Scientists have long dreamed of fixing genetic diseases by simply swapping out broken genes with functional ones. Yet despite decades of effort, few gene therapies have made it across the FDA finish line. One reason? Controlling how much of a new gene gets expressed inside the cell has proven surprisingly tricky. Now, researchers at MIT may have found a way to solve that problem, offering a new "circuit" approach that could one day make gene therapies safer, more effective, and easier to manufacture. Their work, published today in Cell Systems, points to a future where gene therapy is not just about delivering a missing gene—but delivering it just right.
Many diseases, from hemophilia to sickle cell anemia, stem from a single missing or defective gene. In theory, replacing that gene could offer a cure. But gene therapy’s success has been hampered by the difficulty of regulating gene expression once the genetic payload is delivered. Too little expression and the therapy fails; too much, and it risks toxic side effects.
"Simple overexpression of that payload can result in a really wide range of expression levels in the target genes as they take up different numbers of copies of those genes or just have different expression levels," explains Kasey Love, lead author of the new study and a graduate student at MIT. "If it's not expressing enough, that defeats the purpose of the therapy. But on the other hand, expressing at too high levels is also a problem, as that payload can be toxic."
The MIT team, led by Katie Galloway, the W.M. Keck Career Development Professor of Biomedical Engineering and Chemical Engineering, tackled the issue by engineering a novel control circuit called ComMAND—Compact microRNA-mediated attenuator of noise and dosage. Their system acts like a smart regulator, ensuring that genes operate within a Goldilocks zone: not too little, not too much.
Katie will also be at SynBioBeta: The Global Synthetic Biology Conference next week, presenting data from her laboratory in a session entitled “AI 'Cheat Codes' Speed Therapeutic Cell Creation via Transcription Factors.”
At the heart of ComMAND is a clever use of an incoherent feedforward loop (IFFL), a natural biological pattern where a gene’s activation simultaneously triggers a built-in brake. In this case, the researchers engineered a microRNA strand to be embedded within the therapeutic gene itself. When the gene is turned on, it automatically produces both the desired protein and the microRNA that limits its overproduction—keeping expression levels tightly under control.
“Other people have developed microRNA-based incoherent feedforward loops, but what Kasey has done is put it all on a single transcript, and she showed that this gives the best possible control when you have variable delivery to cells,” says Galloway.
To put their circuit to the test, the team used ComMAND to deliver two genes implicated in serious genetic diseases: FXN (defective in Friedreich’s ataxia) and Fmr1 (mutated in Fragile X syndrome). In human cells, they tuned gene expression to about eight times the normal level—a significant boost, but far below the unsafe 50-fold increase seen without ComMAND.
The team also validated the system in rat neurons, mouse fibroblasts, and human T-cells, using a fluorescent protein as a proxy to measure expression levels. Across all cell types, ComMAND consistently delivered more stable and safer gene expression compared to conventional methods.
In addition to better control, the circuit’s streamlined design means it fits neatly into a single delivery vehicle, like a lentivirus or an adeno-associated virus—the workhorses of gene therapy—potentially making future treatments more scalable and easier to manufacture.
The next frontier, according to the researchers, is applying ComMAND in live models. They aim to fine-tune expression levels even further to restore normal function and reverse signs of disease.
"There's probably some tuning that would need to be done to the expression levels, but we understand some of those design principles, so if we needed to tune the levels up or down, I think we'd know potentially how to go about that," says Love.
The team believes the technology could eventually be adapted to tackle a range of rare genetic diseases, including Rett syndrome, muscular dystrophy, and spinal muscular atrophy—disorders where patient populations are small and funding for research is limited.
“The challenge with a lot of those is they're also rare diseases, so you don't have large patient populations,” Galloway notes. “We're trying to build out these tools that are robust so people can figure out how to do the tuning, because the patient populations are so small and there isn't a lot of funding for solving some of these disorders.”
Lorem ipsum dolor sit amet, consectetur adip elit. Donec posuere dolor massa, pellentesque aliquam nisl facilisis sed.
Scientists have long dreamed of fixing genetic diseases by simply swapping out broken genes with functional ones. Yet despite decades of effort, few gene therapies have made it across the FDA finish line. One reason? Controlling how much of a new gene gets expressed inside the cell has proven surprisingly tricky. Now, researchers at MIT may have found a way to solve that problem, offering a new "circuit" approach that could one day make gene therapies safer, more effective, and easier to manufacture. Their work, published today in Cell Systems, points to a future where gene therapy is not just about delivering a missing gene—but delivering it just right.
Many diseases, from hemophilia to sickle cell anemia, stem from a single missing or defective gene. In theory, replacing that gene could offer a cure. But gene therapy’s success has been hampered by the difficulty of regulating gene expression once the genetic payload is delivered. Too little expression and the therapy fails; too much, and it risks toxic side effects.
"Simple overexpression of that payload can result in a really wide range of expression levels in the target genes as they take up different numbers of copies of those genes or just have different expression levels," explains Kasey Love, lead author of the new study and a graduate student at MIT. "If it's not expressing enough, that defeats the purpose of the therapy. But on the other hand, expressing at too high levels is also a problem, as that payload can be toxic."
The MIT team, led by Katie Galloway, the W.M. Keck Career Development Professor of Biomedical Engineering and Chemical Engineering, tackled the issue by engineering a novel control circuit called ComMAND—Compact microRNA-mediated attenuator of noise and dosage. Their system acts like a smart regulator, ensuring that genes operate within a Goldilocks zone: not too little, not too much.
Katie will also be at SynBioBeta: The Global Synthetic Biology Conference next week, presenting data from her laboratory in a session entitled “AI 'Cheat Codes' Speed Therapeutic Cell Creation via Transcription Factors.”
At the heart of ComMAND is a clever use of an incoherent feedforward loop (IFFL), a natural biological pattern where a gene’s activation simultaneously triggers a built-in brake. In this case, the researchers engineered a microRNA strand to be embedded within the therapeutic gene itself. When the gene is turned on, it automatically produces both the desired protein and the microRNA that limits its overproduction—keeping expression levels tightly under control.
“Other people have developed microRNA-based incoherent feedforward loops, but what Kasey has done is put it all on a single transcript, and she showed that this gives the best possible control when you have variable delivery to cells,” says Galloway.
To put their circuit to the test, the team used ComMAND to deliver two genes implicated in serious genetic diseases: FXN (defective in Friedreich’s ataxia) and Fmr1 (mutated in Fragile X syndrome). In human cells, they tuned gene expression to about eight times the normal level—a significant boost, but far below the unsafe 50-fold increase seen without ComMAND.
The team also validated the system in rat neurons, mouse fibroblasts, and human T-cells, using a fluorescent protein as a proxy to measure expression levels. Across all cell types, ComMAND consistently delivered more stable and safer gene expression compared to conventional methods.
In addition to better control, the circuit’s streamlined design means it fits neatly into a single delivery vehicle, like a lentivirus or an adeno-associated virus—the workhorses of gene therapy—potentially making future treatments more scalable and easier to manufacture.
The next frontier, according to the researchers, is applying ComMAND in live models. They aim to fine-tune expression levels even further to restore normal function and reverse signs of disease.
"There's probably some tuning that would need to be done to the expression levels, but we understand some of those design principles, so if we needed to tune the levels up or down, I think we'd know potentially how to go about that," says Love.
The team believes the technology could eventually be adapted to tackle a range of rare genetic diseases, including Rett syndrome, muscular dystrophy, and spinal muscular atrophy—disorders where patient populations are small and funding for research is limited.
“The challenge with a lot of those is they're also rare diseases, so you don't have large patient populations,” Galloway notes. “We're trying to build out these tools that are robust so people can figure out how to do the tuning, because the patient populations are so small and there isn't a lot of funding for solving some of these disorders.”
Lorem ipsum dolor sit amet, consectetur adip elit. Donec posuere dolor massa, pellentesque aliquam nisl facilisis sed.
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