Injectable stem cell-loaded microsphere hydrogel fiber, preparation method and application thereof

Abstract

The application belongs to the technical field of biological medicine, and discloses an injectable stem cell microsphere hydrogel fiber, a preparation method and application. The injectable stem cell microsphere hydrogel fiber comprises a hydrogel fiber support and stem cell microspheres distributed and planted in the pores of the hydrogel fiber support. The hydrogel fiber support is formed by disordered stacking of degradable polyester fibers with an orientation structure, and each degradable polyester fiber is solidified with a super-hydrophilic hydrogel coating. The hydrogel fiber support has a three-dimensional porous structure. The injectable stem cell microsphere hydrogel fiber can achieve the purpose of treating osteoarthritis and joint cartilage injury through minimally invasive injection, and can improve the survival rate of stem cells after injection and promote the chondrogenic differentiation of stem cells. Compared with the treatment method of injecting discrete stem cells, the injectable stem cell microsphere hydrogel fiber has stronger cell planting capacity, higher cell survival rate and more excellent chondrogenic differentiation efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biological medicine, and particularly relates to an injectable stem cell-loaded microsphere hydrogel fiber as well as a preparation method and application thereof. BACKGROUND

[0002] Stem cells are cells that have the ability of self-renewal and differentiation, and they have the potential to differentiate into multiple different types of cells, including bone cells, cartilage cells and synovial membrane cells. In recent years, stem cell therapy has attracted widespread attention as a new method for treating osteoarthritis. Although stem cell therapy can improve the symptoms of osteoarthritis patients in the short term, some studies have shown that its long-term efficacy is still uncertain. This is because direct injection of discrete-state stem cells into osteoarthritis and articular cartilage defects can easily lead to stem cell loss, resulting in reduced efficacy. In order to solve this problem, researchers have tried to combine stem cells with hydrogels to form stem cell-loaded hydrogels, and inject them into the affected area for treatment by minimally invasive injection. However, the discrete-state stem cells in such stem cell-loaded hydrogels are more susceptible to the complex microenvironment of the affected area, resulting in a lower survival rate.

[0003] Therefore, there is an urgent need to provide a stem cell drug that is less affected by the complex microenvironment and has stable efficacy, which can be injected by minimally invasive injection to achieve the purpose of treating osteoarthritis and articular cartilage damage. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides an injectable stem cell-loaded microsphere hydrogel fiber as well as a preparation method and application thereof. The injectable stem cell-loaded microsphere hydrogel fiber provided by the present application is less affected by the complex microenvironment of the affected area, has safe and stable efficacy, and can achieve the purpose of treating osteoarthritis and articular cartilage damage by minimally invasive injection.

[0005] The present application provides a hydrogel fiber scaffold.

[0006] Specifically, a hydrogel fiber scaffold is formed by disordered stacking of degradable polyester fibers with an oriented structure, and each of the degradable polyester fibers is solidified with a super-hydrophilic hydrogel coating. The hydrogel fiber scaffold has a three-dimensional porous structure.

[0007] It should be noted that the degradable polyester fibers are not physically / chemically cross-linked and bonded, and the surface of each degradable polyester fiber is solidified with a super-hydrophilic hydrogel coating.

[0008] Preferably, the degradable polyester fibers are non-shortened degradable polyester fibers.

[0009] Preferably, the length of the non-short-cut degradable polyester fiber is greater than 1 mm; further preferably, the length of the non-short-cut degradable polyester fiber is greater than 3 mm, such as greater than 3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, 15 mm, 20 mm, etc. Compared with short-cut fiber bundles (length less than 1 mm, even less than 0.1 mm), long fibers are more likely to form a three-dimensional porous fiber scaffold by stacking, and are less likely to disperse and be lost with body fluid after being implanted into a lesion, which is beneficial to the colonization of stem cells.

[0010] Preferably, the degradable polyester fiber comprises at least one of lactic acid-glycolic acid copolymer (PLGA), polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), poly(lactic acid-trimethylene carbonate), polycaprolactone (PCL), polylactic acid-polyethylene glycol block copolymer, polycaprolactone-polyethylene glycol block copolymer, hydroxybutyric acid and hydroxyvaleric acid copolymer.

[0011] Preferably, the super-hydrophilic hydrogel coating is formed by curing a super-hydrophilic hydrogel, and the super-hydrophilic hydrogel comprises at least one of methacrylamidated hyaluronic acid (HA-MA), methacrylamidated polyethylene glycol (PEGDA), and methacrylamidated sodium alginate. The hydrogel layer formed after curing of the super-hydrophilic hydrogel has super-hydrophilicity, and when discrete stem cells are seeded, the cells cannot adhere to the fiber surface in the scaffold and cannot grow and elongate along the fibers, but spontaneously aggregate between cells (cells can only adhere to each other if they cannot adhere to the material), which can quickly form cell aggregates or cell microspheres. The preferred super-hydrophilic hydrogel is a hydrogel molecule that has biocompatibility, a small water contact angle, and weak adhesion to cells after curing.

[0012] Preferably, in the three-dimensional porous structure of the hydrogel fiber scaffold, a plurality of pores are contained, and the size of the pores is 10 μm-1000 μm; further preferably, the size of the pores is 50 μm-500 μm. By controlling the size of the pores, it is beneficial for cells to aggregate in the pores, and if the pores are too small, it is not conducive for cells to enter, and if the pores are too large, it is easy to cause the escape of cells, which is not conducive to the formation of cell aggregates.

[0013] The application also provides a preparation method of a hydrogel fiber scaffold.

[0014] Specifically, a preparation method of a hydrogel fiber scaffold comprises the following steps:

[0015] (1) a degradable polyester solution or a high-temperature molten degradable polyester melt is prepared by electrospinning technology to obtain degradable polyester fibers with an oriented structure, the degradable polyester fibers are not in contact with each other, the diameter of the fiber filaments is 100 nanometers to 100 micrometers, and the spacing between the fiber filaments is not less than 50 micrometers;

[0016] (2) an ultrahydrophilic hydrogel solution is prepared, a photoinitiator is added, and then the degradable polyester fibers prepared in step (1) are immersed in the ultrahydrophilic hydrogel solution, so that each fiber filament of the degradable polyester fibers with an oriented structure is coated with the ultrahydrophilic hydrogel solution; and then the ultrahydrophilic hydrogel solution is cured by light irradiation to obtain hydrogel fibers with an oriented structure and a core-shell structure;

[0017] (3) water is added to the hydrogel fibers prepared in step (2) and stirred, so that the hydrogel fibers are stacked in a cotton-like three-dimensional structure in water, and then dried to obtain hydrogel fiber scaffolds with a three-dimensional porous structure.

[0018] Preferably, the degradable polyester solution in step (1) comprises a degradable polyester and a solvent, and the solvent comprises at least one of dichloromethane and hexafluoroisopropanol.

[0019] Preferably, the mass concentration of the degradable polyester solution is 5% to 30%, such as 20%.

[0020] Preferably, the degradable polyester fibers in step (1) are non-short-cut degradable polyester fibers.

[0021] Preferably, the length of the non-short-cut degradable polyester fibers is greater than 1 mm; further preferably, the length of the non-short-cut degradable polyester fibers is greater than 3 mm, such as greater than 3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, 15 mm, 20 mm, etc.

[0022] Preferably, the diameter of the fiber filaments is 1 to 30 micrometers; further preferably, the diameter of the fiber filaments is 5 to 15 micrometers.

[0023] Preferably, the electrospinning technology in step (1) is near-field direct writing or far-field electrospinning technology.

[0024] In step (1), the distance between the parallel fibers is controlled to be not less than 50 micrometers, which can avoid the fibers close to each other from spontaneously adhering to a bundle when the ultrahydrophilic hydrogel solution is immersed in step (2), so that the hydrogel fibers with an oriented structure and a single distribution cannot be prepared after curing.

[0025] Preferably, the spacing between the fiber filaments is 50 to 200 micrometers.

[0026] Preferably, the super-hydrophilic hydrogel in step (2) comprises at least one of methacrylamidated hyaluronic acid (HA-MA), methacrylamidated polyethylene glycol (PEGDA), and methacrylamidated sodium alginate. For example, methacrylamidated hyaluronic acid, methacrylamidated polyethylene glycol, or high molecular weight methacrylamidated sodium alginate with a molecular weight of 500 to 2 million.

[0027] Preferably, the mass concentration of the super-hydrophilic hydrogel solution in step (2) is 0.1% to 10%.

[0028] Preferably, the photoinitiator in step (2) is a special requirement, such as Irgacure 2959 and LAP initiator.

[0029] Preferably, the mass concentration of the photoinitiator in step (2) is 0.01% to 0.5%.

[0030] Preferably, the process of light curing in step (2) is to irradiate the surface of the degradable polyester fiber with ultraviolet light or blue light to cure the super-hydrophilic hydrogel.

[0031] It can be understood that after the preparation in step (2) is completed, the hydrogel fiber with oriented structure and core-shell structure can be sheared and then used. The reason why steps (1) and (2) are prepared into oriented fibers is to make it easier to apply a hydrogel coating to the surface of each fiber and to make the fibers not stick to each other after curing.

[0032] Preferably, the drying in step (3) is freeze-drying.

[0033] The present application also provides an injectable stem cell microsphere-loaded hydrogel fiber.

[0034] Specifically, the injectable stem cell microsphere-loaded hydrogel fiber comprises the above-mentioned hydrogel fiber scaffold and stem cell microspheres distributed and planted in the pores of the hydrogel fiber scaffold.

[0035] The present application also provides a preparation method of an injectable stem cell microsphere-loaded hydrogel fiber.

[0036] Specifically, the preparation method of the injectable stem cell microsphere-loaded hydrogel fiber comprises the following steps:

[0037] The discrete stem cells are planted in the above-mentioned hydrogel fiber scaffold, and the stem cells spontaneously aggregate to form stem cell microspheres (aggregates), thereby obtaining the injectable stem cell microsphere-loaded hydrogel fiber.

[0038] Due to the super-hydrophilic layer on the degradable polyester fiber in the hydrogel fiber scaffold, the surface of the hydrogel fiber scaffold is not cell-adhesive, so that the stem cells seeded into the hydrogel fiber scaffold can spontaneously aggregate in the pores of the scaffold within a short time (12 hours) and adhere to each other by secreting extracellular matrix, thereby forming a large number of stem cell aggregates (microspheres). These stem cell aggregates are distributed and colonized in the pores of the hydrogel fiber scaffold.

[0039] Preferably, the stem cells further comprise a step of sterilizing the hydrogel fiber scaffold before being seeded into the hydrogel fiber scaffold. The sterilization can be performed by gamma ray irradiation.

[0040] Preferably, the stem cells are any generation from primary to P10. The stem cells can be mesenchymal stem cells derived from umbilical cord, bone marrow or fat.

[0041] The application also provides the use of the above-mentioned injectable stem cell microsphere-loaded hydrogel fiber.

[0042] Specifically, the above-mentioned injectable stem cell microsphere-loaded hydrogel fiber is used in the preparation of a drug for treating osteoarthritis or a drug for treating articular cartilage injury. The above-mentioned injectable stem cell microsphere-loaded hydrogel fiber is used to prepare a drug for treating osteoarthritis or a drug for treating articular cartilage injury, which is injected through a 27G needle for minimally invasive injection, and can maintain a high survival rate of cell microspheres after injection, thereby achieving the purpose of treating osteoarthritis and articular cartilage injury.

[0043] As a specific application method, the above-mentioned injectable stem cell microsphere-loaded hydrogel fiber can be mixed with a lubricant and then injected into the patient's osteoarticular or cartilage defect site, so as to fix the injectable stem cell microsphere-loaded hydrogel fiber at the affected site and achieve the therapeutic effect. The lubricant mainly plays a lubricating role to facilitate injection and has no special requirements. Unmodified hyaluronic acid (HA) or type I collagen hydrogel or gelatin solution can be used.

[0044] Compared with the prior art, the application has the following advantages:

[0045] (1) The present application is to dip super-hydrophilic hydrogel precursor on each parallel fiber surface of degradable polyester fiber with oriented structure, and to realize light curing of hydrogel coating under the condition that the fibers are not adhered to each other. The hydrogel fibers after such curing are still not adhered to each other. And the non-connected hydrogel fibers can form a three-dimensional porous structure with different pore sizes under the action of external force (stirring), and by the super-hydrophilicity of the super-hydrophilic hydrogel on the fiber surface, the cells are spontaneously aggregated by cell anti-adhesion during cell planting, and then different size stem cell microspheres are obtained. More importantly, after the stem cells form cell microspheres in the three-dimensional porous scaffold, the fibers in the scaffold can still slide relatively under the action of external force, and the relative sliding ability between the fibers can make the injectable stem cell microsphere-loaded hydrogel fiber continue to change the shape, and realize the minimally invasive injection of the cell microsphere-loaded hydrogel fiber by the "lubricating" property of sliding. During the injection process, the fibers are subjected to pressure in the needle, and are changed from a three-dimensional structure to an oriented quasi-one-dimensional structure, carrying the stem cell microspheres through the needle, and accumulating like soft noodles in the cartilage defect, realizing the filling of the defect. The injectable stem cell microsphere-loaded hydrogel fiber provided by the present application has better cell survival ability than discrete stem cells, and is less likely to undergo apoptosis due to injection pressure during minimally invasive injection. The stem cell microspheres are larger in size and more difficult to "escape" from the fiber scaffold, making it easier for stem cells to colonize the affected area. The cells inside the stem cell microspheres are more hypoxic than discrete stem cells, which is beneficial to the chondrogenic differentiation of stem cells.

[0046] (2) The injectable stem cell microsphere-loaded hydrogel fiber provided by the present application can improve the survival rate and chondrogenic differentiation ability of stem cells; and it is less affected by the complex microenvironment of the affected area, and has safe and stable efficacy, and can achieve the purpose of treating osteoarthritis and joint cartilage injury through minimally invasive injection. Compared with the strategy of treating osteoarthritis with discrete stem cells, it has stronger cell colonization ability (does not drift everywhere), higher cell survival rate, and more excellent chondrogenic differentiation efficiency, and smaller surgical trauma. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 Figure 9 is an inverted fluorescence microscope image of a single PLGA fiber before and after coating HA-MA hydrogel under a 10x objective lens;

[0048] Figure 2 Figure 10 is a body microscope 4x objective lens image of PLGA fiber, PLGA / HA-MA fiber and PLGA / HA-MA scaffold;

[0049] Figure 3 Figure 11 is an inverted fluorescence microscope image of PLGA / HA-MA scaffold and PLGA / HA-MA scaffold implanted with mesenchymal stem cells under a 10x objective lens;

[0050] Figure 4 Figure 7 is a fluorescence image of a cell death and viability staining under an inverted fluorescence microscope at 4x magnification;

[0051] Figure 5 Figure 8 is a fluorescence image of a cytoskeleton protein staining under an inverted fluorescence microscope at 10x magnification;

[0052] Figure 6 Figure 9 is a fluorescence image of a staining of a cartilage protein after a chondrogenic differentiation of a cell microsphere;

[0053] Figure 7 Figure 10 is a diagram of a simulation of a process of injecting a cell microsphere-containing fiber scaffold using a syringe. DETAILED DESCRIPTION

[0054] In order to make the skilled in the art more clearly understand the technical solutions described in the present application, the following examples are listed for illustration. It should be pointed out that the following examples do not constitute a limitation on the scope of protection required by the present application.

[0055] The raw materials, reagents or devices used in the following examples, unless otherwise specified, can be obtained from conventional commercial channels or can be obtained by existing known methods.

[0056] EXAMPLE

[0057] 1. Preparation of PLGA fibers

[0058] 3g of PLGA was dissolved in 5mL of dichloromethane (DCM), and after complete dissolution, printing was performed using a near-field direct writing electrospinning machine, with the printing parameters set as: voltage 2kV, air pressure 7kPa, needle and collection plate distance 1.2mm, single fiber diameter 15 microns, and two fiber spacing 200 microns, to obtain PLGA fibers with an oriented structure. Figure 1 Figure 1 is an inverted fluorescence microscope image of a single PLGA fiber, Figure 2 Figure 2 is a microscope ocular image of a single PLGA fiber.

[0059] 2. Preparation of PLGA / HA-MA hydrogel fibers

[0060] The printed fibers were collected and a methyl methacrylamide hyaluronic acid (HA-MA) aqueous solution with a concentration of 3% and a molecular weight of 5 million was prepared, and a photoinitiator LAP with a concentration of 0.25% was added to the aqueous solution; the PLGA fibers with an oriented structure were immersed in the HA-MA aqueous solution and then taken out, so that each fiber surface was coated with the HA-MA aqueous solution, and the excess solution was removed, to obtain PLGA / HA-MA hydrogel fibers with an oriented structure, and the fiber filaments of the PLGA / HA-MA hydrogel fibers were not adhered to each other.

[0061] The PLGA / HA-MA hydrogel fiber with orientation is irradiated by ultraviolet light (wavelength 365 nm) to solidify the HA-MA hydrogel on the surface of the PLGA fiber, forming a PLGA / HA-MA hydrogel fiber with core-shell structure. Figure 1 Fig. b is an inverted fluorescence microscope image of the PLGA / HA-MA hydrogel fiber after photocuring after coating with HA-MA hydrogel. The obviously transparent and swollen part in the figure is the hydrogel after solidification. Figure 2 Fig. b is a microscope ocular image of the PLGA / HA-MA hydrogel fiber Figure 1 Fig. a and b both have a scale of 10 μm; Figure 2 Fig. a and b both have a scale of 20 μm.

[0062] 3. Preparation of PLGA / HA-MA hydrogel fiber scaffold

[0063] 0.1 g of dry single PLGA / HA-MA hydrogel fiber with orientation is collected and added to a 50 mL centrifuge tube with 20 mL of deionized water for magnetic stirring until the PLGA / HA-MA hydrogel fiber forms a cotton-like three-dimensional structure in water. Freeze-drying is performed to obtain a PLGA / HA-MA hydrogel fiber scaffold with three-dimensional disordered porous structure. The microscope ocular image of the PLGA / HA-MA hydrogel fiber scaffold is shown in Figure 2 Fig. c and d.

[0064] 4. Preparation of injectable stem cell-loaded microsphere hydrogel fiber using PLGA / HA-MA hydrogel fiber scaffold

[0065] The PLGA / HA-MA fiber scaffold with three-dimensional disordered porous structure is sterilized (gamma rays), and then the PLGA / HA-MA hydrogel fiber scaffold is placed in a 96-well plate (the morphological image is shown in Figure 3 Fig. a), and then 1×10 6 High-concentration P6 stem cells are seeded into the PLGA / HA-MA hydrogel fiber scaffold. Due to the superhydrophilic HA-MA hydrogel coating of the PLGA fiber in the scaffold, the scaffold surface is not cell-adhesive, so that the stem cells seeded into the scaffold spontaneously aggregate and adhere to each other through the secretion of extracellular matrix in a short time (12 hours), forming a large number of stem cell aggregates (cell microspheres). Figure 3 Fig. b is a morphological image of the PLGA / HA-MA hydrogel fiber scaffold after mesenchymal stem cell implantation. The closely arranged translucent spherical structures in the figure are the morphology of the cells just seeded into the scaffold. It can be seen from Figure 3 Fig. b that the PLGA / HA-MA hydrogel fiber scaffold has been implanted with mesenchymal stem cells Figure 3 Fig. a and b both have a scale of 200 μm.

[0066] After 12 hours of stem cell entry, the cytoskeleton protein F-actin was stained with a phalloidin staining agent, and the laser was excited to green fluorescence under an inverted fluorescence microscope. Figure 4 and Figure 5 are cell death and cell viability fluorescence staining images under an inverted fluorescence microscope four times and ten times objective lens, respectively. Among them Figure 4 a, b, c, and d in the figure represent the fluorescence images of different areas (the scale is 200 μm), and the bright field image and the green fluorescence image are superimposed. The cell microspheres are circled by a blue dashed line, and the cells show green fluorescence, indicating that the cells are alive. Figure 5 a, c, and e in the figure are bright field and fluorescence superimposed images, Figure 5 b, d, and f in the figure are fluorescence images corresponding to a, c, and e at the same position (the scale is 200 μm). By Figure 4 , 5 It can be observed that most of the cells have formed cell aggregates (cell microspheres), specifically Figure 4 , 5 the circled part in the figure. By Figure 4 It can also be seen that the PLGA / HA-MA hydrogel fiber scaffold has a three-dimensional porous structure, containing multiple pores, and the size of the pores is 50-200 μm.

[0067] After the stem cells aggregated, they were cultured with chondrogenic differentiation solution for 21 days. Then they were fixed with paraformaldehyde, washed twice with PBS (phosphate buffer) after one hour, and then stained with three kinds of chondrocyte protein staining agents, collagen II staining agent, sox9 staining agent, and ACAN staining agent. Figure 6 are fluorescence images of chondrocyte protein staining after chondrogenic differentiation of cell microspheres, in which Figure 6 a is a fluorescence image of collagen II staining agent staining chondrocyte protein, Figure 6 b is a fluorescence image of Sox9 staining agent staining chondrocyte protein, Figure 6 c is a fluorescence image of ACAN staining agent staining chondrocyte protein (the scale is 200 μm). By Figure 6 It can be seen that the stem cell microspheres express bright red fluorescence, corresponding to high expression of collagen II, sox9, and aggrecan (ACAN) chondrogenic differentiation protein markers, respectively, indicating that the chondrogenic differentiation efficiency of stem cells in the stem cell microspheres is very high.

[0068] 5. Using a syringe to simulate the injection process of the injectable stem cell microsphere-loaded hydrogel fiber

[0069] The hyaluronic acid (HA) with a mass fraction of 2% and a molecular weight of 100,000 is prepared, and the injectable stem cell microsphere hydrogel fiber is mixed with the HA solution and placed in a syringe. The piston is pushed to extrude the injectable stem cell microsphere hydrogel fiber through the needle hole, and the extruded fiber is accumulated like noodles at the affected area for repairing cartilage defects. The process is shown in Figure 7 The injectable stem cell microsphere hydrogel fiber is shown in the dashed circle in Figure 7 The fiber bundle in Figure 7 It can be seen from the fiber bundle in

[0070] The present application prepares an injectable hydrogel fiber scaffold that enables mesenchymal stem cells (such as umbilical cord, bone marrow or adipose-derived) to spontaneously form stem cell microspheres. After the stem cells are planted in the hydrogel fiber scaffold, the stem cells spontaneously form stem cell aggregates or microspheres in the interstices of the scaffold due to the cell adhesion resistance of the hydrogel, and are planted in the scaffold. This injectable stem cell microsphere hydrogel fiber can be minimally invasively injected into the joint cavity or the joint cartilage defect, and plays a role in treating osteoarthritis or joint cartilage damage, thereby replacing the existing minimally invasive injection of discrete stem cell hydrogel.

[0071] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A hydrogel fiber scaffold, characterized in that, It is formed by disordered stacking of biodegradable polyester fibers with an oriented structure, wherein no physical / chemical crosslinking or adhesion is formed between the biodegradable polyester fibers; each of the biodegradable polyester fibers is cured with a superhydrophilic hydrogel coating, and the hydrogel fiber scaffold has a three-dimensional porous structure; the biodegradable polyester fibers are non-chopped biodegradable polyester fibers; the length of the non-chopped biodegradable polyester fibers is greater than 6 mm. The method for preparing the hydrogel fiber scaffold includes the following steps: (1) The biodegradable polyester solution was printed using a near-field direct writing electrospinning machine with a needle and collection plate spacing of 1.2 mm, a single fiber diameter of 5-15 micrometers, and a spacing between two fibers of 50-200 micrometers to obtain biodegradable polyester fibers with an oriented structure. (2) Prepare a superhydrophilic hydrogel solution and add a photoinitiator. Then, impregnate the biodegradable polyester fiber prepared in step (1) with the superhydrophilic hydrogel solution so that each fiber of the biodegradable polyester fiber is coated with the superhydrophilic hydrogel solution. Then, cure by light to obtain hydrogel fiber. (3) Add water to the hydrogel fiber prepared in step (2), stir, and let the hydrogel fiber stack in the water to form a cotton-like three-dimensional structure. Then dry it to obtain a hydrogel fiber scaffold.

2. The hydrogel fiber scaffold according to claim 1, characterized in that, The biodegradable polyester fiber includes at least one of lactic acid-glycolic acid copolymer, polylactic acid, polybutylene succinate, polyhydroxy fatty acid ester, poly(lactic acid-trimethylene carbonate), polycaprolactone, polylactic acid-polyethylene glycol block copolymer, polycaprolactone-polyethylene glycol block copolymer, hydroxybutyric acid and hydroxyvalerate copolymer.

3. The hydrogel fiber scaffold according to claim 1 or 2, characterized in that, The superhydrophilic hydrogel coating is formed by curing a superhydrophilic hydrogel; the superhydrophilic hydrogel includes at least one of methacrylamide-modified hyaluronic acid, methacrylamide-modified polyethylene glycol, and methacrylamide-modified sodium alginate.

4. The hydrogel fiber scaffold according to claim 1, characterized in that, The mass concentration of the biodegradable polyester solution in step (1) is 5%-30%.

5. A stem cell-loaded microsphere hydrogel fiber, characterized in that, It includes the hydrogel fiber scaffold according to any one of claims 1-4 and stem cell microspheres distributed and colonized in the pores of the hydrogel fiber scaffold.

6. The method for preparing stem cell-loaded microsphere hydrogel fibers according to claim 5, characterized in that, Includes the following steps: Discrete stem cells are seeded into a hydrogel fiber scaffold according to any one of claims 1-4, and the stem cells spontaneously aggregate to form stem cell microspheres, thereby obtaining stem cell microsphere-loaded hydrogel fibers.

7. The use of the stem cell-loaded microsphere hydrogel fiber according to claim 5 in the preparation of drugs for treating osteoarthritis or articular cartilage damage.

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