ABSTRACT

Flow cytometry is a powerful tool that finds applications in various fields such as immunology, molecular biology, cancer biology, virology, and infectious disease monitoring. A significant portion of the research in these disciplines is supported by flow cytometry shared resource laboratories (SRLs). There are several types of flow cytometers available for use in SRLs, including analyzers, sorters, imaging flow cytometers, and mass cytometers. Each type has different challenges when it comes to maintenance and life expectancy. An independent online survey was conducted to better understand instrument maintenance and turnover in flow cytometry SRLs. Questions regarding instrument uptime (availability), its usage, routine maintenance, and cost associated with it were addressed. The respondents also answered questions pertaining to the frequency of deep cleaning of the instrument and quality control. In addition, the survey queried about the source of funding used to purchase the instruments and possible reasons for a replacement. Presented herein are the results compiled from 146 core facilities that provide a look at the operation within a typical SRL, with the responses reflecting researchers’ experiences with handling flow cytometers.

Conflict of Interest: The authors declare no conflicts of interest.

ADDRESS CORRESPONDENCE TO: Ron Orlando, Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602 (Phone: 706-542-4429; Fax: 706-542-4412; Email: [email protected])

INTRODUCTION

No matter which technology or equipment a shared resource laboratory (SRL) specializes in, they all share common concerns regarding instrument maintenance and life expectancy. SRL managers and directors contemplate the optimal strategies for maintaining an instrument, determining the right time to replace an instrument, and obtaining the necessary funding for service contracts or for acquiring new instruments. To gain deeper insights into how SRLs address these challenges, we opted to conduct a survey specifically among SRLs that are focused on flow cytometry. We believe that the responses gathered in this survey from flow cytometry SRLs can be extrapolated to SRLs focused on other technologies and instrumentation.

Flow cytometry technology has been around since the 1950s. Over the years, the instrumentation, the cell types analyzed, and the assays performed have become more diverse and complex.[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15] What started out as a way to count cells has developed into a technology in which tens of thousands of cells are analyzed per second for expression of multiple proteins, viability, and function. Today, fluorescent antibody panels containing 15 or more antibodies are routinely used to identify unique cell populations with very distinct properties and functions.

Flow cytometers can be divided into 2 broad categories based on their function: analyzers and sorters.[16],[17] As their name implies, analyzers assess the cells in the sample, and the assayed cells are not recovered. Sorters make up the second category of flow cytometers. Sorters possess comparable capabilities to analyzers along with being able to separate cells into different purified populations based on their fluorescent signature. These purified populations can then be used for downstream applications such as single-cell RNA sequencing and western blots. These purified cell populations are often reintroduced into culture for expansion or functional studies.

An alternative method of categorizing flow cytometers is based on how the signal is detected. Employing this way to categorize flow cytometers results in 4 different types of flow cytometers: traditional flow cytometers, mass cytometers,[18],[19],[20] imaging flow cytometers,[21],[22],[23] and full spectrum flow cytometers.[24],[25] When most individuals think of flow cytometers, they think of the traditional flow cytometers. These types of instruments use both diodes and photomultiplier tubes[26] to detect the fluorescent signal, with a single fluorescent molecule being detected at each detector. Longpass and bandpass filters are placed in front of the detectors to narrow the wavelength detected. Mass cytometers have been around since the early 2000s and combine a flow cytometer with a mass spectrometer.[18],[19],[20] Unlike the other 3 types of flow cytometers, cells intended for analysis using a mass cytometer are labeled with antibodies conjugated to isotopes of rare earth metals. As with a traditional flow cytometer, when assaying cells on a mass cytometer, the labeled cells are brought to the detection device within a fluidic stream. The distinction lies in the fact that the cells upon reaching the detection device are atomized and sent through a mass spectrometer. Time of flight is utilized to identify the rare earth metal isotope(s) bound to the cell. Imaging flow cytometers combine flow cytometry with microscopy. These instruments use fluorescent-labeled antibodies and images of each cell, and bright field and fluorescence are taken as the cells go through the detection region. The newest type of flow cytometer is the full spectrum flow cytometer,[24],[25] which use a series of avalanche photodiodes as detectors. The detectors are set up for each laser starting at 15 to 30 nm from the laser wavelength and at 15 to 30 nm intervals until 815 nm. These systems provide a comprehensive value across the entire range, yielding the dye spectrum or a fingerprint. The majority of fluorescent dyes possess unique spectra that allows one to distinguish them from each other.

Even though today’s flow cytometers have better sensitivity, can detect more markers, and collect data more rapidly than those of 25 years ago, the old instruments generate good and reliable data. Since the 1980s, flow cytometry data generated on any instrument produced by any company uses a standard data format that is open source and readable in third party software. In many cases, researchers do not need the latest and advanced flow cytometer to answer their research questions. Flow cytometers entail a considerable financial investment, with costs ranging from $50 000 to $750 000 or beyond, based upon the desired features and specifications. Thus, figuring out when and how to replace an older instrument is a major issue for most flow cytometry SRLs/core facility directors.[27],[28],[29] The majority of institutions lack the available funds to acquire the most current and advanced flow cytometers. For this reason, most if not all flow cytometry SRLs expend substantial efforts to prolong the operational lifespan of their existing instrumentation.

Information sought and aim of study

The survey whose results are presented below was designed to better understand instrument maintenance and turnover in flow cytometry SRLs. It assessed the age of the instruments in the facilities, whether instruments were maintained using service contracts, and who operates the instruments, that is, users or staff. The survey also examined why new instruments were purchased and which funding sources were utilized for the procurement of these new instruments. We anticipate that the outcomes presented and discussed in this study will serve as a valuable point of reference for SRLs in their capital purchase discussions as well as in devising strategic plans related to laboratory operations.

METHODS

An independent online survey was developed by the authors and shared using internet survey provider SurveyMonkey . The survey was made available on June 6, 2020, and was open for a total of 3 weeks. The goal of the survey was to obtain comprehensive information about flow cytometer facilities including the type of staffing, funding, instrument usage, frequency of routine maintenance, and the average annual maintenance cost associated with operating a laboratory among various other factors. The survey consisted of 4 multi-part questions, including a mix of open-ended and multiple-choice options. Respondents’ answers were kept anonymous. The original survey can be found in the supporting information (Supplemental Table 1). To gain a better understanding of the types of instruments used, the survey was divided into 3 categories: newest, oldest, and most-used instruments. If the instrument fell into 2 categories, the responses were collected based on the length of time the instrument was most occupied. Keywords that were commonly used in this study are defined in Supplemental Table 2. All monetary data has been converted to US currency to facilitate comparisons between countries.

Data were collated and analyzed using Microsoft Excel. Statistical significance of differences between means was determined by performing t-test for unpaired data.

RESULTS AND DISCUSSION

Demographic of respondents

The survey achieved participation from 146 respondents residing in 14 countries across 4 continents (Fig. 1A and Supplemental Data). The majority of survey participants were core facility directors (39.7%) or managers (34.3%, Fig. 1B) who worked at universities (64.6%), hospitals (8.9%), private institutions (6.3%), and companies (6.3%, Fig. 1C). At the time of the survey, 27.8% of the survey respondents identified themselves as members of the Association of Biomolecular Resource Facilities (ABRF), whereas the majority of participants (72.2%) were not (data not shown). The number of respondents and their demographics aligned with what would be expected based on the known distribution of flow cytometry SRLs across the world.

Figure 1
(A) Demographic information of the respondents that spanned across 4 continents (from 77 responses). (B) Job title of the respondents (146 responses). (C) The type of institution (from 79 responses) that respondents were associated with. Most respondents were core directors and managers from universities and hospitals, among others. (D) The types of instruments that were taken into consideration such as analyzers, sorters, imaging flow cytometers, and mass cytometers. (E) The year of purchase of different instruments. (F) Institution staffing such as PhD scientists, technicians, and others.
A	B
C	D
E	F

Instrumentation

The 2 most common types of flow cytometers in SRLs were analyzers (54.4%) and sorters (37.9%, Fig. 1D). Fewer SRLs have imaging flow cytometers (5.2%) and mass cytometers (2.5%, Fig. 1D). Fig. 1E illustrates the age distribution of these instruments in the period of 1980 to 2020. The results were grouped for the 1980-to-1990-year range, owing to fewer instruments purchased prior to 1990 and still in use. Subsequent responses for later years were grouped in 5-year periods. The respondents reported that the average age of the analyzers was 9 years old and spanned from 1980 to 2020. Sorters that became commercially available after 1990 had an average age of 8.5 years. Imaging and mass flow cytometers became available in 2005 and 2009, respectively. The “newness” of these types of instruments is reflected in the average age of the instruments in SRLs: 5 years for imaging flow cytometers and 1.5 years for mass cytometers.

Who operates the instruments?

As far as staffing was considered, 49.9% of laboratory staff in flow cytometry SRLs were technicians (bachelor’s or master’s level), 30.1% were PhD scientists, and 20.0% had other levels of education (Figure 1F). It was inferred from the data that the average laboratory staffing was 2 PhD scientists, 3 technicians, and 1 to 2 other staff members.

The majority of analyzers were operated by both users and SRL staff (58.1%; Fig. 2A). A smaller percentage was operated by only user (37.7%) or only staff (4.2%; Fig. 2A). This was not true for sorters, where 47.4% of sorters were operated by both user and staff, 44.9% were operated by only staff, and 7.7% of these were operated by only users (Fig. 2A). Imaging flow cytometers were predominantly operated by both user and staff (62.5%), while 25.0% of these were operated by only users and 12.5% operated by only staff (Fig. 2A). All of the 4 mass cytometers were staff operated exclusively, probably due to the mass spectrometer aspect of the instrument (Fig. 2A). What these results clearly demonstrate is that the more complex the instrumentation, the more likely it will be operated by a trained SRL staff.

Figure 2
(A) Type of operation for analyzers (167 responses), sorters (78 responses), imaging flow cytometers (8 responses), and mass cytometers (4 responses). A majority of analyzers, sorters, and imaging flow cytometers were operated by both user and staff, whereas all 4 mass cytometers were operated by staff members. (B) Instrument usage of newest, oldest, and most-used analyzers. (C) The type of operation versus year of purchase of analyzers. Newer analyzers were majorly being operated by both user and SRL staff. (D) Instrument usage of newest, oldest, and most-used sorters. (E) Type of operation such as user, staff, or both user and staff operated versus year of purchase of sorters. Older sorters were predominantly staff operated, whereas the newer ones were operated by both users and staff.
A	B
C	D
E

To understand how instrument age and usage level affects personnel decisions, the respondents were asked specific questions related to their oldest, newest, and most-used instruments in their SRL. Respondents indicated that a majority of newer analyzers were operated by both user and staff (62.9%), while older analyzers were just as likely to be user operated (46.9%) as both user and staff operated (46.9%; Fig. 2B). The most-used analyzers in the facility were predominantly operated by both user and staff (64.3%; Fig. 2B). It is evident from Fig. 2C that the newer analyzers were majorly being operated by both user and SRL staff.

When it came to newer sorters in the SRLs (Fig. 2D), they were primarily operated by both user and staff (65.4%), while a majority of older sorters were operated by staff only (52.8%). This difference most likely results from manufacturers in the past few years producing sorters designed to require less adjustments and operator intervention. Of course, these types of sorters are not intended for overly complex sorts. Interestingly, the most-used sorters were observed to be staff operated (56.2%), which may indicate that users prefer experienced SRL staff when it comes to sorting their samples even though this is associated with a higher cost. The distribution of user type versus the year of purchase for sorters is depicted in Fig. 2E, which shows that the older sorters were predominantly staff operated, whereas the newer ones were operated by both users and staff.

Maintenance

The average annual maintenance costs for analyzers (from 138 responses), sorters (69 responses), imaging flow cytometers (5 responses), and mass cytometers (3 responses) were $14,318, $25,328, $10,272, and $72,500, respectively (Supplemental Table 5). When the annual maintenance costs were analyzed with respect to the year of purchase of instruments (Fig. 3), it was evident that the newer analyzers and sorters (discerned from 10 newest instruments) had higher maintenance costs compared to older instruments (discerned from 10 oldest instruments). The average maintenance cost for the 10 newest and 10 oldest analyzers were $12,791.50 and $5168.20, respectively. The average maintenance cost for the 10 newest and 10 oldest sorters were $26,141.90 and $16,637.80, respectively (Supplemental Table 6). One plausible reason for this observation is that the cost of a service contract is tied to the price of instruments, and thus, more expensive, newer instruments by default may have a higher annual service contract. Another possibility is that the newer instruments can perform more complex tasks, resulting in higher repair costs.

Figure 3
Maintenance cost versus year of purchase of (A) analyzers and (B) sorters. All monetary data has been converted to US currency to facilitate comparisons between countries. Overall, the newest analyzers and sorters costed more in maintenance as compared to the oldest analyzers and sorters.
A	B

The cost of maintenance in user- and staff-operated instruments were not observed to be significantly different (P > 0.05) in the case of both analyzers and sorters. The average maintenance cost for user-, staff-, and both user- and staff-operated analyzers were seen to be $13,651, $14,860, and $15,742, respectively. The maintenance costs were $22,917, $22,772, and $21,780 for user-, staff-, and both user- and staff-operated sorters, respectively (Supplemental Table 7).

Analyzers with the highest usage in the SRLs were purchased between years 2004 and 2019 (average age = 6.5 years), while the most-used sorters were purchased between 2003 and 2015 (average age = 10 years). The survey also indicated that 68.3% of newest analyzers, 41.1% of most used, and 25% of older analyzers were under warranty/service contract. For sorters, 65.4% of newer instruments, 46.7% of most used, and 22.2% older instruments were under warranty/service contract (Supplemental Table 8). A lower percentage of older analyzers and sorters being under contract could potentially be attributed to manufacturers no longer offering service contracts for those models.

A majority of respondents mentioned their analyzers were repaired/maintained by the original equipment manufacturer (OEM; 62.9%) followed by in-house (institutional) staff (28.7%) and a third-party service provider (8.3%). The same trend held true for sorters, with 68.5% laboratories reporting the OEM, 22.2% of them stating in-house staff, and the remaining 9.3% respondents mentioning a third-party service provider (Supplemental Table 9). Interestingly, more in-house maintenance was observed for older analyzers and sorters, whereas more OEM maintenance was incorporated for newer analyzers and sorters (Fig. 4). It is reasonable to infer that older analyzers and sorters were likely maintained by in-house staff, as manufacturers no longer offered service contracts for them.

Figure 4
Type of maintenance service such as OEM, in-house (institutional), and third-party service provider versus year of purchase of (A) analyzers and (B) sorters. In-house maintenance was primarily observed for older analyzers and sorters, whereas OEM maintenance was predominantly used for newer analyzers and sorters.
A	B

The annual maintenance cost for analyzers was $12,761 in facilities contracting with the OEM, $10,772 with a third-party service provider, and $3189 when performed by in-house staff. The average annual maintenance costs for sorters were $21,199 using the OEM, $24,200 with a third-party service provider, and $8289 when performed by in-house staff (Supplemental Table 10). It was surprising to observe that using a third-party service provider did not provide significant cost savings compared to receiving service from the OEM. A reason for the lower cost associated with in-house service could be that the salary of the person providing the service or labor charge is not being included in this cost, hence comparing the cost of in-house maintenance to that provided by an external vendor may not an even comparison. The survey also aimed to find out if the in-house maintenance results in a longer waiting time for the instrument to be repaired. It was inferred that the wait times for in house were not significantly longer than OEM or third-part maintenance, as the percentage of time an analyzer was waiting to be repaired was 4.7% for the OEM, 9.0% for a third-party, and only 4.2% for in-house maintenance. Similarly, the percentage of time a sorter was waiting to be repaired was 5.7% for the OEM, 4.2% for a third-party, and 5.5% for in-house maintenance. The P-values obtained from t-tests (P > 0.05) suggested that these differences in percent wait times were not statistically significant in the case of both analyzers and sorters (Supplemental Table 10).

The average annual cost of consumables for analyzers, sorters, imaging flow cytometers, and mass cytometers were observed to be $4101 (from 105 entries), $5555 (65 entries), $1069 (6 entries) and $23,333 (3 entries), respectively. The fact that mass cytometers incurred the highest consumable costs is not surprising, given that they are a combination of flow cytometry and mass spectrometer, which by itself has been known for its expensive operational costs.

The cost of consumables was also found to be higher for newer instruments (as per 10 newest instruments) compared to older instruments (as per 10 oldest instruments) in the case of both analyzers and sorters (Supplemental Table 11). The average cost of consumables for the 10 newest and 10 oldest analyzers were $3750 and $955.9, respectively. The average cost of consumables for the 10 newest and 10 oldest sorters were $5392.9 and $3930.2, respectively.

An aspect the survey investigated was how frequently the laboratories schedule routine maintenance (preventative maintenance/staff maintenance). Respondents were given the following choices: monthly, every couple of months, twice a year, and annually. Respondents indicated that, typically, a laboratory housing analyzers and/or sorters scheduled preventative maintenance twice a year (analyzers: 56.2%, sorters: 52.6%) as shown in Supplemental Table 13. This observation was fairly consistent for instruments regardless of when the instrument was purchased (Fig. 5).

Figure 5
Frequency of maintenance versus year of purchase of (A) analyzers and (B) sorters. Typically, a laboratory housing an analyzer and/or sorter scheduled preventative maintenance twice a year regardless of when the instrument was purchased.
A	B

Typically, flow cytometers undergo a brief daily cleaning at day's end or between users. In addition to this routine cleaning, manufacturers often advise a more thorough and extensive cleaning (referred to as deep cleaning) every month or 2. The survey queried about the deep cleaning of the instruments. Respondents indicated that a majority of facilities performed a deep cleaning of analyzers, sorters, and imaging flow cytometers (Fig. 6) on a monthly basis (analyzers: 48.8%, sorters: 44.7%, imaging flow cytometers: 71.4%). In addition, the quality control was primarily performed on a daily basis for analyzers (62.1%) and sorters (65.8%) as shown in Fig. 7.

Figure 6
Frequency of deep cleaning of (A) analyzers, (B) sorters, and (C) imaging flow cytometers. A majority of facilities performed a deep cleaning of their analyzers, sorters, and imaging flow cytometers on a monthly basis.
A	B
C

Figure 7
Frequency of performing quality control on (A) analyzers and (B) sorters. The quality control was primarily performed on a daily basis for analyzers and sorters.
A	B

Survey respondents were asked to provide information about common reasons to perform instrument maintenance (Fig. 8). The most common reasons for performing nonroutine/scheduled maintenance on analyzers were failure to pass quality control (24.6%) and to ensure an acceptable coefficient of variation (CV) value (24.1%) followed by clogging (14.9%), high background (11.4%), and low instrument sensitivity (10.6%). An acceptable CV value is very critical to ensure the reproducibility of flow cytometry results, particularly when the results are important for medical diagnosis. The common reasons for performing nonroutine/scheduled maintenance on sorters were similar to the reasons for analyzers, with the additional reason of contamination issues (15.4%). Maintaining cleanliness in a sorter is essential because often the cells returned to the researcher are cultured or injected into animals.

Figure 8
Reasons why SRLs typically perform maintenance on (A) analyzers and (B) sorters. The most common reasons for performing nonroutine/scheduled maintenance on analyzers and sorters were failure to pass quality control to ensure an acceptable CV value and due to clogging.
A	B

The survey was also designed to query about what the likely reasons for replacing an instrument were (Fig. 9). The following options were provided: instrument no longer serviced by company/keeps having issues/too few features/users’ needs have changed/not upgradeable/other. The most common reason that facilities considered for replacing an analyzer was because the manufacturer was no longer going to service the instrument (27.1%). Other common reasons included users’ needs had changed (19.6%), instrument kept having issues (18.2%), and that their instrument was not upgradeable (14.6%). A similar trend was observed in the case of sorters, with the most common reasons for instrument replacement being instrument no longer serviced by the company (31.5%), users’ needs had changed (21.3%), instrument kept having issues (21.3%), and instrument was not upgradeable (15.8%).

Figure 9
Common reasons for replacing (A) analyzers and (B) sorters in SRLs. The probable reasons for replacing an analyzer and sorter were because the instrument was no longer serviced by the manufacturer, because users’ needs had changed, and because the instrument consistently experienced issues.
A	B

Instrument usage

To get a better understanding of instrument uptime (available time) versus used time, the survey asked respondents what percent of time the instrument was out of service waiting to be repaired, percent of time the instrument was unavailable for use due to routine maintenance, and percent of time the instrument was actually used. The answers were based on the past year (2019).

The percent of instrument uptime for analyzers averaged to 91.4%, with the remaining 4.6% of the time being out of service waiting to be repaired and 4.1% of the time unavailable for use due to routine maintenance. While there was no significant variation in instrument uptime over the years, it was interesting to note that older instruments purchased between 1980 and 1995 demonstrated an average instrument uptime of around 90% (data not shown). The comparison between the operational time of user- and staff-operated instruments (Supplemental Table 16A) indicated that the percent uptime for user-operated analyzers was higher (92.5%) than for analyzers operated by both user and staff (87.9%). The statistical difference between the data was confirmed by performing an unpaired t-test (P = 0.0052). This may indicate the significance of regular maintenance as well as the potential influence of user training and the guidance provided to users regarding the operation of the instruments. The survey indicated that the percent of time the instruments were out of service as well as unavailable for use due to routine maintenance were 3.63 and 3.66%, respectively, for user-operated analyzers, whereas 5.4 and 3.4%, respectively, for staff-operated analyzers. Finally, analyzers operated by both user and staff were 4.7% of the time out of service and 5.14% of the time occupied to perform routine maintenance.

The average operable time for sorters was observed to be 89.5%, with the remaining 5% of the time being out of service waiting to be repaired and 5.7% of the time unavailable for use due to routine maintenance. Similar to the trend discerned in the case of analyzers, the uptime of newer sorters were comparable to the oldest sorters (purchased between 1995 and 2000) that provided around 88% instrument uptime (data not shown). The operational time for user-, staff-, and both user- and staff-operated instruments (Supplemental Table 16B) were comparable (91.7, 88, and 88.8%, respectively). The percent of time the user-operated sorters were out of service as well as unavailable for use due to routine maintenance were 3.3 and 5.0%, respectively. The percent of time unavailable for staff-operated sorters were 5.4 and 6.5%, respectively, and were 6.4 and 5.7%, respectively, for both user- and staff-operated instruments. The instruments’ availability, duration of being out of service, and duration of being occupied for routine maintenance were quite similar between analyzers and sorters.

Funding source

The last section of the survey dealt with the sources of funds used to purchase instruments in flow cytometry SRLs. Respondents indicated that the majority of facilities used in-house (institutional) funds (57.3%) followed by a government instrumentation grant (15.2%), a government research grant (12.8%), and a private foundation (6.7%), among others (7.9%), to purchase their analyzers (Fig. 10A). There was a similar distribution of funding sources for sorters (Fig. 10B), imaging flow cytometers (Fig. 10C), and mass cytometers (Fig. 10D). A total 55.3% of sorters were funded by in-house funds, 23.7% by a government instrumentation grant, 13.2% by a government research grant, 5.3% by a private foundation, and 2.6% from other funding sources. The SRLs using an imaging flow cytometer (7 responses) obtained their funding from in-house funds (42.9%) and a government instrumentation grant (42.9%) followed by a government research grant (14.3%). The 4 respondents with mass cytometers in their SRL indicated that in-house funds (50%) were most frequently used to purchase the instrument followed by a government instrumentation grant (25%) and other funding sources (25%).

Figure 10
Sources of funding for (A) analyzers, (B) sorters, (C) imaging flow cytometers, and (D) mass cytometers. The most common source of funding was observed to be in-house funds followed by a government instrumentation grant among other sources. Additionally, NIH instrumentation grant information for (E) analyzers and (F) sorters are shown. Most US survey participants who utilized government funds to buy analyzers and sorters obtained them through the NIH S10 shared instrumentation grant.
A	B
C	D
E	F

Respondents residing in the United States were queried if the instruments were specifically purchased using a National Institutes of Health (NIH) shared instrumentation grant (NIH S10 award) or an NIH high-end instrumentation grant. The majority of survey respondents who used the US government funds to acquire their instruments purchased their analyzers (94.3%) and sorters (80%) using an NIH S10 award (Fig. 10E and 10F). Overall, 27% of all flow cytometers in the US SRLs were funded by an NIH S10 award (25% of analyzers and 34% of sorters). In addition, 14.4% of all analyzers and 17.8% of all sorters used by respondents from across the world were funded by an NIH S10 award. The survey data suggested that the number of flow cytometers funded by an NIH S10 award seemed to have increased from 1996 to 2020 (Fig. 11), revealing the increasing reliance of core laboratories on an S10 award to purchase the instruments and the importance of an NIH S10 award in facilitating cutting-edge research in flow cytometry SRLs. Data has been reported from 1996 to 2020 due to fewer responses about instruments purchased prior to 1996 (Supplemental Table 18). The average annual NIH S10 budget that was allocated for the purchase of flow cytometers between 2014 and 2021 was $4,257,880 (determined from NIH Office of Research Infrastructure Programs data).[30] This represented 5% of the total annual budget allocated for various instrument types. Flow cytometers comprised 7% of all funded instruments. The annual budget and number of instruments funded by an NIH S10 award between 2014 and 2021 are listed in Supplemental Table 19. With continued budget allocation by NIH to purchase flow cytometers in the recent years and an overall increase in the number of flow cytometers being funded by an NIH S10 grant from 1996 to 2020, we believe that the S10 award will continue to support core SRLs in the future in procuring state-of-the-art flow cytometers and expanding flow cytometry core laboratories across the United States.

Figure 11



Percentage of flow cytometers in the US SRLs that were purchased using an NIH S10 award. Data has been shown for flow cytometers purchased between 1996 and 2020 as fewer responses were obtained for flow cytometers acquired prior to 1996. An overall increase in the number of flow cytometers funded by an NIH S10 award was observed from 1996 to 2020.

CONCLUSIONS

An independent online survey was created to acquire comprehensive information about SRLs that use flow cytometers (analyzers, sorters, imaging flow cytometers, and mass cytometers). The survey achieved participation from 14 countries across 4 continents, primarily from core facility directors and managers working in universities, private institutions, and companies. The majority of analyzers in SRLs were operated by both user and staff. Older analyzers were often user operated or both user and staff operated. Both user and staff operation were also common for sorters, but the most-used sorters were observed to be mainly staff operated, suggesting a preference for experienced SRL staff. Recent sorters were mainly operated by both users and staff (65.4%), with older sorters largely operated by staff (52.8%), likely due to the emergence of sorter designs that require less operator involvement in recent years. Similarly, imaging flow cytometers were primarily operated by both users and staff, while all mass cytometers were exclusively staff operated, likely due to the mass spectrometry aspect of the instrument.

Maintenance costs varied by instrument type, with an average annual cost of $14,922 for analyzers, $25,328 for sorters, $10,271 for imaging flow cytometers, and $72,500 for mass cytometers. Newer analyzers and sorters incurred higher maintenance expenses that may be attributed to service contract costs being tied to instrument prices, resulting in higher annual costs for newer and more expensive instruments. The survey indicated that a significant portion of the newest analyzers (68.3%) and sorters (65.4%) were under warranty or service contracts. A lower percentage of older analyzers and sorters being under contract could potentially be due to manufacturers discontinuing service contracts for older models. Most respondents depended on the OEM for maintenance. Older analyzers and sorters had more in-house (institutional) maintenance, while newer ones relied on the OEM. The study found that the cost to service analyzers and sorters through the OEM was not observed to be significantly higher than contracting with a third-party service provider. The survey also checked if affordable in-house maintenance caused longer instrument wait times. Results showed that in-house maintenance wait times were comparable to OEM or third-party maintenance. It was also found that, typically, a laboratory housing analyzers and/or sorters scheduled preventative maintenance twice a year regardless of the instrument’s purchase date. Most facilities conducted monthly deep cleaning and daily quality control for their analyzers, sorters, and imaging flow cytometers. Furthermore, survey respondents indicated that the common reasons for performing nonroutine maintenance on analyzers and sorters included addressing quality control failures and maintaining acceptable CV values, among others. The survey also revealed that the common reasons for instrument replacement included manufacturer’s discontinuing service, evolving user needs, persistent issues with the instrument, and lack of upgradeability. The average uptime was 91.4% for analyzers and 89.5% for sorters, with older instruments from 1980 to 2000 still being operable (analyzers: 90%, sorters: 88%). No noticeable differences in downtime were found between user- and staff-operated instruments. This suggested the significance of routine maintenance and the potential influence of user training and guidance in instrument usage.

The survey queried about funding sources for instrument purchase in flow cytometry SRLs. In-house funds were commonly used. Furthermore, it was observed that the analyzers and sorters used by respondents in the United States were predominantly supported by an NIH S10 award, suggesting that the NIH S10 grant program greatly contributed to advancing research in these laboratories. Because of a consistent budget allotment from the NIH for acquiring flow cytometers, along with a general rise in the number of flow cytometers funded through an NIH S10 award between 1996 and 2020, we believe that the S10 award will continue supporting core SRLs in the future. This support will enable the procurement of cutting-edge flow cytometers and further expansion of core laboratories across the United States. We anticipate that the outcomes presented in this study will serve as a valuable resource for establishing a core laboratory, along with aiding in the long-term planning and management of core laboratory operations.

ACKNOWLEDGMENTS

The authors gratefully acknowledge the Association of Biomolecular Resource Facilities and Ken Schoppmann for sharing the online survey on SurveyMonkey. We would also like to thank the scientific community for their contributions to the data collected for this manuscript.