Placental Tissue Grafts and Improved Methods of Preparing and Using the Same

• US 20080046095A1
• Filed: 08/17/2007
• Published: 02/21/2008
• Est. Priority Date: 08/17/2006
• Status: Active Grant

• Current Assignee: Mimedx Group Incorporated
• Original Assignee: Surgical Biologics, Inc.
• Inventors: Daniel, John
• Granted Patent: US 8,372,437 B2
• Time in Patent Office: Days
• US Class Current: 623/23.74
• 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 placenta membrane tissue grafts, comprising the steps of:

a. obtaining a placenta from a subject, wherein the placenta includes an amniotic membrane layer and a chorion tissue layer;

b. cleaning the placenta in a solution;

c. separating the chorion tissue layer from the amniotic membrane layer;

d. mounting a selected layer of either the chorion tissue layer or the amniotic membrane layer onto a surface of the drying fixture;

e. dehydrating the selected layer on the drying fixture; and

f. thereafter, cutting the selected layer into a plurality of placenta membrane tissue grafts.

2. The method of claim 1 wherein the placenta membrane tissue grafts are amniotic membrane tissue grafts.

3. The method of claim 2 wherein the amniotic membrane layer has a stromal side and an opposite, basement side, and wherein the amniotic membrane layer is mounted onto the drying fixture with the basement side facing down and stromal side facing up.

4. The method of claim 1 wherein the placenta membrane tissue grafts are chorion tissue grafts.

5. The method of claim 1 wherein the drying fixture includes a texture or design adapted to emboss such texture or design into the placenta membrane tissue grafts during the step of dehydration.

6. The method of claim 5 wherein the texture or design embossed into the placenta membrane tissue enable a user to identify a top and bottom surface of the placenta membrane tissue.

7. The method of claim 1, wherein the placenta is cleaned in a hyperisotonic solution.

8. The method of claim 7, wherein the hyperisotonic solution comprises NaCl concentration in a range of from about 30% to about 10%.

9. The method of claim 1, further comprising the step of, after separation of the chorion tissue layer from the amniotic membrane layer, soaking the selected layer in an antibiotic solution.

10. The method of claim 9, further comprising the step of rinsing the selected layer to remove the antibiotic solution.

11. The method of claim 1, further comprising the step of, after separation of the chorion tissue layer from the amniotic membrane layer, physically cleaning the selected layer to remove blood clots and other contaminates.

12. The method of claim 1, wherein the step of dehydrating the selected layer further comprises placing the drying fixture in a breathable bag and heating the bag for a predetermined period of time.

13. The method of claim 12, wherein the bag is heated at a temperature of between 35 degrees and 50 degrees Celcius and wherein the predetermined period of time is between 30 and 120 minutes.

14. The method of claim 1, wherein the surface of the drying fixture has a plurality of grooves that defines the outer contours of each of the plurality of placenta membrane tissue grafts and wherein the step of cutting comprises cutting the selected layer along the grooves.

15. The method of claim 1, wherein the surface of the drying fixture has a plurality of raised edges that define the outer contours of each of the plurality of placenta membrane tissue grafts and wherein the step of cutting comprises rolling a roller across the top of the selected layer and pressing the selected layer against the raised edges.

16. The method of claim 1, further comprising the step of mounting one or more additional layers of chorion tissue or amniotic layer onto the surface of the drying fixture prior to the step of dehydration to create a plurality of laminated placenta membrane tissue grafts having a thickness and strength greater than a single layer of placenta membrane tissue grafts.

17. The method of claim 1, wherein each of the plurality of placenta membrane tissue grafts is rehydrated prior to use of the respective graft for a medical procedure.

18. A tissue graft, comprising:

a dehydrated, placenta tissue having a top and bottom surface and an outer contour sized and shaped for use in a suitable medical procedure;

wherein a texture or design is embossed within the dehydrated, placenta tissue and wherein the embossment distinguishes the top from the bottom surface of the placenta tissue; and

wherein the dehydrated, placenta tissue graft is usable in the suitable medical procedure after being rehydrated.

19. The tissue graft of claim 18 wherein the dehydrated, placenta tissue comprises either an amniotic membrane layer or a chorion tissue layer.

20. The tissue graft of claim 18 wherein the dehydrated, placenta tissue comprises a two or more layers of amniotic membrane and chorion tissue alone or in combination with each other.