Placental tissue grafts and improved methods of preparing and using the same

Abstract

Described herein are tissue grafts derived from the placenta. The grafts are composed of at least one layer of amnion tissue where the epithelium layer has been substantially removed in order to expose the basement layer to host cells. By removing the epithelium layer, cells from the host can more readily interact with the cell-adhesion bio-active factors located onto top and within of the basement membrane. Also described herein are methods for making and using the tissue grafts. The laminin structure of amnion tissue is nearly identical to that of native human tissue such as, for example, oral mucosa tissue. This includes high level of laminin-5, a cell adhesion bio-active factor show to bind gingival epithelia-cells, found throughout upper portions of the basement membrane.

What is claimed is: 
     
         1 . A tissue graft comprising a first membrane comprising an amnion and one or more additional membranes laminated to the first membrane, wherein the first membrane comprises an exposed basement membrane and stromal layer, and the one or more additional membranes are adjacent to the stromal layer. 
     
     
         2 . The graft of  claim 1 , wherein the at least one membrane comprises amnion, chorion, allograft pericardium, allograft acellular dermis, amniotic membrane, Wharton's jelly, purified xenograft Type-1 collagen, biocellulose polymers or copolymers, biocompatible synthetic polymer or copolymer films, purified small intestinal submucosa, bladder acellular matrix, cadaveric fasia, or any combination thereof 
     
     
         3 . The graft of  claim 1 , wherein the at least one membrane comprises amnion, chorion, or a combination thereof. 
     
     
         4 . The graft of  claim 1 , wherein at least two amnion membranes are laminated to the first membrane. 
     
     
         5 . The graft of  claim 1 , wherein four amnion membranes are laminated to the first membrane. 
     
     
         6 . The graft of  claim 1 , wherein a layer of chorion is laminated to the first membrane. 
     
     
         7 . The graft of  claim 1 , wherein the tissue graft comprises a second membrane comprising an exposed basement membrane and stromal layer, wherein the stromal layer of the second membrane is laminated to the exposed additional membrane. 
     
     
         8 . The graft of  claim 1 , wherein at least one of the membranes comprises a naturally occurring growth factor, a platelet concentrate, a bone marrow aspirate, stem cells, or an antibiotic. 
     
     
         9 . The graft of  claim 1 , wherein the number of membranes laminated to the first membrane is from 1 to 10. 
     
     
         10 . The graft of  claim 1 , wherein the graft has a thickness from 0.2 mm to 10 mm. 
     
     
         11 . The graft of  claim 1 , wherein the graft comprises a plurality of holes penetrating the graft. 
     
     
         12 . A method for treating a wound present on mucosal tissue of a subject comprising applying the tissue graft of  claim 1  to the wound. 
     
     
         13 . The method of  claim 12 , wherein the mucosal tissue is present in the oral cavity, nose, throat, vagina, or rectum of the subject. 
     
     
         14 . A method for treating a dental defect in a subject comprising applying the tissue graft of  claim 1  to the defect. 
     
     
         15 . The method of  claim 14 , wherein the dental defect comprises a gingival recession, a root carie, or an exposed root. 
     
     
         16 . The method of  claim 14 , wherein the graft is applied to directly to the surface of a tooth root. 
     
     
         17 . The method of  claim 14 , wherein prior to applying the tissue graft to the defect, contacting the graft with one or more bioactive molecules to be delivered to the defect. 
     
     
         18 . The use of the tissue graft in  claim 1  for eliminating frenum pull, patella regeneration, treating mouth sores and oral lesions, guide tissue bone regeneration, periodontal regeneration, oral reconstruction, vestibuloplasty, tissue regeneration around dental implants, esophagus reconstruction, plastic surgery, cosmetic surgery, peripheral arterial disease, ladder reconstruction, orbital floor repair, treatment of foot ulcers, corneal repair, adhesion barrier in spinal implant procedures, adhesion barrier in general surgery, use as vascular conduits, increasing the zone of gingival, or genitourinary reconstruction. 
     
     
         19 . A method for preparing a tissue graft, comprising the steps:
 (a) obtaining a placenta from a subject, wherein the placenta comprises an amniotic membrane layer and a chorion tissue layer;   (b) cleaning the placenta;   (c) separating the chorion tissue layer from the amnion layer, wherein the amnion comprises epithelium cells adjacent to a basement membrane;   (d) removing substantially all of the epithelium cells to expose the basement membrane of the amnion to produce a first membrane;   (e) mounting the first membrane onto a surface of a drying fixture, wherein the basement membrane of the first membrane is adjacent to the surface of the drying fixture;   (f) mounting one or more additional membranes on the first membrane to produce a layered tissue graft; and   (g) dehydrating the layered tissue graft on the drying fixture.   
     
     
         20 . The method of  claim 19 , wherein the placenta is cleaned with a hyperisotonic solution. 
     
     
         21 . The method of  claim 20 , wherein the hyperisotonic solution comprises NaCl concentration in a range of from about 10% to about 30%. 
     
     
         22 . The method of  claim 19 , wherein after step (c) but prior to step (d), soaking the amnion in an antibiotic solution. 
     
     
         23 . The method of  claim 22 , further comprising the step of rinsing the amnion to remove the antibiotic solution. 
     
     
         24 . The method of  claim 19 , wherein after step (c) but prior to step (d), physically cleaning the amniotic membrane to remove blood clots and other contaminates. 
     
     
         25 . The method of  claim 19 , wherein step (d) comprises scraping the epithelium layer to substantially remove the epithelium layer. 
     
     
         26 . The method of  claim 19 , wherein the dehydrating step (e) further comprises placing the drying fixture with the layered tissue graft mounted to the fixture in a breathable bag and heating the bag in an oven or incubator chamber for a predetermined period of time. 
     
     
         27 . The method of  claim 26 , wherein the oven or incubator chamber is heated at a temperature of between 35° C. and 50° C. between 30 and 120 minutes. 
     
     
         28 . The method of  claim 19 , wherein the surface of the drying fixture has a plurality of grooves that defines the outer contours of each of the plurality of placenta. 
     
     
         29 . The method of  claim 19 , wherein the drying fixture includes a texture or design adapted to emboss such texture or design into the basement membrane during dehydration. 
     
     
         30 . The method of  claim 19 , wherein the one or more additional membranes comprises amnion, chorion, allograft pericardium, allograft acellular dermis, amniotic membrane, Wharton's jelly, purified xenograft Type-1 collagen, biocellulose polymers or copolymers, biocompatible synthetic polymer or copolymer films, purified small intestinal submucosa, bladder acellular matrix, cadaveric fasia, or any combination thereof. 
     
     
         31 . The method of  claim 19 , wherein the one or more additional membranes comprises chorion, amnion, or a combination thereof. 
     
     
         32 . The method of  claim 31 , wherein after the tissue graft is dehydrated, piercing the layered tissue graft to produce one or more holes in the graft. 
     
     
         33 . A tissue graft produced by the method of  claim 19 . 
     
     
         34 . A tissue graft produced by the method of  claim 32 .