Flanders, J. A. | Search bioRxiv

bioRxiv2026

Miniaturized subcutaneous cellular implants for sustained therapeutic protein delivery in resource-limited settings

Cell encapsulation offers a promising strategy for sustained therapeutic protein delivery, obviating the need for repeated injections. Among potential implantation sites, the subcutaneous space is particularly attractive for its accessibility and amenability to minimally invasive procedures. However, performance of subcutaneous devices reported to date has been limited due to various challenges including foreign body response (FBR) and inadequate mass transfer. Moreover, typical encapsulation devices require surgeries for implantation and retrieval, limiting their potential use in resource-limited settings. Here we present a miniaturized cell encapsulation platform comprising cells engineered to produce therapeutic proteins and an FBR-mitigating zwitterionic polyurethane nanofibrous membrane, in a thin cylindrical form factor compatible with applicator-based minimally invasive implantation and retrieval. Clonal mesenchymal stromal cells engineered to produce PGT121, a broadly neutralizing anti-HIV-1 antibody, were encapsulated and inserted subcutaneously, achieving long-term cell survival and sustained serum PGT121 concentrations for up to 36 weeks across multiple murine models. Cell-loaded devices retained therapeutic function after cryopreservation, supporting their potential use as an off-the-shelf product that can be centrally manufactured and implanted on-site without specialized infrastructure. The custom-designed applicator-based implantation and minimally invasive retrieval procedures were demonstrated in a more clinically relevant minipig model. These mini-"cellular factories" represent a translatable strategy for sustained delivery of biologic drugs in resource-limited settings. One Sentence SummaryAn insertable and retrievable mini cellular construct enables sustained protein delivery, supporting its potential use in resource-limited settings.

bioengineering↗

bioRxiv2025

A Continuously Oxygenated Macroencapsulation System Enables High-Density Packing and Delivery of Insulin-Secreting Cells

The encapsulation of insulin-secreting cells within immuno-protective systems holds significant promise for curative treatment of type 1 diabetes without immunosuppression. A major challenge, however, remains the inadequate oxygen tension within the encapsulation systems, which compromises the survival and function of encapsulated cells and necessitates low packing density and impractically large systems to deliver a curative cell mass. In this study, we present a novel cell encapsulation system capable of generating oxygen via the electrolysis of tissue moisture to provide a continuous oxygen supply to densely packed insulin-secreting cells. Our system comprises a miniaturized implantable electrochemical oxygen generator (iEOG) and a scalable cylindrical cell encapsulation pouch, designed in a linear configuration to facilitate minimally invasive implantation and retrieval. The oxygen generation from the system was shown to be precisely controlled, stable, and capable of supporting clinically relevant doses of pancreatic islets. In vitro studies demonstrated that the oxygenated system effectively maintained the viability and function of insulinoma cell aggregates and human pancreatic islets at densities of 60,000 islet equivalents per mL (IEQ/mL) or 4,200 IEQ/cm{superscript 2} under a hypoxic cell culture condition (1% O ). In an allogeneic rat model, the oxygenated systems containing pancreatic islets implanted into the poorly vascularized but clinically attractive subcutaneous space at a density of 60,000 IEQ/mL successfully reversed diabetes for up to about 3 months without the need for immunosuppression, while animals implanted with non-oxygenated systems remained diabetic. Most ([~] 90%) of the pancreatic islets encapsulated in the continuously oxygenated systems were found viable and functional upon retrieval. These findings suggest the feasibility of using continuous oxygenation to support insulin-secreting cells at high loading densities in subcutaneous space, enabling the development of an encapsulation system with clinically practical dimensions.

bioengineering↗