Cartilage Regeneration with Tunable Inflammation Resistance

Period of Performance: 09/15/2017 - 05/31/2018


Phase 2 SBIR

Recipient Firm

Cytex Therapeutics Inc.
Durham, NC 27705
Principal Investigator


Abstract The repair of large cartilage lesions, which are contraindicated for currently available first- line tissue regeneration techniques, remains a significant clinical problem with few good treatment options. Previous work at Cytex has focused on the development of a 3D microwoven textile scaffold for cartilage repair, designed to function immediately after implantation while encouraging cell ingrowth, proliferation, and subsequent tissue development. When combined with mesenchymal stem cells (MSCs), we have demonstrated the ability to form biomechanically functional implants for the treatment of large cartilage lesions, including resurfacing the femoral condyles. However, for a stem cell- based cartilage implant to be successful in the osteoarthritic (OA) joint, it must withstand the the high degree of inflammation and the associated catabolic and degenerative environment found in diseased joints. The objective of this proposal is to add an anti- inflammatory capability to our construct in order to protect the engineered tissues from the hostile joint environment. We will transduce the MSCs in our implant with an inflammation- responsive promoter that will drive the expression of Interleukin 1 (IL- 1) receptor antagonist (IL- 1Ra) or soluble tumor necrosis factor (TNF) receptor (sTNFR), natural modulators that inhibit the inflammatory signaling of IL- 1 and TNF?, respectively. The resulting cartilage construct will provide inflammation resistance only when inflammatory signaling is present, thus eliminating the need for exogenous injections and the potential side effects associated with long- term administration of anti- cytokine therapy. In Aim 1, we will examine our lentiviral transduction conditions in an effort to minimize the risk of genetic side effects in the MSCs. The resulting cartilage constructs will also be analyzed to ensure that they contain no active lentiviral particles, which could be released upon implantation, thereby validating the clinical safety of the genetic approach. In Aim 2, we will use our biomimetic cartilage implants to resurface the medial femoral condyle in a goat model of unicompartmental osteoarthritis. Our current tissue engineered implant will be compared to implants in which the MSC population has been transduced to express anti- cytokine therapeutics in either a constant, or an inflammation- responsive manner. All animals will be evaluated at 3, 6, 9, and 12- month time points following repair through clinically relevant measures of function, pain, and imaging using X- Rays and MRI. At sacrifice, joint tissues will be assessed histologically and biomechanically to quantify degradative changes and OA progression. Serum, synovial fluid, and synovium will be analyzed for biomarkers of osteoarthritis, as well as for adverse inflammatory reactions and to test for wear debris in the joint. Additionally, all major organ systems will be examined to assess the safety of implanting transduced cells and utilizing localized anti- cytokine therapy. Ultimately, this proposal will develop a cartilage resurfacing product that is not only be able to function mechanically within the joint but will also protect itself and surrounding tissues from inflammatory signaling, and hopefully prevent further OA progression.