Skin rejuvenation composition and preparation method thereof

Abstract

The present invention relates to a composition for skin rejuvenation comprising poly-D,L-lactic acid (PDLLA) microspheres coated with poloxamer, a method of preparation thereof, and a method of improving the skin using the same. The composition of the present invention exhibits high biocompatibility, yet it can also demonstrate excellent effects on skin rejuvenation and improvement by increasing the density of fibroblasts, promoting collagen regeneration, and enhancing the amount of elastic fibers.

Description

SKIN REJUVENATION COMPOSITION AND PREPARATION METHOD THEREOF

[0001] The present invention relates to a composition for skin rejuvenation comprising poly-D,L-lactic acid (PDLLA) microspheres coated with poloxamer, a method of preparation thereof, and a method of improving the skin using the same.

[0002] The skin, being the organ most intimately connected to the external environment in the human body, serves the crucial function of protecting the body's internal organs. It comprises the epidermis, dermis, and hypodermis. Within the dermis layer, a combination of elastic solid substances (fibers) and viscous liquid substances maintains the skin's unique elasticity. Aging, stress, and other factors can lead to a decrease in the number of skin cells or skin thickness, or deformation of elastic fibers, resulting in diminished skin elasticity or the formation of wrinkles.

[0003] Research and development efforts continue for fillers and mesotherapy to address skin wrinkles.

[0004] The substances used in dermal fillers and mesotherapy are preferred to have slow degradation rates to ensure prolonged effects. Biodegradable polymers such as polycaprolactone (PCL), polylactic acid (PLA), poly-L-lactic acid (PLLA), poly-D, L-lactic acid (PDLLA), among others, are utilized, and their degradation rates vary depending on factors such as molecular weight, hydration, crystallinity, and composition. Research into materials that exhibit high biocompatibility, minimizing side effects while demonstrating rapid and superior collagen regeneration and skin improvement effects, is continuously demanded due to the varying side effects and effects of fillers and mesotherapy agents based on these factors.

[0005] The technical problem to be solved by the present invention is to provide a skin rejuvenation composition comprising poly-D,L-lactic acid (PDLLA) microspheres coated with poloxamer.

[0006] Also, the technical problem to be solved by the present invention is to provide a method for the preparation of the skin rejuvenation composition.

[0007] Also, the technical problem to be solved by the present invention is to provide a skin improvement method using the composition for skin rejuvenation.

[0008] According to an aspect of the present invention relates to a skin rejuvenation composition comprising poly-D,L-lactic acid (PDLLA) microspheres coated with poloxamer; and low molecular weight hyaluronic acid.

[0009] In the present invention, "skin rejuvenation composition" encompasses both skin fillers and mesotherapy. Skin fillers are used to restore facial volume and contours by mixing cross-linked hyaluronic acid, collagen, or carboxymethylcellulose with polyester micro-particles, and they are also used to improve facial features such as smoothing wrinkles and enhancing areas like cheeks and lips. Mesotherapy involves injecting a mixture of proven effective drugs, vitamins, minerals, amino acids, etc., into the mid-layer of the skin. Mesotherapy stimulates collagen production in the skin and improves skin hydration. Unlike traditional filler injections, mesotherapy needles are small and thin, which may lead to needle blockage due to the phenomenon of "lead block needles" when particles are large or not adequately dispersed. This phenomenon makes injection of active ingredients difficult, leading to ineffective skin improvement.

[0010] The skin rejuvenation composition of the present invention significantly improves the efficiency of injection into the skin without precipitation or aggregation of microspheres, even at high concentrations, by coating the microspheres with poloxamer, thereby enhancing their high dispersibility.

[0011] In the present invention, the 'poloxamer' refers to a polyethylene -polypropylene glycol copolymer, and the average number of polyoxyethylene and polyoxypropylene units varies depending on the polymer-associated units. For example, a poloxamer may have the following structure, and in the structure below, x and y are integers greater than 0.

[0012] [Structural Formula]

[0013]

[0014] Specifically, the poloxamer is selected from the group consisting of poloxamer 101, 105, 108, 122, 123, 124, 181, 182, 183, 184, 185, 188, 212, 215, 217, 231, 234, 235, 237, 238, 282, 284, 288, 331, 333, 334, 335, 338, 401, 402, 403 and 407, but is not limited to.

[0015] Specifically, the poly-D,L-lactic acid (PDLLA) microspheres may be contained in an amount ranging from about 0.005 %(w / v) to 0.05 %(w / v) based on the total weight of the composition, but is not limited to. Preferably, it may be contained in an amount ranging from about 0.007% (w / v) to 0.05% (w / v) based on the total weight of the composition, and more preferably, it may be contained in an amount ranging from about 0.01% (w / v) to 0.05% (w / v), but is not limited to.

[0016] Specifically, the poly-D,L-lactic acid (PDLLA) microspheres and poloxamer can be mixed at a weight ratio of 1:5 to 15, but is not limited to Preferably, they can be mixed at a weight ratio of 1:7 to 12, and more preferably, at a weight ratio of 1:9 to 11, but is not limited to.

[0017] In the present invention, the 'hyaluronic acid' is one of the major components of various extracellular matrices in the body and is abundantly present in the dermis. It has been used as one of the ingredients in traditional fillers. Hyaluronic acid is classified into low molecular weight (0.5 to 50 kDa) and high molecular weight (over 600 kDa) based on its molecular size. Low molecular weight hyaluronic acid has higher skin absorption rates and lower moisture retention, while high molecular weight hyaluronic acid has lower skin absorption rates but higher moisture retention. Therefore, high molecular weight hyaluronic acid is commonly used in cosmetic procedures such as fillers.

[0018] In one experimental embodiment, it has been observed that the dermal filling composition of the present invention, which includes low molecular weight hyaluronic acid, exhibits excellent effects on skin rejuvenation and improvement. This is achieved by increasing the skin absorption rate, while also enhancing the density of fibroblasts, collagen regeneration, and the amount of elastic fibers.

[0019] Specifically, the molecular weight of the low molecular weight hyaluronic acid may range from 0.1 to 20 kDa. Preferably, the molecular weight of the low molecular weight hyaluronic acid may range from 0.5 to 10 kDa, and more preferably, it may range from 0.5 to 5 kDa, but is not limited to these ranges.

[0020] Specifically, the low molecular weight hyaluronic acid may be contained in an amount ranging from about 0.5 to 10 %(w / v) based on the total weight of the composition, but is not limited. Preferably, it may be contained in an amount ranging from about 0.5 to 7 %(w / v) based on the total weight of the composition, and more preferably, it may be contained in an amount ranging from about 1 to 5 %(w / v), but is not limited to.

[0021] The skin rejuvenation composition of the present invention may be administered by injection, but is not limited to. Preferably, the injection may be administered subcutaneously or intramuscularly, and more preferably, it may be administered to the epidermis or dermis layer of the skin, but is not limited to. As needed, it can be administered through appropriate routes.

[0022] Specifically, the diameter of microspheres may range from 10 to 100 μm. Preferably, the diameter of microspheres may range from 20 to 90 μm, and more preferably, it may range from 30 to 70 μm, but is not limited to these ranges.

[0023] The skin rejuvenation composition of the present invention may be used for preventing, treating or improving skin wrinkles, elasticity, depressions, defects or facial asymmetry.

[0024] In one experimental embodiment of the present invention, it has been observed that the administration of skin rejuvenation compositions (Meso 1, Meso 2) comprising poloxamer-coated poly-D,L-lactic acid microspheres and low molecular weight hyaluronic acid leads to an increase in fibroblast density, collagen regeneration, and elastic fiber enhancement. Therefore, the composition of the present invention can be injected to fill sagging skin, defects, or depressed areas, compensate for wrinkles or lack of elasticity, and improve asymmetry by balancing the left and right sides.

[0025] The other aspect of the present invention relates to a preparation method for a skin rejuvenation composition, comprising: a) forming poly-D,L-lactic acid (PDLLA) microspheres; b) coating the microsphere with poloxamer; and c) mixing the coated microspheres from step b) with low molecular weight hyaluronic acid.

[0026] Specifically, the poly-D,L-lactic acid (PDLLA) microspheres may be contained in an amount ranging from about 0.005 %(w / v) to 0.05 %(w / v) based on the total weight of the composition, but is not limited to. Preferably, it may be contained in an amount ranging from about 0.007% (w / v) to 0.05% (w / v) based on the total weight of the composition, and more preferably, it may be contained in an amount ranging from about 0.01% (w / v) to 0.05% (w / v), but is not limited to.

[0027] Specifically, the poly-D,L-lactic acid (PDLLA) microspheres and poloxamer can be mixed at a weight ratio of 1:5 to 15, but is not limited to Preferably, they can be mixed at a weight ratio of 1:7 to 12, and more preferably, at a weight ratio of 1:9 to 11, but is not limited to.

[0028] Specifically, the molecular weight of the low molecular weight hyaluronic acid may range from 0.1 to 20 kDa. Preferably, the molecular weight of the low molecular weight hyaluronic acid may range from 0.5 to 10 kDa, and more preferably, it may range from 0.5 to 5 kDa, but is not limited to these ranges.

[0029] Specifically, the low molecular weight hyaluronic acid may be contained in an amount ranging from about 0.5 to 10 %(w / v) based on the total weight of the composition, but is not limited. Preferably, it may be contained in an amount ranging from about 0.5 to 7 %(w / v) based on the total weight of the composition, and more preferably, it may be contained in an amount ranging from about 1 to 5 %(w / v), but is not limited to.

[0030] Another aspect of the present invention relates to a method for improving skin wrinkles, elasticity, depressions, defects, or facial asymmetry, comprising the step of administering the skin rejuvenation composition. Specifically, the improvement method may be aesthetic improving method.

[0031] The improving method may involve administering the skin rejuvenation composition to the skin through injection, but is not limited to. Preferably, the injection may be administered subcutaneously or intramuscularly, and more preferably, it may be administered to the epidermis or dermis layer of the skin, but is not limited to. As needed, it can be administered through appropriate routes.

[0032] Another aspect of the present invention relates to the use of a skin rejuvenation composition in a method of preventing, treating or improving skin wrinkles, elasticity, depressions, defects or facial asymmetry, the composition comprising poly-D,L-lactic acid (PDLLA) microspheres coated with poloxamer and low molecular weight hyaluronic acid.

[0033] The skin rejuvenation composition of the present invention exhibits excellent skin rejuvenation and improvement effects by increasing the density of fibroblasts, collagen regeneration, and the quantity of elastic fibers, all while not inducing immune reactions, thus ensuring high biocompatibility.

[0034] Figure 1 shows the surface morphology of the poly-D,L-lactic acid (PDLLA) microspheres according to the presence or absence of poloxamer coating (a: PDLLA microsphere b: PDLLA microsphere with poloxamer coating).

[0035] Figure 2 shows the results of absorbance and injectability measurements according to the presence or absence of poloxamer coating ((A) UV-vis spectrum, (B) injectability test results of Meso 1 and Meso 2).

[0036] Figure 3 shows the injection sites on the mouse.

[0037] Figure 4 shows the evaluation of biocompatibility of Meso 1 and Meso 2 observed through CD68 immunohistochemical staining.

[0038] Figure 5 shows the distribution of microspheres in the epidermis after the injection of Meso 1 and Meso 2 observed through H&E staining.

[0039] Figure 6 shows the results of fibroblast density, collagen regeneration, and epidermal thickness following injections of Meso 1 and Meso 2 under different conditions ((A) observation period after one injection; (B) injection frequency; (C) injection frequency within the same period).

[0040] Figure 7 shows the distribution of collagen and epidermal thickness following injections of Meso 1 and Meso 2 under different conditions, observed through MT staining.

[0041] Figure 8 shows the observation of elastic fibers following injections of Meso 1 and Meso 2 under different conditions, as visualized through VVG staining.

[0042] Hereinafter, the present invention will be described by means of the examples. However, the following examples only exemplify the present invention, and are not intended to limit the present invention.

[0043] Manufacturing example 1. Preparation of PDLLA microspheres Coated with Pluronic F127

[0044] The preparation of PDLLA (poly-D,L-lactic acid) coated with Pluronic F127 is comprised of two steps. PDLLA (poly-D,L-lactic acid) microspheres, obtained from Regen Biotech (AestheFill; Seoul, Korea), were used as a substance approved in Korea for facial cosmetics.

[0045] Step 1:

[0046] PDLLA (poly-D,L-lactic acid) microspheres possess hydrophobic properties, which can lead to particle aggregation during injection, causing the phenomenon known as "lead block needles." To mitigate this issue, a thin layer of Pluronic was coated onto the microspheres. "Lead block needles" refer to the situation where the injection needle becomes clogged or partially obstructed, making it difficult to smoothly inject the liquid.

[0047] Specifically, to prepare a 1% (w / v) PF127 (Pluronic F127) solution, 500 mg of PF127 powder was dissolved in 50 ml of deionized water using a mechanical stirrer, and the mixture was stirred at 500 rpm at room temperature for 1 hour until homogeneous.

[0048] 50 mg of PDLLA microspheres were added to the PF127 solution (PDLLA microspheres: PF127 = 1:10 (weight ratio)). The mixture was stirred at 500 rpm at room temperature for 3 hours, and absorption filtration was conducted using Round Quantitative Filter Paper No. 5C until the PDLLA / F127 mixture powder was dried. After obtaining the powder, it was frozen using a Kingmech machine for 1-2 days.

[0049] The coated microspheres obtained through the above process were named PDLLA@F127-1.

[0050] Step 2: Preparation of the final formulation of dispersed PDLLA@F127-1 in HA solution

[0051] Initially, a 2% (w / v) hyaluronic acid (HA, low molecular weight: 2kD) solution was prepared by dissolving 0.2 g of hyaluronic acid in 10 ml of deionized water. Subsequently, two different formulations were prepared using different concentrations of PDLLA@F127-1. Specifically, 1 mg and 3 mg of PDLLA@F127-1 were each mixed with 10 ml of 2% (w / v) HA solution in two separate vials for 1-2 minutes to disperse them. The resulting product solutions were sterilized with ethylene oxide (EtO) sterilization before injection.

[0052] Manufacturing Example 2. Preparation of Example formulation 1 (Meso 1) and Example formulation 2 (Meso 2)

[0053] Different formulations of skin rejuvenation compositions were prepared.

[0054] Example 1 (Meso 1): 0.01 %(w / v) PDLLA@F127-1 + 2 %(w / v) HA

[0055] Example 2 (Meso 2): 0.03 %(w / v) PDLLA @F127-1 + 2 %(w / v) HA (total volume 10 ml)

[0056] Specifically, to prepare a 1% (w / v) PF127 (Pluronic F127) solution, 500 mg of PF127 powder was dissolved in deionized water using a mechanical stirrer, and the mixture was stirred at room temperature for 1 hour until homogeneous. Then, 50 mg of PDLLA microspheres were added to the PF127 solution (PDLLA microspheres: PF127 = 1:10 (weight ratio)), and the mixture was stirred at 500 rpm at room temperature for 3 hours. Absorption filtration using Round Quantitative Filter Paper No. 5C was conducted until PDLLA@F127-1 powder was dried. The obtained powder was collected and freeze-dried using a Kingmech machine for 1-2 days. The coated microspheres were named PDLLA@F127-1.

[0057] Subsequently, 0.2 g of hyaluronic acid (low molecular weight: 2kD) was dissolved in 10 ml of deionized water to prepare a 2 %(w / v) HA solution. Then, two formulations, namely Example 1 and Example 2, were prepared by mixing two different concentrations of PDLLA@F127-1, i.e., 1 mg and 3 mg of PDLLA@F127-1, respectively, with 10 ml of 2 %(w / v) HA solution in two separate vials for 1-2 minutes.

[0058] Experimental example 1. Characterization of Example 1 (Meso 1) and Example 2 (Meso 2)

[0059] 1-1. The surface morphology of PDLLA and PDLLA@F127-1 microspheres

[0060] The PDLLA and PDLLA@F127-1 microspheres were freeze dried for 1-2 days. Samples were directly analyzed using scanning electron microscopy (SEM) in powder form.

[0061] As shown in Figure 1, following modification with poloxamer, the surface morphology of the poly-D,L-lactic acid (PDLLA) microspheres undergoes a transformative shift, characterized by a notable transition from an irregular or rough texture to a uniformly smooth surface topography.

[0062] 1-2. The dispersion of PDLLA and PDLLA@F127-1 microspheres

[0063] The dispersion characteristics of PDLLA and PDLLA@F127-1 microspheres in HA solutions (0.01 %(w / v), 0.03 %(w / v)) were evaluated using a Jasco V-730 UV-Vis spectrophotometer. The assessment was conducted based on Liquid Mode Laser Diffractometry (LMLD), which evaluates the dispersion quality of suspensions independently by assessing how light scatters in space due to the size of floating particles in the liquid.

[0064] In addition, the injectability test was performed according to the following procedure: Firstly, 10 μl of Example 1 and Example 2 were placed in a hemocytometer, and the initial count of microspheres was determined by optical microscopy, repeated four times.

[0065] Subsequently, using a 1 ml syringe and a 30 G needle, 10 μl of Example 1 and Example 2 were loaded into the hemocytometer and counted four times using the same method. The injectability was then calculated using the following formula.

[0066]

[0067] By coating hydrophobic PDLLA with amphiphilic F127, the performance of PDLLA as a mesotherapy agent can be enhanced.

[0068] Specifically, when the absorbance of PDLLA, both coated and uncoated with different concentrations of F127, was examined, it was observed that the dispersion of uncoated 0.01 %(w / v) and 0.03 %(w / v) PDLLA was poor, resulting in minimal absorbance, as shown in Figure 2(a). However, in the case of Meso 1 and Meso 2, the absorbance was significantly higher, indicating that the dispersion ability of PDLLA was greatly improved by coating with F127.

[0069] Furthermore, as shown in Figure 2(b), uncoated 0.01 %(w / v) and 0.03 % (w / v) PDLLA exhibited poor dispersion, resulting in low injectability of 75 % and 72%, respectively. In contrast, Meso 1 and Meso 2 demonstrated effective dispersion, showing high injectability of 96 % and 94 %, respectively, through the injection needle. While precipitation of microspheres may occur in the absence of F127 coating, the presence of F127 in Meso 1 and Meso 2 mitigated the impact of increasing PDLLA concentration on injectability, indicating potential for administration at higher concentrations.

[0070] These results indicate that the coating of PDLLA microspheres with F127 significantly enhances dispersion and injectability, thereby preventing microsphere aggregation and increasing the efficacy of mesotherapy after injection.

[0071] Experiment Example 2.In vivoAnimal Study

[0072] Male BALB / c mice aged 8 weeks were purchased from BioLASCO (Taiwan Co., Ltd). A total of 25 mice were isolated and acclimatized for one week with access to food and water ad libitum. Subsequently, they were randomly divided into four groups (Table 1).

[0073] [Table 1]

[0074]

[0075] Phosphate-buffered saline (PBS) was injected into the left thigh skin of mice as the control group, while Example 1 (Meso 1) and Example 2 (Meso 2) were injected into the right thigh. The injection sites are illustrated in Figure 3.

[0076] Specifically, after administering 0.15 ml of anesthesia (Zoletil 50) at a concentration of 10 mg / ml via intramuscular injection, the area was shaved. Subsequently, Meso 1, Meso 2, and PBS were each injected subcutaneously into the lateral side of the mouse at a volume of 200 μl. After the observation period, the mice were sacrificed, and tissues were collected, fixed in 4 % paraformaldehyde solution, and sliced into consecutive sections.

[0077] After staining with Hematoxylin-eosin (H&E), Verhoeff-Van Gieson (VVG), or Masson's trichrome (MT), the samples were analyzed using ImageJ image analysis software.

[0078] Macrophages were identified using CD 68 Immunohistochemical staining, the histological structure and collagen fibers of tissue sections were analyzed using H&E and MT staining. Elastic fibers were identified using VVG staining.

[0079] CD68 immunohistochemical staining was used to evaluate the immunological effect of PDLLA coated with F127. Mice were administered PBS (control group), Meso 1, and Meso 2 once, and sacrificed one week later for observation. As a result, it was confirmed that there was no significant difference in the amount of macrophages between the control group, Meso 1 and Meso 2 injection groups, as shown in Figure 4. As shown in Figure 4, the result suggests that Meso 2 has found more CD 68+ signals than Meso 1. In fact, Inflammation around an implant particle is normal. When the body detects a foreign substance, such as a dermal filler, it initiates an inflammatory response. This inflammatory process can activate fibroblasts, cells producing collagen and elastin. As a result, the surrounding tissue may undergo remodeling, leading to increased collagen and elastin synthesis.

[0080] In addition, PBS (control), Meso 1, and Meso 2 were administered according to Table 1, followed by H&E staining and observation. After 1 week, a large amount of Meso 1 and Meso 2 microspheres were distributed in the epidermal layer (Fig. 5(A1) to (A3)). Furthermore, these Meso 1 and Meso 2 microspheres were rarely observed after 2-week period following injection (Fig. 5(B1) to (B3)), indicating the absorption of Meso 1 and Meso 2 microspheres and induction of collagen regeneration.

[0081] In the control group, the connective tissue appeared loosely organized, whereas in the groups injected with Meso 1 and Meso 2, a higher and more uniform cell density was observed. Particularly, there was a significant increase in the number of fibroblasts in the skin compared to the control group.

[0082] As shown in Figure 6, it was observed that Meso 2, containing a higher concentration of PDLLA compared to Meso 1, promoted tissue formation with a greater number of fibroblasts.

[0083] In addition, with an increase in the number of injections or a longer period between the first injection and observation, the regeneration rate of fibroblasts increased. It was observed that there was about 19 % increase in fibroblast regeneration at the 2-week observation compared to the 1-week observation post the first injection (Figure 6(A)). Both Meso 1 and Meso 2 showed an increase of 20 % and 23 %, respectively, in fibroblast regeneration after three injections compared to one injection (Figure 6(B)).

[0084] In addition, when Meso 1 and Meso 2 were injected at different frequencies, it was observed that three injections had superior effects compared to two injections (Figure 6(C)). Considering these results together, i) the concentration of PDLLA, ii) the number of injections, and iii) the injection frequency influence the density of fibroblasts. It can be concluded that as the concentration of PDLLA increases, the number of injections increases, and the injection frequency increases, the density of fibroblasts increases.

[0085] In addition, both Meso 1 and Meso 2 exhibited greater amounts of collagen and thicker epidermis compared to the control group. Specifically, there was a significant increase in collagen regeneration in both Meso 1 and Meso 2 compared to the control group (Figures 6(G)-(I)), and epidermal thickness was also significantly increased in both Meso 1 and Meso 2 compared to the control group (Figures 6(J)-(L)).

[0086] In addition, both Meso 1 and Meso 2 exhibited increases in collagen regeneration of 6.8% and 10.2%, respectively, when comparing three injections to one injection (Figure 6(H)), and the epidermal thickness increased by 11.0 μm and 26.4 μm, respectively.

[0087] Furthermore, when Meso 1 and Meso 2 were injected at different frequencies, three injections resulted in a 0.8% increase in collagen regeneration for Meso 2 compared to two injections (Figure 6(I)), and epidermal thickness increased by 5.6 μm for Meso 1 and 19.2 μm for Meso 2.

[0088] Fibroblasts play a crucial role in collagen regeneration, and collagen stimulation is associated with epidermal thickness. Collagen distribution and epidermal thickness were observed using Masson's trichrome staining after injection of the composition of the present invention. Since collagen appears blue, a higher proportion of blue indicates more collagen regeneration. Observation of Masson's trichrome staining revealed that in the groups injected with Meso 1 and Meso 2, the collagen areas appeared mostly blue, indicating an increase in epidermal thickness (Figure 7).

[0089] The results regarding collagen regeneration are consistent with fibroblast density and indicate an increase in collagen production by fibroblasts. Along with higher collagen formation, there was an increase in epidermal thickness. These findings suggest that the composition of the present invention can enhance skin moisture and elasticity by increasing the density of skin collagen fibers generated by activated fibroblasts for skin rejuvenation purposes, thereby promoting skin improvement.

[0090] Elastic fibers are connective tissue fibers that allow tissue to stretch, are abundant in the aorta, and provide flexibility to blood vessels. After the injection of the control group, Meso 1, and Meso 2, elastic fibers were observed through VVG staining, indicating that higher injection frequencies were associated with higher concentrations of elastic fibers (Figure 8).

[0091] The composition of the present invention exhibits excellent skin rejuvenation and improvement effects by increasing the density of fibroblasts, promoting collagen regeneration, and enhancing the amount of elastic fibers. Furthermore, it does not induce immune reactions and maintains high biocompatibility.

[0092] The foregoing description of the present invention has been presented for illustrative purposes, and it is apparent to a person having ordinary skill in the art that the present invention can be easily modified into other detailed forms without changing the technical idea or essential features of the present invention. Therefore, it should be understood that the forgoing embodiments are by way of example only, and are not intended to limit the present disclosure. For example, each component which has been described as a unitary part can be implemented as distributed parts. Likewise, each component which has been described as distributed parts can also be implemented as a combined part.

[0093] The scope of the present invention is presented by the accompanying claims, and it should be understood that all changes or modifications derived from the definitions and scopes of the claims and their equivalents fall within the scope of the present invention.

Claims

1.A skin rejuvenation composition comprising poly-D,L-lactic acid (PDLLA) microspheres coated with poloxamer; and low molecular weight hyaluronic acid.2.The skin rejuvenation composition of claim 1, wherein the poloxamer is selected from the group consisting of poloxamer 101, 105, 108, 122, 123, 124, 181, 182, 183, 184, 185, 188, 212, 215, 217, 231, 234, 235, 237, 238, 282, 284, 288, 331, 333, 334, 335, 338, 401, 402, 403 and 407.3.The skin rejuvenation composition of claim 1, wherein the poly-D,L-lactic acid (PDLLA) microspheres are hydrophobic.4.The skin rejuvenation composition of claim 1, wherein the poly-D,L-lactic acid (PDLLA) microspheres are contained in an amount ranging from about 0.005 %(w / v) to 0.05 %(w / v) based on the total weight of the composition.5.The skin rejuvenation composition of claim 1, wherein the poly-D,L-lactic acid (PDLLA) microspheres and poloxamers are mixed in a weight ratio of about 1:5 to 15.6.The skin rejuvenation composition of claim 1, wherein the molecular weight of the low molecular weight hyaluronic acid is about 0.1 to 20 kDa.7.The skin rejuvenation composition of claim 1, wherein the low molecular weight hyaluronic acid is contained in amount ranging from about 0.5 %(w / v) to 10 %(w / v) based on the total weight of the composition.8.The skin rejuvenation composition of claim 1, wherein the diameter of microspheres is 10 to 100 μm.9.The skin rejuvenation composition of claim 1, wherein the composition exhibits enhanced stability and prolonged retention.10.The skin rejuvenation composition of claim 1, wherein the composition is administered by injection.11.The skin rejuvenation composition of claim 1, wherein the composition is for preventing, treating or improving skin wrinkles, elasticity, depressions, defects or facial asymmetry.12.A preparation method for a skin rejuvenation composition, comprising:a) forming poly-D,L-lactic acid (PDLLA) microspheres;b) coating the microsphere with poloxamer; andc) mixing the coated microspheres from step b) with low molecular weight hyaluronic acid.13.The preparation method of claim 12, wherein the poloxamer is selected from the group consisting of poloxamer 101, 105, 108, 122, 123, 124, 181, 182, 183, 184, 185, 188, 212, 215, 217, 231, 234, 235, 237, 238, 282, 284, 288, 331, 333, 334, 335, 338, 401, 402, 403 and 407.14.The preparation method of claim 12, wherein the poly-D,L-lactic acid (PDLLA) microspheres are hydrophobic.15.The preparation method of claim 10, wherein the poly-D,L-lactic acid (PDLLA) microspheres are contained in an amount ranging from about 0.005 %(w / v) to 0.05 %(w / v) based on the total weight of the composition.16.The preparation method of claim 10, wherein the poly-D,L-lactic acid (PDLLA) microspheres and poloxamers are mixed in a weight ratio of about 1:5 to 15.17.The preparation method of claim 10, wherein the molecular weight of the low molecular weight hyaluronic acid is about 0.1 to 20 kDa.18.The preparation method of claim 10, wherein the low molecular weight hyaluronic acid is contained in amount ranging from about 0.5 %(w / v) to 10 %(w / v) based on the total weight of the composition.19.The preparation method of claim 10, wherein the composition exhibits enhanced stability and prolonged retention.20.A method of for improving skin wrinkles, elasticity, depressions, defects, or facial asymmetry, comprising the step of administering the composition of claim 1 to the skin.21.The method of claim 16, wherein the method is the aesthetic improving method.22.The method of claim 15, wherein the composition is administered by injection.23.The use of a skin rejuvenation composition in a method of preventing, treating or improving skin wrinkles, elasticity, depressions, defects or facial asymmetry, the composition comprising poly-D,L-lactic acid (PDLLA) microspheres coated with poloxamer and low molecular weight hyaluronic acid.

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