Antibiotic-loaded nano-platelet vesicle as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of medical configuration products, and discloses an antibiotic-loaded nano-platelet vesicle as well as a preparation method and application thereof. The preparation method comprises the following steps: separating and enriching platelets from peripheral blood of veins through differential centrifugation to obtain platelets, mixing and incubating the platelets with an antibiotic drug, performing nanocrystallization through non-contact ultrasound, and performing membrane extrusion to obtain the antibiotic-loaded nanoplatelet vesicles. While cell factors related to anti-inflammation in platelets are reserved, proteins related to targeted bacteria and proteins related to immunoregulation are enriched on the surfaces of the vesicles, so that bacterial targeting, inflammation and immunoregulation functions can be efficiently realized. After the antibiotic-loaded nano platelet vesicles are mixed with fibrinogen and thrombin to prepare gel, the gel can be used as a medicine for adjusting inflammation, resisting bacteria, promoting endothelial tubulation and accelerating healing of diabetes mellitus infectious wounds, so that an example is provided for treatment of the complex infectious wounds; and the problem that biological infection treatment is difficult to enter clinical research is solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of medical preparations, and relates to a biological agent, in particular to a kind of antibiotic-loaded nanometer platelet vesicle and its preparation method and application. BACKGROUND

[0002] Infectious wound healing caused by trauma is a major clinical challenge. Traditional systemic antibiotic use can lead to the emergence of multi-drug resistant bacteria, while emerging bioactive material strategies are difficult to enter clinical research due to the lack of in vivo biocompatibility and toxicity studies.

[0003] Platelets, as the key cells of the body's hemostatic response, can rapidly and densely move to the site of tissue trauma, and also participate in the host's innate and adaptive defense against infection. Moreover, platelets have the advantages of biological safety, easy to obtain, large yield, etc., so the platelet-based delivery platform may represent an effective antibacterial approach. However, platelets are more than 1-2 microns in diameter, have different shapes, poor tissue penetration, and low quality uniformity. Moreover, as pro-inflammatory cells, platelets may exacerbate inflammation by releasing inflammatory factors after activation.

[0004] Nanometer platelet vesicles have platelet-like functions, do not need to be synthesized, have minimal natural source toxicity, and have high biocompatibility. As a drug delivery carrier, nanometer platelet vesicles can effectively encapsulate hydrophilic and hydrophobic drugs, and at the nanoscale, can cross biological barriers in the body and maintain long-term circulation. Prior art 1 (CN110090310A) discloses a platelet membrane self-assembled nanobubble for ultrasonic image diagnosis of vascular injury site and its preparation method and application, and prior art 2 (CN110267667A) discloses a method for treating and culturing serum containing growth factors. However, there is a lack of development and utilization of the biological functions of platelets themselves. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides an antibiotic-loaded nanometer platelet vesicle and its preparation method and application, which nanofibrillates platelets based on a mild physical method and loads antibiotics. The antibiotic-loaded nanometer platelet vesicle retains anti-inflammatory related proteins inside the platelets, and also enriches antibacterial and immune-regulating related proteins on the surface of the vesicle. Combined with the sustained-release effect of fibrin gel, the antibiotic-loaded nanometer platelet vesicle can precisely and durably act on the affected area, while accelerating wound repair and closure.

[0006] An antibiotic-loaded nanometer platelet vesicle, wherein the nanometer platelet vesicle is obtained by non-contact ultrasonic and membrane extrusion nanofibrillation of platelets, and is formed by incubation with an antibiotic drug.

[0007] As preferred, the platelets are isolated from autologous venous peripheral blood.

[0008] As preferred, the antibiotic drug is gentamicin, levofloxacin or linezolid.

[0009] A preparation method of antibiotic-loaded nanoplatelet vesicles, platelets are isolated and enriched from autologous venous peripheral blood, then the enriched platelets and antibiotic drugs are loaded into a centrifuge tube, the tube cover is tightly covered and sealed, then placed in the water tank of an ultrasonic instrument, and the non-contact ultrasonic method is used for nanometer treatment, finally the membrane extrusion method is used to obtain the antibiotic-loaded nanoplatelet vesicles.

[0010] As preferred, the volume of the enriched platelets and antibiotic drugs does not exceed 1 / 2~2 / 3 of the total volume of the centrifuge tube.

[0011] As preferred, deionized water or distilled water is added to the water tank of the ultrasonic instrument, and the liquid height is higher than the liquid level in the centrifuge tube, the ultrasonic instrument is set to 30% power, opened for 3s and closed for 2s, and run for 15min, then the sample is taken out and cooled for 1~3min to quickly stop the heat effect.

[0012] As preferred, the antibiotic-loaded nanoplatelet vesicles are obtained by uniform repeated extrusion through an extrusion membrane with a pore size of 0.1~0.3μm.

[0013] As preferred, the platelets are isolated from the venous peripheral blood by differential centrifugation.

[0014] As preferred, the venous peripheral blood is placed in a centrifuge tube, centrifuged at 300×g for 10 minutes, the upper layer of peripheral blood is collected and transferred to a new centrifuge tube, centrifuged at 800×g for 30 minutes, the supernatant is discarded, the lower layer of platelet precipitate is aspirated, and the PBS buffer containing 1μM prostaglandin E1 is blown and mixed to obtain the enriched platelets, and the temperature is adjusted to 25~37℃ and the pH value is adjusted to 7.0~7.4.

[0015] An application of antibiotic-loaded nanoplatelet vesicles, the antibiotic-loaded nanoplatelet vesicles are mixed with fibrinogen and thrombin, and then left to obtain a fibrin gel containing antibiotic-loaded nanoplatelet vesicles, which is used as an antibacterial, endothelial cell proliferation and migration promoting or infectious wound tissue repair drug.

[0016] The present application has the following beneficial effects: 1. By enriching and nanometerizing the platelets to 100~300nm in size, and loading antibiotic drugs, the specific antibiotic loading and sustained release effect is effectively realized.

[0017] 2. The nanometer-sized platelet vesicles enriched with the bacteria-targeting protein (GPIIb) and the immune-regulating protein (GPIb) on the surface by the non-contact ultrasonic nanometerization method can more efficiently target bacteria.

[0018] 3. Compared with platelet membrane vesicles, the nanometer-sized platelet vesicles retain the anti-inflammatory cytokine (platelet factor-4) inside the platelets and have inflammation and immune-regulating functions.

[0019] 4. The antibiotic-loaded nanometer-sized platelet vesicles can be applied in the preparation of drugs for bacterial targeting, inflammation regulation, antibacterial, endothelial cell proliferation and migration, tube formation, and promotion of tissue healing of mouse diabetic infected wounds. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The particle size and potential of the nanometer-sized platelet vesicles (PEVs) and the gentamicin-loaded nanometer-sized platelet vesicles (Gen@PEVs) in Example 1.

[0021] Figure 2 The freeze transmission electron microscopy characterization of the nanometer-sized platelet vesicles (PEVs) and the gentamicin-loaded nanometer-sized platelet vesicles (Gen@PEVs) in Example 1.

[0022] Figure 3 The release results of the gentamicin-loaded nanometer-sized platelet vesicles (Gen@PEVs) in Test Example 1 at different pH values.

[0023] Figure 4 The protein analysis results of the nanometer-sized platelet vesicles (PEVs) and platelets (PLTs) in Test Example 2.

[0024] Figure 5 The targeted bacteria ability test results of the nanometer-sized platelet vesicles (PEVs) in Test Example 2.

[0025] Figure 6 The immune-regulating ability test results in Test Example 3.

[0026] Figure 7 The antibacterial test results in Test Example 3.

[0027] Figure 8 The test results of destroying bacterial biofilms in Test Example 3.

[0028] Figure 9 The test results of endothelial cell proliferation in Test Example 4.

[0029] Figure 10 The test results of endothelial cell scratch in Test Example 4.

[0030] Figure 11To test the results of the vascular endothelial cell tube formation test in Example 4.

[0031] Figure 12 To test the results of the endothelial cell immunofluorescence test in Example 4.

[0032] Figure 13 To test the results of the in vivo test of mouse diabetic wound infection in Example 4.

[0033] Figure 14 To test the results of hematoxylin-eosin staining of mouse diabetic wounds in Example 4. DETAILED DESCRIPTION

[0034] The present application is further explained in conjunction with the accompanying drawings, which are intended to illustrate but not to limit the scope of the present application.

[0035] Example 1 This example provides a method for preparing antibiotic-loaded nanometer-sized platelet vesicles, which uses nanometer-sized platelet vesicles to load gentamicin, and the platelets are derived from the peripheral blood of a living being in need of antibacterial treatment. The specific steps are as follows: Step 1, isolation and enrichment of platelets by differential centrifugation The peripheral blood of a living being in need of antibacterial treatment is placed in a centrifuge tube, and after centrifugation at 300 x g for 10 minutes, the upper layer of peripheral blood containing platelet plasma is collected and transferred to a new centrifuge tube. After centrifugation at 800 x g for 30 minutes, the supernatant is discarded, and the lower layer of platelet sediment is obtained by blowing and mixing with PBS buffer containing 1 μM prostaglandin E1, to obtain enriched platelets (PLTs).

[0036] Step 2, adjustment of platelet environmental conditions The environmental temperature of the platelets is adjusted to 25-37°C, and the pH value is adjusted to 7.0-7.4.

[0037] Step 3, preparation of gentamicin-loaded nanometer-sized platelet vesicles The enriched platelets and gentamicin are loaded into a centrifuge tube, and the volume does not exceed 1 / 2-2 / 3 of the total volume of the centrifuge tube. After tightly covering the tube cap and sealing the sealing film, it is placed in the water tank of the ultrasonic instrument. Deionized water or distilled water is added to the water tank of the ultrasonic instrument to ensure that the liquid level in the water tank is higher than the liquid level in the centrifuge tube. The ultrasonic instrument is set to 30% power, and is operated in a 3 s on and 2 s off mode for 15 min. Then the sample is taken out and cooled on ice for 1-3 min. Finally, the gentamicin-loaded nanometer-sized platelet vesicles (Gen@PEVs) are obtained by repeatedly extruding through a 0.22 μm pore size extrusion membrane at a uniform speed.

[0038] Step 4, preparation of nanometer-sized platelet vesicles The enriched platelets were loaded into centrifuge tubes, and nano-platelet vesicles (PEVs) were prepared using the same non-contact ultrasonic method as in Step 3.

[0039] The nano-platelet vesicles (PEVs) and the gentamicin-loaded nano-platelet vesicles (Gen@PEVs) were respectively placed in a dynamic light scattering analyzer for particle size and potential testing, and the results are shown in Figure 1 The average particle size of the nano-platelet vesicles (PEVs) was 183.5 nm, and the average particle size of the gentamicin-loaded nano-platelet vesicles (Gen@PEVs) was about 202.8 nm. The surface potential ZETA of both was maintained at about -10 mV, indicating that loading the antibiotic drug had little effect on the structure size and surface potential of the nano-platelet vesicles.

[0040] The nano-platelet vesicles (PEVs) and the gentamicin-loaded nano-platelet vesicles (Gen@PEVs) were respectively prepared for cryo-EM sample preparation and observation, and the results are shown in Figure 2 The particle sizes of the two kinds of vesicles were uniform, the morphology was round, and the structure was complete, indicating that the drug-loaded nano-platelet vesicles could still retain the composition and structure of the nano-platelet vesicles.

[0041] Test Example 1 The gentamicin-loaded nano-platelet vesicles (Gen@PEVs) prepared in Example 1 were subjected to ultracentrifugation at 4℃ and 100,000 rpm. After the supernatant was discarded, different pH PBS buffers were added, and the samples were placed in an environment at 37℃. The concentration of gentamicin released into the supernatant was measured within 0-96 hours, and the results are shown in Figure 3 In the PBS buffer with pH=7.4, the effective concentration of gentamicin can be maintained for about 2 days, while in the weakly acidic environment with pH=6.0, the effective concentration of gentamicin can only be maintained for about 6 hours, indicating that the nano-platelet vesicles can achieve long-term effective drug release in a neutral buffer system, and can accelerate the release of gentamicin in an acidic environment such as bacterial infection.

[0042] Test Example 2 Step 1: Proteins were extracted from the nano-platelet vesicles (PEVs) and platelets (PLTs) prepared in Example 1 using RIPA buffer containing 1% protease inhibitor benzylsulfonyl fluoride. The proteins were separated by 10% SDS-PAGE and transferred to a polyvinylidene fluoride membrane. After blocking the membrane with 5% skim milk for 1.5 hours, the membrane was washed with Tris buffer containing Tween-20 and incubated with the primary antibody overnight at 4℃. After washing with TBST, the membrane was incubated with HRP-labeled secondary antibody at room temperature for 1 hour. The bands were visualized using a ChemiDoc Touch imaging system, as shown in Figure 4As shown, compared to platelets (PLTs), nano-platelet vesicles (PEVs) are enriched with bacteria-associated proteins (GPIIb) and immune-regulatory proteins (GPIb), and contain anti-inflammatory associated cytokines (CXCL4).

[0043] Step 2, Staphylococcus aureus and Escherichia coli were cultured in LB broth at 37°C overnight, and labeled with lipophilic dye DiI. The bacteria were washed with sterile PBS buffer and incubated with DiO-labeled nano-platelet vesicles (PEVs) and liposomes (Liposomes) at 37°C for 2 hours, respectively.

[0044] The bacteria were centrifuged at 3000 rpm for 10 minutes to remove unbound vesicles, and fixed with 10% formaldehyde before imaging using a Nikon confocal microscope, as shown in Figure 5 As shown, the percentage of nano-platelet vesicles (PEVs) binding to bacteria was significantly higher than that of liposomes (Liposomes).

[0045] Example 2 This example provides a method for preparing antibiotic-loaded nano-platelet vesicles. The nano-platelet vesicles loaded with gentamicin (Gen@PEVs) prepared in Example 1 were mixed with fibrinogen and thrombin, and left to stand for 10 minutes to obtain a fibrin gel containing nano-platelet vesicles loaded with gentamicin (Gen@PEV-ECM), wherein the volume ratio of fibrinogen to thrombin was 10:1. The fibrin gel containing nano-platelet vesicles loaded with gentamicin (Gen@PEV-ECM) was used as an antibacterial or infected wound tissue repair drug.

[0046] Test Example 3 This test example tests the function of the fibrin gel containing nano-platelet vesicles loaded with gentamicin (Gen@PEV-ECM) as an antibacterial drug: Step 1, the nano-platelet vesicles (PEVs) prepared in Example 1 were mixed with fibrinogen and thrombin, and left to stand for 10 minutes to obtain a fibrin gel containing nano-platelet vesicles (PEV-ECM).

[0047] Step 2, lipopolysaccharide (LPS), lipopolysaccharide + fibrin gel (ECM), fibrin gel containing nano-platelet vesicles (PEV-ECM), and fibrin gel containing nano-platelet vesicles loaded with gentamicin (Gen@PEV-ECM) were used to stimulate bone marrow-derived macrophages (BMDM) for 24 hours, respectively, and the macrophage surface markers F4 / 80 and CD206 were analyzed by flow cytometry, as shown in Figure 6As shown, the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) increased the CD206 + F4 / 80 + The proportion of macrophages (M2 macrophages). It is shown that Gen@PEV-ECM can effectively promote the polarization of macrophages from the pro-inflammatory phenotype to the anti-inflammatory phenotype.

[0048] Step 3, the fibrin gel containing nanoplatelet vesicles (PEV-ECM), the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) were added into three broth suspensions of S. aureus, P. aeruginosa and E. coli respectively as experimental groups, and a blank control group was set.

[0049] After being placed in a 37℃ 210 rpm shaker for 12 hours, 100 μL of broth suspension was gradient diluted and uniformly coated on the surface of LB agarose plates, and after being placed in a 37℃ incubator for 12 hours, the colony forming units (CFU) were counted as Figure 7 As shown, it can be seen that the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) has a significant killing effect on S. aureus, P. aeruginosa and E. coli.

[0050] Step 4, S. aureus, P. aeruginosa and E. coli were spread on the glass slides and placed in a 37℃ incubator for 96 hours, and after the biofilm grew, the fibrin gel containing nanoplatelet vesicles (PEV-ECM), the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) were added as experimental groups, and a blank control group was set.

[0051] After 12 hours of glutaraldehyde fixation, the sample was prepared, and the structure of the three bacterial biofilms was observed by scanning electron microscopy, as shown in Figure 8 As shown, the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) can penetrate the physical barrier on the surface of the biofilm of S. aureus, P. aeruginosa and E. coli, release gentamicin to destroy the biofilm structure, and play a good bactericidal role.

[0052] Test Example 4 This test example tests the function of the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) as an infectious wound tissue repair drug: Step 1, the fibrin gel containing nanoplatelet vesicles (PEV-ECM) and the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) were added to the endothelial cell culture medium, and a blank control group was set.

[0053] After 24 hours, the cell proliferation was determined by crystal violet staining, as shown in Figure 9 The fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) promoted the proliferation of endothelial cells, indicating that it may retain the growth factors and other proteins in platelets.

[0054] Step 2, a scratch treatment was performed in the endothelial cell culture medium to establish a blank area, and the fibrin gel containing nanoplatelet vesicles (PEV-ECM) and the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) were added, respectively, and a blank control group was set.

[0055] After 48 hours, the cell migration rate was analyzed by microscope photography, as shown in Figure 10 The fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) significantly promoted the migration of endothelial cells within 48 hours, indicating that it may retain some chemotactic factors and other proteins in platelets.

[0056] Step 3, the endothelial cells were cultured on Matrigel, and the fibrin gel containing nanoplatelet vesicles (PEV-ECM) and the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) were added, respectively, and a blank control group was set.

[0057] After continuing to culture for 4-6 hours, the differentiation of cells into rings was observed, as shown in Figure 11 The fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) promoted the formation of vascular rings in endothelial cells, indicating that the nanoplatelet vesicle gel retained the vascularization proteins on the surface of platelets and could promote vascular formation.

[0058] After 12 hours of culture, the cells were fixed, permeabilized, blocked, incubated with primary antibody CD31 and fluorescent secondary antibody, and stained with DAPI, and the expression level of platelet-adhesion molecule CD31 on the surface of endothelial cells was observed by confocal microscopy, as shown in Figure 12As shown, the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) significantly promoted the expression level of platelet-adhesion molecule CD31 on the surface of endothelial cells, indicating that the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) can promote vascular adhesion and generation.

[0059] Step 4, a 6mm size wound was established on the back of the STZ-induced diabetic mice, and the fibrin gel containing nanoplatelet vesicles (PEV-ECM) and the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) were respectively applied externally, and a blank control group was set.

[0060] The wound changes on day 0-14 were counted, such as Figure 13 As shown, the wound healing condition of the group using the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) was obviously better than that of the other two groups on day 14, indicating that the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) can play an ideal role in promoting the repair of diabetic infected wounds.

[0061] On day 7 and day 14, the wound tissues of the three groups of mice were taken for hematoxylin-eosin staining, and the sections were observed, such as Figure 14 As shown, the use of the fibrin gel containing gentamicin-loaded nanoplatelet vesicles (Gen@PEV-ECM) can more quickly and better promote the healing of diabetic infected wounds.

[0062] Example 3 The present embodiment provides a preparation method of antibiotic-loaded nanoplatelet vesicles. On the basis of Example 1, the enriched platelets and levofloxacin are loaded into a centrifuge tube, and after frequent non-contact ultrasonic treatment, the nanoplatelet vesicles loaded with levofloxacin are obtained by repeatedly extruding at a constant speed through an extrusion membrane with a pore size of 0.1μm.

[0063] Example 4 The present embodiment provides a preparation method of antibiotic-loaded nanoplatelet vesicles. On the basis of Example 1, the enriched platelets and linezolid are loaded into a centrifuge tube, and after frequent non-contact ultrasonic treatment, the nanoplatelet vesicles loaded with linezolid are obtained by repeatedly extruding at a constant speed through an extrusion membrane with a pore size of 0.3μm.

[0064] The above merely describes the preferred embodiments of the present application. It should be noted that although the present application has been described in detail through the above preferred embodiments, those skilled in the art should understand that, without departing from the principles of the present application, several improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application, without deviating from the scope defined by the claims of the present application.

Claims

1. An antibiotic-loaded nanoplatelet vesicle, characterized by: The nanoplatelet vesicles are obtained by performing non-contact ultrasound and membrane extrusion nano-processing on platelets, and are incubated with antibiotic drugs to form antibiotic-loaded nanoplatelet vesicles.

2. The antibiotic-loaded nanoplatelet vesicle according to claim 1, characterized in that: The platelets are separated from autologous venous peripheral blood.

3. The antibiotic-loaded nanoplatelet vesicle according to claim 1, characterized in that: The antibiotic drug is gentamicin, levofloxacin or linezolid.

4. The method for preparing an antibiotic-loaded nanoplatelet vesicle according to any one of claims 1 to 3, characterized in that: Platelets are separated and enriched from autologous venous peripheral blood, and then the enriched platelets and antibiotics are placed in a centrifuge tube. After the tube is tightly capped and sealed, it is placed in the water tank of an ultrasound instrument and nano-processed by non-contact ultrasound. Finally, antibiotic-loaded nanoplatelet vesicles are obtained by membrane extrusion.

5. The method for preparing antibiotic-loaded nanoplatelet vesicles according to claim 4, characterized in that: The volume of the enriched platelets and antibiotics is 1 / 2 to 2 / 3 of the total volume of the centrifuge tube.

6. The method for preparing antibiotic-loaded nanoplatelet vesicles according to claim 4, wherein: Add deionized water or distilled water to the ultrasonic instrument water tank so that the liquid level is higher than the liquid level in the centrifuge tube. Set the ultrasonic instrument to 30% power, turn on for 3 seconds and off for 2 seconds, and run for 15 minutes.

7. The method for preparing antibiotic-loaded nanoplatelet vesicles according to claim 5, characterized in that: After the sonication operation is completed, remove the sample and place it on ice to cool.

8. The method for preparing antibiotic-loaded nanoplatelet vesicles according to claim 4, wherein: Platelets were isolated from venous peripheral blood by differential centrifugation.

9. The method for preparing antibiotic-loaded nanoplatelet vesicles according to claim 8, characterized in that: Place venous peripheral blood in a centrifuge tube, centrifuge at 300×g for 10 minutes, collect the upper layer of peripheral blood, transfer to a new centrifuge tube, centrifuge at 800×g for 30 minutes, discard the supernatant, aspirate the lower layer of platelet precipitate, and mix by pipetting with PBS buffer containing 1μM prostaglandin E1 to obtain enriched platelets.

10. The use of the antibiotic-loaded nanoplatelet vesicles according to any one of claims 1 to 3, characterized in that: The antibiotic-loaded nanoplatelet vesicles are mixed with fibrinogen and thrombin and then allowed to stand to obtain a fibrin gel containing the antibiotic-loaded nanoplatelet vesicles, which can be used as an antibacterial drug, a drug that promotes endothelial cell proliferation and migration, or a drug that repairs infectious wound tissue.

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