BIOENGINEERED CORNEAL GRAFTS

Abstract

The present invention discloses bioengineered corneal grafts for treating either or both Keratoconus and visual impairment, selected from (i) a corneal Onlay comprises or coated by at least one member of Group A, consisting of biocompatible synthetic materials; at least one member of Group B, consisting of at least one type of biological polymer and optionally, at least one member of Group C, consisting of at least one type of protein and (ii) An intrastromal corneal lenticule graft, configured to mimic native corneal stroma tissue by means of its optical properties, mechanical properties, permeability and interaction with corneal stromal cells; wherein at least one portion of said lenticule comprises or coated by at least one member of Group D, consisting of transparent crosslinked hydrogel; at least one member of Group E, consisting of collagen; collagen methacrylate, recombinant mammal collagen, mammal-sourced collagen; and optionally, at least one member of Group F, consisting of Keratocytes and/or stem cells and any combination thereof. The present invention further discloses compositions, methods for production, implementation and treatment of medical indications by aforesaid corneal graft.

Claims

1.-40. (canceled)

41. A corneal graft for treating either or both Keratoconus and visual impairment, the corneal graft selected from: (i) a corneal Onlay comprising or coated by: at least one member of group A, consisting of biocompatible synthetic materials; at least one member of group B, consisting of at least one type of biological polymer; and at least one member of group C, consisting of at least one type of protein, and (ii) an intrastromal corneal lenticule graft, configured to mimic native corneal stroma tissue by means of its optical properties, mechanical properties, permeability and interaction with corneal stromal cells; wherein at least one portion of said lenticule comprises or is coated by: at least one member of group D, consisting of transparent crosslinked hydrogel; or at least one member of group E, consisting of collagen; collagen methacrylate, recombinant mammal collagen; and mammal-sourced collagen; or at least one member of group F, consisting of Keratocytes and/or stem cells and any combination thereof, wherein said Onlay is made by (a) prematurating one or more of the following: seeding stem cells; Limbal stem cells; Epithelial cells on its anterior surface, and then (b) removing said cells prior to graftation.

42. The graft of claim 41, wherein said group A consists at least one of the following: HEMA, HEA, MAA, MMA, MPC, PEG, PCL, PVA and any mixture or combination thereof.

43. The graft of claim 41, wherein said group B consists at least one of the following: collagen, recombinant mammals' collagen, ColMA, gelatin, GelMA, Elastin and any mixture or combination thereof.

44. The graft of claim 41, coated by one or more of the followings: collagen, laminin fibronectin or a combination thereof.

45. The graft of claim 41, wherein said Onlay is made in a method consisting of incorporating one or more of the followings: limbal stem cells and epithelial cells, on its anterior surface.

46. The graft of claim 41, wherein said Onlay is made by one or more techniques selected from the group consisting of molding, 3D-printing, laser-ablating and a combination thereof.

47. The graft of claim 41, wherein said Onlay comprises sub-micron sized pores.

48. The graft of claim 41, wherein said Onlay is coated by recombinant human collagen.

49. The graft of claim 41, wherein one or more of the following is true: a. said Onlay has an optical refractive index that is similar to the native corneal stroma, to avoid light scattering and/or reflections; b. said Onlay at least partially blocks UV light; and c. said Onlay is marked for orientation purposes by a laser engraving, mechanical pressure, pigmented ink, or a combination thereof.

50. A method of grafting an Onlay of claim 41, wherein at least one of the following is held true: a. said method comprises a step of shaping said Onlay using a laser after grafting; b. said method comprises a step of shaping said Onlay using a laser after grafting and a maturation period; and c. said method comprises a step of utilizing an insertion tool.

51. The graft of claim 41, wherein at least one of the following is true: a. said lenticule is configured for a spherical refractive correction in the range between about −10 diopters to about 15 diopters; b. said lenticule has a non-spherical shape for astigmatism vision correction; c. said lenticule has a shape for patient-tailored vision correction; d. said lenticule has an optical refractive index which is similar to native corneal stroma, to avoid light scattering and/or reflections; e. said lenticule has an elastic modulus between about 50 kPA and about 13 MPa; f. said lenticule has a permeability to glucose, oxygen, and proteins that is comparable to native corneal stroma tissue; g. said lenticule is configured to make possible the migration of corneal stroma cells; and h. said lenticule at least partially blocks UV light.

52. A method for the production of an intrastromal corneal lenticule graft for either or both Keratoconus treatment and vision-correction, configured to mimic native corneal stroma tissue by means of its optical properties, mechanical properties, permeability and interaction with corneal stromal cells; wherein said method comprises the steps of a. providing at least one portion of said lenticule to comprise or to be coated by at least one member of group D consisting of transparent crosslinked hydrogel; at least one member of group E, consisting of collagen; collagen solution, collagen methacrylate, recombinant mammal collagen, mammal-sourced collagen; or at least one member of group F, consisting of Keratocytes and/or stem cells and any combination thereof; and b. processing the same by a method selected from 3D printing, laser ablating, molding, and any combinations thereof.

53. The method of claim 52, wherein collagen of group E is used to make hydrogels of group D.

54. The method of claim 52 comprising the step of 3D printing and/or molding the collagen solution, and crosslinking the same to form a transparent hydrogel.

55. The method of claim 52, comprising the step of concentrating the collagen solution to a predefined value in the range of about 1 to about 15% w/v.

56. The method of claim 52, wherein said crosslinking is provided by admixing photoinitiator to said collagen solution and applying light on it.

57. The method of claim 54, wherein said crosslinking is provided by admixing EDC and/or NHS molecules to said collagen solution.

58. The method of claim 54, wherein said crosslinking is provided in a controlled gas mixture environment, other than air.

59. The method of claim 52, comprising scanning said lenticule by an OCT, simultaneously to ablating, hence forming a closed-loop feedback mechanism.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The various features and advantages of the present invention may be more readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings in which

[0067] FIG. 1 schematically illustrates a corneal Onlay according one embodiment of the present invention;

[0068] FIG. 2 schematically illustrates a corneal intrastromal lenticule graft according to one embodiment of the present invention, reference is made to currently available link https://commons.wikimedia.org/wiki/File:Hypermetropia.svg which is incorporated herein; and

[0069] FIG. 3 shows OCT scans of an intrastromal lenticule graft before and after laser processing, in accordance with a few embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0070] It is according to a few embodiments of the invention wherein the hereto disclosed technology provides novel corneal grafts; and more specifically, bioengineered corneal Onlays and Inlays. The invention also discloses novel corneal grafts' compositions, methods for their production and inserting, transplanting and/or grafting into the cornea, and methods for treating a medical condition of a patient.

[0071] While this invention has been described with respect to various specific examples and embodiments, it is to be understood that the invention is not limited thereto and other embodiments are within the scope of the invention.

[0072] The terms “corneal graft” and “corneal implant” interchangeably refer hereinafter to a bioengineered construct that is designed to be implantable in a mammalian (e.g., human) eye and to have properties of at least part of a cornea. The terms further refer to either and both corneal Inlays and Onlays. Cornea transplant (keratoplasty) is a surgical procedure to modify properties of part of the cornea with corneal tissue from a donor or a “synthetic” cornea or portions thereof.

[0073] The term “Inlay” “intrastromal corneal lenticule graft” interchangeably refer to an intracorneal Inlay, e.g., an alloplastic lenticule placed at the interface of the free corneal cap and the stromal bed or in a corneal pocket.

[0074] The term “Onlay” refers to corneal graft, namely an implantable lens or portion thereof, that is placed between Bowman's membrane of the cornea of an eye and the corneal epithelium of the eye.

[0075] The term “grafting” and “implanting” interchangeably refers, when relevant, to medical procedures of inserting, grafting, and transplanting of corneal Inlay or corneal Onlay onto or into the cornea.

[0076] Unless otherwise stated, with reference to numerical quantities, the term “about” refers to a tolerance of ±25% about the stated nominal value.

[0077] A first aspect of the invention, is to disclose affordable, stable, biocompatible, easily-implantable and patient-tailored corneal Onlay:

[0078] It is according to a few embodiments of the invention wherein the Onlay comprises or coated by at least one member of Group A, consisting of biocompatible synthetic materials; at least one member of Group B, consisting of at least one type of biological polymer and optionally at least one member of Group C, consisting of at least one type of protein.

[0079] It is according to a few embodiments of the invention wherein the thicknesses of the grafted member is ranging between about 30 to about 200 microns. Diameter of about 7 mm. Refractive correction is ranging from about −15D to about +20D, spherical or with astigmatism correction. Possibly having thinner periphery. Possibly incorporating marks for astigmatism axis alignment.

[0080] It is according to yet other embodiments of the invention wherein the Onlay is made of natural occurring compositions, including polymers. Such polymers are selected from a group consisting, inter alia, collagen and/or collagen methacrylate, human, animal or recombinant source, e.g., about 1 to about 15% w/v; fibronectin; elastin, laminin and any combination thereof.

[0081] It is according to other embodiments of the invention wherein biocompatible synthetic polymers are provided useful, including polymers that are selected from a group consisting, inter alia, 2-hydroxyl methacrylate (HEMA); 2-hydroxyethylacrylate (HEA); Methyl methacrylate (MMA); Methacrylic acid (MAA); Methacryloyloxyethyl phosphorylcholine (MPC); Poly(ethylene glycol) (PEG) and/or Poly(ethylene glycol) diacrylate (PEGDA) and/or poly(ethylene glycol) dimethacrylate (PEGDMA), Multi-arm Poly(ethylene glycol) diacrylate; Poly(ε-caprolactone) (PCL); Poly(vinyl alcohol) (PVA); Photo-initiator LAP; Irgacure 2959; APS-TEMED and any combination thereof.

[0082] It is according to other embodiments of the invention wherein the Onlay is characterized by the following parameters: it is transparent (e.g., more than 85% visible light transmission, less than 5% haze); stiffness similar to natural cornea (about 50 kPa to about 13 MPa), to enable healthy epithelial cells growth; it is permeable to glucose and proteins, similarly to native corneal stroma and not less than about 10{circumflex over ( )}−6 cm{circumflex over ( )}2 per sec for glucose; it enables epithelium cells growth on anterior surface and the formation of healthy epithelial layers; it comprises high water content, it is non-degradable or has long term stability; it is biocompatible with low immune response, not induce fibrosis, and it can be shaped with laser processing and/or 3D printing or molding.

[0083] It is according to other embodiments of the invention wherein the Onlay is substantially mainly synthetic, as the enzymatic activity in the epithelium is relatively high, and natural hydrogel would be degraded significantly after grafting. It is possible that Onlay based on natural compounds would be remodeled by the body and form native tissue.

[0084] In order to improve vision in presbyopia, myopia, hyperopia and astigmatism patients, a transparent, permeable hydrogel can be grafted into the cornea, below the epithelium layer, to fix the curvature of the cornea. Onlays can be referred to as permanent bio-compatible contact lenses. The development of an Onlay graft has two main challenges: (1) the surface of the Onlay should be protein-based in order to enable normal epithelium growth above it. Yet, the Onlay needs to be non-degradable in order achieve stable vision correction; and, (2) the Onlay must be permeable to glucose and nutrients in order to nourish the epithelium layer. A healthy epithelium is essential as it acts as a protective barrier to keep bacteria, dust and other foreign substances from penetrating the eye.

[0085] The combination between natural and synthetic polymers disclosed herein are designed to address these challenges and form a viable solution for refraction-corrective Onlays. In preferred embodiments, the Onlay comprises a hydrogel layer and a coating layer. The hydrogel layer is made of biocompatible synthetic polymer, with additional bio-mimicking substances, and the coating is made of biological proteins which present binding sites and other nutrients and indicators for the epithelial cells.

[0086] The Onlay lens graft can be molded, 3D printed, or laser ablated to the required curvature and geometry. In some cases, the grafted lenticules are designed specifically to the patient, allowing better correction of the refractive disorder.

[0087] It is according to other embodiments of the invention wherein the preparation methods consists, inter alia, the following steps: (a) mixing materials; (b) injecting into mold and/or 3D printing; (c) photo and/or thermal polymerization; (d) washing out residues; (e) possibly laser processing; (f) possibly applying an additional coating layer to allow cells growth; (g) possibly seeding epithelial and/or limbal and/or stem cells on top of the Onlay for a maturation period (see below); (h) testing (refraction, transparency, homogeneity etc.); and (i) applying thrombin and/or fibrinogen on the posterior side

[0088] The maturation-period is provided herein useful for seed cells in vitro on top of the Onlay, after or instead the coating process, and let them mature the Onlay and produce binding sites and/or ECM and/or collagen for better and faster epithelization after grafting. After the maturation period the cells are removed to minimize any immune response, and the Onlay is tested and grafted.

[0089] It is according to other embodiments of the invention wherein graft of the Onlay is provided useful by the following method: (a) removing the epithelium and exposing the Bowman's layer; (b) applying fibrinogen and/or thrombin on the Bowman's layer; (c) aligning and attaching the Onlay to the cornea for about 10 to about 60 seconds, possibly with a designated tool; (d) Possibly applying protective contact lens to prevent dry eyes and infections; and (e) possibly post-treating with nutrients, steroids, antibiotics and lubricants for up to four weeks.

[0090] It is according to other embodiments of the invention wherein shaping is provided by one of the following techniques: Laser processing of the lenticule before grafting, according to patient's OCT scan; Laser processing of the lenticule immediately after grafting; and/or Laser processing of the lenticule after a maturation period (about 1 day to about 12 weeks), during which the cornea heals and possibly changes its geometry.

[0091] As an example, and in a non-limiting manner, an Onlay according to an embodiment of is at least partially made of a combination of biocompatible synthetic materials and biological polymers and proteins as defined below, such that at least one of the following is being held true: (a) the Onlay is made by composition selected from a group consisting HEMA, HEA, MAA, MMA, MPC, PEG, PCL, PVA or any mixture or combination thereof, and collagen, ColMA, gelatin, GelMA, Elastin or any mixture or combination thereof; (b) the Onlay is coated with collagen, laminin or fibronectin to allow epithelium growth; (c) the Onlay is made in a method consisting of a pre-maturation step of seeding stem cells; Limbal stem cells; Epithelial cells on its anterior surface, and removing the cells prior to grafting; (e) the Onlay is made in a method consisting of incorporating limbal stem cells and/or epithelial cells on its anterior surface; (f) the Onlay is made in a method consisting of is 3D-printing to the required shape for optimal and/or patient-specific vision-correction; (g) the Onlay is made in a method consisting of laser-ablating to the required shape for optimal and/or patient-specific vision-correction; (h) after grafting, the Onlay is processed using laser systems to the required shape for optimal and/or patient-specific vision-correction; (i) the Onlay comprises sub-micron sized pores to allow permeability of glucose and nutrients. Other embodiments disclose a method for improving a person's vision, comprising a step of grafting an Onlay as defined in any of above and a corneal device for improving a person's vision, comprising an Onlay as defined in any of the above.

[0092] As an example, and in a non-limiting manner, an Onlay is made of a composition ranging from 10 to 30% HEMA and 5 to 25% HEA, and 0.2 to 2% collagen methacrylate (w/v), with 0.1 to 1% Irgacure 2959 as a photo-crosslinker.

[0093] In order to produce Onlays, the following methods were used: (a) materials are thoroughly mixed in aqueous solution and centrifuged for bubbles extraction; (b) The composition is then injected into a transparent glass mold, which designed to form a 200 to 300 microns thick hydrogel, with no optical power, but having a base curve radius of 8.0 to 10.0 to fit corneal anterior surface curvature. (c) Mold is then inserted into a crosslinking light chamber for 5 to 10 minutes at irradiance of 5 to 10 mW per cm{circumflex over ( )}2. (d) Yielded crosslinked hydrogel is then washed for 24 to 72 h in aqueous solution to remove residues. (e) The hereto washed hydrogel is then placed within an excimer laser system, and ablated to form a lenticule with an optical power according to an OCT scan of the patient's eyes. (f) The resulting Onlay lenticule is scanned by an OCT system to assure its optical properties. (g) lenticules are possibly marked using Gentian Violet surgical marker, by an arrow shaped and an “S” shaped marks, for easier grafting orientation. Prior to implantation, Onlay are submerged in 0.1 mg per ml collagen solution for 30 to 60 minutes, followed by several gentle washes.

[0094] A second aspect of the invention, is to disclose affordable, stable, biocompatible, easily-implantable and patient-tailored corneal Inlay, also termed as intrastromal corneal lenticule graft:

[0095] It is according to other embodiments of the invention wherein intrastromal corneal lenticule graft is provided useful for either or both Keratoconus treatment and vision-correction. The intrastromal corneal lenticule graft is configured to mimic native corneal stroma tissue by means of its optical properties, mechanical properties, permeability and interaction with corneal stromal cells. In this intrastromal corneal lenticule graft, at least one portion of the lenticule comprises or coated by at least one member of Group D, consisting of transparent crosslinked hydrogel; at least one member of Group E, consisting of collagen; collagen methacrylate, recombinant mammal collagen, mammal-sourced collagen; and optionally, at least one member of Group F, consisting of Keratocytes and/or stem cells and any combination thereof.

[0096] In order to improve vision in keratoconus and hyperopia patients, a collagen-based hydrogel of the present invention can be grafted into the corneal stroma, mimicking the functionality and characteristics of the natural tissue. In some cases, the grafted lenticules are designed specifically for the patient, allowing better correction of the refractive disorder. In some embodiments of the current invention, the graft is made of recombinant human collagen with additional proteins and polymers, allowing the graft to integrate and fuse with surrounding tissue over time. In some embodiments of the current invention, stem cells or keratocytes cells are incorporated into or on the surface of the graft. In some cases, the graft can be grafted into a corneal flap made by a laser. In some embodiments of the current invention, the graft is molded, 3D printed, or laser ablated to the required curvature and geometry.

[0097] Reference is now made to FIG. 2 which schematically illustrates an intrastromal corneal lenticule graft according to a few embodiments of the present invention.

[0098] It is according to a few embodiments of the invention wherein the intrastromal lenticule graft is characterized by thicknesses ranging between about 30 to about 250 microns. Diameter is ranging from about 4 to about 9 mm. Refractive correction varies from about −10D to about +15D, spherical or with astigmatism correction, or customized for a specific patient's corneal condition. The lenticule is characterized by a possible thinner periphery and/or a possible mark for astigmatism axis alignment.

[0099] In a few embodiments of the invention, intrastromal lenticule is made by compositions comprising collagen. The collagen is selected from a group consisting of collagen and/or Collagen methacrylate; collagen of human, animal, or recombinant source, e.g., from about 1% to about 15% w/v., preferably between about 6 and about 13% w/v, where native corneal stroma has about 13% collagen.

[0100] In a few embodiments of the invention, intrastromal lenticule is made by compositions comprising additional natural polymers. Including those selected from a group consisting of gelatin and/or gelatin methacrylate, hyaluronic acid (HA) and/or N-(2-hydroxypropyl) methacrylamide (HAMA), elastin, fibronectin, or a mixture thereof.

[0101] In a few embodiments of the invention, intrastromal lenticule is made by compositions comprising biocompatible synthetic polymers. including those selected from a group consisting of PEG and its derivatives (PEGDA, PEGDMA, multi-arm PEG); 2-Hydroxyethyl methacrylate HEMA; HEA; PCL; poly(lactic-co-glycolic acid) (PLGA); MPC; and/or additional proteins, such as Laminin, as defined in Aumailley, Monique, et al. “A simplified laminin nomenclature.” Matrix biology 24.5 (2005): 326-332.

[0102] In a few embodiments of the invention, intrastromal lenticule is made by utilizing photo-initiator(s) crosslinker, such as LAP, and commercially available Irgacure 2959 product by Sigma-Aldrich, USA. It possibly may comprise biocompatible dye for easy handling. In other embodiments of the invention, the lenticule is made utilizing other crosslinkers, such as EDC and/or NHS molecules.

[0103] It is according to a few embodiments of the invention wherein the invention as disclosed here provided useful means, compositions and methods of corneal transplantation or corneal Inlay grafting with cross-linking for preventing an immune response to a corneal graft and/or rejection of the corneal graft by the patient, and for preventing vascular and/or fibrous tissue growth on, and surrounding a keratoprosthesis lens or other type of corneal graft or Inlay.

[0104] It is according to a few embodiments of the invention wherein the intrastromal lenticule graft of the present invention is characterized by the following parameters: it is transparent (<85% visible light transmission, >3% haze); its stiffness is similar to central corneal stroma (from about 50 kPa to about 13 MPa, e.g., about 150 kPa); it is stiff enough to allow the grafting procedure; it is permeable to glucose, oxygen, and proteins; it has high water content; it is non-degradable or slow degradable and can be slowly remodeled by the body and replaced with native tissue without affecting its geometry and optical properties; it is not stimulating an immune response and can be shaped with laser processing and/or 3D printing or molding.

[0105] It is according to a few embodiments of the invention wherein the intrastromal lenticule of the present invention is prepared by various methods, including those selected from a group consisting of the following steps: mixing materials; injecting into mold and/or pressing in mold and/or 3D printing; UV and/or thermal and/or chemical casting; washing out residues; possibly additional step(s) of laser processing; coating with soaking in collagen and/or proteins and/or nutrients

[0106] It is according to a few embodiments of the invention wherein the intrastromal lenticule of the present invention is grafted by various other methods, including those selected from a group consisting steps of providing a corneal flap using a mechanical tool or PRK and/or LASIK excimer laser; providing a corneal pocket using a mechanical tool or femtosecond laser (e.g., SMILE procedure); possibly to use a designated tool and/or viscoelastic material for the insertion and alignment in the pocket.

[0107] As an example, and in a non-limiting manner, an Inlay is made by lyophilized human collagen type I, mixed in 20 mM hydrochloric acid to get 6% (w/v) collagen solution. Additional 1 to 10% v/v HEA solution is mixed with the collagen, and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) is admixed to form 0.5% (w/v) solution. The yield is thoroughly mixed and centrifuged, and poured into poly propylene (PP) contact lens molds. The molds are inserted into nitrogen chambers at 10 degrees C. for 12 to 24 hours. After crosslinking, lenticules are washed in saline for 24 to 72 hours. Washed hydrogel is then placed in an Excimer Laser system and ablated to form a lenticule with optical power according to an OCT scan of the patient's eyes. The resulting Inlay lenticule is further scanned by an OCT system to assure its optical properties, and possibly, lenticules are marked using Gentian Violet surgical marker by an arrow shaped and an “S” shaped marks, for easier grafting orientation.

[0108] Reference is now made to FIG. 3 which shows OCT scans of an intrastromal lenticule graft before and after laser processing, in accordance with a few embodiments of the present invention.

[0109] Several publications, patents, and patent applications have been cited hereinabove. Each of the cited publications, patents, and patent applications are hereby incorporated by reference in their entireties.

[0110] All of the compositions and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.