Summary of the invention:
In order to address the above problem, the present inventor is cross-linked to humanized SM5-1 monoclonal antibody on the nanoparticle USPIO of preparation, prepares the MRI contrast medium with targeting, called after SM-USPIO.MRI by flow cytometry, Laser Scanning Confocal Microscope observation and cultured cell in vitro confirms can combine by the tumor cell specific of crosslinked antibody with the SM5-1 antigen positive at external SM-USPIO, and can be by the tumor cell endocytosis; Behind the injection SM-USPIO, MRI result shows that the T2 signal of tumor tissues obviously reduces, so SM-USPIO can be used for the in-vivo diagnostic of SM5-1 antigen positive tumor in the tumor-bearing mice body.
More specifically, the invention discloses:
1. mr contrast agent SM-USPIO based on humanized antibody, for humanization SM5-1 anti-
Body and superparamagnetic iron oxide particle USPIO are crosslinked and get.
2. the preparation method of above-mentioned 1 described mr contrast agent SM-USPIO may further comprise the steps:
Step a: preparation superparamagnetic iron oxide particle USPIO,
Step b: the preparation humanized antibody,
Step c: preparation mr contrast agent SM-USPIO.
3. the preparation method of above-mentioned 2 described mr contrast agent SM-USPIO, wherein the preparation of superparamagnetic iron oxide particle USPIO obtains by coprecipitation method among the step a:
Steps A: glucosan is dissolved in the water, adds iron salt, stir;
Step B: under the condition of heating, polyvinyl alcohol is dissolved in the water;
Step C: mix in the solution that the solution adding steps A that step B is obtained obtains, use alkali
Transfer pH to 10-12, continue to stir post-heating and obtain precipitation;
Step D: the collecting precipitation thing also carries out post processing to it.
4. the preparation method of above-mentioned 3 described mr contrast agent SM-USPIO, wherein the iron salt that uses in the steps A is FeCl
36H
2O and FeSO
47H
2O, wherein ferric iron and ferrous mol ratio are to be 3:2.
5. the preparation method of above-mentioned 3 described mr contrast agent SM-USPIO, wherein the alkali described in the step C is ammonia.
6. the preparation method of above-mentioned 3 described mr contrast agent SM-USPIO is wherein utilized magnetic field collecting precipitation thing among the step D.
7. the preparation method of above-mentioned 3 described mr contrast agent SM-USPIO, wherein post-processing step comprise utilize washing, with the resuspended precipitation of citric acid solution, ultrasonic, unnecessary citric acid is removed in dialysis in deionized water.
8. the preparation method of above-mentioned 2 described mr contrast agent SM-USPIO, wherein the step c step for preparing mr contrast agent SM-USPIO comprises UPSIO is activated, and separates the particle after the activation, and particle and the PBS that contains antibody are mixed, stir, handle and get through the magnetic post.
9. above-mentioned 1 the purposes of mr contrast agent SM-USPIO aspect diagnosing tumor.
10. above-mentioned 9 purposes, wherein tumor is the conjugated protein male tumor of SM5-1.
The present inventor is crosslinked with the superparamagnetic iron oxide particle (USPIO) of humanized SM5-1 antibody and coprecipitation acquisition, has obtained a kind of targeting MRI contrast medium of nanoscale, called after SM-USPIO.Its average aquation diameter is 25.3nm, and this nanoscale has guaranteed interior long cycle period of its body and targeting efficient.
The present inventor utilizes several different methods to detect the SM-USPIO specific binding capacity.The flow cytometry result shows, compares with free humanization SM5-1 monoclonal antibody, and SM-USPIO has similar and the bonded ability of the conjugated protein positive human hepatoma carcinoma cell of SM5-1 ch-hep-3, and the result of reference substance H-USPIO is negative.In different cell strains, the average fluorescent strength after SM-USPIO handles and the protein-bonded expression positive correlation of SM5-1 of each cell; But the result of Laser Scanning Confocal Microscope shows the SM-USPIO specificity and is incorporated into the conjugated protein male tumor cell of SM5-1, and can be by this cell endocytic.MRI detect to confirm that the positive tumor cell that SM-USPIO handled has tangible T2 signal weakening, adds humanization SM5-1 monoclonal antibody and does not have this effect and contrast contrast medium H-USPIO and blank contrast medium USPIO.Above results suggest SM-USPIO can enter and accumulate the conjugated protein positive human hepatoma carcinoma cell in SM5-1 by antibody-mediated endocytosis; The T2 signal weakening that occurs tumor region in the tumor-bearing mice behind the injection SM-USPIO, and
125The SM-USPIO of I labelling also obviously is gathered in the tumor cell, and therefore, SM-USPIO can enter by antibody-mediated endocytosis and accumulate in tumor by local equally in vivo, the effect of performance MRI radiography contrast medium.
Above-mentioned result of experiment shows, the USPIO of crosslinked humanization SM5-1 monoclonal antibody can be used for the diagnosis of the conjugated protein male tumor of SM5-1.
Thereby other have tumor high specific targeting antibodies also can carry out the crosslinked diagnosis that is applied to tumor by method disclosed by the invention and USPIO, and these tumor high specific targeting antibodies include but not limited to the anti-Her-2 monoclonal antibody of high-affinity, high-affinity monoclonal antibody against EGFR etc.
The specific embodiment
Following examples, experimental example only further specify the present invention, should not be construed as limitation of the present invention.
Materials and methods:
Cell, antibody and other materials:
Hepatoma cell line ch-hep-1, ch-hep-3 and ch-hep-6 are set up by the The 2nd Army Medical College institute of oncology and provide, the protein-bonded expression difference of these cell lines SM5-1 separately, ch-hep-3 high expressed wherein, the ch-hep-6 medium level is expressed, and ch-hep-1 is negative, its open source information is referring to Zhao J, Wang H, Wei L, et al.The cytotoxic effect of E1B 55-kDa mutant adenoviruson human hepatocellular carcinoma cell lines, Cancer Gene Ther 2001; 8:333-341, humanized SM5-1 antibody prepares Li B by literature method, Wang H, Zhang D, et al.Construction and characterizat ion of a high-affinity humanized SM5-1monoclonal antibody.Biochem Biophys Res Commun 2007; 357:951-6.The goat anti-human igg of FITC labelling (H+L) available from Zymed company (San Francisco, CA).Humanized anti-Her2 antibody is according to Chinese invention patent application number 01132225.X, and denomination of invention is disclosed method preparation in " Humanized anti-HER 2 monoclonal antibody and method for making thereof and pharmaceutical composition ".The organic solvent of using in the experiment is the HPLC level, and other reagent are the highest level that can buy.
Laboratory mice is that the Balb/c nude mice (18-22 gram) in 6-8 ages in week available from the The 2nd Army Medical College Experimental Animal Center, is raised in this center by the SPF rank.All zooperies all obtain the approval of management of laboratory animal committee of The 2nd Army Medical College.
Transmission electron microscope: JEM-100CX, Japanese JEOL company;
Laser light scattering particle size analyzer: Zeta Sizer 3000HS, Malvern Instruments, UK;
Flow cytometer: Becton-Dickinson, San Jose, CA;
Laser Scanning Confocal Microscope: Zeiss CLSM 510, German Zeiss company;
4.7T Bruker Biospec
AvanceToy magnetic resonance imaging system: Bruker Biosciences, Germany;
Gamma counter: HPGe ADCAMTM918 type, U.S. ORTEC company.
Embodiment 1 USPIO, the preparation of SM-USPIO and H-USPIO
USPIO prepares by coprecipitation method in containing the solution of glucosan, and it comprises the core of ferrum oxide and the low-molecular-weight glucosan of outer parcel.1 gram glucosan (molecular weight 40kDa) is dissolved in the 15ml deionized water, adds FeCl
36H
2O 24.35mg and FeSO
47H
2O 16.68mg stirs under nitrogen protection.Polyvinyl alcohol (Polyyinyl Alcohol; molecular weight 1750 ± 50) under 80 ℃ condition, prepares saturated solution in the adding deionized water; get 10ml and mix, under nitrogen protection and lasting condition of stirring, drip 7% ammonia adjusting pH to 10-12 with above-mentioned solution.After black iron oxide particle occurs, continue to stir 10 minutes, be heated to 85 ℃ afterwards and kept 60 minutes; By magnetic field results precipitate, the deionized water wash number is all over to remove the soluble iron ion.With citric acid solution (1 gram citric acid is dissolved in the 30ml deionized water) the resuspended precipitation of 30ml, ultrasonic 20 minutes of 700w, the product that obtains dialyse 48 hours to remove unnecessary citric acid in the 1L deionized water; Finally, to be adjusted to 0.25mol/L by concentration of iron standby for the USPIO of acquisition.
Humanized SM5-1 antibody is crosslinked as follows on the humanized SM5-1 antibody of preparation, antibody is dissolved in PBS (the 5mmol/L phosphate of pH7.4 by the concentration of 5mg/ml, 0.9% sodium chloride) in, EDC (1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide Hydrochloride, 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimides) and NHS (N-hydroxysulfosuccinimide, N-N-Hydroxysuccinimide) all is dissolved in PBS (the 5mmol/L phosphate of pH6.0 by the concentration of 50mg/ml, 0.9% sodium chloride) in, get the 1mlUSPIO suspension, mix with above-mentioned EDC/NHS solution 2.5ml, stirring at room 30 minutes is with the activation particle; The PD-10 desalting column is removed unnecessary activator on the reactant liquor afterwards, separate the particle after activating, particle is scattered among the PBS of 3ml, the antibody that adds the above-mentioned preparation of 300 μ l immediately, stirring at room 2 hours, particle is through magnetic post (Miltenyi Biotech GmbH, Germany) (by specification operation, be no more than magnetic column flow rate restriction) and deionization washing multipass to remove unconjugated antibody, the USPIO (called after SM-USPIO) that combines humanized SM5-1 antibody at last is resuspended among the 10mmol/L PBS of pH7.4, and it is standby to be adjusted to 0.25mol/L by concentration of iron once more.(Pierce, Rockford IL) measure the protein concentration of magnetic post stream in putting on clearly and obtain the concentration of unconjugated SM5-1 humanized antibody, and can therefore calculate the crosslinked amount of antibody on the cross-linking efficiency of antibody and the particle by the MicroBCA protein determination kit; Identical method is crosslinked humanization anti-Her2 antibody on USPIO, obtains particle called after H-USPIO.
The particle diameter of nanoparticle and structure obtain by transmission electron microscope and laser light scattering particle size analyzer.
Transmission electron microscope results shows that the ferrum nuclear diameter of SM-USPIO is 8-10nm (Fig. 1-1), the laser light scattering particle size analyzer show its hydration radius be 25.3 ± 2.1nm (98% between 17nm~50nm) (Fig. 1-2).It is 14mg Fe/ml that SM-USPIO is adjusted to concentration, and promptly the concentration of iron of 0.25mmol/ml is preserved, and antibody concentration is 10 ± 2 μ g/mg Fe, and the crosslinking rate of antibody is 60%; During preservation, the mannitol that has added the aqueous citric acid solution of 4.16mg/ml and 60mg/ml in the system is as stabilizing agent; The result proves that SM-USPIO can stablize June at ambient temperature.
The radioactive label experiment of experimental example 1 targeting USPIO
By chlorine ammonia-T method (Hunter WM, Greenwood FC (1962) .Preparation of iodine,
131I-labelled human growth hormone of high specific activity.Nature 194:495-496) uses
125I-Na carries out labelling to SM-USPIO and H-USPIO, and (Miltenyi Biotech GmbH, Germany) separation is removed free still to adopt the magnetic post behind the labelling
125I-Na, SM-USPIO behind the labelling and H-USPIO are used for the metabolism experiment.
The activity experiment that combines of experimental example 2 Flow cytometry SM-USPIO and the conjugated protein high expressing cell of SM5-1
1 * 10
6The cell of/ml (ch-hep-3) was hatched 1 hour for 4 ℃ with the PBS of 0.1ml, humanization SM5-1, the SM-USPIO or the H-USPIO that contain 10 μ g/ml respectively (all calculate with the antibody amount, comprise free and be combined on the particle), hatched 30 minutes for 4 ℃ with the goat anti-human igg (H+L) of FITC labelling behind the cell washing, cell washs back machine testing on the FACScan flow cytometer once more.
The result shows and sees Fig. 2-1, the result shows with there was no significant difference between the cell of H-USPIO processing and the PRS processed group, the ch-hep-3 cell of SM-USPIO and humanization SM5-1 antibody treatment shows very high fluorescence intensity, and PBS and H-USPIO processed group are all negative, SM-USPIO is similar to free antibodies with the protein-bonded binding ability of SM5-1 in prompting, and this results suggest humanization SM5-1 antibodies has still kept itself and the protein-bonded high-affinity of SM5-1 behind the US PIO.
Afterwards, we have detected the binding ability (method is the same) of SM-USPIO again on three strain SM5-1 binding protein expression levels different human liver cancer cell ch-hep-1, ch-hep-3, ch-hep-6, the result is shown in Fig. 2-2, and the result shows that the average fluorescent strength of the cell that SM-USPIO handles and the SM5-1 binding protein expression level of cell match.The SM5-1 binding protein expression level of Ch-hep-3 is the highest, and its average fluorescent strength is also the highest; The SM5-1 binding protein expression feminine gender of ch-hep-1, its average fluorescent strength is negative; The SM5-1 binding protein expression level of ch-hep-6 is medium, and its average fluorescent strength is between between the two.This result shows that SM-USPIO combines with target cell and has good specificity.
Experimental example 3 utilizes Laser Scanning Confocal Microscope to detect the conjugated protein endocytosis SM-USPIO experiment of SM5-1
For whether checking Ch-hep-3 cell can pass through the conjugated protein endocytosis SM-USPIO of SM5-1, we have carried out the Laser Scanning Confocal Microscope observation to it: Ch-hep-3 cell (1 * 10
5) hatched altogether 1 hour for 37 ℃ with SM-USPIO, H-USPIO or each 0.1ml of PBS (in the antibody amount) of 10 μ g/ml, the PBS washing, fix 10 minutes for 4 ℃ with 4% paraformaldehyde, carried out rupture of membranes in 5 minutes with 0.1% TritonX-100 incubated at room afterwards and handle, subsequently with 1% bovine serum albumin sealing 30 minutes; At room temperature hatched 2 hours with the sheep anti-mouse igg of FITC labelling again, PBS washing, cell is observed and is taken pictures through fixing, mounting and by Zeiss 510 laser scanning co-focusing microscopes.
The result as shown in Figure 3, the result shows that ch-hep-3 cell simple resisting with two of FITC labelling hatch, cell does not have obvious background fluorescence and occurs, but before two anti-hatching, cell and SM-USPIO were hatched 1 hour altogether at 37 ℃, tangible fluorescence then appears in cell cytosol, the cell that H-USPIO handles then with the negative cells zero difference, this explanation SM-USPIO can combine with the ch-hep-3 cell and specifically by cell internalizing.
Experimental example 4 nuclear magnetic resonances experiment
For external imaging, 1 * 10
5Cell (be respectively ch-hep-1, ch-hep-3, ch-hep-6) hatched 1 hour with following composition under 37 ℃ of conditions: SM-USPIO, H-USPIO, USPIO, USPIO add humanization SM5-1 antibody and PBS, cell is through three washings, fix with 4% paraformaldehyde after the trypsinization, 1000rpm made it to become a cell mass in centrifugal 5 minutes in centrifuge tube, add one deck 1% agarose in the above.Same a kind of cell harvesting of different condition is in the different aspects of same pipe.Nuclear magnetic resonance is at 4.7T BrukerBiospec
AvanceCarry out on the toy magnetic resonance imaging system, adopt the spiral echo sequence.Vow the dress bit image for the T2 weighting, adopt following imaging parameters: matrix=128 * 128 μ m, FOV=45 * 45mm, sectionthi ckness=1mm, TE=45ms, TR=3000ms, number of average=1.
Experimental result as shown in Figure 4, demonstration be the sagittal t2 weighted image of cell mass in the agarose.Hatched 1 hour with the SM-USPIO (calculating by iron content) of 50 μ g/ml before the cell harvesting, matched group comprises that PBS, USPIO, H-USPIO and USPIO add humanization SM5-1 antibody, and its concentration is all calculated by iron content or antibody amount, and is consistent with SM-USPIO dosage.On the image of ch-hep-3 cell pipe, the cell mass that SM-USPIO handles shows tangible low signal, and other four cell masses all show as high signal.On the image of ch-hep-1 cell pipe, 5 cell masses show identical high signal.On the image of ch-hep-3 cell pipe, the signal of the cell mass that SM-USPIO handles is lower slightly than the signal of other four cell masses, but the corresponding ch-hep-3 cell that is far from is obvious.In three kinds of cells, the decline of signal does not all appear in the cell that U5PIO adds humanization SM5-1 antibody treatment, this explanation is in short relatively incubation time, and cell can not initiatively be engulfed free USPIO, and free humanization SM5-1 antibody can not engulfed USPIO by mediated cell yet.Therefore, the USPIO that has only humanization SM5-1 antibody crosslinked just can by the conjugated protein positive cells of SM5-1 specifically in conjunction with and engulf.
The experiment of experimental example 5 in-vivo imagings
What use in the in-vivo imaging experiment is the lotus tumor Balb/c nude mice of inoculation human liver cell hepatocarcinoma ch-hep-3.Balb/c nude mice subcutaneous vaccination 2 * 10
6The ch-hep-3 cell, inoculate back 25 days after the about 5mm of diameter of tumor.The MRI contrast medium SM-USPIO or the H-USPIO of tail vein injection preparation this moment, dosage is 200mg Fe/kg.Animal was with the barbital sodium intraperitoneal anesthesia before MRI checked, radiography reaches injection respectively before injection carried out in back 2 hours, 8 hours, 24 hours and 72 hours, used 4.7T Bruker Biospec equally
AvanceThe toy magnetic resonance imaging system, parameter is as follows: TR=3000ms, TE-52ms, number of average=2, FOV=3.5 * 3.5cm, matrix=128 * 128 μ m.Three of every treated animals.
Experimental result sees that Fig. 5 result shows that the signal difference of tumor tissues and near muscular tissue is little, injects back 8 hours, and descending appears in the signal of tumor region, injects back 72 hours, and the signal of tumor region obviously descends, and tumor border is clear.The experiment contrast group adopts the H-USPIO of injection same dose in identical model, the result shows before and after the injection, the signal of tumor region does not have significant change, and prompting H-USPIO in this model does not have targeting potentiation, and SM-USPIO has tangible targeting potentiation.
The experiment of experimental example 6 biodistribution
125The biodistribution of I labelling SM-USPIO is also carried out on the lotus tumor Balb/c nude mice of inoculation human liver cell hepatocarcinoma ch-hep-3.Inoculate back 25 days, 12 animals are divided into 2 groups at random, and one group through tail vein 1.0 μ Ci's
125The SM-USPIO of I labelling, the same dosage of another group injection
125The H-USPIO of I labelling.Every treated animal was put to death 3 of animals in back 8 hours and 72 hours in injection respectively, got tumor tissues and each normal structure, comprised lung, the heart, liver, spleen, pancreas, stomach, colon and kidney, weighed and measured radioactivity.Each animal of putting to death in 72 hours is got the hematometry radioactivity injection back 5 minutes, 1 hour, 4 hours, 8 hours, 24 hours and 72 hours through cutting tail respectively.Radioactivity is measured by gamma counter.The radioactivity of each organ is represented with the percent of injected dose.
Statistical analysis: adopt the t check, with the standard of P<0.05 as significant difference.Result of the test is seen Fig. 6.
Fig. 6 show with
125The H-USPIO of I labelling compares,
125The SM-USPIO of I labelling injected back 8 hours and 72 hours tumor by local accumulation showed increased (P<0.05) (Fig. 6-1,6-2).The accumulation of tumor by local is progressively, with time correlation, injects after back 72 hours and can reach 8.9 ± 2.3%ID g
-1(ID pointed injection dosage, ID g
-1Refer to average every gram tissue injection dosage), be higher than the liver of same time and the summary accumulation level of spleen far away.On the contrary,
125The H-USPIO of I labelling is obviously low in the accumulation of tumor by local, and injects back 72 hours level and be lower than the back 8 hours level of injection.
125The SM-USPIO of I labelling and
125The distribution unanimity of the H-USPIO of I labelling in normal structure,, inject back 72 hours level and all be lower than the back 8 hours level (Fig. 6-1,6-2) of injection.
125The SM-USPIO of I labelling and
125The clearance curve unanimity (Fig. 6-3) of the H-USPIO of I labelling in blood.For comparing
125The SM-USPIO of I labelling and
125The cumulative difference of the H-USPIO of I labelling specificity in tumor tissues, we have calculated radioactivity ratio in same temporal lesion tissue and the blood.Injected back 72 hours,
125The tumor of the SM-USPIO treated animal of I labelling/blood ratio is 4.93 ± 0.79, and
125The tumor of the H-USPTO treated animal of I labelling/blood ratio is 1.26 ± 0.47, and the former is much larger than the latter (P<0.01).