Application of 89Zr-labeled umbilical cord mesenchymal stem cells in preparation of systemic sclerosis pharmacokinetic tracing reagent

Abstract

The invention discloses an application of 89Zr-labeled umbilical cord mesenchymal stem cells in preparation of a systemic sclerosis pharmacokinetic tracing reagent. The radiochemical purity of the radionuclide 89Zr-labeled umbilical cord mesenchymal stem cells is greater than or equal to 90%, the cell activity is greater than or equal to 90%, and the in-vitro 24-hour retention rate is greater than or equal to 85%. The in-vivo distribution rule of the human umbilical cord-derived mesenchymal stem cells is detected, and a relationship is established between dynamic distribution of the marker after the cells enter the body and the cell curative effect, so that the clinical curative effect of a cell drug is effectively improved, the risk is reduced, and the drug interaction is reduced. A visual and reliable technical means is provided for evaluating targeting and efficacy of stem cell treatment, and the method has important clinical research and transformation values.

Description

Technical Field

[0001] This invention relates to the fields of biomedicine and nuclear medicine, specifically to... 89 Application of Zr-labeled umbilical cord mesenchymal stem cells in the preparation of pharmacokinetic tracers for systemic sclerosis. Background Technology

[0002] Stem cell transplantation therapy has shown great potential in treating autoimmune diseases such as systemic sclerosis. However, the distribution of intravenously infused mesenchymal stem cells in vivo remains unclear. Traditionally, it is believed that they first accumulate in the lungs and are subsequently taken up by organs such as the liver and spleen. Currently, there is a lack of direct in vivo imaging evidence regarding the distribution of umbilical cord-derived mesenchymal stem cells in patients with systemic sclerosis and whether they can specifically home to lesions such as those in the skin.

[0003] 1. Existing assessment methods, such as tissue staining or quantitative PCR in preclinical studies, and biopsy, serum biomarkers, or routine imaging examinations in clinical practice, all have significant limitations:

[0004] (1) qPCR is mainly used in non-clinical research, and the experiment requires a large number of animals. In clinical research, qPCR can only analyze blood samples and cannot provide information on the spatial distribution of stem cells in specific organs such as liver, heart, spleen, and lungs. Moreover, the detection usually depends on sex chromosome differences (such as using Y chromosome genes to track male-derived cells), so it is only applicable to specific transplantation scenarios of "male donor-female recipient", and its application scope is greatly limited.

[0005] (2) Although there are currently 111 In-oxine, 99m Tc-HMPAO, 18 Radionuclide labeling methods such as F-FDG are used to explore the distribution of cells in vivo. However, these radionuclide labels are highly radioactive and can cause significant damage to labeled cells. High radiation doses may alter the normal biological behavior of cells, leading to instability in experimental results. Furthermore, they can cause significant physical harm to patients, resulting in low safety.

[0006] 2. Currently, there is no effective method to explore the dynamic distribution of mesenchymal stem cells in patients with systemic sclerosis and to assess their therapeutic effects.

[0007] (1) In animal models of systemic sclerosis, the dynamic distribution of mesenchymal stem cells was mainly detected by qPCR.

[0008] However, data from animals cannot directly predict the distribution of mesenchymal stem cells in the human body;

[0009] (2) There is no effective method in clinical practice to explore the dynamic distribution of mesenchymal stem cells in patients with systemic sclerosis. The pharmacokinetic characteristics of mesenchymal stem cells in patients with systemic sclerosis cannot be obtained. There is no clear evidence that mesenchymal stem cells can home to diseased skin tissue. Therefore, the therapeutic effect of mesenchymal stem cells cannot be judged, and it cannot guide precise drug use in clinical practice.

[0010] 3. CN113797360A discloses the technology. 89 Zr-labeled cardiomyocytes were used to label cardiomyocytes and for pharmacokinetic tracking; however, this method differs significantly from the present invention in that it cannot predict the in vivo distribution of mesenchymal stem cells in systemic sclerosis.

[0011] (1) Use in the disclosed technology 89 Zr-labeled cardiomyocytes are different from the mesenchymal stem cells of the present invention, and the two types of cells have different mechanisms of action;

[0012] (2) The disclosed technology uses cryopreserved cardiomyocytes, which are greatly damaged after cryopreservation and may change the biological characteristics of cardiomyocytes in vivo. The present invention uses fresh stem cell preparations.

[0013] (3) The infusion method used in the disclosed technology is significantly different from that used in this invention, which uses intravenous infusion;

[0014] (4) The diseases treated in the disclosed technologies are different from those treated in this invention. The mesenchymal stem cells used in this invention are used to treat systemic sclerosis.

[0015] In summary, these methods are either invasive, cannot be dynamically replicated, or lack the ability to specifically trace the therapeutic cells themselves, making it difficult to confirm in real time and visually whether stem cells have reached and remained in the skin target area, resulting in a "black box" state for treatment evaluation.

[0016] Currently, in preclinical research and clinical applications of systemic sclerosis (SSC), there is a lack of a method for long-term, highly sensitive, highly stable, low-toxicity, and reproducibly quantifiable monitoring of the systemic distribution of transplanted umbilical cord mesenchymal stem cells. This technological bottleneck hinders a deeper understanding of the pharmacokinetics of umbilical cord mesenchymal stem cells in SSC patients and limits the updating and advancement of methods for evaluating the efficacy of stem cell therapy regimens. Summary of the Invention

[0017] The purpose of this invention is to address the aforementioned shortcomings of the prior art by providing a method using radionuclides. 89 Application of Zr-labeled umbilical cord mesenchymal stem cells in the preparation of pharmacokinetic tracers for systemic sclerosis.

[0018] Another object of the present invention is to provide radionuclides 89 A method for pharmacokinetic tracing of systemic sclerosis using Zr-labeled umbilical cord mesenchymal stem cells.

[0019] The objective of this invention can be achieved through the following technical solutions:

[0020] With radioactive nuclides 89 Application of Zr-labeled umbilical cord mesenchymal stem cells in the preparation of pharmacokinetic tracers for systemic sclerosis.

[0021] Preferably, the umbilical cord mesenchymal stem cells are derived from a preparation of fresh umbilical cord mesenchymal stem cells and do not contain DMSO.

[0022] Preferably, the radionuclide 89 Zr-labeled umbilical cord mesenchymal stem cells had a radiochemical purity of ≥90%, cell viability of ≥90%, and an in vitro 24-hour retention rate of ≥85%.

[0023] Preferably, the pharmacokinetic tracer for systemic sclerosis is used to evaluate the in vivo efficacy and distribution kinetics of umbilical cord mesenchymal stem cell therapy for systemic sclerosis, and to observe the homing of umbilical cord mesenchymal stem cells to diseased skin tissue in order to determine its therapeutic effect.

[0024] With radioactive nuclides 89 A method for pharmacokinetic tracing of systemic sclerosis using Zr-labeled umbilical cord mesenchymal stem cells, providing the organism with radionuclides. 89 Zr-labeled umbilical cord mesenchymal stem cell preparation; through ingestion 89 Zr-labeled umbilical cord mesenchymal stem cells were detected and traced using positron emission tomography (PET).

[0025] Preferably, by analyzing PET-CT images, the differences in uptake and retention of umbilical cord mesenchymal stem cells in the target area of ​​diseased skin and non-target organs are quantitatively assessed through image analysis and quantification, and the pharmacokinetic distribution curves in vivo are plotted. The non-target organs are selected from the lung, liver, and spleen.

[0026] Preferably, the method is characterized by the following specific method:

[0027] S1 cell preparation: Take umbilical cord mesenchymal stem cell injection solution, centrifuge at 2500 rpm / min for 5 min, discard the supernatant and resuspend in PBS, centrifuge again and resuspend in PBS, repeat twice, and use 2 mL PBS for resuscitation.

[0028] S2 cell radionuclide labeling: oxalic acid was collected. 89 Zr solution, at a rate of mCi 89Zr was added to 5 μL of 5 mg / mL oxine solution, and the reaction was carried out at room temperature for 15 min; 10 μCi of [unspecified ingredient] was added per 10^6 cells. 89 Zr-oxine was incubated at room temperature for 15 min. After incubation, the mixture was centrifuged at 2500 rpm for 5 min and washed three times with PBS.

[0029] S3 Injection and Detection: The test substance is injected into the body; PET images and standard uptake values ​​at different time points are monitored and plotted.

[0030] Preferably, the preparation in step S2 89 Before Zr-oxine, pH adjustment is also included, with HEPES buffer solution (0.1 mol / L) and Na2CO3 solution (1 mol / L) used to adjust the pH to 7.

[0031] Preferably, the umbilical cord mesenchymal stem cell injection solution is a fresh cell preparation, not a frozen cell, and does not contain DMSO.

[0032] Preferably, the organism is a mammal, including patients with systemic sclerosis and model animals.

[0033] As can be seen from the above technical solutions, the technical solutions of the present invention provide the following beneficial effects:

[0034] The core innovation of this invention lies in utilizing... 89 Zr-labeled umbilical cord mesenchymal stem cells were used for the first time to discover and demonstrate their specific homing to skin fibrosis lesions in systemic sclerosis after intravenous infusion. Homing of skin fibrosis tissue was observed in both animal models and clinical patients. (The text also mentions using radionuclides.) 89 Zr-labeled umbilical cord mesenchymal stem cells (UMSCs) are used for pharmacokinetic tracing in sclerosis, overcoming the limitations of existing technologies in effectively assessing the targeting of UMSCs to skin tissue. This method enables real-time, non-invasive, and quantitative monitoring of the dynamic behavior of mesenchymal stem cells in animal models and patients, providing crucial support for precise cell-based drug delivery and efficacy evaluation. Therefore, using radionuclides... 89 Zr-labeled umbilical cord mesenchymal stem cells can be used to prepare pharmacokinetic tracers for systemic sclerosis.

[0035] On the one hand, it achieved intuitive verification of targeted homing, directly demonstrating for the first time through in vivo imaging that intravenously infused umbilical cord mesenchymal stem cells can specifically hom to skin fibrosis lesions in systemic sclerosis, breaking through the technical bottleneck of lacking direct targeted evidence in this field for a long time; on the other hand, it revealed the dynamic biological behavior of stem cells in systemic sclerosis, which not only serves treatment monitoring but also provides an important tool for basic research, helping to deepen the understanding of the migration patterns and mechanisms of action of mesenchymal stem cells in the microenvironment of systemic sclerosis. Attached Figure Description

[0036] Figure 1 Results of radiochemical purity (left) and cell viability (right) assays for labeled cells.

[0037] Figure 2 mice in the blank control group and SSc model group were injected via tail vein. 89 Micro PET / CT scan MIP image after Zr-RY_SW01

[0038] Figure 3 SSc model group (n=5) received tail vein injection. 89 Biodistribution of organs at different time points after Zr-RY_SW01

[0039] Figure 4 SSc model group and blank control group (n=5) were injected via tail vein. 89 Skin biodistribution results at different time points after Zr-RY_SW01

[0040] Figure 5 mice in the blank control group and SSc model group (n=5) were injected via tail vein. 89 Curve of blood radioactive uptake over time after Zr-RY_SW01

[0041] Figure 6 SUVmean-time curves of various tissues and organs of the subjects

[0042] Figure 7 Whole blood standardized intake (SUV) of subjects - time distribution plot

[0043] Figure 8 Comparison of facial skin lesions from different patients

[0044] Figure 9 Comparison of skin lesions on the hands of different patients

[0045] Figure 10 Comparison of skin lesions on the legs of different patients

[0046] Specific experimental methods

[0047] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and cannot be used to limit the protection scope of the present invention.

[0048] Definition:

[0049] PET positron emission tomography scanner

[0050] PMOD medical analysis software

[0051] %ID / g percentage injection dose rate per gram of tissue

[0052] SUV standardized uptake value

[0053] Activity meter An instrument for measuring the activity of radionuclides

[0054] μCi microcurie, the former unit of radioactivity

[0055] ROI refers to the term "region of interest" in image processing

[0056] RCP radiochemical purity

[0057] SUV standardized uptake value

[0058] 89 Zr zirconium-89

[0059] Main materials and reagents:

[0060] RY_SW01 cell injection: provided by Jiangsu Ruiyuan Biotechnology Co., Ltd.

[0061] Oxine: purchased from sigma Aldrich

[0062] 89 89 Zr-RY_SW01: 89 Zr-labeled umbilical cord mesenchymal stem cells

[0063] 150 female BALB / c mice, 5 weeks old, purchased from Hangzhou Ziyuan Laboratory Animal Technology Co., Ltd., with the animal production license number SCXK (Zhe) 2024-0004. <G

[0064] Example 1 Biological labeling and differentiation

[0065] 1) Hypochlorous acid mouse tissue distribution experiment

[0066] ​One hundred and fifty healthy female BALB / c mice aged five weeks were acclimatized for one week under natural light, free access to water and food, and an indoor temperature of 20-26°C and a relative humidity of 40-60% before scleroderma modeling was established.

[0067] Model establishment: A total of 52 blank control mice and 52 SSc model mice are required for the experiment. To ensure the success rate of the model, 150 mice were prepared for the establishment of the blank control group and the SSc model group, with 52 mice for each model.

[0068] The blank control group mice were established as follows: normal mice were subcutaneously injected with 300 μL of physiological saline in their backs for 5 days a week (Monday to Friday) for 6 consecutive weeks. The SSc model group mice were established as follows: normal mice were subcutaneously injected with 300 μL of HOCl in their backs for 5 days a week for 6 consecutive weeks. Three weeks after the HOCl injection, the model was tested. The SSc model was considered successfully established after confirmation of thickened skin and pulmonary fibrosis in the mice.

[0069] After successful model establishment, patients were randomly assigned to two groups for drug administration: the blank control group and the SSc model group were both given [treatment / treatment]. 89 Zr-labeled RY_SW01 cell injection; in the efficacy test, mice in the blank group and SSc model group were given excipient solvent, and the day of administration was recorded as D1.

[0070] The specific groups are as follows:

[0071]

[0072] 2) Human tissue distribution experiment

[0073] This study used 2.0 × 10 6 For dose studies of cells / kg, patients with systemic sclerosis aged ≥18 years and ≤75 years must be enrolled and meet all inclusion criteria and no exclusion criteria.

[0074]

[0075] Example 2 Cell Preparation

[0076] Take RY_SW01 cell injection solution (i.e., umbilical cord mesenchymal stem cell injection solution).

[0077] Use sterile scissors to cut open the seal and transfer the contents into 50 mL sterile centrifuge tubes;

[0078] Centrifuge at 2500 rpm / min for 5 min, discard the supernatant and resuspend in PBS. Repeat the process twice, using 2 mL of PBS to resuspend the cells.

[0079] Example 3 Cell Markers

[0080] Take oxalic acid 89 The Zr solution was adjusted to pH 7 using 9 times the volume of HEPES buffer solution (0.1 mol / L) and 0.6 times the volume of Na2CO3 solution (1 mol / L).

[0081] Oxalic acid with adjusted pH 89 Zr solution was mixed with 5 μL of 5 mg / mL oxine solution at a concentration of 1 mCi, and reacted at room temperature for 15 min to prepare the solution. 89 Zr-oxine;

[0082] Add 10 μCi per 10^6 cells 89 Zr-oxine was incubated at room temperature for 15 min.

[0083] After incubation, centrifuge at 2500 rpm for 5 minutes.

[0084] Wash three times with PBS to remove unbound cells. 89 Zr-oxine and free 89 Zr can be obtained 89 Zr-labeled umbilical cord mesenchymal stem cells ([ 89 Zr]-Oxine- RY_SW01).

[0085] Each batch tested showed a radiochemical purity of no less than 90%; an average cell viability of no less than 70.0%; and a retention rate of no less than 80%. See details. Figure 1 .

[0086] Example 4 Mouse Experiment

[0087] Tail vein injection 89 Zr-RY_SW01 cell injection solution 200 μL (0.125×10⁻⁶) 6 cells, 0.25×10 6 cells, 0.5×10 6 After administration of the drug (cells), a whole-body Micro PET / CT scan was performed. The imaging time points were 1 h, 3 h, 6 h, 12 h, D1, D2, and D3 after drug administration. In the blank control group of dose group 3, the scans were extended at D5 and D7.

[0088] After the Micro PET / CT scan, image reconstruction was performed. PMOD software (version 4.3) was used to process the images and data, and the region of interest (ROI) was delineated. The radioactivity concentration of the ROI was obtained, and the percentage of tissue radioactive uptake (%ID / g) relative to the injected dose was calculated. %ID / g = Radioactivity concentration of ROI / Total total radioactive uptake during the scan * 100.

[0089] Mice in dose group 2 (blank control group) and SSc model treatment group were injected via tail vein 89 Zr-RY_SW01 cells were euthanized at 3 h, 6 h, 24 h, 48 h, and 72 h after radioactive uptake, and tissue distribution studies were conducted. Blood, brain, heart, liver, spleen, lung, kidney, stomach, small intestine, large intestine, thigh muscle, femur, joints, skin, and lymph nodes were collected, weighed, and gamma counts were performed. The %ID / g of each tissue and organ was calculated. The %ID / g of radioactive uptake in each tissue was calculated using the formula: %ID / g = tissue radioactivity count (CPM) / total systemic radioactivity count (CPM) × 100 / tissue weight (g).

[0090] like Figures 2-4 As shown, mice were injected via the tail vein. 89 Following Zr-RY_SW01 administration, the time-varying trends of radioactive uptake in various organs were largely similar in the blank control group and the SSc model treatment group. In the lungs and lymph nodes, radioactive uptake reached its peak 1 hour after administration and then gradually decreased. In the kidneys and spleen, radioactive uptake gradually increased, reaching its maximum at 24 hours and then stabilizing. In the liver, radioactive uptake gradually increased, reaching its maximum at 6 hours and then stabilizing. In the blank control group, skin radioactive uptake gradually increased, reaching its maximum at 6 hours and then gradually decreased, while in the SSc model treatment group, skin radioactive uptake gradually increased, reaching its maximum at 48 hours and then gradually decreased. Except for 3 hours, the skin radioactive uptake in the SSc model group was significantly higher than that in the blank control group (p < 0.001), indicating that umbilical cord mesenchymal stem cells could significantly home to diseased skin tissue.

[0091] In addition, the drug-time curves after drug administration in the blank control group and the SSc model treatment group mice are as follows: Figure 5 As shown, 3 h, 6 h, and 48 h after drug administration, 89 There was no significant difference in peripheral blood uptake of Zr-RY_SW01 between the SSc model treatment group and the blank control group (p > 0.05); 72 h after administration, 89 The peripheral blood uptake of Zr-RY_SW01 in the SSc model treatment group mice was 0.24±0.03%ID / g, which was significantly lower than that in the blank control group mice (0.42±0.05%ID / g) (p<0.001).

[0092] Overall, intravenous injection 89 Following Zr-RY_SW01 administration, mice were injected via the tail vein. 89 After Zr-RY_SW01, the radioactive material was mainly concentrated in the lungs, then distributed to the liver and other tissues, and was able to significantly hom to the diseased skin tissue. Furthermore, the radioactivity in the peripheral blood decreased rapidly without significant accumulation.

[0093] Example 5 [ 89 Zr]-Oxine-RY_SW01 is injected into patients with scleroderma.

[0094] Intravenous injection of 2.0 × 10 6 This study, using cells / kg, enrolled four patients aged ≥18 years and ≤75 years with systemic sclerosis, who met all inclusion criteria and did not meet any exclusion criteria. Six PET image sampling points were set up for this trial: within 15 minutes after infusion, 4 h ± 1 h, D1 (24 ± 2 h), D3 (72 ± 2 h), D5 (120 ± 2 h), and D7 (168 ± 2 h).

[0095] After the Micro PET / CT scan, image reconstruction was performed. PMOD software (version 4.3) was used to process the images and data, and the region of interest (ROI) was delineated. The radioactivity concentration of the ROI was obtained, and the percentage of tissue radioactive uptake (%ID / g) relative to the injected dose was calculated. %ID / g = Radioactivity concentration of ROI / Total total radioactive uptake during the scan * 100.

[0096] A descriptive summary of PET image acquisition data was provided within 15 minutes of the end of infusion, at 4 h ± 1 h, on day 1 (24 ± 2 h), day 3 (72 ± 2 h), day 5 (120 ± 2 h), and day 7 (168 ± 2 h). The summary includes the standardized uptake value (SUV) measurements of important organs or tissues at each time point, the blood uptake rate (%ID), the uptake rate (%ID) of each organ or tissue at each time point, the absorbed dose of each organ or tissue, and the effective systemic dose for each individual. Time-radioactivity curves (TACs) for each tissue and organ will also be plotted, and the distribution and changes of transplanted cells in different tissues or organs at different time points will be described.

[0097] like Figure 6 , Figure 8-10 As shown, 89Zr-Oxine-RY_SW01 cells initially accumulated in the lungs, subsequently migrating to highly perfused organs such as the liver and spleen. The signal intensity in the lungs decreased rapidly, and no significant persistent pulmonary accumulation was observed during the 7-day observation period. Simultaneously, with long-term follow-up, the patients' skin softened rapidly, and the mRSS skin score significantly decreased, suggesting a significant therapeutic effect of umbilical cord mesenchymal stem cells.

[0098] like Figure 7 As shown, 89 Zr-Oxine-RY_SW01 cell injection in blood T 1 / 2 The duration was 166.18 ± 88.82 h, T max The duration was 1.00 ± 1.15 h, C max For SUVs, the AUC is 3.96±0.71. 0-t For 295.22 SUV*h, the T in the lungs 1 / 2 The duration was 74.52 ± 12.65 h, T max The duration was 1.00 ± 2.00 h, C max For 11.64±1.32 SUV, AUC 0-t The value is 463.63±117.69 SUV*h.

[0099] Consistent with animal experiment results, 89 Zr-Oxine-RY_SW01 cells can actively home to diseased lung lesions, skin tissue from finger lesions, and skin tissue from facial lesions in vivo, and the degree of enrichment is positively correlated with the severity of the lesions. Radiation levels in peripheral blood decrease rapidly, with no significant accumulation.

[0100] In summary, this invention provides a method using radioactive nuclides 89 A method for using Zr-labeled umbilical cord mesenchymal stem cells in the preparation of pharmacokinetic tracers for systemic sclerosis. This method has been validated in both animals and humans for the effectiveness of the labeled radionuclide. 89 Once in vivo, Zr-Oxine-RY_SW01 cells rapidly distribute from the bloodstream to various organs and home to lesion sites, especially skin lesions, thereby exerting a therapeutic effect. This method establishes a relationship between the dynamic distribution of stem cells in vivo and their therapeutic efficacy, enabling the visualization and evaluation of the in vivo distribution and efficacy of stem cell therapy, which has significant clinical translational value.

Claims

1. Using radioactive nuclides 89 Application of Zr-labeled umbilical cord mesenchymal stem cells in the preparation of pharmacokinetic tracers for systemic sclerosis.

2. The application according to claim 1, characterized in that, The umbilical cord mesenchymal stem cells mentioned are a preparation derived from fresh umbilical cord mesenchymal stem cells and do not contain DMSO.

3. The application according to any one of claims 1-2, characterized in that, The radioactive nuclide 89 Zr-labeled umbilical cord mesenchymal stem cells had a radiochemical purity of ≥90%, cell viability of ≥90%, and an in vitro 24-hour retention rate of ≥85%.

4. The application according to any one of claims 1-3, characterized in that, The aforementioned pharmacokinetic tracer for systemic sclerosis is used to evaluate the in vivo efficacy and distribution kinetics of umbilical cord mesenchymal stem cell therapy for systemic sclerosis, and to observe the homing of mesenchymal stem cells to diseased skin tissue in order to determine its therapeutic effect.

5. Using radioactive nuclides 89 A method for pharmacokinetic tracing of systemic sclerosis using Zr-labeled umbilical cord mesenchymal stem cells, characterized in that... Providing radionuclides to organisms 89 Zr-labeled umbilical cord mesenchymal stem cell preparation; through ingestion 89 Zr-labeled umbilical cord mesenchymal stem cells were detected and traced using positron emission tomography (PET).

6. The method according to claim 5, characterized in that, By analyzing PET-CT images, the differences in uptake and retention of umbilical cord mesenchymal stem cells in the target area of ​​diseased skin and non-target organs were quantitatively assessed, and their pharmacokinetic distribution curves in vivo were plotted. The non-target organs were selected from the lung, liver, and spleen.

7. The method according to claim 5, characterized in that, The specific method is as follows: S1 cell preparation: Take umbilical cord mesenchymal stem cell injection solution, centrifuge at 2500 rpm / min for 5 min, discard the supernatant and resuspend in PBS, centrifuge again and resuspend in PBS, repeat twice, and use 2 mL PBS for resuscitation. S2 cell radionuclide labeling: oxalic acid was collected. 89 Zr solution, at a rate of mCi 89 Zr was added to 5 μL of 5 mg / mL oxine solution, and the reaction was carried out at room temperature for 15 min; 10 μCi of [unspecified ingredient] was added per 10^6 cells. 89 Zr-oxine was incubated at room temperature for 15 min. After incubation, the mixture was centrifuged at 2500 rpm for 5 min and washed three times with PBS. S3 Injection and Detection: The test substance is injected into the body; PET images and standard uptake values ​​at different time points are monitored and plotted.

8. The method of using radioactive nuclides as described in claim 7 89 A method for tracing the pharmacokinetics of Zr-labeled umbilical cord mesenchymal stem cells in systemic sclerosis, characterized in that... Preparation in step S2 89 Before Zr-oxine, pH adjustment is also included, with HEPES buffer solution and Na2CO3 solution used to adjust the pH to 7.

9. The method according to claim 7, characterized in that, The umbilical cord mesenchymal stem cell injection solution is a fresh cell preparation, not a frozen cell, and does not contain DMSO.

10. The method according to claim 7, characterized in that, The organisms referred to are mammals, including patients with systemic sclerosis and model animals.

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