetic conditions that disrupt these essential housekeeping functions.

“This is like discovering a new recycling center inside the cell,” said researcher Seham Ebrahim, PhD, of UVA’s Department of Molecular Physiology and Biological Physics. “We think the hemifusome helps manage how cells package and process material, and when this goes wrong, it may contribute to diseases that affect many systems in the body.”

One such condition is Hermansky-Pudlak syndrome, a rare genetic disorder that can cause albinism, vision problems, lung disease and issues with blood clotting. Problems with how cells handle cargo are at the root of many such disorders.

“We’re just beginning to understand how this new organelle fits into the bigger picture of cell health and disease,” Ebrahim said. “It’s exciting because finding something truly new inside cells is rare – and it gives us a whole new path to explore.”

Hello to the hemifusome

Ebrahim and her team at UVA Health worked with Bechara Kachar, MD, and colleagues Amirrasoul Tavakoli, PhD, and Shiqiong Hu, PhD, at the National Institutes of Health to identify the organelle, which comes and goes as needed by the cell. They took advantage of UVA’s expertise in cryo-electron tomography (cryo-ET) – a powerful imaging method that “freezes” cells in time – to create striking images of the organelle.

The scientists believe hemifusomes facilitate the formation of vesicles, tiny blister-like sacs that act as mixing bowls, and of organelles made up of multiple vesicles. This process is critical to cellular sorting, recycling and debris disposal, the researchers report. 

“You can think of vesicles like little delivery trucks inside the cell,” said Ebrahim, of UVA’s Center for Membrane and Cell Physiology. “The hemifusome is like a loading dock where they connect and transfer cargo. It’s a step in the process we didn’t know existed.”

While the hemifusomes have escaped detection until now, the scientists say they are surprisingly common in certain parts of our cells. The researchers are eager to better understand their importance to proper cellular function and learn how problems with them could be contributing to disease. Such insights, they say, could lead to targeted treatments for a range of serious genetic disorders.

“This is just the beginning,” Ebrahim said. “Now that we know hemifusomes exist, we can start asking how they behave in healthy cells and what happens when things go wrong. That could lead us to new strategies for treating complex genetic diseases.”

Reference: Tavakoli A, Hu S, Ebrahim S, Kachar B. Hemifusomes and interacting proteolipid nanodroplets mediate multi-vesicular body formation. Nat Commun. 2025;16(1):4609. doi: 10.1038/s41467-025-59887-9

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