PTAB

IPR2015-00664

MUSCuLoSkeletal Transplant Foundation v. MiMedx Group Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Placental Tissue Grafts
  • Brief Description: The ’437 patent discloses a dehydrated, laminated tissue graft derived from placental membranes. The patent claims the graft as a product-by-process, where the process consists of isolating amnion and chorion layers, washing them, laminating them together, and dehydrating the final graft.

3. Grounds for Unpatentability

Ground 1: Anticipation over Klen - Claims 1-2 are anticipated by Klen under 35 U.S.C. §102.

  • Prior Art Relied Upon: Klen (a 1971 article titled "Preparation of chorion and/or amnion grafts used in burns").
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Klen, a reference not cited during prosecution, discloses every element of the claimed product-by-process. Klen described preparing combined amnion-chorion grafts for treating burns. Petitioner mapped Klen’s process to the claim limitations, arguing it taught: isolating intact amnion and chorion layers as part of preparing amnion-only, chorion-only, and combined grafts; washing the membranes in saline to remove blood clots; combining the amnion and chorion in a stacked configuration (“laminating”); and dehydrating the graft via freeze-drying. Petitioner contended that Klen’s process included only the claimed steps, thereby satisfying the "consisting of" language of claim 1.
    • Key Aspects: Petitioner asserted that since Klen taught making amnion-only and chorion-only grafts, a person of ordinary skill in the art (POSITA) would understand that this necessarily required the step of separating (isolating) the amnion from the chorion.

Ground 2: Obviousness over Vishwakarma and Sulner/Shenaq - Claim 1 is obvious over Vishwakarma in view of Sulner or Shenaq under 35 U.S.C. §103.

  • Prior Art Relied Upon: Vishwakarma (a 1986 journal article), Sulner (Application # 2007/0038298), and Shenaq (WO 93/10722).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Vishwakarma taught a multi-layered amniotic membrane graft for use in hip arthroplasty. Its preparation method disclosed most of the claimed steps: isolating an intact amnion layer from the chorion, washing the amnion, laminating multiple amnion layers together, and dehydrating the graft by air drying. However, Vishwakarma did not explicitly teach including a chorion layer in the final graft or washing the chorion. Sulner and Shenaq were introduced to supply these missing elements. Sulner disclosed a laminated biofabric containing "both a chorionic membrane and an amniotic membrane," and Shenaq taught making grafts from amnion and chorion sheets "wrapped in layers."
    • Motivation to Combine: A POSITA would combine the teachings to improve the graft taught by Vishwakarma. Sulner taught laminating placental layers to provide "greater stiffness and durability." Shenaq showed that amnion and chorion are interchangeable for some applications. Petitioner argued a POSITA would be motivated to include the readily available chorion to conserve placental tissue resources, increase graft thickness and strength, and potentially add beneficial biological properties for wound healing, as chorion is known to contain angiogenic factors.
    • Expectation of Success: Because both amnion and chorion were well-known materials for tissue grafts, a POSITA would have a reasonable expectation that a combined amnion-chorion graft based on Vishwakarma's method would be successful for its intended purpose.

Ground 3: Obviousness over Tseng and Sulner/Shenaq - Claim 1 is obvious over Tseng in view of Sulner or Shenaq under §103.

  • Prior Art Relied Upon: Tseng (Patent 6,152,142), Sulner (Application # 2007/0038298), and Shenaq (WO 93/10722).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Tseng taught an amniotic membrane graft where the amnion is separated from the chorion, washed, and layered. Tseng’s process thus taught isolating, washing, and laminating the amnion. However, Tseng’s graft did not include a chorion layer and was preserved by freezing, not dehydration. Sulner and Shenaq were again relied upon to teach the inclusion of a chorion layer. Sulner was also cited for its teaching of dehydrating laminated placental grafts for storage, noting the dehydrated product "can be stored for several years with no alteration in biochemical or structural integrity."
    • Motivation to Combine: A POSITA would be motivated to modify Tseng’s graft to include a chorion layer for the same reasons articulated in Ground 2 (e.g., increased durability, conservation of tissue). Furthermore, a POSITA would be motivated to substitute Sulner’s dehydration for Tseng’s freezing. Dehydration was a well-known, conventional alternative for preserving tissue grafts that offered significant advantages, such as storage at room temperature and easier handling compared to frozen grafts, which require specialized freezers and a lengthy thawing process.
    • Expectation of Success: Substituting one known preservation technique (dehydration) for another (freezing) to achieve a predictable improvement in storage and handling would have been obvious with a high expectation of success.
  • Additional Grounds: Petitioner asserted additional obviousness challenges, including grounds based on Klen in view of Shimazaki (a Japanese patent publication) and Ward (a 1989 journal article) in view of Sulner or Shenaq, but relied on similar modification theories.

4. Key Claim Construction Positions

  • "laminating the amnion layer and the chorion layer together": Petitioner argued that since the Patent Owner did not construe this term in related litigation, it should be given its broadest reasonable interpretation: "combining the isolated amnion layer and the isolated chorion layer in a stacked configuration (i.e., one on top of another)."
  • "intact amnion layer": Petitioner adopted the Patent Owner's proposed construction from related litigation for the purposes of the IPR, which defined the term as an "Amnion layer separated from native chorion layer which retains a sufficient number of cells to support the desired purpose of the tissue graft." Petitioner argued the prior art met this construction because the disclosed grafts were successfully used in patients, necessarily implying they retained sufficient cells.
  • "washing and substantially cleaning...": Similarly, Petitioner adopted the Patent Owner's construction of this term as reducing "the amount of blood clots and other extraneous tissue." Petitioner argued that simple washing steps in the prior art would inherently remove blood clots and that removal of the intermediate spongy layer (as extraneous tissue) was also taught or obvious.

5. Key Technical Contentions (Beyond Claim Construction)

  • Product-by-Process Claim Analysis (Thorpe Analysis): Petitioner presented a dual analysis for the product-by-process claim. As a central contention, Petitioner argued that under the Thorpe analysis, the process limitations of claim 1 should be disregarded, and the claim should be construed as a pure product claim for a "dehydrated, laminated tissue graft" consisting of one layer of intact amnion and one layer of chorion. Petitioner asserted that this resulting product structure was rendered obvious or anticipated by the same prior art references, even if those references used a different process to create the graft.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1 and 2 of Patent 8,372,437 as unpatentable under 35 U.S.C. §§102 and 103.