Cryopreserved hematopoietic stem/progenitor cells stability program-development, current status and recommendations: A brief report from the AABB-ISCT joint working group cellular therapy product stability project team.

BACKGROUND: The AABB-ISCT Joint Working Group Stability Project Team (SPT) was assigned to roadmap a path toward standardization of cryopreserved hematopoietic stem/progenitor cell (HSPC) stability programs. HSPC stability encompasses a broad scope of conditions including non-frozen ("fresh") and cryopreserved cell products, and varying methods for storage, thaw, and administration. This report assessed current practices and focused solely on cryopreserved HSPC cell therapy products to establish preliminary recommendations for a stability program roadmap. METHODS: A survey was prepared by the SPT and distributed to ISCT and AABB members. Survey results were summarized and recommendations were outlined based on the responses from the survey. This report highlights current practices for cryopreserved HSPC stability programs, including additional considerations and recommendations. RESULTS AND DISCUSSION: Eighty-two (82) centers worldwide participated in the survey. Survey results indicate variability across programs. HSPC stability depends on multiple factors within the processing facility (e.g., cryopreservation techniques, reagents used, and storage temperature) and independent variables (e.g., donor-related factors and starting material variability). While retention of hematopoietic engraftment potential is the primary goal for cryopreserved HSPC stability, engraftment results should not be used as the sole metric for stability programs. Based on the survey results, the SPT provides recommendations for consideration. CONCLUSIONS: The SPT recommendations for best practices are not intended to replace existing standards. The survey results emphasize the need for the community to optimize best practices and consider initiating collaborative projects to improve the standardization of cryopreserved HSPC stability programs for cell therapy products.

Cryopreserved hematopoietic stem/progenitor cells stability program-development, current status and recommendations: A brief report from the AABB-ISCT joint working group cellular therapy product stability project team.

BACKGROUND: The AABB-ISCT Joint Working Group Stability Project Team (SPT) was assigned to roadmap a path toward standardization of cryopreserved hematopoietic stem/progenitor cell (HSPC) stability programs. HSPC stability encompasses a broad scope of conditions including non-frozen ("fresh") and cryopreserved cell products, and varying methods for storage, thaw, and administration. This report assessed current practices and focused solely on cryopreserved HSPC cell therapy products to establish preliminary recommendations for a stability program roadmap. METHODS: A survey was prepared by the SPT and distributed to ISCT and AABB members. Survey results were summarized and recommendations were outlined based on the responses from the survey. This report highlights current practices for cryopreserved HSPC stability programs, including additional considerations and recommendations. RESULTS AND DISCUSSION: Eighty-two (82) centers worldwide participated in the survey. Survey results indicate variability across programs. HSPC stability depends on multiple factors within the processing facility (e.g., cryopreservation techniques, reagents used, and storage temperature) and independent variables (e.g., donor-related factors and starting material variability). While retention of hematopoietic engraftment potential is the primary goal for cryopreserved HSPC stability, engraftment results should not be used as the sole metric for stability programs. Based on the survey results, the SPT provides recommendations for consideration. CONCLUSIONS: The SPT recommendations for best practices are not intended to replace existing standards. The survey results emphasize the need for the community to optimize best practices and consider initiating collaborative projects to improve the standardization of cryopreserved HSPC stability programs for cell therapy products.

Clinical methods of cryopreservation for donor lymphocyte infusions vary in their ability to preserve functional T-cell subpopulations.

BACKGROUND: Cryopreserved donor lymphocyte infusion (DLI) products are manufactured and administered to treat relapse after allogeneic hematopoietic stem cell transplantation. Reported clinical responses to DLIs vary broadly, even within the same group of patients. While there is an implicit recognition of the fact that different manufacturing protocols may have specific effects on different cell types, cryopreservation protocols are frequently derived from our experience in the cryopreservation of stem cell products and do not account for the heterogeneous functional nature of DLI T-cell populations. Here, we report the results of a prospective, multicenter trial on the effect of four different cryopreservation solutions that were used to freeze DLIs compared to control DLIs that were refrigerated overnight. STUDY DESIGN AND METHODS: Cryopreserved postthawed and refrigerated specimens were analyzed side by side for their T-cell subpopulation content and viability, as well as T-cell proliferation, cytokine secretion, and cytotoxic activities. RESULTS: This study indicates that "homemade" 10% dimethyl sulfoxide (DMSO) results in reduced viability of different CD4+ T-cell populations, including T-helper, T-cytotoxic, and T-regulatory populations, and a decrease in their proliferative and cytotoxic response to immunologically relevant stimuli, while the use of solutions containing 5% DMSO with intracellular-like cryoprotectant stabilizers maintains T-cell function at levels similar to refrigerated control samples. CONCLUSION: This study has important implications in determining the best cryoprotectant solution for specific clinical applications in allogeneic immunotherapy.

Off the shelf cellular therapeutics: Factors to consider during cryopreservation and storage of human cells for clinical use.

The field of cellular therapeutics has immense potential, affording an exciting array of applications in unmet medical needs. One of several key issues is an emphasis on getting these therapies from bench to bedside without compromising safety and efficacy. The successful commercialization of cellular therapeutics will require many to extend the shelf-life of these therapies beyond shipping "fresh" at ambient or chilled temperatures for "just in time" infusion. Cryopreservation is an attractive option and offers potential advantages, such as storing and retaining patient samples in case of a relapse, banking large quantities of allogeneic cells for broader distribution and use and retaining testing samples for leukocyte antigen typing and matching. However, cryopreservation is only useful if cells can be reanimated to physiological life with negligible loss of viability and functionality. Also critical is the logistics of storing, processing and transporting cells in clinically appropriate packaging systems and storage devices consistent with quality and regulatory standards. Rationalized approaches to develop commercial-scale cell therapies require an efficient cryopreservation system that provides the ability to inventory standardized products with maximized shelf life for later on-demand distribution and use, as well as a method that is scientifically sound and optimized for the cell of interest. The objective of this review is to bridge this gap between the basic science of cryobiology and its application in this context by identifying several key aspects of cryopreservation science in a format that may be easily integrated into mainstream cell therapy manufacture.

Standardized cryopreservation of human primary cells.

Cryopreservation is the use of low temperatures to preserve structurally intact living cells. The cells that survive the thermodynamic journey from the 37 °C incubator to the -196 °C liquid nitrogen storage tank are free from the influences of time. Thus, cryopreservation is a critical component of cell culture and cell manufacturing protocols. Successful cryopreservation of human cells requires that the cells be derived from patient samples that are collected in a standardized manner, and carefully handled from blood draw through cell isolation. Furthermore, proper equipment must be in place to ensure consistency, reproducibility, and sterility. In addition, the correct choice and amount of cryoprotectant agent must be added at the correct temperature, and a controlled rate of freezing (most commonly 1 °C/min) must be applied prior to a standardized method of cryogenic storage. This appendix describes how human primary cells can be frozen for long-term storage and thawed for growth in a tissue culture vessel.

Cryopreservation of umbilical cord blood with a novel freezing solution that mimics intracellular ionic composition.

BACKGROUND: Cryopreservation protocols have remained relatively unchanged since the first umbilical cord blood banking program was established. This study evaluated the preservation efficacy of a novel intracellular-like cryopreservation solution (CryoStor, BioLife Solutions, Inc.), the rate of addition of two cryopreservation solutions to cord blood units (CBUs), and reduced final dimethyl sulfoxide (DMSO) concentration of 5%. STUDY DESIGN AND METHODS: Split-sample CBUs were cryopreserved with either an in-house 20% DMSO-based cryopreservation solution or CryoStor CS10 at a rate of 1 mL/min (n = 10; i.e., slow addition) or as a bolus injection (n = 6; i.e., fast addition). Infrared images of exothermic effects of the cryopreservation solutions were monitored relative to the rate of addition. Prefreeze and postthaw colony-forming unit assays, total nucleated cells, and CD34+ cell counts were compared. RESULTS: Maximum temperature excursions observed were less than 6°C, regardless of the rate of solution addition. Fast addition resulted in peak excursions approximately twice that of slow addition but the magnitude and duration were minimal and transient. Slow addition of CryoStor CS10 (i.e., final concentration ≤ 5% DMSO) resulted in significantly better postthaw CD34+ cell recoveries; no other metrics were significantly different. Fast addition of CryoStor resulted in similar postthaw metrics compared to slow addition of the in-house solution. CONCLUSION: Slow and fast addition of cryopreservation solutions result in mean temperature changes of approximately 3.3 to 4.45°C. Postthaw recoveries with CryoStor were equivalent to or slightly better than with the in-house cryopreservation solution. CryoStor also provides several advantages including reduced processing time, formulation consistency, and reduced DMSO in the frozen product (≤ 5%).

Improved post-thaw recovery of peripheral blood stem/progenitor cells using a novel intracellular-like cryopreservation solution.

BACKGROUND AIMS: Peripheral blood stem cells (PBSC) have become the preferred stem cell source for autologous hematopoietic transplantation. A critical aspect of this treatment modality is cryopreservation of the stem cell products, which permits temporal separation of the PBSC mobilization/collection phase from the subsequent high-dose therapy. While controlled rate-freezing and liquid nitrogen storage have become 'routine' practice in many cell-processing facilities, there is clearly room for improvement as current cryopreservation media formulations still result in significant loss and damage to the stem/progenitor cell populations essential for engraftment, and can also expose the patients to relatively undefined serum components and larger volumes of dimethylsulfoxide (DMSO) that can contribute to the morbidity and mortality of the transplant therapy. METHODS: This study compared cryopreservation of PBSC in a novel intracellular-like, fully defined, serum- and protein-free preservation solution, CryoStor (BioLife Solutions Inc.), with a standard formulation used by the Fred Hutchinson Cancer Research Center (FHCRC). Briefly, human PBSC apheresis specimens were collected and 5 x 10(7) cells/1 mL sample vial were prepared for cryopreservation in the following solutions: (a) FHCRC standard, Normosol-R, 5% human serum albumin (HAS) and 10% DMSO; and (b) CryoStor CS10 (final diluted concentration of 5% DMSO). A standard controlled-rate freezing program was employed, and frozen vials were stored in the vapor phase of a liquid nitrogen freezer for a minimum of 1 week. Vials were then thawed and evaluated for total nucleated cell count (TNC), viability, CD34 and granulocytes by flow cytometry, along with colony-forming activity in methylcellulose. RESULTS: The PBSC samples frozen in CryoStor CS10 yielded significantly improved post-thaw recoveries for total viable CD34(+), colony-forming units (CFU) and granulocytes. Specifically, relative to the FHCRC standard formulation, cryopreservation with CS10 resulted in an average 1.8-fold increased recovery of viable CD34(+) cells (P=0.005), a 1.5-fold increase in CFU-granulocyte-macrophage (GM) numbers (P=0.030) and a 2.3-fold increase in granulocyte recovery (P=0.045). CONCLUSIONS: This study indicates that use of CryoStor for cryopreservation can yield significantly improved recovery and in vitro functionality of stem/progenitor cells in PBSC products. In addition, it is important to note that these improved recoveries were obtained while not introducing any extra serum or serum-derived proteins, and reducing the final concentration/volume of DMSO by half. Further in vitro and in vivo studies are clearly necessary; however, these findings imply use of CryoStor for cryopreservation could result in improved engraftment for those patients with a lower content of CD34(+) cells in their PBSC collections, along with reducing the requirement for additional apheresis collections and decreasing the risk of adverse infusion reactions associated with higher exposure to DMSO.

Cell preservation in reparative and regenerative medicine: evolution of individualized solution composition.

The expanding complexity of biologics banked for therapeutic applications necessitates the development of improved preservation technologies for support of the emerging fields of reparative and regenerative medicine. Currently, a number of media or "solutions" are utilized for the preservation of biologics. Given the diversity of cell systems utilized in the regenerative medicine arena, we hypothesized that the development of unique (individualized) preservation solutions designed to meet the distinct molecular biological requirements of individual systems would provide for enhanced and extended preservation. To evaluate this hypothesis, coronary artery smooth muscle cells (CASMCs), coronary artery endothelial cells (CAECs), hepatic cells (C3A), and skeletal muscle cells (SKMCs) were hypothermically preserved for 2 to 7 days at 4 degrees C in either cell culture medium, University of Wisconsin Solution (UW or ViaSpan), or HypoThermosol (HTS) variants. Cells were then assayed for viability, using the alamarBlue assay as well as calcein-AM, subsequent to their return to normothermic (37 degrees C) temperatures for up to 5 days. CASMC viability was best maintained when preserved in HTS plus Trolox/EDTA, CAEC viability was highest when preserved in HTS plus Trolox, SKMCs stored in HTS plus Trolox/RGD demonstrated enhanced viability, and C3A cells were best preserved in HTS plus FK041. The data suggest that solution compositions that address the differences in cell death mechanisms limiting preservation efficacy can result in targeted improvement matched to specific cell types. These observations support the custom solution hypothesis of cell and tissue preservation.