^99mTc-3PRGD2 scintigraphy to stage liver fibrosis and evaluate reversal after fibrotic stimulus withdrawn

Scintigraphy using 99mTc-3PRGD2 targeting integrin αvβ3 could assess activation of hepatic stellate cells (HSCs). Liver fibrogenesis is intimately associated with activation of HSCs, and the fibrolytic process is accompanied by the reduction of the activated HSCs. In this study, we aimed to evaluate the feasibility of this method to assess the severity of liver fibrosis and the reversal after the fibrotic stimulus withdrawal.

Liver fibrosis of different stages was induced by thioacetamide (TAA) injection for 2, 4 and 6 weeks (n = 6 for each time point). Another 6 rats with 8-week TAA administration (the 8-week group) and 6 rats which were injected with TAA for 6 weeks, and then withdrawn of TAA for 2 weeks (spontaneous recovery rats, SRR) were designed. The ratios of radioactivity detected in the liver vs. the heart at 30 min post-injection of ^99mTc-3PRGD2 (L/H30_min), the collagen proportionate area (CPA), the protein and mRNA levels of integrin α_v, integrin β₃ were analyzed and compared among groups.

The Ishak stage scores of the livers in the control and 2, 4, 6-week groups increased when the TAA administration period was extended. L/H30_min increased with the upgrading of liver fibrosis and the differences between each pair of groups were statistically significant (p 30 min in the 8-week group was similar to that in the 6-week group (p > 0.05), but was significantly higher than that in the SRR group (p = 0.005).

Scintigraphy using ^99mTc-3PRGD2 may provide a non-invasive method for grading liver fibrosis and assessing liver fibrosis reversal.