Amid new research implicating extracellular RNAs in a variety of biological processes, the National Institutes of Health has launched a new program to support research around the release, transport, uptake, and regulatory role of these molecules.
As part of the initiative, NIH has set aside nearly $22 million to bankroll five funding opportunities for investigative projects related to different aspects of exRNA science including its therapeutic and diagnostic potential, as well as the creation of a resource to handle and disseminate data resulting from such work.
Though originally believed to exist solely inside of cells to facilitate protein translation, RNAs are now known to be involved in a range of cellular functions, including mechanisms of cell-to-cell communication, according to NIH. “RNA can be exported from cells in extracellular vesicles or bound to lipids or proteins, to circulate through the body, and affect cells at a great distance.”
Still, the full impact of exRNAs remains unclear. To address this shortcoming, NIH has established the Extracellular RNA Communication program, which is tasked with aiding in the discovery of the “fundamental biological principles about the mechanisms of exRNA generation, secretion, and transport,” according to the agency.
Additionally, the new program will help researchers “identify and develop a catalog of exRNA found in normal human body fluids; and ... investigate the potential for using exRNAs in the clinic as therapeutic molecules or biomarkers of disease.”
Advancing the exRNA field will require “both fundamental scientific discovery and innovative tools and technologies,” NIH said. Of particular importance will be “defining the fundamental principles of exRNA biogenesis, distribution, uptake, and function; and developing the molecular tools, technologies, and imaging modalities to enable these studies.”
To that end, the Extracellular RNA Communication program will provide $7.2 million to fund between four and six research projects that address these issues.
In terms of biogenesis, NIH noted that three main regulatory RNA species — protein-coding RNA, long non-coding RNA, and microRNA — have been identified in extracellular space and mediate intracellular communication. Vesicles and RNA-binding carriers have been reported to transport these RNAs extracellularly, but the pathways by which they are directed to specific secretory pathways and taken up by target cells still need to be elucidated.
Among the types of projects eligible for funding here would be ones that determine the biosynthetic pathways by which exRNAs are sorted to vesicles, and ones that identify inhibitors of proteins that control exRNA sorting and release.
When it comes to biodistribution, NIH said that although exRNAs have been found at high concentrations in serum and other body fluids, which suggests that they are protected from degradation, the mechanisms that regulate their stability and distribution outside the cell have yet to be defined.
Areas of emphasis here include the co-factors that affect exRNA biodistribution and systems and tools that track distribution in vivo.
For exRNA uptake, there are reports that implicate specific cell surface-targeting motifs on extracellular vesicles that mediate contact with target cells and fusion events; however, other mechanisms are likely involved, NIH said. For this aspect of the research program, areas of interest include the identification of specific factors and their receptors on target cells that mediate binding and uptake, and the determination of how exRNAs access specific subcellular compartments.
With regards to exRNA function, NIH said that it is especially interested in research proposals related to the functional outcomes on target cell phenotypes following exRNA interaction; potential molecular targets of exRNAs; and the co-factors that contribute to exRNA effector function within a target cell.
Seeing potential clinical applications for exRNAs, NIH said that there is a need for a reference catalog of the molecules present in normal, healthy biofluids. “A systematic analysis of circulating and other body fluids will provide a reference base for novel strategies for diagnosis, intervention, and therapy for many diseases,” it stated.
To assist with the development of such a resource, the Extracellular RNA Communication program has earmarked $4 million to fund between three and five projects related to the development of human reference profiles for non-coding exRNA species from blood and other body fluids in order to generate a “comprehensive catalog” that includes exRNAs secreted in extracellular vesicles or bound to carrier proteins.
Also eligible for funding are research efforts focused on the development of reference profiling methods that facilitate identification of both endogenously derived and exogenously obtained exRNA species; the capture of trans-kingdom exRNAs that could improve the understanding of associations between environmental exposures and health or disease; and the creation of tools, methodologies, and techniques required to generate reference exRNA profiles and distinguish exogenously derived species from trans-kingdom ones.
An additional $4 million has been set aside to fund between six and eight projects related specifically to the identification and validation of exRNA-based biomarkers “readily available from human body fluids,” as well as ones that help assess and qualify such biomarkers for use in a clinical setting.
Projects covered under this funding opportunity may involve exploratory work that identifies biomarkers derived from biofluid exRNAs with “characteristics unique to human disease conditions that might lead to potential clinical utility,” NIH said. “An ideal biomarker can be measured in a minimally invasive way, can be measured repeatedly over time, is indicative of disease prognosis, and correlates well with progression and response to therapy.”
Also up for consideration are projects that support the validation and quantification of already identified biomarkers. These include studies in human subjects to determine whether a biomarker correlates well with pathogenesis, disease processes, progression or regression of disease, or response to therapy; and studies to design or improve an exRNA biomarker assay system to be “robust, quantitative, reliable, and translatable to many laboratories,” NIH said.
Meanwhile, a further $4 million will be used to fund between six and eight projects that look to the therapeutic potential of exRNAs and the development of methods and tools that will enable their targeting to specific cells.
“Support will be provided for proof-of-principle studies to develop and advance the therapeutic utility of exRNAs, RNA-containing extracellular vesicles or exosomes, and/or exRNA-bound to other carrier molecules, such as lipoproteins and RNA-binding complexes,” NIH noted. Eligible projects should “establish the biological rationale for the proposed therapeutic use, identify the dose or exposure of the therapeutic agent in the proposed patient group, develop appropriate methods for in vivo tracking, and inform patient selection.”
Additionally, projects involving the preclinical optimization and testing of the exRNA therapeutic leads will also be considered. These must include sufficient demonstration of the utility of one or more identified exRNA therapeutic leads, as well as in vivo data on efficacy, NIH said.
Finally, the Extracellular RNA Communication program plans to grant a single $2.5 million award to support a data management resources/repository, or DMRR, that will handle the development of a community resource that gives access to exRNA data, standardized exRNA protocols, and other tools and technologies generated by the program's participants.
The so-called exRNA Atlas will essentially integrate the efforts of all of the other components of the Extracellular RNA Communication program and serve as a “community-wide resource for exRNA standards, protocols, and data,” NIH said.
Specific duties for the DMRR will include development a website for the atlas; organization of workshops and a community outreach strategy to “further develop a cadre of ExRNA researchers, build community consensus as needed, and to disseminate ERCP protocols and resources to the broad scientific community;” and coordination of the Extracellular RNA Communication program's consortium of researchers through steering committee and grantee meetings.
“The anticipated functions of the DMRR require an administrative core, as well as three distinct stand-alone components in the areas of scientific outreach, data coordination, and data integration and analysis,” NIH said.
Applications for all of the funding opportunities are due by Nov. 13. A review of their scientific merit will be conducted between February and March of next year, with an advisory council review occurring in May.
The earliest start date for all projects will be July 2013.