Targeted Contrast Agent VEGF_125-136-Gd Experimental Study On Magnetic Resonance Imaging Of Tumor-bearing Nude Mice In Vivo

Objective:The targeted magnetic resonance contrast agent VEGF_125-136-Gd was prepared through making Gd,magnetic resonance positive imaging agent,labeled polypeptide?VEGF125-136?for targeting VEGFR-2 on the surface of the HEP G2hepatoma cells.Evaluate the efficiency targeted tumor and metabolism of VEGF_125-136-Gd through magnetic resonance imaging about transplanted HEP G2tumor nude mice in vivo.Methods:?1?The preparation of magnetic resonance contrast agent:The targeted magnetic resonance contrast agent VEGF_125-136-Gd and the non-targeted magnetic resonance contrast agent NTSP-Gd were prepared through labeling Gd to the targeted polypeptide VEGF125-136 and the non-targeted polypeptide NTSP,and identified their physical and chemical properties by HPLC purification and chemical mass spectrometry.?2?Histopathological and immunohistochemical studies of HEP G2hepatoma bearing nude mice:observed the tissue and cell characteristics of each region of interest,and evaluated the intensity of VEGFR-2 expression and semi quantitative analysis.?3?Preliminary assessment of maximal tolerance of HEP G2hepatoma bearing nude mice in vivo:12 HEP G2 hepatoma bearing nude mice were randomly divided into 3 groups,4 in each group.Each group was given a dose.The toxic reaction and death of the tumor bearing nude mice after the drug were observed.?4?Magnetic resonance imaging experiment in HEP G2 hepatoma bearing nude mice:10 HEP G2 hepatoma bearing nude mice were randomly divided into two groups,5 in each group.The experimental group used VEGF_125-136-Gd and the control group used NTSP-Gd though caudal vein injection,measured the T1WI signal intensity of the region of interest at discontinuous multiple time points,and made the time signal-to-noise ratio?T-SNR?curve.?5?Statistical analysis of data:The signal intensity data of the region of interest was the repeated measurement data through the discontinuous multi time points image information acquisition method.Analyzed the difference of signal intensity of different the region of interest within the group or between the groups at the same measurement time point through the t-test methods of independent samples.The above statistical analysis showed that the difference was statistically significant in P<0.05.Results:?1?HPLC:The target contrast agent VEGF125-136-Gd and the non-target contrast agent NTSP-Gd all showed"single peak",and the purity was more than 98%.Chemical mass spectrometry tests showed that the coupling of two magnetic resonance contrast agents was successful.?2?Histopathological and immunohistochemical studies of HEP G2 hepatoma bearing nude mice showed that the tumor was a typical malignant tumor with histological features,but no metastasis was found in the liver,kidney,muscle and spleen tissues.The expression of VEGFR-2 was different in different tissues,transplanted tumor?12 points?>liver?3points?>kidney?2 points?=muscle?2 points?>spleen?0 points?.?3?The maximum tolerance of the homemade targeting contrast agent VEGF127-133-Gd in HEP G2tumor bearing nude mice was 50 mg/kg.?4?The tumor area was significantly enhanced in the both group.The T-SNR curve of the tumor area was"double peak"?"5min peak"and"60min peak"?in the experimental group and"single peak"?"5min peak"?in the control group.The difference of SNR at the peak time point of"60min peak"was statistically significant between the experimental group and the control group in the tumor area?P<0.05?.The SNR of the tumor area and muscle area was statistically significant in the experimental group?P<0.05?.The area kidney was significantly enhanced in the both group.The T-SNR curve was"double peak"in the both group.The difference of SNR was not statistically significant between the both group in the kidney area?P>0.05?.The area muscle was slightly enhanced in the both group.The T-SNR curve was"single peak"in the both group.The difference of SNR was not statistically significant between the both group in the muscle area?P>0.05?.Conclusion:The homemade magnetic resonance targeted contrast agent,VEGF_125-136-Gd,was successfully coupled,and the specific imaging of VEGFR-2target of tumor cells was preliminarily achieved in vivo.The magnetic resonance targeted contrast agent was mainly metabolized by the kidney.