CN113293137A

CN113293137A - Modification method of dendritic cells based on cell membrane surface modification technology and application thereof

Info

Publication number: CN113293137A
Application number: CN202010107008.3A
Authority: CN
Inventors: 陈红; 王蕾; 郁李胤
Original assignee: Bmd Biotechnology Suzhou Co ltd
Current assignee: Bmd Biotechnology Suzhou Co ltd
Priority date: 2020-02-21
Filing date: 2020-02-21
Publication date: 2021-08-24
Anticipated expiration: 2040-02-21
Also published as: CN113293137B

Abstract

The invention discloses a modification method of dendritic cells based on a cell membrane surface modification technology and application thereof. The method for modifying dendritic cells based on the cell membrane surface modification technology comprises the following steps: 1) synthesizing a substrate for photothermal transfection; 2) coating a plasmid containing a gene sequence encoding HTP with PEI and placing said plasmid on the surface of said substrate; 3) preparing a modified dendritic cell; 4) synthesizing functional glycomer molecules; 5) mixing and incubating the functional glycomer molecule and the modified dendritic cell. The modification method of the dendritic cells based on the cell membrane surface modification technology can efficiently modify the glycomer with the specific recognition function on the surface of the DC cells, thereby improving the interaction between the DC and the T cells, finally improving the activation efficiency of the T cells, and simultaneously improving the cell transfection efficiency, the activity of the transfected cells and the overall safety of a transfection system.

Description

Modification method of dendritic cells based on cell membrane surface modification technology and application thereof

Technical Field

The invention relates to the fields of molecular biology and vaccines, in particular to a modification method of dendritic cells based on a cell membrane surface modification technology and application thereof.

Background

Immunotherapeutic strategies offer new ideas and directions of development for the prevention and treatment of tumors, and are considered to be the most promising tumor therapeutic strategies. Current strategies for tumor therapy mainly include: cancer vaccines, adoptive immunotherapy such as CAR-T (Chimeric Antigen Receptor T-Cell), and immune checkpoint blockers. Among the above strategies, cancer vaccines can overcome the toxic and side effects of adoptive immunotherapy and immune checkpoint blockers due to the activation of the regulatory function of the human autoimmune system, and are considered to be the most promising tumor treatment strategy.

Strategies to target dendritic cells, T cells, macrophages, and bone marrow derived immunosuppressive cells are widely used in cancer vaccines. Among them, the Dendritic Cell (DC) vaccine has the ability to regulate the autoimmune system in vivo, and is considered as the most safe and effective vaccine strategy. After surgical resection, chemotherapy and other treatments, a large amount of tumor antigens are generated in situ, DCs phagocytose the antigens and present the antigen information to T cells in the form of Major Histocompatibility Complex (MHC), the T cells start activating their activation process after receiving the first signal of MHC, and then co-stimulatory molecules CD80, CD40, etc. on the DC surface bind to T cell surface receptors (TCR) to further activate the proliferation and differentiation of T cells. In the process of interaction between DC and T cells, cytokines such as Interleukin-2 (Interleukin-2, IL-2) and Interferon-gamma (Interferon-gamma, IFN-gamma) secreted by DC and T cells further promote the differentiation and maturation of T cells. Therefore, the T cell activation efficiency of the DC can be effectively improved by enhancing the interaction between the DC and the T cell. This is an effective means to improve the efficiency of DC vaccines. Prior art studies on DC vaccines include:

patent document 1(CN102787097B) uses a viral vector to transfect DC with SYK gene, and modifies the DC, which can be used for preparation of DC vaccines. This patent document describes the use of lentiviruses to perform SYK gene transfection of DCs, allowing them to efficiently express co-stimulatory molecules that promote T cell activation. However, this method is not efficient for transfection. The transfected cells need to be accessible for use by further screening and culture methods, and the method is long in period, high in cost and not beneficial to practical use. The reason for this may be that virus-transfected cells are somewhat tolerant, resulting in some loss of expression during cellular metabolism. Thereby affecting the final expression. Patent document 2(CN107286247B) discloses a chimeric antigen receptor and its gene and recombinant expression vector, an engineered mesothelin-targeted dendritic cell (mesoCAR-DC), and its use. The method disclosed in this patent expresses a DC cell of a chimeric antigen receptor, and the modification method of gene recombination has high requirements on the structural sequence and arrangement sequence of genes. The dendritic cells constructed by the method are only dendritic cells which can target mesothelin, and have single functions and no wide applicability. Patent document 3(CN100548377C) discloses a recombinant adenovirus carrying a gene encoding EB virus latent membrane protein 2, an antigen-presenting cell transduced or modified by the recombinant adenovirus, and a vaccine composition containing the transduced or modified antigen-presenting cell. The method disclosed in this patent loads the DC cells with adenovirus vectors carrying EB virus. The method has the following defects: firstly, the adenovirus used in this method has a risk of transfection, and the transfection efficiency can only reach around 50%. Secondly, the DC cells obtained by the transfection method only can be aligned to EB virus and have no universal applicability. Patent document 4(CN102181407B) discloses a recombinant adenovirus, a dendritic cell modified by the recombinant adenovirus, and applications of the recombinant adenovirus and the dendritic cell; the invention provides a recombinant adenovirus containing a specific protein expression sequence, which is used for infecting dendritic cells to obtain recombinant cells. The recombinant cell and the recombinant adenovirus can be used for preparing a vaccine for preventing and/or treating cervical cancer. The method adopts the recombinant adenovirus to infect the cells, firstly, the cost for preparing the recombinant adenovirus is high, secondly, the cost for transfecting by using the virus is high, and the transfection efficiency is relatively low.

Fusion of antigen and DC in vitro, stimulating maturation of DCs and their reinfusion back into patients was the first strategy used [ J immunity 34,382-389(2011) ]. However, the tumor microenvironment in vivo is complex and the interaction of the purely activated DCs with T cells is significantly restricted. This strategy, even if the DC is simply matured, can increase the efficiency of T cell activation in vitro, and is of little efficacy. To further enhance the interaction effect between DC and T cells, it is the most common method to enhance the activation signal of T cells by transfecting DC by genetic engineering technology so that the DC can efficiently express costimulatory molecules that are favorable for antigen presentation [ Cancer Immunol Immunother 64,831-842(2015) ]. However, there are two major problems with this type of approach: 1. the vaccines have high sample variability, and the activation signal of T cells firstly needs mutual recognition of T cells and DC cells, and secondly can induce the chain reaction of costimulatory molecules. However, the recognition between DC and T cells is weak, which results in failure to function to modify the enhanced signal; 2. there are serious safety hazards in utilizing virus transfection, the introduction of exogenous genetic materials may cause unpredictable gene mutation risks, and the virus transfection cycle is long and high in cost, which is not beneficial to practical applications [ Genes,65,8(2017) ]. Although the electroporation method can avoid the safety problem caused by virus transfection, the electroporation method is very inefficient, and the electroporation method can cause serious damage to cells and has a low cell survival rate [ Cellular and Molecular biology, 4, 538-. Patent document 5(CN104906567B) discloses a ligand-modified nano-preparation in which a tumor antigen peptide or a complex of a tumor antigen peptide and a heat shock protein is encapsulated for activating the antigen presenting ability of DC to T cells. The method adopts nano particles as a carrier and utilizes a DC cell endocytosis method to transfer functional plasmids into the carrier. This approach can only enhance the maturation efficiency of DCs and does not help to improve DC-T cell interactions. Thus, the efficiency of T cell activation elicited by this method is extremely limited. And the gold nanoparticles are ingested without an effective metabolic degradation path, and certain damage can be caused to DC cells.

In the human immune system, T cells are the ultimate effector cells with tumor-specific killing functions after activation by Dendritic Cells (DCs). Therefore, the use of dendritic cells as vaccines to activate the tumor immune activity of T cells is an effective strategy for treating tumors. Activation of T cells is dependent on the antigen presenting ability of DCs. In the process of antigen presentation, first MHC signaling molecules on the DC surface bind to T cell receptors. Co-stimulatory molecules on the DC surface then bind to corresponding receptors on the T cell surface to promote T cell activation. To increase the efficiency of activation, it is an effective strategy to make DCs efficiently express co-stimulatory molecules that aid in antigen presentation.

At present, the most common approach is to transfer a plasmid capable of efficiently expressing co-stimulatory molecules into DCs by gene transfection techniques. However, this strategy has the following problems. First, most of the transfection methods used at present rely on viruses, which may result in unpredictable risk of gene mutation, and the long period and high cost of viral transfection are not suitable for practical application. Although the electroporation method can avoid these problems, the electroporation efficiency is very unstable and large-scale cell death occurs. The expression of cell membrane surface receptors and ligands can be easily controlled by chemical modification, but a large amount of polymerization reaction is required on the cell surface, which causes severe cytotoxicity and cannot maintain long-term modification effect. Secondly, the process of presenting antigen to T cells by DC requires first the binding of MHC molecules of the DC to T cell receptors to initiate the costimulatory pathway, and this binding is weak in the initial stages of DC and T cell action, and the above strategy ignores this problem. For DC and T cells that are not in contact, simply increasing the second signal in the absence of the first signal does not increase the efficiency of antigen presentation by the DC to the T cells. Thus, the premise that DC antigen presentation efficiency can be improved by modifying the ability of DCs to enhance the interaction between DC and T cells.

Many activated groups, such as amino, biotin, etc., are present on the surface of the cell membrane, and thus modification strategies can be designed by the groups on the surface of the cell membrane. Modification strategies such as DNA hybridization, liposome-aptamers, liposome-peptides, biotin-avidin, sugars and lectins [ AngewChemIntEd Engl53,5112-5116(2014) ] have been developed. Among them, the sugar and lectin strategies possess stability and high biocompatibility, and have been widely used for modification of cell membrane surfaces. Modifying sugar molecules to the surface of cell membranes by a phospholipid membrane insertion method is a very mature means at present. However, the membrane insertion method makes the retention time of the modified functional molecules on the cell membrane extremely short, and the modified functional molecules can only be maintained for several hours, and the biological function of the modified cells cannot be maintained for a long time in the practical application process. Therefore, it is required to develop a method capable of maintaining the modification function for a long time.

The above problems can be effectively solved by using Halotag Transmembrane Protein (HTP) as the anchoring functional group on the cell membrane surface [ ACS Biomate. Sci. Eng.4,11, 3658-. The method can solve the problem of the retention of the modified functional molecules on the surface of the cell membrane, and the modification mode does not need to carry out polymerization reaction in a cell solution, thereby greatly reducing the cytotoxicity to the modified cells. The HTP modification technique requires HTP plasmid transfection of cells first, and again faces the technical difficulties of transfection.

In the human immune system, T cells are the ultimate effector cells with tumor-specific killing functions after activation by Dendritic Cells (DCs). Therefore, the use of dendritic cells as vaccines to activate the tumor immune activity of T cells is an effective strategy for treating tumors. Activation of T cells is dependent on the antigen presenting ability of DCs. In the process of antigen presentation, first MHC signaling molecules on the DC surface bind to T cell receptors. Co-stimulatory molecules on the DC surface then bind to corresponding receptors on the T cell surface to promote T cell activation. To increase the efficiency of activation, it is an effective strategy to make DCs efficiently express co-stimulatory molecules that aid in antigen presentation. The DC modification strategy adopted by the invention has wider universality.

Disclosure of Invention

Problems to be solved by the invention

Aiming at the problems in the prior art, the invention hopes to modify the surface of a DC cell membrane by a chemical synthesis method so as to enhance the interaction between DC and T cells and further improve the activation efficiency of DC on T cells.

Means for solving the problems

The invention adopts a gene transfection method of photo-induced perforation, can effectively overcome the safety problem caused by virus transfection, and has high efficiency, high speed and low cost. The invention develops a method for modifying DC by utilizing the photo-thermal transfection system: the method comprises the steps of firstly transfecting the DC with HTP functional plasmids through photothermal transfection, enabling the surface of the DC to have chloralkane receptor groups, meanwhile, carrying out chloralkane modification on functional molecules for modifying the DC, and then anchoring the modified functional molecules to the surface of a DC cell through simple incubation. The method can effectively solve the problems of weak interaction and weak recognition capability of DC and T cells, and the DC modification method used by the invention is safe, efficient and low in cost, and can obtain a large amount of modified DC in a short time.

The DC modification method adopted by the invention is as follows: halotag protein (HTP) is transfected into DC by a photothermal transfection method to form HTP-DC with anchoring functional groups. Meanwhile, a chain transfer agent containing HTP ligand is synthesized, and functional molecules are polymerized by taking the chain transfer agent as a framework to form a modified polymer. Finally, DC modification can be completed through simple incubation. Specifically, the DC modification method provided by the present invention is as follows:

first, a substrate that can be used for photothermal transfection was synthesized. Polydimethylsiloxane (PDMS) with good biocompatibility is selected as a transfection substrate, and Multi-walled Carbon Nanotube (MCNT) is doped into the PDMS by utilizing the photothermal effect of the MCNT. Specifically, PDMS and a cross-linking agent are mixed, MCNT is added, and the mixture is heated and cured to form a film, so that the base material for photothermal transfection can be prepared. The vacuum pumping operation can be simultaneously carried out in the heating process, so that bubbles can be better eliminated.

Subsequently, the prepared substrate was sterilized at high temperature and high pressure, and placed in a cell culture plate to be dried. Coating plasmids containing HTP genes (the plasmids are purchased from Suzhou technology, Inc. of Jinwei Zhi) by using small molecular Polyetherimide (PEI), inoculating DC cells on the surface of a substrate according to a certain density after the plasmids are stably adsorbed on the surface of the substrate, adding PEI coated plasmids containing the HTP genes into the solution again after the cells are attached to the wall, and carrying out transfection under laser with specific power. After transfection is finished, transfected cells are harvested after the cells are continuously cultured for 48 hours, and immunofluorescence staining and RT-PCR methods can be adopted to verify transfection efficiency, and CCK-8 detection can be adopted to verify cell activity.

Meanwhile, anhydrous Tetrahydrofuran (THF), anhydrous N, N-Dimethylformamide (DMF), sodium hydride (NaH) and 6-chloro-1-iodohexane (6-chloro-1-iodohexane) are used as raw materials for reaction, and deprotection is carried out after separation and purification, so as to synthesize an intermediate product C:

then, taking a Chain Transfer Agent (CTA), N-hydroxysuccinimide (NHS) and Dicyclohexylcarbodiimide (DCC) as raw materials, tracking synthesis of NHS-RAFT by using a TLC point plate, adding the deprotected intermediate product C in situ after the raw material point disappears for reaction, and purifying by a silica gel column to obtain a Chain transfer agent A with a chlorinated alkane ligand:

subsequently, referring to a method for synthesizing a double bond-containing sugar molecule monomer in patent No. cn201510203532.x, a sugar molecule monomer having a double bond is synthesized, and a desired modified glycan molecule is obtained by polymerization using the chain transfer agent a obtained by the above synthesis.

And finally, mixing the modified DC and the modified glycan molecules according to a certain concentration, and performing co-incubation on the cells under the conventional culture condition to obtain the glycomer molecule modified functional DC.

The first aspect of the invention provides a method for modifying dendritic cells based on a cell membrane surface modification technology, which comprises the following steps:

1) synthesizing a substrate for photothermal transfection;

2) coating a plasmid containing a gene sequence encoding a Halotag protein (HTP) with a Polyetherimide (PEI) and placing the plasmid on the surface of the substrate in step 1);

3) preparing a modified dendritic cell;

4) synthesizing functional glycomer molecules;

5) mixing the functional glycomer molecules in the step 4) and the modified dendritic cells in the step 3) and incubating to obtain the dendritic cells modified by the functional glycomer molecules.

Wherein the preparation method of the base material in the step 1) comprises the following steps:

mixing the flexible substrate and the crosslinking agent in a ratio of 50: uniformly mixing according to the mass ratio of 1-5: 1, adding 0.5-10 per mill of nano particles of a flexible base material, uniformly mixing again, and heating and curing to form a film, thereby obtaining the base material for photothermal transfection;

preferably, the mass ratio of the flexible substrate to the cross-linking agent is 10:1, adding 10 per mill of nano particles of a flexible base material, wherein the nano particles are more than one of the group consisting of multi-walled carbon nano tubes (MCNT), graphene, gold nano particles and polydopamine nano particles, and the flexible base material is more than one of the group consisting of thermosetting plastics and hydrogel; more preferably, the nanoparticles are multi-walled carbon nanotubes (MCNTs) and the flexible substrate is Polydimethylsiloxane (PDMS).

The concentration of the plasmid in the step 2) is 0.5-2 mu g/10⁴A cell, andthe plasmid is placed on the surface of the substrate in the step 1) for 1-3 hours; preferably, the concentration of the plasmid is 1.5. mu.g/10⁴And (4) cells.

The specific operation of the step 3) is as follows: inoculating dendritic cells on the surface of the substrate containing the plasmids in the step 2), adding PEI again after the dendritic cells are attached to the wall, transfecting under laser, and continuously culturing the cells for 36-60 h, wherein the PEI coats the plasmids containing the gene sequences for coding HTP;

wherein the dendritic cells are seeded at a density of 10⁴～10⁵Per cm²The laser intensity is 1-10W/cm²The irradiation time of the laser is 5-60 s; preferably, the dendritic cells are seeded at a density of 5X 10⁴Per cm²The laser intensity is 1-4W/cm²The irradiation time of the laser is 20-60 s; more preferably, the laser intensity is 2W/cm²The irradiation time of the laser was 30 seconds.

The preparation method of the functional glycomer molecule in the step 4) comprises the following steps:

(i) synthesizing an intermediate product: reacting 2- (2-Boc-aminoethoxy) ethanol, anhydrous Tetrahydrofuran (THF), anhydrous N, N-Dimethylformamide (DMF), sodium hydride (NaH) and 6-chloro-1-iodohexane (6-chloro-1-iodohexane) serving as raw materials, separating and purifying, and then deprotecting to synthesize an intermediate product;

(ii) synthesis of chain transfer agent containing chloroalkane structure: dissolving a chain transfer agent, NHS and DCC in anhydrous DMF, reacting for 10-15 h at 28-32 ℃, adding the intermediate product synthesized in the step (i) in situ after the raw material point of the chain transfer agent in a reaction system disappears, reacting overnight at 25-35 ℃, washing, concentrating and purifying the solution obtained after the reaction to obtain the chain transfer agent containing a chloralkane structure;

(iii) placing the chain transfer agent containing the chloralkane structure, the sugar monomer and the initiator in the step (ii) at 60-80 ℃ for reaction for 10-12 h for polymerization reaction, transferring the reaction solution into a dialysis bag with the molecular weight cutoff of 3500Da for dialysis after the reaction is finished, and freeze-drying to obtain a functional sugar polymer;

preferably, the chain transfer agent is one or more selected from the group consisting of aliphatic mercaptans, dodecyl mercaptan, water, ethers, acids, esters and quinone carbon dioxide, oxygen, alcohols and organic acids; the sugar monomer is selected from more than one of the group consisting of double bond modified mannose (amine), glucose (amine), galactose (amine), fructose (amine), arabinose (amine), ribose (amine), xylose (amine), lyxose (amine) and glyceraldehyde; the initiator is an azo initiator;

more preferably, the chain transfer agent is 4-cyanovaleric acid dithiobenzoic acid (CPADB); the sugar monomer is N-methacryloyl mannosamine (MAM); the initiator is Azobisisobutyronitrile (AIBN).

For ease of detection, biotin monomer is added to the polymerization reaction in (iii).

In a second aspect, the invention provides a dendritic cell produced by the method provided in the first aspect of the invention.

In a third aspect, the invention provides a vaccine composition comprising a dendritic cell according to the second aspect of the invention and one or more pharmaceutically acceptable carriers, adjuvants and/or excipients.

In a fourth aspect, the invention provides a use of the dendritic cell of the third aspect in the preparation of a medicament for the treatment and prevention of malignant tumors. Wherein the malignant tumor is any one of lung cancer, liver cancer, colon cancer, melanoma, prostate cancer, stomach cancer, breast cancer, Chronic Lymphocytic Leukemia (CLL) or chronic myelocytic leukemia; preferably, the malignant tumor is colon cancer.

ADVANTAGEOUS EFFECTS OF INVENTION

The DC cell modification technology combining gene transfection and chemical modification disclosed by the invention can efficiently modify the glycomer with a specific recognition function on the surface of the DC cell, thereby improving the interaction between the DC and the T cell and finally improving the activation efficiency of the T cell. The method combines the gene transfection technology of photoinduced perforation, avoids the defects of virus transfection and electroporation technology to DC, and improves the transfection efficiency, the activity of transfected cells and the overall safety of a transfection system. Specifically, the technical scheme of the invention has the following beneficial effects compared with the prior art:

(1) the photothermal transfection system adopted by the invention has higher universality. The photothermal transfection system can transfect a large number of cells in a short time, and can transfect 10 cells in 10min⁷Individual cells, and the efficiency of viral transfection was not yet observable at the same time.

(2) The raw materials required for synthesis are chemical reagents and base materials commonly used in laboratories, and the transfection base material can be repeatedly used, namely transfection 10⁷The cost of the substrate required for each cell is lower, about 1/5 which is the cost of viral transfection under the same conditions.

(3) The photothermal transfection method adopted by the invention can effectively improve the transfection efficiency of the DC cells. Compared with the virus transfection method, the photothermal transfection efficiency can reach more than 95% in a short time under the same transfection time condition, and the virus transfection efficiency is only less than 10%. Moreover, the photothermal transfection system has a higher safety factor. In addition, photothermal transfection has less effect on cell activity than viral transfection, with a decrease in cell activity of photothermal transfection of around 20% and a decrease in viral transfection of about 30%.

(4) The activity of the T cells is detected through the co-incubation of the DC and the T cells, and the influence of the strategy of modifying the DC adopted by the invention on the induction of the immunological activity of the T cells is verified. As a result, it was found that: the modified DC adopted by the invention can obviously promote the proliferation of T cells, and is about 2.5 times of that of the unmodified DC. Compared with the virus transfection method, the method improves the proliferation efficiency of the T cells by about 1.5 times.

(5) The induction efficiency of the DC modified by the invention on the T cell differentiation is verified by detecting the expression of T cell activating factors TNF-alpha and IFN-gamma. The results show that: the modification method adopted by the invention has the advantages that the expression rates of induced T cell TNF-alpha and IFN-gamma are about 10 times and 8 times of that of unmodified DC; the expression rates of TNF-alpha and IFN-gamma in the virus modification induction method are only improved by about 3-4 times compared with that of the unmodified DC.

(6) And co-incubating the T cells and the tumor cells, and detecting the killing effect of the T cells on the tumor. The results show that: the apoptosis rate of the T cell tumor induced by the modified DC reaches more than 95 percent; the rate of T cell tumor apoptosis induced by unmodified DC is only about 45%. The apoptosis rate of T cell tumor induced by virus transfection modified DC is about 60%. The results show that the modified DC cells adopted by the invention can induce T cells to generate stronger tumor killing capability.

(7) The DC cell modification method adopted by the invention has higher universality and can be suitable for the treatment of various malignant tumors, because the modified functional molecules can improve the induction efficiency of DC on T cell immune activation and cannot influence the specificity of presenting antigen from DC to T cell, the method comprises the following steps: lung cancer, liver cancer, colon cancer, melanoma, prostate cancer, stomach cancer, breast cancer, chronic lymphocytic leukemia and chronic myelocytic leukemia. The invention in a specific embodiment performs functional verification on colon cancer cells.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail as follows:

drawings

FIG. 1 shows a graph of photothermal intensity over time for photothermal transfection substrates under different power irradiation.

Figure 2 shows optimization of DC transfection conditions. Wherein, A in FIG. 2 shows the effect of different plasmid concentrations on transfection efficiency; b in FIG. 2 shows the effect of different laser intensities on transfection efficiency; c in fig. 2 shows the effect of different laser intensities on the activity of transfected cells; the effect of different irradiation times on transfection efficiency is shown in figure 2D.

FIG. 3 shows a comparison of transfection efficiency and cell activity for different transfection methods. Wherein, A in FIG. 3 shows the transfection efficiency of viral transfection and photothermal transfection; b in FIG. 3 shows the effect of different transfection methods on cell activity; c in fig. 3 shows DAPI and FITC staining results for different transfection methods.

Figure 4 shows the molecular structure of polymannan containing chloroalkane ligands.

Fig. 5 shows fluorescence characterization of modified dendritic cells.

Fig. 6 shows the proliferative activity of T cells induced by different DC vaccines. Wherein, a in fig. 6 shows the effect of different DC induction patterns on T cell proliferation rate; b in FIG. 6 shows the effect of different DC induction patterns on the amount of TNF-. alpha.expression; the effect of different DC induction patterns on IFN- γ expression is shown in FIG. 6C.

Fig. 7 shows the tumor toxicity of different kinds of DC vaccines against the colon cancer cell CT 26. Wherein, A in FIG. 7 shows the effect of different DC vaccines on the growth of tumor cells after the DC vaccine acts on the colon cancer cell CT 26; the effect on tumor cell viability after different kinds of DC vaccines were applied to the colon cancer cell CT26 is shown in B of fig. 7.

Detailed Description

The embodiments of the present invention are described as examples of the present invention, and the present invention is not limited to the embodiments described below. Any equivalent modifications and substitutions to the embodiments described below are within the scope of the present invention for those skilled in the art. Accordingly, equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered by the present invention.

The test materials, test reagents and instruments used in the examples of the present invention are commercially available, and the specific information thereof is shown in table 1 below:

table 1: commercial information on test materials and test reagents

Name of reagent	Product shopping information
		4-Cyanovaleric acid dithiobenzoic acid (CPADB)	Sigma Aldrich trade, Inc
2- (2-BOC-aminoethoxy) ethanol	Sigma Aldrich trade, Inc
		N-hydroxysuccinimide (NHS)	Shanghai TCI
sodium hydride	Shanghai TCI
		Dicyclohexylcarbodiimide (DCC)	Shanghai TCI
Anhydrous Tetrahydrofuran (THF)	Shanghai TCI
		Azobisisobutyronitrile (AIBN)	SINOPHARM CHEMICAL REAGENT Co.,Ltd.
Anhydrous N, N-Dimethylformamide (DMF)	Aladdin technologies Ltd
		Recombinant HTP plasmid	Suzhou Jinwei Zhi science and technology biology Ltd
6-diamidino-2-phenylindole (DAPI)	Saimer Feishale
		FITC (fluorescein isothiocyanate)	Sigma aldrich tradeLimited Co.
DC2.4 cell line	Shanghai enzyme research Biotech Co., Ltd
		CT-26 cell line	Shanghai enzyme research Biotech Co., Ltd
TNF-alpha and IFN-gamma cytokine detection kit	Suzhoudaco is Biotech limited
		Sylgard 184 silicon rubber curing agent	Daokangning for curing disease
Multiwalled Carbon Nanotube (MCNT)	Scotch technologies, Inc. of Sozhou Gredler

Example 1: preparation of photothermal transfection substrate capable of desorbing cells

The transfection system used in the present invention is a virus-independent photothermal transfection system. Therefore, it is necessary to synthesize a substrate for photothermal transfection by a chemical synthesis method.

The photothermal transfection substrate provided by the present invention is a composite material, which comprises: (1) nanoparticles, and (2) a flexible substrate; the composite material comprises a composite material and a flexible base material, wherein the composite material comprises nano particles, the nano particles comprise one or more of multi-wall carbon nano tubes, graphene, gold nano particles and polydopamine nano particles, the flexible base material comprises one or more of thermosetting plastics such as polydimethylsiloxane and hydrogel, and the mass percentage of the nano particles in the composite material is 0-60 per thousand.

Multi-walled carbon nanotubes (MCNTs) were chosen as nanoparticles in this example because of their good dispersibility; polydimethylsiloxane (PDMS) has good biocompatibility, smooth surface topology, and easy cell detachment, so PDMS is selected as the flexible substrate in this embodiment.

In the preparation process of the photo-thermal material, firstly, a crosslinking agent of a PDMS precursor and a Sylgard 184 silicon rubber curing agent is mixed according to the mass ratio of 50: mixing at a ratio of 1-5: 1. When the proportion of the crosslinking agent is higher, the hardness of the obtained photothermal material is higher. In order to obtain proper hardness, PDMS precursor and cross-linking agent are mixed according to the mass ratio of 10:1, then poured into an ultrasonic cleaning machine for ultrasonic dispersion, and after uniform mixing, MCNT is added and then fully stirred uniformly. The mass ratio of MCNT in PDMS can be controlled within 0.5-10 per mill, for the convenience of observing cell state and maintaining good photothermal effect, MCNT with mass ratio of 10 per mill is selected as final concentration. Pouring the mixture into a culture dish, fully and uniformly stirring, and curing for 1h at 65 ℃. After demolding, the sample is cut into a circular sample with the diameter of one centimeter, washed with 95% ethanol and water for three times respectively, and then dried by nitrogen. Then at 1W/cm²、2W/cm²、3W/cm²And 4W/cm²The photothermal effect of the material at different times was tested at different laser intensities.

As can be seen from fig. 1, the photothermal intensity of the material prepared in this example varies with the variation of the laser intensity, the photothermal effect of the material prepared in this example increased with the increase of the laser intensity 40s before, and the difference after 40s was not significant.

Example 2: construction of a cell line for DC expressing Halotag Transmembrane Protein (HTP)

Construction of functional plasmids for transfection of DCs

Functional plasmids were designed for transfection of DCs. The specific design mode is as follows: a recombinant HTP plasmid (purchased from Suzhou science and technology limited, Jinzhi) is integrated into a pcDNA3.1 vector by a conventional molecular biological means, and an antibiotic neomycin (neomycin) gene is integrated and inserted for screening in late transfection of cells, wherein the recombinant pcDNA3.1 vector contains a heme (Hemagglutenin A epitope) gene as a marker gene which can be combined with fluorescein-labeled avidin (FITC-avidin) for verification of transfection efficiency.

Optimization of transfection conditions and acquisition of HTP-modified DC cells

The photothermal material prepared in example 1 above was sterilized, and then the sterilized substrate was immersed in a 20% by mass PBS solution containing 1% fetal bovine serum, incubated overnight at 37 ℃, and the supernatant was discarded. The plasmid DNA containing HTP prepared in the part 1 of this example was then coated with a small molecule Polyetherimide (PEI) at a plasmid concentration of 0.5-5. mu.g/10⁴The final selection of 1.5. mu.g/10 for optimal transfection efficiency and minimal plasmid usage was adjusted within the individual cells⁴The individual cell plasmid concentrations were experimental concentrations.

Spreading on the surface of the substrate treated in the example 1 for 1-3 h, and then planting dendritic cells on the substrate adsorbed with the plasmids according to a certain density, wherein the density of the dendritic cells can be 10⁴～10⁵Per cm²Within range of regulation, in order to achieve better transfection effect, the optimized condition is according to 5 multiplied by 10⁴Per cm²The dendritic cells are planted at a density of (1). And after the dendritic cells are attached to the wall, adding the PEI-coated plasmid DNA containing HTP again, and transfecting under a specific laser condition. Specifically, the intensity of the laser is set to be 1-10W/cm²The laser irradiation time is set to 5-60 s. Setting the laser intensity to 1-4W/cm due to the negative effect of excessively high laser intensity on cell activity²(ii) a And considering the transfection efficiency, the irradiation time of the laser is selected to be 20-60 s. In order to optimize transfection efficiency and cell activity, optimal condition selection was performed under the above conditions. Finally, the concentration is determined to be 2W/cm²The optimal reaction condition is that the cell transfection is carried out for 30s under the laser intensity of (1). After the transfection, the cells were placed in an incubator at 37 ℃ for further 48 hours to obtain HTP-modified DC cells.

From the effect data of fig. 2 it can be seen that: (1) the concentration of the plasmid has a more obvious influence on the transfection efficiency, compared with 2W/cm²Under the laser irradiation intensity, different plasmid concentrations (0.5. mu.g/10) were compared⁴1.0. mu.g/10 per cell⁴1.5. mu.g/10 per cell⁴Individual cell and 2ug/10⁴Individual cells) on transfection, indicating 1.5. mu.g/10⁴The best transfection efficiency was achieved for individual cells (see in particular A of FIG. 2). (2) Laser intensity also has different effects on transfection efficiency and cell activity, too much or too little laser intensity is not beneficial to transfection, too little laser intensity is not effective in cell transfection (see B in FIG. 2), and too high laser intensity affects cell activity (C in FIG. 2). (3) In addition, the time of laser irradiation was selected, and it was found that good transfection results were obtained in 30s, and the prolonged time did not significantly increase the transfection efficiency (see D in fig. 2).

As can be seen from FIG. 2, the plasmid concentration, the laser irradiation time and the laser intensity all affect the final transfection effect. Specifically, when the plasmid concentration is 1.5. mu.g/10⁴The transfection efficiency of each cell can reach about 95%, and the continuous increase of the plasmid concentration does not significantly improve the transfection efficiency (see A in FIG. 2). The laser intensity is 2W/cm²The transfection efficiency reached about 95%, and thereafter, the transfection efficiency tended to decrease as the laser intensity increased (see B in fig. 2). Cell viability after laser irradiation is another factor to be considered, at a laser intensity of 1W/cm²When the activity of the cells is close to 100%, 2W/cm²The amount of the compound is about 90%, and the cell activity tends to decrease with the increase of the laser intensity (see C in FIG. 2). The activity and transfection efficiency of the cells were compared in combination, 2W/cm²Is the most suitable laser intensity. Finally, comparing the laser irradiation time, it is found that the transfection efficiency is only 50% when the above conditions are irradiated for 10s, and the efficiency reaches more than 95% after 30s, and the continuous increase of the irradiation time does not significantly improve the transfection efficiency (see D in fig. 2).

Thus the final concentration of the final selection plasmid was 1.5. mu.g/10⁴Individual cell, 2W/cm²The laser intensity and the laser irradiation time were 30 seconds as the final transfection conditions.

3 comparison of transfection efficiency and cell Activity by different transfection systems

Based on the above test, the photothermal transfection system was compared with the transfection system of the viral vector, and the superiority of the transfection efficiency of the photothermal transfection system was verified.

The experimental group adopts a photothermal transfection system, transfection is carried out according to the optimized transfection conditions, a negative control group adopts lentivirus and recombinant HTP plasmid purchased from Suzhou science and technology limited Jinzhi to mix and transfect the DC, DC cells of an untransfected group are used as a blank control, and the transfection efficiency is verified by immunofluorescence staining after 48 hours. The specific process is that transfected cells are fixed by 5% paraformaldehyde for 10min, Triton breaks membranes for 5min, and HA primary antibody is incubated overnight, and then is stained by DAPI and FITC respectively and observed.

The results are shown in FIG. 3: the transfection efficiency of the photothermal transfection system reaches more than 90%, while the transfection efficiency of the viral transfection system is only less than 20% in the same time. As can be seen by comparing the two transfection systems, the activity of the photothermal transfection cell is reduced by less than 20%, and the activity of the virus transfection cell is reduced by about 30%, which shows that the photothermal transfection system has more advantages than the virus transfection system.

Example 3 Synthesis of functional glycomer molecules for modifying DC cells

The synthesis process of functional glycomer molecules for modifying DC cells requires chloroalkane-end modified chain transfer agents, sugar monomers and initiators. The synthesis of the sugar molecule for modifying the DC cell comprises the steps of firstly carrying out chloralkalation modification on a chain transfer agent, and then carrying out polymerization reaction on the chain transfer agent, the sugar monomer and an initiator which are subjected to chloralkalation modification under certain conditions to obtain a sugar polymer for DC modification. The resulting glycomer molecular weight was in the range of 2000-9000Da for subsequent studies. The specific experimental process is as follows:

(1) firstly, synthesizing a chain transfer agent containing a chloralkane structure.

2- (2-Boc-aminoethoxy) ethanol (4.30g, 20.95mmol), anhydrous THF (40mL) and anhydrous DMF (20mL) were added sequentially to mix at 0 deg.C NaH (60% dispersed in paraffin liquid, 1.12g, 28.00mmol), and after stirring at 0 deg.C for 30min, 1-chloro-6-iodohexane (4.80mL, 31.60mmol) was added to the mixture at 0 deg.CIn the above mixture. The mixture was stirred at 0 ℃ for a further 20min, at room temperature for 16h, then saturated NH was added₄The reaction was quenched with aqueous Cl and the mixture was extracted twice with ethyl acetate, washed with brine, dried over sodium sulfate and collected by filtration to give deprotected intermediate C.

0.5g of the chain transfer agents 4-cyanovaleric acid dithiobenzoic acid (CPADB), 0.33g of N-hydroxysuccinimide (NHS) and 0.74g of DCC were weighed out and dissolved in 10ml of anhydrous N, N-Dimethylformamide (DMF) and reacted at 30 ℃ for 12 hours, and the reaction was followed by thin layer chromatography. When the CPADB starting point disappeared in the reaction system, 0.387g of deprotected intermediate C was added in situ. Dropping deprotected intermediate product C, reacting at 30 deg.C overnight, washing with water, concentrating, and purifying with silica gel column chromatography. And purifying to obtain the chloralkane end modified RAFT chain transfer agent A.

(2) Synthesis of chloroalkane end functionalized glycomers.

0.1240g N-methacryloyl mannosamine (MAM) (0.5mmol), 0.0024g of chloroalkane modified RAFT chain transfer agent A prepared in step (1) above and 0.0004g of AIBN were weighed out in 3mL of anhydrous DMF and deoxygenated by bubbling nitrogen through the above solution for 30min, after which the reaction flask was transferred to a glove box and reacted at 70 ℃ for 12 h. After the reaction, the reaction solution was transferred to a dialysis bag with a molecular weight cut-off of 3500 for dialysis for 2 days, and the polymer was collected after lyophilization.

Figure 4 shows the molecular structure of the composition, namely polymannan, containing chlorinated alkane ligands; the molecular weight of the glycomer is about 5000 Da. Indicating the successful synthesis of polymannan with chloroalkanated ligands. Table 2 shows the molecular weight and Polymer Dispersity Index (PDI) distribution of the polymannan:

table 2: polymannan molecular weight and PDI distribution

(3) Preparation of modified DC with function of glycomer

The polymer (i.e., glycomer) synthesized in the step (2) above was dissolved in sterile PBS solution, the glycomer was added to the culture solution of the HTP-DC cells described in example 2 and the final concentration was adjusted to 0.1mg/mL, after 1 hour the culture solution was aspirated, washed with PBS 2 times, and the modified DC having the glycomer function was obtained by adding the normal culture solution.

Example 4: validation of glycomer and HTP-DC cell binding

In order to confirm the binding of the glycomer to HTP-DC cells, a biotinylated glycomer functionalized with chloroalkane termini was used to act on dendritic cells, and whether the action was produced was determined by an antigen-antibody fluorescence method.

To label the functional glycomer, a functional glycomer with a biotin label is first synthesized. The specific implementation process comprises the following steps: 0.1112g of N-methacryloyl mannosamine (MAM), 0.0257g of biotin monomer and 0.0004g of Azobisisobutyronitrile (AIBN) were weighed out and dissolved in 3mL of anhydrous DMF and 0.0024g of chloroalkane end-modified RAFT chain transfer agent A described in example 3 was weighed out and dissolved in 0.5mL of anhydrous DMF. Mixing the above solutions, and blowing N₂Oxygen was removed for 30 minutes. The reaction bottle is transferred to a glove box and reacts for 10 to 12 hours at the temperature of 70 ℃. After the reaction, the reaction solution was transferred to a dialysis bag with a cut-off molecular weight of 3500 for dialysis for 2 days, and then lyophilized to obtain a polymer.

According to the ratio of 5-10 ten thousand/cm²The cell density of HTP-DC cells were seeded in culture dishes. Culturing in 5% carbon dioxide and 37 deg.C incubator, attaching overnight, adding sterile PBS to wash cells twice, adding the synthesized glycomer without cells, setting the concentration of glycomer solution to 0.1-0.5 mg/mL, incubating at 37 deg.C for 1h, adding 200 μ l sterile PPS after incubation to wash cells, removing unbound polymer, adding FITC solution into the well plateThe FITC solution is obtained by mixing FITC dye and PBS (1% fetal calf serum) according to any ratio of 1: 20-1: 50, and specifically, mixing the FITC dye and the PBS according to a ratio of 1: 36. Cells were incubated at 4 ℃ for 1 h. And (3) labeling and imaging the cells by utilizing the combination of FITC and biotin, washing the labeled cells by sterile PBS, and observing the green fluorescence distribution condition on the surface of the cell membrane by using a laser confocal microscope to determine the grafting efficiency of the cells.

FIG. 5 shows fluorescence characterization of modified DCs. The glycomer was attached with a fluorescent label and the glycomer was observed for grafting under a fluorescent microscope. Cell membrane surface fluorescence is a labeled glycomer.

As can be seen in FIG. 5, after co-incubation of glycomer with HTP-DC, bright fluorescence on the cell surface was observed by FITC staining, whereas no fluorescence was detected by FITC staining after co-incubation of glycomer with unmodified DC, indicating that the glycomer molecules can be effectively anchored to the cell membrane surface by incubation.

Example 5: effect of glycomer-modified DCs on T cell immune activation Induction efficiency

To verify the immune activation efficiency of T cells under different DC induction conditions, the proliferation efficiency of T cells was first verified.

The CT26 cells are lysed to obtain whole cell antigens, and then the whole cell antigens are added into a 1640 culture medium to culture the DC cells, and the DC cells are induced to mature after 48 hours of culture. T cells were harvested from mouse spleen, and DC cells after staining with CSFE and after induction maturation were stained according to 1: and (5) culturing for 48h, collecting the T cells, and analyzing the proliferation efficiency of the T cells according to the distribution of fluorescence intensity and cell number detected by flow cytometry.

The experimental component groups were set as: (1) unmodified DC group (DC); (2) unmodified DC + CpG adjuvant group (DC-CpG); (3) lentivirus-transfected CD 28-modified DC group (CD 28-DC); (4) the group of polymannan modified DCs (pMAM-DC).

The result shows that the proliferation efficiency of the polymannan pMAM modified DC induced T cells is far higher than that of the traditional adjuvant and virus transfection system. About twice as much as the conventional method (see a in fig. 6).

To further verify the induction of T cell differentiation capacity, the supernatant after the above culture was used for the detection of the cytokines TNF- α and IFN- γ (see the instructions of the ELIZA kit for TNF- α and IFN- γ for specific methods).

TNF-alpha and IFN-gamma detection method: firstly, cell culture supernatant is taken, ELIZA of TNF-alpha and IFN-gamma is adopted for detection, and the specific steps are as follows, firstly, a standard curve is made by using a standard substance, and then, a sample is added into a pore plate for incubating an antibody.

The results showed that pMAM-modified DCs induced T cell TNF- α secretion 10-fold higher than unmodified DCs, about 2-3-fold higher than conventional CpG and viral transfection systems (see B in FIG. 6). Meanwhile, the results show that the expression level of IFN-gamma can be more efficiently expressed in the DC induced by the glycomer, about 8 times of that of the unmodified DC, and more than 2 times of that of the traditional CpG and virus modification (see C in figure 6).

As can be seen from FIG. 6, the proliferation induction efficiency of mature DC to T cells can be increased by about 80% with the help of adjuvant CpG, and after the DC is modified by CD28, the proliferation induction efficiency to T cells can be increased by nearly 1 time, and the proliferation induction efficiency to T cells is increased by nearly 4 times with the help of DC modified by glycomer. In addition, the modified DC significantly promoted expression of T cell activating factor. Under the action of an adjuvant, the expression levels of TNF-alpha and IFN-gamma can be improved by about 4 times, the expression levels of TNF-alpha and IFN-gamma of DC cells modified by CD28 can be improved by about 4 times, and the expression levels of TNF-alpha and IFN-gamma of DC cells modified by glycomer can be improved by about 8 times. The glycomer modified DC can remarkably promote the proliferation and the activation of T cells.

Example 6: effect of glycomer-modified DC-induced T cells on killing Activity of specific tumor cells

The DCs harvested in example 5 were co-cultured with T cells and with colon cancer cells, CT26 cells. And observing the growth of the tumor cells after 24h, including the shape, the number and the size, detecting Lactate Dehydrogenase (LDH) of the culture supernatant, and sequentially analyzing the apoptosis condition of the tumor cells.

The experimental components were as follows: (1) group of colon cancer cells: CT26 cells not mixed with vaccine; (2) cpg-mature DC vaccine group: namely, the DC vaccine mixed by adding an adjuvant Cpg into CT26 cells; (3) virus-transfected DC vaccine group: namely, the addition of lentivirus-transfected CD28 modified DC vaccine to CT26 cells, (4) modified DC vaccine group: namely CT26 cells, and adding a polymannan modified DC vaccine.

Specifically, each group of activated T cells and CT26 cells were mixed according to the ratio of 2: 1 in a 48-well plate, simultaneously setting independent T cells and CT26 cells as blank controls, placing the blank controls in a cell culture box for continuous culture for 24h, detecting the absorbance value at 450nm in each group by using an LDH detection kit, and comparing the killing rate of the T cells induced by different methods to tumors.

The killing rate was (CT26 cell OD value + T cell OD value-experimental OD value)/CD 26 cell OD value × 100%.

As can be seen from FIG. 7, the adjuvant-assisted DC vaccine has a certain killing effect on CT26 cells, the apoptosis rate of tumor cells is close to 40%, and the DC vaccine obtained by virus modification has similar results. And the killing rate of T cells obtained by the glycomer modified DC to tumor cells is as high as 80%. The modified DC induced T cells are shown to have higher tumor killing capacity.

As can be seen from fig. 7, the T cells induced by the modified DC have higher toxicity to the tumor cells, and the viability of the tumor cells is reduced by about 80%, while the T cells induced by the adjuvant-assisted DC and the virus-transfected DC have certain toxicity to the tumor cells, and the viability of the tumor cells is reduced by about 50%. Indicating that the glycomer-modified DC induced T cells have higher tumor toxicity than previous methods. And as can be seen from a in fig. 7, T cells induced by the glycomer-modified DC have a strong tumor killing effect, while T cell tumor killing effects induced by methods such as viral transfection and adjuvant assistance are not very significant. These results indicate that modifying DCs with glycomers as vaccine formulations will exert a stronger tumor killing effect than the traditional approach.

Claims

1. A method for modifying dendritic cells based on a cell membrane surface modification technology, the method comprising the following steps:

1) synthesizing a substrate for photothermal transfection;

3) preparing a modified dendritic cell;

4) synthesizing functional glycomer molecules;

2. The method for modifying dendritic cells based on cell membrane surface modification technology according to claim 1, wherein the method for preparing the substrate in step 1) comprises:

3. The method for modifying dendritic cells based on cell membrane surface modification technology according to claim 1 or 2, wherein the concentration of the plasmid in the step 2) is 0.5-2 μ g/10⁴Cells, and the time for placing the plasmid on the surface of the substrate in the step 1) is 1-3 h; preferably, the concentration of the plasmid is 1.5. mu.g/10⁴And (4) cells.

4. The method for modifying dendritic cells based on cell membrane surface modification technology according to any one of claims 1 to 3, wherein the specific operation of step 3) is: inoculating dendritic cells on the surface of the substrate containing the plasmids in the step 2), adding PEI again after the dendritic cells are attached to the wall, transfecting under laser, and continuously culturing the cells for 36-60 h, wherein the PEI coats the plasmids containing the gene sequences for coding HTP;

5. The method for modifying a dendritic cell based on a cell membrane surface modification technique according to any one of claims 1 to 4, wherein the method for preparing the functional glycomer molecule in the step 4) comprises:

6. The method for modifying dendritic cells based on cell membrane surface modification technique according to claim 5, wherein biotin monomer is added to the polymerization reaction in (iii).

7. A dendritic cell produced by the method according to any one of claims 1 to 6.

8. A vaccine composition comprising the dendritic cell of claim 7 and one or more pharmaceutically acceptable carriers, adjuvants and/or excipients.

9. Use of the dendritic cell of claim 7 in the manufacture of a medicament for the treatment and prevention of a malignant tumor.

10. The use according to claim 9, wherein the malignant tumor is any one of lung cancer, liver cancer, colon cancer, melanoma, prostate cancer, stomach cancer, breast cancer, Chronic Lymphocytic Leukemia (CLL) or chronic granulocytic leukemia; preferably, the malignant tumor is colon cancer.