Background

Cell therapy investigations rely on ex vivo operations to adequately preserve the viability and functionality of the cell products prior to in vivo administration (Li et al., 2019). Process development for cell products requires standard operations with controlled systems, which should be monitored throughout the process of end-to-end manufacturing. Clinical laboratories routinely cryopreserve cells using cryopreservation solutions and operating conditions that need to be tightly controlled and amenable to the cell type for optimal cell viability and yield. The use of automated equipment that combines multiple manufacturing processes, such as fill-finish systems and controlled-rate freezers, can offer several advantages over manual operations including automation, better control of processing, and efficiency, thereby avoiding potential compromises to the viability and yield of cell products (van der Walle et al., 2021). Together, these systems can be employed and programmed to optimize the operations for cell cryopreservation at end-stage manufacturing as well as starting materials upstream of manufacturing.

Multiple cell types have been evaluated as cell therapies for clinical use to treat a broad spectrum of clinical indications. Depending on the cell type, specific reagents and operating conditions need to be considered for ex vivo manufacturing expansions to generate high yields for therapeutic dosages (Galipeau and Sensébé, 2018; Pigeau et al., 2018). For example, anchorage-dependent cells require adherence to substrates (e.g., plastic cultureware, microcarriers) to proliferate, whereas other cells proliferate in suspension without substrates (Merten, 2015; Cuesta-Gomez et al., 2023). Typically, cell therapy products are initially isolated from tissues or collected by apheresis from individuals and subsequently undergo various process development procedures to isolate, expand (i.e., proliferate), and harvest the cells (Bunnell et al., 2008; Palen et al., 2021). Herein, procedures that are applicable for both adherent (i.e., mesenchymal stromal cells, MSCs) and apheresis-derived suspension cells (i.e., peripheral blood mononuclear cells, PBMCs) were described to demonstrate how to prepare the cells (e.g., culture and harvest MSCs, isolated PBMCs) and subsequently execute automated and controlled process development procedures that are amenable to cell therapy product manufacturing.

The Finia^® Fill and Finish System (Terumo Blood and Cell Technologies) is an automated, closed system that offers temperature-controlled processing for formulation and aliquoting of liquids, including cell suspensions, in preparation for cryopreservation (Sethi and Cunningham, 2021; Algorri et al., 2022). The system mixes and cools up to three materials (e.g., cells, buffers, cryopreservation solutions) to a specified temperature. The system offers flexible procedure programming to allow the user to define workstream needs, from simple aliquoting of a cell source to the stepwise cooling of cell solution, a relevant buffer, and a cryopreservation solution of choice. The final cell product is then aliquoted into individual product bags and automatically sealed. The single-use disposable set is composed of product bags appropriate for freezing, thawing, and administration in the clinic, and a quality control bag for testing (Sethi and Cunningham, 2020; Cunningham et al., 2022). The disposable set is offered in two volume configurations, allowing for the freezing of volumes from 10 to 70 mL per bag. The Finia system is governed by the cell processing application (CPA), which is a secure server-based software (i.e., protected from access by unauthorized individuals) for procedure management and record keeping, capable of tracking performance and protocol development for current Good Manufacturing Practices (cGMP) compliance.

The Finia system and controlled-rate freezer are two separate automated systems that together provide a closed system workflow, which has several advantages over common cell culture practices, including a reproducible cryopreservation procedure with >90% post-thaw cell viability and the prevention of risks related to contamination and operator error. In addition, product bags can store considerably more cells than cryovials (Sethi and Cunningham, 2021). Sethi and Cunningham performed studies to compare a robust manual process to the Finia system (automated process) using T cells and found that the targeted product volumes were more accurate using the automated processing, and cell viability (comparing pre-formulation, post-formulation, and post-thaw) was comparable between the two processes (Sethi and Cunningham, 2021). Cell therapy manufacturing can be further automated by the use of programmable, multi-step-controlled rate freezers, which can standardize and record freezing procedures (Meneghel et al., 2020). Based on these previous studies, our group has implemented streamlined methods for using the Finia system and a controlled-rate freezer for processing and cryopreservation of both adherent and suspension cell types commonly used in cell manufacturing as cell therapy products or as starting materials, respectively. Terumo Blood and Cell Technologies has performed internal testing on the Finia system to demonstrate it can be used for both adherent and suspension cells (data on file). Furthermore, the use of the Finia system in a workstream for a homogenous population of T cells was recently reported (Cunningham et al., 2022). This is the first published report on the use of the Finia system with adherent cells (i.e., MSCs) as well as heterogeneous suspension cells (i.e., PBMCs). Furthermore, we provide quality control results (based on cell count, viability, and phenotyping), troubleshooting guidance, and considerations for GMP and Good Laboratory Practice (GLP) compliance with application to automated and controlled process development procedures amenable to cell therapy product manufacturing.