US 20050048642 A1
A multi-slide assembly includes various components that alone or in combination facilitate testing of test samples with minimal manipulation of assay components. Moreover, the various device components permit centrifugation, culturing and analysis of each test sample to be performed in the same assembly. A frame retains a plurality of reaction vessel assemblies between a pair of opposing channels that are configured to slidably receive the opposing ends of each reaction vessel assembly. A strip cap seals the openings in each reaction vessel using cap members having sealing rings circumscribing the external walls thereof to form compression seals with internal walls of the reaction vessels. Furthermore, in a method of making a multi-well slide assembly, an ultrasonic welding process removably bonds a plurality of wells to a slide plate to provide an adequate seal therebetween during centrifugation, yet still enable separation thereof by an operator.
1. A method of making a reaction vessel of the type including at least one well defined by a sidewall member removably coupled to a slide plate, the method comprising:
(a) forming a bond between the sidewall member and the slide plate via ultrasonic welding, the bond sufficient to withstand centrifugation forces; and
(b) controllably weakening the bond between the sidewall member and the slide plate via ultrasonic welding to permit selective separation of the sidewall member from the slide plate.
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This application is a divisional application of U.S. Ser. No. 10/139,550, filed on May 6, 2002 by Bunn et al. (issued as U.S. Pat. No. 6,803,239), which is a divisional application of U.S. Ser. No. 09/510,717, filed on Feb. 22, 2000 by Bunn et al. (issued as U.S. Pat. No. 6,383,820), which is a divisional application of U.S. Ser. No. 08/958,521 filed on Oct. 27, 1997 by Bunn et al., (issued as U.S. Pat. No. 6,096,562) all entitled “MULTI-SLIDE ASSEMBLY INCLUDING SLIDE, FRAME AND STRIP CAP, AND METHODS THEREOF,” which applications are incorporated by reference herein.
The invention is generally directed to cell culturing, immunological and molecular tools for use in biomedical research and diagnostics applications. More specifically, the invention is directed to cell culture, immunological and molecular tools such as slides, wells, vessels and the like for use in research or diagnostic testing of biological test samples.
Cell culture vessels such as flasks, dishes, slides, wells, culture tubes and the like are utilized in a number of biomedical diagnostics applications to test for the presence of microorganisms in test samples such as patient specimens from humans or other animals. Likewise, other types of reaction vessels similar in format but differing in surface characteristics to cell culture vessels are utilized for immunological, molecular and biochemical analysis of the same.
For example, microorganisms may be tested for to assist in the diagnosis of an infection. Some infectious diseases are distinctive enough to be identified clinically. Most pathogens, however, can cause a wide spectrum of clinical symptoms in humans, many of which are not unique to a particular pathogen. Therefore, it is often necessary to use microbiologic laboratory methods to identify the specific organism that is causing a disease.
One method used to detect the presence of a microorganism causing an infection is to isolate and culture in an artificial medium the microorganism causing the infection. Both the presence and number of microorganisms in a patient's specimen can assist in defining the cause of a disease. To use this process, a specimen from a patient is placed in a liquid, solid or semi-solid medium that permits the growth of selective microorganisms. The medium may also include inhibitory substances that prevent the growth of microorganisms in the medium, other than the microorganisms the maker of the medium has selected. If the microorganism is present in the patient's specimen, it will grow in the medium and its growth will be detected.
Another method that may be used to identify the presence of a microorganism is to expose a living cell line that is known to be susceptible to particular microorganisms to a test sample from a patient. If the microorganism is present in the patient's specimen, the cells may exhibit cytopathic effects induced by that microorganism, which may be detected and confirmed by a fluorescent labeled monoclonal antibody. Typically, with such a process a cell line is grown on a suitable surface such as a cover slip disposed in the Petri dish, dram vial, culture tube or other vessel. Alternatively, the cell culture may be grown directly on the surface of a suitable vessel. The cell culture is inoculated with a clinical test sample, and then some of these vessels may be centrifuged to quickly introduce the microorganism into the cells. Typically, the cell culture is then incubated for a period of time to grow the organism, whereby the presence or non-presence of the microorganism is later analyzed, typically through visual inspection using an optical reader such as a microscope.
In many cases, to grow or culture cells both a solid surface and a liquid medium are needed. The solid surface provides a location upon which the cells can adhere, and the solid support typically mimics the cell's natural environment in the tissue from which they were derived. Often, the flat surfaces of tissue-culture flasks, trays, Petri dishes, multi-well culture plates, and even the inside surfaces of large roller bottles make ideal support surfaces for growing cells.
The medium in which the cells are immersed is the cells' source of nutrients. It is an artificial environment similar enough to the cells' natural environment to permit their continued growth and proliferation. The basic formulas of culture media typically consist of water, salts and amino acids, to which supplements such as serum, antibiotics, or growth factors can be added.
Most cell culture vessels are typically not well suited for performing all tasks in a diagnostic process. For example, a culture tube or Petri dish is often suitable for inoculation and/or incubation; however, many such cell culture vessels are not well suited for centrifugation and/or analysis. In general, cell growth occurs best on a modified plastic surface, while analysis and other processing is best performed on a glass surface. Consequently, test samples often must be transported between various vessels during the diagnostic process. Moreover, with vessels such as dram vials, culture tubes or Petri dishes, each test sample must be handled individually, which can become cumbersome when working with numerous samples.
Multi-well culture plates may also be used in diagnostic testing. A multi-well plate has multiple wells formed into a two-dimensional array within which one or more cell lines are grown. Often, however, such multi-well plates are restrictive in that it is difficult to culture multiple cell lines in a single plate due to different culture times required for each type of cell line. Moreover, there is a possibility of cross-contamination between wells. Also, if one cell culture in a multi-well plate becomes contaminated or otherwise inoperative, typically the entire plate must be discarded.
It has also been found that centrifugation causes a number of concerns with many conventional cell culture vessels. Typically, such vessels must be relatively sturdy to withstand the forces that occur in centrifugation. Moreover, an adequate seal must be maintained during centrifugation to prevent loss of the cell culture and/or contamination of other cultures, or the laboratory environment.
Accordingly, it is desirable to maintain a tight seal with various cell culture vessels subjected to centrifugation. However, a tight seal on a vessel may induce an aerosol effect when the sealing member for the vessel is removed. It should be appreciated that whenever a sealing member is removed under a tight seal, a vacuum is temporarily induced in the vessel. When the vacuum is released after the sealing member is fully removed, viruses or other biological agents or contaminants may be released into the atmosphere due to the sudden pressure change in the vessel. Such agents may be dangerous to operators, and they may also cause contamination of nearby samples.
Another concern is the vaporization of certain harmful processing chemicals such methanol, ethanol, isopropanol, dimethyl suphoxide (DMSO), phenol, or chloroform. Consequently, great care must be taken in removing a sealing member from conventional cell culture vessels.
Another conventional cell culture vessel is a multi-well slide assembly such as the SonicSeal four well slide available from Nalge Nunc International, which includes multiple wells joined together and secured to a slide plate through a breakable ultrasonic weld. An opener may be used to remove the upper structure of the wells from the slide plate such that the cell cultures disposed on the slide plate may be analyzed. However, such assemblies are not designed for centrifugation and include no suitable manner of sealing each well during centrifugation. The loose-fitting lid provided with such assemblies is insufficient to tightly seal each well.
Such assemblies are typically welded together using a two-step ultrasonic welding process. The upper structure is provided with a thin flange with a triangular cross-section on a mating end thereof (commonly referred to as an energy director) that is melted during ultrasonic welding to weld the upper structure to the slide plate. In the first step, the upper structure is ultrasonically welded to a distance of approximately one half of the length of the energy director to energize the molecules therein. Then, in the second step, a stronger weld is formed between the upper structure and slide plate through limited additional ultrasonic welding that further energizes the molecules but does not cause the energy director to become completely fused—thereby providing the break-apart property of the slide. After bonding, about 88 percent of the energy director is used up, with the mating surface between the upper structure and slide being only about 0.015 inches wide, which is only about 88 percent of the width of the base of the energy director, and only about 34 percent of the thickness of the sidewalls of the upper structure. The resulting bond is air- and liquid-proof and has sufficiently high mechanical strength for culturing purposes. However, the bond tends to leak during and/or after exposure to centrifugation forces, and thus is not suited for use in a centrifuge.
Therefore, a significant need exists for improved tools and an enhanced manner of performing cell culturing, diagnosis and/or testing of biological test samples with greater efficiency, reliability and accuracy. Specifically, a need exists for tools that are particularly suited for multiple activities to minimize the effort, time and potential contamination concerns associated with transferring test samples, cell cultures and the like between vessels.
The invention addresses these and other problems associated with the prior art in providing a multi-slide assembly including various components that alone or in combination facilitate testing of biological, chemical or molecular test samples with minimal manipulation of assay components. Specifically, various operations such as centrifugation, inoculation, culturing and/or analysis of a test sample may be performed in the same reaction vessel to speed up testing and/or to minimize cross-contamination between multiple samples. Batch processing of numerous test samples may therefore be performed expediently and reliably.
Consistent with one aspect of the invention, a method is provided for testing a test sample in which a reaction vessel defined at least partially by a sidewall member removably coupled to a slide plate is inoculated with a test sample and centrifuged. In addition, the sidewall member is separated from the slide plate to permit analysis of the test sample on the slide plate.
Consistent with another aspect of the invention, a frame is used to retain a plurality of reaction vessels, with each reaction vessel including opposing ends. The frame includes a pair of opposing channels including first and second ends and configured to slidably receive the opposing ends of each reaction vessel, and first and second retaining mechanisms respectively disposed proximate the first and second ends of the pair of opposing channels and configured to retain each reaction vessel within the pair of opposing channels.
Consistent with yet another aspect of the invention, a method is provided for performing a common operation on a plurality of test samples, each test sample being housed in one of a plurality of reaction vessels, each vessel of the type including opposing ends. The method includes placing the plurality of reaction vessels in a frame including a pair of opposing channels including first and second ends and slidably receiving the opposing ends of each reaction vessel, and first and second retaining mechanisms respectively disposed proximate the first and second ends of the pair of opposing channels and retaining each vessel within the pair of opposing channels. The method also includes performing the common operation on the plurality of test samples while the plurality of reaction vessels are retained in the frame.
Consistent with another aspect of the invention, a strip cap is also provided for use in sealing an opening in the reaction vessel having an internal wall defining the same. The strip cap includes a cap member having an external wall, a mating portion of which is configured to abut the internal wall of the vessel around a perimeter of the opening, and a sealing ring circumscribing the external wall of the cap member and configured to form a compression seal with the internal wall of the vessel.
Consistent with a further aspect of the invention, a multi-well slide is provided including a slide plate, a plurality of wells coupled to the slide plate, each including an internal wall defining an opening to the well, and a strip cap. The strip cap includes a strip member, a plurality of cap members coupled to the strip member, each cap member having an external wall, a mating portion of which is configured to abut the internal wall of one of the plurality of wells around the perimeter of the opening thereto, and a plurality of sealing rings, each sealing ring circumscribing the external wall of one of the plurality of cap members, and each sealing ring configured to form a compression seal with the internal wall of one of the plurality of wells.
Consistent with yet another aspect of the invention, a method of making a reaction vessel of the type including at least one well defined by a sidewall member removably coupled to a slide plate is provided, including forming a bond that is sufficient to withstand centrifugation forces between the sidewall member and the slide plate via ultrasonic welding; and controllably weakening the bond between the sidewall member and the slide plate via ultrasonic welding to permit selective separation of the sidewall member from the slide plate.
Consistent with a further aspect of the invention, a reaction vessel is provided, including a slide plate removably secured to a sidewall member through an ultrasonically-welded and controllably-weakened bond. The sidewall member includes an energy director disposed at an end thereof, the energy director having a base with a width that is substantially equal to that of the sidewall member proximate the end thereof. The bond includes a fused junction between the slide plate and the sidewall member that is formed of substantially the entire energy director and that defines a mating surface that is substantially equal to the width of the base of the energy director.
These and other advantages and features, which characterize the invention, are set forth in the claims annexed hereto and forming a further part hereof. However, for a better understanding of the invention, and of the advantages and objectives attained through its use, reference should be made to the Drawing, and to the accompanying descriptive matter, in which there is described exemplary embodiments of the invention.
Turning to the Drawing, wherein like numbers denote like parts throughout the several views,
The plurality of multi-well slide assemblies 20 are housed in a frame 100 that is suitable for performing batch operations on the cell cultures within the multi-well slide assemblies. Also shown is a pry-bar opener 200 that may be used to separate the upper structures of the multi-well slides from the slide plates thereof.
The discussion hereinafter will focus on cell culture applications of the invention. However, it should be appreciated that the invention may be utilized in other applications, e.g., in immunological and molecular applications, cell-based assay applications, etc. Consequently, while various components of the embodiments described hereinafter, such as vessels, assemblies, surfaces, and the like, may be described with reference to cell culturing applications, one skilled in the art will appreciate that the principles of the invention may be applied to other applications of reaction vessels and reaction vessel assemblies in general without departing from the spirit and scope of the invention.
Each multi-well slide 30 shown in
An upper structure 40 including a plurality of wells 42 is ultrasonically welded to slide plate 32. Each well 42 forms a cell culture chamber with slide plate 32, and each includes an inner wall 42 a and a top edge 42 b defining an opening 42 c in each well. The plurality of wells 42 are integrally molded to one another and supported by flange 44. Upper structure 40 forms a sidewall member that defines each well in conjunction with slide plate 32. It should be appreciated that other sidewall member designs, e.g., defining any number of wells, may be used in the alternative. For example, a sidewall member may only define one well.
The design of multi-well slide 30 is similar in some respects to the No. 138121 SonicSeal slides available from Nalge Nunc International. The slide plate has standard dimensions of a microscope slide. Moreover, either or both of the slide plate and the upper structure may be formed of Permanox® plastic or other similar materials that have suitable chemical resistance for performing culturing, analysis and other processing, as well as biological compatibility for facilitating cell growth thereon. The upper structure 40 is ultrasonically welded to the slide plate 32 to form a liquid tight seal. Moreover, the upper structure 40 is removable by prying the upper structure from the slide plate 32 with a pry-bar opener 200 that breaks the ultrasonic weld.
The aforementioned SonicSeal slides have been found to not be particularly well-suited to centrifugation due to the lack of strength in the ultrasonic welds used thereon. To address this concern, it is desirable to provide a coupling between the upper structure 40 and slide plate 32 that is suitable of withstanding centrifugation, but which still enables the removal of the upper structure by a user.
Ultrasonic welding in general is known in the art. See, e.g., U.S. Pat. No. 4,715,911, which is incorporated by reference herein. Consistent with the invention, it is desirable to utilize a two-step, weld-by-distance ultrasonic welding process that creates an initial bond in a first welding step that is sufficiently leak-proof during and after centrifugation. Then, in a second welding step, the upper structure and slide plate are further compressed to cause a secondary melt that controllably weakens the bond without compromising the leak-proof seal established by the first step.
For example, as shown in
For the first weld cycle, a pressure of about 15 to about 30 psi, more preferably about 20 psi may be used, with a weld distance of about 0.014 to about 0.019 inches (0.36 to 0.48 mm), more preferably about 0.017 inches (0.42 mm), and a weld duration of about 0.5 to 1.0 seconds, more preferably about 0.8 seconds. The first weld cycle fully bonds the upper structure to the slide plate as a result of the energy director becoming fully molten during welding.
For the second weld cycle, a pressure of about 20 to about 40 psi, more preferably about 30 psi may be used, with a weld distance of about 0.001 to about 0.005 inches (0.03 to 0.13 mm), more preferably about 0.004 inches (0.09 mm), and a weld duration of about 0.5 to 1.0 seconds, more preferably about 0.8 seconds. A dwell time of about 3 to about 10 seconds may be used, more preferably about 5.0 seconds, to permit some cooling of the components while under pressure and thereby minimize failures. Additional suitable weld parameters include a stroke position of about 0.1 inches (2.54 mm), a mechanical stop of about 4.3 inches (109.22 mm), an end weld of about 6.0 inches (152.4 mm), a pre-trigger of about 5.5, a moderate down speed, and a trigger of about 2.0. It should be appreciated that the parameters may vary depending upon the particular ultrasonic welding machine used.
It has been found that, by generating a full weld to approximately the full length of the energy director in a first welding step, a bond is generated between the upper structure and slide plate that can withstand centrifugation forces (e.g. at least 700 G's for an hour) and still be leak-proof during and after centrifugation. Then, by welding in the second weld at least the remaining length of the energy director at a greater pressure (typically about 10 psi greater) than in the first weld, a controlled weakening of the bond may be generated to reduce the breakage resistance of the bond to a level that permits separation of the upper structure from the slide plate, but that is still capable of withstanding centrifugation. In addition, the width of the bond is permitted to occupy, in the minimum, the full width of the energy director, and in the maximum, the full thickness of the sidewall, which is believed to contribute to the improved robustness of the bond compared to conventional designs. In the embodiment discussed above, the total weld distance can be about 0.02 inches (0.51 mm) for a energy director with a length of about 0.019 inches (0.49 mm), and the width of the bond therefore can range from about 0.017 inches (0.42 mm) wide to about 0.043 inches (1.09 mm). Therefore, as shown in
In addition, it has been found to be beneficial to cool molded components prior to ultrasonic welding. For example, the components may be allowed to air cool for 12-24 hours before welding. Alternatively, a similar degree of cooling may be performed for two or three minutes on an air conditioned cooling conveyor that transports components from the molding process to the welding process.
Conventional welding processes that attempt to first energize the components, and second weld the components together have been found to not provide the same combination of resistance to centrifugation forces and separability with controllable results. For example, a conventional welding process may utilize a two-step process, with a first step utilizing an air pressure of 10 psi, a distance of 0.010 inches, and a weld time of 1.2 seconds, and a second step utilizing an air pressure of 15 psi, a distance of 0.007 inches, and a weld time of 0.5 seconds. Other weld parameters of the conventional process utilize a dwell time of 5.0 seconds, a mechanical stop of 0.420 inches, and end weld of 6.110 inches, a pretrigger of 5.726 inches a trigger of 1.6 and a moderate down speed. Even by increasing welding pressure, time and/or distance to theoretically increase the bond strength, it has been found that conventional processes of this type do not provide suitably consistent results. In particular, it is believed that the width of the bond, which is only a portion of the width of the energy director, and less of a portion of the width of the sidewall, does not provide suitable robustness for centrifugation applications.
In other conventional welding processes, the full length of an energy director may be used up during welding, resulting in a bond that occupies the full width of the sidewalls. However, the bonds resulting from these conventional processes are permanent and are not breakable by an operator without damage to the welded components. Consequently, these processes are not suitable for many of the applications disclosed herein that utilize the separability of a slide plate and an upper structure to perform analysis of test samples.
It should be appreciated that the above-described welding parameters may be varied in different applications. It should be appreciated that materials other than Permanox® plastic may require different welding characteristics. For example, for polystyrene, it may be desirable to utilize a longer energy director (e.g., about 0.025 to about 0.035 inches, or 0.64 to 0.89 mm), with a correspondingly greater weld distance in the first weld step (e.g., about 0.022 to about 0.031 inches, or 0.56 to 0.79 mm).
It should also be appreciated, however, that the design of multi-well slide 30 is but merely one type of cell culture vessel suitable for use with the various components of the invention. For example, various enclosed cell culture vessels including flasks, dishes, culture tubes and structures including a plurality of wells in various geometric shapes, etc. may be used. Moreover, various non-enclosed cell culture vessels such as slides, wafers, discs, plates, microarrayed surfaces, etc. may also be used, as may other types of reaction vessels suitable for other immunological and molecular applications, for example. Accordingly, the invention should not be limited to the particular design of multi-well slide 30, nor specifically to the material and/or the manner of coupling the upper structure to the slide plate, disclosed herein.
Strip cap 50 of multi-well slide assembly 20 is shown in greater detail in
As best shown in
Bottom portion 64 of each cap member may be flat or domed. A flat profile provides a lower profile for the cap member, while a domed member may be useful in smaller designs to reinforce the cap member. An annular bevel at 64 a is defined between mating portion 63 and bottom portion 64 to further facilitate insertion of each cap member into its associated well.
Moreover, it has been found that the use of multiple seals can provide a venting effect when the cap member is removed, which minimizes the vacuum created in the chamber, and consequently minimizes aerosol effects associated therewith.
For example, as shown in
Strip member 52 (best shown in
A pair of tabs 54 also extend from the ends of strip member 52. Each includes fingernail ridges 54 a that assist in the manual removal of the strip cap. Moreover, one of the tabs 54 may also include an orientation marking 54 b extending transverse to ridges 54 a so that strip member 52 may be secured to a multi-well slide in a repeatable, predetermined orientation. Consequently, the risk of cross-contamination due to placing strip member 52 on backwards relative to a previous installation of the same is reduced.
The design of strip member 52 also permits tweezers to be utilized to remove the strip cap by grasping flange 53. Moreover, if strip cap 50 is constructed of a soft material, a knife or scalpel may be used to separate the individual cap members such that each is separately removable with tweezers. This enables wells to be opened and closed individually. For example, this may enable a sealed control sample to be maintained while various testing operations are performed on the test samples. It also enables various samples to be inoculated at different starting times to account for the different growth rates of various cell lines.
Typically, strip cap 50 is integrally injection molded with a flexible material such as a USP Class 6 or compatible medical-rated plastic that is not toxic to test samples or other biological agents that may come in contact with the strip cap during testing. For example, one suitable material is low-density polyethylene, although other materials, such as high density polyethylene or polypropylene, among others, may also be used.
The design of strip cap 50 provides significant advantages over conventional designs. For example, strip cap 50 provides a strong seal that is suitable for centrifugation as well as transportation of multi-well slide assemblies. The seal provided by such a strip cap enables cell cultures of living cell lines to be commercially prepared in wells, sealed within the assemblies along with a suitable transport medium, and then sold, stored and/or transported to customer laboratories for later use. Customers are then able to merely remove the strip caps and inoculate the cell lines as desired to perform testing, without first having to culture their own cell lines.
Another significant advantage is that the strip caps are replaceable such that after inoculation, the multi-well slide assemblies may be resealed and utilized during centrifugation. This seal may assist in maintaining the media's pH during shipment as well as during the diagnostic process.
Frame 100 is typically sized at about 5.025″ by 3.365″ to provide a footprint that is substantially similar to a conventional microwell plate or multi-well cell culture dishes (e.g., 6, 12, 24, 48, 96, 384, etc. well plates). Moreover, the height of frame 100 is slightly smaller than that of a microwell plate. The dimensions enable frame 100 to be used with the various processing and analysis equipment that currently exist for processing microwell plates or multi-well cell culture dishes. For example, various liquid handling systems such as washers, dispensers, robotic fingers, pipettors, and other ancillary equipment such as centrifuges having centrifuge buckets/carriers have been developed to utilize assemblies having such footprint. Moreover, various optical viewers, including microscopes (specifically, the stages thereof), spectrophotometers, luminometers, fluorimeters, and colorimetric readers, among others, may also be compatible with such a footprint. Other robotics, manufacturing systems and coating systems, may also recognize such footprint.
Frame 100 is typically constructed of an autoclavable, chemically resistant, strong, and freezable material such as Noryl plastic available from General Electric, which is a 20% glass-filled modified polyphenylene oxide. Other materials, including various plastics and metals, whether transparent or opaque, may also be used consistent with the invention. The frame may or may not be reusable.
As shown in
Retaining mechanism 130 includes a stop member 132 and retaining mechanism 150 includes a stop member 152, each of which close off an end of both opposing channels. Moreover, retaining mechanism 130 includes a detent 134 that extends from stop member 132 towards the opposite end of the channel. The detent 134 is spaced from lower wall 114 approximately the same distance as the upper wall retaining portion 112 a—approximately the width of the structure that is retained within the channels. Detent 134 is beveled along an upper surface thereof to facilitate movement of retained objects over the detent. Retaining mechanism 150 may also include an upper surface 154 (See
It should be appreciated that various other retaining mechanisms may also be used to close the ends of the opposing channels and thereby secure reaction vessel assemblies within the frame. For example, either or both of the retaining mechanisms may be removable to selectively open or close the end of the opposing channels. The removal or retaining mechanisms may be secured by any number of means, including clips, screws, detents, tabs, etc. In general, any structure that abuts retained objects to prevent movement thereof beyond the ends of the channels may be used. Moreover, the retaining mechanisms may abut such objects either within the channels or in the space defined therebetween. However, it is believed that the illustrated structure provides advantages over various alternatives as no moving parts are required, and as the configuration thereof is relatively simple and reliable for manufacturing and use.
Frame 100 is configured to hold four multi-well slides such as multi-well slide assemblies 20 of
Next, as illustrated in
Next, as illustrated in
The gap remaining within each channel once all assemblies 20 a-20 d are inserted therein may be slightly larger than the width of detent 134 to permit each assembly to be removed easily when slid rearward, yet retained securely when the assemblies are slid forward. In the alternative, the gap may be made slightly less than the width of the detent, such that some resistance must be overcome to dislodge an assembly when all are retained within the frame.
As shown in
Access aperture 162 enable viewing of cell cultures from the top or bottom of the assembly, e.g. by using an optical viewer such as a microscope. Moreover, by configuring access apertures 162 as voids, an optical viewer may be oriented directly proximate the slide plates of assemblies 20 a-20 d if necessary.
In the alternative, access apertures may be omitted from frame 100, e.g., by providing a planar opaque lower support member. Such a design may be useful, for example, to provide high contrast with the cell cultures for use with other types of optical viewers.
An additional function of member 160 is to provide support for assemblies 20 a-20 d, particularly during centrifugation. When utilizing multi-well slide assemblies 30 having removable upper structures, bowing might otherwise break the well seals and cause leakage and contamination of the cell cultures during this process. The design of lower support member 160 therefore supports assemblies 30 to prevent any such bowing.
Moreover, the indicia on each cap member may also coordinate with matching indicia 334 a-334 d molded or printed onto surface 332 of frame 330 to provide a visual cue that facilitates proper installation of each multi-well slide assembly 310 a-310 d into frame 330. Frame 330 may also have additional indicia, e.g., a manufacturer's logo 336, as well as transverse indicia 338 a-338 d located on surface 337. Indicia 338 a-338 d typically includes a series of letters or numbers (e.g., numbers 1-4 as shown in
Multi-slide assembly 10 and its various components have numerous uses in the biomedical diagnostics applications. For example, as described in greater detail below, one principle use for multi-slide assemblies consistent with the invention is in diagnosing the presence of a virus in a test sample such as a patient specimen. However, it should be appreciated that this usage is but one of numerous other applications where it is desirable to perform life science cell and tissue culturing, such as in research and diagnostic screening, viral screening, cancer screening, drug screening, etc. Therefore, the invention should not be limited to the particular application described herein.
For viral diagnostic screening, a live cell line is grown in each multi-well slide assembly. The cell lines selected typically have a particular sensitivity to a given virus for which is desired to determine the presence/non-presence thereof in a test sample. The virus uses the cell to replicate itself resulting in cytopathic effect (CPE) or an antigen that can be detected using a monoclonal antibody.
For example, for the influenza and parainfluenza viruses, the chosen cell line may be RHMK (Rhesus Monkey Kidney) cells. For CMV (cytomegalovirus), the chosen cell line may be MRC-5 (Human Lung). For VZV (Varicella-Zoster Virus), the cell line may be A549. For adenovirus, the cell line may be A549, or alternatively, HEp-2 (Human Larynx). For other viruses such as enterovirus, RSV (Respiratory Syncytial Virus), HSV (Herpes Simplex Virus), and others, the cell line may be any of the RHMK, MRC-5, A549, or HEp-2. Live cell lines or cultures, which are sensitive to other viruses, may also be used in the alternative.
Cells may be grown in each multi-well slide assembly in a clinical laboratory in a manner known in the art. In the alternative, the assemblies may be prepared by a manufacturer of such assemblies using commercially-grown cells.
In either case, the empty wells within each assembly are inoculated with cells and the cells are cultured in a growth medium such as Dulbecco's Modified Eagle's Medium (DMEM). When the cells are grown in the clinical laboratory in which the diagnostic testing is to be performed, the growth medium may be removed such that test samples may be used to inoculate the cell culture. If, however, the assemblies are prepared by a manufacturer, the growth medium may be removed and replaced with a transport medium that keeps the cells stable during transport. The multi-well slide assemblies are then sealed with strip caps, packaged and transported to customers. Moreover, such assemblies may be mounted in groups of four within frames for packaging and transport.
It should be appreciated that, given the flexibility provided by the multi-well slide assemblies as well as the use of multiple assemblies in a frame, any number of combinations of cell types may be provided in each multi-slide assembly. Typically, each well in a multi-well slide assembly has the same cell type, since otherwise different culturing times for different cell types may make it more difficult to ensure adequate growth of cell cultures within a given assembly.
Once cell cultures are formed in the multi-well slide assemblies, selected assemblies are inoculated with test samples such as patients' specimens. Multi-well slide assemblies may be inoculated individually, or alternatively, can be placed in a frame with any desired combination of cell cultures represented in the different assemblies.
If the multi-well assemblies are pre-manufactured assemblies supplied with commercially-grown cell cultures, the strip caps are first removed. Next, the transport medium may be aspirated from the wells, and the wells are optionally rinsed, e.g., with a rinse agent such as Hanks Balanced Salt Solution (HBSS). In addition, a small amount (e.g. about 0.02 ml) of growth/maintenance medium such as EMEM (Eagle's Minimum Essential Medium) or serum free medium, is optionally added to maintain the cell cultures during inoculation and to buffer test sample toxicity. Typically, the amount of growth/maintenance medium is small so that any viruses in the test sample are maintained in close proximity to the cell culture.
Next, predetermined amounts of test samples are introduced into the wells to inoculate the cell cultures. Then, the strip caps are reinstalled on each of the assemblies in preparation for centrifugation.
If the multi-well slide assemblies are not yet disposed in a frame, they may be so mounted such that the frame may be placed in a suitable microwell plate carrier bucket of a centrifuge. Centrifugation is then performed on all the assemblies concurrently, e.g. at 700 G's for about one hour. Centrifugation assists in introducing any viruses into a cell culture more rapidly to speed up the diagnostic process.
Next, once the cell cultures have been centrifuged, the strip caps are removed from the assemblies and a growth medium is optionally added. The assemblies are then covered with lids and are incubated at an elevated temperature for a predetermined time (e.g., 36° Celsius for multiple days in a CO2 incubator). The lids are utilized in lieu of the strip caps in this process to permit some degree of CO2 transfer during incubation. In some applications, strip caps may instead be utilized to seal the wells from air. During incubation, it may also be desirable to periodically replace the growth medium as necessary.
Upon completion of incubation, the test samples may be analyzed for potential cytopathic effects or antigen expression. Typically, the lids or strip caps are removed and any growth media is aspirated from the cell cultures. The cell cultures may be fixed, stained, etc., as necessary to permit suitable analysis of the cell cultures. For example, the cells may be fixed with acetone, dried and then stained with a drop of appropriate monoclonal conjugate. The slide containing the cells is incubated, rinsed with PBS and observed under a microscope.
Next, it may be desirable to remove the upper structure of the multi-slide assemblies from the slide plate, typically by inserting a suitable opener to pry the upper structure from the plate. For example, one suitable pry-bar opener is illustrated at 200 at
By virtue of its angled orientation, the opener is able to fit between the various assemblies in the frame to perform the separation. Moreover, when the upper structure of an adjacent assembly in the frame has already been removed, the angled orientation of the opener prevents damage or contamination to the cells on the adjacent slide plate when removing the upper structure of an assembly.
Alternatively, the cells may be fixed and processed once the upper structures have been removed from the slide plates from each assembly. Finally, cover slips may then be applied over the fixed and processed cells, whereby the cells are then ready for visual microscopic analysis.
Cell cultures may be analyzed by various optical viewing devices including microscopes, spectrophotometers, luminometers, etc. Moreover, by virtue of the open access to both surfaces of the slide plates through frame 100, analysis may be performed from either side of the slide plates. Moreover, the assemblies may be removed from the frame and separately analyzed if desired.
Therefore, it should be appreciated that the various embodiments of the invention provide significant advantages in simplifying and accelerating diagnostic testing. Moreover, it has been found that the various embodiments also provide improved performance over conventional cell culture vessels such as dram vials and culture tubes as they have been found to be more sensitive, often experiencing more pronounced cytopathic effects more quickly. Moreover, it has been found that cross-contamination is reduced compared to various multi-vessel assemblies such as multi-well plates. Another advantage is that the need for glass cover slips, as is often required for cell growth and testing with dram vials or Petri dishes, is eliminated. Moreover, the inherent hazards associated with the use of glass in a laboratory are avoided. Other advantages of the various embodiments of the invention will be apparent to one skilled in the art.
Various modifications may be made to the various embodiments without departing from the spirit and scope of the invention. Therefore, the invention lies in the claims hereinafter appended.