Patent Application
20230076661
The present disclosure relates to a microfluidic device, e.g. chip or flow cell, and method of analyzing permeability of a sample membrane, e.g. (epithelial) barrier, (fresh) tissue explant, cell layers, scaffold, or other membranes. For example, a piece of tissue explant may contain different cell types which can be distinguished from cell mono- or double layers, or a suspension of cells injected into a chip.
WO 2012/118799 A2 describes systems and methods for culturing and/or maintaining intestinal cells, tissues and/or organoids in vitro. The cells, tissues and/or organoids cultured can mimic or reproduce natural intestinal epithelial structures and behavior as well as support co-culture of intestinal microflora.
WO 2014/069995 A1 describes a vial for holding a segment of epithelial tissue. More specifically, to a vial which is easy to assemble and allows horizontal alignment of the tissue sample. The prior art further relates to a device comprising the vial, to methods for generating the device, and to a multitude of said devices which allow medium throughput measurements of absorption, transport and/or secretion across an epithelial tissue.
EP 2 233 924 A1 describes a biochip assembly comprising a semi-permeable membrane and an assay method using the biochip assembly for carrying out cell based assays. The ability to monitor migration of biological cells through tight layer of other cells and tissues can be important for understanding of mechanism of diseases and development of therapeutic drugs. In this prior art, there is provided a method for measuring the migration of sample cells in an assembly comprising a plurality of compartments in fluid communication wherein the method comprises introducing analyte into at least one analyte receiving compartment, introducing samples cells into at least one sample cell receiving compartment wherein the sample cells are separated from the analyte by a semipermeable membrane, and the analyte and/or the sample cells are subjected to controlled flow conditions. In this manner the assembly may comprise two compartments in the form of a channel divided into two by a semi-permeable membrane, or a channel and a well/chamber. Alternatively, the assembly may comprise a plurality of compartments in the form of two or more channels, and even two or more channels and well/chambers. The compartments are in fluid communication for at least part of the surface/length of the compartment. In this manner, the analyte receiving compartment is separated from the sample cell receiving compartment by a semi-permeable membrane.
One challenge in existing devices is to mimic the properties of human epithelial cells. For example, epithelial cells are cultured on a substrate to mimic the epithelial tissue in the gut. However, such cultured cells may not possess all intestinal epithelial subtypes and genetic variations of actual epithelial tissue. Another or further challenge may relate to mounting an epithelial tissue sample, e.g. wherein the sample does not sufficiently adhere to the sides of the membrane. For example, as it is difficult to attach the tissue sample to the sides by proliferation (cell growth), leakage may occur. Other or further challenges may relate to reliably mounting and dismounting of membranes between channels inside the device.
Aspects of the present disclosure relate to a microfluidic device for analyzing permeability of substances through a (sample) membrane, e.g. to study different properties of epithelial barriers, such as their permeability to different biological and pharmacological substances. The microfluidic device comprises a housing with flow channels for passing a respective fluid flow, e.g. two parallel flows, between respective connectors. For example, the substances can be dissolved or suspended in at least one of the fluid flows. An access cavity can be used to access the housing to place the membrane, e.g. biological barrier, over a cavity opening. The cavity opening preferably forms an exclusive fluid interconnection between overlapping areas of the flow channels. A clamping ring, preferably forming part of a flow channel, can be used to hold the sample membrane in place over the cavity opening while the membrane is, in use, exposed to the respective fluid flows through the flow channels on either sides of the membrane. The microfluidic device can be used in a system including a pump and respective reservoirs connected to the channels. Use of the microfluidic device or system may include placing the membrane in the cavity opening between the first flow channel and the second flow channel and passing respective flows via the respective reservoir through the flow channels on either sides of the membrane.
These and other features, aspects, and advantages of the apparatus, systems and methods of the present disclosure will become better understood from the following description, appended claims, and accompanying drawing wherein:
Terminology used for describing particular embodiments is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “and/or” includes any and all combinations of one or more of the associated listed items. It will be understood that the terms “comprises” and/or “comprising” specify the presence of stated features but do not preclude the presence or addition of one or more other features. It will be further understood that when a particular step of a method is referred to as subsequent to another step, it can directly follow said other step or one or more intermediate steps may be carried out before carrying out the particular step, unless specified otherwise. Likewise it will be understood that when a connection between structures or components is described, this connection may be established directly or through intermediate structures or components unless specified otherwise.
The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. In the drawings, the absolute and relative sizes of systems, components, layers, and regions may be exaggerated for clarity. Embodiments may be described with reference to schematic and/or cross-section illustrations of possibly idealized embodiments and intermediate structures of the invention. In the description and drawings, like numbers refer to like elements throughout. Relative terms as well as derivatives thereof should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the system be constructed or operated in a particular orientation unless stated otherwise.
In some embodiments, e.g. as shown, the connectors 11a,12a on the same face of the housing may be offset in a lateral direction (X) from a central plane. This may provide more room to place the connectors and/or to connect the outside flow circuit, especially if the flow channels 11,12 run close together in the height direction (Z). In some embodiments, e.g. as shown, the flow channels 11,12 are symmetric before and after the access cavity 13. For example, a path of the channels may be rotation symmetric, as in the embodiment shown, and/or mirror symmetric.
In one aspect, the present disclosure provides a microfluidic device 100 for analyzing permeability of substances through a (sample) membrane M. For example, the substances are disposed in a respective fluid flow F1,F2. Typically, the microfluidic device 100 comprises a housing 10 with flow channels 11,12. In some embodiments, a first flow channel 11 is configured to pass a first fluid flow F1 through the housing 10 between a first input connector 11 and a first output connector 11b. In other or further embodiments, a second flow channel 12 is configured to pass a second fluid flow F2 through the housing 10 between a second input connector 12a and a second output connector 12b.
In a preferred embodiment, the device comprises an access cavity 13 extending from outside into the housing 10 through the first flow channel 11 and into the second flow channel 12. Accordingly, the cavity can be used for accessing an inside of the housing 10 to place the membrane M over a cavity opening 13i. Most preferably, the cavity opening 13i forms an (exclusive) fluid interconnection between overlapping areas of the flow channels 11,12.
In a preferred embodiment, the access cavity 13 can be opened and/or closed off by a cap 15. Most preferably, the cap 15 can be reversibly removed to access the cavity and, e.g., place or replace the membrane M. For example, the cap 15 and/or housing comprises a resilient material such as rubber there between the seal the cap to the housing. Also other resilient structures can be used, or the cap can be screwed to the housing.
In one embodiment, e.g. as shown, the flow channels 11,12 have a channel width Wh (in the lateral direction X transverse to the main flow direction Y) directly before and/or after the cavity opening 13i which channel width Wh is larger than a cross-section diameter Wi of the cavity opening 13i between the flow channels 11,12, e.g. larger by at least a factor 1.1, preferably at least a factor 1.2, or even more than a factor 1.3. For example, the cross-section diameter Wi of the cavity opening 13i in the shown embodiment is around 5.5 mm, while the channel width Wh directly before the cavity opening 13i is around 7 mm. The wider the flow channels 11,12 before and/or after the cavity opening 13i, the more even the flow across the membrane.
In another or further embodiment, the flow channels 11,12 start with a first channel width Wg at a side of the input and/or output connectors, and gradually widen to a second channel width Wh towards the cavity opening 13i, wherein the second channel width Wh is larger than the first channel width Wg by at least a factor two, three, or more. For example, the initial channel width Wh can be similar to the channel height (not indicated here), e.g. in the shown embodiment around 1 mm, while the channel width Wh directly before the cavity opening 13i can be around 7 mm. By gradually widening the width of the channel, a more predictable/even flow can be realized across the membrane. For example, the gradual widening can be quantified as the increase in width (ΔW) per unit length (ΔL) along a direction (Y) of the flow (through a center of the channel), wherein the ratio (ΔW/ΔL) is preferably less than one. For example, in the shown embodiment (Wh−Wg)/Lgh≈(7 mm−1 mm)/10 mm=0.6.
In some embodiments, a width Wh of the flow channels 11,12 (here in direction X), at least directly before the cavity opening 13i is much larger than a respective height of the flow channels 11,12 (here in direction Z), e.g. larger by at least a factor two, three, four, five or more. For example, in the shown embodiment, the width Wh is about seven times larger than the height (not indicated here). The smaller the height compared to the width of the channels at the position of overlap, the more membrane surface may be covered by the flow for interaction with its components, while not needing to increase total flow rate.
In one embodiment, the housing 10 extends with a cavity seat 13s forming a platform around the cavity opening 13i between the overlapping areas of the flow channels 11,12 to directly or indirectly hold the membrane M between the cavity seat 13s and the clamping ring 14. For example, the membrane M can be placed directly on the cavity seat 13s. For example, the clamping ring 14 may directly clamp down on the membrane M. Preferably though a sealing ring 16 is disposed on either one or both sides of the membrane M. In one embodiment, e.g. as shown, at least one sealing ring 16 is, in use, disposed between the membrane M and the clamping ring 14. This may improve sealing and/or prevent the clamping ring to damage (e.g. cut into) the membrane M. Also other or further structures can be disposed between the clamping ring 14 and the membrane M and/or between the membrane M and the cavity seat 13s. For example, a mesh can be provided to help further support the membrane M. In one embodiment, the cavity opening 13i on one side of the membrane M and a ring opening 14i through the clamping ring 14 on another side of the membrane M are configured to, in use, expose the membrane M to the respective fluid flows F1,F2 in the flow channels 11,12.
In a preferred embodiment, the clamping ring 14 is configured to form part of the first flow channel 11. For example, the clamping ring 14 is configured to guide the first fluid flow over the clamping ring 14 between a bottom 15b of the cap 15 (sealing the access cavity 13) and the clamping ring 14 to the ring opening 14i. In some embodiments, the structures surrounding the openings are relatively thin near the opening, preferably comprising a gradual transition from the flow channels 11,12. In one embodiment, the clamping ring 14 has an inner thickness at its opening 14i along its inner diameter, and outer thickness second thickness at its outer diameter, wherein the outer thickness is more than the inner thickness, e.g. by at least a factor two. Preferably, the clamping ring 14 comprises a sloped and/or rounded transition 14r between its inner and outer diameters getting gradually thinner towards its center. Accordingly, the flow in the first flow channel 11 can be steered to gradually approach the membrane M on the top
In other or further embodiments, the cavity seat 13s has an inner thickness at its opening 13i along its inner diameter, and outer thickness further from the opening, wherein the outer thickness is more than the inner thickness, e.g. by at least a factor two. Preferably, the cavity seat 13s comprises a sloped and/or rounded transition 11r getting gradually thinner towards the cavity opening 13i. Accordingly, the flow in the second flow channel 12 can alternatively, or additionally, be steered to gradually approach the membrane M on the bottom
In one embodiment, the connection structure 13c of the housing inside the access cavity 13 surrounds the cavity seat 13s. In another or further embodiment, the connection structure 13c of the housing inside the access cavity 13 comprises a set of clamping fingers with hooks configured to clamp around a rim of the clamping ring 14. In some embodiments, each of the fingers is configured to pivot radially outward, to allow insertion of the clamping ring, and then return inward with the hooks engaging a corresponding structure, e.g. rim, around the clamping ring 14. For example, at least two, preferably three, four, or more clamping fingers are located circumferentially around the cavity opening 13i. In some embodiments, discussed later with reference to
In one embodiment, the connection structure 13c of the housing, e.g. clamping fingers, protrude from the cavity seat 13s. In another or further embodiment, a sealing ring 16 is disposed together with the membrane M between the cavity seat 13s and the clamping ring 14. While the clamping ring may comprise a relatively hard material, the sealing ring 16 preferably comprises a (more) resilient material such as rubber. In some embodiments, the sealing ring 16 when held by the clamping ring 14 is configured to prevent a passage of fluid around the sealing ring 16 ring. In other or further embodiments, the sealing ring 16 is configured to exclusively pass fluid through an opening 16i in the sealing ring 16 (which opening is, in use, covered by the membrane M, so substances in the fluid may permeate there through).
Preferably, the ring opening 14i through the clamping ring 14 and the cavity opening 13i between the flow channels 11,12 have a substantially matching interconnection diameter Wi, e.g. deviating less than thirty percent, preferably less than twenty, or less than ten percent. Similar for the opening 16i through the sealing ring 16 which is preferably disposed there between. While in a preferred embodiment, the openings are circular, also other shapes can be envisaged. Typically, the sealing ring 16 is configured to (in use) abut the membrane M. In some embodiments, e.g. as shown in
In one embodiment, a first channel height M1 between a position of the membrane M clamped inside the device and opposing wall of the first flow channel 11 is similar to a second channel height M2, opposite the membrane M between the position of the membrane M and opposing wall of the second flow channel 12 within a factor two, preferably within a factor one-and-half. The more similar the respective heights of the channels on either sides of the membranes, the more similar the respective maximum flow distance and corresponding efficiency of parts of the flow interacting with the membrane.
Also other or further components can be disposed between the membrane M and the cavity seat 13s and/or between the sealing ring 16 and the cavity seat 13s. In a preferred embodiment, a mesh 17 is provided which abuts the membrane M to improve is structural integrity. For example, the mesh 17 can provide a relatively open structure which does not substantially affect permeability of the membrane M. Preferably, the mesh is provided at least below the membrane M. Alternatively, or additionally, a mesh can be provided above the membrane M.
In some embodiments, the flow distance M1 to the membrane can be further decreased, e.g. by a shape of the channel 14a protruding towards the membrane. In one embodiment, a respective channel height M1,M2 between a position of the membrane M clamped inside the device and opposing wall of the respective first and/or second flow channel 11,12 is less than one millimeter, preferably less than 0.8 mm, less then 0.6 mm, or even less than half a millimeter. The smaller the channel height M1,M2 at the position of the membrane, the closer the flow distance and the more effective the flow may interact with the membrane.
In other or further embodiments, a respective channel height M1,M2 of a respective flow channel 11,12 at the position of the membrane M is similar to a channel height H1,H2 of the respective flow channel 11,12 before and/or after the clamping ring 14, e.g. within a factor two, preferably within a factor one-and-half or less. Keeping the channel height relatively constant may promote a more predictable flow.
Aspects of the present disclosure can be embodied as a system comprising the microfluidic device 100 as described herein. In one embodiment, the system comprises a pump 110, preferably peristaltic. In another or further embodiment, the system comprises at least a first and second reservoir 121,122. Channels or tubes can be used to interconnect the microfluidic device 100, pump 110, and reservoirs 121,122 (e.g. with reference to
The microfluidic device 100 or system 1000 as described herein can be used e.g. for analyzing permeability of substances through a membrane M. In use, the membrane M is placed in the cavity opening 13i between the first flow channel 11 and the second flow channel 12. In some embodiments, a first flow F1 is passed via the first reservoir 121 through the first flow channel 11, and a second flow F2 is passed via the second reservoir 122 through the second flow channel 12. For example, the substances can be disposed in at least one of the fluid flows F1,F2, e.g. in different amounts. In some embodiments, a respective content of the substances in the first and/or second reservoir 121 is measured and/or monitored to determine an exchange of the substances through the membrane M.
Typical flows may e.g. be set between one and hundred milliliter per hour e.g. depending on channel height. For example, components can be added to the first reservoir 121 and measured in the second reservoir 122, e.g. by taking a sample from the reservoir. For example, the first reservoir 121 can be used to act as (emulate) a lumen while the second reservoir 122 can be used to act as a blood vessel. For example, the components may include nutritional components, medicine, et cetera. For example, the membrane M comprises a tissue sample, scaffold e.g. 3D structure with cells, or other membrane, e.g. plastic or polyester. Accordingly the microfluidic device 100 can or system 1000 be used to test various membranes.
In interpreting the appended claims, it should be understood that the word “comprising” does not exclude the presence of other elements or acts than those listed in a given claim; the word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements; any reference signs in the claims do not limit their scope; several “means” may be represented by the same or different item(s) or implemented structure or function; any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise. Where one claim refers to another claim, this may indicate synergetic advantage achieved by the combination of their respective features. But the mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot also be used to advantage. The present embodiments may thus include all working combinations of the claims wherein each claim can in principle refer to any preceding claim unless clearly excluded by context.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20153565.5 | Jan 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/NL2021/050040 | 1/22/2021 | WO |
