Engineered Fascia ECM for Soft Tissue Repair Title of Presentation Arial Regular 38pt Date 15pts Author Name 15pts Author Title 15pts Cleveland Clinic Kathleen Derwin, PhD October 30, 2008
Rotator Cuff Tendon Tears Intra-articular, two or more tendons Do not heal naturally Secondary to degenerative tendon changes Muscle atrophy and fatty infiltration Difficult to mobilize and high mechanical loads required for repair A significant percentage (50% or more) re-tear Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 2
Critical Need No tissue repair strategy currently exists for large tendon and muscle defects that is strong, large, has good suture retention and provides enhanced wound healing. Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 3
Repair Augmentation with Tissue Engineered Scaffold Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 4
Extracellular matrix (ECM) patches for tendon repair FDA approved for rotator cuff repair augmentation Rationale natural, three-dimensional and mechanically robust scaffold that may have ability off-load the repair a chemically and structurally instructive environment for host cells leading to integration and the formation of bridging tissues Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 5
Commercially available ECM devices Product Name Restore CuffPatch GraftJacket TissueMend Zimmer Collagen Repair Patch OrthADAPT Bioimplant AlloPatch Tissue Type SIS SIS (crosslinked) Dermis Dermis (fetal) Dermis (crosslinked) Pericardium (crosslinked) Fascia Lata Source Porcine Porcine Human Bovine Porcine Equine Human Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 6
Uniaxial Tensile Properties (Aurora et al, JSES, 2007) 50 50 Stress (MPa) 40 30 20 Stress (MPa) 40 30 20 10 0 Infraspinatus Tendon (Canine) AlloPatch GraftJacket (Fascia) (Dermis) TissueMend (Dermis) Restore (SIS) CuffPatch (SIS) 0 0.2 0.4 0.6 0.8 10 Grip-to-Grip Strain 0 0 0.2 0.4 0.6 0.8 1 Grip-to-Grip Strain Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 7
Tensor Fascia Lata Atlas of Human Anatomy by Carl Toldt, M.D., 1919. Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 8
Regional variation, biophysical properties, effects of processing of fascia (Derwin et al, JBMR, 2008) Fascia is mechanically, chemically and ultrastructurally similar to tendon. Acellularization processing did not significantly change the mechanical properties or GAG content Superficial of fascia Layer ECM Deep fascicles Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 9
Suture Retention Properties Barber et al, Arthroscopy, 2006 Derwin, Unpublished Data Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 10
Suture Retention Fascia is stiff and strong but it has poor suture retention Suture retention properties are as important as the material and structural properties of the device Aligned fascicles Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 11
Fascia ECM We like fascia for rotator cuff repair because mechanical stiffness and strength are needed and fascia has mechanical properties similar to tendon Engineered improvements: Fiber reinforcement to increase suture retention properties Reduce inflammation associated with allograft transplantation and processing Delivery of anabolic molecules to enhance integration to host tissues and/or tendon-bone healing Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 12
Fascia ECM We like fascia for rotator cuff repair because mechanical stiffness and strength are needed and fascia has mechanical properties similar to tendon Engineered improvements: Fiber reinforcement to increase suture retention properties Reduce inflammation associated with allograft transplantation and processing Delivery of anabolic molecules to enhance integration to host tissues and/or tendon-bone healing Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 13
Reinforcement variables investigated Fiber types PLA braids PGA braids Silk Configurations Cross-hatch Peripheral Mesh Single layer or laminates Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 14
Reinforcement variables investigated Fiber types PLA braids PGA braids Silk Configurations Cross-hatch Peripheral Mesh Single layer or laminates Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 15
Standard Suture Retention Test 2 x 5 cm strip One simple suture, #2 Fiberwire 12.5 mm/min to failure Outcomes Suture Retention Load Construct Stiffness Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 16
Standard Suture Retention Test Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 17
Standard Suture Retention Test Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 18
Perfect Clamping vs. Suture Retention Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 19
What test models construct loading in vivo? Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 20
Tension with Side Constraint 4 x 4 cm patch Simple suture, 1cm increments, #2 Fiberwire 10N side static constraint Uniaxial dynamic tension Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 21
Tension with Side Constraint-- Failure Pre-cycle 5-15N, 10x 30 mm/min to failure Outcomes Suture Retention Load Construct Stiffness Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 22
Tension with Side Constraint-- Failure Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 23
Tension with Side Constraint-- Failure Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 24
Tension with Side Constraint-- Fatigue 5-150N, 0.25 Hz 5000 cycles Outcomes (vs. cycle number) Construct deformation Construct stiffness Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 25
Tension with Side Constraint-- Fatigue Native fascia fails on first cycle so no cyclic fatigue data are generated Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 26
Tension with Side Constraint-- Fatigue Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 27
Summary Fascia ECM has chemical, structural and material properties similar to tendon but poor suture retention Fiber reinforcement improves the suture retention and stiffness of native fascia ECM by 10-fold Suture retention load of reinforced fascia patch (~350 N) exceeds highest predicted in vivo loads (~150-250 N) On first cycle of loading, the reinforced fascia ECM construct is an order of magnitude more compliant than with perfect (clamp) fixation Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 28
Ongoing/Future Work Polymer fiber degradation/loss of suture retention Alternate fiber types for reinforcement Bone fixation Test efficacy for rotator cuff repair Human Cadaver Model Canine Injury and Repair Model Clinical Trials Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 29
Ongoing/Future Work Polymer fiber degradation/loss of suture retention Alternate fiber types for reinforcement Bone fixation Test efficacy for rotator cuff repair Human Cadaver Model Canine Injury and Repair Model Clinical Trials Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 30
Human Cadaver Model Primary Repair Primary Repair + Scaffold Mechanical Testing Set-up Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 31
Broad Significance No tissue repair technology currently exists for large tendon and muscle defects that is natural, strong, large, has good suture retention and provides enhanced wound healing. Engineered fascia lata potentially offers all of these advantages with indication for: Augmentation of large tendon defects Ligament repair Extension of rotational muscle transfers Grafting lacerated muscles Periosteal coverage and wound healing Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 32
Acknowledgements Musculoskeletal Transplant Foundation (Edison, NJ) Concordia Fiber (Coventry, RI) Funding Ohio Biomedical Research and Technology Transfer Partnership Cleveland State University AFIRM Amit Aurora, Joseph Iannotti, Jesse McCarron Engineered fascia ECM for soft tissue repair l 23-Oct-08 l 33