A soft tissue filling composition for injection and a method for preparing the same

Abstract

The application belongs to the technical field of biological medicine and medical cosmetology, and particularly relates to a soft tissue filling composition for injection and a preparation method thereof. 100ml of the soft tissue filling composition for injection contains 1-35g of methoxypolyethylene glycol-polycaprolactone copolymer, 0.1-20g of non-ionic surfactant, and the rest of phosphate buffer; the methoxypolyethylene glycol-polycaprolactone copolymer is an amorphous sol dispersed in a molecular / micellar level, which contains but is not limited to one or more morphologies such as spherical, rod / linear and vesicular. The soft tissue filling composition for injection overcomes the problems of short maintenance time of existing fillers, high immunogenicity risk, easy induction of nodule and inflammatory reaction, and frequent embolism, and is particularly suitable for but not limited to the filling of delicate parts such as the head and face, the eye, the tear groove, the neck, the hand dermis, and the like, which have thin skin, rich blood vessels and zero tolerance to embolism.

Description

Technical Field

[0001] This invention belongs to the field of biomedicine and medical aesthetics technology, specifically relating to an injectable soft tissue filling composition and its preparation method, particularly an injectable composition and its preparation method of a methoxy polyethylene glycol-polycaprolactone amphiphilic block copolymer (mPEG-PCL) designed based on a specific molecular weight. Background Technology

[0002] With the rapid development of the medical aesthetics industry, the market demand for soft tissue fillers continues to grow due to their effectiveness in improving facial aging issues such as wrinkles and depressions. Currently, commonly used filler materials in clinical practice mainly include hyaluronic acid, collagen, and polylactic acid (PLA) microspheres. Hyaluronic acid (HA), while having good biocompatibility, has a short duration of action (usually 6-12 months), is easily degraded by hyaluronidase in the body, requires repeated injections, and is costly in the long term. Collagen has the risk of immunogenicity due to animal-derived extraction and poor mechanical strength, also facing the problem of short duration of action. Polylactic acid (PLA) microspheres can stimulate collagen regeneration, but their large particle size (10-100μm) requires large-diameter needles for injection, causing significant pain. Furthermore, larger particle size products still have a thermodynamic tendency to aggregate and cluster after storage / injection, and their long-term stability depends on solubilizers. If accidentally injected into blood vessels, solid nanoparticles can migrate with the blood flow, posing a potential risk of particle embolism. As foreign particles, they may still be phagocytosed and encapsulated by macrophages in tissues, posing a risk of inducing local inflammation, nodules, and granulomas. Their application in thin-skinned areas such as around the eyes and tear troughs is not safe and can easily cause irreversible damage to some organs or areas. Summary of the Invention

[0003] In view of the problems of existing fillers such as short duration of action, high risk of immunogenicity, and the tendency of larger particulate products to cause nodules, inflammatory reactions and frequent embolisms, this invention provides a new injectable soft tissue filling composition and its preparation method.

[0004] This invention uses methoxy polyethylene glycol-polycaprolactone copolymer as the main material, and forms a temperature-responsive in-situ sol-gel system through solubilization with a nonionic surfactant. The injectable soft tissue filling composition of this invention is a homogeneous liquid sol before injection, and transforms into a continuous phase gel in situ at body temperature after injection, without discrete particles. Each 100ml of the injectable soft tissue filling composition contains: 1-35g of methoxy polyethylene glycol-polycaprolactone copolymer, 0.1-20g of nonionic surfactant, and the balance of phosphate buffer.

[0005] The nonionic surfactant is polysorbate 80, which does not introduce changes in ionic strength and has minimal interference with the pH and osmotic pressure of the system. The osmotic pressure of the injectable soft tissue filling composition of the present invention is 285~439 mOsm / kg (close to the isotonicity of body fluid 300 mOsm / kg), resulting in less injection pain and less tissue irritation.

[0006] In this invention, the methoxy polyethylene glycol-polycaprolactone copolymer comprises, but is not limited to, one or more of the following forms: spherical, rod / linear, and vesicular, as a molecular- or micellar-level dispersed amorphous sol. After injection, it can be better dispersed in the tissue, avoiding clumping and reducing the formation of nodules, etc.

[0007] In the methoxy polyethylene glycol-polycaprolactone copolymer, the number-average molecular weight of the polyethylene glycol block ranges from 500 to 5000 Da, and the number-average molecular weight of the polycaprolactone block ranges from 2000 to 20000 Da, representing the optimal window for thermosensitive phase transition as determined by experimental screening. This invention achieves a body temperature-responsive sol-gel phase transition by precisely controlling the molecular weight ratio of PEG and PCL segments, while maintaining the particle size of the composition at the nanoscale. This allows for the use of different needle types without causing needle blockage, reduces injection pain, and provides immediate filling after injection, avoiding the risk of free embolism or nodules caused by larger microspheres. By adjusting the PCL segment length (2k~20kDa), the degradation cycle of this invention can precisely cover 1~24 months, significantly longer than hyaluronic acid (6~12 months) and collagen. Furthermore, the degradation product is neutral 6-hydroxyhexanoic acid, avoiding the accumulation of acidic PLA / PLGA products that can induce chronic inflammation.

[0008] The pH range of the injectable soft tissue filling composition is 5 to 8.

[0009] The methoxy polyethylene glycol-polycaprolactone copolymer has a particle size of 20-100 nm.

[0010] In existing technologies, most methods increase polymer solubility through latent / co-solubilizing mechanisms. This means that most solubilizers or surfactants increase polymer solubility by altering solvent polarity to enhance the solvent's affinity for hydrophobic segments or by disrupting the hydrogen bond network of water and reducing the dielectric constant. However, the polysorbate 80 used in this invention is a surfactant-type solubilizer, and its solubility is not increased by altering the overall polarity of the solvent. In this invention, polysorbate 80, as a surfactant, has both hydrophilic and lipophilic ends. When the concentration reaches the critical micelle concentration (CMC), it automatically forms micelles with the lipophilic end facing inward and the hydrophilic end facing outward, encapsulating the hydrophobic polycaprolactone segments within the micelle core. This allows them to be "hidden" and dispersed in water, achieving molecular-level dispersion and solubilization. This invention employs an encapsulation solubilization mechanism, utilizing the specific hydrophobic interaction between the oleic acid chain of polysorbate 80 and the polyester segment of PCL, allowing the copolymer to be hydrophilically modified at the molecular level. The solubilization efficiency is far higher than that of latent / co-solubilizing mechanisms. Only 0.1% to 20% of the amount is needed to stably support polymer concentrations up to 35%, and the dispersion uniformity and long-term stability are significantly better than existing technologies.

[0011] Furthermore, the polyethylene oxide segments of Tween 80 can synergistically form a denser hydrated antifouling layer with the mPEG shell at the gel-tissue interface, further resisting non-specific protein adsorption and macrophage adhesion activation, reducing the release of pro-inflammatory factors, and forming a dual synergistic effect with the occult effect of mPEG. Subcutaneous implantation experiments in rats confirmed that only mild transient inflammation was observed after injection, with basic repair after 4 weeks, without necrosis, adhesion, calcification, granuloma, thin fibrous capsule walls, and excellent biocompatibility.

[0012] The method for preparing the injectable soft tissue filling composition includes the following steps:

[0013] (1) Add the surfactant to the phosphate buffer solution, stir evenly, then add the methoxy polyethylene glycol-polycaprolactone copolymer, and stir or vortex at 50-85℃ until the methoxy polyethylene glycol-polycaprolactone copolymer is completely dissolved and dispersed to form a homogeneous solution.

[0014] (2) The above homogenized solution is homogenized using a homogenizer, the pH value is adjusted to 5-8, filtered for sterilization, and filled in a sterile environment to obtain the soft tissue filling composition for injection.

[0015] Because the micelle solubilization system of this invention is a molecular / nanomial dispersion, it can be smoothly filtered through a 0.22 μm filter membrane for three-stage terminal filtration sterilization (0.45 μm to 0.22 μm). The 0.45→0.22→0.22 μm three-stage hydrophilic filter membrane pressure filtration is a pharmacopoeia standard sterilization filtration process that directly guarantees the product's sterility assurance level (SAL), eliminating the need for subsequent sterilization processes (such as irradiation). This significantly enhances the feasibility of industrial production while ensuring product sterility.

[0016] The injectable soft tissue filling composition of this invention is a completely particle-free sol system with fluidity close to that of a solution. It can be adapted to 27G~34G ultrafine needles and is particularly suitable for, but not limited to, filling delicate areas with thin skin, rich blood vessels, and zero tolerance for embolism, such as the face, around the eyes, tear troughs, neck, and dermis of the hands.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The soft tissue filling composition for injection described in this invention is a semi-transparent homogeneous sol before injection, without any solid particles and with excellent fluidity; after injection, under the triggering of body temperature (37°C), the polymer chain segments undergo physical cross-linking and form a continuous phase gel in situ, without discrete particles; even if it is accidentally inserted into a blood vessel, the liquid sol is rapidly diluted and flushed after entering the blood, and cannot form an effective concentration of gel in the blood vessel, thus fundamentally eliminating the possibility of particle embolism from a mechanism perspective.

[0019] (2) The injectable soft tissue filling composition of the present invention is not a discrete solid "particle", but a deformable micelle aggregate; it can spread, deform and diffuse uniformly in the tissue along with the tissue gap, and there is no "rolling aggregation" and "particle feel" of spherical particles.

[0020] (3) The osmotic pressure of the injectable soft tissue filling composition of the present invention can be precisely controlled at 285~439mOsm / kg (close to the isotonicity of body fluid 300 mOsm / kg), resulting in less injection pain and less tissue irritation.

[0021] (4) The injectable soft tissue filling composition of the present invention is a completely particle-free sol system with fluidity close to that of a solution. It can be adapted to 27G~34G ultrafine needles and is particularly suitable for filling delicate areas such as the periorbital area, tear trough, neck, and hand dermis where the skin is thin, blood vessels are abundant, and there is zero tolerance for embolism.

[0022] (5) The injectable soft tissue filling composition of the present invention is a continuous phase monolithic sol with a stable hydrolysis rate and no overall disintegration. By adjusting the PCL chain length (2k~20kDa), the degradation cycle can be precisely covered from 1 to 24 months, which is significantly longer than hyaluronic acid (6~12 months) and collagen. Moreover, the degradation product is neutral 6-hydroxyhexanoic acid, without the problem of PLA / PLGA acid products accumulating and inducing chronic inflammation.

[0023] (6) The injectable soft tissue filling composition of the present invention is non-immunogenic and non-inflammatory. The mPEG shell provides an "invisibility" effect, avoids protein adsorption, and has both hydrophilic and hydrophobic properties. Animal experiments have further verified its safety and good biocompatibility. Attached Figure Description

[0024] Figure 1 Photographs of the inner and outer sides of the skin at different time points in a subcutaneous implantation experiment on SD rats;

[0025] Figure 2 Pathological images of HE-stained tissue sections from the control group in a subcutaneous implantation experiment in SD rats;

[0026] Figure 3 Pathological images of HE-stained tissue sections from the experimental group of the subcutaneous implantation experiment in SD rats;

[0027] Figure 4 Photographs of the rabbit ear injection site on the first day after injection, where A-D are the test group and E-H are the control group;

[0028] Figure 5 Photographs of the rabbit ear injection site on the third day after injection, where A-D are the test group and E-H are the control group;

[0029] Figure 6 Photographs of the rabbit ear injection site on the fifth day after injection, where A-D are the test group and E-H are the control group;

[0030] Figure 7 Photographs of the rabbit ear injection site on the seventh day after injection, where A-D are the test group and E-H are the control group;

[0031] Figure 8 The image shows a DSA scan on the seventh day after injection (animal number 218-2 in the test group). A: Left iliac artery and femoral artery; B: Right iliac artery and femoral artery; C: Abdominal aorta; D: Renal artery; E: Carotid artery and aortic artery; F: Pulmonary artery.

[0032] Figure 9 HE staining pathological images of rabbit ear tissue from test group animals (numbers 218-1 to 218-4) on the seventh day after injection;

[0033] Figure 10 HE staining pathological images of rabbit ear tissue from control animals (numbered 218-5~218-8) on the seventh day after injection;

[0034] Figure 11 Image 1 with negative staining for TEM (100nm scale bar);

[0035] Figure 12 Image 2 for TEM negative staining (100nm scale bar). Detailed Implementation

[0036] Example 1

[0037] An injectable soft tissue filling composition, wherein each 100 ml of colloidal solution contains: 25.0 g of methoxy polyethylene glycol-polycaprolactone copolymer, 2.0 g of polysorbate 80, and the balance of phosphate buffer;

[0038] The methoxy polyethylene glycol-polycaprolactone copolymer is an amorphous sol in molecular-level / micelle-level dispersion, including but not limited to one or more forms such as spherical, rod / linear, and vesicular shapes.

[0039] In the methoxy polyethylene glycol-polycaprolactone copolymer, the number average molecular weight of the polyethylene glycol block is in the range of 2000 Da, and the number average molecular weight of the polycaprolactone block is in the range of 8000 Da.

[0040] The injectable soft tissue filling composition has a pH of 7.38 and an osmotic pressure of 314 mOsm / kg.

[0041] The methoxy polyethylene glycol-polycaprolactone copolymer has a particle size of 20~80nm.

[0042] Each liter of phosphate buffer contains 2.7 g Na2HPO4·12H2O, 0.19 g KH2PO4, and 1 g NaOH.

[0043] The method for preparing the injectable soft tissue filling composition includes the following steps:

[0044] (1) Add the surfactant to the phosphate buffer solution, stir evenly, add the methoxy polyethylene glycol-polycaprolactone copolymer, adjust the volume to 100 mL, stir continuously at 85 °C for 8 h until the methoxy polyethylene glycol-polycaprolactone copolymer is completely dissolved and dispersed to form a homogeneous solution.

[0045] (2) The above homogenized solution was homogenized using a homogenizer (5000 rpm, 10 min), and the pH was adjusted to 7.38 with phosphoric acid. Under sterile conditions, it was filtered under pressure using a three-stage hydrophilic filter membrane of 0.45 μm → 0.22 μm → 0.22 μm. The solution was then dispensed into pre-filled syringes to obtain a semi-transparent sol-like liquid with a concentration of 25% w / v (calculated as methoxy polyethylene glycol-polycaprolactone copolymer), which is the soft tissue filling composition for injection.

[0046] Example 2

[0047] An injectable soft tissue filling composition, wherein each 100 ml of colloidal solution contains: 20.0 g of methoxy polyethylene glycol-polycaprolactone copolymer, 5.0 g of polysorbate 80, and the balance of phosphate buffer;

[0048] The methoxy polyethylene glycol-polycaprolactone copolymer is an amorphous sol in molecular-level / micelle-level dispersion, including but not limited to one or more forms such as spherical, rod / linear, and vesicular shapes.

[0049] In the methoxy polyethylene glycol-polycaprolactone copolymer, the number average molecular weight of the polyethylene glycol block is in the range of 2000 Da, and the number average molecular weight of the polycaprolactone block is in the range of 12000 Da.

[0050] The injectable soft tissue filling composition has a pH of 7.16 and an osmotic pressure of 439 mOsm / kg.

[0051] The methoxy polyethylene glycol-polycaprolactone copolymer has a particle size of 40~100nm.

[0052] Each liter of phosphate buffer contains 6.8g KH2PO4 and 1.388g NaOH.

[0053] The method for preparing the injectable soft tissue filling composition includes the following steps:

[0054] (1) Add the surfactant to the phosphate buffer, stir evenly, add the methoxy polyethylene glycol-polycaprolactone copolymer, and adjust the volume to 100 mL. Stir continuously at 80 °C for 6 h until the methoxy polyethylene glycol-polycaprolactone copolymer is completely dissolved and dispersed to form a homogeneous solution.

[0055] (2) The above homogenized solution was homogenized using a homogenizer (10000 rpm, 15 min), the pH was adjusted to 7.16 with phosphoric acid, and the solution was filtered under pressure using a 0.45 μm → 0.22 μm → 0.22 μm three-stage hydrophilic filter membrane under sterile conditions. The solution was dispensed into pre-filled syringes to obtain a semi-transparent sol-like liquid with a concentration of 20% w / v (calculated as methoxy polyethylene glycol-polycaprolactone copolymer), which is the soft tissue filling composition for injection.

[0056] Example 3

[0057] An injectable soft tissue filling composition, wherein each 100 ml of colloidal solution contains: 10.0 g of methoxy polyethylene glycol-polycaprolactone copolymer, 0.5 g of polysorbate 80, and the balance of phosphate buffer;

[0058] The methoxy polyethylene glycol-polycaprolactone copolymer is an amorphous sol in molecular-level / micelle-level dispersion, including but not limited to one or more forms such as spherical, rod / linear, and vesicular shapes.

[0059] In the methoxy polyethylene glycol-polycaprolactone copolymer, the number average molecular weight of the polyethylene glycol block is in the range of 2000 Da, and the number average molecular weight of the polycaprolactone block is in the range of 2000 Da.

[0060] The injectable soft tissue filling composition has a pH of 7.09 and an osmotic pressure of 285 mOsm / kg.

[0061] The methoxy polyethylene glycol-polycaprolactone copolymer has a particle size of 20~50nm.

[0062] Each liter of phosphate buffer contains 0.19g KH2PO4 and 2.7g Na2HPO4·12H2O.

[0063] The method for preparing the injectable soft tissue filling composition includes the following steps:

[0064] (1) Add the surfactant to the phosphate buffer, stir evenly, add the methoxy polyethylene glycol-polycaprolactone copolymer, and adjust the volume to 100 mL. Stir continuously at 65 °C for 4 h until the methoxy polyethylene glycol-polycaprolactone copolymer is completely dissolved and dispersed to form a homogeneous solution.

[0065] (2) The above homogenized solution was homogenized using a homogenizer (5000 rpm, 5 min), the pH was adjusted to 7.09 with phosphoric acid, and the solution was filtered under pressure using a 0.45 μm → 0.22 μm → 0.22 μm three-stage hydrophilic filter membrane under sterile conditions. The solution was dispensed into pre-filled syringes to obtain a semi-transparent sol-like liquid with a concentration of 10% w / v (calculated as methoxy polyethylene glycol-polycaprolactone copolymer), which is the soft tissue filling composition for injection.

[0066] Comparative Example 1: Using only high concentrations of mPEG-PCL

[0067] An injectable soft tissue filling composition, wherein each 100 ml of the injectable soft tissue filling composition contains: 10.0 g of methoxy polyethylene glycol-polycaprolactone copolymer, and the balance of phosphate buffer;

[0068] Each liter of phosphate buffer contains 0.19g KH2PO4 and 2.7g Na2HPO4·12H2O.

[0069] The methoxy polyethylene glycol-polycaprolactone copolymer is an amorphous sol in molecular-level / micelle-level dispersion, including but not limited to one or more forms such as spherical, rod / linear, and vesicular shapes.

[0070] In the methoxy polyethylene glycol-polycaprolactone copolymer, the number average molecular weight of the polyethylene glycol block is in the range of 2000 Da, and the number average molecular weight of the polycaprolactone block is in the range of 2000 Da.

[0071] When methoxy polyethylene glycol-polycaprolactone copolymer is added to purified water, the polymer is difficult to disperse evenly, has very poor flowability, and aggregates and precipitates after standing overnight, making it impossible to push through a 27G needle, causing needle blockage. At the same time, the dissolved state is unstable and does not have clinical injectability.

[0072] Comparative Example 2: Screening of different PEG / PCL ratios -- PEG5k-PCL1k compositions

[0073] The injectable soft tissue filling composition was prepared according to the method described in Example 1, except that the number average molecular weight of the polyethylene glycol block in the methoxy polyethylene glycol-polycaprolactone copolymer was 5000 Da and the number average molecular weight of the polycaprolactone block was 1000 Da; the rest was the same as in Example 1.

[0074] Comparative Example 3: Screening of different PEG / PCL ratios -- PEG5k-PCL20k compositions

[0075] The injectable soft tissue filling composition was prepared according to the method described in Example 1, except that the number average molecular weight of the polyethylene glycol block in the methoxy polyethylene glycol-polycaprolactone copolymer was 5000 Da and the number average molecular weight of the polycaprolactone block was 20000 Da; the rest was the same as in Example 1.

[0076] When the PCL is too short (Comparative Example 2), the raw material properties are unstable and the structure is loose. The prepared product exhibits a layered state and is unstable, making it unsuitable for long-term shelf life. When the PCL is too long (Comparative Example 3), the prepared product has poor flowability, exhibits a paste-like consistency, and cannot be displaced, making it unsuitable for injection.

[0077] Experimental Example 1: Subcutaneous Implantation Experiment in SD Rats

[0078] Research objective:

[0079] The in vivo degradation characteristics and biocompatibility of the compositions of the present invention were evaluated.

[0080] Research Methods:

[0081] Six male SD rats (weighing 200-300g) were used. After preparing the skin on both sides of the spine on the back of the rats, 1.0 mL of the soft tissue filling composition prepared in Example 1 was injected subcutaneously using a 30G needle. A control group was set up as a blank control group, which did not receive any treatment.

[0082] Observation and material collection:

[0083] Gross observations and HE staining of tissue sections were performed at the corresponding time points.

[0084] Table 1. Subcutaneous implantation study groupings

[0085] .

[0086] Research findings:

[0087] Samples taken at different time points showed no obvious redness, swelling, ulceration, or induration at the injection site. The tissue felt soft to the touch and blended naturally with the surrounding tissue. (Reference) Figure 1 As observed from the inside and outside of the skin, in Example 1, after injection, the skin showed obvious signs of incomplete absorption within 48 hours. During the 1-2 week period, the material showed slight redness and gradually expanded. During the 4 week period, the area of ​​the material and normal tissue did not expand and tended to be stable. No granulation tissue, adhesion, calcification or other abnormalities were observed.

[0088] Pathological examination revealed no significant pathological changes in the control group samples. Compared to the control group, over time, the experimental group showed a decrease in the size of inflammatory cells, accompanied by the disappearance of edema, and an increase in collagen fibers with higher density. (See details...) Figure 2 and Figure 3 pathology.

[0089] Research conclusions:

[0090] No systemic toxicity was observed in rats. Only mild inflammation and edema were observed in local tissues, and the inflammation gradually subsided over time. After 4 weeks, the local tissues were basically repaired without necrosis, adhesion, calcification, or other adverse conditions. No obvious abnormal coagulation or rapid degradation was observed in vivo after injection of the test product. No obvious tissue abnormalities related to material residue were observed at 4 weeks. This preliminarily demonstrates that the test product has good local biocompatibility and no obvious tissue compatibility issues.

[0091] Experimental Example 2: Study on Vascular Implantation Embolization

[0092] Improper injection of fillers can lead to vascular compression or even direct injection into blood vessels, causing vascular blockage, which can trigger acute inflammatory reactions and even skin necrosis, placing a great psychological burden on patients. Based on the samples prepared in Example 1, a vascular implantation test was conducted to further verify the safety of the product.

[0093] Research objective:

[0094] The product was injected into the central auricular artery of New Zealand rabbits, and the embolism of the injection site and major blood vessels was observed to assess the in vivo safety of the composition of the present invention.

[0095] Research Methods:

[0096] Following injection of the middle auricular artery into rabbits as described in Example 1, embolism was observed, with day 7 designated as the end of the observation period. No cyanosis, abnormal limb behavior, or other symptoms of vascular embolism were observed in the ears of the animals observed daily. Photographs of the injection sites in the ears of both the experimental and control groups were taken on days 1, 3, 5, and 7 for histopathological and organ observation. Simultaneously, DSA examination was performed to check for any abnormal embolism in the blood vessels.

[0097] Table 2 Grouping of Vascular Implantation Trial Studies

[0098] .

[0099] Research findings:

[0100] See the results of the photo observation. Figures 4-7 The results showed that after the injection on the first day, the blood flow in the auricles of both the test group and the control group was unobstructed, with full and uniform blood vessel color throughout the auricle. No vascular embolism phenomena such as whitening of blood vessels, distal ischemia, or vascular occlusion and collapse were observed. Focal punctate bleeding and localized subcutaneous ecchymosis were observed at the puncture sites of the middle auricular artery in both groups. This local ecchymosis was a transient and normal mechanical injury reaction caused by the middle auricular artery puncture procedure and was not related to the injected material itself. On the third and fifth days after injection, the ecchymosis caused by the puncture shrank and showed signs of recovery. No adverse reactions such as abnormal swelling, ulceration, or abnormal coloring were observed at the puncture sites in either group. On the seventh day after injection, the injection sites returned to normal, and the auricular arteries in both groups showed continuous fullness without vascular occlusion, distal ischemia and necrosis, or other embolism-related damage. No abnormal embolism symptoms such as skin necrosis or ulceration were also observed.

[0101] Gross anatomical results showed no abnormalities at the injection site in the ear. The auricle was intact, without ulceration, defects, or dry necrosis. No obvious symptoms of ischemia, whitening, blisters, erosion, or purulent exudation due to embolism were observed.

[0102] Gross examination of the major organs—heart, liver, spleen, lungs, and kidneys—showed no obvious abnormalities in their gross morphology or color, nor any gross abnormalities such as infarction, necrosis, severe congestion, abscesses, or masses.

[0103] Seven days after injection, DSA examination was performed on both test and control animals. No abnormal embolism, such as filling defects, interruptions, or delayed contrast enhancement, was observed in the aorta, carotid artery, abdominal aorta, iliac artery, renal artery, or femoral artery. See details. Figure 8 .

[0104] For details of HE staining pathological analysis of the tissue, please refer to [link / reference]. Figures 9-10 In all experimental rabbits, the overall structure of the ear skin and cartilage tissue remained intact, and the morphology of the epidermis, dermis, and skin appendages was generally normal. In both the experimental and control groups, a small amount of endothelial cell defects and loose arrangement of the tunica media smooth muscle, accompanied by scattered smooth muscle cell vacuolar degeneration, were observed in the blood vessels. No foreign bodies were found within the blood vessel lumen. Small areas of edema and widening of the connective tissue spaces were observed around the blood vessels, with scattered infiltration of inflammatory cells such as granulocytes, lymphocytes, and macrophages in the interstitium. The degree of these changes in blood vessels and interstitium varied among individuals or was due to minor injury during sampling, primarily resulting in mild, focal, and reversible tissue reactions. No abnormal pathological findings were observed in either the experimental or control groups, including foreign bodies within the lumen, large-area full-thickness destruction of the blood vessel wall, extensive skin necrosis, severe granulomas, or persistent severe inflammatory infiltration. Overall, the safety profile was good.

[0105] Research conclusions:

[0106] In summary, after injection into the middle ear artery of rabbits, Example 1 of the present invention did not induce vascular embolism or severe local tissue irritation within the dosage and observation period of this study, and its in vivo safety was similar to that of the control substance, physiological saline.

[0107] Experimental Example 3: Detection using transmission electron microscopy

[0108] Take 10 μL of the prepared Example 1 sample and add it to a copper grid to precipitate for 1 min. Absorb the floating liquid with filter paper. Add 10 μL of 2% uranium acetate to the copper grid to precipitate for 1 min. Absorb the floating liquid with filter paper. Perform detection and imaging at 120 kV and acquire and analyze the images.

[0109] See details Figure 11 and Figure 12 The composition prepared according to Example 1 of this application shows the visible morphology under a transmission electron microscope.

[0110] The above embodiments of the present invention are only some typical representative embodiments of the present invention and are not limited to these embodiments.

Claims

1. An injectable soft tissue filling composition, characterized in that, Each 100ml of injectable soft tissue filling composition contains: 1-35g of methoxy polyethylene glycol-polycaprolactone copolymer, 0.1-20g of nonionic surfactant, and the balance of phosphate buffer; wherein the methoxy polyethylene glycol-polycaprolactone copolymer is an amorphous sol in molecular-level / micelle-level dispersion comprising, but not limited to, one or more forms of spherical, rod / linear and vesicular shapes.

2. The injectable soft tissue filling composition according to claim 1, characterized in that, The nonionic surfactant is polysorbate 80.

3. The injectable soft tissue filling composition according to claim 1, characterized in that, In the methoxy polyethylene glycol-polycaprolactone copolymer, the number average molecular weight of the polyethylene glycol block ranges from 500 to 5000 Da, and the number average molecular weight of the polycaprolactone block ranges from 2000 to 20000 Da.

4. The injectable soft tissue filling composition according to claim 1, characterized in that, The pH range of the injectable soft tissue filling composition is 5 to 8.

5. The injectable soft tissue filling composition according to claim 1, characterized in that, The osmotic pressure of the injectable soft tissue filling composition is 285~439 mOsm / kg.

6. The injectable soft tissue filling composition according to claim 1, characterized in that, The methoxy polyethylene glycol-polycaprolactone copolymer has a particle size of 20-100 nm.

7. A method for preparing the injectable soft tissue filling composition according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Add the nonionic surfactant to the phosphate buffer solution, stir evenly, then add the methoxy polyethylene glycol-polycaprolactone copolymer, and stir or vortex at 50-85℃ until the methoxy polyethylene glycol-polycaprolactone copolymer is completely dissolved and dispersed to form a homogeneous solution. (2) The above homogenized solution is homogenized using a homogenizer, the pH value is adjusted to 5-8, filtered for sterilization, and filled in a sterile environment to obtain the soft tissue filling composition for injection.

8. The use of the injectable soft tissue filling composition according to any one of claims 1-6 in medical aesthetic filling treatment products.

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