Rice University researchers, along with collaborators from Carnegie Mellon University and Northwestern University, announced on Mar. 27 the successful integration of multiple solutions into a single device designed to house living cells that produce drugs within the body. The Hybrid Oxygenation Bioelectronics system for Implanted Therapy, or HOBIT, is intended to protect a high number of therapeutic cells from the immune system while providing them with essential oxygen and nutrients.
Implanting living cells as long-term drug producers could transform treatment for many diseases. However, maintaining enough viable cells in a small implantable space has been challenging due to limited oxygen supply under the skin, where such devices are typically placed. "When they are packed into dense clusters, cells compete with each other for oxygen," said Chris Wright, a Rice Ph.D. student and first author on the study published in Device. "Under the skin, there simply is not enough local supply to support the number of cells you would need for a clinically meaningful dose."
To address this issue, HOBIT incorporates an electrocatalytic oxygenator powered by an onboard battery that splits water in surrounding tissue to generate local oxygen without harmful byproducts. Tzahi Cohen-Karni of Carnegie Mellon University said: "Our collaborative efforts are highly unique, a combination of energy research, with bioengineering - toward efficiently providing oxygen to the cell factories." The latest version integrates all components into a wireless implantable system that can be remotely adjusted.
Jonathan Rivnay of Northwestern University explained: "We are producing oxygen directly where the cells need it... Cell densities in HOBIT were roughly six times higher than conventional unoxygenated encapsulation approaches." The device also uses two-stage encapsulation—microencapsulating engineered cells in alginate hydrogel beads before placing them inside a semipermeable chamber—to allow nutrient flow while protecting against immune attack.
Omid Veiseh of Rice University said: "In addition to solving the oxygenation and cell density problem, the HOBIT platform is also proof of concept that cell factories can be engineered to produce multiple biologic molecules simultaneously." Testing in rats showed sustained production levels over 30 days when using HOBIT compared with control devices; about 65% of implanted cells remained viable versus roughly 20% without added oxygenation.
The team plans further studies using larger animals and disease-specific applications such as diabetes therapy. Veiseh concluded: "Many groups are working to make drugs last longer or require less intensive dosing regimens... Our goal is to provide the engineering framework that makes that feasible."
