CN117122697A - Sialic acid modified gradient liposome, vincristine sulfate liposome preparation, preparation method and application - Google Patents

Abstract

Sialic acid modified gradient liposome, vincristine sulfate liposome preparation, preparation method and application thereof, and the technical field of liposome preparation methods. The sialic acid modified gradient liposome is prepared by taking sphingomyelin and cholesterol as liposome membrane materials, taking sialic acid-cholesterol conjugate (SA-CH) as a targeting group, taking SOS-TEA solution as a hydration medium solution and adopting a sucrose octasulfate triethylamine gradient method. The sialic acid modified gradient liposome is used as a carrier to obtain the vincristine sulfate liposome preparation. The vincristine sulfate liposome preparation has the advantages of strong tumor targeting, excellent in vivo anti-tumor curative effect, good placement stability and the like, and solves the problems of poor placement stability, lack of tumor targeting and the like of VCR liposome prepared by the current pH gradient method.

Description

Sialic acid modified gradient liposome, vincristine sulfate liposome preparation, preparation method and application

Technical Field

The invention relates to the technical field of liposome preparation methods, in particular to sialic acid modified gradient liposome, a vincristine sulfate liposome preparation, a preparation method and application thereof.

Background

Tumor development is not only caused by the change in the nature of tumor cells, but the tumor-associated immune cell population within the tumor immune microenvironment (Tumor immune microenvironment, TIME) is also an active participant. These tumor-associated immune cells can help tumor cells shape the immunosuppressive microenvironment, thereby evading immune system recognition and promoting tumor growth. Tumor-associated macrophages (Tumor associated macrophages, TAMs) are the most abundant tumor-associated immune cell population in TIME, and refer to macrophages that infiltrate within and around the tumor. The amount of TAMs infiltrated in a tumor is closely related to the poor prognosis of the patient. Thus, targeted therapeutic strategies against TAMs are expected to address the problem of tumor treatment from the source.

Sialic Acid (SA) is a family of nine carbon Acid amino sugars common to all vertebrates and some invertebrates. Excessive sialylation and heterosialylation can help tumor cells escape immune recognition, promoting tumor progression. The highly expressed sialoglycan on the surface of tumor cells binds to sialic acid receptor to evade immune surveillance. Among them, sialic acid binds to immunoglobulin-like receptors (Siglecs) as a class of SA recognition receptors, is widely expressed on the surface of immune cells, and plays an important role in maintaining immune homeostasis and regulating inflammatory reaction. The sialic acid-cholesterol conjugate is modified on the surface of the liposome, so that the tumor active targeting capability of the liposome can be effectively improved, tumor-related immune cells such as TAMs and the like are killed, TIME is remodelled, and the anti-tumor immune response of the organism is recovered.

Vincristine sulfate (Vincristine Sulfate, VCR) is a cell cycle dependent antitumor drug that binds to tubulin and causes microtubule depolymerization, metaphase arrest and apoptosis. Meanwhile, VCRs can have an effect on immune cells of the organism, for example, they can induce maturation of Dendritic Cells (DCs) in vitro, secrete IL-1β, IL-6 and IL-12, enhance the ability to activate cytotoxic T cells (Cytotoxic T lymphocytes, CTLs) (TANAKA H, MATSUSHIMA H, NISHIBU A, et al.Dual therapeutic efficacy of vinblastine as a unique chemotherapeutic agent capable of inducing Dendritic cell maturation [ J ]. Cancer research.2009,69 (17): 6987-6994.). VCR can also induce macrophage transformation to M1 subtype, up-regulate secretion of pro-inflammatory cytokines such as IL-6, IL-1 beta, TNF-alpha (GAO Y, teng Y, ZHANG H, et al vincristine leads to colonic myenteric neurons injury via pro-inflammatory macrophages activation [ J ]. Biochemistry pharmaceutical 2021,186:114479 ]) (FUJIMURA T, KAKIZAKI a, KAMBAYASHI Y, et al cytotoxic antimelanoma drugs suppress the activation of M2 macro [ J ]. Experimental demamachine [ 2018,27 (1): 64-70 ]). In addition, microtubule-associated drugs such as VCR induce DNA lesions in a variety of ways that the body recognizes and activates adaptive immunity, promote infiltration of CTLs into tumor sites, enhance anti-tumor immune responses (SERPICO AF, viscoti R, groco d. Stimulating immune-dependent effects of microtubule-targeting agents to improve efficacy and tolerability of cancer treatment [ J ]. Cell Death & disease.2020,11 (5): 361-367 ]) (MITCHISON T J, PINEDA J, SHI J, et al is inflammatory micronucleation the key to asuccessful anti-mitotic cancer drug.

In 2012, vincristine sulfate liposome injection (Vincristine sulfate liposome injection, VSLI) produced by us Talon Therapeutics company was approved by FDA for marketing under the trade name ofMainly for treating Philadelphia chromosome negative (Ph) ^- ) Adult patients with acute lymphoblastic leukemia.The lipid composition of the prescription is Sphingomyelin (SM) and Cholesterol (CH), and the proportion is 60 according to the mole ratio: 40, the average grain diameter is about 100nm, the medicine is carried by a pH gradient method, the medicine encapsulation efficiency can reach more than 95 percent (SILVERMAN J A, DEITCHER S R. & gt>(vincristine sulfate liposome injection)improves the pharmacokinetics and pharmacodynamics of vincristine[J].Cancer Chemotherapy and Pharmacology.2013,71(3):555-564.)(MAO W,WU F,LEE R J,et al.Development of a stable single-vial liposomal formulation for vincristine[J]International Journal of nanomedicine.2019,14 (1): 4461-4474.). However, such VCR liposome formulations present several challenges. VCR is a very membrane permeable drug (logp=2.82), which is prone to leakage from liposomes and has poor in vivo and in vitro stability (WANG X, SONG Y, SU Y, et al are PEGylated liposomes better than conventional liposomesA special case for vincristine [ J)]Drug delivery.2016,23 (4): 1092-1100.). Researchers have attempted to encapsulate VCRs in pegylated liposomes, which has shown to result in rapid leakage of VCRs in vivo, with lower efficacy than conventional SM/CH liposomes. Thus (S) >Packaging with 3 bottles using conventional SM/CH liposome as carrier to ensure stability of the preparation (YANG Y, GUO Y, TAN X, et al Vincristine-loaded liposomes prepared by ion-paring techniques: effect of lipid, pH and antioxidant on chemical stability [ J)]European Journal of Pharmaceutical sciences.2018, 111:104-112.). The three-bottle VCR liposome is required to be prepared in situ in application, has complicated process, and must be carried out in a biosafety cabinet or according to the established pharmacy safety procedures, which has extremely high requirements on environment and operators (MAO W, WU F, LEE R J, et al development of a stable single-vial liposomal formulation for vincristine [ J)]International Journal of nanomedicine.2019,14 (1): 4461-4474.). Furthermore, the->Targeting of tumors depends primarily on their passive accumulation at the tumor site. Therefore, there is a need to develop a more stable VCR liposome formulation with active targeting ability to tumors to improve its therapeutic effect and reduce toxic and side effects.

Disclosure of Invention

Aiming at the problems existing in the prior art, the invention provides a sialic acid modified gradient liposome, a vincristine sulfate liposome preparation, a preparation method and application thereof, wherein the preparation method is a sucrose octasulfate triethylamine gradient method, so as to obtain the sialic acid modified gradient liposome, and the sialic acid modified gradient liposome is used as a carrier, so that the vincristine sulfate liposome preparation has the advantages of strong tumor targeting, excellent in-vivo anti-tumor curative effect, good placement stability and the like, and solves the problems of poor placement stability, lack of tumor targeting and the like of VCR liposome prepared by the conventional pH gradient method. The sialic acid-cholesterol conjugate is used for modifying liposome, so that the accumulation of the preparation on tumor sites and the inhibition effect on tumor-related immune cells are improved, the anti-tumor immune response of an organism is activated, and the curative effect of the medicine is improved.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

a sialic acid modified gradient liposome uses sphingomyelin and cholesterol as liposome membrane material, sialic acid-cholesterol conjugate (SA-CH) as targeting group, and sucrose octasulfate triethylamine (SOS-TEA) solution as hydration medium solution.

Further, according to the mole ratio, sphingomyelin: cholesterol: sialic acid-cholesterol conjugate= (50-60): (35-45): (2-10).

According to the mass ratio, sphingomyelin: SOS-TEA= (1-5) in hydration medium solution: 8.

the sialic acid-cholesterol conjugate (SA-CH) has the structure:

the vincristine sulfate liposome preparation takes vincristine sulfate as a medicine and sialic acid modified gradient liposome as a carrier; wherein, according to the mass ratio of the medicine to the fat, vincristine sulfate: sphingomyelin = 1 in sialic acid modified gradient liposomes: (5-20), preferably 1:10.

The encapsulation rate of the vincristine sulfate liposome preparation is more than 95%, the particle size is between 100 and 110nm, the polydispersity coefficient is 0.01 to 0.04, and the zeta potential is-20 mV to-30 mV.

The invention provides a preparation method of sialic acid modified gradient liposome, which adopts a sucrose octasulfate triethylamine (SOS-TEA) gradient method.

In the sucrose octasulfate triethylamine (SOS-TEA) gradient method, the anionic sucrose octasulfate in the hydration medium solution is a polysulfonic compound with high charge density, and can form insoluble aggregates with the cationic drug vincristine sulfate in an internal water phase, so that the retention capacity of the drug in the internal water phase of the liposome is improved, and the leakage of the drug is reduced.

The preparation method of sialic acid modified gradient liposome specifically comprises the following steps:

(1) Preparing hydration medium solution

Weighing sucrose octasulfate, and adding distilled water for dissolution to obtain sucrose octasulfate solution; passing through a strong acid hydrogen type cation exchange resin column to convert sucrose octasulfate into free acid to obtain SOS solution;

regulating the pH value of the SOS solution to 6.0+/-0.5 by using triethylamine, fixing the volume, uniformly mixing, and sterilizing by using a filtering membrane to obtain the SOS-TEA solution, namely a hydration medium solution; wherein, in the SOS-TEA solution, the molar concentration of SOS-TEA is 50mmol/L to 250mmol/L, preferably 100mmol/L;

(2) Preparation of blank liposomes

Weighing liposome membrane materials and targeting groups, adding absolute ethyl alcohol, and stirring and dissolving completely at 60-80 ℃ to obtain membrane material solution; continuously stirring, volatilizing absolute ethanol to obtain membrane material concentrated solution; the liposome membrane material is sphingomyelin and cholesterol, and the targeting group is sialic acid-cholesterol conjugate; sphingomyelin in molar ratio: cholesterol: sialic acid-cholesterol conjugate= (50-60): (35-45): (2-10);

Preheating a hydration medium solution to the same temperature as the membrane material concentrated solution, then mixing the hydration medium solution and the membrane material concentrated solution, and stirring at 60-80 ℃ to obtain a blank liposome primary product;

extruding the blank liposome primary product through polycarbonate membranes with different pore diameters at 60-80 ℃ to obtain blank liposome suspension;

(3) Preparation of gradient liposomes

And (3) removing the outer aqueous phase hydration medium solution from the blank liposome suspension, and establishing a liposome transmembrane ion gradient to obtain sialic acid modified gradient liposome.

In the step (1), the strong acid hydrogen type cation exchange resin column is preferably 732 type hydrogen cation exchange resin column.

In the step (1), the filter membrane is preferably a microporous filter membrane of 0.22 μm.

In the step (2), SOS-TEA in a hydration medium solution is prepared according to the mass ratio: sphingomyelin in membrane concentrate = 8: (1-5).

In the step (2), the concentration of the catalyst is 5-10 mL.min ^-1 The hydration medium solution is added to the membrane concentrate.

In the step (2), the liposome is extruded, the extrusion pressure is 100 kPa-500 kPa, the aperture of the polycarbonate membrane with different aperture adopted by extrusion is 80 nm-400 nm, each aperture passes 5-10 times, and the aperture passes from large to small.

In the step (3), the sialic acid modified gradient liposome forms a pH gradient between the inner and outer aqueous phases of the liposome and the inner and outer membrane, which is formed by diffusion of triethylamine in the hydration medium solution. The pH gradient difference is 3-4.

In the step (3), the method for establishing the liposome transmembrane ion gradient is any one or more of ion exchange method, dialysis method and gel filtration method to remove the hydration medium solution in the aqueous phase outside the liposome, preferably dialysis method.

The dialysis method adopts a dialysis medium, preferably sucrose solution with the mass concentration of 5% -15%, and the time for changing the dialysis medium at intervals is 30-60 min, and the dialysis time is 1.5-2.5 h, preferably 2h in the dialysis process.

The preparation method of the vincristine sulfate liposome preparation comprises the following steps:

mixing sialic acid modified gradient liposome and vincristine sulfate drug solution, incubating drug loading at 55-80 ℃ for 10-60 min, preferably at 60-75 ℃ for 40-60 min, more preferably at 70 ℃ for 50min, and stopping drug loading in ice water bath to obtain vincristine sulfate liposome preparation; wherein, according to the mass ratio, vincristine sulfate medicine: sphingomyelin = 1 in sialic acid modified gradient liposomes: (5-20), preferably 1:10.

The vincristine sulfate liposome preparation is used for preparing antitumor drugs.

The sialic acid modified gradient liposome, the vincristine sulfate liposome preparation, the preparation method and the application thereof have the beneficial effects that:

1. the invention prepares the gradient liposome modified by sialic acid by a sucrose octasulfate triethylamine gradient method for the first time, and prepares the vincristine sulfate liposome preparation by taking the gradient liposome modified by sialic acid as a carrier and vincristine sulfate as a medicament, and the preparation shows good in-vivo and in-vitro stability, tumor active targeting and excellent anti-tumor effect through verification.

2. Most importantly, the invention unexpectedly discovers that the vincristine sulfate liposome preparation prepared by the invention is used as an anti-tumor drug, and has the phenomenon that tumor tissues are 'shed' from a growth part, and no tumor recurrence sign exists within 3 months. After 3 months, the recovered tumor "shedding" mice secondarily bear tumors, and the phenomenon of tumor "shedding" occurs again under the condition of no administration. This suggests that its superior anti-tumor effect is not only dependent on killing tumor cells, but also is related to its altered tumor immune microenvironment, inducing a strong anti-tumor immune response in the body. This result will turn over the understanding of traditional chemotherapeutics, and in the course of tumor treatment, the immune system of the organism is placed in a more important position, and only if the drugs and the immune system of the organism are placed in the same battle line, the drugs and the immune system of the organism can cooperatively play the role of resisting tumor, so that the tumor can be more effectively resisted.

3. The invention selects sphingomyelin, which is one of main lipid components of animal cell membranes, and is connected only through amide bond and ether bond, so that the sphingomyelin has lower sensitivity to acid and enzyme degradation and is more hydrolysis-resistant compared with other lipid membranes. The sphingomyelin bilayer membrane has small molecular distance, low membrane fluidity, high saturation of a hydrophobic region, hydrogen bond donors and hydrogen bond acceptors exist in the structure at the same time, and stronger interaction force with cholesterol is achieved, so that more stable liposome can be formed, and leakage of internal medicines is reduced.

Drawings

FIG. 1 is a transmission electron microscope image of each vincristine sulfate liposome formulation;

FIG. 2 is an in vitro release profile of each vincristine sulfate liposome formulation;

FIG. 3 is a graph showing the stability of each vincristine sulfate liposome formulation upon placement;

FIG. 4 is a flow cytometer analysis of uptake of liposomes in mouse leukemia cells (RAW 264.7);

FIG. 5 is a laser confocal microscope analysis of liposome uptake in mouse leukemia cells (RAW 264.7);

FIG. 6 shows the distribution of liposomes in S180 tumor-bearing mice;

FIG. 7 shows the in vivo pharmacokinetic behavior of Wistar rats for each vincristine sulfate liposome formulation;

FIG. 8 is a graph of S180 tumor growth curve of tumor-bearing Kunming mice;

FIG. 9 is a graph of S180 tumor-bearing Kunming mice weight change;

FIG. 10 is a view of the main organs and tumor pathological sections of S180 tumor-bearing Kunming mice;

FIG. 11 shows proliferation of tumor tissue cells in mice;

FIG. 12 shows the tumor tissue tumor-associated macrophage infiltration of mice;

FIG. 13 shows cytotoxic T cell infiltration of mouse tumor tissue;

FIG. 14 is a graph showing the tumor shedding of S180 tumor-bearing Kunming mice;

FIG. 15 shows the secondary shedding of tumors from S180 tumor-bearing Kunming mice.

Detailed Description

The present invention will be described in further detail with reference to examples.

The equipment and reagents used in the examples below are all commercially available.

Sialic acid-cholesterol conjugate (SA-CH, cf. Patent application No. 201610533120.7, patent name: synthesis of a lipid derivative containing sialic acid group, use in pharmaceutical preparation, preparation of Neu5Ac-AE-AC-CH by the method disclosed in the preparation of the same)

Example 1 a method for preparing sialic acid modified gradient liposomes, comprising the steps of:

(1) Preparing hydration medium solution

Weighing sucrose octasulfate potassium, adding distilled water, and performing ultrasonic dissolution to obtain sucrose octasulfate potassium solution; passing through 732 type hydrogen cation exchange resin column, and converting sucrose octasulfate potassium into free acid to obtain SOS solution;

Regulating the pH value of the SOS solution to 6.0 by using triethylamine, fixing the volume, uniformly mixing, and sterilizing by using a microporous filter membrane with the thickness of 0.22 mu m to obtain the SOS-TEA solution, namely a hydration medium solution;

(2) Preparation of blank liposomes

In order to avoid the influence of organic solvent in the preparation process, absolute ethyl alcohol is adopted to dissolve liposome membrane materials, and an ethanol injection method is improved to prepare blank liposome;

prescription of liposome membrane material for blank liposome

Sphingomyelin (SM) 200mg

Cholesterol (CH) 66.52mg

Sialic acid-cholesterol conjugate (SA-CH) sphingomyelin mole 5%

Sialic acid-cholesterol conjugate (SA-CH), 200mg SM and 66.52mg CH were precisely weighed into a penicillin bottle, 500. Mu.L of absolute ethanol was added and dissolved in a 70℃water bath with stirring. After the membrane material is completely dissolved, continuing stirring and volatilizing most of ethanol until the solution is sticky, so as to obtain membrane material concentrated solution;

at 5 mL/min ^-1 The sucrose octasulfate triethylamine (SOS-TEA) solution preheated to the same temperature is injected into the membrane material concentrated solution, and the solution is stirred in a water bath at 70 ℃ for 1h to obtain a blank liposome primary product.

Extruding the blank liposome primary product with a liposome extruder TBX-001 at 70deg.C in sequence through polycarbonate film of 400nm, 200nm, 100nm and 80nm for 10 times, to obtain blank liposome suspension (sphingomyelin concentration 40 mg/mL) ^-1 )。

(3) Sialic acid modified gradient liposome gradient establishment

Taking 2mL of blank liposome suspension, adding the blank liposome suspension into a dialysis bag, changing the dialysis medium once per hour for dialysis for 2 hours, wherein the dialysis medium is sucrose solution with the mass concentration of 10% which is 250 times of the volume of the blank liposome suspension, and obtaining the sialic acid modified gradient liposome.

Example 2

Drug loading: mixing sialic acid modified gradient liposome of the example 1 with VCR drug solution according to a certain ratio, stirring in water bath at 70deg.C, incubating for 50min, taking out, and stopping drug loading in ice water bath for 2min to obtain vincristine sulfate liposome preparation (marked as VCR-SSAL) prepared by SOS-TEA gradient method.

Example 3 optimization of Process

(1) Effect of hydration Medium concentration on vincristine sulfate Liposome preparation encapsulation Rate

SOS-TEA solutions with concentrations of 50mmol/L, 100mmol/L, 150mmol/L, 200mmol/L, 250mmol/L and pH 6.0 were selected, blank liposomes were prepared as described in "example 1", sialic acid modified gradient liposomes were prepared as described in "example 2", with a ratio of drug to lipid of 1:10 (w/w) carrying out drug loading, and determining the encapsulation efficiency of the vincristine sulfate liposome preparation. The results are shown in Table 1.

TABLE 1 Effect of hydration Medium concentration on encapsulation efficiency of vincristine sulfate Liposome formulations

The results show that the encapsulation efficiency of the vincristine sulfate liposome preparation is highest when the concentration of the hydration medium is 100mmol/L, so that the concentration of the hydration medium is selected to be 100mmol/L.

(2) Effect of dialysis time on encapsulation efficiency of vincristine sulfate liposome preparation

SOS-TEA solution with the concentration of 100mmol/L, pH 6.0.0 is used as a hydration medium, blank liposome is prepared according to the method of 'example 1', and outer water phases are removed by dialysis for 1h, 2h, 3h and 4h respectively, so as to obtain sialic acid modified gradient liposome, and the sialic acid modified gradient liposome is prepared according to the ratio of medicine to lipid of 1:10 (w/w) carrying out drug loading, and determining the encapsulation efficiency of the vincristine sulfate liposome preparation. The effect of dialysis time on the encapsulation efficiency of vincristine sulfate liposome preparation is shown in table 2.

TABLE 2 influence of dialysis time on encapsulation efficiency of vincristine sulfate liposome preparation

The results show that the encapsulation efficiency is highest when the water is dialyzed for 2 hours, the ammonium ion gradient formed by triethylamine in the inner and outer water phases is not completely established when the water is dialyzed for 1 hour, so that the encapsulation efficiency is lower, and the inner water phase can leak when the water is dialyzed for more than 2 hours, so that the encapsulation efficiency is reduced. Thus, dialysis was finally selected for 2 hours to remove SOS-TEA liberated from the outer aqueous phase, and a pH gradient was established, with a pH gradient difference of 3.

(3) Effect of drug-to-lipid ratio on encapsulation efficiency of vincristine sulfate liposome preparation

A blank liposome was prepared by the method described in "example 1" using SOS-TEA solution with a concentration of 100mmol/L, pH 6.0.0 as hydration medium, and dialyzing for 2 hours to remove the outer aqueous phase to obtain sialic acid modified gradient liposome according to a ratio of drug to lipid of 1: 5. 1: 10. 1: 15. 1:20 (w/w) carrying out drug loading, and measuring the encapsulation efficiency of the vincristine sulfate liposome preparation, and the result is shown in Table 3.

TABLE 3 Effect of drug-to-lipid ratio on encapsulation efficiency of vincristine sulfate liposome formulations

The result shows that when the medicine-fat ratio is 1:5 to 1: and 10, the encapsulation efficiency of the vincristine sulfate liposome preparation is obviously increased, the medicine-lipid ratio is continuously reduced, and the encapsulation efficiency of the vincristine sulfate liposome preparation is not obviously changed. Thus, from the delivery efficacy, 1 is selected: 10 (w/w) as the final ratio of drug to lipid.

(4) Influence of drug loading time on encapsulation efficiency of vincristine sulfate liposome preparation

A blank liposome was prepared by the method described in "example 1" using SOS-TEA solution with a concentration of 100mmol/L, pH 6.0.0 as hydration medium, and dialyzing for 2 hours to remove the outer aqueous phase to obtain sialic acid modified gradient liposome according to a ratio of drug to lipid of 1:10 (w/w) the drug solution was mixed with sialic acid modified gradient liposomes, incubated at 70℃for 10, 20, 30, 40, 50, 60min, ice water bath for 2min to terminate drug loading, and the encapsulation efficiency was determined for vincristine sulfate liposome formulations, with the results shown in Table 4.

TABLE 4 influence of drug loading time on encapsulation efficiency of vincristine sulfate liposome formulations

The results show that the encapsulation efficiency gradually increases with the prolonged drug loading time. The encapsulation efficiency is highest when the medicine carrying time is 50min, the medicine carrying time is prolonged continuously, and the encapsulation efficiency is reduced to some extent. Thus, 50min was finally selected as the drug loading time for vincristine sulfate liposome formulations.

(5) Influence of drug loading temperature on encapsulation efficiency of vincristine sulfate liposome preparation

A blank liposome was prepared by the method described in "example 1" using SOS-TEA solution with a concentration of 100mmol/L, pH 6.0.0 as hydration medium, and dialyzing for 2 hours to remove the outer aqueous phase to obtain sialic acid modified gradient liposome according to a ratio of drug to lipid of 1:10 (w/w) the drug solution was mixed with gradient liposomes, incubated at 55, 60, 65, 70, 75, 80 ℃ for 50min, ice water bath for 2min to terminate drug delivery, and the encapsulation efficiency was determined for vincristine sulfate liposome formulations, with the results shown in table 5.

TABLE 5 influence of drug loading temperature on encapsulation efficiency of vincristine sulfate liposome formulations

The result shows that the encapsulation rate of VCR liposome is greatly influenced by temperature, and the encapsulation rate of the liposome is gradually increased along with the temperature rise, and the encapsulation rate of the vincristine sulfate liposome preparation is highest when the temperature reaches 70 ℃; the temperature continues to rise and the encapsulation efficiency decreases. Therefore, 70℃was chosen as the optimal drug loading temperature.

EXAMPLE 4 preparation of SOS-TEA gradient drug-loaded sialic acid modified vincristine sulfate Liposome preparation (VCR-SSAL)

By way of the above example, the optimal process for preparing vincristine sulfate liposome formulations (VCR-SSAL) by SOS-TEA gradient drug loading has been identified. On the basis, sialic acid-cholesterol conjugate (SA-CH) with a molar ratio of 5% is modified on the surface of vincristine sulfate liposome, and the specific method comprises the following steps: taking absolute ethyl alcohol as a reaction solvent, taking SOS-TEA solution with the pH of 6.0 and 100mmol/L as a hydration medium, and SM: CH: the feeding mole ratio of SA-CH is 60:35: a blank liposome was prepared by water bath at 5,70 ℃ for 1 h. 10% sucrose is used as a dialysis medium, and the external water phase is removed by dialysis for 2 hours to prepare the gradient liposome, wherein the medicine-fat ratio is 1:10 And (w/w), incubating at 70 ℃ for 50min, loading VCR, and stopping drug loading in ice water bath for 2min to obtain the sialic acid modified vincristine sulfate liposome preparation (marked as VCR-SSAL) prepared by carrying the drug by an SOS-TEA gradient method. Particle size, zeta potential and encapsulation efficiency were measured and the results are shown in Table 6.

TABLE 6 characterization of VCR-SSAL

Comparative example 1

A gradient liposome is prepared, which is the same as in example 1, except that a liposome membrane material is adopted, the prescription does not comprise sialic acid-cholesterol conjugate (SA-CH), a liposome without sialic acid modification is obtained, and the liposome without sialic acid modification is adopted as a carrier for carrying out medicine, so that a vincristine sulfate liposome preparation (marked as VCR-SCL) is obtained.

Comparative example 2 validation of optimization Process of vincristine sulfate Liposome formulation (VCR-SCL) prepared by SOS-TEA gradient method

From the results of example 3 above, the optimization procedure for determining the SOS-TEA gradient drug loaded vincristine sulfate liposome formulation (VCR-SCL) was: absolute ethyl alcohol is used as a reaction solvent, a SOS-TEA solution with the pH of 6.0 and the concentration of 100mmol/L is used as a hydration medium, and the feeding mole ratio of SM/CH is 60:40 Blank liposomes were prepared in a water bath at 70℃for 1 h. 10% sucrose is used as a dialysis medium, and the external water phase is removed by dialysis for 2 hours to prepare the gradient liposome, wherein the medicine-fat ratio is 1:10 (w/w), incubation at 70℃for 50min loaded with VCR and ice-water bath for 2min terminated drug loading.

To verify this optimization process, three batches of liposome formulations were prepared using this process and the particle size, zeta potential and encapsulation efficiency were measured and the results are shown in table 7.

Table 7 process verification

The results show that the particle size of the three batches of vincristine sulfate liposome preparations prepared by the process is 100-110 nm, the sizes are uniform, the Zeta potentials are-20 to-30 mV, and the encapsulation rates are more than 95%, which indicates that the preparation process is mature.

Comparative example 3

The vincristine sulfate liposome preparation is the same as that of the embodiment 1 and the embodiment 2, and is different in that the adopted sphingomyelin is replaced by distearoyl phosphatidylcholine and distearoyl phosphatidylglycerol, and the encapsulation rate is reduced by 15% -25% within one month through verification, so that the liposome preparation can not meet the requirements, and only when the sphingomyelin is taken as a main membrane material, the stability of the liposome preparation can be effectively improved, and the leakage of the medicine is reduced.

Comparative example 4

The vincristine sulfate liposome preparation is the same as in example 1 and example 2, except that sialic acid-cholesterol conjugate (SA-CH) is replaced by sialic acid-octadecanoic acid conjugate (MT-18) and sialic acid-octadecylamine conjugate (SA-ODA), and the encapsulation efficiency is reduced by 10% -20% and 10% -20% respectively within one month, which is not satisfactory. It is shown that sialic acid derivatives inserted into liposome membrane material at the carbon chain end can damage the stability of phospholipid bilayer, resulting in faster drug leakage, while sialic acid-cholesterol conjugate (SA-CH) does not damage the stability of phospholipid bilayer.

Comparative example 5 preparation of drug-loaded vincristine sulfate liposome preparation by pH gradient method

In order to examine whether the SOS-TEA gradient method drug-loaded liposome can effectively improve the stability of the vincristine sulfate liposome preparation, two vincristine sulfate liposome preparations (sialic acid modified/sialic acid unmodified) of the pH gradient method drug-loaded are prepared as a control.

Liposome formulations are described in "example 1" and "example 4", and the specific methods are as follows:

precisely weighing liposome membrane material in penicillin bottle, adding 500 μl of absolute ethanol, and stirring in 70deg.C water bath for dissolving. After the membrane material is completely dissolved, continuing stirring and volatilizing most of ethanol until the solution is sticky, so as to obtain membrane material concentrated solution;

At 5 mL/min ^-1 And (3) injecting the citric acid-sodium citrate buffer solution preheated to the same temperature into the membrane material, and stirring in a water bath at 70 ℃ for 1h to obtain a blank liposome primary product.

Sequentially extruding the blank liposome primary product through polycarbonate membranes of 10 times 400nm, 10 times 200nm, 10 times 100nm and 5 times 80nm under 70 ℃ water bath condition to obtain blank liposome suspension (sphingomyelin concentration is 40 mg.mL) ^-1 )。

Taking a proper amount of blank liposome suspension, adding 500mmol/L sodium phosphate solution to adjust the pH of the outer water phase of the blank liposome to 7.0, and uniformly mixing to obtain the gradient liposome.

Gradient liposome is prepared according to a medicine-fat ratio of 1:10 Mixing (w/w) with VCR solution, stirring in water bath at 70deg.C, incubating for 20min, taking out, and ice-water bathing for 2min to stop drug loading to obtain common VCR liposome preparation (marked as VCR-PCL) and SA modified VCR liposome preparation (marked as VCR-PSAL) with pH gradient method drug loading. Particle size, zeta potential and encapsulation efficiency were measured and the results are shown in Table 8.

Table 8 characterization of VCR-PCL and VCR-PSAL

Electron transmission microscopy of four VCR liposomes prepared according to the procedure described in the examples above is shown in FIG. 1.

Example 5 in vitro Release investigation of vincristine sulfate Liposome formulations (FIG. 2)

The drug release of the four vincristine sulfate liposome formulations was analyzed by a dialysis bag method. Transferring four vincristine sulfate liposome preparations into a dialysis bag after treatment, taking PBS as a release medium, adding 80mmol/L ammonium chloride and 10mmol/L histidine buffer solution, regulating pH value to 7.4 with sodium hydroxide, regulating to isoosmotic with 5% glucose injection, placing in a dissolution cup containing 150mL release medium in the dark, stirring at constant speed of 100rpm at 37+ -1deg.C, respectively sucking 2.0mL dialysis solution at 0.5, 1, 2, 4, 6, 8, 12, 24, 36 and 48 hr, simultaneously supplementing the release medium with the same amount and the same temperature, measuring drug concentration with high performance liquid chromatography, and calculating cumulative release amount R according to the following formula _n 。

Wherein the volume of the release medium is V ₀ Concentration at the nth sampling is C _n The concentration at the n-1 th sampling is C _n-1 The sampling volume is V, and the total medicine amount is M _t 。

The results showed no significant difference in drug release rates (p > 0.05) for the CL (VCR-PCL and VCR-SCL) and SAL (VCR-PSAL and VCR-SSAL) groups for the two drug delivery methods, indicating that the modification of SA-CH did not alter the in vitro release behavior of the drug in the formulation. The significantly reduced drug release rate of VCR-SCL/VCR-SSAL compared to VCR-PCL/VCR-PSAL (< 0.05), indicates that SOS-TEA gradient drug loading effectively delayed VCR release.

EXAMPLE 6 shelf stability investigation of vincristine sulfate Liposome preparation (FIG. 3)

According to the guidelines of drug stability experiments, each VCR liposome preparation was placed at 4±2 ℃ for 0, 1, 2 and 3 months, respectively, for long-term stability experiments. The specific operation is as follows: three batches of VCR-PCL, VCR-PSAL, VCR-SCL and VCR-SSAL liposome preparation were prepared, packaged in brown penicillin bottles, sealed with nitrogen, stored under experimental conditions in a dark place, and sampled at a specified time to determine the particle size and encapsulation efficiency of each sample.

The result shows that the encapsulation rate of the VCR liposome prepared by the pH gradient method is obviously reduced in the three-month examination period, and the VCR liposome prepared by the SOS-TEA gradient method has good placement stability, so that the stability of the VCR liposome can be obviously improved by drug loading by the SOS-TEA gradient method.

EXAMPLE 7 uptake investigation of Liposome formulations by mouse RAW264.7 cells (FIG. 4, FIG. 5)

In order to evaluate that sialic acid modified liposome can effectively increase internalization effect of TAMs on drugs, the mouse mononuclear/macrophage leukemia cell line RAW264.7 is used as an in vitro macrophage model for carrying out uptake condition analysis. Mouse RAW264.7 cells were gently blown into cell suspension with cell culture medium at 1X 10 per well ⁵ Density of cells was inoculated into 6-well plates and placed at 37℃in 5% CO ₂ Culturing in an incubator for 24 hours to allow the cells to adhere to the wall completely. The original culture solution in the wells is discarded, sterile serum-free culture solution containing DiR-labeled sialic acid unmodified or modified liposome (recorded as DiR-CL/DiR-SAL) is replaced, the culture solution is put into an incubator for co-incubation for 2 hours, the liquid in the wells is discarded, 1.0mL of sterile PBS is added into each well for 3 times of washing, cells are digested, centrifugation is carried out at 1200rpm for 4min, the cells are collected, 4% paraformaldehyde is added for fixation and transfer into a flow tube, and the average fluorescence intensity of the sample is detected on a flow cytometer.

To verify whether SA modification can mediate uptake of the formulation by macrophages, a pre-saturation group of SA (denoted DiR-SAL (SA)) was set, i.e., SA solution (final concentration of SA 10.0 mg.mL) was added prior to incubation with the formulation ^-1 ) Incubating with RAW264.7 cells, discarding the liquid in the wells, replacing the sterile serum-free culture solution containing DiR-labeled sialic acid modified liposome (DiR-SAL), incubating for 2h in an incubator, discarding the liquid in the wells, adding 1.0mL of sterile PBS for 3 times into each well, centrifuging at 1200rpm for 4min after cell digestion, collecting cells, adding 4% paraformaldehyde for fixation and transferring to a flow tube, and detecting the average fluorescence intensity of the sample on a flow cytometer.

In addition, to further investigate the effect of sialic acid modification on cellular uptake, confocal laser microscopy was used to observe the uptake of DiR-labeled liposomes by RAW264.7 cells. Taking a 6-hole plate, adding 50 mu L of cell culture solution into each hole, and putting the cell climbing slices into the holes so that the climbing slices are adsorbed at the bottom of the hole plate. Preparing cell suspension, inoculating cells onto a climbing plate, placing the climbing plate in an incubator for incubation for 24 hours, discarding liquid in a hole, adding a sterile serum-free culture solution containing DiR-labeled liposome (DiR-CL/DiR-SAL) for incubation for 2 hours, discarding the liquid in the hole, adding 1.0mL of PBS solution along the wall for cleaning the cells for 3 times, adding 4% paraformaldehyde for fixing the cells, discarding the liquid after 20 minutes, and adding PBS solution for cleaning the cells for 3 times. The nuclear dye DAPI was added and incubated at room temperature in the dark for 30min, and the cells were washed 3 times with PBS solution. And (3) lightly spin-drying the climbing sheet, dripping the anti-fluorescence quenching sealing sheet on a glass slide, taking out the cover glass from the culture plate, buckling the surface with cells attached on the glass slide downwards, removing bubbles, sucking the overflowed sealing sheet, sealing the climbing sheet, and observing and photographing under a laser confocal microscope. A SA pre-saturation group, denoted DiR-SAL (SA), was also set.

Flow cytometry results show that the fluorescence intensity in DiR-SAL group RAW264.7 cells is significantly higher than that in DiR-CL group, about 2.7 times that in DiR-CL group, indicating that SA modification significantly increases the uptake of the preparation by cells. Competitive inhibition experiments show that the pre-saturation treatment of SA solution remarkably inhibits the uptake of DiR-SAL by RAW264.7 cells, and free SA is hypothesized to be combined with Siglec-1 receptors on the cell surface as a competitive inhibitor to block the combination of SA modified liposome and RAW264.7 cell receptors, so that the uptake of cells is remarkably inhibited.

Laser confocal microscopy showed that SA modified liposomes exhibited the highest cellular uptake, and pre-saturation with SA solution could significantly reduce the uptake of DiR-SAL by RAW264.7 cells. The results are consistent with the results of flow cytometry, and indicate that the SA group modified on the surface of the liposome can effectively promote the uptake of the liposome by macrophages, which is important for the medicine to play an in-vivo tumor treatment role.

EXAMPLE 8 in vitro cytotoxicity investigation of vincristine sulfate Liposome preparation on mouse RAW264.7 cells and S180 cells

The in vitro cytotoxicity of each VCR liposome preparation on mouse RAW264.7 cells and S180 cells was determined using the MTT method, and the specific procedure is as follows:

(1) Concentration gradient configuration

VCR-PCL, VCR-PSAL, VCR-SCL, VCR-SSAL and VCR solution (VCR-S) were passed through a 0.22 μm microporous filter membrane in a sterile clean bench and the 5 VCR preparations were diluted to 7 concentration gradients with serum-free cell culture medium for use.

(2) S180 cell buried plate

S180 cells in good growth state were collected and cell suspensions were prepared at 1X 10 per well ⁵ Density of cells was inoculated into 96-well plates, and 200. Mu.L of PBS was added to each well of the edge wells and placed at 37℃in 5% CO to prevent edge effects due to liquid evaporation ₂ Culturing in an incubator.

(3) RAW264.7 cell embedded plate

RAW264.7 cells in good growth state were collected and cell suspensions were prepared at 1X 10 per well ⁵ Density of cells was inoculated into 96-well plates, and 200. Mu.L of PBS was added to each well of the edge wells and placed at 37℃in 5% CO to prevent edge effects due to liquid evaporation ₂ Culturing in an incubator.

(4) Adding medicine and incubating

10 μl of each sterile VCR liposome diluted in serum-free medium was added to each well, and 3 multiplex wells were set for each sample concentration. Furthermore, on each plateZero-setting wells (added culture medium, without cells and preparation), blank wells (added culture medium and equal dose of drug, without cells) and control wells (added culture medium and cells, without drug) were additionally provided. After completion of dosing, the 96-well plate was placed in CO ₂ Culturing in an incubator for 48 hours.

(5) MTT reaction

Under the condition of light shielding, adding newly configured 5 mg.mL into each hole ^-1 MTT solution, 10 mu L per well, was placed in an incubator and incubated for 4h to reduce MTT to purple formazan. 100 μl of sterile triple solution (SDS 10g, isobutanol 5mL,10mM HCl 0.1mL,100 ℃ high pressure steam sterilized for 8 min) was added to each well and allowed to stand overnight at 37 ℃ to allow sufficient dissolution of formazan at the bottom of the well.

After completion of the MTT reaction, the 96-well plate was placed in an enzyme-labeled instrument, the Optical Density (OD) value was measured at a wavelength of 570nm, data was recorded, and the cell viability was calculated as follows:

cell viability (Cell viability,%) = (experimental well OD value-zerowell OD value)/(control well OD value-zerowell OD value) ×100%, and half-inhibitory concentration of cells was calculated (Half inhibitory concentration, IC) ₅₀ ) The results are shown in Table 9.

TABLE 9 half inhibition concentration of vincristine sulfate liposome formulations on RAW264.7 and S180 cells

The results show that each VCR liposome has a certain growth inhibition effect on S180 cells and RAW264.7 cells, and is dose-dependent. SA modification can significantly enhance the inhibition of cells by drug, either pH gradient or SOS-TEA gradient prepared liposomes (< 0.05). The cytostatic effect of vincristine sulfate liposome formulations prepared by SOS-TEA gradient method was significantly reduced compared to pH gradient prepared liposomes (< 0.05), which may be related to slow release of liposomal drug prepared by SOS-TEA gradient method.

Example 9S180 in vivo fluorescence imaging and tissue distribution in tumor-bearing mice (FIG. 6)

The preserved S180 cell freezing tube is taken out from liquid nitrogen and is quickly placed into water at 37 ℃ for resuscitation. Resuscitated S180 cell suspension was inoculated into the abdominal cavity of a kunming mouse. And (3) extracting milky viscous ascites under aseptic conditions after 6-8 days, counting under an inverted microscope, diluting into cell suspension by adding normal saline when the activity of tumor cells is more than 95%, and adjusting dilution times. The S180 cell suspension was inoculated into subcutaneous tissue in the right anterior axilla of mice, 0.2mL each, 6 total, using 75% alcohol sterilization. Each group of mice reached 1000mm in tumor volume ³ After this (about day 10-12 after inoculation), the mice were randomly divided into 2 groups, i.e. the unmodified liposome group and the sialic acid modified liposome group (denoted as DiR-CL and DiR-SAL, respectively), 3 each. 1 mg/kg ^-1 The DiR-labeled liposomes were injected into the tail vein of the dose, in vivo fluorescence imaging was performed at 1, 4, 8 and 24 hours, respectively, and the fluorescence intensities of the tumor tissues of each group of mice were measured. Mice were sacrificed after 24h, tumors were isolated for ex vivo organ imaging with other major organs, and the average fluorescence intensity of each organ was measured.

The result shows that the fluorescence intensity of DiR liposome at the tumor part is gradually enhanced along with the extension of time, and the fluorescence intensity of both groups reaches a peak value at 8 h. DiR-SAL group always has higher fluorescence intensity in tumor tissue after injection compared to DiR-CL group. This is probably due to the fact that SA modified liposomes can enhance uptake of phagocytic systems, such as neutrophils and monocytes, in the blood circulation, and that circulating leukocytes phagocytosed of the nanopreparation carry the drug across the vessel wall into the tumor tissue under the driving of chronic inflammation of the tumor, resulting in more drug retention at the tumor site. After 24h of injection of the preparation, tumors and other major organs were collected and the fluorescence intensity of each tissue was measured. The results show that the fluorescence intensity of DiR-SAL at the tumor site is significantly higher than that of DiR-CL group (< 0.05 p), whereas there is no significant difference between the two formulation groups in other major organs (p > 0.05). In conclusion, SA-modified liposomes are able to target tumors effectively in vivo.

EXAMPLE 10 Wistar rat in vivo pharmacokinetic behavior of vincristine sulfate Liposome formulation (FIG. 7)

15 Wistar rats weighing 180-220 g were randomly divided into 5 groups (n=3), i.e., VCR-S, VCR-PCL, VCR-PSAL, VCR-SCL and VCR-SSAL groups. Intravenous injection of each group of preparations with the dosage of 2 mg.kg ^-1 VCR. Blood samples were collected from the orbital sinus at specific time intervals in heparin-pretreated tubes. Plasma was separated by centrifugation at 5000rpm for 10 min. 200. Mu.L of plasma is taken, added with 800. Mu.L of methanol, mixed evenly, immediately placed in a centrifuge for centrifugation at 5000rpm for 10min, the supernatant is sucked up, and the centrifugation is repeated once. The supernatant was filtered through a 0.22 μm microporous filter, 200. Mu.L of the filtrate was sampled and analyzed by HPLC, the concentration of VCR in each sample was measured, a pharmaceutical time curve was drawn, and relevant pharmacokinetic parameters were calculated, and the results are shown in Table 10.

Table 10 pharmacokinetic parameters of vincristine sulfate liposome formulations

The results show that VCR solution (VCR-S) is completely cleared from blood circulation within 5min, and each VCR liposome significantly reduces the clearance rate of the drug, prolonging the in vivo circulation time of VCR (p < 0.01). The SOS-TEA gradient produced liposomes with longer in vivo circulation times (< 0.05) compared to VCR liposomes produced with pH gradient.

EXAMPLE 11 vincristine sulfate Liposome preparation anti-tumor study on S180 tumor-bearing Kunming mice (FIG. 8, FIG. 9)

The preserved S180 cell freezing tube is taken out from liquid nitrogen and is quickly placed into water at 37 ℃ for resuscitation. Resuscitated S180 cell suspension was inoculated into the abdominal cavity of a kunming mouse. And (3) extracting milky viscous ascites under aseptic conditions after 6-8 days, counting under an inverted microscope, diluting into cell suspension by adding normal saline when the activity of tumor cells is more than 95%, and adjusting dilution times. The S180 cell suspension was inoculated into subcutaneous tissue in the right anterior axilla of mice, 0.2mL each, and 36 total mice were inoculated using 75% alcohol sterilization. On day 4 after tumor bearing, mice were randomly divided into 6 groups of 6 per group, control, VCR-S, VCR-PCL, VCR-PSAL, VCR-SCL, VCR-SSAL. All groups of mice were in swelling Tumor volume reaches 100mm ³ The administration was started after the period (4 days after inoculation), 1 time every 3 days, 5 times (10, 13 and 16 days after inoculation), and each group had a single VCR administration dose of 0.5 mg.kg ^-1 The Control group was given an equal volume of 5% dextrose injection. During the whole pharmacodynamic experiment, data of tumor volume, body mass, death event, etc. were recorded.

The inhibition effect of each VCR preparation on the S180 tumor is sequentially from strong to weak: VCR-SSAL > VCR-PSAL > VCR-SCL > VCR-PCL. Although VCR-S can inhibit tumor growth, the mice in the group have poor overall survival condition, poor overall lean condition, loose bones and aversion to cold, death phenomenon occurs on the 17 th day of tumor bearing, and all the 22 th day of tumor bearing die, which proves that the VCR-S has higher nonspecific toxicity to organisms and the toxic and side effects far exceed the therapeutic effect on tumors. Compared with the VCR-S group, mice in each preparation group have good survival condition and active fur color. It is noted that the tumor inhibiting effect of the VCR-SSAL group is optimal, and can be explained from two aspects, on one hand, the SA-modified liposome has good tumor targeting compared with the VCR-SCL group without the modification of SA. On the other hand, compared with the VCR-PSAL prepared by the pH gradient method, the VCR liposome prepared by the SOS-TEA gradient method has good in-vitro and in-vivo stability, longer in-vivo circulation time, can be slowly released after entering a tumor, and can permanently influence tumor cells and tumor related immune cells, thereby changing tumor immune microenvironment and activating the anti-tumor immune response of an organism.

When the VCR liposome plays an anti-tumor effect, the VCR liposome can damage other normal tissues of the body, and the nonspecific toxicity of the medicine can be rapidly reflected by reasonably evaluating the change of the body mass. During the experiment, the VCR-S group had a large fluctuation of body weight and overall a decreasing trend, indicating that the drug solution had extremely strong toxicity, significantly reducing the quality of life of mice. Compared with the VCR-S group, the weight fluctuation of the other administration groups is smaller, the mice have good survival conditions, and the mice have no death phenomenon. In order to fully compare the effectiveness and targeting of the preparation and give consideration to the inhibition of the preparation on Tumor cells and the non-specific damage to organisms, the laboratory combines Tumor volume and body weight, and provides a new evaluation index of Tumor inhibition index (Tumor inhibition index), namely Tumor-bearing animal mass/Tumor mass (mass Tumor inhibition index) or Tumor-bearing animal volume/Tumor volume (volume Tumor inhibition index), and the larger the Tumor inhibition index is, the better the overall treatment effect is. Since the quality of mice and the quality of tumors are easily obtained, the therapeutic effect of each administration group was comprehensively evaluated using the quality tumor suppression index, and the results are shown in table 11. The results show that the tumor inhibition indexes of VCR-PCL, VCR-PSAL, VCR-SCL and VCR-SSAL are 2.12 times, 4.70 times, 2.92 times and 14.79 times of that of the Control group respectively, and the tumor inhibition indexes of mice in the VCR-S group are smaller than that of the Control group due to the rapid decrease of the weights of the mice in the latter period, so that the toxicity of the VCR-S group on the organism is far beyond the therapeutic effect on tumors. In contrast, each VCR formulation group reduced the toxicity of the free drug, wherein the tumor suppression index of VCR-SSAL group was significantly greater than that of other groups (p < 0.01), indicating that VCR-SSAL not only had better tumor suppression effect, but also had less nonspecific toxicity to the body and the overall therapeutic effect was optimal. The tumor inhibition index organically combines the tumor growth condition and the life quality, amplifies the difference among the groups, more clearly reflects the comprehensive curative effect of the preparation in vivo, and has wider application prospect than the tumor inhibition rate.

Table 11 tumor inhibiting effect of vincristine sulfate liposome formulations

Example 12S180 tumor-bearing Kunming mouse tumor and important tissue sections (FIG. 10)

VCR is a cell non-specific antitumor drug, and can generate certain toxicity to normal cells of other tissues while killing tumor cells, so that after the drug effect experiment is finished, heart, liver, spleen, lung, kidney and tumor tissues of each mouse are collected and used for HE pathological sections.

The results show that (1) a little myocardial damage (at the black arrow) can be observed by the Control group and the VCR-S group, and myocardial fibers of the VCR-PCL, the VCR-PSAL, the VCR-SCL and the VCR-SSAL groups are uniformly colored, the cell demarcation is clear, the shape is consistent, and no obvious abnormality is seen; (2) VCR-S group had significant liver injury, cytochalasing (black arrow), and other groups did not find significant liver injury; (3) The spleens of the Control and VCR-S groups were seen with a small amount of granulocyte infiltration (at black arrows), and the VCR-PCL, VCR-PSAL, VCR-SCL, and VCR-SSAL groups were seen with an increased granulocyte infiltration (at black arrows); (4) No abnormalities in lung and kidney tissues were observed in each group; (5) The Control and VCR-S groups showed a high nuclear allotype and high nuclear mass ratio, and a more pronounced deep staining, indicating that the tumor tissue grew well (black arrows) and only a small tissue necrosis area was present (red arrows). The tissues of the VCR-PCL, VCR-PSAL, VCR-SCL and VCR-SSAL groups are necrotized in large areas, a large number of tumor cell nuclei are deeply stained, disintegrated or dissolved, and are fused with surrounding tissues to form unstructured eosinophils (red arrows) which are pink and rarely have a mitotic phase. Wherein, the powder-dyed area of the VCR-SSAL group is the largest, and the tumor tissue almost entirely necrotizes, which indicates that the VCR-SSAL group has the largest killing degree to the tumor tissue.

Example 13 immunofluorescence analysis of tumor sections (FIG. 11, FIG. 12, FIG. 13)

To examine the effect of each VCR preparation on tumor tissue proliferation, tumor tissues of each group of mice were collected after the end of the antitumor experiment, fixed dehydrated, and frozen into sections. Proliferation of tumor cells, infiltration of M2 type macrophages and cytotoxic T cells after treatment with each VCR preparation was analyzed by selecting proliferating cell associated nuclear antigen Ki-67, pan-macrophage marker (CD 68) and M2 type macrophage marker (CD 163), pan-T cell marker (CD 3) and cytotoxic T cell marker (CD 8) labeled tumor sections, while using DAPI dye staining for nuclear localization. After the anti-fluorescence quenching sealing tablet is sealed, the tumor slice is observed under a fluorescence microscope and photographed.

The results show that the tumor tissue of the Control group shows higher Ki-67 fluorescence signals, has more macrophage infiltration, is mostly of the M2 subtype, and lacks cytotoxic T cell infiltration. Indicating that in the process of tumor growth, the lack of effective anti-tumor immune cell activation, tumor cells gradually "acclimate" surrounding immune cells, so that the surrounding immune cells are converted into an immunosuppressive phenotype, and the immunosuppressive tumor immune microenvironment is shaped, thereby promoting tumor growth. The tumor tissue of each treatment group exhibited a lower Ki-67 fluorescence signal, indicating a reduced proliferation rate of tumor cells. Wherein, the proliferation signal of the tumor tissue is the lowest after VCR-SSAL treatment, the infiltration amount of M2 type macrophages is obviously reduced, and a large amount of cytotoxic T cells infiltrate, which proves that the VCR-SSAL can kill tumor cells and improve the environment of immunosuppression of tumor parts, relieve the immunosuppression induced by the M2 type macrophages and activate the anti-tumor immune response of organisms.

EXAMPLE 14 determination of inflammatory factor levels in tumor tissue

To evaluate whether different VCR formulations are effective in improving the immunosuppressive environment within a tumor, enhancing the anti-tumor immune response, enzyme-linked immunosorbent (Enzyme-linked immunosorbent assay, ELISA) methods were used to investigate the concentration levels of inflammatory factors IL-12, IFN- γ and pro-tumor factors IL-10, TGF- β in tumor tissue supernatants after treatment. After the drug effect is finished, taking each group of tumor tissues, weighing, adding PBS according to the weight-to-volume ratio (1:9), and homogenizing by using a tissue homogenizer. Centrifuging at 10000rpm for 10min after homogenizing, and collecting supernatant. Experiments were performed using the steps described in the ELISA kit instructions to quantify tumor tissue cytokine concentration levels, and the results are shown in Table 12.

TABLE 12 determination of inflammatory factor levels in tumor tissues

The expression level of IFN-gamma and IL-12 in the tumor tissue homogenate of the Control group is lower, and the expression level of inflammatory factors of each treatment group is obviously improved. Notably, the IFN-. Gamma.and IL-12 concentrations in the VCR-SSAL group tumor tissue homogenates were 3.3 and 12.4 times that of the Control group, respectively, and the IFN-. Gamma.and IL-12 concentrations in the VCR-SSAL group tumor tissue homogenates were 1.4 and 1.5 times that of the VCR-PSAL, respectively. The expression level of IL-10 and TGF-beta in the tumor tissue homogenate of the Control group is higher, and the concentration of IL-10 and TGF-beta in the tumor tissue of the mice is obviously reduced after VCR-SSAL treatment. The result shows that the VCR-SSAL treatment can obviously promote the inflammatory factor level of the tumor part, reduce the expression level of the tumor promoting factor of the tumor part, effectively improve the immunosuppressive property of the tumor part, strengthen the anti-tumor immune response of mice and restore the tumor immune monitoring.

Example 15 tumor "shedding" analysis (FIG. 14, FIG. 15)

Surprisingly, during the course of the experiment, the phenomenon of "shedding" of the tumor from the growth site was observed, and the wound gradually healed. Wherein 2 (33.3%) mice in the VCR-SSAL group developed tumor "shedding" during the treatment period, 1 (16.7%) mice in the VCR-PSAL group and the VCR-SCL group developed tumor "shedding" respectively, and the VCR-PCL group did not develop the tumor "shedding". The VCR-SSAL group mice "shed" tumors on days 15, 19, the VCR-PSAL group mice "shed" tumors on day 16, and the VCR-SCL group mice "shed" tumors on day 18. Fig. 14 shows the overall process from tumor "shedding" to wound healing in one mouse: the tumor was shed from the growth site, which showed a deep red hole-like wound with no hair coverage (day 15); after 2 days, the wound healed slowly, the surface appeared light red, and fine hair grew out (day 17); after 4 days, the wound heals further, the wound area becomes smaller, a circle of white crusts with harder texture is formed around the wound, and the hair coverage area becomes larger (day 19); white crusting and shedding around the wound after 6 days, and further shrinking the wound (day 21); after 8 days, the wound healed substantially completely, gradually approaching normal skin, with substantially complete hair coverage (day 23); after 10 days, all the hair grew out from the wound site, which was not different from the normal skin (day 25). After wound healing, mice with "shedding" tumors were observed continuously, with no signs of tumor recurrence within 3 months.

To examine the enhancement effect of each VCR liposome on the antitumor immunity of the organism, after observing for 3 months, the above 4 tumor "shedding" mice were taken, the two tumor-bearing on the contralateral axilla was marked as S group according to the method under "example 17", and 6 healthy mice of the same age were taken to bear the tumor at the same position and marked as Control group. The tumor growth was observed without drug treatment, the tumor length, the tumor diameter, the mouse body mass and the mouse growth were recorded, and the tumor volume, the tumor suppression index and the relative tumor suppression index were calculated and compared with the growth of the 4 mice (designated as group F) after the first tumor loading.

The result shows that the tumor growth of the Control group mice is extremely rapid, the tumor growth curve has obvious 'tail-warping' phenomenon on the 18 th day after tumor loading, which indicates that the immune system of the organism can not effectively inhibit the tumor growth, and the tumor still has the trend of rapid growth. Due to the effect of the medicine, the tumor growth rate of the group F mice is obviously reduced, and along with the continuous accumulation of the medicine, the phenomenon of 'shedding' of the tumor appears from the 15 th day after tumor loading, and the tumor growth rate is obviously slowed down until the 19 th day of tumor is completely 'shed'. Compared with the F group, the tumor growth of the S group mice is slower, 1 mouse (25%) is in tumor "shedding" phenomenon on the 12 th day after tumor loading, and all the 3 mice (75%) on the 14 th day are in tumor "shedding" phenomenon (therefore, the 14 th day tumor volume data are not shown in a tumor growth curve chart) and the time for the F group mice to have tumor "shedding" is earlier than that of the F group mice.

The relative tumor inhibition index of the F group is slightly higher than that of the S group on the 4 th to 8 th days after tumor bearing, but no significant difference exists. From day 10, the relative tumor suppression index of group S gradually increased, significantly higher than that of group F. On day 12 post-tumor bearing, the relative tumor suppression index for group S reached 3.1 times that for group F. The tumor suppression index of Conrol group is continuously and rapidly reduced, and the tumor suppression index of S group is slightly reduced but has smaller change range. On day 12 after tumor bearing, the tumor suppression index of group S reached 13.3 times that of the Control group. It follows that the tumor "sloughed" and healed mice had a stronger anti-tumor immune response to S180 tumor cells than the same age healthy mice.

The cause of tumor "shedding" was analyzed: (1) The SOS-TEA gradient drug-loaded preparation has more stable in vivo and in vitro stability, so that the tumors of the mice in the VCR-SCL group are "shed" while the tumors of the mice in the VCR-PCL group are not "shed", 2 mice in the VCR-SSAL group are "shed" and 1 mouse in the VCR-PSAL group are "shed". (2) SA modified liposome can improve the uptake of phagocytic systems such as neutrophils and monocytes in blood circulation, and the circulating leukocytes phagocytosing the nano-preparation are driven by the chronic inflammation of the tumor to carry the drug to enter the tumor tissue through the vascular wall, so that more drug is retained at the tumor site. And then the preparation releases VCR to kill tumor-related immune cells and tumor cells such as TAMs, and induces DNA damage in various modes, so that the quantity of the tumor-related immune cells and tumor cells such as the TAMs is reduced, simultaneously releases DNA damage signals, activates the adaptive immunity of the organism, recruits adaptive immune cells such as cytotoxic T cells and the like to infiltrate into tumor parts. Meanwhile, various cytokines (such as TGF-beta, IL-10 and the like) with immunosuppressive effects secreted by TAMs and tumor cells start to decrease, so that the infiltration amount of tumor-related immune cells for maintaining the immunosuppressive characteristics of tumor immune microenvironment gradually decreases, the integrity of the tumor immune microenvironment is destroyed, and more preparations can enter the tumor to play a role. Under the dual actions of the medicine and the immune system, the tumor microenvironment for maintaining the growth of the tumor is gradually disrupted, so that the tumor is cleared as a foreign body by the immune system of the organism, and the phenomenon of tumor shedding appears.

The S180 tumor cells are charged again in the body of the mice after healing, and under the condition that no drug treatment is given, the phenomenon of secondary tumor 'shedding' appears, which is possibly beneficial to the activation of VCR preparation to the whole organism immune environment after the first tumor charging, promotes the organism immune cells to recognize the S180 tumor antigen and generate immune memory. When S180 cells invade the organism again, the adaptive immune response of the organism can be activated rapidly, so that the tumor cells can not recruit a large amount of immunosuppressive tumor-related immune cells to help the development of the tumor cells, the tumor cells in 'army struggle' are in a weak condition in 'fight' with the immune cells, and are cleared by the organism, and the phenomenon of 'shedding' of secondary tumors occurs. In addition, there was no significant difference in survival and quality of life of 4 mice in which tumor shedding occurred during the 3-month observation period at the end of one tumor-bearing course. The phenomenon of tumor 'shedding' in a secondary tumor-bearing experiment shows that a VCR (complementary deoxyribonucleic acid) possibly has strong immune activation and remodeling potential, but is limited by the problems that the traditional preparation is poor in targeting and cannot effectively act on tumor-related immune cell groups, and the like, so that the curative effect of the VCR is difficult to be exerted, and the SA modified liposome can effectively act on a platform of the tumor immune cell groups for targeted delivery, so that a new world can be developed for a series of traditional chemotherapy drugs such as the VCR.

By combining the experimental results, a conclusion can be drawn that: the gradient liposome modified by sialic acid prepared by the sucrose octasulfate triethylamine gradient method is used as a carrier, and the further prepared vincristine sulfate liposome preparation has the significance of improving the preparation stability, endowing the preparation with tumor active targeting capability and enhancing the anti-tumor immune response of organisms. In addition, the invention is to be noted that the tumor immune microenvironment is changed by double influences on tumor cells and tumor-related immune cells based on the carrier targeting tumor-related immune cells such as tumor-related macrophages, so that the anti-tumor immune response of the organism is recovered, the drug and the immune system of the organism play a synergistic effect to inhibit the growth of tumor and even remove tumor, and a new thought is provided for the application of clinical anti-tumor chemotherapy drugs.

Claims (10)

1. The sialic acid modified gradient liposome is characterized in that sphingomyelin and cholesterol are used as liposome membrane materials, sialic acid-cholesterol conjugate is used as a targeting group, and SOS-TEA solution is used as a hydration medium solution.

2. The sialic acid modified gradient liposome of claim 1, wherein the sphingomyelin: cholesterol: sialic acid-cholesterol conjugate= (50-60): (35-45): (2-10); according to the mass ratio, sphingomyelin: SOS-TEA= (1-5) in hydration medium solution: 8.

3. A vincristine sulfate liposome preparation, characterized in that vincristine sulfate is used as a drug, and the sialic acid modified gradient liposome of claim 1 or 2 is used as a carrier; wherein, according to the mass ratio of the medicine to the fat, vincristine sulfate: sphingomyelin = 1 in sialic acid modified gradient liposomes: (5-20).

4. The vincristine sulfate liposome preparation according to claim 3, wherein the encapsulation efficiency of the vincristine sulfate liposome preparation is more than 95%, the particle size is 100-110 nm, the polydispersity is 0.01-0.04, and the zeta potential is-20 to-30 mV.

5. The method for preparing sialic acid modified gradient liposome of claim 1 or 2, wherein the sucrose octasulfate triethylamine gradient method is adopted.

6. The method for preparing sialic acid modified gradient liposomes of claim 5, comprising the steps of:

(1) Preparing hydration medium solution

Weighing sucrose octasulfate, and adding distilled water for dissolution to obtain sucrose octasulfate solution; passing through a strong acid hydrogen type cation exchange resin column to convert sucrose octasulfate into free acid to obtain SOS solution;

Regulating the pH value of the SOS solution to 6.0+/-0.5 by using triethylamine, fixing the volume, uniformly mixing, and sterilizing by using a filtering membrane to obtain the SOS-TEA solution, namely a hydration medium solution; wherein, in the SOS-TEA solution, the molar concentration of SOS-TEA is 50 mmol/L-250 mmol/L;

(2) Preparation of blank liposomes

Weighing liposome membrane materials and targeting groups, adding absolute ethyl alcohol, and stirring and dissolving completely at 60-80 ℃ to obtain membrane material solution; continuously stirring, volatilizing absolute ethanol to obtain membrane material concentrated solution; the liposome membrane material is sphingomyelin and cholesterol, and the targeting group is sialic acid-cholesterol conjugate; sphingomyelin in molar ratio: cholesterol: sialic acid-cholesterol conjugate= (50-60): (35-45): (2-10);

preheating a hydration medium solution to the same temperature as the membrane material concentrated solution, then mixing the hydration medium solution and the membrane material concentrated solution, and stirring at 60-80 ℃ to obtain a blank liposome primary product; SOS-TEA in hydration medium solution according to mass ratio: sphingomyelin in membrane concentrate = 8: (1-5);

extruding the blank liposome primary product through polycarbonate membranes with different pore diameters at 60-80 ℃ to obtain blank liposome suspension;

(3) Preparation of gradient liposomes

And (3) removing the outer aqueous phase hydration medium solution from the blank liposome suspension, and establishing a liposome transmembrane ion gradient to obtain sialic acid modified gradient liposome.

7. The method of preparing sialic acid modified gradient liposome of claim 6, wherein in step (1), the strong acid hydrogen type cation exchange resin column is 732 type hydrogen cation exchange resin column;

and/or, in the step (2), the concentration of the catalyst is 5-10 mL.min ^-1 Adding the hydration medium solution into the membrane material concentrated solution;

the liposome is extruded, the extrusion pressure is 100 kPa-500 kPa, the aperture of polycarbonate membranes with different apertures adopted in extrusion is 80 nm-400 nm, each aperture passes through 5-10 times, and the apertures pass through from large to small.

8. The method of claim 6, wherein in step (3), the method of creating a liposome transmembrane ion gradient is any one or more of ion exchange, dialysis, and gel filtration to remove aqueous medium solution in the aqueous phase of the liposome.

9. A method for preparing a vincristine sulfate liposome preparation as claimed in claim 3 or 4, characterized by comprising the steps of:

Mixing sialic acid modified gradient liposome and vincristine sulfate medicine solution, incubating medicine carrying at 55-80 ℃ for 10-60 min, and stopping medicine carrying in ice water bath to obtain vincristine sulfate liposome preparation; wherein, according to the mass ratio, vincristine sulfate medicine: sphingomyelin = 1 in sialic acid modified gradient liposomes: (5-20).

10. Use of vincristine sulfate liposome preparation of claim 3 or 4 for preparing antitumor drugs.