Placental tissue grafts

• US 9,463,207 B2
• Filed: 05/22/2014
• Issued: 10/11/2016
• Est. Priority Date: 08/17/2006
• Status: Active Grant

• Current Assignee: Mimedx Group Incorporated
• Original Assignee: Mimedx Group Incorporated
• Inventors: Daniel, John
• Primary Examiner(s): FOX, ALLISON M
• Application Number:
  US14/285,573
• Publication Number:
  US 20140370068A1
• Time in Patent Office: 873 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: A61K 35/50 Placenta; Placental stem cells; Amniotic fluid; Amnion; Amniotic stem cells
• CPC Class Codes: A61L 2300/412 Tissue-regenerating or healing or proliferative agents
• CPC Class Codes: A61L 2300/60 characterised by a special physical form
• CPC Class Codes: A61L 2430/40 Preparation and treatment of biological tissue for implantation, e.g. decellularisation, cross-linking
• CPC Class Codes: A61L 27/3604 characterised by the human or animal origin of the biological material, e.g. hair, fascia, fish scales, silk, shellac, pericardium, pleura, renal tissue, amniotic membrane, parenchymal tissue, fetal tissue, muscle tissue, fat tissue, enamel
• CPC Class Codes: A61L 27/3683 subjected to a specific treatment prior to implantation, e.g. decellularising, demineralising, grinding, cellular disruption/non-collagenous protein removal, anti-calcification, crosslinking, supercritical fluid extraction, enzyme treatment
• CPC Class Codes: A61L 27/3691 characterised by physical conditions of the treatment, e.g. applying a compressive force to the composition, pressure cycles, ultrasonic/sonication or microwave treatment, lyophilisation
• CPC Class Codes: A61L 27/50 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61L 27/54 Biologically active materials, e.g. therapeutic substances A61L27/227 takes precedence
• CPC Class Codes: A61L 27/58 Materials at least partially resorbable by the body

Abstract

A method for preparing placenta membrane tissue grafts for medical use, includes obtaining a placenta from a subject, cleaning the placenta, separating the chorion tissue from the amniotic membrane, mounting a selected layer of either the chorion tissue or the amniotic membrane onto a drying fixture, dehydrating the selected layer on the drying fixture, and cutting the selected layer into a plurality of tissue grafts. Preferably, the drying fixture includes grooves or raised edges that define the outer contours of each desired tissue graft, after they are cut, and further includes raised or indented logos that emboss the middle area of the tissue grafts during dehydration and that enables an end user to distinguish the top from the bottom side of the graft. The grafts are comprised of single layers of amnion or chorion, multiple layers of amnion or chorion, or multiple layers of a combination of amnion and chorion.

Claims

1. A method for preparing a dehydrated tissue graft, comprising the steps:

a) obtaining a placenta comprising an amnion and a chorion;

b) separating the amnion and the chorion from the placenta;

c) washing and cleaning the amnion and/or the chorion;

d) placing a first layer of amnion or chorion on a drying fixture;

e) adding at least one additional layer of amnion or chorion to the first layer; and

f) dehydrating the tissue graft on the drying fixture, wherein the drying fixture comprises a receiving surface, said surface containing a raised or indented asymmetric texture within a product space which has an otherwise smooth surface;

wherein when at least one layer is amnion, said method does not substantially remove all of the epithelial cells on at least one layer of amnion.

2. The method of claim 1, wherein after step (b) but prior to step (c), soaking the amnion in an antibiotic solution and then substantially removing the antibiotic solution.

3. The method of claim 1, wherein the tissue graft comprises an amnion.

4. The method of claim 1, wherein the tissue graft comprises a chorion.

5. The method of claim 1, wherein the tissue graft comprises an amnion and a chorion.

6. The method of claim 1, wherein the washing step includes contacting the separated amnion with a hypertonic saline solution, wherein the hypertonic saline solution comprises a NaCl concentration from about 10% to about 30%.

7. The method of claim 1, wherein the dehydrating step comprises drying the placental tissue under conditions wherein the placental tissue is retained on the drying surface such that the portion of the placental tissue placed within the product space molds around the texture thereby creating an asymmetric label on the placental tissue, whereby the orientation of the placental tissue is visibly distinguishable by the asymmetric label.

8. The method of claim 7, wherein said label is an embossment.

9. The method of claim 7, wherein said label is a logo, a design, a name, or text.