US 5197985

Here's a concise summary of US patent 5197985, based on the provided patent text and current legal status:

US Patent 5197985

• Title: Method for enhancing the implantation and differentiation of marrow-derived mesenchymal cells
• Assignee: Mesoblast International SÀRL (current assignee as of 2013-11-01). Previous assignees included Case Western Reserve University, Osiris Therapeutics, Inc., and National Institutes of Health (NIH), U.S. Dept. of Health and Human Services (DHHS), U.S. Government.
• Inventors: Arnold I. Caplan, Stephen E. Haynesworth
• Filing Date: 1990-11-16
• Issue Date: 1993-03-30
• Abstract: The invention describes a method and device for improving the implantation and differentiation of marrow-derived mesenchymal cells (also known as mesenchymal stem cells). This method and device offer an effective way to treat disorders of skeletal and other connective tissues.
• Legal Status: Expired - Lifetime. The anticipated expiration date was 2010-11-16.

Plain-Language Overview of Independent Claims:

• Claim 1: This claim describes a method to make human marrow-derived mesenchymal stem cells turn into bone-forming cells. It involves:

  1. Obtaining human mesenchymal stem cells that have been isolated, purified, and grown in culture from a bone marrow sample. This isolation uses a special growth medium that encourages cell growth without differentiation and allows only the mesenchymal stem cells to stick to a surface.
  2. Placing these prepared stem cells onto a porous carrier.
  3. Implanting this cell-loaded porous carrier into a living environment that provides the necessary conditions for the stem cells to change into bone cells.

• Claim 4: This claim outlines a method for repairing skeletal defects. It comprises:

  1. Providing human marrow-derived mesenchymal stem cells that have been grown in culture after being isolated and purified from a bone marrow specimen. The isolation process uses a medium that stimulates stem cell growth without differentiation and selectively adheres only these cells to a substrate.
  2. Applying these cultured stem cells to a porous carrier.
  3. Implanting the porous carrier, containing the cultured and purified human mesenchymal stem cells, into the specific area of defective skeletal tissue.

• Claim 6: This claim details another method for repairing skeletal defects, specifying the preparation of cells from a bone marrow specimen containing both stem cells and bone pieces:

  1. A bone marrow specimen, including human mesenchymal stem cells and bone pieces, is provided.
  2. This specimen is mixed with a medium that promotes stem cell growth without differentiation and ensures only the stem cells adhere to a surface.
  3. Bone pieces are separated from this mixture.
  4. The remaining marrow cells in the mixture are broken down into single cells.
  5. These single cells are cultured, allowing only the human mesenchymal stem cells to selectively adhere to a surface.
  6. Non-adherent material is removed, leaving isolated, culturally expanded human mesenchymal stem cells.
  7. These adherent stem cells are then detached from the surface using a releasing agent.
  8. The isolated and culturally expanded human mesenchymal stem cells are applied to a porous carrier, specifically composed of about 60% hydroxyapatite and about 40% tricalcium phosphate.
  9. Finally, this cell-loaded porous carrier is implanted into the defective skeletal tissue.

• Claim 10: This claim describes a method for guiding human marrow-derived mesenchymal stem cells to differentiate into cartilage-forming cells. It involves:

  1. Providing human marrow-derived mesenchymal stem cells that have been culturally expanded after isolation and purification from a bone marrow specimen, using a medium that fosters undifferentiated growth and selective adherence.
  2. Applying these expanded stem cells to a carrier designed to encourage a round cell shape.
  3. Implanting this carrier, containing the expanded stem cells, into an environment that provides the necessary factors for them to differentiate into cartilage-forming cells.

• Claim 11: This claim outlines a method for repairing damaged articular cartilage. It comprises:

  1. Providing human marrow-derived mesenchymal stem cells that have been culturally expanded from isolated and purified cells obtained from a bone marrow specimen using a specific growth and adherence medium.
  2. Applying these culturally expanded human mesenchymal stem cells to a carrier specifically designed to promote a round cell morphology.
  3. Implanting this carrier, containing the expanded human mesenchymal stem cells, directly into the damaged articular cartilage.

• Claim 12: This claim details a method for repairing damaged articular cartilage, similar to Claim 6 but focused on cartilage repair and a different carrier. It involves:

  1. Providing a bone marrow specimen containing human mesenchymal stem cells and bone pieces.
  2. Adding this specimen to a medium that promotes stem cell growth without differentiation and allows selective adherence of only the human mesenchymal stem cells to a substrate.
  3. Separating the bone pieces from the mixture.
  4. Dissociating the marrow cells into single cells.
  5. Culturing these dissociated cells to selectively adhere the human mesenchymal stem cells to the substrate.
  6. Removing non-adherent material, leaving isolated, culturally expanded stem cells.
  7. Removing these adherent, expanded stem cells from the surface with a releasing agent.
  8. Applying the isolated and culturally expanded human mesenchymal stem cells to a carrier that is specifically designed to promote a round cell shape.
  9. Implanting this carrier, containing the expanded cells, into the damaged articular cartilage.

• Claim 15: This claim describes a method for repairing skeletal defects that utilizes a density gradient for cell separation. It involves:

  1. Providing a bone marrow specimen containing human mesenchymal stem cells.
  2. Mixing the specimen with a medium that stimulates stem cell growth without differentiation and promotes selective adherence of these cells to a substrate.
  3. Processing this mixture through a density gradient to separate cells into low, medium, and high-density fractions.
  4. Extracting the low-density cell fraction from the gradient.
  5. Adding this low-density fraction to the same growth medium.
  6. Culturing this mixture, allowing only the mesenchymal stem cells to selectively adhere to a substrate surface.
  7. Removing any non-adherent material.
  8. Detaching the remaining adherent mesenchymal stem cells from the surface using a releasing agent to recover them.
  9. Applying these recovered isolated mesenchymal stem cells to a porous carrier made of about 60% hydroxyapatite and about 40% tricalcium phosphate.
  10. Implanting this porous carrier, containing the culturally expanded human mesenchymal stem cells, into the skeletal defect.

USPTO and CAFC 2026 Dockets Search:

A search for US Patent 5197985 on Google Patents (which links to USPTO data) confirms its legal status as "Expired - Lifetime" with an anticipated expiration date of November 16, 2010.

Given the patent expired in 2010, there is no active litigation concerning this patent number in the CAFC 2026 dockets. No relevant results were found for "CAFC 2026 dockets 5197985".

As a patent attorney, I have investigated litigation involving US Patent 5197985. Based on my research, there is no known litigation directly involving US Patent 5197985. The search results provided did not yield any cases where this specific patent number was a subject of litigation. The results focused on other unrelated patent disputes and class-action lawsuits.

Proceedings overview

The USPTO ODP API currently shows no AIA trial proceedings on file for US Patent 5,197,985 as of the most recent ingest. Web searches conducted for IPR, PGR, and CBM proceedings related to US5197985 also returned no results, indicating there is no PTAB activity on this patent.

Strategic summary

As there are no AIA trial proceedings on file for US Patent 5,197,985, all claims (1-15) of the patent are currently untested by the PTAB. There is no estoppel landscape to consider, as no petitions have been filed, and thus no claims have been challenged or invalidated through these mechanisms. The absence of PTAB activity suggests that this patent has either not been aggressively asserted in a way that would provoke IPRs, or potential petitioners have not identified strong prior art arguments under §§ 102 or 103 that they believe would lead to institution.

Recommended next steps

Since there is no PTAB activity on US Patent 5,197,985, a defendant facing assertion of this patent has a clear path to potentially filing an IPR, PGR, or CBM petition without concerns about estoppel from previous PTAB trials. The absence of prior challenges means that any defense based on patent invalidity through prior art would need to be thoroughly researched and presented in a new petition. This is a significant consideration, as well-asserted patents often attract IPRs.

Inventors

• Arnold I. Caplan (Individual)
• Stephen E. Haynesworth (Individual)

Original assignee

The original assignee on the issued patent was "Individual," indicating the inventors themselves. It is not determinable from the patent text whether "Individual" shipped a product embodying the claims, or their primary line of business. The current status of "Individual" is not applicable as they were not a corporate entity.

Assignment timeline

• 1994-03-24 (executed) / recorded 1994-03-24 — Reel 006935/0501

  • Conveyance: Assignment
  • Assignor: Arnold I. Caplan; Stephen B. Haynesworth
  • Assignee: Case Western Reserve University
  • Correspondent: R.W. Bosworth, Jr., Bosworth & Associates, 23500 Mercantile Road, Suite D, Beachwood, Ohio 44122.
  • Context: Transfer from inventors to academic institution.

• 2006-06-21 (executed) / recorded 2006-07-25 — Reel 018090/0411

  • Conveyance: Assignment
  • Assignor: Case Western Reserve University
  • Assignee: Osiris Therapeutics, Inc.
  • Correspondent: Scott D. Stimpson, Osiris Therapeutics, Inc., 2001 Aliceanna Street, Baltimore, MD 21231.
  • Context: Transfer from academic institution to biotechnology company.

• 2008-10-03 (executed) / recorded 2008-11-20 — Reel 022137/0942

  • Conveyance: Confirmatory License
  • Assignor: Case Western Reserve University
  • Assignee: National Institutes of Health (NIH), U.S. Dept. of Health and Human Services (DHHS), U.S. Government
  • Correspondent: NIH, Office of Technology Transfer, 6011 Executive Blvd., Suite 325, Rockville, MD 20852-3804.
  • Context: License grant to US Government agency.

• 2009-09-14 (executed) / recorded 2009-10-14 — Reel 023812/0358

  • Conveyance: Confirmatory License
  • Assignor: Case Western Reserve University
  • Assignee: National Institutes of Health (NIH), U.S. Dept. of Health and Human Services (DHHS), U.S. Government
  • Correspondent: NIH, Office of Technology Transfer, 6011 Executive Blvd., Suite 325, Rockville, MD 20852-3804. This correspondent recurs in this chain.
  • Context: Confirmatory license grant to US Government agency.

• 2013-11-01 (executed) / recorded 2013-12-04 — Reel 031174/0200

  • Conveyance: Assignment
  • Assignor: Osiris Therapeutics, Inc.
  • Assignee: Mesoblast International SÀRL
  • Correspondent: Robert A. Parsons, Hogan Lovells US LLP, Columbia Square, 555 Thirteenth Street, NW, Washington, DC 20004.
  • Context: Transfer from biotechnology company to another biotechnology company.

Timeline diagram

timeline
    title Ownership of US 5197985
    1990 : Filed by Inventors
    1993 : Issued
    1994 : Assigned to Case Western Reserve University
    2006 : Assigned to Osiris Therapeutics Inc
    2008 : Licensed to NIH
    2009 : Confirmatory License to NIH
    2013 : Assigned to Mesoblast International SÀRL

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The assignees in the chain (Case Western Reserve University, Osiris Therapeutics, Inc., Mesoblast International SÀRL) appear to be operating entities rather than shell companies.
2. Known asserter in the chain — not present. None of the listed assignees (Case Western Reserve University, Osiris Therapeutics, Inc., National Institutes of Health, Mesoblast International SÀRL) are identified as known patent asserters or NPEs by public lists.
3. Repeat correspondent across the chain — present. The NIH, Office of Technology Transfer, appears as the correspondent for both the 2008-11-20 (Reel 022137/0942) and 2009-10-14 (Reel 023812/0358) confirmatory license recordings.
4. Cascading transfers — not present. The assignments are spaced several years apart, indicating a lack of rapid, consecutive transfers.
5. Pre-litigation transfer — unclear. There is no information provided regarding litigation history for this patent, so it is impossible to assess if any transfers occurred within 6 months of a lawsuit.
6. Bankruptcy fire-sale — not present. There is no indication in the provided information that any of the assignors or assignees underwent bankruptcy proceedings leading to a patent sale.
7. Privateering — not present. There is no information suggesting that an operating company transferred the patent to an NPE to assert on its behalf.
8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at any known defensive aggregator.

Verdict

Insufficient data. While the patent has a clear assignment chain, there is no strong evidence of NPE activity based on the provided information. The assignees appear to be legitimate operating entities or academic/government institutions, and there are no clear signals of shell-entity transfers, known NPE involvement, cascading transfers, or bankruptcy fire-sales as described. Information regarding litigation history would be necessary to assess pre-litigation transfer patterns.

For verification, see the USPTO Assignment Center search page: https://assignmentcenter.uspto.gov/

US Patent 5197985, titled "Method for enhancing the implantation and differentiation of marrow-derived mesenchymal cells," was filed on November 16, 1990, and published on March 30, 1993.

A review of the provided patent text, which is from Google Patents, indicates that there is no distinct "References Cited" section listing patent citations as prior art for US5197985. The patent document primarily refers to scientific journal articles and research papers as background and supporting evidence for the invention. The "Cited By" section on Google Patents lists patents that later cited US5197985, not the prior art for US5197985 itself.

Therefore, the following analysis focuses on the non-patent literature cited within the patent's detailed description, which serves as the disclosed prior art and background for the invention.

Most Relevant Prior Art (Non-Patent Literature) for US5197985

1. Beresford, J. N.: Osteogenic Stem Cells and the Stromal System of Bone and Marrow, Clin. Orthop., 240:270, 1989.

• Full Citation: Beresford, J. N.: Osteogenic Stem Cells and the Stromal System of Bone and Marrow, Clin. Orthop., 240:270, 1989.
• Publication/Filing Date: 1989 (Publication date).
• Brief Description: This article suggested that bone marrow contains "prestromal" cells capable of differentiating into cartilage, bone, and other connective tissue cells. This generally supports the concept of pluripotent stromal stem cells (mesenchymal stem cells) found in bone marrow that can differentiate into various cell lines (osteocytes, chondrocytes, adipocytes).
• Potential Anticipation (35 U.S.C. § 102): This reference broadly anticipates the understanding that marrow contains cells with osteogenic potential, as mentioned in the background of US5197985. It provides foundational knowledge regarding the existence and general differentiation potential of mesenchymal stem cells. It could potentially anticipate the premise in claims related to the provision of mesenchymal stem cells (e.g., elements of claims 1a, 4a, 6a, 10a, 11a, 12a, 15a) if those claims were interpreted to cover merely identifying such cells, rather than the specific isolation, expansion, and differentiation methods claimed. However, US5197985 focuses on the method of isolating, culturing, expanding, and then directing their differentiation using specific carriers, which goes beyond simply recognizing their potential.

2. Ohgushi, H., Goldberg, V., and Caplan, A. Acta Scandia., 60:334-339, 1989.

• Full Citation: Ohgushi, H., Goldberg, V., and Caplan, A. Acta Scandia., 60:334-339, 1989.
• Publication/Filing Date: 1989 (Publication date).
• Brief Description: This study, conducted by the inventor's lab, involved using rat marrow in a composite graft with porous ceramic to fill a segmental defect in the femur of a rat. It showed that bone filled the pores of the ceramic and anchored the ceramic-marrow graft to the host bone.
• Potential Anticipation (35 U.S.C. § 102): This reference directly anticipates the concept of using porous ceramic carriers with marrow-derived cells for bone formation in skeletal defects, as described in US5197985. While it uses rat marrow, the principle of a ceramic-marrow graft to promote bone formation is disclosed. This could potentially anticipate aspects of claims 1b-1c, 4b-4c, 6h-6i, and 15i-15j, particularly the use of a porous carrier (ceramic) for implantation into skeletal defects to promote bone differentiation and repair. However, US5197985 specifies human culturally expanded, isolated, and purified mesenchymal stem cells, which is a key distinction from "rat marrow."

3. Ashton, et al., 1980 (as cited in Diffusion Chambers description).

• Full Citation: Ashton, et al., as referenced for the construction of lucite rings and Millipore filters for diffusion chambers (Ashton, et al., 1980).
• Publication/Filing Date: 1980 (Implied publication date).
• Brief Description: This reference describes the method for constructing diffusion chambers, which were used as a comparative assay method in US5197985 to evaluate the osteo-chondrogenic potential of cultured marrow-derived mesenchymal cells.
• Potential Anticipation (35 U.S.C. § 102): This reference describes a general technique for cell culture and implantation for studying differentiation but does not directly anticipate the specific methods of isolating, expanding, and differentiating mesenchymal stem cells as claimed in US5197985. It provides a methodological tool rather than an inventive concept for mesenchymal cell therapy.

4. Bab, I., Passi-Even, L., Gazit, D., Sekeles, E., Ashton, B. A., Peylan-Ramu, N., Ziv, I., and Ulmansky, M.; Osteogenesis in vivo diffusion chamber cultures of human marrow cells, Bone and Mineral 4; 373, 1988.

• Full Citation: Bab, I., Passi-Even, L., Gazit, D., Sekeles, E., Ashton, B. A., Peylan-Ramu, N., Ziv, I., and Ulmansky, M.; Osteogenesis in vivo diffusion chamber cultures of human marrow cells, Bone and Mineral 4; 373, 1988.
• Publication/Filing Date: 1988 (Publication date).
• Brief Description: This study observed bone formation in diffusion chambers implanted with human marrow from child donors but failed to observe it when whole marrow from older donors was used. US5197985 contrasts its findings with this, noting that their method did achieve bone formation with older donors in ceramic grafts where diffusion chambers failed.
• Potential Anticipation (35 U.S.C. § 102): This paper shows some osteogenic potential of human marrow cells in diffusion chambers, particularly from younger donors. It directly relates to the broad concept of osteogenesis from marrow cells. It could potentially anticipate aspects of claims related to inducing differentiation into bone-forming cells from human marrow (e.g., claims 1, 4, 6, 15), but US5197985 distinguishes itself by demonstrating enhanced differentiation (especially from older donors) and highlighting the superior performance of porous ceramic carriers over diffusion chambers for this purpose.

5. Ashton, B. A., Eaglesom, C. C., Bab, I., and Owen, M. E., Distribution of fibroblastic colony-forming cells in rabbit bone marrow and assay of their osteogenic potential by an in vivo diffusion chamber method, Calcif. Tissue Int., 36:83, 1984.

• Full Citation: Ashton, B. A., Eaglesom, C. C., Bab, I., and Owen, M. E., Distribution of fibroblastic colony-forming cells in rabbit bone marrow and assay of their osteogenic potential by an in vivo diffusion chamber method, Calcif. Tissue Int., 36:83, 1984.
• Publication/Filing Date: 1984 (Publication date).
• Brief Description: This reference showed that cultured rabbit marrow stromal cells differ in their colony-forming potential and osteogenic potential depending on their original proximity to the endosteal surface. Cells closest to the endosteal surface had higher colony-forming efficiency. US5197985 mentions this in the context of explaining why cancellous bone marrow might be more osteogenic than aspirate marrow due to harvesting methods.
• Potential Anticipation (35 U.S.C. § 102): This reference establishes that marrow stromal cells have osteogenic potential and that their properties can vary by location in the bone, and it describes methods for assaying this. It supports the underlying biological principles but does not specifically disclose the claimed human cell isolation, cultural expansion, or specific carrier-based differentiation methods of US5197985. It informs the selection of marrow source (cancellous bone vs. aspirate) but doesn't anticipate the full method.

6. Davies, J. E., Human bone marrow cells synthesize collagen, in diffusion chambers, implanted into the normal rat, Cell. Biol. Int. Rep. 11, 2: 125, 1987.

• Full Citation: Davies, J. E., Human bone marrow cells synthesize collagen, in diffusion chambers, implanted into the normal rat, Cell. Biol. Int. Rep. 11, 2: 125, 1987.
• Publication/Filing Date: 1987 (Publication date).
• Brief Description: This study did not observe bone formation in diffusion chambers inoculated with fresh marrow from a five-year-old female, further supporting the claim in US5197985 that diffusion chambers are not as effective for osteogenesis, especially compared to their ceramic-based method.
• Potential Anticipation (35 U.S.C. § 102): Similar to the Bab et al. (1988) paper, this reference contributes to the understanding of limitations of diffusion chambers for bone formation, reinforcing the novelty of the ceramic carrier approach in US5197985. It shows that human marrow cells can synthesize collagen, a component of connective tissue, but not necessarily form bone under these specific conditions. It does not anticipate the specific methods of isolation, expansion, and differentiation into bone or cartilage using the claimed carriers in US5197985.

7. Ashton, B. A., Cave, F. A., Williamson, M., Sykes, B. C., Couch, M., and Poser, J. W.; Characterization of cells with high alkaline phosphates activity derived from human bone and marrow; preliminary assessment of their osteogenicity, Bone, 5:313-319, 1985.

• Full Citation: Ashton, B. A., Cave, F. A., Williamson, M., Sykes, B. C., Couch, M., and Poser, J. W.; Characterization of cells with high alkaline phosphates activity derived from human bone and marrow; preliminary assessment of their osteogenicity, Bone, 5:313-319, 1985.
• Publication/Filing Date: 1985 (Publication date).
• Brief Description: This study did not observe bone formation in diffusion chambers inoculated with cultured fibroblasts from composite pieces of bone and marrow from children and young adults.
• Potential Anticipation (35 U.S.C. § 102): This reinforces the limitations of diffusion chambers for inducing bone formation from human marrow-derived cells, further highlighting the distinctions of the ceramic carrier method of US5197985. It supports the existence and characterization of osteogenic cells but does not disclose the specific methods for enhancing their implantation and differentiation as claimed.

8. Jaroma, H. J., and Rotsila, V. A., Effect of diffusion chamber pore size on differentiation and proliferation of periosteal cells, Clin. Orthop., 236, 258, 1988.

• Full Citation: Jaroma, H. J., and Rotsila, V. A., Effect of diffusion chamber pore size on differentiation and proliferation of periosteal cells, Clin. Orthop., 236, 258, 1988.
• Publication/Filing Date: 1988 (Publication date).
• Brief Description: This reference discusses the effect of diffusion chamber pore size on cell differentiation and proliferation, suggesting limitations due to diffusion chamber geometry affecting direct accessibility to growth and nutrient factors.
• Potential Anticipation (35 U.S.C. § 102): This study explains some of the mechanistic reasons why diffusion chambers might be less effective, indirectly supporting the inventors' hypothesis in US5197985 that direct access to vasculature in porous ceramics enhances differentiation. It provides background on cell culture conditions but does not anticipate the specific methods or carriers claimed in US5197985.

9. Villanueva, J. E., and Nimni, M. E., Promotion of calvarial cell osteogenesis by endothelial cells in diffusion chambers, J. Cell. Biol., 109, 4, part. 2.42a (abstract).

• Full Citation: Villanueva, J. E., and Nimni, M. E., Promotion of calvarial cell osteogenesis by endothelial cells in diffusion chambers, J. Cell. Biol., 109, 4, part. 2.42a (abstract).
• Publication/Filing Date: Undated (abstract), but appears to be prior to 1990.
• Brief Description: This abstract suggests the promotion of osteogenesis by endothelial cells even in diffusion chambers, providing another angle on cellular interactions in bone formation.
• Potential Anticipation (35 U.S.C. § 102): This abstract touches upon cell-cell interactions influencing osteogenesis. While relevant to the broader field, it does not anticipate the specific methods for isolating, expanding, and differentiating human marrow-derived mesenchymal stem cells using the specific porous carriers claimed in US5197985.

10. Goshima, Jun, Victor M. Goldberg and Arnold I. Caplan, "The Origin of Bone Formed in Composite Grafts of Porous Calcium Phosphate Ceramic and Marrow Cells" (1989) Submitted.

• Full Citation: Goshima, Jun, Victor M. Goldberg and Arnold I. Caplan, "The Origin of Bone Formed in Composite Grafts of Porous Calcium Phosphate Ceramic and Marrow Cells" (1989) Submitted.
• Publication/Filing Date: 1989 (Submitted; publication date unclear but prior to patent filing).
• Brief Description: This work by the inventors' lab (submitted for publication) indicated that bone formation in ceramic grafts is a biphasic phenomenon, with initial donor-derived bone followed by host-derived remodeling and marrow cavity formation.
• Potential Anticipation (35 U.S.C. § 102): This work, although by the same inventors and "submitted," describes the mechanism of bone formation in ceramic-marrow grafts. If this work was publicly available before the filing date of US5197985, it could potentially anticipate the result of bone formation in ceramic carriers and the observation of marrow elements (e.g., in claims 1c, 4c, 6i, 15j). However, the critical elements of US5197985 include the specific method for providing culturally expanded, purified human marrow-derived mesenchymal stem cells and applying them to a porous carrier for differentiation, which this reference describes the outcome of, possibly from earlier, less refined methods. The specific purification and expansion steps are key to US5197985's claims.

Obviousness Analysis of US Patent 5,197,985 under 35 U.S.C. § 103

As of April 26, 2026, US Patent 5,197,985, titled "Method for enhancing the implantation and differentiation of marrow-derived mesenchymal cells," has expired. An analysis of obviousness under 35 U.S.C. § 103 requires evaluating whether the claimed invention, at the time it was made, would have been obvious to a person having ordinary skill in the art (PHOSITA) by combining existing prior art references.

The invention of US5197985 generally relates to methods and devices for enhancing the implantation and differentiation of culturally expanded, purified marrow-derived mesenchymal stem cells (MSCs) into specific connective tissues, such as bone or cartilage, for therapeutic purposes. The patent describes processes for isolating, purifying, and expanding these cells, and then applying them to specific carriers for in vivo differentiation.

The key aspects of the claims in US5197985 are:

• Culturally expanded, isolated, and purified human marrow-derived mesenchymal stem cells as a starting material.
• For bone formation/skeletal repair (Claims 1-9, 15): applying these cells to a porous carrier (specifically, a ceramic comprising about 60% hydroxyapatite and about 40% tricalcium phosphate) and implanting it in vivo.
• For cartilage formation/articular cartilage repair (Claims 10-14): applying these cells to a carrier formatted to promote round cell morphology (e.g., collagen or fibrin) and implanting it in vivo.

The following prior art references are explicitly mentioned within the text of US5197985:

• Beresford, J. N. (1989): "Osteogenic Stem Cells and the Stromal System of Bone and Marrow, Clin. Orthop., 240:270, 1989." This reference suggested that bone marrow contains "prestromal" cells (precursors to mesenchymal stem cells) with the capacity to differentiate into cartilage, bone, and other connective tissue cells.
• Ohgushi, H., Goldberg, V., and Caplan, A. (1989): "Acta Scandia., 60:334-339, 1989." This work, co-authored by one of the inventors of US5197985, described the use of "rat marrow in a composite graft with porous ceramic" to fill a segmental defect in a rat femur, demonstrating bone formation within the ceramic pores and anchoring to host bone.
• Bab, et al. (1988): "Osteogenesis in vivo diffusion chamber cultures of human marrow cells, Bone and Mineral 4; 373, 1988." This study observed bone formation in diffusion chambers implanted with human marrow from child donors, but failed to observe bone when whole marrow from older donors was incubated in diffusion chambers.
• Ashton, et al. (1984, 1985): References such as "Distribution of fibroblastic colony-forming cells in rabbit bone marrow and assay of their osteogenic potential by an in vivo diffusion chamber method, Calcif. Tissue Int., 36:83, 1984" and "Characterization of cells with high alkaline phosphates activity derived from human bone and marrow; preliminary assessment of their osteogenicity, Bone, 5:313-319, 1985" are cited for their work on stromal cells (MSCs) and their osteogenic potential.
• Goshima, et al. (1989): "The Origin of Bone Formed in Composite Grafts of Porous Calcium Phosphate Ceramic and Marrow Cells' (1989) Submitted." This work, also by one of the current inventors, indicated that bone formation in ceramic grafts is a biphasic phenomenon.
• Co-pending U.S. patent application: US5197985 explicitly states that the "process for isolating, purifying, and greatly replicating the marrow-derived mesenchymal cells in culture, i.e. in vitro" was the subject of a co-pending U.S. patent application.

Obviousness of Claims for Bone Formation and Skeletal Defect Repair (Claims 1-9, 15)

Combination of Prior Art: Beresford (1989) + Ohgushi et al. (1989) + the concept of culturally expanding MSCs.

Motivation for Combination:

1. Known Osteogenic Potential of Marrow Cells: Beresford (1989) and Ashton et al. (1984, 1985) established that "prestromal" cells or fibroblastic colony-forming cells (now known as mesenchymal stem cells or MSCs) within bone marrow possess the potential to differentiate into bone-forming cells (osteogenic potential).
2. Known Use of Porous Ceramics for Bone Repair with Marrow: Ohgushi et al. (1989), co-authored by inventor Caplan, demonstrated that a "composite graft with porous ceramic" combined with "rat marrow" could successfully fill segmental bone defects with new bone. This clearly taught the use of porous ceramic carriers with marrow-derived cells for in vivo bone regeneration. Goshima et al. (1989) further supported this.
3. Motivation to Enhance and Standardize Cell Delivery: The inventors of US5197985 explicitly state that the objective of isolating, purifying, and culturally expanding marrow-derived mesenchymal cells is "to greatly increase the number of potentially reparative cells and to utilize these cells to redirect and/or reinforce the body's normal reparative capacity." Furthermore, Bab et al. (1988) showed limitations in bone formation from whole marrow in older donors.

A PHOSITA, aware of the osteogenic potential of MSCs (Beresford, Ashton et al.) and the effectiveness of porous ceramic carriers with whole marrow for bone repair (Ohgushi et al., Goshima et al.), would have been highly motivated to combine the isolated and culturally expanded MSCs with these known porous ceramic carriers. The motivation would be to overcome the limitations of using unpurified, unexpanded whole marrow (such as low MSC frequency and age-dependent variability observed by Bab et al.) and to achieve more robust, predictable, and efficient bone formation. The methodology for obtaining culturally expanded MSCs is explicitly detailed within US5197985 (e.g., using specific media for selective adherence, mechanical dissociation, Percoll gradients, trypsin/EDTA or EGTA for detachment), indicating it was either known through their own co-pending work or made available by the disclosure itself.

The choice of specific porous ceramic composition (e.g., "about 60% hydroxyapatite and about 40% tricalcium phosphate" as in claims 3, 5, 7, 15) would also have been obvious. Hydroxyapatite and tricalcium phosphate were well-known biocompatible and osteoconductive ceramic materials routinely considered for bone regeneration applications.

Therefore, the methods for inducing bone formation and repairing skeletal defects using culturally expanded MSCs on a porous ceramic carrier, as claimed in US5197985, would likely be rendered obvious by combining the teachings of Beresford (1989) and Ohgushi et al. (1989) with the motivation to improve cell density and consistency, achievable through the disclosed cell expansion techniques.

Obviousness of Claims for Cartilage Formation and Articular Cartilage Repair (Claims 10-14)

Combination of Prior Art: Beresford (1989) + culturally expanded MSCs (as described in US5197985) + general knowledge of chondrocyte differentiation and biocompatible carriers.

Motivation for Combination:

1. Known Chondrogenic Potential of Marrow Cells: Beresford (1989) taught that marrow "prestromal" cells have the capacity to differentiate into cartilage cells. US5197985 itself states that MSCs "possess the potential to differentiate into cells which produce various types of connective tissue, such as osteoblasts and chondrocytes".
2. Known Importance of Round Cell Morphology for Chondrogenesis: The patent explicitly acknowledges that a PHOSITA would know that "round cell shape" is "important to induction of chondrocyte differentiation."
3. Known Biocompatible Carriers: Collagen and fibrin were well-known biocompatible materials commonly used in tissue engineering for their low antigenicity and pliability.

A PHOSITA, aware of the chondrogenic potential of MSCs (Beresford), and the acknowledged importance of maintaining a round cell morphology for driving chondrocyte differentiation, would have been motivated to select a biocompatible carrier (such as collagen or fibrin) known to facilitate this morphology, to promote the differentiation of culturally expanded MSCs into cartilage for repairing articular cartilage defects. The problem (damaged articular cartilage not healing) and the general approach of using stem cells were apparent. The selection of specific carrier materials like collagen or fibrin, known for their biocompatibility, pliability, and ability to influence cell shape, would be a matter of routine design choice to achieve the desired chondrogenic differentiation. The patent itself describes this as a "projected" treatment in Example 2B, which further suggests that it was a logical extension of existing knowledge rather than an unexpected discovery.

Therefore, the methods for inducing cartilage formation and repairing damaged articular cartilage using culturally expanded MSCs on a carrier promoting round cell morphology, as claimed in US5197985, would likely be rendered obvious by combining the teachings of Beresford (1989) with the detailed cell expansion methods described in the patent, and the general knowledge regarding chondrocyte differentiation and the properties of common biocompatible scaffold materials.