Gene therapy: therapeutic applications and relevance to pathology

Co-delivery of genes can be confounded by bicistronic vector design

Maximizing the efficiency of nanocarrier-mediated co-delivery of genes for co-expression in the same cell is critical for many applications. Strategies to maximize co-delivery of nucleic acids (NA) focused largely on carrier systems, with little attention towards payload composition itself. Here, we investigated the effects of different payload designs: co-delivery of two individual "monocistronic" NAs versus a single bicistronic NA comprising two genes separated by a 2A self-cleavage site. Unexpectedly, co-delivery via the monocistronic design resulted in a higher percentage of co-expressing cells, while predictive co-expression via the bicistronic design remained elusive. Our results will aid the application-dependent selection of the optimal methodology for co-delivery of genes.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1557/s43579-021-00128-7.

Imaging modalities for the in vivo surveillance of mesenchymal stromal cells

Bone marrow stromal cells exist as mesenchymal stromal cells (MSCs) and have the capacity to differentiate into multiple tissue types when subjected to appropriate culture conditions. This property of MSCs creates therapeutic opportunities in regenerative medicine for the treatment of damage to neural, cardiac and musculoskeletal tissues or acute kidney injury. The prerequisite for successful cell therapy is delivery of cells to the target tissue. Assessment of therapeutic outcomes utilize traditional methods to examine cell function of MSC populations involving routine biochemical or histological analysis for cell proliferation, protein synthesis and gene expression. However, these methods do not provide sufficient spatial and temporal information. In vivo surveillance of MSC migration to the site of interest can be performed through a variety of imaging modalities such as the use of radiolabelling, fluc protein expression bioluminescence imaging and paramagnetic nanoparticle magnetic resonance imaging. This review will outline the current methods of in vivo surveillance of exogenously administered MSCs in regenerative medicine while addressing potential technological developments. Furthermore, nanoparticles and microparticles for cellular labelling have shown that migration of MSCs can be spatially and temporally monitored. In vivo surveillance therefore permits time-stratified assessment in animal models without disruption of the target organ. In vivo tracking of MSCs is non-invasive, repeatable and non-toxic. Despite the excitement that nanoparticles for tracking MSCs offer, delivery methods are difficult because of the challenges with imaging three-dimensional systems. The current advances and growth in MSC research, is likely to provide a wealth of evidence overcoming these issues.

Gene therapy approaches to regenerating bone

Bone formation and regeneration therapies continue to require optimization and improvement because many skeletal disorders remain undertreated. Clinical solutions to nonunion fractures and osteoporotic vertebral compression fractures, for example, remain suboptimal and better therapeutic approaches must be created. The widespread use of recombinant human bone morphogenetic proteins (rhBMPs) for spine fusion was recently questioned by a series of reports in a special issue of The Spine Journal, which elucidated the side effects and complications of direct rhBMP treatments. Gene therapy - both direct (in vivo) and cell-mediated (ex vivo) - has long been studied extensively to provide much needed improvements in bone regeneration. In this article, we review recent advances in gene therapy research whose aims are in vivo or ex vivo bone regeneration or formation. We examine appropriate vectors, safety issues, and rates of bone formation. The use of animal models and their relevance for translation of research results to the clinical setting are also discussed in order to provide the reader with a critical view. Finally, we elucidate the main challenges and hurdles faced by gene therapy aimed at bone regeneration as well as expected future trends in this field.

Tianma modulates proteins with various neuro-regenerative modalities in differentiated human neuronal SH-SY5Y cells

Tianma (Rhizoma gastrodiae) is the dried rhizome of the plant Gastrodia elata Blume (Orchidaceae family). As a medicinal herb in traditional Chinese medicine (TCM) its functions are to control convulsions, pain, headache, dizziness, vertigo, seizure, epilepsy and others. In addition, tianma is frequently used for the treatment of neurodegenerative disorders though the mechanism of action is widely unknown. Accordingly, this study was designed to examine the effects of tianma on the proteome metabolism in differentiated human neuronal SH-SY5Y cells to explore its specific effects on neuronal signaling pathways. Using an iTRAQ (isobaric tags for relative and absolute quantitation)-based proteomics research approach, we identified 2390 modulated proteins, out of which 406 were found to be altered by tianma in differentiated human neuronal SH-SY5Y cells. Based on the observed data, we hypothesize that tianma promotes neuro-regenerative signaling cascades by controlling chaperone/proteasomal degradation pathways (e.g. CALR, FKBP3/4, HSP70/90) and mobilizing neuro-protective genes (such as AIP5) as well as modulating other proteins (RTN1/4, NCAM, PACSIN2, and PDLIM1/5) with various regenerative modalities and capacities related to neuro-synaptic plasticity.

Involvement of actin cytoskeleton in macrophage apoptosis induced by cationic liposomes

We clarified whether actin cytoskeleton is involved in the macrophage apoptosis induced by cationic liposomes composed of stearylamine (SA-liposomes). Externalization of phosphatidylserine induced by SA-liposomes was suppressed by cytochalasin D, a specific inhibitor of polymerization of F-actin. Furthermore, activation of PKCδ and reactive oxygen species (ROS) generation, which could be involved in the macrophage apoptosis, were inhibited by cytochalasin D. Microscopical observation revealed the co-localization of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI)-labeled SA-liposomes and fluorescein-labeled phalloidin, which specifically binds to F-actin, and this co-localization was also inhibited by cytochalasin D. Co-localization of SA-liposomes and F-actin was also inhibited by the pre-treatment of cells with chondroitinase ABC. These findings could be the first observation concerning the contribution of the proteoglycan-actin cytoskeleton-ROS generation pathway to apoptosis induced by SA-liposomes in macrophages.