| Objective Knee MRI T1 mapping scans and intra chondral MMP-1 expression measurements were performed on sheep knee osteoarthritis(KOA)models with different degrees of osteoarthritis to investigate the correlation between T1 mapping values and intra chondral MMP-1 expression in sheep knee cartilage.Methods The sheep knee osteoarthritis model was established by selecting 15 Mongolian fine hair sheep(age 8-10 months,weight 20±3 kg),randomly divided into five groups of three animals each,labeled as group A,group B,group C,group D and group E.Group A was set as the control group,and the other four groups were the modeling groups with different degrees of damage.The other four groups were modeling groups with different degrees of injury,and papain solution(1.4 ml each time)was injected into the left knee joint of all modeling groups on the 1st,4th and 7th days of the experiment,respectively.The sheep in the control group were kept for one week and then underwent MRI scanning of the left knee;the sheep in the modeling group were kept normally after modeling and underwent MRI scanning of the left knee at 1 week for group B,at 3 weeks for group C,at 5 weeks for group D and at 7 weeks for group E.The scan sequences were conventional MRI sequences and quantitative MRI(T1mapping)scans,and the scan data were uploaded to Syngo Via VB10 B.After the T1 mapping fusion pseudo-color map was obtained,the cartilage of the medial femoral condyle and medial tibial plateau was divided into three areas: anterior,middle and posterior on the sagittal fusion pseudo-color map,and the thickest cartilage in the middle stress area was selected as the Area of interest(ROI)to measure the T1 mapping value,and each ROI was repeated three times to obtain the average value and recorded.After executing each group of sheep that completed MRI scanning and removing the knee joint for gross observation(morphology,color and glossiness)and recording,the specimens were then decalcified,dehydrated,embedded and cut into sections for immunohistochemical staining,and MMP-1expression was observed under a light microscope,and the positive expression rate of MMP-1in each group was measured using Image-Pro Plus 6.0 image processing software The positive expression rate of each group of MMP-1 was measured and recorded using Image-Pro Plus 6.0 image processing software,and this experiment was performed by measuring the average optical density(AOD)was used to reflect the positive expression rate of MMP-1.The data of T1 mapping and AOD values were uploaded to SPSS24.0 software for analysis,and the measurement data met normal distribution and chi-square using one-way ANOVA,and the comparison between groups was performed by LSD test,and P < 0.05 was statistically significant;Pearson correlation analysis was used to analyze whether there was correlation between cartilage T1 mapping values and cartilage MMP-1 expression.Results(1)The T1 mapping values of the cartilage of the medial femoral condyle were higher in all modeling groups than in the control group(P<0.05),and the T1 mapping values tended to increase gradually with the extension of the modeling time;when comparing the modeling groups,there was a statistical difference between the two groups except for groups C and D(P>0.05);(2)The T1 mapping values of the cartilage of the medial tibial plateau were higher in all modeling groups than in the control group(P<0.05);and the T1 mapping values tended to increase gradually with the extension of the modeling time.(2)The T1 mapping values of cartilage in the medial tibial plateau were higher in all modeling groups than in the control group(P<0.05),and the T1 mapping values tended to increase gradually as the modeling time increased;when comparing the modeling groups,there was a statistical difference between the two groups except for groups C and D(P>0.05).0.05);(3)the expression of soft MMP-1in the medial femoral condyle was higher in all modeling groups than in the control group(P<0.05),and the expression of MMP-1 showed a gradual increase with the prolongation of modeling time;the comparison between the two groups was statistically different(P<0.05);(4)the expression of MMP-1 in the cartilage of the medial tibial plateau was higher in all modeling groups than in the control group(P<0.05).(4)MMP-1 expression in the cartilage of the medial femoral condyle and medial tibial plateau was higher in all modeling groups than in the control group(P<0.05),and MMP-1 expression showed a trend of gradual increase as the modeling time was prolonged;the comparison between the modeling groups was statistically different(P<0.05);(5)T1 values of the cartilage of the medial femoral condyle and medial tibial plateau showed a trend of gradual increase as the modeling time was prolonged,and MMP-1 expression showed a trend of gradual increase,and the results of Pearson correlation analysis were The results of Pearson correlation analysis showed a linear positive correlation between the T1 value of medial femoral condyle and MMP-1 expression(AOD value)(R2=0.882,P<0.05),and a linear positive correlation between the T1 value of medial tibial plateau and MMP-1 expression(AOD value)(R2=0.944,P<0.05).Conclusion In OA cartilage degeneration,the T1 value is higher than normal and shows a trend of gradual increase with the prolongation of the modeling time,while the expression of MMP-1 in cartilage also shows a trend of gradual increase with the prolongation of the modeling time,and the T1 value and the expression of MMP-1 are positively correlated.The magnetic resonance T1 mapping sequence can reflect the pathophysiological process of cartilage in OA patients,quantitatively reflect the degree of cartilage damage,and possibly monitor the expression of MMP-1 in cartilage,which is expected to be a non-invasive index for the examination of MMP-1 expression in cartilage in the assessment of OA,and is important for the diagnosis of early OA and the follow-up after treatment. |
PDF Full Text Request