https://rnajc.ucsf.edu/sites/rnajc.ucsf.edu/files/Warren%202010%20Cell%20Stem%20Cell.pdf

Highly efficient reprogramming to pluripotency and directed differentiation of human cells with synthetic modified mRNA

In vitro transcribed (IVT) mRNA has recently come into focus as a potential new drug class to deliver genetic information. Such synthetic mRNA can be engineered to transiently express proteins by structurally resembling natural mRNA. Advances in addressing the inherent challenges of this drug class, particularly related to controlling the translational efficacy and immunogenicity of the IVTmRNA, provide the basis for a broad range of potential applications. mRNA-based cancer immunotherapies and infectious disease vaccines have entered clinical development. Meanwhile, emerging novel approaches include in vivo delivery of IVT mRNA to replace or supplement proteins, IVT mRNA-based generation of pluripotent stem cells and genome engineering using IVT mRNA-encoded designer nucleases. This Review provides a comprehensive overview of the current state of mRNA-based drug technologies and their applications, and discusses the key challenges and opportunities in developing these into a new class of drugs.

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mRNA-based therapeutics — developing a new class of drugs

Memories can be unreliable. We created a false memory in mice by optogenetically manipulating memory engram-bearing cells in the hippocampus. Dentate gyrus (DG) or CA1 neurons activated by exposure to a particular context were labeled with channelrhodopsin-2. These neurons were later optically reactivated during fear conditioning in a different context. The DG experimental group showed increased freezing in the original context, in which a foot shock was never delivered. The recall of this false memory was context-specific, activated similar downstream regions engaged during natural fear memory recall, and was also capable of driving an active fear response. Our data demonstrate that it is possible to generate an internally represented and behaviorally expressed fear memory via artificial means.

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Creating a False Memory in the Hippocampus

Improved outcomes for patients with cancer hinge on the development of new targeted therapies with acceptable short-term and long-term toxicity. Progress in basic, preclinical, and clinical arenas spanning cellular immunology, synthetic biology, and cell-processing technologies has paved the way for clinical applications of chimeric antigen receptor– based therapies. This new form of targeted immunotherapy merges the exquisite targeting specificity of monoclonal antibodies with the potent cytotoxicity and long-term persistence provided by cytotoxic T cells. Although this field is still in its infancy, clinical trials have already shown clinically significant antitumor activity in neuroblastoma, chronic lymphocytic leukemia, and B cell lymphoma, and trials targeting a variety of other adult and pediatric malignancies are under way. Ongoing work is focused on identifying optimal tumor targets and on elucidating and manipulating both cell- and host-associated factors to support expansion and persistence of the genetically engineered cells in vivo. The potential to target essentially any tumor-associated cell-surface antigen for which a monoclonal antibody can be made opens up an entirely new arena for targeted therapy of cancer.

Chimeric Antigen Receptor Therapy for Cancer

mRNA as gene therapeutic: how to control protein expression.

mRNA transfection is a useful approach for temporal cell reprogramming with minimal risk of transgene-mediated mutagenesis. We applied this to redirect lymphocyte cytotoxicity toward malignant cells. Using the chimeric immune receptor (CIR) constructs anti-CD19 CIR and 8H9 CIR, we achieved uniform expression of CIRs on virtually the entire population of lymphocytes. We reprogrammed CD3+ CD8+, CD3+ CD4+, and natural killer (NK ) cells toward autologous and allogeneic targets such as B cells, Daudi lymphoma, primary melanoma, breast ductal carcinoma, breast adenocarcinoma, and rhabdomyosarcoma. The reprogramming procedure is fast. Although most of the experiments were performed on lymphocytes obtained after 7-day activation, only 1-day activation of T cells with anti-CD3, anti-CD28 antibodies, and interleukin-2 is sufficient to develop both lymphocyte cytotoxicity and competence for mRNA transfer. The entire procedure, which includes lymphocyte activation and reprogramming, can be completed in 2 da...

/pdf/chimeric-receptor-mrna-transfection-as-a-tool-to-generate-ep25d8ijdf.pdf

Chimeric receptor mRNA transfection as a tool to generate antineoplastic lymphocytes

A method of mRNA production for use in transfection is provided, that involves in vitro transcription of PCR generated templates with specially designed primers, followed by polyA addition, to produce a construct containing 3' and 5' untranslated sequence ('UTR'), a 5' cap and/or Internal Ribosome Entry Site (IRES), the gene to be expressed, and a polyA tail, typically 50-2000 bases in length. This RNA can efficiently transfect different kinds of cells. This approach results in increased efficiency (fidelity and productivity) of mRNA synthesis and is less time consuming because it does not require cloning, and also consequently eliminates the unwanted errors and effects related to RNA made on DNA templates obtained with cloning techniques. The results* of transfection of RNAs demonstrate that RNA transfection can be very effective in cells that are exceedingly difficult to transfect efficiently with DNA constructs. Further, the levels of gene expression following mRNA transfection are consistent from cell to cell in an experiment and these levels can be controlled over a wide range simply by changing the amount of mRNA that is transfected, and without obvious cytotoxic effects due to the levels of RNA per se. Due to high efficiency the cells can be simultaneously transfected with multiple genetic constructs. The method can be used to deliver genes into cells not- or only poorly transfectable for DNA, in vitro and in vivo.

Transient Transfection with RNA

RNA prepared by in vitro transcription using a polymerase chain reaction (PCR)-generated template can be introduced into a cell to modulate cell activity. This method is useful in de-differentiating somatic cells to pluripotent, multipotent, or unipotent cells; re-differentiating stem cells into differentiated cells; or reprogramming of somatic cells to modulate cell activities such as metabolism. Cells can also be transfected with inhibitory RNAs, such as small interfering RNA (siRNA) or micro RNA (miRNA), or combinations thereof to induce reprogramming of somatic cells. For example, target cells are isolated from a donor, contacted with one or more RNA's causing the cells to be de-differentiated, re-differentiated, or reprogrammed in vitro, and administered to a patient in need thereof. The resulting cells are useful for treating one or more symptoms of a variety of diseases and disorders, for organ regeneration, and for restoration of the immune system.

Method of de-differentiating and re-differentiating somatic cells using RNA

Advances in academic and clinical studies during the last several years have resulted in practical outcomes in adoptive immune therapy of cancer. Immune cells can be programmed with molecular modules that increase their therapeutic potency and specificity. It has become obvious that successful immunotherapy must take into account the full complexity of the immune system and, when possible, include the use of multifactor cell reprogramming that allows fast adjustment during the treatment. Today, practically all immune cells can be stably or transiently reprogrammed against cancer. Here, we review works related to T cell reprogramming, as the most developed field in immunotherapy. We discuss factors that determine the specific roles of αβ and γδ T cells in the immune system and the structure and function of T cell receptors in relation to other structures involved in T cell target recognition and immune response. We also discuss the aspects of T cell engineering, specifically the construction of synthetic T cell receptors (synTCRs) and chimeric antigen receptors (CARs) and the use of engineered T cells in integrative multifactor therapy of cancer.

T Cell Reprogramming Against Cancer.

mRNA has become an important alternative to DNA as a tool for cell reprogramming. To be expressed, exogenous DNA must be transmitted through the cell cytoplasm and placed into the nucleus. In contrast, exogenous mRNA simply has to be delivered into the cytoplasm. This can result in a highly uniform transfection of the whole population of cells, an advantage that has not been observed with DNA transfer. The use of mRNA, instead of DNA, in medical applications increases protocol safety by abolishing the risk of transgene insertion into host genomes. In this chapter, we review the aspects of mRNA structure and function that are important for its "transgenic" behavior, such as the composition of mRNA molecules and complexes with RNA binding proteins, localization of mRNA in cytoplasmic compartments, translation, and the duration of mRNA expression. In immunotherapy, mRNA is employed in reprogramming of antigen presenting cells (vaccination) and cytolytic lymphocytes. Other applications include generation of induced pluripotent stem (iPS) cells, and genome engineering with modularly assembled nucleases. The most investigated applications of mRNA technology are also reviewed here.

Peter M. Rabinovich

Papers

Chimeric receptor mRNA transfection as a tool to generate antineoplastic lymphocytes

Transient Transfection with RNA

Method of de-differentiating and re-differentiating somatic cells using RNA

T Cell Reprogramming Against Cancer.

Cell engineering with synthetic messenger RNA.