Classifications

• • 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
  • A61F2/0077—Special surfaces of prostheses, e.g. for improving ingrowth
• • 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
• • 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
• • 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
  • A61F2/0077—Special surfaces of prostheses, e.g. for improving ingrowth
  • A61F2002/0086—Special surfaces of prostheses, e.g. for improving ingrowth for preferentially controlling or promoting the growth of specific types of cells or tissues
• • 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
  • A61F2/0077—Special surfaces of prostheses, e.g. for improving ingrowth
  • A61F2002/009—Special surfaces of prostheses, e.g. for improving ingrowth for hindering or preventing attachment of biological tissue
• • 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
  • A61F2210/00—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2210/0004—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof bioabsorbable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0037—Other properties
  • B29K2995/0059—Degradable
  • B29K2995/006—Bio-degradable, e.g. bioabsorbable, bioresorbable or bioerodible

Definitions

• the invention relates to biocompatible substrates having a surface topography which has a low tendency for cells to adhere thereto. This has particular application for the production of prostheses or implants requiring low adhesion of cells.
• the present invention is based on the surprising observation that surfaces having a pattern of tiny projections, usually of nanometer dimensions, inhibit the adhesion of cells thereto. This has application in the preparation of surfaces which resist the adhesion of cells.
• a particular aspect of the present invention provides a biocompatible substrate having a surface comprising an array of projections or pits, said projections being of a size and spacing such that cells have a low tendency to attach to the surface.
• the substrate will be introduced into a living or other biologically sensitive environment and is therefore to be formed of a biocompatible material.
• Biocompatible materials including but not restricted to biodegradable and bioabsorbable materials
• biodegradable and bioabsorbable materials are well known in the art and will be chosen having regard to the particular biological environment into which they are to be introduced .
• the present invention allows surfaces to be provided which have a reduced tendency of cell adhesion thereto. In this way, the tendency of cells to adhere or not to a particular surface can be controlled.
• the process can also be used to build complex tissue structures with seeding of one cell type into gaps in another cell type. For example, where the substrate includes areas of projections/pits and planar areas, cells can be preferentially adhered to the planar areas.
• An adhesive material e.g. laminin
• the further cells adhere preferentially to the laminin-coated areas having projections/pits and avoid adhering to the pre-existing monolayers of cells (over the planar areas).
• the low adhesion tendency is less than 50%, particularly less than 30% of that of a corresponding planar surface.
• Biocompatible substrate on which it may be desirable to inhibit cell adhesion include implants, grafts and prostheses introduced into the vascular system, gastrointestinal tract, lung alveolae, synovia, connective tissue and in the eye or gum and in any part of the body which should normally have void spaces filled with liquid or gas but does not - as a consequence of injury or disease.
• a particular application is to prevent adhesion of undesired cells to ligaments under repair.
• a biocompatible substrate for ligament repair may be patterned on an inner surface intended to be wrapped around the ligament with a surface topography intended to promote repair of the damaged ligament (see our parent application PCT/GB95/00350) ; and may be patterned with a surface topography on the outer side intended to prevent undesired adhesion of other types of cells to the outside of the ligament which would reduce its mobility.
• a sheet-like substrate may be patterned on both sides with adhesion- reducing projections or pits, which may be used as a separation layer to prevent two adjacent structures adhering to each other.
• projections or pits of nanometer dimensions can inhibit cell adhesion.
• the cross sectional dimension and height of each projection is in the range l ⁇ -250nm, particularly in the range 20- lOOnm and especially 25-75nm.
• Corresponding dimensions apply to pits.
• a projection is characterised by having an area of reduced height all around it.
• a pit has an area of increased height all around it.
• the projection or pit may be of any cross-section, including circular, oval, square, rectangular, polygonal etc.
• the projections or pits will be present in an array, which may be in any chosen pattern, such as a square pattern, a rectangular pattern, a circular pattern, a rosette pattern, a random pattern etc.
• the centre-to-centre spacing of the projections or pits can be a determinative factor in controlling the degree of resistance to cell adhesion, with wider spacings favouring reduced cell adhesion.
• the spacing is generally in the region 20-500 nm, particularly 40-300 nm, especially 75-200 nm.
• the biocompatible substrate may, if desired, be formed of a resorbable material which becomes resorbed into the living tissue within a chosen period of time, usually a number of days, following implantation.
• a substrate intended to prevent adhesion of tissue structures during a healing process could become resorbed after fulfilling its function.
• Bioresorbable materials are well known in the art and include compounds such as glycol ide-co-lactide polymers.
• the nano-substrate can be formed by techniques well known in the manufacture of structures of nanometer dimensions, such as those used in fabrication of semi conductor microcircuits and/or in the production of compact discs.
• the process employs lithography followed by etching to produce the nanometric topography, either directly into the material or so as to form a master for patterning softer materials by embossing, casting or moulding.
• Materials suitable for direct patterning include hard materials such as silicon, silica and perspex.
• materials to be produced by mechanical transfer are polymeric materials, which may be optionally heated.
• the basic technique is to use lithography to define the pattern and etching transfer the pattern into the underlying substrate.
• the lithography used has to have the desired resolution required to make the pattern for the pillars that are between 10 and 250nm in diameter.
• Electron beam and ion beam direct write lithography and electron ion projection and X-ray printing are all suitable.
• the lithographic process defines a pattern in a suitable radiation-sensitive resist. This resist may be used directly as a mask for the subsequent etching process, or it may be used as an intermediate mask to transfer the pattern into any intermediate layer, which acts as the mask for the etching process, or it may be used as a stencil which after the deposition of an intermediate layer.
• the resulting etch resistant mask is then used to allow transfer of the pattern into the hard material. This transfer is done by etching that may be done using chemicals in liquid form or by using ions that form a volatile product with the material.
• the titanium is etched in an electron cyclotron resonance/reactive ion etching machine using the negative resist as a mask. Silicon tetrachloride at a flow rate of 15 sscm gives a pressure of 4 mTorr .
• the microwave power is 150W, the rf power 24W and the dc bias observed -88V.4 minutes is required to etch the 50 nm of titanium.
• embossing can be adapted for some polymeric materials
• moulding including injection moulding
• the die itself can be made by method 1 (suitable for hard materials) .
• Embossing involves heating the plastic to less than its melting temperature and pressing the die into the plastic.
• casting the plastic is dissolved in a suitable solvent, poured over the mould and after evaporation of the solvent, peeled off the die.
• moulding plastic is melted over the die with some pressure applied in the case of injection moulding.
• a die of 50 nm pillars 100 nm high is formed in fused silica as described above.
• the clamp is released leaving an embossed polymeric sheet, ready for sterilisation and use with cells.
• the procedure is described for cellulose acetate. It works well with a variety of thermo-setting polymers, including biodegradable (i.e. resorbable) polymers. A suitable temperature has to be found for each material - 30 degrees less the glass transition is found to be good starting point for experimentation.
• the process can be adapted to produce either pillars or pits.
• the macrophage line P388D1 was grown in RPMI 1640 medium.
• Epitena (Wojciak-Stothard e a. J. Materials Science, 6, 266-271 (1995) were grown from cultures isolated from rat flexor tendon in the same medium grown for 20-30 passages.
• B10.D2.PCE endothelia were obtained from laboratory stocks and grown in Hams F10 medium with 3% foetal calf serum and insulin-transferrin-selenite supplement .
• MEM Minimal Essential Medium
• EDTA calcium and magnesium ion-free Hanks
• Adhesion measurements on nanopillars were done with 1 hour exposure of the cells to the substratum at 37C after trypsinisation of the epitenon cells. Unattached cells were then removed by gentle shaking and pouring off the medium. The attached cells were counted and adhesion is expressed as a percentage of the maximal possible attachment (i.e. all cells attaching).
• Results are shown in Tables 1 and 2.
• the adhesion of cells to the surface having the nanopillars is markedly lower than en the corresponding planar surface.

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• Health & Medical Sciences (AREA)
• Cardiology (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Transplantation (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Vascular Medicine (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Prostheses (AREA)
• Immobilizing And Processing Of Enzymes And Microorganisms (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (7)

Cited By (35)

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Citations (8)

Family Cites Families (2)

• 1998
  • 1998-03-11 GB GBGB9805214.5A patent/GB9805214D0/en not_active Ceased
• 1999
  • 1999-03-10 JP JP2000535276A patent/JP2002505907A/ja active Pending
  • 1999-03-10 AU AU27391/99A patent/AU2739199A/en not_active Abandoned
  • 1999-03-10 US US09/623,751 patent/US6720469B1/en not_active Expired - Fee Related
  • 1999-03-10 WO PCT/GB1999/000721 patent/WO1999045860A1/en not_active Ceased
  • 1999-03-10 EP EP99907761A patent/EP1061864A1/en not_active Withdrawn
  • 1999-03-10 CA CA002322456A patent/CA2322456C/en not_active Expired - Fee Related

Patent Citations (8)

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