Engineered osteochondral construct for treatment of articular cartilage defects

Abstract

An implant for articular cartilage repair includes (1) a three-dimensional body formed of cancellous bone having a demineralized section that contains bone morphogenetic proteins (BMP's) that are released by the demineralization but retained in the body, and (2) a cartilage layer formed on a surface of the demineralized section. The cartilage layer is formed by a method including the steps of (a) isolating chondrocytes from articular cartilage of a donor; (b) cultivating the isolated chondrocytes in a medium; (c) adding the cultivated chondrocytes to the demineralized section of the body, whereby the cultivated chondrocytes are stimulated by the BMP's retained in the body; and (d) incubating the cultivated chondrocytes to form a plurality of layers of chondrocytes on the demineralized section, wherein the plurality of layers of chondrocytes forms the cartilage layer.

1 . An implant for articular cartilage repair, comprising a three-dimensional body formed of cancellous bone and having a demineralized section, the demineralized section containing bone morphogenetic proteins (BMP's) that are released by the demineralization but retained in said body, and a cartilage layer formed on a surface of the demineralized section, said cartilage layer being formed by a method including the steps of:
 (a) isolating chondrocytes from articular cartilage of a donor;   (b) cultivating the isolated chondrocytes in a medium;   (c) adding the cultivated chondrocytes to the demineralized section of said body, whereby the cultivated chondrocytes are stimulated by the BMP's retained in said body; and   (d) incubating the cultivated chondrocytes to form a plurality of layers of chondrocytes on the demineralized section, wherein the plurality of layers of chondrocytes forms said cartilage layer.   
     
     
         2 . The implant as claimed in  claim 1 , wherein the plurality of layers of chondrocytes includes four layers. 
     
     
         3 . The implant as claimed in  claim 1 , wherein the chondrocytes are allograft chondrocytes. 
     
     
         4 . The implant as claimed in  claim 3 , wherein the donor is less than 50 years of age. 
     
     
         5 . The implant as claimed in  claim 3 , wherein the donor is alive. 
     
     
         6 . The implant as claimed in  claim 3 , wherein the donor is deceased. 
     
     
         7 . The implant as claimed in  claim 1 , wherein the chondrocytes are autograft chondrocytes. 
     
     
         8 . The implant as claimed in  claim 1 , wherein said body is formed of allograft cancellous bone. 
     
     
         9 . The implant as claimed in  claim 1 , wherein step (b) includes placing the surface of the demineralized section in a culture vessel and preparing the surface of the demineralized section for cell seeding. 
     
     
         10 . The implant as claimed in  claim 1 , wherein step (d) is performed until said cartilage layer has a thickness in a range of from 2 mm to 5 mm. 
     
     
         11 . The implant as claimed in  claim 1 , wherein said body includes pores having a size that represents a multiple of the cell volume of a chondrocyte. 
     
     
         12 . The implant as claimed in  claim 1 , wherein step (d) is performed for a period of at least 40 days. 
     
     
         13 . The implant as claimed in  claim 1 , wherein the cell density of the chondrocytes in said cartilage layer is about 10 million cells per cm 3 . 
     
     
         14 . The implant as claimed in  claim 1 , wherein all of said body is demineralized. 
     
     
         15 . The implant as claimed in  claim 1 , wherein the demineralized section has a depth of approximately 2 mm. 
     
     
         16 . The implant as claimed in  claim 15 , wherein said body includes a mineralized section and a boundary layer formed between the demineralized section and the mineralized section, the boundary layer having a thickness of about 50 microns. 
     
     
         17 . The implant as claimed in  claim 1 , wherein said body includes pores having a size that ranges from 10 to 100 microns. 
     
     
         18 . The implant as claimed in  claim 1 , wherein step (b) includes expanding the chondrocytes in a two-dimensional culture until the chondrocytes show a dedifferentiated fibroblast-like phenotype. 
     
     
         19 . The implant as claimed in  claim 1 , wherein step (d) is performed until said cartilage layer has a thickness of approximately 2.0 mm. 
     
     
         20 . A construct for repairing an articular cartilage defect, said construct comprising a body entirely formed from substantially demineralized bone. 
     
     
         21 . The construct as claimed in  claim 20 , wherein said body contains bone morphogenetic proteins (BMPs). 
     
     
         22 . The construct as claimed in  claim 20 , wherein said body is porous. 
     
     
         23 . The construct as claimed in  claim 22 , wherein said body includes pores having a size that represents a multiple of the cell volume of a chondrocyte. 
     
     
         24 . The construct as claimed in  claim 22 , wherein said pores have a size that ranges from 10 to 100 microns. 
     
     
         25 . The construct as claimed in  claim 20 , wherein said body is sterile. 
     
     
         26 . The construct as claimed in  claim 20 , wherein said body is spongy. 
     
     
         27 . The construct as claimed in  claim 20 , wherein said body is formed from allograft bone. 
     
     
         28 . The construct as claimed in  claim 20 , wherein said body has at least one surface which contains chondrocytes. 
     
     
         29 . The construct as claimed in  claim 28 , wherein said chondrocytes are allograft chondrocytes. 
     
     
         30 . The construct as claimed in  claim 28 , wherein said chondrocytes have a cell density that ranges from about 0.2 million to about 10 million cells per cm 3 . 
     
     
         31 . The construct as claimed in  claim 28 , wherein said chondrocytes cover the entirety of said at least one surface of said body. 
     
     
         32 . The construct as claimed in  claim 31 , further comprising an extracellular matrix that surrounds said chondrocytes. 
     
     
         33 . The construct as claimed in  claim 31 , further comprising at least one cartilage layer overlying said at least one surface. 
     
     
         34 . The construct as claimed in  claim 33 , wherein said cartilage layer has a thickness of approximately 2 millimeters. 
     
     
         35 . The A construct as claimed in  claim 33 , wherein said at least one cartilage layer has a cell density that ranges from about 0.2 million to about 10 million cells per cm 3 . 
     
     
         36 . The construct as claimed in  claim 31 , further comprising a multiplicity of cartilage layers overlying said at least one surface of said body. 
     
     
         37 . The construct as claimed in  claim 36 , wherein said multiplicity of cartilage layers has a thickness of approximately 2 millimeters.