Classifications

• • 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
  • 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
  • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
  • A61L31/14—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
  • A61L31/16—Biologically active materials, e.g. therapeutic substances
• • 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
  • A61L2300/404—Biocides, antimicrobial agents, antiseptic agents
  • A61L2300/406—Antibiotics
• • 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
  • A61L2300/416—Anti-neoplastic or anti-proliferative or anti-restenosis or anti-angiogenic agents, e.g. paclitaxel, sirolimus
• • 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
  • A61L2420/00—Materials or methods for coatings medical devices
  • A61L2420/02—Methods for coating medical devices
• • 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
  • A61L2420/00—Materials or methods for coatings medical devices
  • A61L2420/08—Coatings comprising two or more layers

Definitions

• the present invention relates to orthopedic implants.
• Bacterial bone infections such as osteomyelitis are highly destructive pathologies that particularly affect service members and civilians following orthopedic trauma injuries.
• osteomyelitis poses a risk to all patients that receive orthopedic implants. It occurs in 28% of military personnel with combat-related open extremity wounds. It also occurs in 1-4% of individuals receiving a joint replacement. Further, bone injuries have a high risk for systemic spread of infection and a high risk for infection recurrence.
• an orthopedic implant in an embodiment of the invention, includes at least one coating on the surface of the implant.
• the coating has at least one drug and delivery of the drug is selectively triggered by inflammation.
• the drug comprises at least one antibiotic.
• the antibiotic comprises p- anisaldehyde.
• the coating comprises at least two antibiotic drugs.
• the coating comprises p-anisaldehyde and a second antibiotic drug.
• the second antibiotic drug is a cationic antibiotic.
• the second antibiotic drug is selected from the group consisting of vancomycin, gentamicin and tetracycline.
• the second antibiotic drug comprises vancomycin.
• the coating comprises one or more ROS -responsive polymers.
• the one or more ROS-responsive polymers are selected from the group consisting of poly(thioketal P-amino amide) (PTK-BAA), poly(thioacetal P-amino amide) (PTA-BAA), and poly(P-amino ester) (PBAE) chemistries.
• the one or more ROS-responsive polymers comprise one or more PTK-BAA chemistries.
• the coating comprises multiple layers of film.
• the multiple layers of film comprise at least four layers.
• the multiple layers of film are formed using layer-by-layer (LbL) assembly.
• the multiple layers of film alternate between polycation and polyanion layers.
• a method of preventing infection from an orthopedic implant involves implanting an orthopedic implant in a subject.
• the orthopedic implant includes at least one coating on the surface of the implant.
• the coating has at least one drug and release of the drug is selectively triggered by inflammation.
• the coating comprises one or more ROS -responsive polymers.
• the one or more ROS -responsive polymers are selected from the group consisting of poly(thioketal P-amino amide) (PTK-BAA), poly(thioacetal P- amino amide) (PTA-BAA), and poly(P-amino ester) (PBAE) chemistries.
• the coating comprises p-anisaldehyde and a second antibiotic drug.
• the second antibiotic drug is a cationic antibiotic.
• the second antibiotic drug is selected from the group consisting of vancomycin, gentamicin and tetracycline.
• the second antibiotic drug comprises vancomycin.
• the coating comprises multiple layers of film that are formed using layer-by-layer (LbL) assembly.
• FIG. 1 A is a schematic showing a standard orthopedic implant for fracture fixation with bacterial colonization and local bone tissue damage from infection.
• FIG. IB is a schematic showing an orthopedic implant with a responsive antibiotic coating according to the present invention. Further, the figure shows inflammation-triggered antibiotic delivery for improved bone healing.
• FIG. 2 A is a schematic of LbL nanolayered film fabrication using iterative adsorption of charged polyelectrolytes.
• FIG. 2B is a graph showing that responsive LbL films form robust assemblies.
• FIG. 2C is a graph showing that responsive LbL films have tunable drug loading.
• FIG. 3 is a schematic showing that PTK-BAA and PTA-BAA polycations are amenable to LbL film formation and oxidative cleavage.
• FIG. 4A is a graph showing that LbL films constructed with ROS-degradable PTK polymers/protein drugs selectively release encapsulated protein upon oxidation.
• FIG. 4B is a graph showing that LbL films constructed with ROS-degradable PTK polymers/protein drugs strongly correlate with cellular bioactivity levels following film releaseate treatment.
• FIG. 4C is a graph showing that LbL films constructed with ROS-degradable PTK polymers/protein drugs display “on-demand” protein release with pulsed ROS treatment.
• FIG. 5A is a schematic showing an orthopedic implant and three potential coating conditions.
• FIG. 5B is a graph showing the drug release kinetics of the second and third coating conditions of FIG. 5 A.
• FIG. 7A is a graph showing an evaluation of bond persistence over time for various TK-pendant groups.
• FIG. 7B is a graph showing bond persistence over time for DMPTK, LATK and PATK.
• FIG. 7C is a graph showing bond persistence percentage for DMPTK, LATK and PATK.
• FIG. 8 is a schematic showing a process for making LbL film constructed by alternating polycation and polyanion layers.
• FIG. 9A is a schematic of the chemical structure of a PTK-PAA polycation.
• FIG. 9B is a schematic of a synthesis pathway for a PTK-PAA polycation.
• FIG. 10 is a schematic of the chemical structure of vancomycin.
• FIG. 11 is a graph showing a vancomycin calibration curve.
• FIG. 12A is an image of silicon wafers coated with a film according to the present invention.
• FIG. 12B is an image of a custom stainless-steel bar coated with a film according to the present invention.
• FIG. 12C is an image of a custom stainless-steel bar coated with a film according to the present invention.
• FIG. 13 is a schematic showing a femoral defect model.
• FIG. 14 is an image of stainless-steel plates according to the present invention attached to a mouse femur.
• the term “about,” when referring to a value or to an amount of mass, weight, time, volume, pH, size, concentration, or percentage, is meant to encompass variations of, in some embodiments ⁇ 20%, in some embodiments ⁇ 10%, in some embodiments ⁇ 5%, in some embodiments ⁇ 1%, in some embodiments ⁇ 0.5%, and in some embodiments ⁇ 0.1% from the specified amount, as such variations are appropriate to perform the disclosed methods.
• ROS-responsive means the system responds to an increase in naturally occurring biological stimuli (known as reactive oxygen species (ROS)) that is a hallmark of inflammation, disease states, and infection.
• ROS reactive oxygen species
• An ideal treatment for fracture-associated osteomyelitis is prophylactic in nature, preventing or eliminating local bacterial infections before they compromise regenerating bone tissue and necessitate extensive surgical interventions. While local antibiotic delivery from implants has been demonstrated, previous technologies predominantly feature “top-down” engineering strategies that rely on pre-determined drug release rates that often do not match bacterial infection progression or recurrence events.
• the delivery platform of the present invention directly links localized, prophylactic antibiotic release to an infection-specific stimulus to prolong therapeutic delivery profiles. This represents a significant shift from conventional antibiotic delivery schemes and has the potential to truly personalize therapies for injured service members and patients with highly variable disease progression profiles.
• the present invention uses nanoscale drug coatings, fabricated on the surface of orthopedic implants, that are selectively triggered by inflammation. This responsive system discharges antibacterial therapies only when needed, thereby significantly extending the therapeutic delivery window of local antibiotic treatments by creating “on-demand” drug release for combating pathogen recurrences.
• This responsive technology offers an innovative strategy to better treat intermittent and recurrent bone infections without the limitations of passive, short-lived drug release technologies.
• the present invention involves an orthopedic implant comprising at least one drug coating on the surface of the implant, where the drug is selectively triggered by inflammation.
• the drug coating comprises at least one antibiotic.
• the drug coating comprises p-anisaldehyde.
• the drug coating comprises p-anisaldehyde and vancomycin.
• the present invention involves the development of drug loaded antibacterial coatings for orthopedic implants that are ROS responsive.
• the system of the present invention provides an “on-demand” drug delivery with extended-release kinetics. The system mitigates bacterial infection recurrence.
• the ROS (reactive oxygen species) responsive materials are naturally occurring biological mediators. Elevated levels are seen in infection, disease states and inflammation. Referring to FIG.
• the implant may be a naive implant with no coating. This implant has a greater chance of bacterial infection and inflammation.
• the implant may have a non-responsive coating. Such a coating will have a burst drug release. This type of release will provide initial protection, but still presents a chance of reoccurring infection.
• the implant may have a coating according to the present invention. This coating is ROS- responsive. Such a coating provides a responsive drug release, allowing extended protection from infection.
• FIG. 5B a graph shows the drug release kinetics of the second and third coating conditions. The ROS-responsive coating maintains a higher level of encapsulated drug over time.
• the specific strategy of directly incorporating aldehyde-containing antimicrobial compounds into the polymer’s degradable linker is particularly innovative as it significantly increases drug payload incorporation while precisely linking antibiotic discharge to polymer chain scission.
• the described LbL thin film assembly techniques can create robust coatings using a variety of drug compounds, leaving this technology platform ideally situated for utilization in other medical pathologies that require localized pharmacological interventions.
• Osteomyelitis or bacterial infection of bone, marrow, or surrounding soft tissues, remains a destructive pathology for patients with surgically reconstructed bone.
• blast injuries suffered by armed forces members during combat tours often result in open, complex fractures that are susceptible to bacterial colonization and infection.
• Fractures requiring internal fixation are also highly prone to developing osteomyelitis either from initial bacterial seeding of the implant or transmission during hospital care as denoted in FIG. 1A.
• the figure shows recurrent bacterial infection of implant-stabilized bone injuries. These infections can lead to bone tissue necrosis and often require multi-stage revision, first removing the initial implant and compromised bone, administering weeks of systemic antibiotics to eliminate infection, and then performing a final reconstructive procedure.
• LbL assemblies also allow for highly tunable film growth (FIG. 2B) and drug loading (FIG. 2C) with increasing layer depositions.
• biodegradable polymers with tunable erosion profiles are often incorporated into the assemblies.
• Hydrolytically degradable poly(P-amino ester) (PBAE) polymers have previously been employed to control antibiotic release from LbL coatings, though crucially these formulations release over 75% of their drug payload within 48h.
• LbL coatings with “smart” therapeutic delivery that enables selective drug release in response to tissue -produced signals such as reactive oxygen species (ROS).
• ROS reactive oxygen species
• oxidation-triggered antimicrobial delivery from LbL films has not been previously reported.
• the present invention creates a sustained, “on-demand” antibiotic delivery system that selectively releases antimicrobial compounds from surface-coated orthopedic implants in response to elevated ROS levels as illustrated in FIG. IB.
• the figure shows an inflammation-responsive implant coating according to the present invention for on-demand, prophylactic antibiotic delivery to improve bone healing.
• local tissue concentrations of ROS spike during bacterial infection as inflammatory ROS-producing immune cells attempt to quell bacterial proliferation, thus making local ROS concentration a precise signal for initiating local drug delivery.
• the drug delivery window can be drastically extended while also limiting any negative effects on bone growth or osteogenesis associated with excess concentrations of antibiotics.
• PTK-BAA Charged poly(thioketal P-amino amide)
• PTK-BAA Charged poly(thioketal P-amino amide)
• NMR nuclear magnetic resonance
• These polymers feature ionizable tertiary amines alongside ROS- degradable thioketal groups (FIG. 3), respectively making these materials amenable to electrostatic LbL assembly and selective oxidation-mediated film disassociation.
• Vancomycin-loaded LbL films are constructed on model stainless steel plates using alternating adsorptions of cationic PTK-BAA, anionic poly(acrylic acid) (PAA), cationic vancomycin, and then PAA again in a repeating tetralayer architecture. Vancomycin has previously been successfully incorporated into hydrolysis-sensitive LbL assemblies, and was successfully complexed with the PTK-BAA polycation to generate robust LbL films (40 tetralayers) as pictured in FIG. 3. LbL assembly conditions (solution pH, poly electrolyte concentration, dip durations) can be adjusted to maximize per-cycle vancomycin loading.
• vancomycin loading vs. tetralayer depositions can be quantified to determine tunable antibiotic dosing in the coatings.
• Total vancomycin loading can be quantified using high-performance liquid chromatography (HPLC) following whole-film disassociation in high salt conditions. Vancomycin loading of lOpg per cm 2 of film surface area is achievable with these LbL systems and provides potent antimicrobial activity.
• HPLC high-performance liquid chromatography
• PBAE hydrolytically degradable poly(P-amino ester)
• PBAE hydrolytically degradable poly(P-amino ester)
• PTA- BAA poly(thioacetal P-amino amide)
• FIG. 3 a poly(thioacetal P-amino amide) (PTA- BAA) polymer-drug conjugate was synthesized and evaluated as an LbL film constituent (FIG. 3).
• PTA-BAA films more strongly inhibit bacterial growth since they deliver both film-loaded vancomycin alongside a polymer-conjugated antibiotic upon oxidative triggering.
• Thioketal and thioacetal bonds are both sensitive to oxidation, though polymeric drug delivery systems featuring either of these ROS cleavable linkers have primarily relied on simple polymer chain degradation and loss of electrostatic or hydrophobic interactions with drug compounds to facilitate release.
• thioketals and thioacetals can also be respectively synthesized from more complex compounds featuring unprotected ketone or aldehyde groups.
• the strategy disclosed herein covalently incorporates a drug molecule directly into the degradable linker, so oxidation of the thioketal or thioacetal group not only cleaves the polymer chain but liberates the intact bioactive drug compound.
• a comparable strategy has been recently pursued using aldehyde-based antimicrobials though by employing similarly synthesized polymers with pH-sensitive acetal linkers instead of thioacetals.
• the present invention modifies this approach by delivering the antimicrobial compound p-anisaldehyde from thioacetal polymer-drug conjugates via ROS-mediated drug liberation (FIG. 3).
• p-anisaldehyde is used to generate PTA-BAA polymers using previously described protocols before confirming polymerization by GPC and NMR.
• PTA-BAA degradation and p-anisaldehyde release kinetics following treatment with escalating doses of the model ROS model hydrogen peroxide (0, 0.1, 1, 10, 100 mM H2O2) is determined by NMR.
• the PTA-BAA polycations is similarly complexed into LbL assemblies with vancomycin to create dually-loaded coatings.
• Per-layer drug encapsulation, along with drug loading vs. layer depositions, can be optimized and quantified as described above.
• both PTK-BAA and PTA-BAA polymers will successfully form stable vancomycin LbL films, feature selective and dose-dependent ROS-triggered drug release, and to cause minimal toxicity to mammalian cells.
• PTA-BAA films elicit greater antimicrobial effect due to their co-delivery of p-anisaldehyde with vancomycin upon oxidative polymer degradation, and can be carried forward for in vivo testing.
• ROS -responsive coatings will significantly prolong drug delivery in vivo compared against the conventional non-responsive formulations.
• Alternate methods for assembling the PTK-BAA / vancomycin LbL films of the present invention can be used. Additionally, the molecular weight of the polyanion used in LbL film construction can be modulated to adjust antibiotic release kinetics upon ROS triggering, presenting a simple strategy fortuning oxidative sensitivity in these systems. Regarding testing, the Xen29 S. aureus strain has been successfully used to elicit osteomyelitis in rat long bone defects. Employing an antibiotic-coated bone plate will effectively recapitulate a relevant clinical scenario for stabilizing infection-prone open fractures, and bone plates are commonly used for fracture fixation in rat models.
• a press-fit implant with the respective antibiotic coating can be directly inserted into the surgical defect for fixation-free administration.
• Dosing for the antibiotic payload can be modulated by increasing vancomycin layers in the LbL assembly (FIG. 2C) or by changing the LbL’s polyanion.
• Example 1 ROS-responsive release and antimicrobial activity of film-discharged therapeutics
• Vancomycin LbL films constructed with three polycations ROS-degradable PTK- BAA, ROS-degradable and anisaldehyde-releasing PTA-BAA, and hydrolytically-degradable PBAE are formed on the surface of stainless steel plates at matching vancomycin doses.
• coated samples are incubated at 37°C in escalating doses of H2O2 (0, 0.1, 1, 10, 100 mM) dissolved in PBS at pH 7.4.
• drug-loaded films are also incubated in pulsed doses of 1 mM H2O2 to mimic infection recurrence events that ramp local tissue inflammation up or down.
• releaseate are collected every 2 days to measure vancomycin and panisaldehyde concentrations with HPLC.
• ATC Staphylycoccus aureus bacteria
• aureus bacteria 105 CFU/mL in cation-adjusted Mueller Hinton broth
• PBS treatment positive (PBS treatment) controls
• S. aureus inhibition by film-released antibiotics is assessed using a LIVE/DEAD BacLight Bacterial Viability Assay (Integra Biosciences).
• naive film constituents and drug-loaded films are incubated with murine MC3T3-E1 osteoblasts (ATCC) in standard culture media at 37°C for 24h and quantified for number of viable cells using a Cell TiterGLO assay (Promega).
• ATCC murine MC3T3-E1 osteoblasts
• S. aureus 5 x 10 5 CFU
• Release of fluorescently-tagged vancomycin from the ROS responsive and non- responsive control coatings are non-invasively monitored by fluorescent IVIS imaging (Perkin Elmer).
• the luminescent ROS-reporter molecule luminol are administered to the animals to measure local ROS production kinetics at the infected bone injury sites via luminescent IVIS imaging. To mimic a bacterial recurrence event, after 14 days the bone defects are re-inoculated with bacteria and monitoring is continued for vancomycin release and ROS production by IVIS until day 35.
• the bone defects are also re-inoculated with bacteria at day 14 to mimic an infection recurrence event.
• non- invasive microcomputed tomography pCT
• Animals are humanely euthanized at week 8 and analyzed via swabbing and bacterial plating to assess S. aureus persistence, scanning electron microscopy of bone explants to gauge biofilm formation, and histology to assess bone tissue morphology via trichrome staining.

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• 2023
  • 2023-10-11 EP EP23892192.8A patent/EP4601467A2/de active Pending
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