Frequently Asked Questions
FlashRNA® technology
What is the nature of RNA packaged in FlashRNA® particles?
RNA incorporated within FlashRNA® particles is transcribed endogenously in producer cells during particle assembly, thereby constituting biological RNA rather than synthetic, in vitro–transcribed RNA. As a consequence, these RNAs possess the full repertoire of natural post-transcriptional modifications introduced by human cellular machinery, reflecting authentic modification patterns found in physiologically expressed RNA species.
What are the differences between FlashRNA® and LNPs?
LNPs are synthetic, whereas FlashRNA® is biologically derived. All FlashRNA® components are synthesized in human producer cells. So, FlashRNA® encapsulates biological RNAs of human origin and not synthetic, in vitro-transcribed RNA, like LNPs. Moreover, FlashRNA® is a complex, multi-layered structure allowing protection of the packaged RNAs, thanks to a protein capsid surrounded by a biological lipid membrane. Thus, as a bioengineered virus-like particle (VLP), FlashRNA® has a lower intrinsic immunogenicity and highly efficient entry into a broad range of cell types, compared to LNPs.
What types of RNA can FlashRNA® deliver?
FlashRNA® can deliver various RNA types, including mRNAs, guide RNAs, coding and non-coding RNAs. For example, for gene editing, Cas9 mRNA and single guide RNAs can be packaged within the same particle.
What is the maximum RNA payload capacity of FlashRNA®?
FlashRNA® technology supports a high payload capacity, enabling the delivery of both small and large RNAs. Specifically, it can deliver multiple RNA molecules, including large RNAs up to 10 kilobases (kb) in length. This makes FlashRNA® suitable for complex applications such as cell reprogramming, gene editing, and immunotherapy, where the simultaneous delivery of several and/or large RNA molecules is required.
Is there generation of DNA after RNA transfer by FlashRNA®?
No, the delivered RNAs are directly used by the target cell. There is no possibility of reverse transcription nor integration, as the LTRs and integrase have been deleted.
Is FlashRNA® already used in therapy?
Yes, FlashRNA® has been produced as a Drug Product, to be used for a First-in-Human phase 1/2 clinical trial in 2025 (LymphARN trial, to treat secondary lymphedema).
Applications
Is FlashRNA® capable of engineering difficult-to-transduce cells ?
We achieve excellent transduction rates for all cell types, including those difficult to transduce, such as primary cells and stem cells. For difficult-to-transduce cells or sensitive cells, we recommend using the Premium production grade to achieve the highest transduction efficiency.
Is it possible to target a specific cell type?
Engineering the FlashRNA® particles to modify their tropism is definitely possible, as has already been demonstrated with similar particles. It is one of our main R&D projects, and we are working on it with the goal of using FlashRNA® to target any given cell type after direct in vivo administration.
Is FlashRNA® redosable?
Yes, FlashRNA® has been tested in vivo, with up to three successive injections, without generating toxicity or a non-specific immune response.
Which administration routes are possible?
A variety of routes of administration have been assessed in vivo. These include intravenous (IV), intramuscular (IM), intradermal (I.D.), subcutaneous (SC), and stereotactic administration, as well as intra-articular (in the joint) administration.
Can FlashRNA® be used to deliver gene editing systems?
Yes, nuclease mRNA and single guide RNAs can be packaged within the same particle. FlashRNA® has already been used in many types of primary cells, from stem cells to immune cells, as well as human induced pluripotent stem cells (iPSCs), showing an efficient gene editing without compromising cell viability or the differentiation capacity of stem cells.
Technical questions
What is the duration of RNA expression with FlashRNA®?
The RNA expression with FlashRNA® is transient, meaning it lasts for a short period. The duration of expression is related to the half-life of the protein being expressed. Typically, for a short half-life reporter, protein expression is detectable from 4 hours post-transduction and reaches a peak after around 24 hours, before decreasing. For a long half-life reporter, expression can be detected up to 7 days after transduction.
How many RNA can be delivered with FlashRNA®?
We have been able to transfer 4 different genes so far, but this is not the limit.
Which dose of FlashRNA® do I need to use on my cells?
The optimal dose of FlashRNA® for your cells depends on several factors, including the specific application, cell type, and experimental context. Doses are expressed in pg of p24 protein per cell. Typically for ex-vivo transductions, doses between 0,1 pg and 5 pg p24 / cell are sufficient to obtain a very efficient expression.
How should the FlashRNA particles be stored?
FlashRNA® particles must be stored at -80°C immediately upon receipt.
What is the shelf life of the product when stored at -80°C after receipt?
Products can be kept for more than 10 years when stored at -80°C after receipt.
How should FlashRNA particles be thawed?
FlashRNA® particles must be taken out of the -80°C freezer at the last moment. On removal from the -80°C freezer, the particles must be placed on ice to begin the thawing protocol. Once thawed, the FlashRNA® must be rapidly used for transduction. It is also essential to avoid thermal shocks to ensure particle efficiency. Contact us for more details.
Are the cells modified by FlashRNA® considered as GMO?
The FlashRNA®-modified cells are not considered as GMO, as the GOI expression is transient. There is one exception: if FlashRNA® is used to deliver a genome editing system, like CRISPR/Cas9, that induces permanent genome modifications in the target cell.
What do I need to provide to get my project started?
Only the names of your GOIs or their sequences are needed. RNAlead’s experts will handle the molecular design so you get the best solution for your project.