Evaluation of life cycle defective adenovirus mutants for production of adeno-associated virus vectors

AAV production in stable packaging cells requires expression of adenovirus 22/33K protein to allow episomal amplification of integrated rep/cap genes

Efficient manufacture of recombinant adeno-associated virus (rAAV) vectors for gene therapy remains challenging. Packaging cell lines containing stable integration of the AAV rep/cap genes have been explored, however rAAV production needs to be induced using wild-type adenoviruses to promote episomal amplification of the integrated rep/cap genes by mobilizing a cis-acting replication element (CARE). The adenovirus proteins responsible are not fully defined, and using adenovirus during rAAV manufacture leads to contamination of the rAAV preparation. 'TESSA' is a helper adenovirus with a self-repressing Major Late Promoter (MLP). Its helper functions enable efficient rAAV manufacture when the rep and cap genes are provided in trans but is unable to support rAAV production from stable packaging cells. Using rAAV-packaging cell line HeLaRC32, we show that expression of the adenovirus L4 22/33K unit is essential for rep/cap amplification but the proteins are titrated away by binding to replicating adenovirus genomes. siRNA-knockdown of the adenovirus DNA polymerase or the use of a thermosensitive TESSA mutant decreased adenovirus genome replication whilst maintaining MLP repression, thereby recovering rep/cap amplification and efficient rAAV manufacture. Our findings have direct implications for engineering more efficient adenovirus helpers and superior rAAV packaging/producer cells.

4-Octyl itaconate suppresses the osteogenic response in aortic valvular interstitial cells via the Nrf2 pathway and alleviates aortic stenosis in mice with direct wire injury

Calcific aortic valve disease (CAVD) is the most prevalent valvular heart disease in older individuals, but there is a lack of drug treatment. The cellular biological mechanisms of CAVD are still unclear. Oxidative stress and endoplasmic reticulum stress (ER stress) have been suggested to be involved in the progression of CAVD. Many studies have demonstrated that 4-octyl itaconate (OI) plays beneficial roles in limiting inflammation and oxidative injury. However, the potential role of OI in CAVD has not been thoroughly explored. Thus, we investigated OI-mediated modulation of ROS generation and endoplasmic reticulum stress to inhibit osteogenic differentiation in aortic valve interstitial cells (VICs). In our study, calcified aortic valves showed increased levels of ER stress and superoxide anion, as well as abnormal expression of Hmox1 and NQO1. In VICs, OI activated the Nrf2 signaling cascade and contributed to Nrf2 stabilization and nuclear translocation, thus augmenting the expression of genes downstream of Nrf2 (Hmox1 and NQO1). Moreover, OI ameliorated osteogenic medium (OM)-induced ROS production, mitochondrial ROS levels and the loss of mitochondrial membrane potential in VICs. Furthermore, OI attenuated the OM-induced upregulation of ER stress markers, osteogenic markers and calcium deposition, which were blocked by the Nrf2-specific inhibitor ML385. Interestingly, we found that OM-induced ER stress and osteogenic differentiation were ROS-dependent and that Hmox1 silencing triggered ROS production, ER stress and elevated osteogenic activity, which were inhibited by NAC. Overexpression of NQO1 mediated by adenovirus vectors significantly suppressed OM-induced ER stress and osteogenic markers. Collectively, these results showed the anti-osteogenic effects of OI on AVICs by regulating the generation of ROS and ER stress by activating the Nrf2 signaling pathway. Furthermore, OI alleviated aortic stenosis in a mouse model with direct wire injury. Due to its antioxidant properties, OI could be a potential drug for the prevention and/or treatment of CAVD.

SOD2 overexpression in bone marrow‑derived mesenchymal stem cells ameliorates hepatic ischemia/reperfusion injury

Hepatic ischemia/reperfusion injury (HIRI) is a complex pathophysiological process that may develop after liver transplantation and resection surgery, as well as in uncontrolled clinical conditions. Bone marrow‑derived mesenchymal stem cells (BM‑MSCs) are potential targets for liver diseases. Thus, the present study aimed to investigate the effects of superoxide dismutase 2 (SOD2) overexpression in BM‑MSCs on HIRI by constructing a HIRI rat model. The adenoviral vector containing SOD2 and the corresponding control vector were designed and constructed, and SOD2‑overexpressing BM‑MSCs were injected into the tail vein of the rats. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, as well as pathological changes and the remnant liver regeneration rate were determined. The activities of SOD and glutathione peroxidase (GSH‑Px), and malondialdehyde (MDA) content were measured. Reactive oxygen species (ROS) were determined with 2',7'‑-dichlorofluorescein diacetate and measured via fluorescence microscopy. Cell apoptosis was assessed using TUNEL staining. Moreover, the expression levels of Bax, Bcl‑2 and caspase‑3 were detected via western blotting. SOD2‑overexpressing BM‑MSCs significantly reduced the elevation of serum AST and ALT levels. Furthermore, SOD2‑overexpressing BM‑MSCs enhanced SOD and GSH‑Px activities, and suppressed the production of MDA and ROS. Histopathological findings revealed that SOD2‑overexpressing BM‑MSCs decreased the number of TUNEL‑positive cells in the liver. It was also found that SOD2‑overexpressing BM‑MSCs promoted Bcl‑2 expression, but inhibited Bax and caspase‑3 expression in HIRI. Collectively, these findings suggest that SOD2‑overexpressing BM‑MSCs may provide therapeutic support in HIRI by inhibiting oxidative stress and hepatocyte apoptosis.