MX2013000371A - Fiber wadding for filling bone defects. - Google Patents

Abstract

A fiber wadding for filling bone defects having a flocculent three-dimensional structure is disclosed. The fiber wadding includes a plurality of fibers that contain a biodegradable resin as a principal component and a siloxane. Outside diameter of the plurality of fibers of the wadding is from about 0.05 ?m to about 30 ?m. Bulk density of the fiber wadding is about 0.005-0.3 g/cm3.

Description

FIBER GUATA TO FILL BONE DEFECTS FIELD OF THE INVENTION The present invention is concerned with bioactive materials that are useful as bone repair materials for filling bone defects and can be used in the fields such as oral or maxillofacial surgery and orthopedic surgery. More specifically the present invention is concerned with a fiber batt for filling bone defects. The fiber batt has a three-dimensional structure and comprises a bioresorbable-biodegradable resin.

BACKGROUND OF THE INVENTION Some materials, when enclosed or implanted in bone defects, react with the bone and are chemically combined directly with the bone. These materials are called bioactive materials and are further classified into surface bioactive materials, where the reaction occurs only on the surface of materials and bioresorbable materials, where the reaction occurs even inside the materials and materials are gradually replaced with the bone. Exemplary marketed surface bioactive materials include hydroxyapatite ceramics (eg, the brand name APACERAM ™ supplied: by HOYA CORPORATION, Japan) and exemplary bioresorbable materials include beta phase tricalcium phosphate ceramics (e.g., OSferion ™ brand name supplied by Olympus Terumo Biomaterials Corp., Japan).

Calcium carbonate (CaC03) and gypsum (CaS04H220) are known to be also bioresorbable. These substances, however, have low strength and hardness and are difficult to be machined. In contrast, biodegradable polymers, such as poly (lactic acid), poly (cholic acid) s > Copolymers of them and polycaprolactones are highly flexible and easy to be machined. The biodegradable polymers / however do not show osteogenic ability (bone formation ability) because their biodegradability is derived from the phenomenon that they are degraded in vivo and are discharged from them. In addition, there have been some reports that some of the biodegradable polymers can affect surrounding tissues because they are commonly degraded into lactic acid or glycolic acid after degradation and thus show acidity. Under such circumstances, research has been done to provide composite materials between these inorganic compounds and organic compounds to allow composite materials to have such osteogenic ability. as bioresorbability and also have improved mechanical properties. For example, the; Japanese Unexamined Patent Application Publication (JP-A) 2001-294673 discloses a process for the preparation of a bioresorbable material by combining a poly (lactic acid) and calcium carbonate. Specifically, this document relates to a process for synthesizing a bioresorbable material by mixing a vaterite containing calcium carbonate as the main component with a biodegradable polymeric compound such as a poly (lactic acid), such a vaterite being highly soluble in water among such carbonates of calcium. This: technique is also advantageous in that the pH is always maintained around the neutrality, because even when the poly (lactic acid) is decomposed to be acid, the · acidity is neutralized by the regulating effects of the pH of the calcium carbonate how it is dissolved. ' In this unprecedented aging society, bone defects must be cured desirably as soon as possible because it is very important to maintain and ensure the performance of chewing and exercise for the maintenance of health. In order to improve the osteogenic ability, an attempt has been made to incorporate a factor such as a bone formation inducer into a bioresorbable membrane (see Japanese Patent Application Publication without Examination (JP-A) No. H06 (1994) -319794) or a proliferation factor or a bone morphogen protein (see Japanese Patent Application Publication Unexamined (PCT Application Translation) (JP-A) 2001-519210 and Japanese Patent Application Publication Unexamined (JP-A) No 2006-187303). Nevertheless, it is difficult to manipulate these factors. Thus, demands have been made to develop a bioresorbable material that has superior bone reconstruction ability to allow the bone to self-generate more reliably and more quickly.

In view of recent trends in research and technologies for bio-related materials, the mainstream of research has shifted from a design of materials for bonding a material with bone to a design of materials for regeneration of the bone; In these investigations, the role of silicon in the formation of bone has received much attention and a variety of materials and silicon-simplified have been designed (TSURU Kanji, OGAWA Tetsuro, and OGUSHI Hajime, "Recent Trends of Bioceramics Research, Technology and Standardization ", Ceramics Japan, 41, 549-553 (2006)). For example, it has been reported that controlled release of silicon can act on cells to promote bone formation (H. Maeda, T. Kasuga, and LL Hench, "Preparation of Poly (L-lactic acid) -Polysiloxane-Calcium Carbonate Hybr | id embranes for Guided Bone Regeneration ", Biomaterials, 27, 1216-1222 (2006)). Independently, when compounds of a poly (lactic acid) with one of three types of calcium carbonates (calcite, aragonite and vaterite) are prepared and rinsed in a simulated body fluid (SBF), the poly (lactic acid) compound. with vaterite forms a hydroxyapatite that has composition and dimensions similar to bone and within a shorter time between the three compounds (H. Maeda, T. Kasuga, M. Nogami, and Ota, "Preparation of Calcium Carbonate Composite and Their Apatite -Forming Ability in Simulated Body Fluid ", J. Ceram, Soc. Japan, 112, S804-808 (2004).) These findings demonstrate that the use of vaterite that can gradually release silicon, is believed to be key to providing a material that produces a reconstruction of i faster bone.

To use a material to fill bone defects, the affected area (bone defect) is excised and a dense or porous material, which has such a size to fill the affected area sufficiently, is implanted directly there or a granular material is loaded into the area. affected To ensure bone formation, it is desirable to implant or bury such material in the affected area without a separation (clearance). However, it is not easy | process a dense or porous material to adjust the dimensions of the affected area closely. In addition, a granular material if it is charged to the affected area, often drips from the affected area after surgery (implant). These techniques are therefore susceptible to improvements.

Unintentionally, a guided bone regeneration technique using a masking membrane to cover a bone defect is also known. The technique of guided bone regeneration does not involve loading a material into the affected area. Instead, this technique uses a masking membrane that has the functions of preventing the invasion of cells and tissues not involved in the bone formation to the bone defect, allowing the ability of self-regeneration of the bone to be exhibited and help the bone to be rebuilt. This technique aims to cure the bone defect by using the curing ability that a living body inherently has. For example, Japanese Unexamined Patent Application Publication (JP-A) No. 2009-61109 discloses a guided bone generation membrane and method of production thereof, wherein the guided bone regeneration membrane has a bilayer structure including a first nonwoven fabric layer and a second nonwoven fabric layer, in which the first nonwoven fabric layer contains a silicon-releasable calcium carbonate and a biodegradable resin as main components and the second layer of non-woven fabric contains; a biodegradable resin as the main component. It has been reported that the use of this membrane gives satisfactory proliferation of murine osteoblast-like cells (MC3T3-E1 cells) and when a bone defect formed in a rabbit cranial bone is covered by such a membrane, satisfactory bone formation (osteogenesis) is observed (see, T. Wakita, A. Obata and T. Kasuga, "New Fabrication Process of Layered em bers Based on Poly (Lactic Acid) Fibers for Guided Bone Regeneration", Materials Transactions , 50 [7], 1737-1741 (2009)). This membrane, however, is not usable as a material for filling bone defects because it has a small thickness of 230 to 300 μm. furthermore, the overall density of such membranes, which is estimated to be around 0.4 g / cm 3 or more, is generally too high to be used as a material to fill bone defects.

BRIEF DECLARATION OF THE INVENCIÓ Thus, an object of the present invention is to provide a fiber batt formed of a bioresorbable material to fill bone defects, such material can have a sustained release system with such a chemical composition to guide the bone reconstruction ability effectively and has a Three-dimensional structure that has such flexibility to fit into a satisfactorily affected area.

In one aspect, the present invention is concerned with a fiber batt for filling bone defects, wherein the fiber batt has a flocculent three-dimensional structure including a plurality of fibers. The fibers contain a biodegradable resin as a main component and contain or carry a siloxane.

In one aspect, the fibers in a fiber batt of the invention can be coated with hydroxyapatite on their surface. The biodegradable resin can be poly (lactic acid) or a copolymer thereof. The fibers may contain siloxane dispersed in microparticles of calcium carbonate.

In one aspect, the present invention is concerned with a fiber batt for filling bone defects comprising a plurality of fibers comprising a biodegradable resin and vaterite phase calcium carbonate microparticles, wherein the plurality of fibers are interlaced between yes in three-dimensional directions to form a fiber batt, in such a way that the overall density of the fiber batt is 0.005-03 g / cm3.

In one aspect, the present invention is concerned with a fiber batt for filling bone defects, comprising a plurality of biodegradable fibers containing a plurality of microparticles of calcium carbonate and siloxane. The biodegradable fibers are interlaced three-dimensionally with each other to create three-dimensional spaces of around several tens: of microns or more throughout the structure of fiber batt, in such a way that the fiber batt has sufficient flexibility in all three-dimensional directions thereof without forming a flat mat structure. The overall density of the fiber batt as measured according to JIS L '1097 is about 0.005 g / cm3 to about 0.3 g / cm3.

In one aspect, the present invention is concerned with a fiber batt for filling bone defects, comprising a plurality of fibers containing a biodegradable resin, calcium carbonate microparticles of vaterite phase and siloxane. The plurality of fibers are intertwined with each other in three dimensional directions to form a fiber batt structure, such that the fiber batt has substantially the same flexibility in all three dimensional directions thereof., The overall density of the fiber batt is about 0.005 g / cm3 -0.3 g / cm3, the compressibility of the fiber batt, as measured according to JIS L 1097 is about 10% to about 55% and compression recovery of the batting of fiber, as measured according to JIS-L 1097 is about 5% to about 76%.

In one aspect, the present invention is concerned with a fiber batt for filling bone defects comprising a plurality of biodegradable fibers containing a plurality of calcium carbonate microparticles and siloxane. The biodegradable fibers are interlinked three-dimensionally with each other to create three-dimensional spaces of about several tens and one microns or more throughout the fiber batt structure, such that the fiber batt has sufficient flexibility in all three-dimensional directions of the fiber. without forming a flat mat structure. The overall density of the fiber batt as measured according to JIS L 1097 is about 0.005 g / cm3 to about 0.3 g / cm3.

In one aspect, the present invention is concerned with a fiber batt for filling bone defects comprising a plurality of fibers containing a biodegradable resin., calcium carbonate microparticles of vaterite and siloxane phase. The plurality of fibers are interwoven with each other in three-dimensional directions to form a fiber batt structure, such that the fiber batt has substantially the same flexibility in all three-dimensional directions thereof. The overall density of the fiber batt is about 0.005 g / cm3 -0.3 g / cm3, the compressibility of the fiber batt, as measured according to JIS L 1097 is about 10% to about 55 % and compression recovery of the fiber batt, as measured according to JIS L 1097 is from about 5% to about 76%. ! ; BRIEF DESCRIPTION OF THE FIGURES Other objects, elements and advantages of; the present invention will be more fully understood from the following detailed description made with reference to the appended figures. In the figures: Figure 1 shows an explanatory view of a common electrospinning technique; Figure 2 shows an explanatory view of an electrospinning technique according to an embodiment of the present invention Figure 3 illustrates the appearance of a three-dimensional structure of a fiber batt prepared in Example 1, indicated with 10 mm squares; Figure 4 shows a scanning electron micrograph (SEM) of fibers that constitute the three-dimensional structure of a fiber batt prepared in example 1; : Figure 5 is a graph showing the amounts of silicon ions released from a three-dimensional structure of Si-PLA15, prepared with example 1 to a cell culture medium; Figure 6 is one showing the amounts of silicon ions released from a three-dimensional structure of Si-PLA50, prepared with Example 1 to a cell culture medium; Figure 7 shows a scanning electron micrograph (SEM) of fibers that constitute a three-dimensional structure of Si-CaCO3 / PLA prepared in example 2; i Figure 8 shows a scanning electron micrograph (SEM) of fibers that constitute a three-dimensional structure of Si-CaCO3 / PLA obtained after rinsing in 1.5 SBF, the three-dimensional structure Si-CaCO3 / PLA prepared in Example 2; Figure 9 illustrates X-ray diffraction patterns of the three-dimensional structure of Si-CaCO3 / PLA prepared in Example 2, before and after rinsing in 1.5 SBF; Figure 10 is a graph showing the results of cell proliferation tests of a three-dimensional structure of Si-CaCO3 / PLA coated with hydroxyapatite prepared in Example 2 and a comparative sample.

Figure 11 shows a photograph of SEM of microparticles of a calcium carbonate releasable by silicon obtained by the carbonation process.

Figure 12 shows an explanatory view of an electrospin technique according to an embodiment of the present invention; Figure 13 (A) shows an explanatory view of the global density measurement of the fiber batt prepared in Example 3. Figure 13 (B) shows an explanatory view of the compressibility measurement of the prepared fiber batt in example 3 in which a bone is placed on a cover. Figure 13 (C) is an explanatory view of the measurement of the compression recovery of the fiber batt prepared in example 3, in which the weight is removed from the cover.

DETAILED DESCRICPION The present invention will be further described with reference to various embodiments in the figures. Modalities of the present invention are concerned with bioactive materials for filling bone defects. The materials comprise fiber batting. Such material has a flocculent three-dimensional structure. a fibrous substance comprising a biodegradable resin as the main component the fibrous substance contains or carries a siloxane.

As used herein, a flocculent three-dimensional (3D) structure is a loose, fluffy 3D structure. A biomaterial of the invention having such a fluffy 3D structure can be defined by various physical / chemical parameters, such as its weight, overall density, compressibility, compression recovery ability, as described herein. These physical / chemical parameters can be determined using known standard methods, such as the Japanese industrial standard methods (JIS), particularly the JIS L 1097 method.

A siloxane is any chemical compound composed of units of forms (R2SiO) n wherein R is a hydrogen atom or a hydrocarbon group (eg, methyl, ethyl, propyl and butyl). The siloxane has a fundamental chain that includes Si and O 'alternating. A siloxane suitable for use with embodiments of the invention can be any siloxane that can release SI in vivo. See, for example > Wakita et al., "Preparation of electrospun siloxane-poly (lactic acid) -vaterite hybrid fibrous membranes for guided bone regeneration," Compos. Sci. Technol. , 2010; 70: 1889-1893 ..; The bioactive materials of the invention can be prepared using electrospinning techniques. The electrospinning uses an electric charge to stretch very fine fibers (commonly on a micro or nano scale) of a liquid or a slurry. When a sufficiently high voltage is applied to a liquid drop, the liquid body is charged. The electrostatic repulsion in the drop would counteract the surface tension and the drop is stretched. When the repulsion force exceeds the surface tension, a stream of liquid erupts from the surface. This point of eruption is known as Taylor's cone. If the molecular cohesion of the liquid is high enough, the current! it does not break and a jet of charged liquid forms. As the jet dries on the fly, the current flow mode changes from ohmic to convective as the charge | | migrates to the surface of the fiber. The jet is then elongated by a process of pumping caused by the electrostatic repulsion initiated in small folds in the fiber, until it is finally deposited on a rectified collector. The elongation and thinning of the fiber resulting from this fold instability leads to the formation of uniform fibers with nanometer-scale diameters. · While the voltage is normally applied to the solution or slurry in a regular electrospinning process, according to embodiments of the present invention, the voltage is applied to the collector, not to the polymer solution (or slurry) and for Consequently, the polymer solution is ground. The polymer solution or slurry is atomized to the fibers while the voltage is applied in this way and the fibers are entangled to form a three-dimensional structure.

Alternatively, a material to fill; Bone defects having a three-dimensional structure and which is satisfactorily flexible can also be: obtained by carrying out the improved electrospinning technique, followed by rinsing the electrospinned material into a pH-regulating solution which is supersaturated with hydroxyapatite.

Examples of biodegradable resins used with embodiments of the invention include polymers; synthetics, such as polyethylene glycols (PEG), polycaprolactone (PCL), poly (lactic acids) (PLA), polyglycolic acids (PGA) and copolymers of PEG and PCL and natural polymers such as fibrins, collagen, alginic acid, hyaluronic acid, chitin and chitosan. Preferred examples of the biodegradable resin include a poly (lactic acid), (PLA) and a copolymer of a poly (lactic acid) and a [poly (glycolic acid) (PGA) (ie, copolymer of lactic acid-glycolic acid) .

According to embodiments of the invention, a material for filling bone defects can be produced in the following manner. Initially, a solution is; prepared by dissolving a biodegradable resin (such as 1 PLA) in a suitable solvent, for example chloroform: (CHC13) and / or dichloromethane. An aqueous solution of aminopropyltriethoxysilane (APTES) is added to the solution. In this method, the weight ratio of PLA: APTES (PLA to APTES) is possibly from 1: 0.01 to 1: 0.5 but is preferably from 1: 0.01 to 1: 0.05 (by weight). This is because most APTES, if added in an excessively large amount, is dissolved in premature stages of rinsing in the aqueous solution and therefore is not as effective. The PLA has a molecular weight of about 20 x 104 about 30 x 104 KDa. The concentration of the PLA in the solution is preferably from 4 to 12% by weight for satisfactory spinning. To maintain satisfactory spinning conditions, dimethyl formamide and / or methanol can be added to the solution in a proportion of about 50% by weight or less - relative to chloroform and / or dichloromethane. i A liquid having a relative dielectric constant greater than that of the biodegradable resin can be added to the resulting solution to produce a spinning solution for the preparation of a three-dimensional structure. CommonlyWhen the biodegradable resin is a poly (lactic acid), a liquid having a relative dielectric constant greater than that of lactic acid can be added. Examples of liquids having relative dielectric constant greater than that of lactic acid (relative dielectric constant: 22.0) include methanol (relative dielectric constant: 32.6), ethanol (relative dielectric constant: 24.6), ethylene glycol. (relative dielectric constant: 37.7), 1, 2-propandiolj (relative dielectric constant: 32.0), 2,3-butanediol, glycerol (relative dielectric constant: 42.5), acetonitrile (relative dielectric constant: 37.5), propionitrile (relative dielectric constant : 29.7),; benzonitrile (relative dielectric constant: 25.2), sulfolarium (relative dielectric constant: 43.3) and nitro methane (relative dielectric constant: 35.9). Any of! these are effective, but more advantageously water; (relative dielectric constant: 70 to 80) can be used.; However, the water is invisible with and completely separated from chloroform and / or dichloromethane used as a solvent: for PLA. To avoid this problem, an amphiphilic liquid, such as methanol, ethanol, propanol and / or acetone, is preferably in coexistence with the solvent and water. Such amphiphilic liquids for use herein are not limited in their relative dielectric constants, so long as they are amphiphilic and satisfactorily invisible both with the solvent (such as chloroform and / or dichloromethane) and water. As an example, 0.5 to 5 g of the amphiphilic liquid (such as methanol, ethanol, propanol and / or acetone) and 0.5 to 3 g of water can be added per 1 g of the PLA.

A spinning solution can be further combined with a calcium carbonate to form a waxy paste (spinning pulp). This helps accelerate (acceleration) the rinsing step of the electrospinned article in a solution. pH regulator that is supersaturated with hydroxyapatite to form an absorbable hydroxyapatite thereon. The absorbable hydroxyapatite helps to confer higher initial cell adhesion. The amount of carbonate I of calcium is possibly 60% by weight or less, because calcium carbonate, if added in an amount of more than 60% by weight, can be difficult to mix with the solution to give a homogenous slurry. However, calcium carbonate, if added in an amount less than 10% by weight, may not exhibit its beneficial effects noticeably. The watery solution or paste may further include one or more inorganic substances which are usable in vivo without problem. Examples of inorganic substances include hydroxyapatite, tricalcium phosphate, phosphate; of calcium, sodium phosphate, sodium hydrogen phosphate, calcium hydrogen phosphate, octacalcium phosphate, tetracalcium phosphate, calcium pyrophosphate and calcium chloride.

According to embodiments of the invention, a material for filling bone defects can also be a substance that contains a biodegradable resin as the main component and that also contains or carries a siloxane. This substance can be prepared by preparing siloxane-bearing calcium carbonate microparticles dispersed therein (Si-CaCO3), commonly by the method described in Japanese Unexamined Patent Application Publication 1 ((JP-A) No. 2008 -100878) and mix 60% or less of the Si-CaC03 microparticles with PLA. The amount of Si-CaCO3 microparticles is preferably 10 to 60% by weight relative to PLA, as in calcium carbonate. To uniformly disperse the microparticles, the substance is preferably prepared by kneading the PLA and Si-CaCO3 microparticles in predetermined proportions in a heating kneader to give a compound. The compound is then dissolved in the solvent to give a spinning solution.

According to a common electrospinning technique, as illustrated in Figure 1, a charge is applied via a voltage supply 1 to a nozzle of a syringe 2. In this manner, a positive charge is applied to a spinning solution and The solution is slowly extruded from the tip of the nozzle. When the effect of the electric field becomes larger than the surface tension, the solution is removed from fibers and travels towards a collector 3 which is connected to a ground electrode. On the way to the collector 3, the solvent in the solution evaporates, thereby forming a thin layer of non-woven fiber fabric. This technique, however, does not produce a three-dimensional structure, even if the spinning conditions are modified. (such as the concentration of the spinning solution, the type of solvent contained in the solution, the rate of supply of the solution, the spinning time, the applied voltage and the distance between the nozzle and the collector). This is because the residual solution and the resin deposited on the collector 3 are self-charged and repel each other. The repulsion prevents deposition in the thickness direction. In this connection, the fibrous resin derived from the solution deposited on the collector 3 would have the majority of the solvent evaporated. However, a trace amount of the solution is deposited intact (ie, containing the solvent) on the collector 3.

In contrast, according to the present invention, as illustrated in Figure 2, a three-dimensional structure of a fiber batt can be formed by carrying out electrospinning while the nozzle of syringe 2 is connected to ground (this is, without applying load to it). At the same time, a positive charge is applied to the collector 3. According to this technique, if a regular spinning solution is slowly extruded from the tip of the nozzle, the spinning solution would fall as drops, because the solution is not charged. However, when the spinning solution also contains a liquid, such as water, which has a relative dielectric constant greater than that of the biodegradable resin, the liquid can be affected by the electric field and the spinning solution can be stretched to the collector by the polarization action. In this case, the spinning solution is not self-loading and easily forms three-dimensional deposits on the collector 3 without suffering from electrostatic repulsion. In this process, the liquid (solution) can be divided into 2, strands and stretched from the nozzle of the syringe 2 towards the manifold 3. These strands are interlaced to form a j threedimensional structure flocculent on the collector 3.

To allow this phenomenon to occur, however, the spinning solution must have a somewhat low viscosity. If the spinning solution has an excessively high viscosity, it may not reach the collector even when affected by the electric field. Thus, the diameter of the fibrous substance constituting the three-dimensional structure prepared according to embodiments of the invention can be substantially controlled by the viscosity of the spinning solution. When the spinning solution has a particularly low viscosity, the fibrous substance can be more easily deposited to form a three-dimensional structure and the fibrous substance would more likely have smaller fiber diameters. Commonly, when a spinning solution is prepared by dissolving PLA in chloroform to give a solution, followed by the addition of ethanol and water thereto, the resulting fibrous substance has a fiber diameter in the range of about 0.05 μp? to 1 around 10 pm. it is acceptable not to apply a positive charge, but a negative charge to the collector 3, as long as the spinning solution can be drawn towards the collector by the polarization action. i The three-dimensional structure resulting from a wadding of fiber can be cut into a piece of the required size and the cut piece can be rinsed in a pH regulated solution containing calcium ions and phosphate ions and which is saturated with respect to hydroxyapatite, to: coat the surface of the fibrous shell with hydroxyapatite. Examples of the pH buffer for use herein include a Tris pH buffer (pH 7.2 to 7.4) containing ions at a concentration substantially equal to the concentration of inorganic ion in human plasma (simulated body fluid or SBF) ) and a solution (1.5 SBF) containing ions in concentrations 1.5 times those of the SBF. The SBF 1.5 is more advantageous because the fibrous substance can be coated with hydroxyapatite more quickly.

In accordance with the present embodiment, a flexible material is provided to fill bone defects,. such material has a three-dimensional structure of a wadding; of fiber including a fibrous substance, in which the fibrous substance contains a biodegradable resin, represented by poly (lactic acid) (PLA), as a main component and contains in addition or carries siloxane. A filler material for bone repair is also provided, in which the surface of the fibrous substance constituting the three-dimensional structure is coated with hydroxyapatite. Such material, which includes a communication space for the entrance of cells, and has improved adjustability in the affected area, can be easily prepared at; adapt the technique to produce a non-woven fabric by means of electrospinning for the production of: three-dimensional structure. In addition, the coating i with an absorbable hydroxyapatite can be easily effected by rinsing the electrospinned article in a pH-regulated solution supersaturated with hydroxyapatite and the absorbable coated hydroxyapatite helps to provide higher initial cell adhesion.

A fiber batt for filling bone defects thus obtained has satisfactory flexibility in all three-dimensional directions to fit a bone defect derived from the three-dimensional structure constituted by the fibrous substance. The flexibility of: the fiber batt is substantially the same in all three-dimensional directions. The fiber batt does not tend to form a flat mat structure in which the fibers are interlaced and extended in two-dimensional directions. Such fiber batt shows high cell proliferation in a cellular affinity analysis using osteoblast-like cells (C3T3-E1 cells) and is an excess in bone reconstruction ability. The overall density of the fiber batt of this embodiment is much lower than the masking membrane of the prior art, as revealed for example by JP-A 2009-61109 .. i According to some embodiments of: the present invention, the fibers of the fiber batt are formed of a silicon-lib'erablé calcium carbonate compound and a biodegradable polymer.

Similar to the exemplary embodiment discussed above, calcium carbonate microparticles of vaterite phase can be used as Si-releasable calcium carbonate, the Si content of which may be for example 2% by weight (hereinafter referred to as 2SiV). ). As disclosed in detail in the Japanese Unexamined Patent Application Publication ((JP-A) No. 2008-100878, Si-releasable calcium carbonate can be obtained by using the carbonation process, in which carbonate gas. is atomized to a suspension of a mixture of methanol, slaked lime and organic silicon compounds Figure 11 shows a SEM photograph of the calcium carbonate microparticles, which is disclosed in (JP-A) No. 2008-100878. Although the diameters of the microparticles vary and can be changed by adjusting the production conditions, the preferable diameter range of the microparticles is approximately 0.5-1.5 m.

A silicon-releasable calcium carbonate compound and biodegradable polymer can be formed by heating / etching a mixture of silicon vaterite and polylactic acid powders and a copolymer of polylactic acid and polyglycolic acid. The molecular weights of the polylactic acid or a copolymer of lactic acid and polyglycolic acid are preferably from 150000 to 300000. In order to obtain a desirable elasticity of the fiber batt, the content of 2SiV of the compound is preferable from 30-40% in weigh. This compound can be dissolved using a solvent (such as CHCL3) to obtain a spinning solution. The spinning solution thus obtained can be processed to a fiber batt using electrospinning technique.

To process the fiber batt spinning solution using electrospinning, as illustrated in Figure 12, a positive assembly is applied to the spinning solution in a state that a full collector bin, with ethanol is connected to ground. The spinning solution is then made of fibers and the electrospinned fibers are attracted and travel to the collector vessel, where the solvent of the spinning solution is evaporated in the electric field during that process. Those fibers attracted to the collector vessel are accumulated in the ethanol of the vessel to form a cotton-like structure. By changing spinning conditions (such as the density of spinning solution, solvent classes, supply rate, electrospinning time period, applied voltage, distance between the nozzle and ethanol in the collector vessel), morphology desired wadding fiber can be obtained.

The outer diameter of the fiber batt of this embodiment is preferably around 0.5 μm around 30 μm, preferably around 0.1 μm to about 20 μm and more preferably around 10 μt? at around 20 pm. the overall density of the fiber batt as measured according to JIS L 1097 is] around 0.005 g / cm3 to about 0.3 g / cm3, preferably about 0.01 g / cm3 to about O.lg / cm3, more preferably about 0.014 g / cm3 to about 0.021 g / cm3. The compressibility of the fiber batt of this embodiment is from about 10% to about 55%, preferably from about 20% to about 55%, more preferably from 29% to 55%. The compression recovery of the fiber batt of this embodiment is from about 5% to about 76%, preferably, from about 7% to about 76%, more preferably from about 44% to about 58%.

Advantages of the invention Because the fiber batt of the present invention is formed of Si-releasable calcium carbonate and a biodegradable polymer it exhibits high cell proliferation and has an excellent ability to rebuild bone. In comparison with the masking membrane the density of a fiber batt of the present invention is very low. In addition, a fiber batt of the invention is flexible and has excellent elasticity. Therefore, it can; be easily filled in bone defects during surgery and can be implanted in bone defects without separation (clearance).

EXAMPLE 1 and EXAMPLE 2 The present invention will be illustrated, in further detail with reference to several examples below which are concerned with three-dimensional structure production methods. It should be noted, however, that these examples are illustrated for a better understanding of the present invention and are never intended to limit the scope of the present invention. The skilled artisan would appreciate that various modifications are possible without departing from the scope of the invention.

Raw materials used in Example 1 and Example 2 Poly (lactic acid) (PLA): PURASORB. PL Poli (L-lactides), which has a molecular weight of 20 x 1O4 to 30 x 104, is from PURAC Biochem (a division of CSM, The Netherlands). Chloroform (CHC13 analytical grade reagent, with a purity of 99. 0% or more, is from Kishida Chemical Co., Ltd1. , Japan,? - i Aminopropyltriethoxysilane (APTES): (TSL8331, with a purity of 98% or more, GE Toshiba Silicones Co., Ltd., Japan).

Siloxane-doped calcium carbonate (Si-CaCO3): vaterite containing a siloxane in terms of a silicon ion content of 2.9% by weight and prepared by using slaked lime (Microstar T) with a purity of 96% or more; Yabashi Industries Co., Ltd., Japan), methanol (reagent analytical grade, with a purity of 99.8% or more, Kistiida Chemical Co., Ltd., Japan), APTES and carbon dioxide gas (liquefied carbon dioxide gas high purity, with a purity of 99.9%; Taiyo Kagaku Kogyo KK, Japan).

Electroheating conditions in Example 1 and Example 2 Feed speed of the spinning solution: 0.1 ml / min, Applied voltage: a voltage was applied to the plate collector at 25kV, while the nozzle was connected to ground Distance between the nozzle and the plate collector: 1.00 mm, Spinning time: around 60 minutes.

Example 1 APTES (1 g) was added to ultra pure water (0.5 g) with stirring to give a solution. The solution was added dropwise to a solution of PLA at 8% by weight: a. CHC13 to give an APTES content of 0.015 g and 0.050 g, respectively, followed by agitation. During this procedure, APTES was condensed to give a siloxane. To the resulting mixtures were added 1.5 g of ethanol and 1 g of ultra pure water to give spinning solutions. These spinning solutions were subjected to electrospinning and thereby produced three-dimensional structures which each include a fibrous substance containing a biodegradable resin as the main component and containing or carrying a siloxane (hereinafter, these spherical structures are referred to as as Si-PLA15 and Si-PLA50, respectively).

Figure 3 illustrates the appearance of the resulting three-dimensional structure (Si-PLA15). Figure 4 shows a scanning electron micrograph (SEM) of this steric structure, demonstrating that the steric structure is a flocculent structure that includes from several tens of nanometers to eight microns. The structures under this condition lost weight of 40 mg. The structures do not lose their flexibility and elasticity after they were rinsed in a cell culture medium and recovered from it.

Each of the steric structures prepared above was cut into a piece 10 mm wide, 10 mm long and 1 mm thick, rinsed in 4 ml of alpha-MEM cell culture medium, maintained at a temperature of 37 ° C. in an incubator in a 5% carbon dioxide gas atmosphere and the cell culture medium was exchanged with fresh medium on day 1, day 3 and day 5. Figures 5 and 6 show the amounts of ion release from silicon when the steric structures were dried in the cell culture medium as measured by means of inductively coupled plasma emission spectrometry. The data shows that both of the samples; (steric structures) released a large amount of silicon ions on day 1 and after that they released silicon ions in a significantly decreased amount, but continued to release silicon ions until at least on day 7. Si-PLA50 released around 6.5 ppm of silicon ions per day but I release 1 ppm less silicon ions from day 6 to day 7, showing only a slight difference from that in Si-PLA15.

Example 2 A three-dimensional structure of Si-CaCO3 / PLA was prepared by kneading PLA and Si-CaCO3 in a heating kneader at 200 ° C for 15 minutes to give a Si-CaCO3 / PLA compound containing 40% by weight of Si -CaC03; 1.67 g of the Si-CaCO3 / PLA compound are mixed with 8.33 g of CHCL3 to give a solution; 1.5 g of ethanol and 1 g of ultra pure water are added to the solution to give a spinning solution and the spinning solution is subjected to electrospinning under the conditions mentioned above.

The three-dimensional structure prepared; it has a flocculent appearance substantially the same as that shown in Figure 3 and had superior flexibility and elasticity. Figure 7 is a scanning electron micrograph (SEM) of the three-dimensional structure of Si-CaC03 / PLA demonstrating that this steric structure is a structure that includes fine fibers having diameters of about 0.1 to about 3 μt? and steric calcium carbonate particles having diameters of about 1 μ? embedded between the fibers. The fibers have small diameters and spaces (separations) between fibers are sufficiently large of about several tens of microns or more to give sufficient space to allow the cells therein. The amount of silicon ions released from this steric structure was determined by the procedure of Example 1 to find that the steric structure released silicon ions in amounts of 5.3 ppm on the day, 0.8 ppm from day 2 to day 3; 0.4 ppm from day to day 5 and 0.4 ppm from day 6 to day 7, indicating that the release in trace amounts of silicon ion continued.

The steric structure was cut to a sample piece 10 mm wide, 10 mm long and 10 mm thick, rinsed in 40 ml of SBF 1.5 and maintained at 37 ° C by i one day. The sample piece was then recovered from SBF 1.5 and observed under a scanning electron microscope (SEM), to find that a large number of aggregated particles as shown in Figure 8 precipitated and remained in spaces around several tens of microns to allow the cells to enter them. Figure 9 shows X-ray diffraction patterns of the sample piece before and after rinsing in SBF 1.5, demonstrating that peaks derived from hydroxyapatite were observed in the same piece after rinsing. These results demonstrate that the fiber surfaces constituting the three-dimensional steric structure of Si-CaCO3 / PLA can be coated with a hydroxyapatite only by rinsing the steric structure in SBF 1.5.

Figure 10 shows how cell numbers (in terms of cell numbers per 1 era2) vary after inoculation of murine osteoblast-like cells (MC3T3E1) on the hydroxyapatite-coated steric structure and on a comparative sample (Thermanox-plastic disc for cell culture). The Thermanox comparative sample had been treated on its surface! to improve cell proliferation and for use in cell culture. The data in Figure 10 demonstrate that the steric structure gives a cell growth capacity much: higher than. that of the comparative sample surface-treated and is expected as a material that is excellent in the ability to reconstruct bone. ! Conditions for the cell culture experiment Culture Cultivation using 24-cavity plate Cell type: murine osteoblast-like cells (MC3T3-E1 cells, Riken Institute for Physical and Chemical Research, Japan).

Cellular inoculation number: lxlO4 cells / cavity.

Medium: α-MEM (containing 10% fetal bovine serum). Exchange of the medium: on the day after inoculation, after this one day and one day no.

Sample piece: the 3D steric sample structure was cut to a piece 10 mm long, 10 mm wide and 10 mm thick (that is, a 10 mm cube).

Cell counting method: the measurement was made using Cell Counting Kit-8 (reagent, cell growth analytical / cellular toxicity, Laboratories Doj indo, Japan) according to the protocols attached to the reagent.

Example 3 Vaterite phase calcium carbonate (18; g) having a silicon content of 2% by weight (2SiV), and medical grade polylactic acid (42 g) were mixed and heated / kneaded at 200 ° C for 45 minutes . This is then cooled to obtain a compound (compound SiPVH), where the content of 2SiV is 30% by weight. 1 g of SiPVH thus obtained is dissolved in chloroform (9.3 g) and stirred to obtain a spinning solution. This spinning solution is charged to an electrospinning machine and the electrospinning to obtain fiber batting under the following conditions:; Electro-wire conditions Solution supply speed of; spinning: 0.2 ml / min, applied voltage: 17 kV and distance between nozzle and collector (filled with ethanol): about 20 cm, nozzle: syringe: 18 gauge.

As shown in Figure 12, the fibers accumulated in ethanol in the collector are recovered from the. manifold (Figure 12). Samples 1-4 were prepared from the fiber batt recovered from the collectors and analyzed. The overall density, compressibility and compression recovery were measured according to JIS L 1097. 1) Diameter of fibers The fiber diameters were measured using a laser microscope from eighteen points. It was found that while the diameter of each fiber so | measured variously, the range of distribution of the diameter was around 10 μ ?? - 21 μ ??. | : 2) Global density Each of the samples 1-4 (average weight: 0.055 g) was placed in a glass cylinder having an internal diameter of 22 mm. A circular glass cover having approximately the same diameter (weight: 1; .148 g) was placed on the fiber batt in the glass cylinder. The height of the fiber batt (h0) in the glass cylinder having the cover placed thereon was measured. The overall density of the fiber batt was calculated based on the volume of the fiber batt size and its weight (shown in Figure 13 (A)).; The result that although varied significantly between the samples, the global density of. each sample was as follows: sample 1:: 0.015g / cm3; Sample 2: \ 0.014 g / cm3; Sample 3: 0.018 g / cm3; and Sample 4: 0.021 g / cm3 (average: 0.017 g / cm3). 3) Compressibility and compression recovery As shown in Figure 13 (B), a weight of 9,914 g is placed on the glass cover placed in the glass cylinder. After 30 minutes elapsed, the height of the fiber batt (hi) in the cylinder was measured; of glass in that state. Since the change before and after placing the weight on the cover, the compressibility of the fiber batt was calculated using the following formula.

Compressibility (%) = (h0 - hi) / h0 x 100! The compressibility of the fiber batt of samples 1-4 thus measured was: Sample 1: 45.56%, Sample 2: 34.90%, Sample 3: 29.01% Sample 4: 37.80% (Average 3, 6.82%).

Next, as shown in Figure 13 (C), the weight is removed from the glass cover. After 30 minutes, the height of the fiber batt (h2) in the glass cylinder in that state was measured. Of the change before and after placing the weight on the cover and removing the weight of the cover, the compression recovery of the fiber batt was calculated using the following formula.

Compression recovery (%) = (h2 - hiJ / ího-!) X 100 The compression recovery of the wadding! of fiber samples 1-4 was as follows: Sample 1: 58.47%, Sample 2: 44.02%, Sample 3: 56.14%, Sample 4: 57.20% (average 53.96%).

Test method JIS L1097- 1982 (confirmed in the 2008) The Japanese Industrial Standards (JIS) publishes the standard method L1097 for testing synthetic fiber batting in 1982, which is confirmed in 2008. The test is carried out in a room with standard temperature and humidity class 2 (temperature 20 ± 2 ° C, relative humidity 65 ± 2%) according to JIS Z8703 (standard condition of test room).

Preparation of sample Pieces of the wadding of a product are taken < without packing and leaving each piece in the room for more than 8 hours. Then samples are randomly picked up for testing. ' The test samples of size 20 x 20 cm are stacked, in such a way that the mass weight thereof is around 40 g. pieces of test samples needed to carry out the tests are left in that state for about 1 hour.

The tests could include tests regarding color, specific volume (overall), compressibility (compression, recovery), fiber length and quality.

Testing method Specific volume (global density) The specific volume is measured by measuring the weight of test samples prepared as described above. A thick plate (a flat plate 20 x 20 cm in size and 0.5 g / cm3) is placed on a test piece and a weight A (2 kg) is placed on it for 30 minutes. Then, the weight A is removed and the sample is left for 30 minutes in that state. This procedure is repeated three times. After the weight A is removed and left for 30 minutes in that state, the heights of the sample at four corners are measured and an average height is obtained. The specific volume is calculated using the following formula. The sample must be made with three samples and an average of the three samples is obtained.

Specific volume (cm3 / g) = (20 x 20 x h0 / l0) / W where h0 is an average value of the height in four corners of the test sample (mm) and W is the weight of the test sample (g) the specific volume (cm3 / g) can easily be converted to overall density (g / cm3) if desired.

Compression elasticity (compressibility, compression recovery) The compression elasticity is measured by measuring the height at four corners of a test piece described above. A mass B (4 kg) is placed on it for 30 minutes. The heights in the four corners are measured. After this, the weight B is removed and the test sample is left for 3 minutes. The heights in four corners are measured .. The average values of those are obtained. Compressibility and compression recovery are calculated according to the following formula. The test is known for three samples, an average of the three samples is obtained. | Compressibility (%) = ((h0 _ hi) / h0) x 100 | Compression recovery (%) = (h2 - hx) '/ (h0 - hi) x 100 h0: average height in four corners before placing the weight B on them (mm). hi .: average height in four corners cori the weight B placed on them (mm). '; h2: average height in four corners after weight B is removed (mm).

While the foregoing description is of the preferred embodiments of the present invention, it would be appreciated by one skilled in the art that the invention may be modified, altered or varied without departing from the scope and fair meaning of the following claims.

Claims (19)

1. CLAIMS 1. A fiber batt for filling bone defects characterized in that it comprises a plurality of biodegradable fibers containing a plurality of calcium carbonate and siloxane macroparticles. wherein the biodegradable fibers are: interlaced three-dimensionally to each other to create three-dimensional spaces of about several tens.Mirias or more throughout the structure of fiber batt, so that the fiber batt has sufficient flexibility in all three-dimensional directions of it and wherein the overall density of the fiber batt, as measured in accordance with JIS L 1097 is from about 0.005 g / cm3 to about 0.3 g / cm3. 2. The fiber batt according to claim 1, characterized in that the external diameter of the plurality of biodegradable fibers is from about 0.5 to about 30 μm. 3. The fiber batt according to any of claims 1 and 2, characterized in that! The overall density of the fiber batt, as measured according to JIS L 1097, is from about 0.1 g / cm3 to about 0.1 g / cm34. The fiber batt according to any of claims 1 and 2, characterized in that: the overall density of the fiber batt, as measured according to JIS L 1097 is about 0.14 g / cm3 to about 0.21 g / cm3. 5. The fiber batt according to any of claims 1-4, characterized in that the compressibility of the fiber batt, as measured according to JIS L 1097 is from about 10% to about 55%. 6. The fiber batt according to any of claims 1-4, characterized in that the compressibility of the fiber batt, as measured according to JIS L 1097 is from about 20% to about 55%. . The fiber batt according to any of claims 1-4, characterized in that the compressibility of the fiber batt, as measured according to JIS L 1097 is from about 29% to about 55%. 8. The fiber batt according to any of claims 1-4, characterized in that the compression recovery of the fiber batt, as measured according to JIS L 1097 is about 5% at about 76% . 9. The fiber batt according to any of claims 1-4, characterized in that the recovery of the compression of the batt. fiber, as measured according to JIS L 1097 is around 7% around 10. The fiber batt according to any of claims 1-4, characterized in that the compression recovery of the fiber batt, as measured according to JIS L 1097 is from about 44% to about 58%. 11. The fiber batt according to any of claims 1-10, characterized in that the biodegradable fibers comprise poly (lactic acid) or a copolymer thereof. 12. The fiber batt according to any of claims 1-11, characterized in that the plurality of fibers are coated with hydroxyapatite. 13. a fiber batt for filling bone defects characterized in that it comprises a plurality of fibers containing a biodegradable resin, calcium carbonate microparticles of vaterite and siloxane phase, wherein the plurality of fibers are intertwined with each other in a three-dimensional direction to form a fiber batt structure, such that the fiber batt has substantially the same flexibility in all three-dimensional directions thereof and wherein the density of the fiber batt is about 0.005 g / cm3-0.3 g / cm3, the compressibility of the fiber batt, as measured according to JIS L 1097 is about 10% at about 55% and the compression recovery of the fiber batt as measured according to JIS L 1097 is about 5% to about 76%. 14. The fiber batt according to claim 13, characterized in that the outer diameter of the plurality of fibers is from about 0.05 μm to about 30 μm. 15. The fiber batt according to any of claims 13 and 14, characterized in that the external diameter of the plurality of fibers is from about 0.1 p to about 20 um. 16. The fiber batt according to any of claims 13-15, characterized in that the overall density of the fiber batt, as measured according to JIS L 1097 is from about 0.01 μm to about 0.1 g / cm 3. 17. The fiber batt according to any of claims 1316, characterized in that the plurality of fibers are coated with hydroxyapatite. 18. The fiber batt according to any of claims 13-17, characterized in that the biodegradable resin is poly (lactic acid) or a copolymer thereof. 19. The fiber batt according to any of claims 13-18, characterized in that the plurality of fibers contain siloxane dispersed in the calcium carbonate particulates of the vaterite phase.