Scaffold compositions for tissue repair

Abstract

The present invention relates to hemostatic scaffold compositions and the method of preparation thereof. In present invention, hemostatic scaffold compositions for wound care and dental care, uses chitosan and tranexamic acid.

Claims

1. A hemostatic scaffold composition consisting of about 70% to about 80% of chitosan, 15% to about 25% of tranexamic acid, and about 1% to about 5% of dicalcium silicate, wherein dicalcium silicate has the particle size of about 10 nm to about 500 nm.

2. A hemostatic scaffold composition consisting of about 70% to about 80% of chitosan, 15% to about 25% of tranexamic acid and about 1% to about 5% of dicalcium silicate, wherein dicalcium silicate has the particle size of about 10 nm to about 500 nm, and wherein the hemostatic scaffold has the pore size of about 30 m to about 100 m and wherein at least 40% of tranexamic acid is released in about sixty minutes in Phosphate Buffer Saline of pH 7.4.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1: shows the image of center part of hemostatic scaffold under scanning electron microscope. The centre part of hemostatic scaffold has the pore size of about 50 m to about 70 m.

(2) FIG. 2: shows the image of cross section of hemostatic scaffold under scanning electron microscope. The cross section of hemostatic scaffold has the pore size of about 40 m to about 70 m.

(3) FIG. 3: shows the image of side view of hemostatic scaffold under scanning electron microscope. The side view of hemostatic scaffold has the pore size of about 40 m to about 60 m.

(4) FIG. 4: shows the in vitro release of tranexamic acid from scaffold, showing that 40% of the tranexamic acid is released in sixty minutes' in pH 7.4 Phosphate buffer saline.

DETAILED DESCRIPTION OF THE INVENTION

(5) The present invention is directed to hemostatic scaffold composition such as external wound scaffolds, dental scaffolds that can prevent hemorrhage, prevent microbial infections, protect burn wounds and also aid in tissue regeneration.

(6) The present invention provides the hemostatic scaffold composition comprising the hydrophilic polymer and one or more active ingredients.

(7) In one embodiment, the hemostatic scaffold compositions of the present invention comprise hydrophilic polymer. The hydrophilic polymer may be an alginate, chitosan (or its derivatives), a hydrophilic polyamine, polylysine, polyethylene imine, xanthan gum, carrageenan, Pectin, quaternary ammonium polymer, chondroitin sulfate, a starch, modified cellulosic polymer, dextran, hyaluronan or combinations thereof. Preferably, the hydrophilic polymer is chitosan. Chitosan is preferably used in the range from about 70% to about 80% of the total weight of scaffold composition.

(8) In another embodiment, the hemostatic scaffold compositions of the present invention comprise chitosan and tranexamic acid. Tranexamic acid is preferably used in the range from about 15% to about 25% of the total weight of the scaffold composition.

(9) In another embodiment the hemostatic scaffold compositions of the present invention comprise an active ingredient or combinations of active ingredients. The active ingredient may include, but is not limited to tranexamic acid and inorganic salts and combinations thereof.

(10) In a further embodiment the hemostatic scaffold compositions of the present invention comprises an inorganic salt as the active ingredient. The inorganic salt may be selected from the group consisting of hydroxyapatite, calcium sulphate, dicalcium silicate, calcium phosphate, magnesium silicate. Preferably the inorganic salt selected is dicalcium silicate. Dicalcium silicate with the particle size ranging from about 10 nm to about 500 nm is most preferably used dicalcium silicate (nano dicalcium silicate). Nano dicalcium silicate is preferably used in the range from about 1% to about 5% based on the total weight of the scaffold composition.

(11) In embodiments of the invention, tranexamic acid and the inorganic salts present in the hemostatic scaffold composition are in the ratio from about 1:100 to about 100:1. Preferably the ratio of tranexamic acid and the inorganic salts are present in the ratio from about 10:1 to 1:10.

(12) In another embodiment, the present invention provides the hemostatic scaffold compositions consisting of chitosan, tranexamic acid and dicalcium silicate.

(13) In another embodiment, the ratio of tranexamic acid to dicalcium silicate is present in the ratio of about 100:1 to about 1:100, preferably the ratio of tranexamic acid to dicalcium silicate is from about 10:1 to about 1:10.

(14) In another embodiment, the present invention provides the hemostatic scaffold compositions consisting of chitosan, Tranexamic acid and nano dicalcium silicate, wherein the particle size of nano dicalcium silicate ranges from about 10 nm to about 500 nm.

(15) In a further embodiment, the present invention provides the hemostatic scaffold composition consisting of about 70% to about 80% Chitosan, about 15% to about 25% of tranexamic acid and about 1% to about 5% of dicalcium silicate.

(16) In another embodiment, the present invention provides the hemostatic scaffold composition consisting of about 70% to about 80% Chitosan, about 15% to about 25% of tranexamic acid and about 1% to about 5% of dicalcium silicate, wherein dicalcium silicate has the particle size of about 10 nm to about 500 nm.

(17) In a specific embodiment, the present invention provides the hemostatic scaffold composition consisting of about 77% of chitosan, about 20% of tranexamic acid and about 4% of dicalcium silicate, wherein dicalcium silicate has the particle size of about 10 nm to about 500 nm.

(18) The hemostatic scaffolds of the present invention have the pore size of about 30 m to about 100 m, and further on dissolution, at least 40% of tranexamic acid is released in about sixty minutes in Phosphate Buffer Saline of pH 7.4.

(19) In embodiments of the invention, the present invention provides hemostatic scaffold composition consisting of about 70% to about 80% of chitosan, 15% to about 25% of tranexamic acid and about 1% to about 5% of dicalcium silicate, wherein dicalcium silicate has the particle size of about 10 nm to about 500 nm, and wherein the hemostatic scaffold has the pore size of about 30 m to about 100 m and wherein at least 40% of tranexamic acid is released in about sixty minutes in Phosphate Buffer Saline of pH 7.4.

(20) In specific embodiments of the invention, the present invention provides hemostatic scaffold composition consisting of about 77% of chitosan, about 20% of tranexamic acid and about 4% of dicalcium silicate, wherein dicalcium silicate has the particle size of about 10 nm to about 500 nm, and wherein the hemostatic scaffold has the pore size of about 30 m to about 100 m and wherein at least 40% of tranexamic acid is released in about sixty minutes in Phosphate Buffer Saline of pH 7.4.

(21) In the present invention, the process for preparation of hemostatic scaffold composition comprises the steps of 1. Water and acetic acid are mixed to form acetic acid solution in water 2. Chitosan solution or suspension is prepared by dissolving/dispersing the dry chitosan powder or flakes into acetic acid solution in water 3. Addition of tranexamic acid into the chitosan solution or suspension to form tranexamic acid and chitosan solution/suspension 4. To the tranexamic acid chitosan solution/suspension, nano dicalcium silicate was added to form final solution/suspension 5. Lyophilization (freeze drying) a. The suspension in step 3 is poured into trays b. Trays are loaded to the lyophilization chamber c. Then the suspension is passed through lyophilizing cycle 6. Stabilized end products are individually packaged in laminated metal pouches, which are vacuum sealed. 7. Individually packed final products are then terminally sterilized using gamma irradiation.

(22) The present invention is directed to dental scaffold compositions applied during or after a dental procedure to ameliorate bleeding, fluid seepage or weeping, or other forms of fluid loss, as well as promote healing.

(23) The present invention provides the dental scaffold composition comprising the hydrophilic polymer and one or more active ingredients.

(24) In one embodiment, the dental scaffold compositions of the present invention comprise hydrophilic polymer. The hydrophilic polymer may be an alginate, chitosan (or its derivatives), a hydrophilic polyamine, polylysine, polyethylene imine, xanthan gum, carrageenan, Pectin, quaternary ammonium polymer, chondroitin sulfate, a starch, modified cellulosic polymer, dextran, hyaluronan or combinations thereof. Preferably, the hydrophilic polymer is chitosan.

(25) The present invention provides the dental scaffold composition comprising the hydrophilic polymer and tranexamic acid.

(26) In another embodiment the dental scaffold compositions of the present invention comprise an active ingredient or combinations of active ingredients. The active ingredient may include, but is not limited to tranexamic acid and inorganic salts and combinations thereof.

(27) In a further embodiment the dental scaffold compositions of the present invention comprises an inorganic salt as the active ingredient. The inorganic salt may be selected from the group consisting of hydroxyapatite, calcium sulphate, calcium silicate, calcium phosphate, magnesium silicate. Preferably the inorganic salt selected is dicalcium silicate. The nano dicalcium silicate with the particle size ranging from about 10 nm to about 500 nm is most preferably used dicalcium silicate.

(28) In the embodiments of the invention, tranexamic acid and the inorganic salts is present the dental scaffold composition in the ratio from about 1:100 to about 100:1. Preferably the ratio of Tranexamic acid and the inorganic salts is present in the ratio from about 10:1 to 1:10.

(29) In another embodiment, the present invention provides the dental scaffold compositions consisting of chitosan, tranexamic acid and dicalcium silicate.

(30) In the specific embodiment, the ratio of tranexamic acid to dicalcium silicate is present in the ratio of about 100:1 to about 1:100, preferably the ratio of Tranexamic acid to dicalcium silicate is present in the ratio from about 10:1 to about 1:10.

(31) In another embodiment, the present invention provides the process for the preparation of dental scaffold compositions comprising the steps of 1. Dissolving/dispersing the hydrophilic polymer in a solvent to make the solution/suspension. 2. Addition of active ingredient to the hydrophilic polymer suspension/solution of step 1. 3. Addition of nano dicalcium silicate to the solution/suspension of step 1, mix and 4. freeze drying.

(32) The solvent used to dissolve the hydrophilic polymer is selected from the group consisting of acetic acid, hydrochloric acid, lactic acid. The most preferably used solvent is acetic acid.

(33) In the most preferred embodiment, the present invention provides the process for the preparation of dental scaffold compositions comprising the steps of 1. Mixing of acetic acid and water to form the acetic acid solution in water 2. Dissolving/dispersing the chitosan in acetic acid solution in water to make the chitosan solution/suspension 3. Addition of tranexamic acid to contents of step 2 to form chitosan and tranexamic acid solution/suspension 4. Addition of nano dicalcium silicate to contents of step 3 to form final solution/suspension 5. freeze drying or lyophilization.

(34) In another embodiment, a method of preventing severe bleeding in a subject comprising administering a dental scaffold composition of the present invention is provided, preferably, the subject is a mammal. More preferably, the mammal is human.

(35) In another embodiment this invention is used as a hemorrhage control for preparation of wound dressings (external wound scaffolds). The wound dressing (external wound scaffolds) for controlling severe bleeding is formed from chitosan, nano dicalcium silicate and Tranexamic acid. The wound dressing (external wound scaffolds) is being capable of substantially stanching the flow of the severe life-threatening bleeding from the wound by adhering to the wound site, to seal the wound, to accelerate blood clot formation at the wound site, to reinforce clot formation at the wound site and prevent bleed out from the wound site, and to substantially prohibit the flow of blood out of the wound site.

(36) The size of the scaffold may range between 1 cm1 cm to 5 cm5 cm depending on the site of application. Lowest dimensions of scaffolds can be used to control the bleeding in oral cavity after dental procedures while larger scaffolds could be used for controlling bleeding of external wounds. However, size does not limit the property of the scaffold, any desirable size can be used depending on the site of application.

(37) The following examples are provided to illustrate the present invention. It should be understood, however, that the invention is not limited to the specific conditions or details described in the examples below. The Examples should not be construed as limiting the invention as the examples merely provide specific methodology useful in the understanding and practice of the invention and its various aspects. While certain preferred and alternative embodiments of the invention have been set forth for purposes of disclosing the invention, modification to the disclosed embodiments can occur to those who are skilled in the art.

Example 1: Compositions and Preparation of Dental Scaffolds

(38) 2 gms of chitosan was dispersed in 97.4 gms of 0.5% w/v of acetic acid solution in water and stirred continuously until chitosan is dissolved/dispersed. While the aqueous chitosan solution/suspension was being stirred, 0.5 gms of tranexamic acid, was dissolved/dispersed into it. This was followed by the addition of 0.1 gm of nano dicalcium silicate. The suspension/solution was stirred. The resultant suspension/solution was further subjected to lyophilization process. The resultant lyophilized scaffold can be cut to different sizes and/or shapes, as desired. For example, a scaffold of diameter 2.2 cm and thickness of 0.4 cm, weighs 0.03 gm.

Example 2: Clotting Time of the Blood, Comparison of the Present Invention, with the Other Compositions

(39) TABLE-US-00001 TABLE 1 Dental Scaffold compositions Clotting time Control (only blood) 7 min 11 sec Chitosan scaffold composition 6 min Chitosan + nano dicalcium silicate (0.1%) 5 min 26 sec scaffold composition Chitosan + Tranexamic acid (0.5%) scaffold 5 min composition Chitosan + Tranexamic acid + nano dicalcium 1 min 03 sec silicate dental scaffold composition as per example-1
From the table-1; dental compositions of the present invention prepared as per the example-1 has the less clotting time of blood when compared to the other compositions.

Example 3: Compositions and Preparation of Scaffolds for External Wounds

(40) 2 gms of chitosan was dissolved/dispersed in 97.4 gms of 0.5% w/v of acetic acid solution in water and stirred continuously until chitosan is dissolved/dispersed. While the aqueous chitosan solution/suspension was being stirred, 0.5 gms of tranexamic acid, was dissolved/dispersed into it. This was followed by the addition of 0.1 gm of nano dicalcium silicate. The suspension/solution was stirred. The resultant suspension/solution was further subjected to lyophilization process. The resultant lyophilized scaffold can be cut to different sizes and/or shapes, as desired. For example, a scaffold of diameter of 6.5 cm and thickness of 1.2 cm, weighs at 1 gm. The scaffold as cut is then sterilized. Dimensions of the scaffold could be of any size and shape based on the need.

Example 4: Pore Size of Scaffolds

(41) Pore size of the scaffolds was measured by vega-3 software at different locations. Pore size of the scaffolds is important for infiltration of RBC into the scaffolds and helps in plate aggregation which will enhance the clotting ability of the scaffolds. The pore size distribution pattern of pores in the scaffold affect the water absorption and water vapor permeability of the scaffold. The scaffold of the example 3 have the pore size ranging from 30-100 m. Different views of scanning electron microscope images are present in FIGS. 1, 2 & 3.

Example 5: Swelling Property

(42) Swelling property of scaffold is estimated by using water. Initially 30 mg of the scaffold was incubated in water and wet weight of scaffolds were evaluated at two different time points (5 and 10 min). Swelling index was calculated by using the following formula
WwWo/Wo100
Swelling index of the scaffolds was in the range of 100-8000 times of its initial weight.

Example 6: In Vitro Drug Release

(43) In vitro drug release from the scaffolds was evaluated by modified method. Each scaffold was placed in 6 well cell culture plate and 5 ml of PBS (Phosphate Buffer Saline pH 7.4) was added to the each well. The total system was kept in orbital shaker at 50 rpm and samples were withdrawn at regular time intervals and subjected to HPLC analysis. Release of tranexamic acid was found to be 40% from the scaffold (example-3) in sixty minutes. The release of tranexamic acid is shown in figure