Antibodies can now be re-engineered to work inside cells, not just on their surface, using AI-guided redesign of their binding fragments so they remain stable in the intracellular environment and can directly bind disease-driving proteins such as those involved in neurodegenerative disorders.
ACCESS Health International
Antibody-based drugs form a crucial part of modern medicine. Historically, the interior of cells was inaccessible to these drugs, but advancements are starting to change this. This article is the first in a series exploring how antibodies can target diseases both inside and outside cells.
Antibodies are designed to recognize specific structures on the surfaces of cells, viruses, and bacteria, allowing for precise disease targeting. However, their effectiveness has traditionally been confined to cell surfaces. The goal has been to harness this precision inside cells, where many diseases originate. A new study offers a solution, paving the way for treatments targeting diseases like Alzheimer’s, Parkinson’s, and motor neuron disease.
Antibodies are made from protein components that form structures capable of targeting precise biological markers. Produced within cells, they are secreted to bind with specific structures on pathogens or affected cells. While effective outside cells, they struggle to function internally, where disease-causing processes, such as harmful protein accumulation in neurodegenerative diseases, occur. Attempts to shrink antibodies into fragments that can work inside cells have faced challenges, as these fragments often lose their stability and function once inside.
The breakthrough involves reengineering antibodies to use only their target-binding fragments, which can function inside cells. This requires adapting them to the intracellular environment, where electrical charge influences stability and aggregation. Traditional antibody fragments tend to clump together inside cells due to their charge, but redesigning them to suit the intracellular environment produced over 600 stable intracellular antibody fragments from existing antibodies. These redesigned molecules can recognize disease-related targets within living cells, creating a new foundation for therapies addressing proteins linked to neurodegenerative diseases.
Redesigning Antibodies
Antibodies are naturally suited for functioning outside cells, but inside, the environment can cause them to misfold or degrade before reaching their targets. A significant challenge is the imbalance of electrical charge, which leads to clumping inside cells. By adjusting charge distribution, redesigned fragments remain stable and functional. Using artificial intelligence, existing antibodies were modified to maintain target recognition while adapting to intracellular conditions. This approach focuses on the behavior of antibodies inside cells rather than altering their binding targets, creating a modular platform applicable to many antibodies. Hundreds of antibodies have been converted into intracellular versions, enabling quick adaptation for new purposes.
A New Route for Neurodegenerative Disease
The most immediate impact could be seen in diseases driven by protein misfolding and toxic protein buildup within cells. In diseases like Alzheimer’s, Parkinson’s, Huntington’s, and motor neuron disease, abnormal proteins accumulate and disrupt cellular function. These changes often occur inside cells, making them difficult to target with traditional antibody therapies.
Intracellular antibody fragments provide a way to directly target these harmful proteins at the site of damage. The platform preserves the recognition properties of original antibodies, allowing for precise differentiation between normal and abnormal protein states. This precision is crucial in neurodegenerative diseases, where incorrect targeting can disrupt normal cellular function. The approach complements emerging gene-based delivery technologies, enabling cells to produce the antibody fragments themselves, paving the way for targeted intracellular treatments for diseases with limited effective options.
The AI Advantage
Artificial intelligence is central to this large-scale development. After identifying the design rule regarding charge, AI-based protein redesign enhanced stability while preserving target recognition, allowing hundreds of antibody sequences to be converted into intracellular-ready formats. This introduces a repeatable engineering framework for redesigning biologics.
This modular method holds considerable value in biotechnology, with potential applications across multiple disease areas. A system converting existing antibodies into intracellular tools could extend beyond neurodegenerative diseases to include cancer biology, inflammatory disorders, and rare genetic conditions.
Looking Ahead
Expanding the operational scope of antibodies broadens the range of biological processes that can be targeted. Molecules previously unable to penetrate cells can now be repurposed as intracellular therapeutics and research tools. In a field where time, specificity, and scalability are crucial, this development could have significant implications.
Future biologic therapies may extend beyond the cell surface. With AI-guided redesign, antibodies can now focus on molecular events at the core of some of the world’s most serious diseases.
This work is part of a series showcasing the development of modern antibody strategies to enhance immune responses, with potential applications across diverse diseases and therapeutic areas.
