Cell and gene therapy in Australia

The expansion of human cells to produce cell therapeutic products for the treatment of disease is, with few exceptions, an experimental therapy. Because cell therapies involve a biological product, often with some genetic or other modification, they require extensive pre-clinical research and development. Cell therapy production processes and premises require licensing by the Therapeutic Goods Administration. In this review, timed to coincide with the international meetings of the ISCT and ISSCR in Australia, we describe some promising cell therapies currently under development

Cell, tissue and gene products with marketing authorization in 2018 worldwide

Cell and gene therapies (CGTs) are progressively entering into clinical practice in different parts of the world. The International Society for Cell & Gene Therapy (ISCT), a global scientific society, has been committed since 1992 to supporting and developing knowledge on clinical applications of CGTs. Considering the number of products that have been progressively approved and, in some cases, withdrawn in recent years, the ISCT would like to present a brief annual report on CGTs with marketing authorization (MA) in different regions. This article reflects the dynamic momentum around authorized CGTs coinciding with the parallel increase of unproven approaches where cells are delivered without appropriate and rigorous scientific and regulatory assessment and authorization. This is intended to be a living document with a yearly update linked to a dedicated section of the ISCT website for faster adjustments. The aim is to ultimately inform, by periodic snapshots, the scientific community, healthcare stakeholders and patient associations on authorized CGT products as a way to increase communication around the approved therapeutic approaches charged with heightened expectations

Improved granulocyte colony-stimulating factor mobilization of hemopoietic progenitors using cytokine combinations in primates

Peripheral blood stem cells (PBSCs), usually mobilized with granulocyte colony-stimulating factor (G-CSF) alone or in combination with chemotherapy, are the preferred source of cells for hemopoietic stem cell transplantation. Up to 25% of otherwise eligible transplant recipients fail to harvest adequate PBSCs. Therefore it is important to investigate existing and novel reagents to improve PBSC mobilization. Because of marked interindividual variation in humans, we developed a robust nonhuman primate model that allows the direct comparison of the efficacy of two PBSC mobilization regimens within the same animal. Using this model, we compared pegylated G-CSF (pegG-CSF) with standard G-CSF and compared the combination of G-CSF and pegylated megakaryocyte growth and development factor (pegMGDF) with G-CSF plus stem cell factor (SCF) by measuring the levels of CD34+ cells, colony-forming cells (CFCs), and SCID repopulating cells (SRCs) before and after cytokine administration. Mobilization of CD34+ cells, CFCs and SRCs using pegG-CSF achieved similar levels to those resulting from 5 days of standard G-CSF. The combination of G-CSF+pegMGDF mobilized progenitors to levels similar to G-CSF+SCF but greater than standard G-CSF for CD34+ cells and CFC. This first direct comparison of PBSC mobilization in individual primates demonstrates that peg-G-CSF is equivalent to daily G-CSF and that the addition of pegMGDF to G-CSF improves mobilization. In light of the development of new thrombopoietin agonists, these data offer the potential for improved stem cell mobilization strategies. ©AlphaMed Press

EGF-activated PI3K/Akt signalling coordinates leucine uptake by regulating LAT3 expression in prostate cancer

Background: Growth factors, such as EGF, activate the PI3K/Akt/mTORC1 signalling pathway, which regulates a distinct program of protein synthesis leading to cell growth. This pathway relies on mTORC1 sensing sufficient levels of intracellular amino acids, such as leucine, which are required for mTORC1 activation. However, it is currently unknown whether there is a direct link between these external growth signals and intracellular amino acid levels. In primary prostate cancer cells, intracellular leucine levels are regulated by L-type amino acid transporter 3 (LAT3/SLC43A1), and we therefore investigated whether LAT3 is regulated by growth factor signalling. Methods: To investigate how PI3K/Akt signalling regulates leucine transport, prostate cancer cells were treated with different PI3K/Akt inhibitors, or stable knock down of LAT3 by shRNA, followed by analysis of leucine uptake, western blotting, immunofluorescent staining and proximity ligation assay. Results: Inhibition of PI3K/Akt signalling significantly reduced leucine transport in LNCaP and PC-3 human prostate cancer cell lines, while growth factor addition significantly increased leucine uptake. These effects appeared to be mediated by LAT3 transport, as LAT3 knockdown blocked leucine uptake, and was not rescued by growth factor activation or further inhibited by signalling pathway inhibition. We further demonstrated that EGF significantly increased LAT3 protein levels when Akt was phosphorylated, and that Akt and LAT3 co-localised on the plasma membrane in EGF-activated LNCaP cells. These effects were likely due to stabilisation of LAT3 protein levels on the plasma membrane, with EGF treatment preventing ubiquitin-mediated LAT3 degradation. Conclusion: Growth factor-activated PI3K/Akt signalling pathway regulates leucine transport through LAT3 in prostate cancer cell lines. These data support a direct link between growth factor and amino acid uptake, providing a mechanism by which the cells rapidly coordinate amino acid uptake for cell growth

Specific adeno-associated virus serotypes facilitate efficient gene transfer into human and non-human primate mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) show great promise for ex vivo gene and cell-mediated therapies. The immunophenotype and in vitro differentiation capacity of primary baboon MSCs was demonstrated to be near-identical to that observed in human MSCs. To optimize gene transfer efficiency, we compared the efficiency of serotypes 1, 2, 3, 4, 5, 6, and 8 of adeno-associated virus (AAV) vectors for their ability to mediate transduction of human and baboon MSCs. AAV serotype 2 vectors were the most efficient in transducing MSCs from humans and baboons. As a reference, human Ad293 cells were transduced with these seven AAV serotypes, and were found to have the highest transduction levels followed by baboon MSCs, and then human MSCs. The order of increasing transduction efficiency for the serotypes tested was similar for human and baboon MSCs, but was different for human Ad293 cells. The transduction efficiency of MSCs isolated from different individuals was comparable within the same species. We also demonstrated that baboon MSCs transduced with AAV serotype 2 vectors retain their potential to differentiate into adipocytes in vitro, and can incorporate into injured muscle tissue of NODSCID mice in vivo. We detected β-galactosidase reporter gene expression in host muscle tissue for up to 9 weeks in this study, indicating engraftment of transduced baboon MSCs and sustained transgene expression in vivo. Copyright © 2006 John Wiley & Sons, Ltd

Identifying microRNA determinants of human myelopoiesis

Myelopoiesis involves differentiation of hematopoietic stem cells to cellular populations that are restricted in their self-renewal capacity, beginning with the common myeloid progenitor (CMP) and leading to mature cells including monocytes and granulocytes. This complex process is regulated by various extracellular and intracellular signals including microRNAs (miRNAs). We characterised the miRNA profile of human CD34+CD38+ myeloid progenitor cells, and mature monocytes and granulocytes isolated from cord blood using TaqMan Low Density Arrays. We identified 19 miRNAs that increased in both cell types relative to the CMP and 27 that decreased. miR-125b and miR-10a were decreased by 10-fold and 100-fold respectively in the mature cells. Using in vitro granulopoietic differentiation of human CD34+ cells we show that decreases in both miR-125b and miR-10a correlate with a loss of CD34 expression and gain of CD11b and CD15 expression. Candidate target mRNAs were identified by co-incident predictions between the miRanda algorithm and genes with increased expression during differentiation. Using luciferase assays we confirmed MCL1 and FUT4 as targets of miR-125b and the transcription factor KLF4 as a target of miR-10a. Together, our data identify miRNAs with differential expression during myeloid development and reveal some relevant miRNA-target pairs that may contribute to physiological differentiation

Orchestrated intron retention regulates normal granulocyte differentiation

Intron retention (IR) is widely recognized as a consequence of mis-splicing that leads to failed excision of intronic sequences from pre-messenger RNAs. Our bioinformatic analyses of transcriptomic and proteomic data of normal white blood cell differentiation reveal IR as a physiological mechanism of gene expression control. IR regulates the expression of 86 functionally related genes, including those that determine the nuclear shape that is unique to granulocytes. Retention of introns in specific genes is associated with downregulation of splicing factors and higher GC content. IR, conserved between human and mouse, led to reduced mRNA and protein levels by triggering the nonsense-mediated decay (NMD) pathway. In contrast to the prevalent view that NMD is limited to mRNAs encoding aberrant proteins, our data establish that IR coupled with NMD is a conserved mechanism in normal granulopoiesis. Physiological IR may provide an energetically favorable level of dynamic gene expression control prior to sustained gene translation. © 2013 Elsevier Inc