Microfluidic Device & Gene Therapy
A Dating App for Cells and Viruses: Microfluidic Device for Facilitating Viral Transduction for Gene Therapy
The Food and Drug Administration’s Center for Biologics Evaluation and Research has recently approved a host of products for cellular and gene therapy, as success rates for these therapies have steadily climbed. Novel treatments where a patient’s own cells are removed, genetically modified, and transplanted back are demonstrating tremendous success for previously incurable diseases. Modified viruses are the key to transferring specially engineered genes into cells, but creating these viral vectors is far from easy, quick, or economical.
“As gene therapy has seen more success in treating and curing disease in the past few years, the field is maturing. The problem now is a manufacturing issue,” says Wilbur Lam, MD, PhD, assistant professor of hematology and oncology at Emory and assistant professor of biomedical engineering at Georgia Tech. “If you really want to bring in patients on a large scale and treat them, you have to have the volume. You need these special viruses, but the process is really inefficient, and traditional methods use more virus than is necessary.”
Lentiviruses, a class of virus that includes HIV, are commonly used in these “friendly takeovers.” They naturally have the machinery to insert genetic material into many different types of cells to permanently modify the genome. The lentiviruses used for gene and cell therapies have been crippled so that they do not replicate within the host cell or cause harmful effects. After infection, the gene is integrated into the cell, and is able to start expressing the new proteins. In the case of gene or cell therapies, the protein expressed is one of the researcher’s choosing, which can disrupt or alter the course of a disease.
One of the key challenges in using lentiviral vectors is that they require large quantities and a high concentration of virus to ensure transfer into most cells. “Generating the lentiviral vectors used for gene therapy is expensive, which makes the application of lentiviruses for gene therapy cost-prohibitive for many,” says Lam.
Lam and post-doctoral scholar Reginald Tran have developed a prototype of a device that has been shown to boost efficiency many times over by bringing more virus into contact with more cells – all while using less virus overall. The microfluidic device—a transparent square about the size of a waffle— contains multiple layers, each with a series of tunnels barely thicker than the width of a hair that wind back upon themselves in a zigzag pattern. “This creates a larger surface area-to-volume ratio while minimizing the distance that the virus travels to reach a cell,” Tran says. ”The microchannels can also be lined with a particular reagent that helps the cells and virus stick, to make sure every cell gets infected.”
“You’re just trying to smush these things together,” says Lam. The device has ports through which the virus is inserted using a syringe, which in the future could be adapted into automated manufacturing processes. The new device not only increases efficiency but speeds things up as well. “The longer cells are kept outside of the body, the less likely they are to work, so you want to minimize the time,” says Lam.
The Lam lab’s microfluidic device especially improves the efficiency of lentiviral gene transfer when modifying common target cells like immune cells and hematopoietic stem cells, which normally have very low transduction efficiency.
They have tested the device with a variety of different viruses, but there are other (yet to be tested) applications that are possible. The device can be easily modified to accommodate all sorts of cell types and amounts ranging from a million mouse cells to a billion human cells. It can also be used to create induced pluripotent stem cells (iPSCs), to deliver RNAi therapies, to facilitate CRISPR-based gene editing, and to manufacture CAR-T cell therapies.
Small biopharmaceutical firms currently using viral approaches to make these specialized modified cells as therapies can, with current technology, treat only a handful of patients with their entire stock. “It’s a supply-chain manufacturing issue,” says Lam.
A lot of companies now trying to commercialize these novel therapeutics must acquire enough virus by investing several hundred million dollars into their own manufacturing, or they are stuck on waiting lists of up to a year to get into the queue of companies that specialize in virus manufacturing, Tran says: “It’s a bottleneck.” Compared with typical techniques, says Lam, “Reggie’s device could make it possible to save at least five times more patients than typical techniques, even while using less virus. The tech is there. Now we’re just looking for industry partners.”
How the device works is simple physics: it brings the cells and viruses close together in an orchestrated fashion. “Whereas they would typically just randomly bump into each other, you could look at this like a dating app for the virus to find its soulmate cell,” says Lam. “This is a very exciting place to be,” adds Tran. “This could be something that can make gene and cell therapy more affordable and accessible for people.”
The largest impact would be where the need is greatest: diseases of the blood, such as sickle cell and thalassemia. “This could be a way to cure those, to give new blood stem cells,” Lam says. “At the end of the day, you need a lot of modified cells.”
One of the most fun and rewarding parts of working with Lam and colleagues is seeing how they approach challenges, says Cliff Michaels, assistant director of licensing for Emory’s Office of Technology Transfer—in this case, the application of engineering principles to solve a very real problem in the world of viral gene transfer and cell therapies.
“What I love about this particular device is how many different ways it could be applied,” Michaels says. “Viral vectors aren’t the only way to modify or repair cells. In the future, you could see this being used to facilitate RNA or CRISPR approaches—basically, any time you want to modify cells outside of the patient and then use those cells to treat a patient.”
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