WO2008070186A2 - Dispositif d'échafaudage pour favoriser une fixation tendon sur os - Google Patents

Dispositif d'échafaudage pour favoriser une fixation tendon sur os Download PDF

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Publication number
WO2008070186A2
WO2008070186A2 PCT/US2007/025127 US2007025127W WO2008070186A2 WO 2008070186 A2 WO2008070186 A2 WO 2008070186A2 US 2007025127 W US2007025127 W US 2007025127W WO 2008070186 A2 WO2008070186 A2 WO 2008070186A2
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Prior art keywords
graft collar
graft
collar
mesh
tendon
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PCT/US2007/025127
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English (en)
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WO2008070186A3 (fr
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Helen H. Lu
Jeffrey Spalazzi
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The Trustees Of Columbia University In The City Of New York
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Publication of WO2008070186A2 publication Critical patent/WO2008070186A2/fr
Publication of WO2008070186A3 publication Critical patent/WO2008070186A3/fr
Priority to US12/455,765 priority Critical patent/US20100047309A1/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/50—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
    • A61L27/52—Hydrogels or hydrocolloids
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/08—Muscles; Tendons; Ligaments
    • A61F2/0811—Fixation devices for tendons or ligaments
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/36—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix
    • A61L27/38—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix containing added animal cells
    • A61L27/3804—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix containing added animal cells characterised by specific cells or progenitors thereof, e.g. fibroblasts, connective tissue cells, kidney cells
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/36—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix
    • A61L27/38—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix containing added animal cells
    • A61L27/3839—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix containing added animal cells characterised by the site of application in the body
    • A61L27/3843—Connective tissue
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/40—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material
    • A61L27/44—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having a macromolecular matrix
    • A61L27/446—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having a macromolecular matrix with other specific inorganic fillers other than those covered by A61L27/443 or A61L27/46
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/40—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material
    • A61L27/44—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having a macromolecular matrix
    • A61L27/46—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having a macromolecular matrix with phosphorus-containing inorganic fillers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/50—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
    • A61L27/54—Biologically active materials, e.g. therapeutic substances
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/08—Muscles; Tendons; Ligaments
    • A61F2/0811—Fixation devices for tendons or ligaments
    • A61F2002/0847—Mode of fixation of anchor to tendon or ligament
    • A61F2002/087—Anchor integrated into tendons, e.g. bone blocks, integrated rings
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
    • A61L2300/40—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a specific therapeutic activity or mode of action
    • A61L2300/412—Tissue-regenerating or healing or proliferative agents
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
    • A61L2300/40—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a specific therapeutic activity or mode of action
    • A61L2300/412—Tissue-regenerating or healing or proliferative agents
    • A61L2300/414—Growth factors
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
    • A61L2300/60—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a special physical form
    • A61L2300/602—Type of release, e.g. controlled, sustained, slow
    • A61L2300/604—Biodegradation

Definitions

  • This application relates to musculoskeletal tissue engineering, and more particularly, to techniques for tendon-to-bone fixation.
  • a graft collar for fixing tendon to bone in a subject is discussed below.
  • Some exemplary embodiments which include a soft tissue- bone interface are discussed.
  • ACL human anterior cruciate ligament
  • the ACL consists of a band of regularly oriented, dense connective tissue that spans the junction between the femur and tibia. It participates in knee motion control and acts as a joint stabilizer, serving as the primary restraint to anterior tibial translation.
  • the natural ACL-bone interface consists of three regions: ligament, fibrocartilage (non-mineralized and mineralized) and bone.
  • the natural ligament to bone interface is arranged linearly from ligament to fibrocartilage and to bone. The transition results in varying cellular, chemical, and mechanical properties across the interface, and acts to minimize stress concentrations from soft tissue to bone.
  • the ACL is the most often injured ligament of the knee. Due to its inherently poor healing potential and limited vascularization, ACL ruptures do not heal effectively upon injury, and surgical intervention is typically needed to restore normal function to the knee.
  • a primary cause for the high failure rate is the lack of consistent graft integration with the subchondral bone within bone tunnels.
  • the site of graft contact in femoral or tibial tunnels represents the weakest point mechanically in the early post-operative healing period. Therefore, success of ACL reconstructive surgery depends heavily on the extent of graft integration with bone.
  • ACL reconstruction based on autografts often results in loss of functional strength from an initial implantation time, followed by a gradual increase in strength that does not typically reach the original magnitude.
  • long term performance of autogenous ligament substitutes is dependent on a variety of factors, including structural and material properties of the graft, initial graft tension, intrarticular position of the graft, as well as fixation of the graft. These grafts typically do not achieve normal restoration of ACL morphology and knee stability.
  • Fixation devices include, for example, staples, screw and washer, press fit EndoButton® devices, and interference screws.
  • EndoButton® devices or Mitek® Anchor devices are utilized for fixation of femoral insertions. Staples, interference screws, or interference screws combined with washers can be used to fix the graft to the tibial region.
  • interference screws have emerged as a standard device for graft fixation.
  • the interference screw about 9 mm in diameter and at least 20 mm in length, is used routinely to secure tendon to bone and bone to bone in ligament reconstruction.
  • the knee is flexed and the screw is inserted from the para-patellar incision into the tibial socket, and the tibial screw is inserted just underneath the joint surface.
  • the femoral tunnel screw is inserted. This procedure has been reported to result in stiffness and fixation strength levels which are adequate for daily activities and progressive rehabilitation programs.
  • Two insertion zones can be found in the ACL, one at the femoral end and another located at the tibial attachment site.
  • the ACL can attach to mineralized tissue through insertion of collagen fibrils, and there exists a gradual transition from soft tissue to bone.
  • the femoral attachment area in the human ACL was measured to be 113 ⁇ 27 mm 2 and 136 ⁇ 33 mm 2 for the tibia insertion. With the exception of the mode of collagen insertion into the subchondral bone, the transition from ACL to bone is histologically similar for the femoral and tibial insertion sites.
  • the insertion site is comprised of four different zones: ligament, non-mineralized fibrocartilage, mineralized fibrocartilage, and bone.
  • the first zone which is the ligament proper, is composed of solitary, spindle-shaped fibroblasts aligned in rows, and embedded in parallel collagen fibril bundles of 70-150 ⁇ m in diameter.
  • type I collagen makes up the extracellular matrix
  • type III collagen which are small reticular fibers, are located between the collagen I fibril bundles.
  • the second zone which is fibro-cartilaginous in nature, is composed of ovoid-shaped chondrocyte-like cells. The cells do not lie solitarily, but are aligned in rows of 3-15 cells per row.
  • Collagen fibril bundles are not strictly parallel and much larger than those found in zone 1.
  • Type II collagen is now found within the pericellular matrix of the chondrocytes, with the matrix still made up predominantly of type I collagen. This zone is primarily avascular, and the primary sulfated proteoglycan is aggrecan. The next zone is mineralized fibrocartilage . In this zone, chondrocytes appear more circular and hypertrophic, surrounded by larger pericellular matrix distal from the ACL.
  • Type X collagen a specific marker for hypertrophic chondrocytes and subsequent mineralization, is detected and found only within this zone. The interface between mineralized fibrocartilage and subjacent bone is characterized by deep inter-digitations .
  • bone-to-bone integration with the aid of interference screws is the primary mechanism facilitating graft fixation.
  • Several groups have examined the process of tendon-to-bone healing.
  • tendon-to-bone healing with and without interference fixation does not result in the complete re- establishment of the normal transition zones of the native ACL-bone insertions.
  • This inability to fully reproduce these structurally and functionally different regions at the junction between graft and bone is detrimental to the ability of the graft to transmit mechanical stress across the graft proper and leads to sites of stress concentration at the junction between soft tissue and bone.
  • Zonal variations from soft to hard tissue at the interface facilitate a gradual change in stiffness and can prevent build up of stress concentrations at the attachment sites.
  • the insertion zone is dominated by non-mineralized and mineralized fibrocartilage, which are tissues adept at transmitting compressive loads. Mechanical factors may be responsible for the development and maintenance of the fibrocartilagenous zone found at many of the interfaces between soft tissue and bone. The fibrocartilage zone with its expected gradual increase in stiffness appears less prone to failure.
  • Gao et al. determined that the thickness of the calcified fibrocartilage zone was 0.22 ⁇ 0.7 mm and that this was not statistically different from the tibial insertion zone. While the ligament proper is primarily subjected to tensile and torsional loads, the load profile and stress distribution at the insertion zone is more complex.
  • Matyas et al. (1995) combined histomorphometry with a finite element model (FEM) to correlate tissue phenotype with stress state at the medial collateral ligament (MCL) femoral insertion zone.
  • FEM finite element model
  • the FEM model predicted that when the MCL is under tension, the MCL midsubstance is subjected to tension and the highest principal compressive stress is found at the interface between ligament and bone.
  • Calcium phosphates have been shown to modulate cell morphology, proliferation and differentiation. Calcium ions can serve as a substrate for Ca 2+ -binding proteins, and modulate the function of cytoskeleton proteins involved in cell shape maintenance.
  • Gregiore et al. (1987) examined human gingival fibroblasts and osteoblasts and reported that these cells underwent changes in morphology, cellular activity, and proliferation as a function of hydroxyapatite particle sizes.
  • Culture distribution varied from a homogenous confluent monolayer to dense, asymmetric, and multilayers as particle size varied from less than 5 ⁇ m to greater than 50 ⁇ m, and proliferation changes correlated with hydroxyapatite particles size.
  • Chondrocytes are also dependent on both calcium and phosphates for their function and matrix mineralization.
  • Wuthier et al. (1993) reported that matrix vesicles in fibrocartilage consist of calcium-acidic phospholipids- phosphate complex, which are formed from actively acquired calcium ions and an elevated cytosolic phosphate concentration.
  • a scaffold apparatus for promoting tendon-to-bone fixation can include (or take on the form of) a graft collar.
  • a graft collar comprises a sheet of collagen mesh.
  • a graft collar comprises a sheet of polymer-fiber mesh.
  • This application further provides a graft collar for fixing tendon to bone in a subject, wherein the graft collar comprises, according to yet another embodiment, (a) a first region comprising a hydrogel and (b) a second region adjoining the first region and comprising a collagen mesh.
  • a graft collar for fixing tendon to bone in a subject comprises (a) a first region comprising a hydrogel and (b) a second region adjoining the first region and comprising a polymer-fiber mesh.
  • This application further provides a graft collar for fixing tendon to bone in a subject, wherein said graft collar comprises a sheet of mesh comprising fibers aligned substantially perpendicular in relation to a longitudinal axis of said tendon, wherein said mesh applies compression to the graft.
  • This application further provides a graft collar for fixing tendon to bone in a subject, wherein said graft collar comprises a sheet of mesh comprising fibers aligned substantially parallel in relation to a longitudinal axis of said tendon, wherein said mesh applies lateral tension to the graft.
  • Figure IA A schematic diagram of a graft collar, wherein the graft collar comprises a sheet of biopolymer mesh or polymer-fiber mesh, according to one embodiment.
  • Figure IB A schematic diagram of a graft collar, wherein the graft collar comprises 2 regions wherein (i) region 1 comprises a biopolymer mesh or a polymer-fiber mesh and (ii) region 2 comprises a biopolymer mesh or a polymer-fiber mesh and a hydrogel, according to one embodiment .
  • Figure 2 A schematic diagram of a graft collar, wherein the graft collar comprises 2 regions wherein (i) region A comprises a biopolymer mesh or a polymer-fiber mesh and (ii) region B comprises a biopolymer mesh or a polymer- fiber mesh and a hydrogel, according to one embodiment. As indicated, additional substances can be added to regions A and B.
  • Figure 3A Posterior view of an intact bovine anterior cruciate ligament (ACL) connecting the femur to the tibia (left).
  • Figure 3B Environmental scanning electron microscope (ESEM) image of transition from ligament (L) to fibrocartilage (FC) to bone (B) at the ACL insertion (upper right).
  • Figure 3C Histological micrograph of similar ACL to bone interface additionally showing mineralized fibrocartilage (MFC) zone (lower right).
  • ESEM Environmental scanning electron microscope
  • Figures 4A and 4B show Bovine tibial-femoral joint after ACL and insertion site extraction (right) , ACL and insertion sites after excision.
  • Figure 5A shows FTIR Spectra of BG immersed in SBF for up to 7 days. Presence of an amorphous Ca-P layer at 1 day, and of a crystalline layer at 3 days.
  • Figure 5B SEM image of Ca-P nodules on BG surface (3 days in SBF) . Nodules are ⁇ 1 ⁇ m in size initially, and grew as immersion continued (15,00Ox).
  • Figure 5C EDXA spectrum of BG surfaces immersed in SBF for 3 days. The relative Ca/P ratio is « 1.67.
  • Figures 6A and 6B show environmental SEM images of Bovine ACL insertion Site (1 and 2), including a cross section of the ACL-femur insertion site, ACL fiber (L) left, fibrocartilage region (FC) middle, and sectioned bone (B) right (Figure 6A: 250X; Figure 6B: 500X) .
  • Figure 7A SEM of the cross section of the femoral insertion zone, 100OX;
  • Figure 7B EDAX of the femoral insertion zone.
  • the peak intensities of Ca, P are higher compared to those in ligament region.
  • Figure 8 shows apparent modulus versus indentation X- position across sample.
  • Figures 9A and 9B show X-Ray CT scans of discs made of poly-lactide-co-glycolide (PLAGA) 50:50 and bioactive glass (BG) submerged in SBF for 0 days ( Figure 9A) and 28 days; Figure 9B shows the formation of Ca-P over time.
  • PLAGA poly-lactide-co-glycolide
  • BG bioactive glass
  • Figure 1OA SEM image
  • Figure 1OB EDAX of PLAGA-BG immersed in SBF for 14 days.
  • Figure 11 shows osteoblast grown on PLAGA-BG, 3 weeks.
  • Figure 12 shows higher type I collagen type synthesis on PLAGA-BG.
  • Figure 13A ALZ stain, ACL fibroblasts 14 days, 2Ox
  • Figure 13B ALZ stain, interface, ACL 14 days, 2Ox
  • Figure 13C ALZ stain, osteoblasts, ACL 14 days, 2Ox.
  • Figure 14A ALP stain, ACL fibroblasts, 7 days, 32x
  • Figure 14B ALP+DAPI stain, co-culture, 7 days, 32x
  • Figure 14C ALP stain, osteoblasts, 7 days, 32x.
  • Figures 15A-15F show images of multiphase scaffold (Figures 15A-15C) and blow-ups of respective sections ( Figures 15D-15F) .
  • Figures 16A-16C show multiphasic scaffold for co-culture of ligament fibroblasts and osteoblasts;
  • Figure 16A and Figure 16B images of a sample scaffold;
  • Figure 16C schematic of scaffold design depicting the three layers.
  • Figures 17A-17D show Micromass co-culture samples after 14 days.
  • Figure 17A H&E stain
  • Figure 17B Alcian blue
  • Figure 17C Type I collagen (green)
  • Figure 17D Type II collagen (green) + Nucleic stain (red) .
  • Figures 18A and 18B show RT-PCR gel for day 7 micromass samples.
  • Figure 18A Type X collagen expression.
  • Figure 18B Type II collagen expression.
  • Figures 19A and 19B show SEM image of cellular attachment to PLAGA-BG scaffold after 30 min; Figure 19A: chondrocyte control (2000X) ; Figure 19B: co-culture (1500X) .
  • Figures 20A-20C show Cellular attachment to PLAGA-BG scaffold;
  • Figure 2OA chondrocyte control, day 1 (500X) ;
  • Figure 2OB co-culture, day 1 (500X) .
  • Figure 2OC co- culture, day 7 (750X) .
  • Fig. 21-1 shows a table of porosimetry data, including intrusion volume, porosity, and pore diameter data, in another set of experiments.
  • Figs. 21-2A through 21-2C show fluorescence microscopy images (day 28, xlO) for Phases A through C, respectively.
  • Figs. 21-3A and 21-3B are images showing extracellular matrix production for Phases B and C, respectively.
  • Fig. 22-1 shows a schematic of the experimental design, in another set of experiments, for in vitro evaluations of human osteoblasts and fibroblasts co-cultured on multi-phased scaffolds.
  • Fig. 22-2 shows a graph which demonstrates cell proliferation in Phases A, B, and C during 35 days of human hamstring tendon fibroblast and osteoblast co- culture on multiphased scaffolds.
  • Fig. 23-1 schematically shows a method for producing multi-phasic scaffolds, in another set of experiments.
  • Ethicon PLAGA mesh is cut into small pieces and inserted into a mold.
  • F compression force
  • H heating
  • the mesh segments are sintered into a mesh scaffold, which is removed from the mold.
  • PLAGA microspheres are inserted into the mold, sintered, then removed as a second scaffold.
  • the same process is performed for the PLAGA-BG microspheres.
  • Phases A and B are joined by solvent evaporation, then all three scaffolds are inserted into the mold and sintered together, forming the final multi-phasic scaffold.
  • Fig. 23-2 shows a schematic of a co-culture experimental design.
  • Fig. 23-3 shows a table summarizing mercury porosimetry data.
  • Figs. 23-4A and 23-4B show graphically scaffold phase thicknesses and diameters, in the experiments of Fig. 23- 1 through Fig. 23-3.
  • Fig. 23-5 shows graphically a comparison of microsphere initial mass and final mass after undergoing a sintering process .
  • Fig. 24-1 shows a table illustrating the compositions of polymer solutions tested, in another set of experiments.
  • Fig. 24-2 shows a table illustrating drum rotational velocity (rpm) and surface velocity (m/s) for each gear.
  • Figs. 25-3A and 25-3D show SEMs of electrospun meshes spun at:
  • Fig. 25-4A and 25-4B show scanning electron microscopy (SEM) images of another embodiment of multi-phased scaffold, with 85:15 PLAGA electrospun mesh joined with PLAGA: BG composite microspheres.
  • Fig. 26 schematically shows one exemplary embodiment of multi-phased scaffold as a hamstring tendon graft collar which can be implemented during ACL reconstruction surgery to assist with hamstring tendon-to-bone healing.
  • Fig. 27A shows an exemplary embodiment of a graft collar (A)_comprising a mesh, wherein the fibers of the mesh are aligned substantially parallel to a longitudinal axis of the tendon (B) .
  • Figure 27B shows an exemplary embodiment of a graft collar (C) comprising a mesh, wherein the fibers of the mesh are aligned substantially perpendicular to a longitudinal axis of the tendon (D) .
  • Fig. 28 Characterization of Nanofiber Mesh Contraction.
  • Fig. 29 Compression of Graft Collar Scaffold with Nanofiber Mesh.
  • Fig. 30 Compression of Tendon Graft with Nanofiber Mesh.
  • Fig. 31 Compression of Tendon Graft with Graft Collar Scaffold and Nanofiber Mesh.
  • Fig. 32 Effects of Compression on Tendon Cellularity and Matrix Composition.
  • Fig. 33 Effects of Compression on the Expression of Fibrocartilage-Related Markers. Scaffold-induced compression of the tendon graft resulted in significant up-regulation of type II collagen, aggrecan, and TGF- ⁇ 3 after 24 hours (*p ⁇ 0.05) .
  • Fig. 34 Effects of wrapping tendon with a PLGA electrospun mesh wherein fibers are either perpendicular or parallel to the longitudinal axis of the tendon.
  • aligned fibers shall mean groups of fibers which are oriented along the same directional axis. Examples of aligned fibers include, but are not limited to, groups of parallel fibers.
  • allogenic in regards to a biopolymer mesh, shall mean a biopolymer mesh derived from a material originating from the same species as the subject receiving the biopolymer mesh.
  • bioactive shall include a quality of a material such that the material has an osteointegrative potential, or in other words the ability to bond with bone. Generally, materials that are bioactive develop an adherent interface with tissues that resist substantial mechanical forces.
  • biomimetic shall mean a resemblance of a synthesized material to a substance that occurs naturally in a human body and which is not rejected by (e.g., does not cause an adverse reaction in) the human body.
  • biopolymer mesh shall mean any material derived from a biological source. Examples of a biopolymer mesh include, but are limited to, collagen, chitosan, silk and alginate.
  • BMP bone morphogenetic protein
  • BMSC bone marrow-derived stem cells
  • chondrocyte shall mean a differentiated cell responsible for secretion of extracellular matrix of cartilage.
  • fibroblast shall mean a cell of connective tissue, mesodermally derived, that secretes proteins and molecular collagen including fibrillar procollagen, fibronectin and collagenase, from which an extracellular fibrillar matrix of connective tissue may be formed.
  • GDF growth differentiation factor
  • matrix shall mean a three-dimensional structure fabricated from biomaterials .
  • the biomaterials can be biologically-derived or synthetic.
  • hydrogel shall mean any colloid in which the particles are in the external or dispersion phase and water is in the internal or dispersed phase.
  • a chondrocyte-embedded agarose hydrogel may be used in some instances.
  • the hydrogel may be formed from hyaluronic acid, chitosan, alginate, collagen, glycosaminoglycan and polyethylene glycol
  • lyophilized in regards to a graft collar, shall mean a graft collar that has been rapidly frozen and dehydrated.
  • osteoblast shall mean a bone-forming cell that is derived from mesenchymal osteoprognitor cells and forms an osseous matrix in which it becomes enclosed as an osteocyte.
  • the term is also used broadly to encompass osteoblast-like, and related, cells, such as osteocytes and osteoclasts.
  • osteointegrative shall mean ability to chemically bond to bone.
  • PDGF blood pressure regulator
  • photopolymerized shall mean using light (e.g. visible or ultraviolet light) to convert a liquid monomer or macromer into a hydrogel by free radical polymerization.
  • polymer shall mean a chemical compound or mixture of compounds formed by polymerization and including repeating structural units. Polymers may be constructed in multiple forms and compositions or combinations of compositions.
  • porosity shall mean the ratio of the volume of interstices of a material to a volume of a mass of the material.
  • PTHrP parathyroid hormone-related protein
  • sinter or “sintering” shall mean densification of a particulate polymer compact involving a removal of pores between particles (which may be accompanied by equivalent shrinkage) combined with coalescence and strong bonding between adjacent particles.
  • the particles may include particles of varying size and composition, or a combination of sizes and compositions.
  • sintering a polymer would involve heating the polymer above the glass transition temperature, wherein the polymer chains rearrange and link together to form sintering necks.
  • TGF shall mean transforming growth factor
  • VEGF vascular endothelial growth factor
  • xenogenic in regards to a biopolymer mesh, shall mean a biopolymer mesh derived from a raaterial originating from a species other than that of the subject receiving the biopolymer mesh.
  • Apparatuses for promoting tendon-to-bone fixation can include a graft collar for fixing tendon to bone in a subject.
  • the graft collar may be adapted for hamstring tendon-to-bone healing.
  • a graft collar comprising a sheet of biopolymer mesh is provided for fixing tendon to bone in a subject.
  • the biopolymer mesh may comprise aligned fibers.
  • the contraction of the fibers of the biopolymer mesh can be used to exert lateral tension or shear on the tendon (i.e., when fibers are aligned substantially parallel in relation to a longitudinal axis of the tendon) or vertical compression on the graft (i.e., when fibers are aligned substantially perpendicular in relation to a longitudinal axis of the tendon) .
  • biopolymer meshes include, but are not limited to, meshes derived from at least one of collagen, chitosan, silk and alginate.
  • the biopolymer mesh can also be allogenic or xenogenic.
  • the graft collar may optionally be sutured around a tendon graft.
  • the subject may be a mammal. In another embodiment, the mammal is a human. In a preferred embodiment, the graft collar promotes integration of the tendon graft to bone.
  • the graft collar may optionally include at least one of the following substances: anti-infectives, antibiotics, bisphosphonate, hormones, analgesics, anti-inflammatory agents, growth factors, angiogenic factors, chemotherapeutic agents, anti-rejection agents, and RGD peptides.
  • the growth factors are selected from the group consisting of TGFs, BMPs, IGFs, PTHrP, GDFs, VEGFs and PDGFs.
  • the TGF is TGF- ⁇ .
  • the TGF- ⁇ is TGF- ⁇ 3.
  • the BMP is BMP-2.
  • the GDF is GDF-5 or GDF-7.
  • the graft collar may include one or more of the following types of cells: chondrocytes, osteoblasts, osteoblast-like cells and stem cells.
  • the graft collar includes at least one of the following: osteogenic agents, osteogenic materials, osteoinductive agents, osteoinductive materials, osteoconductive agents, osteoconductive materials and chemical factors.
  • the graft collar promotes regeneration of an interfacial region between tendon and bone.
  • the graft collar may optionally be lyophilized.
  • the graft collar is biodegradable.
  • the graft collar is osteointegrative .
  • a graft collar for fixing tendon to bone in a subject comprises a sheet of polymer-fiber mesh.
  • the polymer-fiber mesh preferably comprises aligned fibers.
  • the graft collar may optionally be sutured around a tendon graft.
  • the contraction of the fibers of the polymer-fiber mesh can be used to exert lateral tension or shear on the graft
  • the subject may be a mammal.
  • the mammal is a human.
  • the graft collar promotes integration of the tendon graft to bone.
  • the graft collar may optionally include at least one of the following substances: anti-infectives, antibiotics, bisphosphonate, hormones, analgesics, anti-inflammatory agents, growth factors, angiogenic factors, chemotherapeutic agents, anti-rejection agents, and RGD peptides.
  • the growth factors are selected from the group consisting of TGFs, BMPs, IGFs,
  • the TGF is TGF- ⁇ .
  • the TGF- ⁇ is TGF- ⁇ 3.
  • the BMP is BMP-2.
  • the GDF is GDF-5 or GDF-7.
  • the graft collar may optionally include one or more of the following types of cells: chondrocytes, osteoblasts, osteoblast-like cells and stem cells.
  • the graft collar includes at least one of the following: osteogenic agents, osteogenic materials, osteoinductive agents, osteoinductive materials, osteoconductive agents, osteoconductive materials and chemical factors.
  • the polymer-fiber mesh can be selected from the group comprising aliphatic polyesters, poly (amino acids), copoly (ether-esters) , polyalkylenes oxalates, polyamides, poly (iminocarbonates) , polyorthoesters, polyoxaesters, polyamidoesters, poly ( ⁇ -caprolactone) s, polyanhydrides, polyarylates, polyphosphazenes, polyhydroxyalkanoates, polysaccharides, and biopolymers, and a blend of two or more of the preceding polymers.
  • the polymer-fiber mesh comprises at least one of the poly (lactide-co-glycolide) , poly (lactide) and poly (glycolide) .
  • the graft collar promotes regeneration of an interfacial region between tendon and bone.
  • graft collar may optionally be lyophilized.
  • the graft collar is biodegradable.
  • the graft collar is osteointegrative .
  • a graft collar for fixing tendon to bone in a subject comprises (a) a first region comprising a biopolymer mesh and hydrogel and (b) a second region adjoining the first region and comprising a biopolymer mesh.
  • the subject may be a mammal.
  • the mammal is a human.
  • the first region preferably supports the growth and maintenance of an interfacial zone between tendon and bone, and the second region supports the growth and maintenance of bone tissue.
  • the graft collar can include at least one of the following substances: anti-infectives, antibiotics, bisphosphonate, hormones, analgesics, anti-inflammatory agents, growth factors, angiogenic factors, chemotherapeutic agents, anti-rejections agents, and RGD peptides.
  • the hydrogel is photopolymerized, thermoset or chemically cross-linked.
  • the hydrogel is polyethylene glycol.
  • the biopolymer mesh comprises aligned fibers .
  • the contraction of the fibers of the biopolymer mesh can be used to exert lateral tension or shear on the graft (i.e., when fibers are aligned substantially parallel in relation to a longitudinal axis of the tendon) or vertical compression on the graft (i.e., when fibers are aligned substantially perpendicular in relation to a longitudinal axis of the tendon) .
  • the first region may optionally contain TGF.
  • the TGF is TGF- ⁇ .
  • the TGF- ⁇ is TGF- ⁇ 3.
  • the first region may optionally contain PTHrp or GDF.
  • the GDF is GDF-5 or GDF-7.
  • the first region contains chondrocytes.
  • the chondrocytes are BMSC-derived.
  • the first region contains stem cells.
  • the stem cells are BMSCs.
  • biopolymer meshes include, but are not limited to, meshes is derived from at least one of collagen, chitosan, silk and alginate. In another embodiment, the biopolymer mesh is allogenic or xenogenic.
  • the second region contains at least one of the following growth factors: BMP, IGF, PTHrP, GDF, VEGF and PDGF.
  • BMP is BMP-2.
  • GDF is GDF-5 or GDF-7.
  • the second region includes osteoblasts and/or osteoblast-like cells.
  • the osteoblasts and/or osteoblast like cells are BMSC-derived.
  • the second region can include at least one of the following: osteogenic agents, osteogenic materials, osteoinductive agents, osteoinductive materials, osteoconductive agents, osteoconductive materials and chemical factors.
  • the second region contains nanoparticles of calcium phosphate.
  • the calcium phosphate is selected from the group comprising tricalcium phosphate, hydroxyapatite and a combination thereof.
  • the second region contains nanoparticles of bioglass .
  • the graft collar is preferably biodegradable. In another embodiment, the graft collar is osteointegrative.
  • a graft collar for fixing tendon to bone in a subject comprises (a) a first region comprising a polymer-fiber mesh and hydrogel and (b) a second region adjoining the first region and comprising a polymer-fiber mesh.
  • the subject can be a mammal.
  • the mammal is a human.
  • the first region preferably supports the growth and maintenance of an interfacial zone between tendon and bone, and the second region supports the growth and maintenance of bone tissue.
  • the graft collar can include at least one of the following substances: anti-infectives, antibiotics, bisphophonate, hormones, analgesics, anti-inflammatory agents, growth factors, angiogenic ' 'Xfactors, chemotherapeutic agents, anti-rejections agents, and RGD peptides.
  • the hydrogel is photopolymerized, thermoset or chemically cross-linked.
  • the hydrogel is polyethylene glycol.
  • the polymer-fiber mesh comprises aligned fibers.
  • the first region may optionally contain TGF.
  • the TGF is TGF- ⁇ . In another embodiment, the TGF is TGF- ⁇ .
  • TGF- ⁇ is TGF- ⁇ 3.
  • the first region may optionally contain PTHrp or GDF.
  • the GDF is GDF-5 or GDF-7.
  • the first region contains chondrocytes.
  • the chondrocytes are BMSC-derived.
  • the first region contains stem cells.
  • the stem cells are BMSCs.
  • the second region contains at least one of the following growth factors: BMP, IGF, PTHrP,
  • the BMP is BMP-2.
  • the GDF is GDF-5 or GDF-7.
  • the second region includes osteoblasts and/or osteoblast-like cells.
  • the osteoblasts and/or osteoblast like cells are BMSC-derived.
  • the second region can include at least one of the following: osteogenic agents, osteogenic materials, osteoinductive agents, osteoinductive materials, osteoconductive agents, osteoconductive materials and chemical factors.
  • the second region contains nanoparticles of calcium phosphate.
  • the calcium phosphate is selected from the group comprising tricalcium phosphate, hydroxyapatite and a combination thereof.
  • the second region contains nanoparticles of bioglass.
  • the polymer-fiber mesh in the second region can be selected from the group comprising aliphatic polyesters, poly (amino acids), copoly (ether-esters) , polyalkylenes oxalates, polyamides, poly (iminocarbonates) , polyorthoesters, polyoxaesters, polyamidoesters, poly( ⁇ - caprolactone) s, polyanhydrides, polyarylates, polyphosphazenes, polyhydroxyalkanoates, polysaccharides, and biopolymers, and a blend of two or more of the preceding polymers.
  • the polymer- fiber mesh comprises at least one of the poly (lactide-co- glycolide) , poly (lactide) and poly (glycolide) .
  • the contraction of the fibers of the polymer- fiber mesh can be used to exert lateral tension or shear on the graft (i.e., when fibers are aligned substantially parallel in relation to a longitudinal axis of the tendon) or vertical compression on the graft (i.e., when fibers are aligned substantially perpendicular in relation to a longitudinal axis of the tendon) .
  • the graft collar is preferably biodegradable. In another embodiment, the graft collar is osteointegrative .
  • a normal and functional interface may be engineered between the ligament and bone.
  • This interface was developed from the co- culture of osteoblasts and ligament fibroblasts on a multi-phased scaffold system with a gradient of structural and functional properties mimicking those of the native insertion zones to result in the formation of a fibrocartilage-like interfacial zone on the scaffold. Variations in mineral content from the ligament proper to the subchondral bone were examined to identify design parameters significant in the development of the multi- phased scaffold. Mineral content (Ca-P distribution, Ca/P ratio) across the tissue-bone interface was characterized.
  • a multi-phased scaffold with a biomimetic compositional variation of Ca-P was developed and effects of osteoblast-ligament fibroblast co-culture on the development of interfacial zone specific markers (proteoglycan, types II & X collagen) on the scaffold were examined.
  • the insertion sites of bovine ACL to bone were examined by SEM. Pre-skinned bovine tibial- femoral joints were obtained. The intact ACL and attached insertion sites were excised with a scalpel and transferred to 60mm tissue culturing dishes filled with Dulbecco's Modified Eagle Medium (DMEM) (see Figures 4A and 4B) . After isolation, the samples were fixed in neutral formalin overnight, and imaged by environmental SEM (FEI Quanta Environmental SEM) at an incident energy of 15 keV. ACL attachment to the femur exhibited an abrupt insertion of the collagen bundle into the cartilage/subchondral bone matrix.
  • DMEM Dulbecco's Modified Eagle Medium
  • Bovine ACL to bone were examined by scanning electron microscopy (SEM) .
  • Bovine tibial- femoral joints were obtained.
  • the intact ACL and attached insertion sites were excised with a scalpel and transferred to 60 mm tissue culturing dishes filled with Dulbecco' s Modified Eagle Medium (DMEM). After isolation, the samples were fixed in neutral formalin overnight, and imaged by environmental SEM (FEI Quanta Environmental SEM) at 15 keV.
  • DMEM Dulbecco' s Modified Eagle Medium
  • ACL attachment to the femur exhibited an abrupt insertion of the collagen bundle into subchondral bone.
  • a cross section was imaged (see Figures 6A and 6B) , three distinct zones at the insertion site were evident: ligament (L), fibrocartilage (FC), and subchondral bone (B) . Sharpey fiber insertion into the fibrocartilage (see Figure 6A) was observed.
  • the bovine interface region spans proximally 600 ⁇ m. Examination of the interface using energy dispersive X-ray analysis (EDAX, FEI Company) enable the mineralized and non-mineralized FC zones to be distinguished. A zonal difference in Ca and P content was measured between the ligament proper and the ACL-femoral insertion (see Table I) .
  • the scaffold system developed for the experiments was based on a 3-D composite scaffold of ceramic and biodegradable polymers.
  • a composite system has been developed by combining poly-lactide-co-glycolide (PLAGA) 50:50 and bioactive glass (BG) to engineer a degradable, three-dimensional composite (PLAGA-BG) scaffold with improved mechanical properties.
  • PHAGA poly-lactide-co-glycolide
  • BG bioactive glass
  • This composite was selected as the bony phase of the multi-phased scaffold as it has unique properties suitable as a bone graft.
  • a significant feature of the composite was that it was osteointegrative, i.e., able to bond to bone tissue. No such calcium phosphate layer was detected on PLAGA alone, and currently, osteointegration was deemed a significant factor in facilitating the chemical fixation of a biomaterial to bone tissue.
  • a second feature of the scaffold was that the addition of bioactive glass granules to the PLAGA matrix results in a structure with a higher compressive modulus than PLAGA alone. The compressive properties of the composite approach those of trabecular bone.
  • the PLAGA-BG lends greater functionality in vivo compared to the PLAGA matrix alone.
  • the combination of the two phases serves to neutralize both the acidic byproducts produced during polymer degradation and the alkalinity due to the formation of the calcium phosphate layer.
  • the composite supports the growth and differentiation of human osteoblast-like cells in vitro.
  • the polymer-bioactive glass composite developed for the experiments was a novel, three-dimensional, polymer- bioactive biodegradable and osteointegrative glass composite scaffold.
  • the morphology, porosity and mechanical properties of the PLAGA-BG construct have been characterized.
  • BG particle reinforcement of the PLAGA structure resulted in an approximately two-fold increase in compressive modulus (p ⁇ 0.05).
  • PLAGA-BG scaffold formed a surface Ca-P layer when immersed in an electrolyte solution (see Figure 10A), and a surface Ca-P layer was formed. No such layer was detected on PLAGA controls.
  • EDXA spectra confirmed the presence of Ca and P (see Figure 10B) on the surface. The Ca, P peaks were not evident in the spectra of PLAGA controls.
  • Porosity, pore diameter, and mechanical properties of the scaffold may be variable as a function of microsphere diameter and BG content.
  • the growth and differentiation of human osteoblast-like cells on the PLAGA-BG scaffolds were also examined.
  • the composite supported osteoblast- like morphology and stained positive for alkaline phosphatase .
  • the porous, interconnected network of the scaffold was maintained after 3 weeks of culture (see Figure 11) .
  • bovine osteoblast and fibroblast co- culture were examined.
  • the cells were isolated using primary explant culture.
  • the co-culture was established by first dividing the surfaces of each well in a multi-well plate into three parallel sections using sterile agarose inserts.
  • ACL cells and osteoblasts were seeded on the left and right surfaces respectively, with the middle section left empty. Cells were seeded at 50,000 cells/section and left to attach for 30 minutes prior to rinsing with PBS.
  • the agarose inserts were removed at day 7, and cell migration into the interface was monitored. Control groups were fibroblasts alone and osteoblasts alone.
  • both ACL fibroblasts and osteoblasts proliferated and expanded beyond the initial seeding areas. These cells continued to grow into the interfacial zone, and a contiguous, confluent culture was observed. All three cultures expressed type I collagen over time. The co-culture group expressed type II collagen at day 14, while the control fibroblast did not.
  • Type X collagen was not expressed in these cultures, likely due to the low concentration of b-GP used.
  • ACL fibroblasts on the scaffold another type of multi-phased scaffold was fabricated using a PLAGA mesh (Ethicon, NJ) and two layers of PLAGA-BG microspheres. The layers were sintered in three stages in a Teflon mold. First the mesh was cut into small pieces and sintered in the mold for more than 20 hours at 55 0 C. A layer of PLAGA-BG microspheres with diameter of 425-500 ⁇ m was then added to the mold. This layer was sintered for more than 20 hours at 75°C. The final layer consisted of PLAGA-BG microspheres with diameter greater than 300 ⁇ m. The scaffolds and three distinct regions were readily observed (see Figures 16A-16C) .
  • FTIR Fourier transform infrared spectroscopy
  • SEM SEM
  • EDXA energy dispersive x-ray analysis
  • FTIR provides information on the degree of crystallinity (amorphous vs. crystalline) of the Ca-P layer formed (see Figure 4) as well as the functional groups present on BG surface (carbonated Ca-P layer versus non-carbonated, protein adsorption, etc.).
  • FTIR is much more surface sensitive than X-ray diffraction in detecting the Ca-P crystalline structures when the surface layer is only several microns in thickness.
  • SEM combined with EDXA is a powerful tool in relating elemental composition to specific surface morphology and distributions (see Figures 5B and 5C) .
  • FTIR, SEM, and EDXA are complimentary techniques which together provide quantitative data on the crystallinity, composition of and functional groups pertaining to the Ca-P layer.
  • chondrocytes may have dedifferentiated due to co-culturing with osteoblasts.
  • the expression of type I collagen was observed to be distributed mainly on the top surface of the co-cultured mass (Figure 17C), where osteoblasts were located.
  • Type I was also found at the primarily osteoblastic monolayer surrounding the micromass (see Figure 17C, left) .
  • No type I collagen expression was observed in the chondrocyte-dominated center and bottom surface of the micromass.
  • High expression of type II collagen was observed within the micromass (see Figure 17D) .
  • Electron microscopy examination of the ACL-bone interface revealed insertion zone including three different regions: ligament, fibrocartilage-like zone, and bone.
  • Co-culture of osteoblasts and ligament fibroblasts on 2-D and 3-D scaffolds resulted in changes in cell morphology and phenotype.
  • Type X collagen an interfacial zone marker, was expressed during co-culture.
  • Multi-phased scaffold with layered morphology and inhomogenous properties were designed and fabricated.
  • FTIR, SEM and EDXA are complimentary techniques which collectively provided qualitative and quantitative information on the Ca-P layer and composition of the calcium phosphate surface.
  • the degree of graft integration is a significant factor governing clinical success and it is believed that interface regeneration significantly improves the long term outcome.
  • the approach of this set of experiments was to regenerate the ACL-bone interface through biomimetic scaffold design and the co-culture of osteoblasts and fibroblasts.
  • the interface exhibits varying cellular, chemical, and mechanical properties across the tissue zones, which can be explored as scaffold design parameters.
  • This study describes the design and testing of a multi-phased, continuous scaffold with controlled heterogeneity for the formation of multiple tissues.
  • the continuous scaffold consists of three phases: Phase A for soft tissue, Phase C for bone, and Phase B for interface development. Each phase was designed with optimal composition and geometry suitable for the tissue type to be regenerated. Fibroblasts were seeded on Phase A and osteoblasts were seeded on Phase C, and the interactions of osteoblasts and fibroblasts (ACL and hamstring tendon) during co-cultures on the scaffolds were examined in vitro.
  • Phases A, B and C consist of poly (lactide-co-glycolide) (PLAGA, 10: 90) woven mesh, PLAGA (85:15) microspheres, and PLAGA (85: 15) /Bioactive Glass (45S5,BG) composite microspheres, respectively.
  • Bovine and human osteoblasts (bOB and hOB) , and bovine ACL fibroblasts (bFB) and human hamstring tendon fibroblasts (hFB) were obtained through explant culture.
  • bOB and bFB (5xlO 5 cells each/scaffold) were co-cultured on the scaffold, and cell viability, attachment, migration and growth were evaluated by electron and fluorescence microscopy.
  • the bOB were pre- labeled with CM-DiI, and both cell types were labeled with calcein AM (Molecular Probes) prior to imaging. Matrix production and mineralization were determined by histology. After ascertaining cell viability on the scaffolds, a more extensive experiment using hOB and hFB was conducted in which cell proliferation and differentiation and above analyses were investigated. The mechanical properties of the seeded scaffolds were also measured as a function of culture time.
  • fibroblasts and osteoblasts were localized primarily at the two ends of the scaffolds after initial seeding, with few cells found in Phase B. After 28 days, both cell types migrated into Phase B (Fig. 21-2B), and extensive cell growth was observed in Phases A and C (Figs. 21-2A and 21-2C) .
  • this novel scaffold is capable of simultaneously supporting the growth of multiple cell types and can be used as a model system to regenerate the soft tissue to bone interface.
  • Fig. 22-2 Cell proliferation in Phases A, B, and C during 35 days of human hamstring tendon fibroblast and osteoblast co- culture on multiphased scaffolds is shown in Fig. 22-2. A general trend of increasing cell number was observed in each phase over time. Data demonstrates that all three phases of the scaffold support cellular viability and proliferation. A higher number of cells were seeded on phase A due to its inherently larger surface area compared to phase C.
  • the cell seeded scaffolds degraded slower and better maintained their structural integrity over time.
  • the yield strength of the acellular scaffold decreased over 35 days, while the seeded scaffolds maintained its yield strength.
  • Phase A was formed from polyglactin 10:90 PLGA mesh sheets (Vicryl VKML, Ethicon) . Mesh sheets were cut into small segments (approximately 5 mm x 5 mm) and inserted into cylindrical molds (7.44 mm diameter). Molds were heated to 150°C for 20 hours to sinter the segments together to form a cylindrical mesh scaffold.
  • Phase B consisted of 100% 85:15- poly (DL-lactide- co-glycolide) (PLAGA, Alkermes Medisorb, M w « 123.6 kDa) microspheres formed by a water/oil/water emulsion.
  • PLAGA poly (DL-lactide- co-glycolide)
  • PVA surfactant solution Sigma Chemicals, St. Louis, MO
  • phase C To form the PLAGA microsphere phase, -0.075 g microspheres were inserted into the same molds as used previously, and sintered at 55°C for 5 hours.
  • the last phase (Phase C) consisted of composite microspheres formed from an 80:20 ratio of PLAGA and 45S5 bioactive glass (BG, MO-SCI Corporation, Rolla, MD) . Again, microspheres were formed by emulsion, except with 0.25 g bioactive glass suspended in a solution of 1 g PLAGA in 10 mL methylene chloride. Microspheres (28-30 mg/scaffold) were sintered in the same molds at 55 0 C for five hours.
  • Phases A and B were joined by methylene chloride solvent evaporation, and then sintered to Phase C for 10 hours at 55°C in the same molds. Subsequently, scaffolds were sterilized with ethylene oxide. Final scaffold dimensions are detailed in Figs. 23-4A and 23-4B.
  • Human osteoblast-like cells and hamstring tendon fibroblasts were obtained from explant culture of tissue isolated from humerus trabecular bone and hamstring tendon respectively. Trabecular bone was rinsed with PBS, then cultured in Dulbecco' s Modified Eagle's Medium (DMEM, Mediatech, Herndon, VA, USA) supplemented with 10% fetal bovine serum, 1% non essential amino acids, and 1% penicillin/streptomycin (Mediatech, Herndon, Virginia) , and incubated at 37°C in a 5% CO2 incubator to allow for cell migration. Hamstring tendon obtained from excess tissue utilized for hamstring tendon ACL reconstruction autografts was minced and cultured in similarly supplemented DMEM. The first migrations of cells were discarded to obtain a more uniform cell distribution. Second migration, passage 2 osteoblast-like cells and second and third migration, passage 5 hamstring tendon fibroblasts were utilized for the co-culture experiment.
  • DMEM Dulbecco'
  • Hamstring tendon fibroblasts were seeded at a density of 250,000 cells/scaffold in a volume of 40.7 ⁇ L/scaffold on Phase A (Fig. 23-2) . After allowing the fibroblasts to attach to the scaffolds for 20 minutes, the scaffolds were rotated upside down so that Phase C faced upwards. Subsequently, 75,000 osteoblast-like cells were seeded per scaffold in a volume of 12.5 ⁇ L. After allowing the osteoblasts to attach to the scaffold for 20 minutes, the scaffolds were covered with DMEM supplemented with 10% FBS, 1% NEAA, and 1% penicillin/streptomycin, and incubated at 37 0 C and 5% CO 2 .
  • Ascorbic acid at a concentration of 20 ⁇ g/mL was added beginning at day 7. Media was exchanged every two days. Scaffolds were cultured in 6-well plates and covered with 7 mL of supplemented media per scaffold to minimize pH fluctuations due to rapid poly (glycolic acid) degradation.
  • Extracellular matrix production and mineralization were determined via histology at day 35. Scaffolds were rinsed two times with room temperature PBS. The scaffolds were then covered with 10% neutral buffered formalin and stored at 4 degrees C. Samples were plastic embedded using a modification of a procedure developed by Erben. The scaffolds were first suspended in 2% agarose (low gelling temperature, cell culture grade, Sigma, St.
  • the scaffold sections were stained with either hematoxylin and eosin, von Kossa or Picrosirius Red stains and imaged with light microscopy.
  • PLAGA-BG microspheres for Phase C generally experience a 2.1 ⁇ 1.4 % loss in mass, while the PLAGA microspheres for Phase B suffer a loss of 4.0 ⁇ 1.8 % (Fig. 23-5).
  • Composite microspheres are generally more statically charged than the PLAGA microspheres; however, the stainless steel mold, used more often for the composite microspheres, dissipates charge buildup more readily than the PTFE mold, which is used more often for the PLAGA microspheres, possibly explaining why there is a significant loss for Phase B (p ⁇ 0.05). Mesh for Phase A is not susceptible to this loss.
  • Compressive modulus and yield strength were obtained for seeded and acellular control scaffolds at days 0, 7, 21, and 35 of culture. A rapid decrease in compressive modulus was observed following day 0, possibly due to rapid initial polymer degradation. By day 35, the seeded scaffolds exhibited a greater compressive modulus (Fig. 23-6A) and yield strength (Fig. 23-6B), possibly due to cellular extracellular matrix and mineralization compensating loss of scaffold strength due to polymer degradation.
  • this novel scaffold is capable of simultaneously supporting the growth of multiple cell types and can be used as a model system to regenerate the soft tissue to bone interface.
  • the objective of the set of experiments was to incorporate electrospun PLAGA meshes into the multi- phased scaffold design, substituting the Ethicon mesh phase, and allowing the entire scaffold to be made in- house .
  • Electrospinning short for electrostatic spinning, is a relatively new term that describes a principle first th discovered in the first half of the 20 century (see, for example, U.S. Patents Nos. 1,975,504, 2,160,962, 2,187,306, 2,323,025 and 2,349,950 to Formhals, the entire contents of which are incorporated herein by reference) .
  • Electrostatic spinning involves the fabrication of fibers by applying a high electric potential to a polymer solution. The material to be electrospun, or dissolved into a solution in the case of polymers, is loaded into a syringe or spoon, and a high potential is applied between the solution and a grounded substrate.
  • the electrostatic force applied to the polymer solution overcomes surface tension, distorting the solution droplet into a Taylor cone from which a jet of solution is ejected toward the grounded plate.
  • the jet splays into randomly oriented fibers, assuming that the solution has a high cohesive strength, linked to polymer chain molecular weight, to prevent droplets from forming instead of fibers in a process known as electrospraying.
  • These fibers have diameters ranging from nanometer scale to greater than 1 ⁇ m and are deposited onto the grounded substrate or onto objects inserted into the electric field forming a non-woven mesh. Mesh characteristics can be customized by altering electrospinning parameters.
  • fiber diameter and morphology can be altered, including the formation of beads along the fibers, by controlling applied voltage and polymer solution surface tension and viscosity.
  • fiber orientation can be controlled by rotating the grounded substrate .
  • Management of fiber diameter allows surface area to be controlled, and polymers with different degradation rates can be combined in various ratios to control fiber degradation, both of which are significant in drug delivery applications.
  • controlling the orientation of fiber deposition grants a degree of control over cell attachment and migration.
  • the ability to electrospin fiber meshes onto non-metal objects placed in the electric field enables the fabrication of multiphasic scaffold systems.
  • a solvent trap was not used since it is not designed to fit with this geometry and a prior trial using the solvent trap with another geometry resulted in poor results, possibly because water from the solvent trap seal interacted with the polymer solution. Additional trials can use a solvent trap to obtain consistent and reliable values for viscosity. For the present study, averages were taken of the viscosity measurements taken at strain rates tested after the equipment had equilibrated. As a result, there are standard deviations for the viscosity measurements even with an n of 1.
  • the surface velocity of the rotating drum was seen to increase with increased pulley positions from gear 1 to gear 4 (see the table shown in Fig. 24-2) .
  • the degree of fiber alignment increased with increasing drum velocity, as seen in the SEMs of each mesh (see Figs. 25-3A through 25-3D) .
  • PEO polyethylene glycol
  • ethanol ethanol
  • surface tension of the polymer solution acts to form spheres during the electrospinning process. By reducing the solution surface tension, the formation of spheres is less favorable and straighter fibers result.
  • Fong et al. also determined that the addition of ethanol increased the viscosity of the PE0:water solutions, which also favors the formation of straight fibers, and results in increased fiber diameter.
  • Deitzel et al. also have demonstrated a relationship between PEO: water solution viscosity and fiber diameter, with fiber diameter increasing with increasing viscosity according to a power law.
  • a relationship between solution viscosity and concentration of polymer can be determined in order to understand how PLAGA: N,W-DMF viscosity affects fiber diameter and morphology.
  • the effect of solution viscosity on fiber diameter and morphology can be determined by spinning the various solutions and examining the resulting meshes by SEM. Other variables can affect the fiber parameters.
  • the surface tensions of the polymer solutions also change in addition to the viscosity. Therefore, in addition to testing the viscosities of each solution, the surface tension of each solution are measured. It is desirable to keep all variables constant except for viscosity in order to truly determine the effect of solution viscosity on fiber characteristics. However, the interrelation of many of the electrospinning parameters complicates the process.
  • a PLAGA mesh was electrospun directly onto a microsphere scaffold. This is one way to incorporate the mesh.
  • the scaffolds can be secured to the drum and aligned fibers electrospin directly onto the scaffolds.
  • aligned fiber meshes can simply be spun separately, and then later sintered to the microsphere scaffolds.
  • aligned fiber meshes can be electrospun onto aluminum foil, then wrapped around a rod with multiple mesh sheets sintered together to obtain a hollow cylinder of aligned fibers.
  • Fig. 25-4A and 25-4B show scanning electron microscopy (SEM) images of another embodiment of multi-phased scaffold, with 85:15 PLAGA electrospun mesh joined with PLAGA: BG composite microspheres.
  • ACL Anterior Cruciate Ligament
  • Patellar tendon grafts were isolated from neonatal bovine tibiofemoral joints (1-7 days old) obtained from a local abattoir (Green Village Packing, Green Village, NJ) . Briefly, the joints were first cleaned in an antimicrobial bath. Under antiseptic conditions, midline longitudinal incisions were made through the subcutaneous fascia to expose the patellar tendon. The paratenon was removed, and the patellar tendon dissected from the underlying fat pad. Sharp incisions were made through the patellar tendon at the patellar and tibial insertions, and the insertions were completely removed from the graft.
  • Aligned nanofiber meshes (Fig. 28A,B) were fabricated by electrospinning 13 .
  • a viscous polymer solution consisting of 35% poly (DL-lactic-co-glycolic acid) 85:15 (PLGA, I. V. 0.70 dL/g, Lakeshore Biomaterials, Birmingham, AL), 55% N, N-dimethylformamide (Sigma, St. Louis, MO), and 10% ethanol (Commercial Alcohol, Inc., Toronto, Ontario) was loaded into a syringe fitted with an 18-gauge needle (Becton Dickinson, Franklin Lakes, NJ) .
  • Aligned fibers 82 were obtained using an aluminum drum with an outer diameter of 10.2 cm rotating with a surface velocity of 20 m/s.
  • Fiber morphology, diameter and alignment of the as-fabricated mesh samples were analyzed using scanning electron microscopy (SEM) . Briefly, the samples were sputter-coated with gold (LVC-76, Plasma Sciences, Lorton, VA) and subsequently imaged (JSM 5600LV, JEOL, Tokyo, Japan) at an accelerating voltage of 5 kV.
  • a tendon graft collar based on a sintered microsphere scaffold was fabricated following published methods 38 ' ' 69 .
  • the microspheres were formed following the methods of Lu et al. 38 , where the polymer was first dissolved in dichloromethane (Acros Organics, Morris Plains, NJ) and then BG particles were added (20 wt%) .
  • the suspension was poured into a 1% solution of polyvinyl alcohol (Sigma, St. Louis, MO) to form the microspheres.
  • the microspheres were subsequently sintered at 70 0 C for 5 hours in a custom mold to form cylindrical scaffolds with an outer diameter of 0.7 cm and an inner diameter of 0.3 cm.
  • the potential of utilizing nanofiber mesh contraction to directly apply compression to the tendon graft was evaluated over time. Briefly, the aligned electrospun meshes were cut into 10 cm x 2 cm strips, with fiber alignment oriented along the long axis of the mesh. The patellar tendon graft was bisected along its long axis, and one half of the tendon was wrapped with the nanofiber mesh while the other half served as the unloaded control
  • Fig. 30A The samples were cultured in DMEM supplemented with 1% non-essential amino acids, 1% antibiotics, and 0.1% antifungal (all from Mediatech) and 10% FBS (Atlanta Biologicals) . At days 5 and 14, the effects of compression on tissue morphology and cellularity were characterized by histology 68 .
  • the samples were rinsed with phosphate buffered saline (PBS, Sigma), fixed with 10% neutral buffered formalin (Fisher Scientic and Sigma) and embedded in paraffin (Fisher Scientific, Pittsburgh, PA) . The samples were then cut into 7- ⁇ m thick sections and stained with hematoxylin and eosin (H&E) .
  • PBS phosphate buffered saline
  • H&E hematoxylin and eosin
  • Sample fluorescence was measured using a microplate reader (Tecan, Research Triangle Park, NC) , with excitation and emission wavelengths set at 485 and 535 nm, respectively.
  • the total number of cells in the sample was calculated using the conversion factor of 8 pg DNA/cell 40 .
  • GAG glycosaminoglycan
  • DMMB colorimetric 1, 9-dimethylmethylene blue
  • DMMB complexes was determined using a plate reader at 540 and 595 nm and correlated to a standard prepared with chondroitin-6-sulfate.
  • fibrocartilage markers such as collagen I, II, aggrecan, and Transforming Growth Factor- Beta 3 (TGF- ⁇ 3) was determined at day 1 using reverse- transcription polymerase chain reaction (RT-PCR) . Briefly, after removing the graft collar and nanofiber mesh, total RNA of the tendon graft was obtained using the Trizol extraction method (Invitrogen, Carlsbad, CA) . The isolated RNA was reverse-transcribed into cDNA using the Superscript III First-Strand Synthesis System (Invitrogen, Carlsbad, CA) and the cDNA product was amplified using recombinant Platinum Tag DNA polymerase (Invitrogen) . GAPDH was used as the housekeeping gene, and expression band intensities were measured (ImageJ) and normalized against GAPDH.
  • RT-PCR reverse- transcription polymerase chain reaction
  • Results are presented in the form of mean ⁇ standard deviation, with n equal to the number of samples analyzed.
  • Two-way analysis of variance (ANOVA) was first performed to assess if differences exist among the means. Fisher's LSD post-hoc test was subsequently performed for all pair-wise comparisons and statistical significance was attained at p ⁇ 0.05.
  • ANOVA analysis of variance
  • Fisher's LSD post-hoc test was subsequently performed for all pair-wise comparisons and statistical significance was attained at p ⁇ 0.05.
  • All statistical analyses were performed using the JMP statistical software package (SAS Institute, Cavy, NC) .
  • the nanofiber mesh exhibited a high degree of alignment with an average fiber diameter of 0.9 ⁇ 0.4 ⁇ m (Fig. 28A) .
  • Anisotropic mesh contractile behavior was observed in the mesh, with significantly higher contraction found in the direction of nanofiber alignment.
  • the mesh contracted over 57% along the aligned fiber direction (y-axis) by 2 hours, with less than 13% reduction in the x-axis (Fig. 28B).
  • Mesh contraction continued over time, exhibiting over 70% contraction in the y-axis and 20% in the x-axis by 24 hours and stabilizing thereafter, with no significant differences found between the 24- and 72-hour groups.
  • the tendon graft was compressed by a complex of the graft collar scaffold and nanofiber mesh. It was observed that at 24 hours post-compression (Fig. 31B, top) , the tendon graft matrix organization was distinct from that of the unloaded control, with increased matrix density and less of the characteristic crimp of the tendon. After 14 days of compression by the scaffold+mesh complex, it was found that the matrix remodeling visible 24 hours following the onset of loading was maintained over time (Fig. 31B, bottom). In contrast, the control tendon retained its characteristic crimp, with evident disruption of the matrix ultrastructure.
  • fibrocartilage markers such as types I and II collagen, aggrecan and TGF- ⁇ 3 were evaluated after compression with the graft collar scaffold and nanofiber mesh. As shown in Fig. 33, after 24 hours of compression, gene expression of type II collagen, aggrecan and TGF- ⁇ 3 were all up-regulated in the loaded group when compared to non-compressed tendons (Fig. 33), with significant differences found in aggrecan and TGF- ⁇ 3 expression.
  • the long term goal is to achieve biological fixation by engineering a functional and anatomical fibrocartilage interface on biological and synthetic soft tissue grafts used in orthopaedic repair 39 .
  • the current study focuses on the design and evaluation of a novel graft collar scaffold system capable of applying mechanical loading and inducing fibrocartilage formation on tendon grafts.
  • scaffold-mediated compression of a patellar tendon graft was evaluated over time, focusing on the effects of loading on tendon matrix organization and cell response. It was found that the complex of the nanofiber mesh and graft collar was able to apply a physiological range of compressive loading to tendon grafts.
  • scaffold-mediated compression promoted matrix remodeling, maintained graft glycosaminoglycan content and, interestingly, induced gene expression for fibrocartilage markers, including type II collagen, aggrecan, and TGF- ⁇ 3.
  • fibrocartilage markers including type II collagen, aggrecan, and Transforming Growth Factor- ⁇ 3 (TGF- ⁇ 3) .
  • TGF- ⁇ 3 Transforming Growth Factor- ⁇ 3
  • fibrocartilage in tendons is largely comprised of types I and II collagen, as well as proteoglycans 5 ' ' 15; 32; 47 .
  • compressive loading of fibrocartilaginous regions of tendons has been reported to increase the synthesis of Transforming Growth Factor- ⁇ l (TGF- ⁇ l) 58 and large proteoglycans, as well as enhancing aggrecan gene expression 15 ' ' 32 .
  • the polyester co-polymer utilized in this study has a high D,L-lactide content (85%) and is non-crystalline, thus the above mechanism may explain the high degree of contraction observed.
  • fiber alignment-related scaffold anisotropy may be controlled to modulate mesh contraction, and consequently, the magnitude and direction of compressive loading on the graft may be controlled by customizing the degree of fiber alignment.
  • Future studies will focus on elucidating the mechanism of mesh contraction as well as exploring methods to control this process for mechanical stimulation. This is the first study to incorporate mechanical loading into scaffold design and to demonstrate the potential of using this mechano-active scaffold system to induce fibrocartilage formation on soft tissue grafts.
  • the mesh- collar system is intended to be applied clinically as a degradable graft collar, and will be used to initiate and direct regeneration of an anatomical fibrocartilage interface at the insertion of tendon-based ACL reconstruction grafts.
  • the innovative scaffold system described here can also apply physiologic mechanical stimulation crucial for directing cellular function and tissue remodeling.
  • the graft would be inserted through the collars immediately prior to implantation, and compression of the graft and subsequent fibrocartilage formation would occur in vivo.
  • Allografts which do not contain viable cells necessary for remodeling the tendon matrix, would need to be repopulated with fibroblasts or stem cells delivered either from the scaffold in vitro prior to graft implantation. It has been reported that mesenchymal stem cell (MSC) -seeded type I collagen sponges inserted into excised sheep patellar tendons and loaded using an ex vivo wrap-around system results in an up-regulation of chondrogenic markers such as Sox9 and Fos 34 . A similar response by a cell-populated tendon allograft is anticipated following scaffold-mediated compressive loading.
  • MSC mesenchymal stem cell
  • the mesh-scaffold system is based on degradable poly- ⁇ -hydroxyester polymers, thus it is expected that the mechano-active scaffold will be replaced by newly formed tissue after a functional fibrocartilage interface has been formed on the graft. Future studies will evaluate the potential of coupling the mechano-active scaffold with ACL reconstruction grafts using in vivo models.
  • Lu, HH, Tang, A, Oh, SC, Spalazzi,JP, and Dionisio,K Compositional effects on the formation of a calcium phosphate layer and the response of osteoblast-like cells on polymer- bioactive glass composites.
  • Nanofiber alignment in biodegradable polymer scaffold directs attachment and matrix elaboration of human rotator cuff fibroblasts.
  • Nawata,K, Minamizaki, T, Yamashita,Y, and Teshima,R Development of the attachment zones in the rat anterior cruciate ligament: changes in the distributions of proliferating cells and fibrillar collagens during postnatal growth. J. Orthop. Res. 20:1339-1344, 2002.
  • Niyibizi,C, Sagarrigo, VC, Gibson, G, and Kavalkovich, K Identification and immunolocalization of type X collagen at the ligament-bone interface. Biochem. Biophys . Res Commun. 222:584-589, 1996.
  • Rodeo, SA Studies of tendon-to-bone healing: exploring ways to improve graft fixation following anterior cruciate ligament reconstruction. Jornal of Bone and Joint
  • Yoshiya,S, Nagano, M, Kurosaka,M, Muratsu,H, and Mizuno,K Graft healing in the bone tunnel in anterior cruciate ligament reconstruction. Clin.Orthop. 278-286, 2000.
  • the objective of this experiment was to determine the effect of wrapping tendon with a PLGA electrospun mesh wherein the fibers of the mesh were either perpendicular or parallel to the longitudinal axis of the tendon.
  • the control group exhibited a 13.3 ⁇ 6.4 percentage change in tendon diameter and a -6.2 ⁇ 5.2 percentage change in tendon length.
  • the perpendicular fiber group exhibited a -40.0 ⁇ 63.6 percentage change in tendon diameter and a 12.9 ⁇ 2.2 percentage change in tendon length.
  • the parallel fiber group exhibited a 5.6 ⁇ 6.7 percentage change in tendon diameter and a -16.3 ⁇ 5.6 percentage change in tendon length.

Abstract

L'invention concerne un collier de greffe pour une fixation d'un tendon sur un os. Dans un mode de réalisation, le collier de greffe comprend une feuille de filet biopolymère. Dans un autre mode de réalisation, le collier de greffe comprend un filet de fibres polymères. Dans un autre mode de réalisation, le collier de greffe comprend (a) une première zone comprenant un filet biopolymère et un hydrogel, et (b) une seconde zone voisine à la première zone, et comprenant un filet biopolymère. Dans un autre mode de réalisation, le collier de greffe comprend (a) une première zone comprenant un filet de fibres polymères et de l'hydrogel, et (b) une seconde zone voisine de la première zone, et comprenant un filet de fibres polymères.
PCT/US2007/025127 2006-12-06 2007-12-06 Dispositif d'échafaudage pour favoriser une fixation tendon sur os WO2008070186A2 (fr)

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US9427495B2 (en) 2004-03-05 2016-08-30 The Trustees Of Columbia University In The City Of New York Multi-phased, biodegradable and oesteointegrative composite scaffold for biological fixation of musculoskeletal soft tissue to bone
US7767221B2 (en) 2004-03-05 2010-08-03 The Trustees Of Columbia University In The City Of New York Multi-phased, biodegradable and osteointegrative composite scaffold for biological fixation of musculoskeletal soft tissue to bone
US8864843B2 (en) 2007-02-12 2014-10-21 The Trustees Of Columbia University In The City Of New York Biomimmetic nanofiber scaffold for soft tissue and soft tissue-to-bone repair, augmentation and replacement
US10265155B2 (en) 2007-02-12 2019-04-23 The Trustees Of Columbia University In The City Of New York Biomimmetic nanofiber scaffold for soft tissue and soft tissue-to-bone repair, augmentation and replacement
EP2155112A1 (fr) * 2007-06-11 2010-02-24 The Trustees of Columbia University in the City of New York Échafaudage multiphase implantable entièrement synthétique
EP2155112A4 (fr) * 2007-06-11 2012-11-21 Univ Columbia Échafaudage multiphase implantable entièrement synthétique
EP2367595A1 (fr) * 2008-11-24 2011-09-28 Georgia Tech Research Corporation Systèmes et procédés pour modifier des structures anatomiques
EP2367595A4 (fr) * 2008-11-24 2014-11-19 Georgia Tech Res Inst Systèmes et procédés pour modifier des structures anatomiques
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US8663325B2 (en) 2009-07-09 2014-03-04 Smith & Nephew, Inc. Tissue graft anchor assembly and instrumentation for use therewith
US9333020B2 (en) 2009-07-09 2016-05-10 Smith & Nephew, Inc. Tissue graft anchor assembly and instrumentation for use therewith
US9364276B2 (en) 2009-07-09 2016-06-14 Smith & Nephew, Inc Tissue graft anchor assembly and instrumentation for use therewith
US9211114B1 (en) 2011-02-15 2015-12-15 FM-Nanocoat, LLC Method of coating tissue to promote soft tissue and bone tissue healing, involving nanotechnology, and a photonic curing system for use in repairing tissue
CN103919629A (zh) * 2014-04-18 2014-07-16 清华大学 一种韧性组织结构及其3d打印成形设备和方法
CN108403258A (zh) * 2018-06-05 2018-08-17 上海市第六人民医院 一种止点重建型人工肩袖补片及其制造方法
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