Researchers develop nano- pillars to breach cell nuclei without damage
Researchers at the University of California San Diego have developed an innovative nanotechnology that can create temporary openings in the nuclear membrane of living cells without damaging the cell’s outer structure. This breakthrough, published in the journal Advanced Functional Materials [1], could revolutionize gene therapy and drug delivery methods by providing direct access to the cell’s command centre.
The nucleus, which houses a cell’s genetic material, is protected by a highly selective membrane that tightly regulates the entry and exit of molecules. This stringent barrier has long posed a significant challenge for scientists and clinicians aiming to deliver therapeutic agents or genetic material directly into the nucleus.
“It’s not easy to get anything into the nucleus,” said Zeinab Jahed, professor in the Aiiso Yufeng Li Family Department of Chemical and Nano Engineering at UC San Diego and senior author of the study. “Drug and gene delivery through the nuclear membrane has long been an immense challenge.”
A delicate approach
Traditional methods for accessing the nucleus often involve using microscopic needles to physically puncture both the cell membrane and the nuclear envelope. However, these techniques are invasive and limited in their scalability, making them unsuitable for widespread clinical applications.
The UC San Diego team, led by Jahed and PhD student Ali Sarikhani, took a radically different approach. They engineered an array of nanopillars – cylindrical structures measuring just nanometres in diameter – that can induce the nuclear membrane to temporarily open without compromising the integrity of the cell’s outer membrane.
When cells are placed on top of these nanopillars, the nucleus naturally moulds itself around the tiny structures. This induced curvature causes minuscule, self-sealing openings to form in the nuclear membrane, creating transient gateways into the nucleus.
“We’ve developed a tool that can easily create a gateway into the nucleus,” Jahed explained. “This is exciting because we can selectively create these tiny breaches in the nuclear membrane to access the nucleus directly, while leaving the rest of the cell intact.”
SEM image of a cell sitting on top of the nanopillar array. (Ali Sarikhani)
Proof of concept
To demonstrate the effectiveness of their technique, the researchers conducted experiments using cells containing fluorescent dyes within their nuclei. When placed on the nanopillar array, the dye was observed leaking from the nucleus into the surrounding cytoplasm but remained confined within the cell. This crucial observation confirmed that only the nuclear membrane had been breached, leaving the cell’s outer membrane undamaged.
Importantly, the team observed this effect across various cell types, including epithelial cells, cardiomyocytes, and fibroblasts. This versatility suggests broad potential applications in different areas of medicine and cell biology.
Size matters
The researchers discovered that the dimensions of the nanopillars play a critical role in the effectiveness of nuclear membrane breaching.
By using isotropic wet etching techniques, they were able to create nanopillars of different sizes while keeping other factors constant.
Interestingly, smaller nanopillars (height, 3.18 ± 0.033 μm; diameter, 0.515 ± 0.03 μm) were found to be significantly more effective at inducing nuclear membrane openings compared to larger ones (height, 4.7 ± 0.02 μm; diameter, 1.30 ± 0.01 μm). The percentage of cells exhibiting nuclear membrane breaches increased dramatically from 12% with larger nanopillars to 78% with the smaller variants.
The team’s analysis revealed that while larger nanopillars caused deeper indentations in the nuclear membrane, it was the higher curvature induced by smaller nanopillars that more significantly contributed to the formation of membrane openings. This finding highlights the importance of fine-tuning the nanopillar geometry to optimise the technique’s effectiveness.
Temporal dynamics and repair mechanisms
Another crucial aspect of the study was the investigation of the temporal dynamics of these nuclear membrane openings. The researchers found that a small percentage of cells exhibited openings as early as 1 hour after being placed on the nanopillars, with the proportion increasing to about 20% after 5 hours.
Importantly, the nuclear membrane breaches were found to be transient, with cells able to repair the openings within approximately 1.5 hours. This self-repair mechanism involves the recruitment of specialised protein complexes known as ESCRT-III (Endosomal Sorting Complexes Required for Transport), which help seal the membrane breaches.
Future implications
The development of this nanopillar technology opens up exciting possibilities in the field of gene therapy and precision medicine. By providing a non-invasive method to access the cell nucleus, it could enable more efficient delivery of genetic material or therapeutic agents directly to where they are needed most.
However, the researchers emphasise that further investigation is needed to fully understand the mechanisms behind this effect and to optimise the platform for clinical use. “Understanding these details will be key to optimising the platform for clinical use and ensuring that it is both safe and effective for delivering genetic material into the nucleus,” said Jahed.
As research in this area progresses, it is conceivable that nanopillar arrays could become a valuable tool in the development of new treatments for genetic disorders, cancer, and other diseases that require precise manipulation of cellular genetics.
This groundbreaking work not only demonstrates the power of nanotechnology in overcoming long-standing biological barriers but also highlights the importance of interdisciplinary collaboration in driving medical innovation forward.
Reference:
1. Sarikhani, E., Patel, V., Li, Z., et. al. (2024). Engineered Nanotopographies Induce Transient Openings in the Nuclear Membrane. Advanced Functional Materials, 2410035. https://doi.org/10.1002/adfm.202410035
