Cell therapy makers use antibodies and cytokines to prime—or activate—T cells to receive genetic material and grow. While this approach works for low-volume production, industry needs more efficient methods for large-scale manufacturing.

In cell biology the term “activation” describes the process of preparing naïve T cells for differentiation and growth. In nature, activation occurs when an antigen is presented to the cell, often by a dendritic cell (DC). Therapy developers also activate cells. However, rather than co-culturing them with dendritic cells, it is more common to use antibody and cytokine-based protocols to make T cells ready for transduction or proliferation.

The difficulty is that current activation methods were developed for use in the laboratory rather than for commercial-scale production, says April Kloxin, PhD, a professor at the University of Delaware.

“Activation and transduction of T cells often is performed by mixing an activating agent and virus with T cells in static lab-scale cultures during cell therapy production, where a large amount of virus is required,” she notes. Biomanufacturing platforms are needed for efficient activation and transduction and that can be scaled up for making cell therapies more accessible and broadly applicable for a range of indications.”

Bio-inspired polymers

With this in mind, Kloxin and colleagues took a different approach. Rather than focusing on just the interactions, they tried to make the manufacturing line more like the environment in which T cells are activated in nature using “bio-inspired” polymers.

“The bio-inspired soft materials are thin, hydrated coatings formed on commercially available membranes and are built with biocompatible polymers that are modified with bioactive proteins,” she explains. “The materials are designed to mimic key aspects of the environment that T cells experience in the body to promote and enhance T-cell activation and desired functions relevant to cell therapies.

“Specifically, these materials have a ‘stiffness’ like that of the lymph nodes where T cells natively are activated and display proteins natively presented by complementary cells in the lymph nodes that promote T cell binding and activation. The properties of the materials are ‘tunable’ and can be tailored based on the cell therapy application of interest. The material also can be dissolved with the application of specific wavelengths of light for harvesting cells or other products on the membrane if desired.”

According to Kloxin, cells activated in the bio-inspired materials system demonstrated a more robust response than those activated on tissue culture plates. In addition, a greater proportion of the activated cells were of a phenotype relevant for cell therapy applications.

“Our system also allows us to tackle challenges associated with low transduction of cells, which can limit the number of functional engineered cells obtained and require large quantities of virus to achieve high transduction,” he says.

“Membranes coated with the bio-inspired soft materials are easily incorporated in existing membrane-based flow devices for concentrating cells and viruses under flow at the material surface for enhancing transduction. Traditionally, these membrane-based flow devices are often used in downstream purification of protein products. By integrating hydrogel-coated membranes in these devices and using flow rates relevant for cells in culture, we were able to generate three times more engineered T cells compared to static controls with virus and cells in a well plate.”

The project is being supported by an award from the National Institute for Innovation in Manufacturing Biopharmaceuticals (NIIMBL) with financial assistance from the U.S. Department of Commerce and National Institute of Standards and Technology.

The next steps are collaborative, according to Kloxin, who says, “We are delighted to be working with a membrane device manufacturer as part of NIIMBL. While the hydrogel-coated membranes are not yet available commercially, we continue to work on honing and demonstrating the utility of the technology in manufacturing of cell therapies for future commercialization.