PTAB

IPR2019-00571

RTI Surgical Inc v. LifeNet Health

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1. Case Identification

2. Patent Overview

  • Title: Plasticized Soft Tissue Grafts and Methods of Making and Using Same
  • Brief Description: The ’200 patent discloses methods for preserving soft tissue grafts by incorporating chemical compounds, termed “plasticizers” like glycerol, into the graft’s internal matrix. The process is intended to produce a pliable, non-brittle graft that does not require rehydration before implantation, with a key limitation being that the plasticizer is not removed from the internal matrix prior to transplantation.

3. Grounds for Unpatentability

Ground 1: Anticipation by Walker - Claims 1-3, 5, 7-10, 12, and 15 are anticipated by Walker

  • Prior Art Relied Upon: Walker (WO 98/07452).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Walker, which was not cited during prosecution, discloses every limitation of the challenged claims. Walker describes a method for sterilizing biological materials (e.g., vascular tissues) for implantation by first cleaning them (storing in ethanol) and then incubating them with a protective chemical compound, explicitly naming glycerol, to preserve flexibility and prevent brittleness. Petitioner contended that Walker’s teaching to drain or wash the material to remove excess glycerol does not constitute the deliberate removal of plasticizer from the internal matrix of the graft, as a POSITA would understand this step only removes surface-level glycerol. Walker further discloses that the treated material retains its physical properties, thus anticipating the claimed "plasticized soft tissue graft."

Ground 2: Anticipation by Livesey - Claims 1-3, 7-8, 10, and 15 are anticipated by Livesey

  • Prior Art Relied Upon: Livesey (Patent 5,336,616).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Livesey, which was cited but not substantively addressed during prosecution, also anticipates the key claims. Livesey discloses a method for processing and preserving acellular, collagen-based tissue for transplantation. The process includes cleaning the tissue to remove antigenic cellular components (decellularization) and incubating it in a cryosolution containing "cryoprotectants" (including glycerol, sucrose, and propylene glycol, which overlap with the ’200 patent’s "plasticizers") until complete penetration is achieved. Petitioner argued that Livesey’s method contains no steps for removing these cryoprotectants from the internal matrix before use and teaches that the process maintains the structural integrity of the tissue, thereby meeting all limitations of the independent claims.

Ground 3: Obviousness over Walker or Livesey in view of Werner - Claim 4 is obvious over Walker or Livesey in view of Werner

  • Prior Art Relied Upon: Walker (WO 98/07452) or Livesey (Patent 5,336,616) in view of Werner (Patent 4,357,274).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground specifically addressed the limitation in dependent claim 4 that the graft is "suitable for direct transplant into a human without rehydration." Petitioner argued that if Walker or Livesey are found not to explicitly teach this feature, Werner provides the missing element. Werner discloses a process for treating sclera protein transplants with glycerin, stating that the resulting product is soft and that "no rehydration is necessary prior to implantation."
    • Motivation to Combine: A POSITA would combine Werner’s teachings with the methods of Walker or Livesey to simplify the overall process for preparing a tissue graft. Achieving direct implantability without the need for a separate rehydration step was a known and desirable goal in the art.
    • Expectation of Success: Since Werner teaches a similar process of impregnating tissue with glycerol, a POSITA would have had a high expectation of success in applying its teaching of avoiding rehydration to the similar glycerol-based preservation methods taught in Walker and Livesey to achieve a predictable, improved result.

  • Additional Grounds: Petitioner asserted fallback obviousness challenges over Walker (Ground 2) and Livesey (Ground 4) for nearly all challenged claims. The core of these arguments was that even if the references do not explicitly teach that the plasticizers are "not removed," a POSITA would have found it obvious to retain them in the internal matrix to achieve the well-known benefits of improved pliability, preservation, and avoidance of tissue degradation caused by extensive washing.

4. Key Claim Construction Positions

  • “cleaned”: Petitioner argued that a POSITA would understand the cleaning process described in the ’200 patent’s examples (a brief soak in a dilute solution) as only partially removing cellular elements from the soft tissue. This construction was important for mapping to prior art references like Walker, which also disclosed processes (e.g., ethanol storage) that would result in partial, rather than complete, cleaning.
  • “not removed from [the] internal matrix”: Petitioner highlighted that a court in related litigation determined this phrase required no construction beyond its plain meaning, which distinguishes deliberate removal of the plasticizer from incidental loss. This was central to Petitioner’s argument that Walker’s teaching to wash away excess glycerol did not anticipate this limitation, as it was not a deliberate process to remove glycerol from within the tissue matrix itself.

5. Key Technical Contentions (Beyond Claim Construction)

  • Petitioner’s arguments for all grounds relied on the central technical contention that a POSITA in 1998 would have known it was advantageous to not remove plasticizers like glycerol from a tissue graft prior to implantation. Petitioner asserted that the prior art widely recognized that retaining glycerol preserved the tissue’s pliability, provided antiseptic benefits, was non-toxic, and crucially, avoided the extensive washing steps required for removal, which were known to risk damaging the tissue’s delicate structural architecture. This understanding framed why a POSITA would interpret the prior art as teaching non-removal or, alternatively, would have been motivated to modify prior art processes to retain the plasticizer.

6. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-10, 12-13, and 15 of the ’200 patent as unpatentable.