Experience of contamination during autologous cell manufacturing in cell processing facility under the Japanese Medical Practitioners Act and the Medical Care Act

Operator stress factors and cell contamination risks in cell processing facilities: An online survey-based analysis

The field of regenerative medicine is rapidly evolving, with an increasing number of approved cell preparations. However, cell processing facilities (CPFs) still heavily rely on manual operations by cell processing operators (CPOs). The intricate nature of cell culture and stringent sterility requirements impose a considerable psychological burden on CPOs, particularly the risk of cell contamination. This study delves into the psychological aspects experienced by CPOs in relation to the risk of contamination during cell culture. An online survey was conducted across 47 sites to investigate concerns regarding contamination and the strategies implemented to mitigate contamination risk in cell processing facilities. The survey findings revealed that 72 % of operators expressed concern about contamination, with 18 % reporting direct experiences of contamination. This indicates that the perceived contamination risk in CPFs is higher than the actual reported incidents. Furthermore, this study examines operational practices, such as material handling, and the utilization of biological safety cabinets (BSCs). The results highlight variations in BSC utilization and material handling practices, underscoring potential operational challenges. Implementing risk assessments and leveraging evidence-based data at each site could help address these challenges and alleviate the psychological strain on CPOs. This, in turn, would enhance the quality of cell therapy products and improve the well-being of CPOs.

Changeover method for biosafety cabinets using ozone gas

This study evaluated the effectiveness of a biosafety cabinet equipped with an ozone generator, particularly during the transition periods between the production of cell products. As living cell products cannot undergo sterilization, maintaining an aseptic manufacturing environment is paramount. Raw materials, often derived from human tissues, are frequently contaminated with various resident bacteria, necessitating environmental resets after each process. The utility of this device against bacteria, including endotoxins, endospores, and fungi endemic to human tissues, could facilitate safe and reproducible production changeovers through a simplified, one-button operation. This study focused on bacteria resistant to conventional cleaning protocols, specifically targeting endospore-forming bacteria with robust resistance to disinfectants, spore-forming fungi, and included analyses of endotoxins. The effects of ozone exposure on Pseudomonas aeruginosa (an endotoxin-producing bacterium), Bacillus subtilis (an endospore-forming bacterium), and Aspergillus brasiliensis (a spore-forming fungus) were assessed. In the dedicated biosafety cabinet equipped with an ozone generator, the treatment group exposed to ozone showed a significant reduction in both colony-forming units and endotoxin levels in Pseudomonas aeruginosa at 1.0 × 104 colony-forming units (CFUs) compared to the control group. Moreover, the ozone treatment markedly decreased the colony formation of Bacillus subtilis endospores and Aspergillus brasiliensis spores. Given its effectiveness against endospores and endotoxins-among the most challenging bacterial derivatives to eliminate-the device demonstrates potential for enhanced bacterial control in Grade A biosafety cabinets within cell product manufacturing facilities. The system may substantially reduce operator stress by ensuring product safety through straightforward operational procedures and high reproducibility, although further validation is required.

Microbes identified from monitoring cell manipulations in 5-year life of the Cell Factory G. Gaslini

Introduction

Quality and safety of a cell product, essential to guarantee the health of patients, depends on many factors including an appropriate environmental monitoring of the manufacturing rooms. Nonetheless, the maintenance of a controlled environment is requested to minimize the risk of contamination. Thus, a timely detection of changes in microbiological trends is important to adopt promptly effective measures against resistant strains that, in turn, may invalidate not only the sanitization procedures but also the safety of the cell product.

Methods

We analyzed microbes found in our cell processing clean room over the last 5 years. We used 10.147 plates for air sampler, passive air monitoring and for checking instruments and operators of the production unit.

Results

From these plates, 747 colonies were subjected to identification by the MALDI-TOF Vitek® MS system and the large majority of them was gram positive (97.8%) as witnessed by the finding that the most represented genera harvested from the classified areas were Staphylococcus (65%), Micrococcus (13%), Kocuria (8%) and Bacillus (5%). We never detected fungi. Most microbes found in the operators (both from class A and B) were collected from forearms and resulted of the Staphylococcus genus.

Conclusions

The observed microbial contamination is to be attributed to the personnel and no substantial microbial pitfalls in our Cell Factory has been detected.

Operator-derived particles and falling bacteria in biosafety cabinets

Introduction

To ensure the sterility of cell products that cannot undergo conventional sterilization processes, it is imperative to establish and maintain a clean room environment, regulated through environmental monitoring, including particle counts. Nevertheless, the impact of particles generated by operators as potential contaminants remains uncertain. Thus, in this study, we conducted an accelerated test to assess the correlation between particles generated by operators and airborne bacteria, utilizing biosafety cabinets within a typical laboratory setting. These biosafety cabinets create a controlled environment with air conditioning and high-efficiency particulate air (HEPA) filters, offering fundamental data relevant to cell production.

Materials and methods

We conducted a simulation followed by real-time experiments involving human operations to explore the quantity of particles, particle sizes, and the percentage of bacteria within these particles. This investigation focused on conditions with heightened particle generation from operators within a biosafety cabinet. The experiment was conducted on operators wearing textile and non-woven dustless clothing within biosafety cabinets. It entailed tapping the upper arms for a duration of 2 min.

Results

Observations under biosafety cabinet-off conditions revealed the presence of various particles and falling bacteria in textile clothing. In contrast, no particles or falling bacteria were detected in operators wearing dustless clothing within biosafety cabinets. Notably, a correlation between 5 μm particles and colony-forming units in textile clothing was identified through this analysis. The ratio of falling bacteria to the total number of particles within the biosafety cabinet was 0.8 ± 0.5 % for textile clothing, while it was significantly lower at 0.04 ± 0.2 % for dustless clothing.

Conclusion

This study demonstrated that the number of particles and falling bacteria varied depending on the type of clothing and that quantitative data could be used to identify risks and provide basic data for operator education and evidence-based control methods in aseptic manufacturing areas. Although, this study aims to serve as an accelerated test operating under worst-case conditions, the results need to make sure the study range in general research.

Assessment of microbial contamination in laser materials processing laboratories used for prototyping of biomedical devices

Microbial contamination of medical devices during pilot production can be a significant barrier as the laboratory environment is a source of contamination. There is limited information on microbial contaminants in laser laboratories and environments involved in the pilot production of medical devices. This study aimed to determine the bioburden and microbial contaminants present in three laser laboratories - an ISO class 7 clean room, a pilot line facility and a standard laser laboratory. Microbiological air sampling was by passive air sampling using settle plates and the identity of isolates was confirmed by DNA sequencing. Particulate matter was analysed using a portable optical particle counter. Twenty bacterial and 16 fungal genera were isolated, with the genera Staphylococcus and Micrococcus being predominant. Most isolates are associated with skin, mouth, or upper respiratory tract. There was no significant correlation between microbial count and PM2.5 concentration in the three laboratories. There were low levels but diverse microbial population in the laser-processing environments. Pathogenic bacteria such as Acinetobacter baumannii and Candida parapsilosis were isolated in those environments. These results provide data that will be useful for developing a contamination control plan for controlling microbial contamination and facilitating advanced manufacturing of laser-based pilot production of medical devices.

Volatile organic compounds and ionic substances contamination in cell processing facilities during rest period; a preliminary assessment of exposure to cell processing operators

Introduction

Cell processing operators (CPOs) use a variety of disinfectants that vaporize in the workspace environment. These disinfectants can induce allergic reactions in CPOs, due to their long working hours at cell processing facilities (CPFs). Ionic substances such as CH₃COO^- generated from peracetic acid, nitrogen oxides (NOx) and sulfur oxides (SOx) from outdoor environment are also known to pollute air. Therefore, our objective was to assess the air quality in CPFs and detect volatile organic compounds (VOCs) from disinfectants and building materials, and airborne ionic substances from outdoor air.

Methods

Sampling was conducted at three CPFs: two located in medical institutions and one located at a different institution. Air samples were collected using a flow pump. Ion chromatographic analysis of the anionic and cationic compounds was performed. For VOC analysis, a thermal desorption analyzer coupled with capillary gas chromatograph and flame ionization detector was used.

Results

Analysis of the ionic substances showed that Cl^-, NOx, and SOx, which were detected in large amounts in the outdoor air, were relatively less in the CPFs. Ethanol was detected as the main component in the VOC analysis. Toluene was detected at all sampling points. As compared to the other environments, air in the incubator contained larger amounts of VOCs, that included siloxane, tetradecane, and aromatics.

Conclusions

No VOCs or ionic substances of immediate concern to the health of the CPOs were detected during the non-operating period. However, new clinical trials of cell products are currently underway in Japan, and a variety of new cell products are expected to be approved. With an increase in cell processing, health risks to CPOs that have not been considered previously, may become apparent. We should continue to prepare for the future expansion of the industry using a scientific approach to collect various pieces of information and make it publicly available to build a database.

Effect of disinfectants and manual wiping for processing the cell product changeover in a biosafety cabinet

Introduction

The process of cell product changeover poses a high risk of cross-contamination. Hence, it is essential to minimize cross-contamination while processing cell products. Following its use, the surface of a biosafety cabinet is commonly disinfected by ethanol spray and manual wiping methods. However, the effectiveness of this protocol and the optimal disinfectant have not yet been evaluated. Here, we assessed the effect of various disinfectants and manual wiping methods on bacterial removal during cell processing.

Methods

The hard surface carrier test was performed to evaluate the disinfectant efficacy of benzalkonium chloride with a corrosion inhibitor (BKC + I), ethanol (ETH), peracetic acid (PAA), and wiping against Bacillus subtilis endospores. Distilled water (DW) was used as the control. A pressure sensor was employed to investigate the differences in loading under dry and wet conditions. The pre-spray for wiping was monitored by eight operators using a paper that turns black when wet. Chemical properties, including residual floating proteins, and mechanical properties, such as viscosity and coefficient of friction, were examined.

Results

In total, 2.02 ± 0.21-Log and 3.00 ± 0.46-Log reductions from 6-Log CFU of B. subtilis endospores were observed for BKC + I and PAA, respectively, following treatment for 5 min. Meanwhile, wiping resulted in a 0.70 ± 0.12-Log reduction under dry conditions. Under wet conditions, DW and BKC + I showed 3.20 ± 0.17-Log and 3.92 ± 0.46-Log reductions, whereas ETH caused a 1.59 ± 0.26-Log reduction. Analysis of the pressure sensor suggested that the force was not transmitted under dry conditions. Evaluation of the amount of spray by eight operators showed differences and bias in the spraying area. While ETH had the lowest ratio in the protein floating and collection assays, it exhibited the highest viscosity. BKC + I had the highest friction coefficient under 4.0-6.3 mm/s; however, that of BKC + I decreased and became similar to the friction coefficient of ETH under 39.8-63.1 mm/s.

Conclusions

DW and BKC + I are effective for inducing a 3-Log reduction in bacterial abundance. Moreover, the combination of optimal wet conditions and disinfectants is essential for effective wiping in specific environments containing high-protein human sera and tissues. Given that some raw materials processed in cell products contain high protein levels, our findings suggest that a complete changeover of biosafety cabinets is necessary in terms of both cleaning and disinfection.

Cross-contamination risk and decontamination during changeover after cell-product processing

Introduction

During changeover in cell-product processing, it is essential to minimize cross-contamination risks. These risks differ depending on the patient from whom the cells were derived. Human error during manual cell-product processing increases the contamination risk in biosafety cabinets. Here, we evaluate the risk of cross-contamination during manual cell-processing to develop an evidence-based changeover method for biosafety cabinets.

Methods

Contaminant coverage was analyzed during simulated medium preparation, cell seeding, and waste liquid decanting by seven operators, classified by skill. Environmental bacteria were surveyed at four participating facilities. Finally, we assessed the effect of conventional UV irradiation in biosafety cabinets on bacteria and fungi that pose a cross-contamination risk.

Results

Under simulated conditions, scattered contamination occurred via droplets falling onto the surface from heights of 30 cm, and from bubbles rupturing at this height. Visible traces of contaminants were distributed up to 50 cm from the point of droplet impact, or from the location of the pipette tip when the bubble ruptured. In several facilities, we detected Bacillus subtilis, of which the associated endospores are highly resistant to disinfection. Irradiation at 50 mJ/cm² effectively eliminated Bacillus subtilis vegetative cells and Aspergillus brasiliensis, which is highly resistant to UV. Bacillus subtilis endospores were eliminated at 100 mJ/cm².

Conclusions

Under these simulated optimal conditions, UV irradiation successfully prevents cross-contamination. Therefore, following cell-product processing, monitoring the UV dose in the biosafety cabinet during cell changeover represents a promising method for reducing cross-contamination.

The environmental risk assessment of cell-processing facilities for cell therapy in a Japanese academic institution

Cell therapy is a promising treatment. One of the key aspects of cell processing products is ensuring sterility of cell-processing facilities (CPFs). The objective of this study was to assess the environmental risk factors inside and outside CPFs. We monitored the temperature, humidity, particle number, colony number of microorganisms, bacteria, fungi, and harmful insects in and around our CPF monthly over one year. The temperature in the CPF was constant but the humidity fluctuated depending on the humidity outside. The particle number correlated with the number of entries to the room. Except for winter, colonies of microorganisms and harmful insects were detected depending on the cleanliness of the room. Seven bacterial and two fungal species were identified by PCR analyses. Psocoptera and Acari each accounted for 41% of the total trapped insects. These results provide useful data for taking the appropriate steps to keep entire CPFs clean.

Viability evaluation of layered cell sheets after ultraviolet light irradiation of 222 nm

Introduction

The objective of this study was to evaluate the cell viability of layered cell sheets, irradiated with 222 nm UV light.

Methods

UV transmittance of 222 nm and 254 nm was evaluated when the cell sheets of NCTC Clone 929 cells were irradiated UV light. Cell viability was evaluated after irradiation of 222 nm using 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. Following irradiation of two layered cell sheets at 500 mJ/cm², the cell damage of lower layers was evaluated by a colony formation and MTT assays.

Results

The UV transmittance of 222 nm was 10 times less than that of 254 nm. A MTT assay revealed that cells of cell sheets irradiated at 222 nm was less damaged than those at 254 nm, when irradiated at 5 mJ/cm². Cell colonies were formed for cells of lower layers irradiated at 222 nm whereas no colony formation was observed for those irradiated at 254 nm. Significantly higher MTT activity was observed for cells of lower layers irradiated at 222 nm than at 254 nm.

Conclusions

It is concluded that 222 nm irradiation is biologically safe for cell viability.

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The cell viability of two-layered cell sheets was evaluated after irradiation of UV light at 222 nm.

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UV light at 222 nm is safer to the lower layer than the conventional UV light at 254 nm.

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The reason can be attributed to the lower transmission of UV light at 222 nm through cell sheets.

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UV light at 222 nm could be one of promising tools to be required for the sterilization in the field of regenerative therapy.

Variation in the manufacturing reproducibility of autologous cell-based products depending on raw material shipment conditions

To prepare an autologous cell-based product in a cell processing facility, the raw material, which is collected from a patient, must first be shipped from a medical institution to the facility. The quality of this raw material varies depending on the patient, and variations due to transport methods also occur. Because the quality must be uniform and manufacturing processes need to be adjusted to account for these variations, determining the effect of shipment conditions on raw materials is very important for estimating cell manufacturability in the process design. In this study, a group of medical institutions located in different areas requested similar cell-based products processed by the same manufacturing method to a company that is licensed under the Act on the Safety of Regenerative Medicine in Japan. Manufacturing reproducibility was analyzed based on 456 cell batches received from two clinics that were processed used the same manufacturing method. The specific growth rates that were observed in the early growth phase supposed that the proliferative potential of the primary cells in the raw material was influenced by transit time. Simultaneously, the variation of the specific growth rates in the late phase were supposed to be hardly occurred. Thus, this study evaluated shipping conditions of the raw materials for an autologous cell-based product, and a strategy for verifying the influence of transportation on quality in manufacturing was suggested.

Understanding the formation and behaviors of droplets toward consideration of changeover during cell manufacturing

Preventing the contamination of processed cells is required for achieving reproducible manufacturing. A droplet is one of the potential causes contamination in cell manufacturing. The present study elucidates the formation mechanism and characteristics of droplets based on the observation and detection of droplets on the base surface of the biological safety cabinet (BSC) where cell processing is conducted under unidirectional airflow. Pouring fluorescent solution into the vessel using a measuring pipette was conducted to visualize the formation of droplets by videos as well as visual detection by blacklight irradiation on the base surface of the BSC. The experiments revealed that airborne and non-airborne droplets emerged from bursting bubbles, which formed when the entire solution was pushed out of the measuring pipette. Therefore, the improving procedure of pouring technique when entire solution was not pushed out of the pipette realized no formation of the droplets due to the prevention of emergence of bubble. In addition, an alternative procedure in which the entire solution was poured into the deep point of the test tube prevented the flying of non-airborne droplets outside the tube, while airborne droplets that escaped the tube rode the airflow of BSC. These results suggested a method for the prevention of the droplet formation, as well as the deposit control of droplets onto the surface in BSC, leading to cleanup area in the BSC for changeover with environment continuity.

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The droplets were formed by bursting bubbles while pouring the solution.

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Improved procedure for the prevention of emergence of droplets was proposed.

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Classification of droplets proposes the procedure for cleanup the BSC.

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Changeover was categorized based on the status for environment continuity.

Quantitative analysis of operators' flow line in the cell culture for controlled manual operation

Introduction

Although cell culture has been widely used in the life sciences, there are still many aspects of this technique that are unclear. In this study, we have focused on the manual operations in the cell culture process and try to analyze the operators’ flow line.

Methods

During a course of approximately 6 years, we obtained the operators’ flow line data from two places (three layouts) and 38 operators (93 subcultures) using two network cameras and a motion detection software (Vitracom SiteView).

Results

Our investigation succeeded in quantifying the flow line of the subculture process and analyzed the time taken to carry out the process, to travel around the workplace. For the subculture process, the total time of the process being rerated the time of the operation in the place where the main operation is performed; the total distance of travel and the counts of travel not being related to the total time of the process. Based on these results, we propose a new way of evaluating the efficiency of cell culture process in terms of time and traveling. We believe that the results of this study can guide cell culture operators in handling cells more efficiently in cell manufacturing processes.

Conclusions

The flow line analysis method suggested by us can record the operators involved and improve the efficiency and consistency of the process; it can, therefore, be introduced in cell manufacturing processes. In addition, this method only requires network cameras and motion detection software, which are inexpensive and can be set up easily.

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The subculture process was quantified successfully irrespective of location.

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The time of some operation correlated with the total time of subculture process.

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The distance and the counts of travel did not correlate with total time of subculture process.

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Establishment of a new method of evaluation of operation efficiency, based on time and travel.

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The results of flow line analysis can be used effectively to guide operators.