Desmin- and vimentin-mediated hepatic stellate cell-targeting radiotracer ^99mTc-GlcNAc-PEI for liver fibrosis imaging with SPECT

Abstract

Extracellular matrix (ECM) accumulation in liver fibrosis is caused by the activation of hepatic stellate cells (HSCs). The goal of this study was to develop a 99mTc-labeled N-acetylglucosamine (GlcNAc) that specifically interacts with desmin and vimentin expressed on activated HSCs to monitor the progression and prognosis of liver fibrosis using single-photon emission computed tomography (SPECT) imaging.Methods: GlcNAc-conjugated polyethylenimine (PEI) was first prepared and radiolabeled with 99mTc. Noninvasive SPECT imaging with 99mTc-GlcNAc-PEI was used to assess liver fibrosis in a carbon tetrachloride (CCl4) mouse model. The liver uptake value (LUV) of 99mTc-GlcNAc-PEI was measured by drawing the region of interest (ROI) of the whole liver as previously suggested. The LUV of the CCl4 groups was compared with that of the olive oil group. Next, we estimated the correlation between the results of SPECT imaging and physiological indexes. After treatment with clodronate liposome, the LUV of 99mTc-GlcNAc-PEI in fibrotic mice was compared with that in control mice.Results: 99mTc-GlcNAc-PEI is a hydrophilic compound with high radiochemical purity (>98%) and good stability. It could specifically target desmin and vimentin on the surface of activated HSCs with high affinity (the Kd values were 53.75 ± 9.50 nM and 20.98 ± 3.56 nM, respectively). The LUV of 99mTc-GlcNAc-PEI was significantly different between the CCl4 and control groups as early as 4 weeks of CCl4 administration (3.30 ± 0.160 vs 2.34 ± 0.114%/cc; P ˂ 0.05). There was a strong correlation between the LUV and Sirius Red quantification (R = 0.92, P ˂ 0.001). Compared with control, clodronate liposome treatment reduced the LUV of 99mTc-GlcNAc-PEI (4.62 ± 0.352 vs 2.133 ± 0.414%/cc; P ˂ 0.05).Conclusion: 99mTc-GlcNAc-PEI SPECT/CT was useful in assessing liver fibrosis and monitoring the treatment response.

Kupffer Cells: Important Participant of Hepatic Alveolar Echinococcosis

“…As shown in Figure 2D, the mRNA level of TGF-β1 in the liver lesions was significantly elevated in the close group than that in the distance group (P < 0.05). α-SMA, Desmin are the surface markers of HSCs activation (Ding et al, 2014;Zhang et al, 2018;Inzaugarat et al, 2019), mainly express in the cytoplasm of the vascular wall or in the cytoplasm of activated HSCs. We performed IHC and qRT-PCR assay to assess the protein and gene levels, respectively.…”

Molecular Probes for Imaging Fibrosis and Fibrogenesis

“…The expression of desmin and vimentin is upregulated in activated HSCs . A fluorescent probe and, more recently, a SPECT probe called 99m Tc‐GlcNAc‐PEI (Figure ) were developed by using polymers containing N ‐acetylglucosamine (GlNAc) that demonstrated high affinity for desmin and vimentin. The radiotracer 99m Tc‐GlcNAc‐PEI could detect liver fibrosis 4 weeks after CCl 4 treatment in a mouse model.…”

Development of a Gene Delivery System of Oligonucleotides for Fibroses by Targeting Cell-Surface Vimentin-Expressing Cells with N-Acetylglucosamine-Bearing Polymer-Conjugated Polyethyleneimine

“…The size of the AC-GlcNAc-conjugated PEI complex (1:10) was approximately 100 nm, and this size might be optimal for cellular uptake. These complexes were taken up into the cytoplasm through cell-surface vimentin-mediated endocytosis and were then probably incorporated into endosomes and lysosomes [ 21 , 22 , 23 ]. These complexes (i.e., the conjugation of AC-GlcNAc to PEI and the self-assembly of PEI) were formed by disulfide bonds.…”

“…Namely, the type III intermediate filament proteins vimentin, desmin, glial fibrillary acidic protein, and peripherin are expressed on the surface of various cells and possess N-acetylglucosamine (GlcNAc)-binding activity via GlcNAc-bearing polymers [ 14 , 15 , 16 , 17 , 18 , 19 ]. Moreover, vimentin and desmin are highly expressed on myofibroblasts and activated stellate cells in various lesion sites [ 20 , 21 ], and it is possible to target activated stellate cells in liver fibrosis with bio-imaging systems that utilize GlcNAc-conjugated polyethyleneimine (GlcNAc-PEI) and small interfering (siRNA) delivery systems [ 22 , 23 ]. Namely, GlcNAc-PEI accumulates in fibrotic but not normal liver tissues, and it specifically interacts with activated stellate cells that express desmin, suggesting that desmin and vimentin can be highly expressed on the cell surface of myofibroblasts and activated stellate cells in fibrotic tissues.…”

“…To date, GlcNAc-PEIs have been produced by randomly conjugating GlcNAc to PEI [ 22 , 23 , 24 ], thus making it difficult to reproduce and precisely control the degree of GlcNAc-conjugation. Therefore, it is important to develop GlcNAc-bearing polymers with high affinity to cell surface vimentin and desmin, and the production of gene carriers that are conjugated to these GlcNAc-bearing polymers might be advantageous to target myofibroblasts and activated stellate cells.…”