The biggest problem with putting living cells inside your body to make drugs is that the cells need oxygen — and subcutaneous tissue, where you'd implant them, doesn't have much to spare. Pack too many cells together and they suffocate before they can deliver a meaningful dose. A team from Northwestern University, Rice University, and Carnegie Mellon University thinks it has solved that. They built a wireless, fully implantable device called HOBIT — short for Hybrid Oxygenation Bioelectronics System for Implanted Therapy — that houses engineered cells in a two-stage encapsulation system and keeps them alive with an on-board oxygen generator that splits water using an iridium oxide electrocatalytic surface. No external tubes. No refills. Just a small device, about the size of a folded stick of gum, working away under the skin.
The results, published March 27 in Device, a Cell Press journal, show the approach working in rats: cell densities roughly six times higher than conventional unoxygenated implants, with about 65 percent of cells still viable at 30 days compared to roughly 20 percent in controls. In animals with devices that lacked oxygenation, the biologics with shorter half-lives were undetectable by day 7. Exenatide, a first-generation GLP-1 drug, has a half-life of roughly 2.5 hours — too short to register in an oxygen-starved implant. HOBIT kept producing it.
The bigger novelty is what those cells were making. The team engineered them to simultaneously produce three different biologics — an anti-HIV antibody, a GLP-1-like peptide used to treat type 2 diabetes, and leptin, a hormone that regulates appetite and metabolism. Multi-drug delivery from a single implant is the real step forward here. These molecules have entirely different half-lives and mechanisms, and getting them all out of one device in controlled proportions is what separates this from a more conventional combination therapy.
"The fact that you can independently tune each component — the oxygen generator, the cell encapsulation, the drug release kinetics — and then integrate them into something you can actually implant is the engineering contribution," said Jonathan Rivnay, a bioengineer at Northwestern University and one of three co-lead investigators on the project. Omid Veiseh, a bioengineer at Rice University, and Tzahi Cohen-Karni, a biomedical engineer at Carnegie Mellon University, co-led the work. Chris Wright, a Rice PhD student, is the first author.
The oxygen generator uses electricity from an onboard battery to split water present in surrounding tissue, producing oxygen locally without generating harmful byproducts. The engineered cells are first microencapsulated in alginate hydrogel beads — a calcium-alginate matrix that protects them from the immune system — and then loaded into a semipermeable membrane chamber that allows secreted biologics to diffuse out while keeping host cells at bay. This two-stage approach is what allows the higher cell density: without local oxygen, packing cells that tightly would be fatal.
The researchers tested the device in rats for proof of multi-drug production. A separate experiment in a 7-year-old male cynomolgus macaque confirmed that the device — without therapeutic cells — could be safely implanted and removed after a month with no major health risks or serious immune response. That's a relevant data point for the surgical and immunological risk profile, though it says nothing about long-term function with live cells inside.
The funding tells you where this came from. The work was supported by Breakthrough T1D, formerly known as JDRF, the type 1 diabetes research foundation — which explains the GLP-1 interest. But the larger financial backing is a DARPA cooperative agreement worth up to $33 million over four-and-a-half years, part of a program called NTRAIN (Normalizing Timing of Rhythms Across Internal Networks of Circadian Clocks), itself under the broader ADAPTER program at the Pentagon's research arm. ADAPTER was specifically created to develop implantable systems that can modulate warfighter physiology — sleep-wake cycles, stress response, infection exposure. The living pharmacy angle isn't primarily about diabetes or HIV. It's about giving soldiers a device that produces therapeutics on demand without a supply chain.
Veiseh is also director of the Rice Biotech Launch Pad, an accelerator focused on translating university health and medical technology discoveries into commercial products. That's the bridge from DARPA paper to actual clinic — and it's where timelines get slippery.
The oxygenation problem HOBIT addresses is not unique to this system. Any encapsulated cell therapy sitting in poorly vascularized tissue faces the same survival constraint, which is part of why the field has struggled to move beyond proof-of-concept. If the on-board oxygenation approach scales, it could be licensed broadly rather than being specific to this device.
But this is still rat work wearing a lab coat. Substantial animal testing remains before any human trial, and the timeline for that is not clear. The long-term immune response to the implant, the durability of the oxygen-generating components, and the regulatory path for a living cell factory producing multiple biologics simultaneously are all open questions. FDA would effectively be evaluating a drug manufacturing process embedded in a patient, which is not a framework that currently exists.
The technical pieces — microencapsulation, electrocatalytic oxygen generation, engineered therapeutic cells — are individually not new. What's novel is putting them together in a fully integrated wireless system small enough to implant, with enough cell density to be clinically relevant. Whether that integration holds up at larger scale, in larger animals, over longer periods, is what the next several years of work will determine.
The paper is "Design of a wireless, fully implantable platform for in-situ oxygenization of encapsulated cell therapies," published in Device (DOI: 10.1016/j.device.2026.101106).
