Low-energy electron-beam treatment as alternative for on-site sterilization of highly functionalized medical products – A feasibility study

Gotzmann, Gaby; Portillo, Javier; Wronski, Sabine; Kohl, Yvonne; Gorjup, E.; Schuck, H.; Rögner, Frank-Holm; Müller, M.; Chaberny, Iris F.; Schönfelder, Jessy; Wetzel, C.

doi:10.1016/j.radphyschem.2018.04.008

Cited by 23 publications

(12 citation statements)

References 23 publications

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“…It therefore requires less radiation shielding (millimeters to centimeters, depending on the energy used) and can be used in normal laboratories. As low energy electrons only have a limited penetration depth, they have so far mainly been used for the sterilization of surfaces 20 – 22 . We have previously shown that LEEI can be used to inactivate pathogens in liquid solution, as long as the layer thickness is below 150 μm.…”

Section: Introductionmentioning

confidence: 99%

Automated application of low energy electron irradiation enables inactivation of pathogen- and cell-containing liquids in biomedical research and production facilities

Fertey

Thoma

Beckmann

et al. 2020

Sci Rep

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Ionizing radiation is widely used to inactivate pathogens. It mainly acts by destroying nucleic acids but causes less damage to structural components like proteins. It is therefore highly suited for the sterilization of biological samples or the generation of inactivated vaccines. However, inactivation of viruses or bacteria requires relatively high doses and substantial amounts of radiation energy. Consequently, irradiation is restricted to shielded facilities—protecting personnel and the environment. We have previously shown that low energy electron irradiation (LEEI) has the same capacity to inactivate pathogens in liquids as current irradiation methods, but generates much less secondary X-ray radiation, which enables the use in normal laboratories by self-shielded irradiation equipment. Here, we present concepts for automated LEEI of liquids, in disposable bags or as a continuous process. As the electrons have a limited penetration depth, the liquid is transformed into a thin film. High concentrations of viruses (Influenza, Zika virus and Respiratory Syncytial Virus), bacteria (E. coli, B. cereus) and eukaryotic cells (NK-92 cell line) are efficiently inactivated by LEEI in a throughput suitable for various applications such as sterilization, vaccine manufacturing or cell therapy. Our results validate the premise that for pathogen and cell inactivation in liquids, LEEI represents a suitable and versatile irradiation method for standard biological research and production laboratories.

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Section: Introductionmentioning

confidence: 99%

Automated application of low energy electron irradiation enables inactivation of pathogen- and cell-containing liquids in biomedical research and production facilities

Fertey

Thoma

Beckmann

et al. 2020

Sci Rep

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“…36 For B. pumilus spores, a D 10 value of 1.2 kGy was indicated by the manufacturer (MesaLabs) using a Cobald 60 source. Using LEEI, a D 10 value of 1.4 kGy was determined by Gotzmann et al 37 Thus, gamma irradiation and LEEI have comparable D 10 values. Considering the D 10 value, 8.4 kGy are theoretically required to eradicate six decimal powers of B. pumilus spores.…”

Section: Discussionmentioning

confidence: 88%

“…The D 10 value describes the dose necessary to reduce a viable population by one power of 10. 36 A D 10 value for LEEI of 1.4 kGy was determined for B. pumilus by Gotzmann et al 37 By division of the applied dose by the D 10 value, the log reduction was calculated. For a thickness of 285 μm, the calculated log reduction and the measured log reduction did not significantly differ (log reduction 0.1 ± 0.1, calculated log reduction 0.1, p = 0.59) (Table 3).…”

Section: Resultsmentioning

confidence: 99%

Stabilization and Sterilization of Pericardial Scaffolds by Ultraviolet and Low-Energy Electron Irradiation

Walker

Schönfelder

Tugtekin

et al. 2018

Tissue Engineering Part C: Methods

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Pericardial scaffolds have a wide spectrum of clinical applications ranging from patches for vascular reconstruction and abdominal wall defects to bioprosthetic heart valves. The current gold standard of tissue preparation involves disinfection and cross-linking using glutaraldehyde. However, glutaraldehyde-associated toxicity as well as rapid calcification and premature graft failure represent the major modes of failure.1 Therefore, a variety of alternative strategies for tissue conservation have been pursued. However, none of those strategies has substituted glutaraldehyde as the method of choice yet. Furthermore, safe sterilization procedures that are nondetrimental to the tissue's functionality are scarce. We have developed a novel procedure to stabilize and sterilize (S) acellular pericardial scaffolds combining photo-initiated ultraviolet cross-linking (U) with low-energy electron irradiation (LEEI). This SULEEI procedure avoids the use of glutaraldehyde and utilizes LEEI as effective sterilization method. A bioburden of 5.1 × 105 ± 4.6 × 105 viable bacteria could be successfully inactivated by SULEEI treatment applying a surface dose of 30.6 ± 2.8 kGy. By challenging high-density polyethylene foil stacks with >106 Bacillus pumilus spores in different depths and modeling the dose distribution within the scaffolds, a maximum sample thickness of 175 μm was determined for successful sterilization. Moreover, SULEEI treatment appeared nondetrimental to the ultimate tensile strength (17.6 ± 8.6 MPa vs. 17.4 ± 9.6 MPa) of the scaffolds compared with glutaraldehyde-treated pericardia. Cell number and overall metabolic activity of human endothelial cells were significantly higher on SULEEI-treated pericardia compared with control samples. In contrast, no cell proliferation could be detected on glutaraldehyde-treated pericardia. Thus, the SULEEI procedure may be a promising novel procedure for glutaraldehyde-free tissue preparation for pericardium-based tissue transplants and tissue engineering.Impact StatementPericardium-based tissue transplantation is a lifesaving treatment. Commercial glutaraldehyde-treated pericardial tissue exhibits cytotoxicity, which is associated with the accelerated graft failure. Replacement of glutaraldehyde has been suggested to overcome those drawbacks. In this study, we report a toxin-free method that combines tissue stabilization with a terminal sterilization. Our data indicate that the SULEEI procedure, which is part of an issued patent, may be a promising first step toward glutaraldehyde-free pericardium-based tissue transplants. Thus, our results may contribute to improving cardiovascular treatment strategies.

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“…Since the penetration depth of the accelerated low energy electrons is limited to < 1 mm in water (19), a thin film of liquid has to be generated to ensure complete irradiation (18). Compared to gamma irradiation, LEEI allows delivery of a high dose rate, which leads to a shorter treatment time (18,20). One of the greatest benefits of LEEI is the generation of only small amounts of secondary radiation (the Bremsstrahlung, X-rays) (18).…”

Section: Introductionmentioning

confidence: 99%

Low Energy Electron Irradiation Is a Potent Alternative to Gamma Irradiation for the Inactivation of (CAR-)NK-92 Cells in ATMP Manufacturing

et al. 2021

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BackgroundWith increasing clinical use of NK-92 cells and their CAR-modified derivatives in cancer immunotherapy, there is a growing demand for efficient production processes of these “off-the-shelf” therapeutics. In order to ensure safety and prevent the occurrence of secondary tumors, (CAR-)NK-92 cell proliferation has to be inactivated before transfusion. This is commonly achieved by gamma irradiation. Recently, we showed proof of concept that low energy electron irradiation (LEEI) is a new method for NK-92 inactivation. LEEI has several advantages over gamma irradiation, including a faster reaction time, a more reproducible dose rate and much less requirements on radiation shielding. Here, LEEI was further evaluated as a promising alternative to gamma irradiation yielding cells with highly maintained cytotoxic effector function.MethodsEffectiveness and efficiency of LEEI and gamma irradiation were analyzed using NK-92 and CD123-directed CAR-NK-92 cells. LEE-irradiated cells were extensively characterized and compared to gamma-irradiated cells via flow cytometry, cytotoxicity assays, and comet assays, amongst others.ResultsOur results show that both irradiation methods caused a progressive decrease in cell viability and are, therefore, suitable for inhibition of cell proliferation. Notably, the NK-mediated specific lysis of tumor cells was maintained at stable levels for three days post-irradiation, with a trend towards higher activities after LEEI treatment as compared to gamma irradiation. Both gamma irradiation as well as LEEI led to substantial DNA damage and an accumulation of irradiated cells in the G2/M cell cycle phases. In addition, transcriptomic analysis of irradiated cells revealed approximately 12-fold more differentially expressed genes two hours after gamma irradiation, compared to LEEI. Analysis of surface molecules revealed an irradiation-induced decrease in surface expression of CD56, but no changes in the levels of the activating receptors NKp46, NKG2D, or NKp30.ConclusionsThe presented data show that LEEI inactivates (CAR-)NK-92 cells as efficiently as gamma irradiation, but with less impact on the overall gene expression. Due to logistic advantages, LEEI might provide a superior alternative for the manufacture of (CAR-)NK-92 cells for clinical application.

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Low-energy electron-beam treatment as alternative for on-site sterilization of highly functionalized medical products – A feasibility study

Cited by 23 publications

References 23 publications

Automated application of low energy electron irradiation enables inactivation of pathogen- and cell-containing liquids in biomedical research and production facilities

Automated application of low energy electron irradiation enables inactivation of pathogen- and cell-containing liquids in biomedical research and production facilities

Stabilization and Sterilization of Pericardial Scaffolds by Ultraviolet and Low-Energy Electron Irradiation

Low Energy Electron Irradiation Is a Potent Alternative to Gamma Irradiation for the Inactivation of (CAR-)NK-92 Cells in ATMP Manufacturing

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