Liver-targeted gene delivery through retrograde intrabiliary infusion

Vascular endothelial growth factor protein and gene delivery by novel nanomaterials for promoting liver regeneration after partial hepatectomy

Partial hepatectomy (PH) can lead to severe complications, including liver failure, due to the low regenerative capacity of the remaining liver, especially after extensive hepatectomy. Liver sinusoidal endothelial cells (LSECs), whose proliferation occurs more slowly and later than hepatocytes after PH, compose the lining of the hepatic sinusoids, which are the smallest blood vessels in the liver. Vascular endothelial growth factor (VEGF), secreted by hepatocytes, promotes LSEC proliferation. Supplementation of exogenous VEGF after hepatectomy also increases the number of LSECs in the remaining liver, thus promoting the reestablishment of the hepatic sinusoids and accelerating liver regeneration. At present, some shortcomings exist in the methods of supplementing exogenous VEGF, such as a low drug concentration in the liver and the reaching of other organs. More-over, VEGF should be administered multiple times and in large doses because of its short half-life. This review summarized the most recent findings on liver regeneration and new strategies for the localized delivery VEGF in the liver.

Hydrodynamic Delivery: Characteristics, Applications, and Technological Advances

The principle of hydrodynamic delivery was initially used to develop a method for the delivery of plasmids into mouse hepatocytes through tail vein injection and has been expanded for use in the delivery of various biologically active materials to cells in various organs in a variety of animal species through systemic or local injection, resulting in significant advances in new applications and technological development. The development of regional hydrodynamic delivery directly supports successful gene delivery in large animals, including humans. This review summarizes the fundamentals of hydrodynamic delivery and the progress that has been made in its application. Recent progress in this field offers tantalizing prospects for the development of a new generation of technologies for broader application of hydrodynamic delivery.

Delivery of non-viral naked DNA vectors to liver in small weaned pigs by hydrodynamic retrograde intrabiliary injection

Hepatic gene therapy by delivering non-integrating therapeutic vectors in newborns remains challenging due to the risk of dilution and loss of efficacy in the growing liver. Previously we reported on hepatocyte transfection in piglets by intraportal injection of naked DNA vectors. Here, we established delivery of naked DNA vectors to target periportal hepatocytes in weaned pigs by hydrodynamic retrograde intrabiliary injection (HRII). The surgical procedure involved laparotomy and transient isolation of the liver. For vector delivery, a catheter was placed within the common bile duct by enterotomy. Under optimal conditions, no histological abnormalities were observed in liver tissue upon pressurized injections. The transfection of hepatocytes in all tested liver samples was observed with vectors expressing luciferase from a liver-specific promoter. However, vector copy number and luciferase expression were low compared to hydrodynamic intraportal injection. A 10-fold higher number of vector genomes and luciferase expression was observed in pigs using a non-integrating naked DNA vector with the potential for replication. In summary, the HRII application was less efficient (i.e., lower luciferase activity and vector copy numbers) than the intraportal delivery method but was significantly less distressful for the piglets and has the potential for injection (or re-injection) of vector DNA by endoscopic retrograde cholangiopancreatography.

Parameters of biliary hydrodynamic injection during endoscopic retrograde cholangio-pancreatography in pigs for applications in gene delivery

The biliary system is routinely accessed for clinical purposes via endoscopic retrograde cholangiopancreatography (ERCP). We previously pioneered ERCP-mediated hydrodynamic injection in large animal models as an innovative gene delivery approach for monogenic liver diseases. However, the procedure poses potential safety concerns related mainly to liver or biliary tree injury. Here, we sought to further define biliary hydrodynamic injection parameters that are well-tolerated in a human-sized animal model. ERCP was performed in pigs, and hydrodynamic injection carried out using a novel protocol to reduce duct wall stress. Each pig was subjected to multiple repeated injections to expedite testing and judge tolerability. Different injection parameters (volume, flow rate) and injection port diameters were tested. Vital signs were monitored throughout the procedure, and liver enzyme panels were collected pre- and post-procedure. Pigs tolerated repeated biliary hydrodynamic injections with only occasional, mild, isolated elevation in aspartate aminotransferase (AST), which returned to normal levels within one day post-injection. All other liver tests remained unchanged. No upper limit of volume tolerance was reached, which suggests the biliary tree can readily transmit fluid into the vascular space. Flow rates up to 10 mL/sec were also tolerated with minimal disturbance to vital signs and no anatomic rupture of bile ducts. Measured intrabiliary pressure was up to 150 mmHg, and fluid-filled vesicles were induced in liver histology at high flow rates, mimicking the changes in histology observed in mouse liver after hydrodynamic tail vein injection. Overall, our investigations in a human-sized pig liver using standard clinical equipment suggest that ERCP-guided hydrodynamic injection will be safely tolerated in patients. Future investigations will interrogate if higher flow rates and pressure mediate higher DNA delivery efficiencies.

The Effect of Lecithins Coupled Decorin Nanoliposomes on Treatment of Carbon Tetrachloride-Induced Liver Fibrosis

This study aimed to investigate the effect of bile duct-targeting lecithins- (PC-) coupled decorin (DCN) (PC-DCN) nanoliposomes against liver fibrosis in vitro and in vivo. We prepared PC-DCN nanoliposomes by using rat astrocytes, HSC-T6, to verify the antifibrosis effect of PC-DCN in vitro. First, we established a rat model of carbon tetrachloride-induced fibrosis. PC-DCN nanoliposomes were then injected into fibrotic rats via the portal vein or bile duct. The EdU assay was performed to analyze cell proliferation. Immunofluorescence staining was used to detect α-smooth muscle actin (α-SMA) expression. Western blot was performed to examine the expression of α-SMA, collagen type I alpha 1 (COL1A1), and transforming growth factor-β (TGF-β) protein. The levels of aspartate transaminase (AST), alanine transaminase (ALT), and total bilirubin (TBIL) were examined by enzyme-linked immunosorbent assay (ELISA) analysis. Hematoxylin and eosin (H&E) staining and Masson trichrome staining were used to determine liver tissue lesions and liver fibrosis. Compared with TGF-β group, PC-DCN treatment could significantly reduce cell proliferation. Western blot analysis indicated that the expression of α-SMA, COL1A1, and TGF-β was downregulated after treatment with PC-DCN in vitro and in vivo. Immunofluorescence staining confirmed that α-SMA expression was reduced by PC-DCN. Furthermore, H&E staining and Masson trichrome staining showed that the administration of PC-DCN nanoliposomes via the bile duct could reduce the extent of liver fibrosis. PCR analysis showed that PC-DCN administration could reduce proinflammatory cytokines IL-6, TNF-α, and IL-1β expression via the bile duct. The administration of PC-DCN nanoliposomes also significantly downregulated liver function indicators ALT, AST, and TBIL. The results of our study indicated that PC-DCN could effectively reduce the extent of liver fibrosis.

Hepatic gene transfer of human aquaporin-1 improves bile salt secretory failure in rats with estrogen-induced cholestasis

The adenoviral gene transfer of human aquaporin-1 (hAQP1) water channels to the liver of 17α-ethinylestradiol-induced cholestatic rats improves bile flow, in part by enhancing canalicular hAQP1-mediated osmotic water secretion. To gain insight into the mechanisms of 17α-ethinylestradiol cholestasis improvement, we studied the biliary output of bile salts (BS) and the functional expression of the canalicular BS export pump (BSEP; ABCB11). Adenovector encoding hAQP1 (AdhAQP1) or control vector was administered by retrograde intrabiliary infusion. AdhAQP1-transduced cholestatic rats increased the biliary output of major endogenous BS (50%-80%, P < 0.05) as well as that of taurocholate administered in choleretic or trace radiolabel amounts (around 60%, P < 0.05). Moreover, liver transduction with AdhAQP1 normalized serum BS levels, otherwise markedly elevated in cholestatic animals. AdhAQP1 treatment was unable to improve BSEP protein expression in cholestasis; however, its transport activity, assessed by adenosine triphosphate-dependent taurocholate transport in canalicular membrane vesicles, was induced by 90% (P < 0.05). AdhAQP1 administration in noncholestatic rats induced no significant changes in either biliary BS output or BSEP activity. Canalicular BSEP, mostly present in raft (high cholesterol) microdomains in control rats, was largely found in nonraft (low cholesterol) microdomains in cholestasis. Considering that BSEP activity directly depends on canalicular membrane cholesterol content, decreased BSEP presence in rafts may contribute to BSEP activity decline in 17α-ethinylestradiol cholestasis. In AdhAQP1-transduced cholestatic rats, BSEP showed a canalicular microdomain distribution similar to that of control rats, which provides an explanation for the improved BSEP activity.

CONCLUSION

Hepatocyte canalicular expression of hAQP1 through adenoviral gene transfer promotes biliary BS output by modulating BSEP activity in estrogen-induced cholestasis, a novel finding that might help us to better understand and treat cholestatic disorders. (Hepatology 2016;64:535-548).