WO2010125148A2

WO2010125148A2 - Methods for treating ocular conditions

Info

Publication number: WO2010125148A2
Application number: PCT/EP2010/055826
Authority: WO
Inventors: Catherine Blondel; Patricia Udaondo Mirete; Salvador Garcia-Delpech; Manuel Diaz-Llopis; Philippe Caron; Stéphane Le Bourhis
Original assignee: Catherine Blondel; Patricia Udaondo Mirete; Salvador Garcia-Delpech; Manuel Diaz-Llopis; Philippe Caron; Le Bourhis Stephane
Priority date: 2009-04-30
Filing date: 2010-04-29
Publication date: 2010-11-04
Also published as: WO2010125148A3; EP2424561A2

Abstract

The present invention relates to a non-surgical method for treating ocular conditions such as retinal ischemia, retinal inflammation, retinal edema, macular hole, tractional retinal detachment, tractional retinopathies, vitreous hemorrhage or tractional maculopathy or for preventing or reducing the rate of the progression of non-proliferative diabetic retinopathy to the proliferative form of diabetic retinopathy by administering intravitreally to a patient an effective amount of plasmin obtained by reaction of autologous plasminogen of said patient and urokinase. It also concerns a method of preparation of said plasmin. It also deals with devices or kits comprising urokinase, and optionally said autologous plasminogen, and uses thereof.

Description

METHODS FOR TREATING OCULAR CONDITIONS

BACKGROUND OF THE INVENTION

The eye can anatomically and functionally be divided into a small anterior chamber and a large posterior chamber. Both chambers are separated by the lens which is a transparent and biconvex body. The lens is connected with fibres to the ciliary muscle which by contraction or relaxation alters its shape and focusing power. The posterior chamber is filled with the vitreous body or humor, a transparent and viscous fluid or gel-like structure composed of a network of collagen fibres suspended in a liquid containing hyaluronic acid. Typically, the vitreous humor of a normal human eye contains approximately 99% water along with 1 % macromolecules including: collagen, hyaluronic acid, soluble glycoproteins, sugars and other low molecular weight metabolites. The vitreous humor, or vitreous, is thus a semi-solid material that fills the vitreous cavity, which is approximately the space in the eye between the lens and the retina. The vitreous is attached at its posterior face to the retina at the vitreoretinal junction along the inner limiting membrane. Surgical removal of the vitreous, vitrectomy, is sometimes necessary in order to treat certain medical diseases and/or dysfunctions of the eye. Typically, a vitrectomy involves the removal of the vitreous humor using mechanical instrumentation to detach and aspirate the vitreous from the eye while simultaneously replacing the removed vitreous with a sterile material such as a saline solution to prevent collapse of the eye. However, this type of surgery is not risk-free in addition to being technically complicated in some cases, even for expert surgeons, due to the strong adherence to the retina of the posterior hyaloid and the inner limiting membrane. Numerous studies have been conducted to develop a chemical system to separate the vitreoretinal interface without damage to the retina. To this end, plasmin, disclosed as a nonspecific protease and known for its fibrinolytic properties, is also associated with cleavage of laminin, fibronectin, and other components of the vitreoretinal juncture. It has been demonstrated that intravitreal injection of plasmin facilitates the formation of a posterior vitreous separation in rabbits. Additionally, plasmin facilitates the closure of traumatic pediatric macular holes and aids in surgical management of diabetic retinopathy. Plasmin administration and resulting vitreous liquefaction is used in management of various pathological conditions of the eye that are typically treated by at least partial removal of the vitreous humor including diabetic retinopathy, macular hole, macular pucker or intraocular infection. However, plasmin is unstable and must be utilized rapidly to minimize converting to an inactive form. U.S. patent 6,733,750 discloses a process for inducing posterior vitreous detachment for dissolving blood clots in the vitreous by introducing a composition including plasminogen and a plasminogen activator enzyme, such as urokinase or streptokinase, into the ocular cavity of the eye. Said composition is reported to induce substantially complete posterior vitreous detachment from the retina without causing inflammation, and without ERG or histologic abnormalities. Published U.S. patent application 2002/0139378 discloses a method for creating a separation of posterior cortical vitreous from a retina of the eye. The method includes the step of introducing plasmin into the vitreous humor of the eye. The plasmin may be introduced either by injection or through a sustained release device. Published U.S. patent application 2003/0113313 discloses a process for inhibiting vascular proliferation by separately introducing components into the eye to generate plasmin in the eye in amounts to induce complete posterior vitreous detachment where the vitreoretinal interface is devoid of cortical vitreous remnants. The process administers a combination of lysine-plasminogen, at least one recombinant plasminogen activator and thermolysin and a gaseous adjuvant to form a cavity in the vitreous. Published U.S. patent application 2003/0147877 discloses a process for liquefying vitreous humor of the eye. The process includes the step of delivering plasmin into the vitreous of the eye and incubating the vitreous and the plasmin together for a period of time. Plasmin may be introduced through injection or sustained release device and may be used to treat a pathological condition of the eye such as diabetic retinopathy, macular hole, macular pucker, intraocular infection or macular edema secondary to several vascular deseases including vein occlusion, uveitis, or diabetes. Said plasmin is preferably autologous human plasmin obtained more particularly by incubating autologous plasminogen with streptokinase. Published U.S. patent application 2003/0175263 discloses methods of modifying total matrix metalloproteinase (MMP) activity in the vitreous of the eye. Enzyme assisted vitrectomy procedures are also disclosed and comprise introducing plasmin into the vitreous in an amount sufficient to induce posterior detachment of the vitreous, mechanically detaching the vitreous from the eye, introducing a replacement fluid into the eye and introducing plasmin into the replacement fluid in the eye in an amount sufficient to decrease the total metalloproteinase activity in vitreous. Accordingly, there is a continuing need for an effective process for treating ocular disorders by implementing plasmin according to an effective and least expensive manner that comprises activating human plasminogen with urokinase (in particular urokinase 1500 to 2000 IU - IU stands for International Units) and more specifically without any side-effect, such as retinal tears, uveitis, eye inflammation or high intraocular pressure. Streptokinase is a non human medication which can produce important inflammation and high intraocular pressure in the eye after using it to activate the plasminogen in humans. Some other techniques clarify first with chromatography and spectophotometry the plasminogen but these are very expensive techniques not available for everyone. The present invention provides a very simple method which allows saving money and time with the same efficacy. SUMMARY OF THE INVENTION

This invention provides a non-surgical method for treating ocular conditions such as retinal ischemia, retinal inflammation, retinal edema, macular hole, tractional retinal detachment, tractional retinopathies, vitreous hemorrhage and tractional maculopathy or for preventing or reducing the rate of the progression of nonproliferative diabetic retinopathy to the proliferative form of diabetic retinopathy by administering intravitreally to a patient an effective amount of plasmin obtained by reaction of autologous plasminogen of said patient and urokinase. It also concerns a method of preparation of said plasmin. It also deals with devices or kits comprising urokinase, and uses thereof.

The invention also provides a composition comprising an effective amount of plasmin for use in a method for treating ocular conditions in a patient, such as retinal ischemia, retinal inflammation, retinal edema, macular hole, tractional retinal detachment, tractional retinopathies, vitreous hemorrhage and tractional maculopathy or for preventing or reducing the rate of the progression of nonproliferative diabetic retinopathy to the proliferative form of diabetic retinopathy, wherein said plasmin is obtained by reaction of autologous plasminogen of the patient and urokinase. The method according to the invention is preferably a non-chirurgical method and the composition is to be administered intravitreally to the patient.

In a particular embodiment of the composition of the invention, the autologous plasminogen is a plasminogen containing fraction obtained from human blood of the patient to be administered plasmin.

In a further particular embodiment of the composition of the invention, the effective amount of plasmin is equivalent to about 1.05 ± 0.12 IU/1 ml. More specifically, the administered effective amount of plasmin is about 0.21 ± 0.024 IU. In a particular embodiment of the composition of the invention, the plasmin is prepared by reaction of venous blood or plasma of the patient to be treated with urokinase, the plasmin obtained thereby being injected into the vitreous.

In a particular embodiment of the composition of the invention, urokinase to be reacted with autologous plasminogen is in an amount of at least about 1000 IU and less than about 3000 IU.

In another particular embodiment of the composition of the invention, the composition is co-administered with an anti-inflammatory compound.

In a specific embodiment, the anti-inflammatory compound is dexamethasone.

The invention further provides to a method of preparation of plasmin by reaction of autologous plasminogen with urokinase.

This invention also provides a kit for administering plasmin to the vitreous of a subject, comprising:

(i) at least one means for injecting the plasmin into said vitreous,

(ii) at least one device containing urokinase, preferably presenting graduation(s), (iii) optionally, a means for the reaction of the composition comprising urokinase and autologous plasminogen, preferably presenting graduation(s), (iv) optionally, a means to introduce therein autologous plasminogen, such as a collection tube, preferably presenting graduation(s), and (v) optionally, a means for sensing when the needle has been inserted to a sufficient depth to commence injection of the plasmin into the vitreous. LEGENDS TO THE FIGURES

Figure 1 : Angiography before (A) and after (B) the intravitreal injection of autologous plasmin according to the invention. Optical Coherence Tomography (OCT) before (C) and after (D) intravitreal injection of autologous plasmin according to the invention (same patient). Progression of the vitreous detachment is noticeable.

Figure 2: Angiography before (A) and after (B) the intravitreal injection of autologous plasmin according to the invention. Optical Coherence Tomography (OCT) before (C) and after (D) intravitreal injection of autologous plasmin according to the invention (same patient with vein occlusion). Progression of the vitreous detachment and reduction of edema are noticeable.

Figure 3: Means (ii) and (iii) of a kit according to the invention, comprising a pre- filled capsule containing urokinase, and optionally presenting graduation(s), and a plasmin incubator for the reaction of the composition comprising urokinase and autologous plasminogen.

DETAILED DESCRIPTION OF THE INVENTION

METHOD OF TREATMENT

This method of treatment may be practiced prior to removal of the vitreous (ie vitrectomy) or preferably without vitrectomy thereafter. The method according to the invention can therefore be used as an alternative of the surgical treatment. Accordingly, a "non surgical method" according to the invention is a method for treating ocular conditions without vitrectomy.

The plasmin used according to the method of the invention is obtained by reaction of autologous plasminogen of said patient and urokinase. More specifically, the autologous plasminogen is a plasminogen containing fraction obtained from human blood of the patient to be administered plasmin. More preferably, said fraction is plasma obtained from human blood of the patient to be administered plasmin. In a preferred embodiment, the plasmin is prepared by reaction of the venous blood or plasma of the patient to be treated with urokinase, and then the plasmin obtained thereby is injected into the vitreous.

Plasmin is preferably produced just prior to injecting so that it is desirable to introduce the obtained plasmin into the vitreous of the eye immediately after mixing autologous plaminogen and urokinase to minimize conversion of the plasmin to an inactive form. Since the obtained plasmin is preferably injected just after its preparation, the autologous plasminogen and urokinase are more specifically used in effective amounts to stimulate the conversion of autologous plasminogen to plasmin and to induce posterior vitreous detachment by the obtained plasmin.

Accordingly, the amount of the plasminogen can vary depending on various factors. For example, low levels of plasminogen will produce low levels of plasmin and therefore induce a slow rate of posterior vitreous detachment where the plasmin remains in the eye for long periods of time. Alternatively, high doses of plasminogen can be used to produce a high level of plasmin and consequently to induce a rapid posterior vitreous detachment. For example, plasminogen at doses of 4 casein units and 6 casein units can react with urokinase to produce plasmin to be introduced into the vitreous which will induce posterior vitreous detachment in several hours.

The obtained plasmin is preferably administered intravitreally in an amount sufficient to create a posterior vitreal detachment, preferably without surgery, more specifically equivalent to about 1.05 ± 0.12 IU/1 ml, which corresponds to an administered amount of about 0.21 ± 0.024 IU, since 0.2 ml is preferably the volume of the solution containing plasmin injected by eye according to the invention.

Urokinase is preferably in an amount of at least about 1000 IU/0.2ml and less than about 3000 IU/0.2 ml, in particular less than 2000 IU/0.2ml. In preferred embodiments, urokinase is used in an amount of about 1500 IU to 2500 IU/0.2 ml, in particular in an amount of about 1500 IU/0.2 ml. This dosage has been found effective in converting the plasminogen to plasmin in an effective amount and is also effective in inducing posterior vitreous detachment without causing inflammation. It has been found that a dose of 2000 IU or more can cause inflammation of the retina in rabbit eyes. In human eyes, amounts of 2500 IU of urokinase have been injected without inducing any side effect in the treatment of vitreous hemorrhages (injected volume = 0.1 ml).

The patient is the one suffering from one or more of the above mentioned ocular conditions to reduce retinal ischemia, retinal inflammation, retinal edema, macular hole, tractional retinal detachment, tractional retinopathies, vitreous hemorrhage, tractional maculopathy, diabetic retinopathy, or any combination of these conditions (including all of them).

The method can be practiced by intravitreally administering plasmin by injection, or through a cannula. A particular form of intravitreal administration is injection at multiple locations within the vitreous cavity. A more preferred form of intravitreal administration is injection in close proximity to the target tissue. A most preferred form of intravitreal administration is injection into the mid-vitreous (in particular while the head of the patient faces upward). The method can be practiced by intravitreally administering the plasmin by injection of a solution containing said plasmin and optionally an injectable aqueous solution, more particularly by injection of a solution containing plasmin and at least one other compound which cause the solution to be substantially hypotonic, isotonic, or hypertonic and/or of a pH range of 4.5-9.0 which is non toxic for injection into the eye.

METHOD FOR PREPARING PLASMIN

According to a particular embodiment, the invention also relates to a process for preparing plasmin by reaction of autologous plasminogen with urokinase. More specifically, the autologous plasminogen is a plasminogen containing fraction obtained from human blood of the patient to be administered plasmin. More preferably, said fraction is plasma obtained from human blood of the patient to be administered plasmin. In a preferred embodiment, the plasmin is prepared by reacting the collected venous blood or plasma of the patient to be treated with urokinase. More specifically, blood is extracted from the patient to be treated, and serum is recovered from the extracted blood, for instance, by centhfugation and optionally followed by filtration.

Since the obtained plasmin can be injected directly after its preparation, the autologous plasminogen and urokinase are more specifically used in effective amounts to stimulate the conversion of autologous plasminogen to plasmin and to induce posterior vitreous detachment by the obtained plasmin. The obtained plasmin is preferably administered intravitreally in an amount sufficient to create a posterior vitreal detachment, preferably without surgery, more specifically 1.05±0.12 IU/1 ml, which corresponds to a final concentration of about 0.21 ± 0.024 IU/0.2 ml of plasmin injected into the vitreous. The volume of solution to be injected is more preferably 0.2 ml per eye. Urokinase is preferably in an amount of at least about 1000 IU (International Units) and less than about 3000 IU, preferably less than about 2000 IU. In preferred embodiments, urokinase is used in an amount of about 1500 IU. This dosage has been found effective in converting the plasminogen to plasmin in an effective amount and is also effective in inducing posterior vitreous detachment without causing inflammation.

Urokinase can be any urokinase available on the market. More preferably, it can be urokinase sold under the name Urokinase (100000 IU or 250000 IU) by Vedim ® Company. Reactants (urokinase and plasminogen) may be mixed and maintained thereafter at body temperature (about 37°C), generally for several minutes, preferably from 1 to 5 minutes. Preferably, reactants are mixed at body temperature (about 37°C) and preferably injected immediately to ensure a better efficacy of the enzyme. Without being bound to any theory, it seems that the maximal efficacy of the plasmin enzyme occurs about 10 minutes after the reactants are mixed. Plasmin is preferably injected in the vitreous less that 10 minutes after the reactants are mixed to ensure a maximal benefit.

In an embodiment, plasmin is co-administered with an anti-inflammatory compound, preferably a steroidal anti-inflammatory compound, in particular dexamethasone. The term "co-administered" means the simultaneous, separate or sequential administration of both compounds to the same eye of a patient, over a period that may be up to 2 hours, or even up to 12 hours. The antiinflammatory compound is preferably added to the plasmin composition before injection. The amount of injected anti-inflammatory compound, preferably dexamethasone, is preferably 0.04 mg.

In a preferred embodiment, the injected mixture contains 0.19 ml of autologous plasmin and 0.01 ml of anti-inflammatory compound (at a concentration suitable for the intended anti-inflammatory effect), preferably steroidal anti-inflammatory compound, in particular dexamethasone (preferably 0.01 ml at 4 mg/ml). Such association may potentiate the therapeutical effects of plasmin.

Sterilization of the obtained plasmin containing solution is preferably carried out, generally by filtration, more particularly with filter of 0.22μ (Millipore). In particular, such filtration can be performed with a filter inserted between the syringe and the needle used for injection. In an embodiment, plasmin is injected at body temperature, between 35°C and 40⁰C, in particular about 37°C.

The present invention also deals with the method of preparation of said plasmin as defined above (i.e. prior to injection). It also relates to the plasmin obtainable or prepared by said method and uses thereof.

KITS

The present invention also relates to a kit which may be used in the delivery method according to the invention. Plasmin is unstable and must be utilized rapidly to minimize converting to an inactive form. In embodiments of the invention, the autologous plasminogen after extraction must be in contact with urokinase in a suitable device, optionally pre-filled with urokinase, prior to injecting the plasmin into the vitreous of the eye. The means containing both the autologous plasminogen and urokinase will produce plasmin just prior to injecting so that it is desirable to introduce the plasmin obtained from said means into the vitreous of the eye immediately after mixing to minimize conversion of the plasmin to the inactive form. In further embodiments of the invention, the autologous plasminogen and urokinase can be introduced into means so that delivery of the obtained plasmin to the vitreous of the eye can be implemented directly after preparation thereof. Alternatively, the obtained plasmin is introduced after its preparation to a common delivery device. Typically, the delivery device is a syringe or catheter with needle suitable for injecting materials into the eye.

An object of the present invention thus relates to a kit for administering plasmin to the vitreous of a subject, suitable for implementing the method according to the invention, comprising:

(i) at least one means for injecting the plasmin into said vitreous, (ii) at least one device containing urokinase, preferably presenting graduation(s), (iii) optionally, a means for the reaction of the composition comprising urokinase and autologous plasminogen, preferably presenting graduation(s), (iv) optionally, a means to introduce therein autologous plasminogen, such as a collection tube, preferably presenting graduation(s), and (v) optionally, a means for sensing when the needle has been inserted to a sufficient depth to commence injection of the plasmin into the vitreous.

The means (i) to inject the obtained plasmin might be any means familiar to the expehmentator skilled in the art. More particularly, means (i) is an injection needle, an injection needle electrode, or a combination thereof. Said means are generally used with any means familiar to the experimentator skilled in the art, such as a catheter, a syringe, etc. Typically, the delivery device is a syringe or catheter with needle suitable for injecting materials into the eye. It generally presents graduation(s) on the surface thereof so that the amount of introduced plasmin can be measured.

The kit further comprises at least one means (ii) containing urokinase. Said means can be made of any type of materials, including plastics and preferably glass, and any other biocompatible material. It could be a tube. Said means contains urokinase inside, as defined above. More particularly, said means contains an effective amount of urokinase as defined above. According to a further embodiment, said means comprises a suitable ophthalmic carrier. Said suitable ophthalmic carrier comprises preferably at least one compound which causes the solution to be substantially hypotonic, isotonic, or hypertonic and/or of a pH range of 4.5-9.0 which is non toxic for injection into the eye. An ophthalmic carrier is any vehicle support or solution suitable for the eye and also suitable for injection into the eye. Said means preferably presents graduation(s) on the surface thereof so that the amount of compounds contained and/or introduced therein can be measured. The amount of urokinase comprised in means (ii) can be the efficient amount of urokinase to be reacted with plasminogen to obtain the desired amount of plasmin to be injected in one eye or jn two eyes, or a higher amount. In an embodiment, urokinase is comprised in means (ii) as a solution of urokinase in a suitable ophthalmic carrier, i.e. in liquid form. In another embodiment, urokinase is comprised in means (ii) as a powder comprising urokinase, and optionally at least one solid excipient. Urokinase powder may be dissolved (or suspended) in the appropriate amount of a suitable ophthalmic carrier before being mixed with plasma. According to this alternative, the kit of the invention can further comprise a container containing the ophthalmic carrier to be added to urokinase before mixing with plasma. Urokinase powder may alternatively be mixed directly with plasma. The solid excipient may be for instance a chemical agent improving the stability of the powder, or a chemical agent improving the solubility of urokinase in the ophthalmic carrier or in plasma.

According to a specific embodiment, the kit also comprises a means (iii) for implementing contact of urokinase with autologous plasminogen, preferably said means presenting graduation(s). Said means can be made of any type of materials, including plastics and preferably glass. It could be a tube. Said means preferably presents graduation(s) on the surface thereof so that the amount of compounds contained and/or introduced therein can be measured.

According to another embodiment, means (ii) containing urokinase corresponds to the means where contact of urokinase with autologous plasminogen occurs. Alternatively, the means (iv) where autologous plasminogen is introduced and/or collected is the means where contact of urokinase with autologous plasminogen occurs.

Said means (iv) where autologous plasminogen is introduced and/or collected can be made of any type of materials, including plastics and preferably glass. It could be a tube, or preferably a collection tube.

The kit may further comprise a means (v) for sensing when the needle has been inserted to a sufficient depth to commence injection of the composition into the vitreous. One can choose when to commence injection of the composition according to the invention. Ideally, injection is commenced when the tip of the needle has reached the vitreous of the eye and the device preferably includes a means for sensing when the needle has been inserted to a sufficient depth for injection of the composition to commence. This means that injection of the composition can be prompted to commence automatically when the needle has reached a desired depth (which will normally be the depth at which vitreous is located).

The depth of insertion of the needle can further be recorded if desired and could be used to control injection of the plasmin such that the amount of plasmin to be injected is determined as the depth of needle insertion is being recorded.

In an embodiment, at least one of the means (i) to (iv) of the kit according to the invention additionally comprises an anti-inflammatory compound, preferably a steroidal anti-inflammatory compound, in particular dexamethasone. The amount of anti-inflammatory compound, in particular dexamethasone, may be such that an amount of 0.04 mg of anti-inflammatory compound is administered per eye.

In a preferred embodiment, the kit comprises, as means (ii) and (iii),

- a pre-filled capsule containing urokinase, and preferably presenting graduation(s), and

- a plasmin incubator : a device with pre-tuned parameters to prepare the injectable solution containing urokinase and autologous plasminogen, optionally affording stirring means.

An example of such means (ii) and (iii) is presented on figure 3. The following examples illustrate how the invention may be used for non- surgically preventing or reducing the rate of the progression of non-proliferative diabetic retinopathy and/or for treating other ocular conditions. Examples

Example 1 : Preparation and administration of plasmin

The steps to produce plasmin were performed as follows:

- 7ml of blood were extracted from the blood patient. The coagulation tube containing said blood was centrifugated at 4000 rpm for 15 minutes;

- 1.8 ml of the obtained plasma was mixed with 0.2 ml urokinase (Urokinase Vedim, 100000 IU), then mixed vigorously 2-3 minutes and then maintained by incubation at 37°C before use thereof;

- Sterilization of the obtained plasmin containing solution was performed by filtration with a filter of 0.22μ (Millipore).

Injection was performed into the eye in an amount of 0.2ml immediately thereafter.

Results of this experiment are shown in figures 1 and 2.

Example 2: Preparation and administration of plasmin in presence of dexamethasone

The steps to produce the injected mixture were performed as follows:

- 0.2 ml of the obtained plasma was mixed with 0.03 ml of urokinase (Urokinase Vedim, 250000IU) and 0.01 ml of dexamethasone (comprising 0.04 mg of dexamethasone) in an incubator at 37⁰C.

Injection was performed into the eye in an amount of 0.24 ml less than 5 minutes after the mixing step.

Similar results to those obtained for example 1 and represented on figures 1 and 2 were obtained.

Claims

1. A composition comprising an effective amount of plasmin for use in a method for treating ocular conditions in a patient, such as retinal ischemia, retinal inflammation, retinal edema, macular hole, tractional retinal detachment, tractional retinopathies, vitreous hemorrhage and tractional maculopathy or for preventing or reducing the rate of the progression of non-proliferative diabetic retinopathy to the proliferative form of diabetic retinopathy, wherein said plasmin is obtained by reaction of autologous plasminogen of the patient and urokinase.

2. The composition according to claim 1 , wherein the method is a non-chirurgical method and wherein the composition is to be administered intravitreally to the patient.

3. The composition according to claim 1 or 2, wherein the autologous plasminogen is a plasminogen containing fraction obtained from human blood of the patient to be administered plasmin.

4. The composition according to claim 1 or 2, wherein the effective amount of plasmin is equivalent to about 1.05 ± 0.12 IU/1 ml.

5 The composition according to claim 1 or 2, wherein the administered effective amount of plasmin is about 0.21 ± 0.024 IU.

6. The composition according to claim 1 or 2, wherein the plasmin is prepared by reaction of the venous blood or plasma of the patient to be treated with urokinase, the plasmin obtained thereby being injected into the vitreous.

7. The composition according to claim 1 or 2, wherein urokinase to be reacted with autologous plasminogen is in an amount of at least about 1000 IU and less than about 3000 IU.

8. The composition according to claim 1 or 2, wherein the composition is coadministered with an anti-inflammatory compound.

9. The composition according to claim 8, wherein the anti-inflammatory compound is dexamethasone.

10. A method of preparation of plasmin by reaction of autologous plasminogen with urokinase.

11. A kit for administering plasmin to the vitreous of a subject, comprising:

(i) at least one means for injecting the plasmin into said vitreous,

(ii) at least one device containing urokinase, preferably presenting graduation(s), (iii) optionally, a means for the reaction of the composition comprising urokinase and autologous plasminogen, preferably presenting graduation(s), (iv) optionally, a means to introduce therein autologous plasminogen, such as a collection tube, preferably presenting graduation(s), and (v) optionally, a means for sensing when the needle has been inserted to a sufficient depth to commence injection of the plasmin into the vitreous.

12. A kit according to claim 11 , wherein urokinase is comprised in means (ii) as a solution of urokinase in a suitable ophthalmic carrier.

13. A kit according to claim 11 , wherein urokinase is comprised in means (ii) as a powder comprising urokinase, and optionally at least one solid excipient.

14. A kit according to claim 11 , wherein means (ii) and (iii) are a pre-filled capsule containing urokinase and presenting graduation(s), and a plasmin incubator.