Sample chamber volume reducer

An apparatus includes a chamber insert capable of being received by a sample chamber of a conditioning system. The received chamber insert reduces the volume of the sample chamber and defines a cavity that substantially surrounds a sample holder located in the sample chamber.

BACKGROUND

This description relates to a device that reduces the volume of a sample chamber and the amount of content needed to fill the volume.

With the expansion of tissue engineering, biomaterial research, and other areas of biotechnology, bioreactors have been developed for conditioning biologic specimens. By incorporating a sealable chamber into a bioreactor, fluids and other content can be introduced into the conditioning of specimens. As such, the conditioning may include placing biologic samples into a stationary or flowing fluid to simulate blood flow, synovial fluid flow or other fluid associated environment.

SUMMARY

In general, in one aspect, an apparatus includes a chamber insert capable of being received by a sample chamber of a conditioning system. The received chamber insert reduces the volume of the sample chamber and defines a cavity that substantially surrounds a sample holder located in the sample chamber.

Implementations may include one or more of the following features. The chamber insert may include two or more segments, which when combined, define the cavity. The chamber insert may include a feature for directing fluid flow such as a coating, a ridged surface, etc. For a feature such as a ridged surface, the ridges may be substantially parallel. The parallel ridges may also direct fluid to flow over a specimen in a spiral manner. The sample chamber may include a chamber window. The chamber insert may include one or more openings that substantially aligns with the chamber window. The chamber insert may includes one or more types of materials such as synthetic material, plastic material, materials to reduce adhesion of cellular material, materials to promote adhesion of cellular material, materials that are degradable, etc. The chamber insert may be produced to be disposable after one or more uses.

In general, in one aspect, a conditioning system includes a sample chamber capable of receiving a specimen, and, one or more ports capable of providing a fluid to the sample chamber. The conditioning system also includes a chamber insert capable of being received by the sample chamber. The received chamber insert reduces the volume of the sample chamber and defines a cavity that substantially surrounds a sample holder located in the sample chamber.

Implementations may include one or more of the following features. The chamber insert may include two or more segments, which when combined, define the cavity. The port may provide a fluid to an exterior surface or an interior surface of the specimen. The chamber insert may include a feature for directing fluid flow over the specimen. The feature may include a ridged surface that includes substantially parallel ridges. The sample chamber may include a chamber window and the chamber insert may include an opening that substantially aligns with the chamber window. The chamber insert includes one or more types of material such as a plastic material.

In general, in one aspect, an apparatus includes a chamber insert capable of being received by a sample chamber of a conditioning system. The chamber insert includes a section of the sample chamber. The received chamber insert reduces the volume of the sample chamber and defines a cavity that substantially surrounds a sample holder located in the sample chamber.

Implementations may include one or more of the following features. The chamber insert may include two (or more) segments, in which a first segment includes a first wall section of the sample chamber and a second segment includes a second wall section of the sample chamber. The first wall section and the second wall section may form the section of the sample chamber. The chamber insert may include one or more types of material such as a transparent material.

These and other aspects and features and various combinations of them may be expressed as methods, apparatus, systems, means for performing functions, and in other ways.

Other features and advantages will be apparent from the description a the claims.

DETAILED DESCRIPTION

Referring toFIG. 1, a sample chamber100allows various types of tissues and other types of biomaterials to be conditioned. For example, specimens of blood vessels, cardiac muscle, bone, cartilage, spinal discs, tendons, skin, ligaments, trachea, heart valves or other types of material (e.g., tissue substitutes such as synthetic biomaterials) may be inserted and conditioned in the sample chamber100. In general, for conditioning, a user-defined conditioning profile specifies a desired mechanical stimulation of a sample. The conditioning profile may specify a desired stress or strain state applied to the sample and may vary in time. If a cyclic conditioning protocol is desired, the conditioning profile may describe a desired stress or strain state over a user-specified cycle and the profile repeated for a user-specified number of cycles.

One or more contents such as fluids or other media may be introduced into the sample chamber100for simulating environmental conditions typically experienced by a sample. For example, a specimen inserted into the sample chamber100may be immersed in a fluid to simulate the blood surrounding the sample under conditioning. Fluid flow may also be simulated within the sample chamber100. For example, a flow loop may be connected to the sample chamber100to provide flow over a specimen. Flow may also be directed through a specimen, for example, fluid may be directed through a tubular sample (e.g., blood vessel) that is under conditioning within the sample chamber100. As such, for this arrangement the sample chamber100is sealable to allow for fill content and directed flow.

In this arrangement, to allow for the introduction of fluids (or other content), the sample chamber100is sealed to define a chamber volume102within which a specimen104is positioned. The sample chamber100also includes two push rods106,108that allow for the specimen104to be held along an axis (here a vertically oriented axis). Along with assisting with mechanical stimulation (e.g., applying a load, displacement, pressure), the orientation and position of the push rods106,108may be manually changed for adjusting the specimen104. For this particular measurement, the ends of the specimen104are held by a pair of sample grips110,112to allow for a load to be placed on the specimen (along with assisting other types of mechanical conditioning). While the “c-shaped” grips110,112are relatively large compared to the chamber volume102, other types of grips and gripping techniques may be used within the sample chamber100.

The sample chamber100also includes a chamber window114that allows the chamber volume102(and the specimen104under conditioning) to be viewed, of example, during conditioning. Various types of transparent material (e.g., plastics, glass, etc.) may be used to produce the window114while still providing the appropriate structural integrity needed for conditioning with the sample chamber100. Along with allowing the chamber volume102(and the contents of the volume) to be viewed, the chamber window114may also be used for non-intrusive conditioning of the specimen. For example, measurements that implement optical equipment (e.g., a laser, video extensometer, etc.) may utilize the chamber window114for accessing the chamber volume102.

One or more ports may also be included in the sample chamber100for introducing fluids (or other types of contents) into the chamber volume102. For example, one port116may be located at the top of the sample chamber100and another port118may be located at the bottom of the sample chamber. In this arrangement, the ports116,118may be connected to a flow loop for introducing flow through a specimen (e.g., a vascular graft) as described with respect toFIG. 2. Other ports may also be included in the sample chamber100for filling the chamber volume102with one or more fluids (or other types of contents). For example, one or more ports may be incorporated into one or more walls of the sample chamber100or the chamber window114to provide fill fluid into the chamber volume102.

Referring toFIG. 2, the sample chamber100is configured for introducing a fluid flow through a specimen200under conditioning. Typically, to provide such a flow, the specimen200has a tubular geometry such as found with a trachea, a blood vessel, a bladder, etc. or similar geometry such as found with heart valve tissue or various types of tissue substitutes. In this particular arrangement, two fittings202,204(e.g., nozzles, barb fittings, etc.) are respectively connected to two push rods206,208to provide an entrance and exit pathway for the fluid. For example, fluid from a flow loop may be provided to the port116and passed into the specimen200via the push rod206and the fitting202. To return the fluid to the flow loop (or to be passed to another destination), upon exiting the specimen200, the fluid passes through the fitting204and the push rod208(which is in fluid communication with the port118).

Similar to the configuration presented inFIG. 1, a noticeable amount of the chamber volume102is unused when configured for conditioning as shown inFIG. 2. Returning briefly toFIG. 1, while the push rods106,108, the sample grips110,112and the specimen104populate the real estate of the chamber volume102, a portion of the volume remains empty. More noticeably, inFIG. 2, a considerably smaller portion of the chamber volume102is populated with the push rods206,208, the fittings202,204and the specimen200while the remaining portion is empty. Such unused space of the chamber volume102may be of assistance for a technician when inserting and removing contents. For example, the sample chamber100may be designed such that the chamber volume102allows for easy access and rapid mounting of components (e.g., push rods, grips, etc.) and the specimen under conditioning. However, once assembled for conditioning, the empty portion of the chamber volume102may introduce a considerable and undesired cost. For example, conditioning may call for considerably expensive fluid or media to cover the specimen under conditioning. Expensive fill contents such as a nutrient medium may be commercially available or custom produced may be needed for conditioning a specimen. Such contents may include material such as saline solutions, nutrients (e.g., vitamins, amino acids, etc.), pH buffering reagents, growth factors, anti-fungal and anti-bacterial agents and other types of components. In one example, the cost of a nutrient media may exceed $1.00 per milliliter. Accordingly, conditioning four samples in a one liter flow loop volume may cost approximately $1000.00. Thus, by reducing the unused portion of the chamber volume102during conditioning, a considerable cost saving may be realized.

Referring toFIG. 3, a chamber insert300is positioned into the sample chamber100to reduce the chamber volume without interfering with the specimen under conditioning and the devices for holding the specimen within the sample chamber. By reducing the volume, the amount of fluid or media needed to cover the specimen is significantly reduced, thereby reducing overall experimental cost. In this example, the chamber insert300occupies a considerable portion of the chamber volume. However, the portion of the chamber volume used for conditioning the specimen is not significantly encroached upon by the chamber insert300. Rather, the chamber insert300defines a cavity302that surrounds the specimen and the devices for holding the specimen. In this particular example, the sample chamber100is configured for conditioning as shown inFIG. 2, in which the specimen is being held by a pair of push rods and fittings. By defining the cavity302, the amount of fill fluid or media needed to cover a specimen under conditioning is reduced. Further, the cavity302allows fluid to flow through and/or over the specimen under conditioning. For example, the cavity302may be defined by the chamber insert300such that fluid (e.g., nutrient media) is maintained over the specimen and specimen holding devices (e.g., push rods, grips, porous or non-porous compression platens, nozzles, fittings such as barb fittings, three or four point bend fixtures, etc.). Further, the chamber insert300does not substantially come into contact (if at all) with the specimen or the holding devices. In some arrangements, the chamber insert is sufficiently fixed inside the chamber and remains substantially stationary with respect to the sample chamber during mechanical conditioning and/or fluid flow. In other arrangements, the chamber insert may be shaped or produced of materials to allow movement within the sample chamber during mechanical conditioning and/or fluid flow without significantly affecting the specimen e.g., while allowing fluid mixing to be enhanced.

Along with defining the cavity for conditioning, the chamber insert300may also include other features that assist specimen conditioning. For example, an opening304may be included in the chamber insert300to allow for viewing and for granting non-intrusive measurement devices (e.g. a laser micrometer, video extensometer, etc.) access to the specimen under conditioning. In this particular example, the opening304is aligned with the chamber window114of the sample chamber100to allow viewing of the specimen and the holding devices (e.g., push rods, fittings, etc.), however, in other arrangements different orientations, positions and opening sizes may be implemented. Additionally, more than one opening may be incorporated into the chamber insert300to provide viewing and access. For example, a series of relatively small openings may be included in the chamber insert300that are capable of receiving various types of transducers (e.g., pressure transducers) and flow measuring devices (e.g., hot wire, hot films, etc.). In some arrangements, viewing the specimen or specimen holding devices may not be needed and the opening304may be removed from the chamber insert300. In some situations, a plug or other type of cover may be inserted into the opening304, or, a chamber insert may be used that is absent such an opening. By eliminating the opening304, the volume of the sample chamber is further reduced, thereby further reducing the fluid (e.g., nutrient media) needed to fill the chamber. The chamber insert300may also be manufactured such that the material is transparent to allow for viewing the interior of the sample chamber.

One or more implementations and techniques may be used for positioning a chamber insert (or multiple chamber inserts) within a sample chamber. For example, as represented inFIG. 4a, a chamber insert may be positioned within a sample chamber and enclosed by the walls of the sample chamber. A chamber insert may be produced that includes a portion that conforms to a sample chamber. For example, as represented inFIG. 4b, a sample chamber insert is produced (e.g., manufactured) that includes a portion of a sample chamber wall. As such, a portion of the chamber insert may be positioned within a sample chamber to reduce volume of the chamber while another portion of the insert forms a wall of the chamber.

Referring toFIG. 4a, one exemplary chamber insert400is illustrated as being a combination two segments402,404that may be combined before or during insertion into a sample chamber. By segmenting the chamber insert400, the segments402,404may be positioned into the sample chamber with relative ease by a technician. During insertion, the segments402,404may be positioned on opposing sides of the specimen holding device and moved (as indicated with arrows406,408) to form the chamber insert400and surround the holding devices and a specimen. While the chamber insert400is formed from two segments in this example, in some arrangements more than two segments may be produced and combined to form the chamber insert. A chamber insert may also be produced as a single segment that may have mechanical and material properties to allow insertion into a sample chamber. For example, a single piece chamber insert may be produced from one or more flexible materials (e.g., a flexible plastic) that may be physically manipulated for placing the insert into a chamber.

To receive the specimen and holding devices, one or more features may be incorporated into either or both of the segments402,404. For example, each of the segments402,404may be shaped such that when combined, a cavity is formed to receive the specimen and the specimen hold devices. In this particular example, each segment respectively includes a channel410,412that form a cylindrical cavity414upon combining the segments. Along with receiving the specimen and specimen holding devices, in this arrangement, the cylindrical cavity414provides a fluid flow path. In particular, the channels410,412are open at each end of the two segments402,404resulting in the cylindrical cavity414being open at each end and capable of supporting a fluid flow. As such, specimens positioned in the cylindrical cavity414may be immersed in fluid or content (e.g., nutrient media) for measurements. Additionally, by connecting the sample chamber into a flow loop, fluid may be circulated over and/or through the specimen.

Along with defining one or more cavities, other applications may be provided by features incorporated into the segments402,404. For example, features may be incorporated into one or more surfaces of the segments402,404for directing the flow of fluid through the chamber insert400. One or more coatings may be applied to surfaces that form the channels410,412. Incorporated features may also include structures incorporated into the channel surfaces, for example, ridges or fins may be formed (e.g., grooved) into the surfaces for directing fluid flow. As shown in the figure, in one exemplary arrangement, ridges418may be positioned into a parallel orientation to provide a relatively straight fluid flow (e.g., laminar flow) through a portion of the cylindrical cavity414and over the specimen. The parallel ridges may also be oriented and shaped to provide other types of flow. For example, a corkscrew pattern may be incorporated into the parallel ridges so that a spiral flow pattern is provided over the specimen. Structures may also be incorporated for producing a turbulent flow and providing surfaces (e.g., wings, spoilers, large eddy break up devices (LEBUs), etc.) for controlling the flow. A combination of coatings and structures may also be incorporated into the surfaces of channels, for example, a coating that includes series of parallel groves (e.g., riblets) may be applied for flow shaping and control.

Referring toFIG. 4b, rather than being positioned within a sample chamber as a separate structure, a chamber insert may be produced that includes one or more portions of a sample chamber. In this particular example, a chamber insert420includes two segments424,426(similar to the chamber insert segments shown inFIG. 4a) that respectively include wall sections428,430of a sample chamber422. By producing such a chamber insert that includes conforming wall sections, the chamber insert segments424,426form the sample chamber422along with forming the chamber insert420to reduce chamber volume. In this example, the sample chamber422is formed by inserting the chamber insert segments424,426into respective openings432,434. Also, by inserting the segments424,426, a cavity is formed in the sample chamber422that surrounds a specimen and specimen holding devices. For viewing the specimen and specimen holding devices, transparent or semi-transparent material may be incorporated into one (or both) of the chamber insert segments424,426and one (or both) of the corresponding sample chamber wall sections428,430(or both). In some arrangements, a portion of a chamber insert segment (e.g., segment424) may be removed (e.g., cut out) to produce an opening that may be aligned with a transparent portion (e.g., a window) of a sample chamber wall section (e.g., section428) for viewing a specimen. Other features may also be included in the sample chamber422, for example, in this particular arrangement a grip point436is included in the sample chamber to allow access to the interior of the chamber.

Surface features and treatments may also be incorporated that are specific to the fluid being introduced to the specimen (e.g., covering, passing over, etc.). For example, the fluid may include a nutrient media that contains live cellular material. As such, the surface of channels (e.g., channels410,412) may need to be formed of a material that is substantially inert to such cellular material. The surfaces of the channels may have a relatively smooth finish so that cellular material (e.g., individual cells) is not impeded by or lodged in a surface defect (e.g., surface pit, pore, etc.) and possibly contaminate the remaining fluid (and possibly the specimen). In some arrangements, a coating (which is capable of preventing cell adhesion to surfaces) may be applied to one or more chamber insert surfaces so that cells are suspended in the fluid and do not significantly adhere to the surfaces. Exemplary materials that prevent cell adhesion include heparin and Sigmacote.

One or more coatings may also be applied for promoting the adhesion of cells on insert surfaces (e.g., for producing molecules beneficial to the specimen). Such materials may be produced by processing biologic structures so that cells substantially attach to these materials. Adhesion promoting materials include growth factors (e.g., vascular endothelial growth factor), proteins (laminin, fibronectin), peptide sequences (e.g., RGD) and other similar molecules. Chamber insert surfaces may be treated with one or more chemicals (e.g., heparin), coatings, etc. so that blood can be used in a sample chamber without significant coagulation. Further, a chamber insert may have a defined porosity and pore size distribution that promote fluid flow mixing and particular flow profiles. Further, a chamber insert may contain defined pores that are used to encapsulate nutrients for slow release over a period of time (e.g., nutrients encapsulated in degradable materials so that their release is dependent on the material's degradation rate). Relatively inexpensive material may also be used for producing chamber inserts, for example, polystyrenes or other similar material may be used to produce inserts. As such, the chamber inserts may be considered relatively inexpensive and disposable (e.g., may be discarded after one or a few uses).

In some arrangements the insert or portions of the insert may be degradable such that over a period of time (and in some arrangements a controllable period of time), the chamber insert degrades away. Such an arrangement may support measurements during which cell numbers and/or metabolic activity may have significantly increased and higher nutrient medium volumes are needed. In some arrangements, such degradable chamber inserts may include materials with characteristics such as biocompatible, autoclavable, a relatively small amount of surface defects per unit area, etc. Degradable materials include, e.g., polyglycolic acid, polylactic acid, polycaprolactone, etc.

Features may also be incorporated into the insert segments (e.g., segments402,404) for providing access to the specimen and the specimen holding devices. For example, portions of segments may be removed (e.g., cutout) or segments may be created to produce one more openings. Similar to the opening304(shown inFIG. 3), segments (e.g., segment402) may include an opening to allow viewing of and non-intrusive access to the location of the specimen. Features may also include other types of openings or partial openings for accessing the vicinity of the specimen. For example, one opening or an array of openings may be incorporated into one or more of the segments402,404for providing access to measurement devices (e.g., pressure sensors) and flow monitoring devices (e.g., hot films, hot wires, etc.).

Various types of material may used to produce a chamber insert (e.g., chamber insert400) and corresponding segments. One or more synthetic materials such as glass, plastics and thermoplastics may be used to produce the segments (e.g., segments402,404). For example, polyethylene, polypropylene (e.g., TecaPro™ from Boedeker Plastics, Inc of Shiner, Tex.) or other similar plastic may be used. Particular material characteristics may be implemented to produce inserts, for example, non-porous, biocompatible, non-cytotoxic, chemically inert (non-corrosive), sterilizable (preferably by steam sterilization or autoclaving) material may be implemented.

Referring toFIGS. 5 and 6, two implementations of conditioning systems are displayed that include multiple sample chambers similar to the sample chambers shown inFIGS. 1,2and3. In particular, a conditioning system500is presented inFIG. 5and includes four vertically oriented sample chambers. The conditioning system500includes sample chambers configured to condition disc-like samples (e.g., cartilage, bone, meniscus, etc.).FIG. 6presents a conditioning system600that includes a multiple sample chamber along with flow loop equipment. Similar to the sample chamber shown inFIG. 3, a chamber insert may be positioned in one or more of the sample chambers of the conditioning systems500,600to reduce the volume of the respective sample chambers and correspondingly reduce the amount of fill fluid and conditioning cost. Other implementations may also be used, such as conditioning systems described in U.S. patent application Ser. No. 11/780,729, now U.S. Pat. No. 7,587,949, filed Jul. 20, 2007, and U.S. application Ser. No. 12/119,830, now U.S. Pat. No. 7,694,593, entitled “Multi-Sample Conditioning System”, filed May 13, 2008, both of which are herein incorporated by reference.

Other embodiments are within the scope of the following claims. The techniques described herein can be performed in a different order and still achieve desirable results.