Patent Description:
Biological therapies are increasingly viable methods for treating peripheral artery disease, aneurysm, heart disease, Alzheimer's and Parkinson's diseases, autism, blindness, diabetes and other pathologies. With respect to biological therapies in general, cells, viruses, viral vectors, bacteria, proteins, antibodies and other bioactive moieties may be introduced into a patient by surgical or interventional methods that place the bioactive moiety into a tissue bed of a patient. Often the bioactive moieties are first placed in a device that is then inserted into the patient. Alternatively, the device may be inserted into the patient first with the bioactive moiety added later.

These devices are often implanted temporarily into the patient. However, even temporary devices have tissue ingrowth that can make removing the devices from the surrounding tissue difficult. Conventional removal of the devices, for example, by cutting the surrounding tissue, can be traumatic to the tissue. In addition, these procedures may result in patient discomfort as well as the inability to re-use the same tissue for future procedures. Thus, there is a need for implantable devices that encapsulate cells and/or other biological moieties, where the devices are atraumatically removable from a patient. <CIT> discloses a cell encapsulation device comprising:a pouch comprising: opposed first and second ends; first and second composite layers extending between the opposed first and second ends, wherein the first composite layer includes: a first cell permeable layer extending between the opposed first and second ends; and a first cell retentive layer extending between the opposed first and second ends; and wherein the second composite layer includes: a second cell permeable layer extending between the opposed first and second ends; and a second cell retentive layer extending between the opposed first and second ends; and a lumen extending through the cell encapsulation device from the first end to the second end; a reservoir positioned between the first and second composite layers, the reservoir contacting the first cell retentive layer; at least one port in fluid communication with the reservoir.

The terms "disclosure," "the disclosure," "this disclosure" and "the present disclosure," as used in this document, are intended to refer broadly to all of the subject matter of this patent application and the claims below. Statements containing these terms should be understood to not limit the subject matter described herein or to limit the meaning of the scope of the patent claims below. This summary is a high-level overview of various aspects of the disclosure and introduces some of the concepts that are further detailed in the Detailed Description section below. The subject matter should be understood by reference to the appropriate portions of the entire specification, any or all drawings, and each claim.

The present invention relates to a cell encapsulation device as set forth in the appended claims. The method of using the device does not form part of the invention. Embodiments of the present disclosure relate to therapeutic devices that include a pouch having opposed first and second ends. The pouch includes first and second composite layers extending between the opposed first and second ends. The first composite layer includes a first cell permeable layer extending between the opposed first and second ends and a first cell retentive layer extending between the opposed first and second ends. The pouch also includes a reservoir positioned between the first and second composite layers, the reservoir contacting the first cell retentive layer. The pouch also includes at least one port in fluid communication with the reservoir. The pouch also includes a removal element configured to operably engage the first end of the pouch, so as to cause the first end to be moveable towards the second end of the pouch by eversion.

In some embodiments, each of the first and second composite layers comprises a plurality of wrinkles.

In some embodiments, first cell permeable layer has a pore size sufficient to permit growth of vascular tissue therethrough.

In some embodiments, the pore size is greater than <NUM> microns as measured by porometry.

In some embodiments, the first cell retentive layer has a pore size sufficient to prevent ingrowth of vascular tissue.

In some embodiments, the pore size is less than <NUM> micron, as measured by porometry.

In some embodiments, at least one of the first cell permeable layer and the first cell retentive layer comprises an expanded fluoropolymer.

In some embodiments, the second composite layer comprises a second cell permeable layer extending between the opposed first and second ends and a second cell retentive layer extending between the opposed first and second ends.

Embodiments of the present disclosure also relate to a method including engaging a removal element configured to operably engage a first end of a therapeutic device implanted in a tissue pocket, wherein the implanted therapeutic device and the tissue pocket define a plane. The method also includes exerting a tensile force on the removal element in a first direction parallel to the plane. The method also includes moving the removal element along the first direction to move a first end of the implanted therapeutic device towards a second end of the implanted therapeutic device opposite the first end such that the implanted therapeutic device is peeled away from the tissue pocket, wherein the moving step everts the implanted therapeutic device to remove the implanted therapeutic device from the tissue pocket atraumatically.

In some embodiments, the therapeutic device includes a pouch including opposed first and second ends. The pouch includes first and second composite layers extending between the opposed first and second ends. The first composite layer includes a first cell permeable layer extending between the opposed first and second ends. The first composite layer also includes a first cell retentive layer extending between the opposed first and second ends. The pouch also includes a reservoir formed between the first and second composite layers. The reservoir contacts the first cell retentive layer. The pouch also includes at least one port in fluid communication with each reservoir. The therapeutic device also includes a removal element configured to operably engage the first end of the pouch, so as to cause the first end to be moveable towards the second end by eversion.

In some embodiments, each of the first composite layer and the second composite layer comprises a plurality of wrinkles.

In some embodiments, the method further includes moving the therapeutic device from a first relaxed state in which the plurality of wrinkles formed the at least one of the first composite layer and the second composite layer engages tissue in a tissue pocket, to a second extended state, in which at least some of the plurality of wrinkles are stretched apart, so as to disengage a portion of the tissue from the at least some wrinkles. The moving step includes a plurality of discrete individual movements, whereby the tissue is incrementally disengaged from the plurality of wrinkles of the pouch so that the pouch is removed from the tissue pocket atraumatically.

Embodiments of the present disclosure also relate to a therapeutic device including opposed first and second ends, wherein the opposed first and second ends define a longitudinal axis therebetween. The therapeutic device also includes a first composite layer extending between the first and second ends. The first composite layer includes a first plurality of wrinkles. The therapeutic device also includes a second composite layer extending between the first and second ends. The second composite layer includes a second plurality of wrinkles. The therapeutic device also includes a reservoir formed between the first and second composite layers, the reservoir having a length, a width and a depth. The therapeutic device also includes at least one port in fluid communication with the reservoir. The therapeutic device is moveable between a first relaxed state, in which the first plurality of wrinkles and the second plurality of wrinkles extend in a direction generally perpendicular to the longitudinal axis, and a second extended state, in which the first plurality of wrinkles and the second plurality of wrinkles are configured to be stretched between the first and second ends, so as to be generally parallel with the longitudinal axis.

In some embodiments, at least one of the first composite layer and the second composite layer comprises a cell permeable layer extending between the opposed first and second ends and a cell retentive layer extending between the opposed first and second ends.

Embodiments of the present disclosure also relate to method including engaging a first end of a therapeutic device implanted in a tissue pocket, wherein the implanted therapeutic device and the tissue pocket define a plane. The method also includes exerting a tensile force on the first end in a first direction parallel to the plane to move the therapeutic device from a first relaxed state in which a plurality of wrinkles formed on the therapeutic device engages tissue in the tissue pocket, to a second extended state, in which at least some of the plurality of wrinkles are stretched apart, so as to disengage a portion of the tissue from the at least some wrinkles. The moving step includes a plurality of discrete individual movements, whereby the tissue is incrementally disengaged from the plurality of wrinkles of the pouch so that the pouch is removed from the tissue pocket atraumatically.

In some embodiments, the therapeutic device includes opposed first and second ends. The opposed first and second ends define a longitudinal axis therebetween. The therapeutic device also includes a first composite layer extending between the first and second ends. The first composite layer includes a first plurality of wrinkles. The therapeutic device also includes a second composite layer extending between the first and second ends. The second composite layer includes a second plurality of wrinkles. The therapeutic device also includes a reservoir formed between the first and second composite layers, the reservoir having a length, a width and a depth. The therapeutic device also includes at least one port in fluid communication with the reservoir. The therapeutic device is moveable between the first relaxed state, in which the first plurality of wrinkles and the second plurality of wrinkles extend in a direction generally perpendicular to the longitudinal axis, and the second extended state, in which the first plurality of wrinkles and the second plurality of wrinkles are configured to be stretched between the first and second ends, so as to be generally parallel with the longitudinal axis.

In some embodiments, at least one of the first composite layer and the second composite layer is a cell permeable layer.

In some embodiments, at least one of the first composite layer and the second composite layer is a cell retentive layer.

The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments, and together with the description serve to explain the principles of the present disclosure.

Persons skilled in the art will readily appreciate that various aspects of the present disclosure can be realized by any number of methods and apparatus configured to perform the intended functions. It should also be noted that the accompanying drawing figures referred to herein are not necessarily drawn to scale, but may be exaggerated to illustrate various aspects of the present disclosure, and in that regard, the drawing figures should not be construed as limiting. In addition, the term "therapeutic device" and "device" may be used interchangeably herein. It is to be appreciated that the term "therapeutic device" may also be used interchangeably with term "cell containment device" herein.

Described herein are therapeutic devices for encapsulating biological moieties where the biological devices are implanted into a patient, such as into a tissue bed, to provide biological therapy. Therapeutic devices may include a cell encapsulation device, a drug delivery device, or a gene therapy device. Also described herein are methods for forming the devices and for introducing the biological moieties into the devices. In some embodiments, the therapeutic device is a pouch formed of composite layers. Each of the composite layers has a porous polymeric layer for the retention of biological moieties and a porous layer that enables vascularization. The cell retentive and cell permeable layers have different porosities, and may include or be formed of the same material or different materials. In some embodiments, the cell retentive layer has a porosity that is less than the porosity of the cell permeable layer. The composite layers are spaced apart from one another to define at least one reservoir space for the retention of biological moieties.

In some embodiments, biological moieties suitable for encapsulation and implantation using the devices described herein include cells, viruses, viral vectors, gene therapies, bacteria, proteins, polysaccharides, antibodies and other bioactive moieties. For simplicity, hereafter the biological moiety is referred to as a cell, but nothing in this description limits the biological moieties to cells or to any particular type of cell, and the following description applies also to biological moieties that are not cells. In some embodiments, various types of prokaryotic cells, eukaryotic cells, mammalian cells, non-mammalian cells, and/or stem cells may be used with the cell encapsulation devices of the present disclosure.

In some embodiments, the cells are microencapsulated within a biomaterial of natural or synthetic origin, including, but not limited to, a hydrogel material. In some embodiments, the cells secrete a therapeutically useful substance. In some embodiments, such substances include hormones, growth factors, trophic factors, neurotransmitters, lymphokines, antibodies, or other cell products which provide a therapeutic benefit to the device recipient. Examples of such therapeutic cell products include, but are not limited to, insulin, growth factors, interleukins, parathyroid hormone, erythropoietin, transferrin, and Factor VIII. In some embodiments, non-limiting examples of suitable growth factors include vascular endothelial growth factor, platelet-derived growth factor, platelet-activating factor, transforming growth factors, bone morphogenetic protein, activin, inhibin, fibroblast growth factors, granulocyte-colony stimulating factor, granulocyte-macrophage colony stimulating factor, glial cell line-derived neurotrophic factor, growth differentiation factor-<NUM>, epidermal growth factor and combinations thereof. It is to be appreciated that throughout this disclosure the terms "cell" or "cells" could be replaced by "biological moiety" or "biological moieties," respectively.

An eversion method for removing a therapeutic device for encapsulating cells is described herein. In some embodiments, the therapeutic device is implanted into a tissue of a patient to be treated. After the treatment is complete, or when removal is otherwise required, the therapeutic device may be removed from the tissue of the patient by a tensile force to minimize or avoid trauma to the tissue integrated into device and/or surrounding the device. In at least one embodiment, a removal element of the device is engaged, for example, by a device removal tool. A tensile force is exerted on the removal element by the device removal tool such that a first end of the therapeutic device is everted inwardly through itself toward a second end of the therapeutic device. As the first end of the therapeutic device is pulled toward the second end, the therapeutic device is atraumatically removed (e.g., peeled) from the surrounding tissue and may then be withdrawn from of the patient. As used herein, "atraumatically removed" is meant to denote removal that minimizes or avoids trauma to tissue.

One embodiment of a therapeutic device for encapsulating cells is illustrated in <FIG>. The therapeutic device is scalable in that it can easily be configured throughout a range of sizes (e.g., perimeters) so that the device can be used to house cells while ensuring both the survival and function of these cells. According to an embodiment, the therapeutic device <NUM> includes a pouch <NUM> and a removal element <NUM> attached thereto. The pouch <NUM> extends from a first end <NUM> to a second end <NUM>. In some embodiments, the pouch <NUM> may be tubular in shape. However, the pouch may be any other shape, such as, for example, substantially planar, depending on the anatomical location of the implant. The pouch <NUM> includes a first composite layer <NUM> and a second composite layer <NUM>. A reservoir <NUM> is formed between the first and second composite layers <NUM>, <NUM>. The reservoir <NUM> is a contained space where cells are housed and is accessible by at least one port <NUM>, which is in fluid communication with the reservoir <NUM>. A periphery <NUM> of the pouch <NUM> is sealed up to the location of the port <NUM>. In an exemplary embodiment, a lumen <NUM> extends through the pouch <NUM>, as depicted in <FIG>. It is to be noted that the figures show a lumen <NUM> with a diameter that is exaggerated to show a device removal tool reaching therethrough. However, the device removal tool may only need to slip through the lumen <NUM> and thus, the lumen <NUM> does not need to be held "open". Furthermore, the diameter may be just large enough for the device removal tool to be inserted therein. In some embodiments, the tool will create its own space through the lumen <NUM> as it is inserted therethrough. The removal element <NUM> of the therapeutic device <NUM> is attached to the first end <NUM> of the pouch <NUM> for atraumatic removal of the therapeutic device <NUM> by eversion.

As depicted in <FIG>, in some embodiments, the first composite layer <NUM> is a composite layer that includes a cell permeable layer <NUM> and a cell retentive layer <NUM> disposed adjacent to the cell permeable layer <NUM>. Similarly, the second composite layer <NUM> is a composite layer that also includes a cell permeable layer <NUM> and a cell retentive layer <NUM>. The cell retentive polymeric layer is impervious to cell ingrowth. The cell permeable layer permits the growth of vascular tissue into and through the pores of the cell permeable layer as far as the cell retentive layer. In some embodiments, the cell permeable layers <NUM>, <NUM> of the first and second composite layers <NUM>, <NUM>, respectively, are formed of the same material. In other embodiments, the cell permeable layers <NUM>, <NUM> are formed of different materials. Both of the cell permeable layers <NUM>, <NUM>, are cell permeable layers that are sufficiently porous to permit the growth of vascular tissue <NUM> from a patient into and through the pores of the cell permeable layers <NUM>, <NUM>, as depicted in <FIG>. The ingrowth of vascular tissues through the cell permeable layer facilitates nutrient transfer from the patient to the cells encapsulated in the therapeutic device. However, ingrowth of vascular tissues does not extend through the cell retentive layer.

In some embodiments, the cell permeable layer <NUM>, <NUM> have an average pore size of less than <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns, as measured by porometry. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns.

In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell permeable layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns.

Various cell types can grow into the cell permeable layers of a porous material of the therapeutic device <NUM> as described herein. The predominant cell type that grows into a porous material depends primarily on the implantation site, the composition and permeability of the material, and any biological factors, such as, for example, cytokines and/or cell adhesion molecules that may be incorporated in the material or introduced through porous material(s). In some embodiments, vascular endothelium is the predominant cell type that grows into a porous material for use in a cell encapsulation device. Vascularization of the porous material by a well-established population of vascular endothelial cells in the form of a capillary network <NUM>, as depicted in <FIG>, is encouraged to occur as a result of neovascularization of the material from tissues of a patient into and across the thickness of the material very close to the interior surface of the device <NUM>, but not across the cell retentive layer.

The cell retentive layer and the cell permeable layer should each be compliant enough to allow the therapeutic device to fold on itself during the eversion process. Thus, in some embodiments, vascularization of the cell permeable layer is permitted only to a predetermined degree so as to not interfere with the compliance of the therapeutic device.

The cell retentive layers <NUM>, <NUM> are impervious to cell ingrowth and thus, are cell retentive layers. Both cell retentive layers <NUM>, <NUM> have an average pore size that is sufficiently small so as to prevent vascular ingrowth.

In some embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is less than <NUM> microns. In some embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns, as measured by porometry. In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns.

In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns. In other embodiments, the average pore size of the cell retentive layers <NUM>, <NUM> is from <NUM> microns to <NUM> microns.

A small pore size allows the cell retentive layers <NUM>, <NUM> to function as cell retentive layers to keep cells disposed in the reservoir <NUM> inside the therapeutic device <NUM>. However, this small pore size allows nutrients and other biomolecules to enter and cell waste and therapeutic products to exit. These cell retentive layers <NUM>, <NUM> are referred to as cell retentive layers.

In some embodiments, the cell permeable layers <NUM>, <NUM> and/or the cell retentive layers <NUM>, <NUM> include, but are not limited to, alginate, cellulose acetate, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, panvinyl polymers such as polyvinyl alcohol, chitosan, polyacrylates such as polyethylene-co-acrylic acid, agarose, hydrolyzed polyacrylonitrile, polyacrylonitrile copolymers, polyvinyl acrylates such as polyethylene-co-acrylic acid, porous polytetrafluoroethylene (PTFE), porous modified polytetrafluoroethylene polymers, porous tetrafluoroethylene (TFE) copolymers, porous polyalkylenes such as porous polypropylene and porous polyethylene, porous polyvinylidene fluoride, porous polyester sulfone (PES), porous polyurethanes, porous polyesters, and copolymers and combinations thereof. In some embodiments, materials useful as one or both of the cell permeable layer(s) include biomaterial textiles.

In some embodiments, the cell permeable layers <NUM>, <NUM> and/or the cell retentive layers <NUM>, <NUM> may include porous polyvinylidene fluoride (PVDF) as taught in <CIT>. , porous poly (p-xylylene) (ePPX) as taught in <CIT>, porous ultra-high molecular weight polyethylene (eUHMWPE) as taught in <CIT>, porous ethylene tetrafluoroethylene (eETFE) as taught in <CIT>, vinylidene fluoride-co-tetrafluoroethylene or trifluoroethylene [VDF-co-(TFE or TrFE)] polymers as taught in <CIT>, and copolymers and combinations thereof, as well as woven or non-woven collections of fibers or yarns, or fibrous matrices, either alone or in combination.

In some embodiments, the cell permeable layers <NUM>, <NUM> and/or the cell retentive layers <NUM>, <NUM> are expanded fluoropolymer membranes. For example, the cell permeable layers <NUM>, <NUM> and/or the cell retentive layers <NUM>, <NUM> may include expanded polytetrafluorethylene (ePTFE) or expanded modified polytetrafluoroethylene. In some embodiments, the cell permeable layers <NUM>, <NUM> and/or the cell retentive layers <NUM>, <NUM> are expanded polytetrafluoroethylene membranes (e.g., an ePTFE membrane).

In some embodiments, one or both of the cell retentive layers <NUM>, <NUM> and the cell permeable layers <NUM>, <NUM> of the therapeutic device <NUM> is made, primarily or entirely, of a porous material having selective sieving and/or porous properties. In some embodiments, the porous material controls the passage of solutes, biochemical substances, viruses and cells, for example, through the material, primarily based on size. Non-limiting example of porous materials include, but are not limited to, one or more of the materials set forth above for the inner and outer layers, including biomaterial textiles.

In an embodiment, the therapeutic device <NUM> does not include composite layers. Instead, the therapeutic device includes first and second cell permeable layers. In such an embodiment, the cells to be inserted into the therapeutic device <NUM> are microencapsulated, which provides isolation for the cells from the host immune response but allows the cells to receive nutrients, etc. (e.g., the cells are able to obtain nutrients and other biomolecules from the environment outside of the device <NUM> and expel waste products and therapeutic substances). In some embodiments, the cells may be microencapsulated within a biomaterial of natural or synthetic origin including, but not limited to, a hydrogel.

Turning to <FIG>, and as noted above, the reservoir <NUM> is formed between the first composite layer <NUM> and the second composite layer <NUM> of the pouch <NUM>. Specifically, the reservoir <NUM> is formed between the cell retentive layers <NUM>, <NUM> of the pouch <NUM>. As used herein, the term "reservoir" is meant to define the total area within the therapeutic device <NUM> between a first cell retentive layer and a second cell retentive layer and within the periphery of the therapeutic device <NUM> where the placement of cells (or where the cells reside). The reservoir <NUM> may take numerous configurations such as, for example, a lane or a geometric shape (e.g., the general form of a rectangle, circle, square, semi-circle, semi-oval, etc.).

The reservoir <NUM> is configured to hold cells <NUM> within the therapeutic device <NUM>, as depicted in <FIG>, to allow the cells to secrete a therapeutically useful substance which provides biological therapy to a patient. In some embodiments, the cells <NUM> are introduced into the reservoir <NUM> of the therapeutic device <NUM> through one or more port(s) <NUM> that are fluidly connected to the reservoir <NUM>. The port(s) <NUM> may be positioned anywhere along the perimeter of the therapeutic device <NUM>, so long as they are in fluid communication with the reservoir <NUM> and accessible from an exterior of the therapeutic device <NUM>. In some embodiments, the port(s) <NUM> is located at a periphery of the therapeutic device <NUM>. In some embodiments, the port(s) <NUM> extend through the sealed periphery between the first composite layer <NUM> and the second composite layer <NUM> of the sealed pouch <NUM> so that the cells are introduced into the reservoir <NUM> of the pouch <NUM> through an opening of the pouch material.

In some embodiments, the cells <NUM> are introduced in the form of a suspension or slurry in a medium. The cells <NUM> may be individual cells, cell aggregates, or cell clusters. In some embodiments, the medium may be a cell culture or cell growth medium, optionally including desired nutrients and/or other biomolecules. In some embodiments, insertion of cells through the port <NUM> may be accomplished by a syringe.

The cells <NUM> may be introduced into the reservoir <NUM> prior to or after insertion of the therapeutic device <NUM> into a patient. For example, the therapeutic device <NUM> may be inserted into a patient and allowed to vascularize such that vascular tissue grows into a vascularizing layer of the device <NUM>. The cells <NUM> may then be added while the therapeutic device <NUM> is in vivo. Alternatively, the cells <NUM> may be added to the therapeutic device <NUM> prior to insertion of the therapeutic device <NUM> into a tissue bed of the patient.

As previously noted, the therapeutic device <NUM>, in some embodiments, includes a pouch <NUM>. In some embodiments, the pouch may be tubular in shape. The pouch <NUM> includes a hollow lumen <NUM> extending therethrough from the first end <NUM> of the pouch <NUM> to the second end <NUM> of the pouch <NUM>. As depicted in <FIG>, an outer surface <NUM> of the cell permeable layer <NUM> of the first composite layer <NUM> forms an outer wall of the pouch <NUM>. Additionally, the lumen <NUM> is defined by a lumen-facing surface <NUM> of the cell permeable layer <NUM> of the second layer <NUM>, as depicted in <FIG>.

Although <FIG> depict a lumen <NUM> with an exaggerated perimeter relative to the size of the pouch <NUM>, a perimeter of the lumen <NUM> may be very small or, in some embodiments, substantially nonexistent such that opposing sides of the lumen-facing surface <NUM> are touching. In some embodiments, the lumen <NUM> has a perimeter of, for example, from <NUM> to <NUM>. In other embodiments, the lumen has a perimeter of from <NUM> to <NUM>. In other embodiments, the lumen has a perimeter of from <NUM> to <NUM>. In other embodiments, the lumen has a perimeter of from <NUM> to <NUM>. In other embodiments, the lumen has a perimeter of from <NUM> to <NUM>.

In other embodiments, the lumen has a perimeter of from <NUM> to <NUM>. In other embodiments, the lumen has a perimeter of from <NUM> to <NUM>. In other embodiments, the lumen has a perimeter of from <NUM> to <NUM>. In other embodiments, the lumen has a perimeter of from <NUM> to <NUM>.

In order to remove the therapeutic device <NUM> atraumatically, the device <NUM> includes a removal element <NUM> attached to the first end <NUM> of the pouch <NUM>. The removal element <NUM> allows the therapeutic device <NUM> to be removed via a tangential force rather than a shear force, as will be described in further detail below. The removal element <NUM> may be any structure, integral or attached to the pouch <NUM>, which will transmit a tensile force to the first end <NUM> of the pouch <NUM>. In some embodiments, as depicted in <FIG>, the removal element <NUM> is a pull tab. In other embodiments, the removal element <NUM> comprises a filament, string, ribbon, tube, suture, sheet or other longitudinal element. The removal element <NUM> is biocompatible and may be metallic or a polymeric material. In some embodiments, the removal element <NUM> comprises ePTFE or another strong, inert, biocompatible material(s). The removal element <NUM>, in some embodiments, is attached to the second composite layer <NUM> of the therapeutic device <NUM>. In some embodiments, the removal element <NUM> is attached to the pouch by tying, adhesion or the use of fastener(s). In other embodiments, the removal element <NUM> is formed as an integral portion of the pouch <NUM>. The integral removal element <NUM> may eliminate failure of the connection point between the pouch <NUM> and the removal element <NUM> in other modes of "attachment". In some embodiments, as depicted in <FIG>, the removal element <NUM> extends from the first end <NUM> of the pouch <NUM> and into the lumen <NUM> to be accessed by a device removal tool <NUM>. Specifically, the device removal tool <NUM> is inserted into the lumen <NUM> from the second end <NUM> of the pouch <NUM> to grasp the removal element <NUM>. Thus, a force may be exerted on the removal element <NUM> through the lumen <NUM> to cause the device <NUM> to be removed by eversion, as will be described in further detail below.

In a method of use, depicted in <FIG>, the therapeutic device <NUM> is implanted within a pocket of tissue <NUM> of the patient. The therapeutic device <NUM> may be implanted into the patient prior to or after the introduction of the cells <NUM> into the reservoir <NUM>. Once the therapeutic device is no longer needed, the therapeutic device <NUM> is removed from the tissue of the patient by a tangential force to minimize or avoid trauma to the surrounding tissue of the patient. Specifically, the removal element <NUM> is engaged by the device removal tool <NUM> through the lumen <NUM>, as depicted in <FIG>. A tensile force is exerted on the removal element <NUM> by the device removal tool <NUM> such that the first end <NUM> of the pouch <NUM> is pulled into the lumen <NUM> toward the second end <NUM> of the pouch <NUM>, as depicted in <FIG>. As the device removal tool <NUM> is pulled further through the lumen <NUM> such that the first end <NUM> follows the device removal tool <NUM> through the lumen <NUM> towards the outside of the pouch <NUM>, the pouch <NUM> is atraumatically removed (e.g., peeled) from the surrounding tissue of the patient and is finally everted through the lumen <NUM>, as depicted in <FIG>. Once the therapeutic device <NUM> is removed from the pocket of tissue <NUM>, it can be withdrawn out of the patient by the device removal tool <NUM>.

Although the embodiments of the present disclosure describe a therapeutic device that is everted through a lumen, further embodiments in which the therapeutic device may be everted in various other manners are contemplated and are considered to be within the purview of this disclosure. The therapeutic devices may take any other shape or form, so long as at least one surface of the therapeutic device is free - i.e., not attached to tissue. For example, in some embodiments of the present disclosure, the therapeutic device is substantially planar or patch-like, without a lumen extending therethrough. In this embodiment, a single surface of the therapeutic device is attached to tissue via vascularization while an opposing surface prevents tissue attachment and thus, is free or unattached to tissue. In this embodiment, a removal element is attached to the free surface such that the attached side may be peeled away from the tissue upon application of a tensile force to the removal element.

In further embodiments, a method of removing a therapeutic device via a plurality of wrinkles incorporated in the therapeutic device is described herein. In some embodiments, the therapeutic device is implanted into, for example, a tissue of a patient. Once implanted, the therapeutic device is removed from the tissue by applying a tensile force to the removal element to minimize trauma to the surrounding tissue of the patient, such as is described in detail above. For instance, a second end of the therapeutic device may be engaged by a device removal tool and a tensile force is exerted on the second end to pull the second end in a direction away from a first end of the therapeutic device. As the second end is pulled in the direction of the tensile force, a first micro-wrinkle closest to the second end unfolds. As the device removal tool pulls the second end further away from the first end, each individual micro-wrinkle is unfolded one-by-one until the therapeutic device is atraumatically removed (e.g., peeled) from the surrounding tissue of the patient.

<FIG> depict an exemplary embodiment of a therapeutic device <NUM> extending from a first end <NUM> to a second end <NUM>. The therapeutic device <NUM> includes a first composite layer <NUM> and a second composite layer <NUM> sealed along a portion of their periphery <NUM>. A reservoir <NUM> is formed between the first and second composite layers <NUM>, <NUM>. The reservoir <NUM> is a contained space where cells are housed and is accessible by at least one port <NUM>, which is in fluid communication with the reservoir <NUM>. A periphery <NUM> of the therapeutic device <NUM> is sealed up to the location of the port <NUM>. The port <NUM> extends through the sealed periphery <NUM> and is in fluid communication with the reservoir <NUM>. In some embodiments, a lumen <NUM> extends through the therapeutic device <NUM>, as depicted in <FIG>.

The first and second composite layers <NUM>, <NUM> may be formed in the same manner, and have the same characteristics of, the first and second composite layers <NUM>, <NUM>, described herein. In some embodiments, that first composite layer <NUM> is a composite layer that includes a cell permeable layer <NUM> and a cell retentive layer <NUM>. In some embodiments, the second composite layer <NUM> includes a cell permeable layer <NUM> and a cell retentive layer <NUM>. The cell permeable layers <NUM>, <NUM> and the cell retentive layers <NUM>, <NUM> may be formed in the same manner, and have the same characteristics of, the cell permeable layers <NUM>, <NUM> and the cell retentive layers <NUM>, <NUM>, respectively. Specifically, as depicted in <FIG>, the cell permeable layers <NUM>, <NUM> are cell permeable layers which promote vascularization (i.e., form a capillary network <NUM>) therethrough up to the cell retentive layers <NUM>, <NUM> that are impervious to cell growth and vascularization. The cell retentive layers may be very thin so that the cells can still receive nutrients from the vascularization layers but vascularization stops at the interface of these two layers.

As depicted in <FIG>, in an exemplary embodiment, each of the first and second composite layers <NUM>, <NUM> includes a plurality of wrinkles <NUM>. "Wrinkles," as defined herein, form a topographic pattern with alternating peaks and valleys. Because the first and second composite layers <NUM>, <NUM> include these wrinkles <NUM>, the therapeutic device <NUM> is moveable between a relaxed state, depicted in <FIG>, in which the plurality of wrinkles extend in a direction generally perpendicular to a longitudinal axis of the therapeutic device <NUM> and an extended state in which the plurality of wrinkles are stretched between the first end <NUM> and the second end <NUM> so as to be generally parallel with the longitudinal axis of the therapeutic device <NUM>. A partially extended state is depicted in <FIG>. Specifically, as the second end <NUM> of the pouch <NUM> is pulled from the tissue bed, the tension applied to the therapeutic device <NUM> causes the wrinkles <NUM> to unfold, disconnecting the therapeutic device <NUM> from the tissue bed in which the therapeutic device <NUM> is implanted. This movement from the relaxed state to the extended states allows the removal of the therapeutic device <NUM> from a tissue bed of a patient with minimal trauma to the tissue in which the therapeutic device <NUM> is implanted. Furthermore, the plurality of wrinkles <NUM> may increase device effectiveness since the wrinkles increase effective surface area. The wrinkles <NUM>, in some embodiments, may be formed according to the teachings of <CIT>.

In some embodiments where first and second composite layers <NUM>, <NUM> are composite layers, only the outer layer comprises the plurality of wrinkles <NUM> overlying a non-wrinkled inner layer. In some embodiments, both the inner and outer layers comprise the plurality of wrinkles <NUM>.

The reservoir <NUM> is formed between the first composite layer <NUM> and the second composite layer <NUM> of the therapeutic device <NUM>. The reservoir <NUM> may take numerous configurations such as, for example, a planar or geometric shape (e.g., the general form of a rectangle, circle, square, semi-circle, semi-oval, etc.).

The reservoir <NUM> is configured to hold cells <NUM> within the therapeutic device <NUM> that is placed in a tissue bed of a patient, as depicted in <FIG>, to allow the cells <NUM> to provide biological therapy to the patient. In some embodiments, the cells <NUM> are introduced into the reservoir <NUM> of the therapeutic device <NUM> through one or more port(s) <NUM>. The port(s) <NUM>, similar to port(s) <NUM>, may be located anywhere along the therapeutic device <NUM>, so long as they are in fluid communication with the reservoir <NUM>. In some embodiments, the port(s) <NUM> extend through the sealed periphery between the first composite layer <NUM> and the second composite layer <NUM> of the sealed pouch <NUM> so that the cells <NUM> are introduced into the reservoir <NUM>.

In at least one embodiment where the therapeutic device <NUM> is used, the therapeutic device <NUM> is implanted within a pocket of tissue <NUM> of the patient, as depicted in <FIG>. The therapeutic device <NUM> may be implanted into the patient prior to or after the introduction of the cells <NUM> into the reservoir <NUM> of the therapeutic device <NUM>. When removal is deemed necessary or warranted, the therapeutic device <NUM> is removed from the tissue of a patient by application of a tensile force to minimize or reduce trauma to the tissue surrounding the device <NUM>. In some embodiments, the second end <NUM> of the therapeutic device <NUM> is engaged by the device removal tool <NUM>, as depicted in <FIG>. The device removal tool <NUM> may be, for example, a snare, hemostat, etc., which allows for removal of the therapeutic device <NUM> from an end closest to the user. A tensile force (T) is exerted on the second end <NUM> by the device removal tool <NUM> such that the second end <NUM> of the therapeutic device <NUM> is pulled in a direction away from the first end <NUM> so that a first micro-wrinkle closest to the second end <NUM> unfolds, as depicted in <FIG>. As the device removal tool <NUM> pulls the second end <NUM> further away from the first end <NUM>, the wrinkles <NUM> are unfolded until the therapeutic device <NUM> is atraumatically peeled from the surrounding tissue of the patient, as depicted in <FIG>.

In further embodiments, a method of removing a therapeutic device having a plurality of wrinkles via eversion is described. In some embodiments, the therapeutic device is implanted into, for example, a tissue of a patient. After the treatment is complete, or otherwise when removal is required, the therapeutic device may be removed from the tissue of the patient by a tangential force to minimize or avoid trauma to the tissue integrated into the therapeutic device. A removal element of the device is engaged, for example, by a device removal tool. A tensile force is exerted on the removal element by the device removal tool such that a first end of the therapeutic device is everted inwardly through itself toward a second end of the therapeutic device. As the first end is pulled in the direction of the tensile force, a first micro-wrinkle closest to the first end unfolds. As the device removal tool pulls the first end further toward the second end, the individual wrinkles are unfolded until the therapeutic device is atraumatically removed (e.g., peeled) from the surrounding tissue of the patient.

<NUM>-<NUM> depict an exemplary embodiment of a therapeutic device <NUM>. The therapeutic device <NUM> is substantially similar to therapeutic device <NUM> and includes a pouch <NUM> and a removal element <NUM> attached thereto. The pouch <NUM> extends from a first end <NUM> to a second end <NUM>. The pouch <NUM> includes a first composite layer <NUM> and a second composite layer <NUM>. A reservoir <NUM> is formed between the first and second composite layers <NUM>, <NUM>. The reservoir <NUM> is a contained space where cells are housed and is accessible by a port(s)<NUM>, which is in fluid communication with the reservoir <NUM>. A periphery <NUM> of the pouch <NUM> is sealed to the location of the port(s)<NUM>. In an exemplary embodiment, a hollow lumen <NUM> extends through the pouch <NUM>, as depicted in FIG. The removal element <NUM> of the therapeutic device <NUM> is attached to the first end <NUM> of the pouch <NUM> for atraumatic removal of the therapeutic device <NUM> by eversion.

Similar to therapeutic device <NUM>, a plurality of wrinkles <NUM> is incorporated into the therapeutic device <NUM>. In such an embodiment, each of the first and second composite layers <NUM>, <NUM> includes a plurality of wrinkles <NUM>. Because the first and second composite layers <NUM>, <NUM> include these wrinkles, the therapeutic device <NUM> is movable, in the body of the patient, between a relaxed state, in which the plurality of wrinkles extend in a direction generally perpendicular to a longitudinal axis L of the therapeutic device <NUM>, and an extended state, in which the plurality of wrinkles are stretched between the first end <NUM> and the second end <NUM> so as to be generally parallel with the longitudinal axis of the therapeutic device <NUM>.

The first and second composite layers <NUM>, <NUM> may be formed in the same manner as, and have the same characteristics of, the first and second composite layers <NUM>, <NUM>, described herein. In some embodiments, that first composite layer <NUM> is a composite layer that includes a cell permeable layer <NUM> and a cell retentive layer <NUM>. In some embodiments, the second composite layer <NUM> includes a cell permeable layer <NUM> and a cell retentive layer <NUM>. The cell permeable layers <NUM>, <NUM> and the cell retentive layers <NUM>, <NUM> may be formed in the same manner as, and have the same characteristics of, the cell permeable layers <NUM>, <NUM> and the cell retentive layers <NUM>, <NUM>, respectively.

The reservoir <NUM> is formed between the first composite layer <NUM> and the second composite layer <NUM> of the therapeutic device <NUM> and is a contained space configured to hold cells <NUM>. The reservoir <NUM> may be formed in the same manner as, and have the same characteristics of, the reservoir <NUM>, described herein.

In at least one embodiment where the therapeutic device <NUM> is used, the therapeutic device <NUM> is implanted within a pocket of tissue <NUM> of the patient, as depicted in FIG. The therapeutic device <NUM> may be implanted into the patient prior to or after the introduction of the cells <NUM>. When removal is deemed necessary or warranted, the therapeutic device <NUM> is removed from the tissue of the patient by application of a tangential force to minimize or avoid trauma to the surrounding tissue of the patient. Specifically, the removal element <NUM> is engaged by the device removal tool <NUM> through the lumen <NUM>, as depicted in FIG. A tensile force is exerted on the removal element <NUM> by the device removal tool <NUM> such that the first end <NUM> of the pouch <NUM> is pulled into the lumen <NUM> toward the second end <NUM> of the pouch <NUM>, as depicted in FIG. Concurrently, a first micro-wrinkle closest to the first end <NUM> unfolds, as depicted in FIG. As the device removal tool <NUM> is pulled further through the lumen <NUM> such that the first end <NUM> follows the device removal tool <NUM> through the lumen <NUM> towards the outside of the pouch <NUM>, each individual micro-wrinkle <NUM> is unfolded, from the first end <NUM> to the second end <NUM>, until the pouch <NUM> is atraumatically peeled from the surrounding tissue of the patient and is finally everted through the lumen <NUM>, depicted in FIG. Thus, the therapeutic device of this embodiment may allow for greater device efficacy due to the increased surface area of the plurality of wrinkles <NUM> while also employing an eversion removal technique to minimize trauma to the surrounding tissue.

In some embodiments, one or both composite layers of the described therapeutic devices is or includes a bio-absorbable material. The bio-absorbable material may be formed as a solid (molded, extruded, or crystals), a self-cohered web, a raised webbing, or a screen. In some embodiments, one or more layers of bio-absorbable material are attached to a non-bio-absorbable material having macroscopic porosity to allow for cell permeation (e.g., a cell permeable layer) to form a composite. In other embodiments, a non-bio-absorbable material having microscopic porosity to decrease or prevent cell permeation is releasably attached to the porous self-cohered web to permit atraumatic removal of the therapeutic device <NUM>, <NUM> from the patient days following implantation. Resorbing into the patient can promote favorable type <NUM> collagen deposition, neovascularization, and a reduction of infection. Furthermore, in some embodiments, the cell permeable layers may be made of a bioasorbable material that is tailorable to resorb at the rate of when explantation of the therapeutic device is needed, thus easing removal because the ingrowth of tissue into the therapeutic device would not be as significant.

Claim 1:
A cell encapsulation device (<NUM>) comprising:
a pouch (<NUM>) comprising:
opposed first and second ends (<NUM>, <NUM>);
first and second composite layers (<NUM>, <NUM>) extending between the opposed first and second ends (<NUM>, <NUM>), wherein the first composite layer includes (<NUM>):
a first cell permeable layer (<NUM>) extending between the opposed first and second ends (<NUM>, <NUM>); and
a first cell retentive layer (<NUM>) extending between the opposed first and second ends (<NUM>, <NUM>); and
wherein the second composite layer (<NUM>) includes:
a second cell permeable layer (<NUM>) extending between the opposed first and second ends (<NUM>, <NUM>); and
a second cell retentive layer (<NUM>) extending between the opposed first and second ends (<NUM>, <NUM>); and
a lumen (<NUM>) extending through the cell encapsulation device (<NUM>) from the first end (<NUM>) to the second end (<NUM>);
a reservoir (<NUM>) positioned between the first and second composite layers (<NUM>, <NUM>), the reservoir (<NUM>) contacting the first cell retentive layer (<NUM>);
at least one port (<NUM>) in fluid communication with the reservoir (<NUM>); and
a removal element (<NUM>) attached to or is integral with the first end (<NUM>) of the pouch (<NUM>) extending from the first end (<NUM>) into the lumen (<NUM>) to be accessible by a device removal tool such that during use a device removal tool inserted into the lumen (<NUM>) from the second end of the pouch (<NUM>) grasps the removal element (<NUM>) to exert a force on the removal element (<NUM>) through the lumen (<NUM>) to cause the device (<NUM>) to be removed by eversion.