temporary rooms inside the cell furnished with selected molecular tools
Within the intricate architecture of living cells, UCLA researchers have found a way to build new rooms — artificial compartments assembled from RNA that follow programmable instructions rather than biological chance. Published in Nature Nanotechnology in late April 2026, the work transforms RNA from a passive messenger into an architect, allowing scientists to specify where cellular structures form, what they contain, and what work they perform. It is a quiet but consequential step in the long human effort to understand and reshape life from the inside out.
- Existing methods for engineering cellular compartments rely on proteins that clump unpredictably, leaving researchers with limited control over where and how synthetic structures form.
- UCLA scientists designed RNA 'nanostars' — branched molecular shapes that lock together through precise base-pairing rules, self-assembling into droplet-like compartments inside living cells.
- The team demonstrated they could tune the location, size, and molecular contents of these artificial organelles simply by adjusting the RNA sequence — shifting structures between the cytoplasm and nucleus at will.
- Because RNA demands fewer cellular resources than protein-based approaches, the method is less disruptive to the cells it inhabits, lowering a key barrier to practical use.
- A patent application is already filed, and the technology is being aimed at nanomedicine, gene regulation, and cell engineering — fields where the ability to place a functional compartment exactly where it is needed could prove transformative.
Inside living cells, certain structures form not through rigid membranes but through spontaneous clustering — droplet-like compartments where molecules gather to perform tasks, then dissolve when the work is done. These biomolecular condensates are among the cell's most elegant solutions to the problem of organization. Now, UCLA researchers have learned to build artificial versions of them, using RNA as both the raw material and the blueprint.
The central invention is what the team calls a nanostar: a short RNA strand folded into a shape with three or more outward-reaching arms, each tipped with a sequence that binds predictably to matching sequences on neighboring nanostars. Because RNA obeys consistent base-pairing rules, these structures link into orderly networks that grow into droplet-like compartments. By adjusting arm number, length, and binding strength, researchers can program precisely how the assembly unfolds.
Lead researcher Elisa Franco, a professor of mechanical and aerospace engineering and bioengineering at UCLA, framed the approach as architectural engineering at the molecular scale. Doctoral candidate Shiyi Li, who led the experimental work, demonstrated that the team could control not just whether condensates formed, but where — cytoplasm or nucleus — and which molecules they recruited, effectively furnishing each temporary cellular room with chosen tools.
The research, published in Nature Nanotechnology on April 29, 2026, was supported by the National Science Foundation, the Alfred P. Sloan Foundation, and the National Institutes of Health. With a patent already filed, what began as a fundamental question about programming matter is now pointing toward applications in drug delivery, gene regulation, and synthetic cell engineering — a frontier where biology and engineering grow harder to tell apart.
Inside every living cell, there are smaller structures doing the work that keeps the cell alive. Some are wrapped in membranes—the nucleus, the mitochondria—but others are more like temporary rooms, droplet-shaped clusters of proteins and RNA that form when needed and dissolve when the job is done. These membrane-less structures, called biomolecular condensates, act as workspaces where molecules gather to perform specific tasks more efficiently than they could scattered throughout the cell.
Researchers at UCLA have now figured out how to build artificial versions of these condensates from scratch, using RNA itself as both the building material and the instruction set. The work, published in Nature Nanotechnology on April 29, represents a shift in how scientists think about engineering the cell's interior. Rather than relying on proteins that naturally clump together in unpredictable ways, the team encoded assembly instructions directly into RNA sequences, giving them precise control over how, where, and when these artificial compartments form.
The key innovation is a structure the researchers call a nanostar—a short strand of RNA folded into a shape with three or more arms extending outward. At the tip of each arm sits a sequence called a kissing loop, a region that binds to matching sequences on other nanostars. Because RNA follows predictable rules about which bases pair with which, these nanostars link together in orderly networks, building up into larger droplet-like structures. The researchers can program exactly how these networks assemble by adjusting the number of arms, their length, and the strength of the interactions between them.
Elisa Franco, the study's lead researcher and a professor of mechanical and aerospace engineering and bioengineering at UCLA, described the approach as a form of architectural engineering applied to the cell's interior. Using RNA as a building material, she noted, allows researchers to create customizable compartments while consuming fewer of the cell's resources than protein-based methods would require. Shiyi Li, the doctoral candidate who led the experimental work, emphasized the practical control this offers: the team can determine not just whether condensates form, but where they appear—in the cytoplasm or the nucleus—and what molecules they attract, essentially furnishing these temporary cellular rooms with selected molecular tools.
The researchers demonstrated this control by modifying the nanostar designs and watching how the condensates responded. By changing the structure of the RNA, they could shift where droplets formed within the cell and alter their size and composition. This level of programmability opens possibilities that were difficult or impossible with earlier approaches. As the technology matures, these artificial organelles could be engineered to perform specialized biological functions—delivering drugs to specific cellular locations, regulating gene expression, or organizing chemical reactions that don't occur naturally in cells.
The work involved researchers across multiple UCLA departments and was supported by the National Science Foundation, the Alfred P. Sloan Foundation, and the National Institutes of Health. The UCLA Technology Development Group has already filed a patent application. What began as a fundamental question about how to program matter at the molecular scale now points toward practical applications in nanomedicine, genetics, and cell engineering—a frontier where the boundary between biology and engineering continues to blur.
Citas Notables
By using RNA as a building material, we can create customizable compartments inside cells while using fewer cellular resources than protein-based approaches.— Elisa Franco, study lead and professor of mechanical and aerospace engineering and bioengineering at UCLA
We can control how and where these RNA droplets form and what they attract, effectively creating new, temporary rooms inside the cell furnished with selected molecular tools.— Shiyi Li, study first author and bioengineering doctoral candidate
La Conversación del Hearth Otra perspectiva de la historia
Why does it matter that these are made from RNA rather than protein?
RNA is predictable in a way that proteins aren't. Proteins fold and interact based on complex chemistry that's hard to control. RNA follows simple base-pairing rules—A binds to U, G binds to C—so you can design exactly what you want and know it will assemble the way you planned.
But couldn't you just use natural organelles that already exist in cells?
Natural organelles are fixed structures. They do what they evolved to do. These artificial ones are programmable—you can change their properties on the fly, move them to different parts of the cell, make them recruit different molecules. You're not limited by evolution.
What's the practical use case that excites you most?
Nanomedicine, probably. Imagine delivering a drug directly to a tumor cell and having it activate only inside a synthetic organelle you've engineered there. You get precision without harming healthy cells. That's not possible with current tools.
How close are we to that actually working in a living organism?
This is still early. They've shown it works in cells in the lab. Getting it to work reliably in a whole organism, in a living body—that's years away. But the proof of concept is solid now.
What could go wrong?
Off-target effects. The RNA might interact with things it shouldn't. The immune system might recognize it as foreign. You'd need to engineer around those problems. But those are engineering challenges, not fundamental barriers.