# Patent

## Title
Method of treating an osteochondral defect

## Abstract

The present invention is directed to compositions having at least one neocartilage particle, juvenile cartilage particle or a combination thereof and a matrix, and methods and devices that include the compositions.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No. 12/861,404, filed Aug. 23, 2010, which is a continuation of U.S. patent application Ser. No. 11/010,779, filed Dec. 13, 2004, now U.S. Pat. No. 7,824,111, which claims priority from provisional application No. 60/528,865, filed Dec. 11, 2003, the entire disclosures of which are herein incorporated by reference.


BACKGROUND OF THE INVENTION
Injuries and damage to articular cartilage result in lesions in the cartilage that often lead to disability, pain and reduced or disturbed functionality. Historically there has been limited success in the repair of these injuries and lesions, (i.e., characterized by a repair that re-establishes a structurally and functionally competent articular cartilage tissue of a lasting nature). Many injuries and defects to articular cartilage penetrate the bone and bone-marrow spaces as well (i.e., an osteochandral defect).
Articular cartilage tissue has a tough and elastic character; it covers the ends of bones in joints and enables the bones to move smoothly over one another. Numerous diseases, including osteoarthritis, and traumatic injuries from activities and accidents cause damage to articular cartilage.
Articular cartilage lacks a direct blood supply, is aneural, alymphatic, and contains a single cell type, the chondrocyte. Its lack of vascularization, high matrix to-cell ratio and lack of a local source of undifferentiated cell reserves results in a limited capacity to regenerate following injury or degenerative loss. Repair of damaged or diseased mature articular cartilage historically has been difficult because of its very limited ability to self-repair. Adult human articular cartilage usually does not self-repair or only partially heals under normal biological conditions.
In the past, repair interventions based on the use of adult human tissue or isolated chondrocyte autografts or allografts have not provided completely satisfactory results, from the standpoint of a restoration of the architecture of the articulating surface.
Grafting of pure articular cartilage alone has shown little or no success, nor has the implantation of isolated cartilage flakes after traumatic dissociation or ablation without a bony support, as cartilage does not adhere to bony surfaces nor is bone able to facilitate cartilage fixation.
In vitro culture of chondrocytes under controlled conditions can give rise to normal articular cartilage tissue growth. Adkisson, U.S. Pat. Nos. 6,235,316 and 6,645,764. However, normal adult chondrocytes generally have lost their potential to reproduce and generate new cartilage in vivo, although they are responsible for 15 maintaining tissue homeostasis. Accordingly, there exists a need for improved compositions and methods for repairing articular cartilage.
BRIEF SUMMARY OF THE INVENTION
One aspect of the present invention is directed to compositions including a cartilage or a neocartilage construct of juvenile cartilage particles and biocompatible chondro-conductive/inductive matrix. Some embodiments may further include an osteo-conductive matrix. The cartilage may be distributed throughout substantially all of the biocompatible chondro-conductive matrix or just a portion of the matrix, the portion may range from 90 to 10%. In some embodiments the surface-to-volume ratio of the cartilage particles is greater than 1. In any embodiment the biocompatible chondro-conductive/inductive matrix may be fibrinogen, fibrinogen/thrombin, albumin, in-situ forming poly(ethylene glycol) (PEG) hydrogel, fibrin/hyaluronate, fibrin/collagen/hyaluronate, PEG/hyaluronate, PEG/collagen, other plasma and protein-based adhesives and sealants, other natural adhesives and sealants and any combination thereof. In any embodiment the composition may further comprise an osteo-conductive matrix. The osteo-conductive matrix may be fibrinogen, fibrinogen/thrombin, fibrin/tri-calcium phosphate, fibrin/collagen/tri-calcium phosphate, fibrin/hyaluronate/tri-calcium phosphate, in-situ forming PEG hydrogel sealants, PEG/tri-calcium phosphate, PEG/collagen, demineralized bone matrix, and any combination thereof. In any embodiment the composition may include an associated matrix containing II collagen I, polylactic acid (PLA) and polyglycolic acid (PGA).
In any embodiment the composition may include other cartilage tissues, such as costal cartilage, nasal cartilage, trachea cartilage, sternum cartilage and any other cartilage tissue that contains Collagen II and not Collagen I and III.
Another aspect of the invention may include a composition containing neocartilage or juvenile cartilage particles from a non-autologous source.
Another aspect of the invention is directed toward or includes methods of using the inventive compositions for inducing articular cartilage (i.e., a chondral defect) formation, repairing articular cartilage or repairing articular cartilage together with filling a bone defect in vertebrates (i.e., an osteochondral defect). The methods include disposing the inventive compositions in a site where regeneration, augmentation, the induction of articular cartilage formation, the repairing of articular cartilage or the repairing of articular cartilage and also filling a bone defect, is desired.
Another aspect of the invention includes a device including any of the compositions of the invention and the device may also be used in a method of articular cartilage repair by disposing the device in a defect in need of repair.
Yet another aspect of the invention includes a method of preparing any of the compositions of the invention, scoring a surface of juvenile cartilage or neocartilage; separating at least a portion of the scored cartilage from underlying bone; and adding a preservative to the separated cartilage.
Another aspect of the invention includes a kit for repairing cartilage including any of the compositions of the invention, a pouch having a hollow interior; a sterile container positioned in the hollow interior having a receptacle therein; and one or more particles of juvenile cartilage and/or neocartilage positioned in the receptacle of the container.
These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims and accompanying figures where:



BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS AND FIGURES
FIG. 1 shows an embodiment of the invention wherein cartilage particles are distributed throughout substantially all of the biocompatible chondro-conductive/inductive matrix.
FIG. 2 shows an embodiment of the invention wherein cartilage particles are distributed throughout approximately 75% or less of the biocompatible chondroconductive/inductive matrix.
FIG. 3 shows an embodiment of the invention wherein cartilage particles are distributed throughout substantially all of the biocompatible chondro-conductive/inductive matrix and further comprises a particulate osteo-conductive matrix.
FIG. 4 shows juvenile cartilage particles encapsulated within a hyaluronate hydrogel.
FIG. 5 shows the morphologic appearance of human juvenile cartilage particles, pre-cast in a fibrin matrix, after 60 days of laboratory culture.
FIG. 6 shows a repaired medial femoral condyle (right side of photograph) of a Spanish goat, 6 weeks after implantation of human juvenile cartilage particles with a fibrin matrix and live periosteal flap.
FIG. 7 shows a 1 mm thick section through the defect site represented in FIG. 6.
FIG. 8 shows viable human juvenile cartilage implanted into a goat femoral condyle 6 weeks after surgery.
FIG. 9 shows the morphologic appearance of human juvenile cartilage particles implanted into a goat femoral condyle 6 weeks after surgery.



DETAILED DESCRIPTION OF THE INVENTION
The term “juvenile cartilage” refers to a chondrocyte cell, cells, cartilage tissue, or progeny or derivatives thereof, that are committed to become cartilage, or progenitor cells which are capable of undergoing proliferation growth, differentiation and maturation into chondrocytes and formation of cartilaginous tissue. In general, such chondrocytes are most readily found in tissue from individuals who encompass allograft, autograft and xenograft sources. In humans, preferably chondrocytes are from those less than fifteen years of age, and more preferably, less than two years of age. Typically, immature or juvenile chondrocytes express an enhanced ability to synthesize and organize a hyaline cartilage extra-cellular matrix. This activity usually is highest in cells freshly isolated from donor tissue and decays during subsequent manipulation such as passage and expansion.
The term “neocartilage” refers to cartilage characterized by one or more of the following attributes: containing membrane phospholipids enriched in Mead acid, containing membrane phospholipids depleted in linoleic or arachidonic acid, being substantially free of endothelial, bone and/or synovial cells, having a sulfated glycosaminoglycan S-GAG content of at least 400 mg/mg, positive for type II collagen expression, being substantially free of type I, III and X collagen, containing a matrix substantially free of biglycan, having multiple layers of cells randomly arranged, rather than separated into distinct zones of chondrocyte maturation, being enriched in high molecular weight aggrecan, being produced in vitro and essentially free of non-cartilage material, or being characterized by having multiple layers of cells surrounded by a substantially continuous insoluble glycosaminoglycan and collagen-enriched hyaline extracellular matrix.
The term “biocompatible” refers to materials which, when incorporated into the invention, have acceptable toxicity, acceptable foreign body reactions in the living body, and acceptable affinity with living tissues.
The term “chondro-inductive” refers to the ability of a material to induce the proliferation, growth differentiation and/or other maturation of chondrocytes or chondroprogenitor cells and/or proliferation, growth differentiation and/or maturation of chondrocytes or chondroprogenitor cells or production of articular cartilage from neocartilage progenitor cells, chondrocytes or cartilage. A chondro-inductive material may act directly as a growth factor which interacts with precursor cells to induce chondrocyte proliferation, growth differentiation and/or maturation, or the material may act indirectly by inducing the production of other chondro-inductive factors, such as growth factors. This induction may optionally include without limitation signaling, modulating, and transforming molecules.
The term “chondro-conductive” refers to materials which provide an environment for proliferation, differentiation, growth, ingrowth and/or orientation of cartilage tissue, chondrocyte cells or chondroprogenitor cells from surrounding tissues.
The term “chondro-inductive/conductive” refers to the characteristic of being both chondro-inductive and chondro-conductive.
The term “matrix” refers to substance(s) which adhered to or partially embedded within which something is contained.
The term “osteo-conductive” refers to materials which provide an environment for proliferation, differentiation, growth, ingrowth and/or orientation of osteogenic cells.
The term “flap” refers to an autologous or allogenic membrane of live cells, natural or synthetic material that can be vital or devitalized. The flap contains the matrix with cartilage particles that can be attached to natural cartilage or underlying bone in vivo by sutures or sutureless attachment such as chemical tissue welding or gluing, or by physical attachment devices such as tacks or staples.
The compositions and methods as described herein comprise useful repair of damaged or diseased articular cartilage. The compositions and methods include a cartilage matrix or particles and a biocompatible chondro-conductive/inductive matrix.
In another aspect of the invention a device as described herein may be disposed into a site of cartilage repair, regeneration or augmentation.
In another aspect of the invention, the compositions further comprise a particulate osteo-conductive matrix.
In other embodiments the cartilage matrix comprises a cartilage growth-enhancing material selected from the group consisting of at least one juvenile cartilage particle, at least one neocartilage particle, a combination thereof, and any of the above together with an associated matrix.
The compositions may be used according to the methods of the invention, for implanting or transplanting or otherwise disposing a reparative construct into a site in need of articular cartilage repair, regeneration or growth.
In another aspect of the invention a device may be formed from the inventive compositions and the device may be disposed in a site in need of articular cartilage repair.
In some embodiments the compositions further comprise a particulate osteoconductive matrix.
The biocompatible chondro-conductive/inductive matrix of the invention comprises any appropriate compound or combination of compounds that is inductive or conductive for the formation or repair of articular cartilage in the inventive compositions and methods.
The chondro-conductive/inductive matrix may comprise fibrinogen. The fibrinogen may be from any suitable source. For example, one skilled in the art will recognize that fibrinogen may be derived from blood bank products—either heterologous (pooled or single-donor) or autologous cryoprecipitate or fresh frozen plasma. Fibrinogen can also be derived from autologous fresh or platelet-rich plasma, obtained using cell-saver or other techniques. U.S. Pat. No. 5,834,420 also discloses a method for obtaining fibrinogen.
In other embodiments the biocompatible chondro-conductive/inductive matrix comprises thrombin. The thrombin may be from any suitable source. One skilled in the art will recognize that thrombin can be isolated by well known means or purchased commercially. See U.S. Pat. No. 4,965,203, and Berliner, J L, Thrombin: Structure and Function (Ed) Plenum Pub Corp; (1992) for exemplary methods of isolation and/or purification.
In any embodiment the biocompatible chondro-conductive/inductive matrix may comprise a combination of fibrinogen and thrombin. The chondro-conductive/inductive matrix may contain equal proportions of fibrinogen and thrombin or more of either fibrinogen than thrombin or more thrombin than fibrinogen. When used in combination the two may be in any proportion, ranging from one part of either compared to the amount of the other up to equal proportions of each of the two.
Regardless of whether the fibrinogen or the thrombin are mixed with the neocartilage, juvenile cartilage or are separate components of the biocompatible chondro-conductive/inductive matrix, when practicing certain embodiments of the invention the fibrinogen and thrombin components preferably are kept separate from each other prior to the time of use. The fibrinogen and the thrombin are then brought into contact with each other at the time of use. A common type of applicator that may be used for this purpose consists of a double syringe, joined by a Y-connector where the components mix as they emerge. This type of applicator, used with a blunt cannula, is useful for combining the thrombin and the fibrinogen and also useful in the methods of the invention for disposing or transplanting the inventive compositions to a site wherein articular cartilage repair is desired. In cases where the articular cartilage repair site is open for repair, the fibrinogen and/or thrombin can also be used with a spray attachment to cover surfaces; or the fibrinogen and/or thrombin may be applied to an absorbable carrier or dressing, such as a cellulose sponge, collagen fleece, vital or devitalized periosteum or any other suitable means.
In various embodiments the chondro-conductive/inductive matrix may comprise one or more of fibrinogen, thrombin, fibrinogen/thrombin (Tisseel or Crosseal), albumin, in-situ forming poly (ethylene glycol) (PEG) hydrogel, fibrin, hyaluronate, fibrin/hyaluronate, collagen hyaluronate, fibrin/collagen/hyaluronate, PEG/hyaluronate, PEG/collagen, PEG base sealants (CoSeal), or other plasma and protein-based adhesives and/or sealants, other natural adhesives and/or sealants and combinations thereof, that are biocompatible with regard to the articular cartilage repair or replacement and are inductive or conductive for the cartilage matrix or cartilage growth-enhancing material in the repair or replacement of articular cartilage.
The biocompatible chondro-conductive/inductive matrix, may in some embodiments optionally function to facilitate anchoring and/or fixation of the composition in the methods of the invention to repair the desired articular cartilage.
The invented compositions may also include materials which are not yet known, but which provide characteristics relating to these components which are similar to the materials described herein.
The cartilage tissue in certain embodiment of the inventive composition also may comprise neocartilage or juvenile cartilage or a combination of neocartilage or juvenile cartilage. The neocartilage and juvenile cartilage may be in any proportion to each other, ranging from one cell or part of either compared to the other up to equal proportions of each of the two. For example, the cartilage matrix or cartilage growth-enhancing material may contain equal proportions of neocartilage and juvenile cartilage or more of either neocartilage than juvenile cartilage or more juvenile cartilage than neocartilage. In some embodiments the compositions of the invention further comprise a particulate osteo-conductive matrix. The neocartilage or juvenile cartilage is in the form of particles in the cartilage matrix or cartilage growth-enhancing material. The particles increase the surface to volume ratio in the cartilage matrix or cartilage growth-enhancing material, which allows for improved integration and metabolite and growth factor exchange, which advantageously results in enhanced viability and shelf life for the compositions. The neocartilage and juvenile cartilage particles may vary in size ranges [from) 1 to 27 mm3. Thus, the neocartilage and juvenile cartilage particles placed in cartilage matrix or cartilage growth-enhancing material also may vary in size from single cells with associated matrix to 100 mm3 in size depending on application or defect type. For a somewhat typical defect of 2 cm, at least 1×106 to 2×106 cells would be disposed, preferably 2×106 to 4×106, and most preferably 10×106 to 20×106. The amount of cells used may vary depending on the specific circumstances of a defect in need of repair and the goals of the patient. For example, one skilled in the art would recognize that on average, adult tissue has about a 5 to 10% cell mass per gram of tissue. This equates to about a 7% fill. However, some cell death will likely occur during maturation so a higher initial cell count is typically preferable.
In terms of providing economic ratios of tissue to percentage fill of defects, to maximize tissue use, approximately 300 mg of tissue would provide for about a 50% defect fill, although less, approximately 200 mg, for a 30% defect fill, and most preferably, for a 10% defect fill, 60 mg would be utilized.
The matrix portion of the cartilage matrix or cartilage growth-enhancing material may comprise thrombin, fibrinogen, media or fibrinogen in combination with media or thrombin in combination with media. Any suitable media may be used for the media component. Examples of suitable media include, but are not limited to a conditioned growth medium adapted for use in growing cartilage cell cultures which contains heparin-binding growth factors, at least one of which is a cartilage-derived morphogenetic protein (Chang et al., J. Biol Chem 269: 28227-28234), other pre-conditioned medias, Dulbecco's modified Eagle's medium (DMEM), Minimum Essential Medium and RPMI (Roswell Park Memorial Institute) medium. The culture medium may also comprise ascorbate, and/or exogenous autocrine growth factors.
The juvenile cartilage in the invention may be from any suitable source. The juvenile cartilage or chondrocytes used in the composition may be harvested from donor tissue and prepared by dividing or mincing the donor cartilage into small pieces or particles. The juvenile cartilage particles may comprise juvenile cells or tissue, which may be intact, minced or disrupted, such as by homogenizing the tissue. Examples of sources of donor cartilage include autologous, allogenic or xenogenic sources. In the case of autologous grafts, cartilage is harvested from cartilaginous tissue of the patient's own body. Typical sources for autologous donor cartilage include the articular joint surfaces, intercostals cartilage, and cartilage from the ear or nasal septum. In the case of allografts, the cartilage may be taken from any appropriate non-identical donor, for example from a cadaveric source, other individuals or a transgenic source or similar appropriate source.
In any embodiment of the invention the cartilage matrix or cartilage growth-enhancing material may comprise juvenile cartilage (without neocartilage) in any suitable tissue culture media. The juvenile cartilage may also comprise juvenile cartilage tissue in a matrix of thrombin or juvenile cartilage in a matrix of fibrinogen.
In any embodiment that includes neocartilage, the cartilage matrix or cartilage growth-enhancing material may comprise neocartilage cells in any suitable tissue culture media. The neocartilage matrix or cartilage growth-enhancing material may also comprise neocartilage in a thrombin matrix or neocartilage in a fibrinogen matrix.
In embodiments having neocartilage, the neocartilage may be from any suitable source. The neocartilage particles may comprise neocartilage cells or tissue, which may be intact, minced or disrupted, such as by homogenizing the tissue. The neocartilage may be either autologous or allogenic. Examples of suitable sources include commercially available sources, such as Carticel® (Genzyme Biosurgery, Cambridge, Mass.), embryonic sources, tissue culture sources or any other suitable source. For example a cell culture may be produced to grow neocartilage by isolating immature chondrocytes, e.g., fetal, neonatal, and preadolescent chondrocytes from donor articular cartilage. The neocartilage of the inventive cartilage matrix or cartilage growth-enhancing material may be obtained by culturing chondrocytes under suitable culture conditions known in the art, such as growing the cell culture at 37 degrees C. in a humidified atmosphere with the addition of 2-10% carbon dioxide, preferably 5%. Chondrocytes may be isolated by methods known in the art such as by sequential enzyme digestion techniques. The isolated chondrocytes may then be seeded directly on a tissue culture vessel in any suitable media. Also see, for examples of other sources, U.S. Pat. No. 5,326,357 which describes methods to produce a continuous cartilaginous tissue and U.S. Pat. No. 6,235,316 which discloses neocartilage compositions and uses, which are incorporated by reference, herein in their entirety.
The juvenile or neo cartilage tissue for the cartilage matrix or cartilage growth-enhancing material can be mammalian or avian replacement tissue, most preferably from the same species as the recipient, for example human donor tissue for human replacement and equine tissue for equine use. Furthermore, mammalian replacement tissue can be produced using chondrocytes from transgenic animals which may have been genetically engineered to prevent immune-mediated xenograft rejection.
In embodiments where the matrix portion of the cartilage matrix or cartilage growth-enhancing material comprises tissue culture media, without fibrinogen or thrombin, then the biocompatible chondro-conductive/inductive matrix preferably comprises fibrinogen and thrombin.
In embodiments where the matrix portion of the cartilage matrix or cartilage growth-enhancing material comprises media and fibrinogen, then the biocompatible chondro-conductive/inductive matrix preferably comprises thrombin.
In embodiments where the matrix portion of the cartilage matrix or cartilage growth-enhancing material comprises media and thrombin, then the biocompatible chondro-conductive/inductive matrix preferably comprises fibrinogen.
In different embodiments various combinations of the cartilage matrix or cartilage growth-enhancing material and the biocompatible chondro-conductive/inductive matrix are possible. By way of non-limiting example, an embodied composition may comprise juvenile cartilage and thrombin in the cartilage matrix with the biocompatible chondro-conductive/inductive matrix comprising media and fibrinogen.
In another embodiment the cartilage matrix or cartilage growth-enhancing material may comprise neocartilage and thrombin with the biocompatible chondro-conductive/inductive matrix comprising media and fibrinogen.
In another embodiment the cartilage matrix or cartilage growth-enhancing material may comprise a combination of juvenile and neocartilage in thrombin with the biocompatible chondro-conductive/inductive matrix comprising media and fibrinogen.
In any embodiment the compositions may further comprise an osteo-conductive matrix. The osteo-conductive matrix comprises bone particles. The bone particles may be from any suitable source. The osteo-conductive matrix may include but not be limited to fibrinogen/thrombin (Tisseel, Crosseal), fibrin/tri-calcium phosphate, fibrin/collagen/tri-calcium phosphate, fibrin/hyaluronate/tri-calcium phosphate PEG base sealants (CoSeal), PEG/tri-calcium phosphate, PEG/collagen (FibroGen) and any of the above components mixed with demineralized bone matrix. The osteo-conductive matrix may be purchased from commercial sources, such as the demineralized bone matrix compositions Grafton® (Osteotech, Eatontown, N.J.). Examples of other sources suitable for the osteo-conductive matrix include those disclosed in U.S. Pat. No. 5,356,629, U.S. Pat. No. 6,437,018 and U.S. Pat. No. 6,327,257. Suitable compositions may comprise demineralized bone, demineralized bone matrix, nondecalcified bone, cancellous bone or combinations of the same and a gel material. The osteo-conductive matrix may also comprise a porous solid, semisolid, paste or gel material including materials such as gelatin, hyaluronic acid, collagen, amylopectin, demineralized bone matrix, and/or calcium carbonate fibrinogen/thrombin, fibrin/tri-calcium phosphate, fibrin/collagen/tri-calcium phosphate, fibrin/hyaluronate/tri-calcium phosphate, in-situ forming PEG hydrogel sealants in-situ forming PEG hydrogel sealants, PEG/tri-calcium phosphate, PEG/collagen, demineralized bone matrix, and any combination thereof.
Osteoconductive materials are generally porous materials and are able to provide latticework structures such as the structure of cancellous bone or similar to cancellous bone. Such materials may generally facilitate blood-vessel incursion and new bone formation into a defined passive trellis-like support structure, as well as potentially supporting the attachment of new osteoblasts and osteoprogenitor cells. Osteoconductive materials may provide an interconnected structure through which new cells can migrate and new vessels can form.
Examples of materials suitable for the osteoconductive matrix include those disclosed in U.S. Pat. No. 5,356,629 which discloses a composition of polymethylacrylate biocompatible particles dispersed in a matrix of cellulose ether, collagen or hyaluronic acid and U.S. Pat. No. 6,437,018 which includes a composition of demineralized bone matrix (DBM) in an aqueous carrier that is sodium hyaluronate in a phosphate buffered aqueous solution. U.S. Pat. No. 6,327,257 discloses compositions with demineralized bone, nondecalcified bone, cancellous bone and a gel material. There are also compositions that are available commercially, including demineralized bone matrix compositions such as Grafton® (Osteotech, Eatontown, N.J.). These compositions typically comprise a porous solid, semisolid, paste or gel material including materials such as gelatin, hyaluronic acid, collagen, amylopectin, demineralized bone matrix, and/or calcium carbonate, to create an osteoconductive environment.
In some embodiments the composition optionally further comprises other components or compounds to address the needs of a particular articular cartilage injury or circumstance or a specific patient's individual needs. By way of non-limiting example the biocompatible chondro-conductive/inductive matrix may in some instances comprise albumin, in-situ forming PEG hydrogel, fibrin/hyaluronate, fibrin/collagen/hyaluronate, PEG/hyaluronate, PEG/collagen, other plasma and protein-based adhesives and sealants, other natural adhesives and sealants and any combination of these.
In any embodiment the cartilage matrix may be distributed throughout substantially all of the biocompatible chondro-conductive/inductive matrix, as shown in FIG. 1. Alternatively the cartilage matrix may be distributed throughout a portion of the biocompatible chondro-conductive/inductive matrix, as shown in FIG. 2. The cartilage matrix may be distributed throughout 90% or less of the biocompatible chondro-conductive/inductive matrix. The cartilage matrix may also be distributed throughout 80% or less of the biocompatible chondro-conductive/inductive matrix. The cartilage matrix may also be distributed throughout 70% or less of the biocompatible chondro-conductive/inductive matrix. The cartilage matrix may also be distributed throughout 60% or less of the biocompatible chondroconductive/inductive matrix. The cartilage matrix may also be distributed throughout 50% or less of the biocompatible chondro-conductive/inductive matrix. The cartilage matrix may also be distributed throughout 40% or less of the biocompatible chondroconductive/inductive matrix. The cartilage matrix may also be distributed throughout 30% or less of the biocompatible chondro-conductive/inductive matrix. The cartilage matrix may also be distributed throughout 20% or less of the biocompatible chondro-conductive/inductive matrix. The cartilage matrix may also be distributed throughout 10% or less of the biocompatible chondro-conductive/inductive matrix.
Similarly, in embodiments where the compositions and methods further comprise an osteo-conductive matrix, the osteo-conductive matrix may be distributed throughout substantially all of the composition. Alternatively the osteo-conductive matrix may be distributed throughout a portion of the composition. It may be desirable in some embodiments to have the osteo-conductive matrix disposed to contact bone in a defect that has involvement of both bone and articular cartilage, as shown in FIG. 3. The osteo-conductive matrix may be distributed throughout 90% or less of the composition. The osteo-conductive matrix may also be distributed throughout 80% or less of the composition. The osteo-conductive matrix may also be distributed throughout 70% or less of the composition. The osteo-conductive matrix may also be distributed throughout 60% or less of the composition. The osteoconductive matrix may also be distributed throughout 50% or less of the composition. The osteo-conductive matrix may also be distributed throughout 40% or less of the composition. The osteo-conductive matrix may also be distributed throughout 30% or less of the composition. The osteo-conductive matrix may also be distributed throughout 20% or less of the composition. The osteo-conductive matrix may also be distributed throughout 10% or less of the composition.
In one embodiment a method of use comprises disposing a cartilage matrix of neocartilage or juvenile cartilage, or a combination thereof and a biocompatible chondro-conductive/inductive matrix in any location where repair or replacement of articular cartilage is desired.
In one embodiment a method of use comprises disposing a cartilage matrix of neocartilage or juvenile cartilage, or a combination thereof and a biocompatible chondro-conductive/inductive matrix and an osteo conductive matrix in any location where repair or replacement of articular cartilage is desired. Compositions and methods of the invention comprising the osteo conductive matrix are useful for repair of replacement of articular cartilage at a site that also includes a bone defect.
In other embodiments a method of use comprises disposing any embodiment of the compositions of the invention into a defect and overlaying the composition with a retainer. The retainer may be of any suitable size and material that functions to maintain the particle in the site where the particle(s) is disposed. The retainer may be for example a flap, plug, disc, sheet or patch. In one embodiment the retainer comprises a flap. The flap is made up of either live cells, such as periosteum cells, other natural tissue membrane or synthetic membrane. The periosteal flap may be vital or devitalized and may be an autologous or an allograft.
Any of the embodiments of the inventive compositions may be used in any of the embodiments of the methods of the invention. The compositions may be extruded or otherwise disposed into the targeted site or configured into a device for transplanting into a desired site (FIG. 1). Typically a multi-unit dispensing device such as a double or triple syringe, joined by a Y-connector, or similar converging connector from the dispensing unit may be used where the components mix as they emerge from a blunt cannula or catheter or other similar device. Any embodiment of the compositions may be delivered to the defect site through an arthroscopic portal from a mixing mechanism that automatically meters the components in the correct ratio, into the desired site for articular cartilage repair or replacement.
Delivery of the compositions may be in a variety of forms and combinations; by way of non-limiting example the cartilage matrix may be in media and mixed with biocompatible chondro-conductive/inductive matrix comprising fibrinogen and thrombin just prior to use as a 3 part mixture. Alternatively, the cartilage matrix may include thrombin and be combined with a fibrinogen biocompatible chondro-conductive/inductive matrix at the time of use, as a 2 part mixture. In another alternative, the cartilage matrix may include fibrinogen and be combined with a biocompatible chondro-conductive/inductive matrix comprising thrombin at the time of use, as a 2 part mixture. By changing the particles included in the matrix, for example the juvenile cartilage pieces, in vitro-grown neocartilage and the components that comprise the chondro-inductive matrix and/or the osteo-conductive matrix, the nature of the repair graft can be varied from partial thickness through full thickness into osteochondral defects, as desired and/or in response the to the specific site where repair or replacement is desired. Another alternative for delivery is that various combinations of the cartilage matrix and the biocompatible chondroconductive/inductive matrix may be preformed and implanted as a single construct. By way of non-limiting example, an embodied composition may comprise juvenile cartilage pre-cast in a biocompatible chondro-conductive/inductive matrix comprising fibrin.
The juvenile neocartilage replacement tissue or pre-cast construct made up of the juvenile cartilage, a chondro conductive/inductive matrix and/or an osteoconductive matrix can also be attached to natural cartilage or underlying bone in vivo by sutures or sutureless attachment such as chemical tissue welding or gluing, or by physical attachment devices such as tacks or staples. The neocartilage may be grown to various size specifications to facilitate implantation.
Any of the compositions may be configured to form a device of the present invention and the device may then be implanted, inserted or otherwise suitably disposed in a site where repair or replacement of articular cartilage is desired. For example any embodiment of the compositions may be extruded or delivered into a form or mold to produce a specific shape or configuration of device and the produced device may then be appropriately implanted or otherwise disposed in the site where replacement or repair of articular cartilage is desired.
In all cases, the compositions and devices of the invention will have a period of plasticity during which they can be implanted and/or molded to the defect being repaired. These methods of delivery advantageously make implantation of the repair articular cartilage possible in a single arthroscopic procedure, if desired. Once implanted, the cartilage fragments coalesce and replace the matrix with hyaline cartilage tissue. This method can also be extended to neocartilage grown in vitro with the advantage that some expansion of chondrocytes/neocartilage can be done, generating more repair tissue from a single donation of juvenile cartilage. Juvenile chondrocytes and/or juvenile cartilage/neocartilage can be combined with the biocompatible matrix using a uniform distribution as illustrated in FIG. 1 or a nonuniform distribution to increase the cartilage/chondrocyte density as illustrated in FIG. 2 and FIG. 8, where the cartilage is at a higher density near the bottom of the defect.
Similarly, different components can be mixed with the biocompatible matrix to fill chondral and osteochondral defects. FIG. 3 illustrates a potential usage wherein the bone defect is filled with an osteo-conductive matrix up to the tide mark, above which the chondral defect is filled with juvenile chondrocytes and/or juvenile cartilage/neocartilage matrix combined with the biocompatible matrix.
The cartilage may be harvested from cartilage donors such as juvenile animals. For example, the donors may be prepubescent humans aged between about 20 weeks and about 13 years. The cartilage may be harvested from a variety of cartilage sites, including facing surfaces of bones positioned at articulating joints. Among particularly desirable harvest sites are Nmorall condyles, tibial plateaus and interior surfaces of patella. To harvest the cartilage, the harvest sites are exposed. The surface of a harvest site is scored with a blade such as a #10 scalpel having a ceramic coated edge (e.g., an IonFusion scalpel blade available from IonFusion Surgical, a division of Molecular Metallurgy, Inc. of El Cajon, Calif.) Although the site may be scored in other patterns without departing from the scope of the present invention, in one embodiment the site is scored in a square grid pattern having sides measuring about one millimeter. Further, although the site may be scored to other depths without departing from the scope of the present invention, in one embodiment the site is scored to a depth of between about one millimeter and about three millimeters or more. Once the site is scored, at least a portion of the scored cartilage is separated from underlying bone, such as by shaving the scored surface with the aforementioned scalpel. As will be appreciated by those skilled in the art, separating the cartilage in this fashion results in small generally cube-shaped particles of cartilage having sides of about one millimeter. Tissue other than cartilage, such as vascularized bone and tendons, generally should be avoided when separating the cartilage from the bone.
The separated particles are collected in a container such as a conical tube. The particles may be stored in or rinsed with a saline solution such as a 0.9% saline solution. After rinsing or storage, the saline solution may be removed from the particles by aspiration and another preservative may be added to the particles. For example, a storage solution comprising hydroxyethyl starch (50 g/L) m lactobionic acid (35.8 g/L), adenosine (1.34 gL), NaOH (5M) (5 mUL), KH2PO4 (3.4 g/L), MgSO4 (0.6 g/L), glutathione (0.92 g/L), raffinose (17.8 g/L), and KOH (5M) (pH to 7.4) may be added to the particles.
A kit for repairing cartilage may be formed using the particles. Generally, the kit includes an outer bag or pouch having a hollow interior, a sterile container positioned in the hollow interior, and cartilage particles positioned in a receptacle of the container. Although the outer pouch may have other configurations without departing from the scope of the present invention, in one embodiment the pouch is formed from two sheets, each of which has a central portion surrounded by a margin. The sheets are separably joined to one another at their margins. One such pouch is available from Amcor Flexibles Healthcare of Ann Arbor, Mich., and is identified as an RLP-041 HS pouch made from a 48 ga PET/10 lb LDPE/2 mil peelable film (LFM-101). The pouch is about 4×6 inches and has 15 degree chevron configuration with thumb notch. In one embodiment, the container includes a tray having a teardrop-shaped central cup or receptacle and a lip or flange surrounding the receptacle. One such container is available from Prent Corporation of Janesville, Wis., and is formed from a laminate comprising a Glidex sheet sandwiched between PETG sheets having an overall thickness of about 0.020 inch. A removable cover is attached to the lip of the tray for sealing the receptacle to retain the particles in the receptacle. One such cover is available from Tolas Health Care Packaging of Feasterville, Pa., and is known as a TPC-0777A peelable lamination for Oevicel packaging. Although the cover may have other dimensions without departing from the scope of the present invention, in one embodiment the cover has a thickness of about 3.95 mils and is about 1.57×3.15 inches.
In one embodiment, excess liquid is removed from the particles by aspiration and a 50 mg scoop is used to measure a desired quantity of particles into a sterile tray, a desired measure of preservative solution (e.g., 2.5 mL) is added to the tray and the cover is sealed against the rim of the tray to close the container. The container is loaded into a pouch and the pouch is sealed for storage and transport. Once ready for use, the pouch is pealed open and the container is deposited in a sterile environment. The non-sterile pouch is disposed and the container is opened by peeling back the cover to expose the particles of cartilage.
EXAMPLES
Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following specific examples are offered by way of illustration only and not by way of limiting the remaining disclosure.
Example 1
Juvenile Human Articular Cartilage (JHAC) in a Hyaluronate Matrix
In certain embodiments of the composition as described herein particulate JHAC was embedded within a hyaluronate hydrogel and evaluated for their viscosity and their ability to adhere within a defect. Hyaluronate forms a viscous gel that can hold the cartilage particles within a defect during implantation. Concentrations of hyaluronate ranging from 5 mg/ml to 100 mg/ml were tested in this example. In the mixture illustrated by FIG. 4, JHAC was embedded in a gel containing 50 mg of hyaluronate dissolved in 1 ml of phosphate buffered saline. Although suitable for a matrix, hyaluronate alone lacked cross-linking within the gel. Therefore, in one preferred composition, a component such as fibrin is included to retard or prevent dissolution of the chondro-conductive matrix.
Example 2
In Vitro JHAC Re-Integration
When juvenile tissue is maintained in the laboratory embedded within a fibrin matrix, the tissue has the ability to re-integrate. In this experiment, JHAC was minced and cast in human fibrinogen within a cylindrical mold and then cultured for 60 days in a standard cell culture using a proprietary serum-free medium, developed at ISTO Technologies, Inc. The tissue composite was then fixed and histological slides were prepared and stained with Safranin-O which stains red in the presence of sulfated glycosaminoglycan (S-GAG). Safranin-O staining is unique to the hyaline cartilage that lines the articular surfaces of the joints. As shown in FIG. 5, the two pieces of tissue have begun to integrate with each other in the fibrin-filled space between the original tissue pieces. The dark red stain (original proof) indicates that the tissue has remained viable and is maintaining a normal hyaline-cartilage phenotype with regard to S-GAG composition.
Example 3
Minced JHAC Implantation
Minced JHAC was implanted into Spanish goats using the methods of the invention, further demonstrating the usefulness of the invention. A six (6) mm circular defect was created in the weight-bearing region of the right, medial femoral condyle. Minced juvenile human articular cartilage was placed into the defect which was subsequently filled with human fibrin and covered with a live periosteal flap sutured into the surrounding cartilage. The limb was then set in a modified Thomas splint for a period of six weeks during which the animal was able to ambulate without exposing the repaired site to full weight-bearing forces.
FIG. 6 shows the repaired medial femoral condyle (right side of photograph) six weeks after implantation. The surface of the repair site appears relatively smooth and the tissue has been retained within the original defect. A 1 mm thick section through the defect site is shown in FIG. 7. The section shows that the defect is filled with a white, translucent material including the original tissue pieces. Fluorescent probes stain the nuclear DNA red and identify dead cells while green probes stain living cells within the cartilage matrix. The juvenile cartilage is embedded into a chondro-conductive matrix composed of fibrin that is less cellular. Microscopic examination of the section using a viability-indicating stain indicates that both the original tissue and cells that have migrated into the fibrin matrix stain green (original proof) and are therefore viable (FIG. 8).
Safranin-O stained histological sections indicate that the defect site is populated not only by the original implanted tissue, but also by cells that have migrated into the defect site as illustrated by FIG. 9. The original tissue retains the red stain (original proof) indicating S-GAG in the extracellular matrix while the cell-populated matrix surrounding the transplanted tissue has not yet been replaced with a hyaline-like extracellular matrix. The juvenile cartilage is embedded into a chondro-conductive matrix composed of fibrin.
These data demonstrate the successful repair of a chondral defect with a viable tissue construct containing juvenile hyaline cartilage according to one embodiment of the present invention.
Other Embodiments
It is to be understood that the present invention has been described in detail by way of illustration and example in order to acquaint others skilled in the art with the invention, its principles, and its practical application. Particular formulations and processes of the present invention are not limited to the descriptions of the specific embodiments presented, but rather the descriptions and examples should be viewed in terms of the claims that follow and their equivalents. While some of the examples and descriptions above include some conclusions about the way the invention may function, the inventors do not intend to be bound by those conclusions and functions, but puts them forth only as possible explanations.
It is to be further understood that the specific embodiments of the present invention as set forth are not intended as being exhaustive or limiting of the invention, and that many alternatives, modifications, and variations will be apparent to those of ordinary skill in the art in light of the foregoing examples and detailed description. Accordingly, this invention is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and scope of the following claims.
REFERENCES CITED
All publications, patents, patent applications and other references cited in this application are herein incorporated by reference in their entirety as if each individual publication, patent, patent application or other reference were specifically and individually indicated to be incorporated by reference.

## Claims

1. A method of treating an ostechondral defect, comprising:
disposing an osteo-conductive matrix in the defect;
implanting cadaveric, allogenic human juvenile cartilage particles including viable chondrocytes into the defect; and
depositing a chondro-conductive matrix into the defect.

2. The method of claim 1, wherein the osteo-conductive matrix is disposed in the defect prior to implanting the cartilage particles.

3. The method of claim 1 or 2, wherein the cartilage particles are implanted and the chondro-conductive matrix is deposited simultaneously.

4. The method of claim 3, wherein the cartilage particles and the chondro-conductive matrix comprise a single construct.

5. The method of claim 4, wherein a preformed single construct is produced by delivering the cartilage particles and the chondro-conductive matrix to a mold.

6. The method of claim 4, wherein the preformed single construct is attached to the osteo-conductive matrix or cartilage or bone adjacent the defect by gluing.

7. The method of claim 3, wherein the cartilage particles are implanted and the chondro-conductive matrix is deposited through a cannulated device.

8. The method of claim 7, wherein the cartilage particles and the chondro-conductive matrix are mixed during deposition.

9. The method of claim 1, wherein the cartilage particles are implanted and the chondro-conductive matrix is deposited sequentially.

10. The method of claim 9, wherein chondro-conductive matrix is deposited after cartilage particles are implanted into the defect.

11. The method of claim 1, further comprising applying a retainer to the defect.

12. The method of claim 11, wherein the retainer comprises a glue.

13. The method of claim 1, wherein the osteo-conductive matrix is disposed up to the tide mark adjacent the osteochondral defect.

14. The method of claim 1, wherein the osteo-conductive matrix is selected from the group consisting of a porous solid, semisolid, paste or gel.

15. The method of claim 14, wherein the osteo-conductive matrix comprises a porous solid.

16. The method of claim 15, wherein the porous solid comprises an interconnected structure.

17. The method of claim 16, wherein the porous solid comprises cancellous bone.

18. The method of claim 1, wherein the osteo-conductive matrix is selected from the group consisting of bone or a calcium phosphate containing composition.

19. The method of claim 18, wherein the bone is demineralized.

20. The method of claim 1, further comprising removing the cartilage particles from a container including a biocompatible storage solution.

21. The method of claim 1, wherein the cartilage particles have a dimension from about one to about three millimeters.

22. The method of any one of claims 1, 2, 9, 11, 15 or 20, wherein the cartilage particles range in size from about 1 to about 27 mm3.

23. The method of claim 1, wherein the cartilage particles comprise articular cartilage.

24. The method of claim 1, wherein the chondro-conductive matrix is selected from the group consisting of plasma-based adhesives or sealants, and protein-based adhesives or sealants, natural adhesives or sealants and any combination thereof.

25. The method of claim 24, wherein the chondro-conductive matrix is fibrin.

26. The method of claim 1, 2, 9, 11, 15 or 20, wherein the cartilage particles are from cadaveric juvenile donors less than fifteen years of age.

27. The method of claim 26, wherein the cartilage particles are from cadaveric juvenile donors less than two years of age.

28. The method of claim 26, wherein the cartilage particles are from cadaveric juvenile donors from about 20 weeks to about 13 years of age.