New Allele Biotech Publication on Stem Cells

Feeder-Free Reprogramming of Human Fibroblasts with Messenger RNA
Current Protocols in Stem Cell Biology • November 13, 2013
DOI: 10.1002/9780470151808.sc04a06s27

Authors: Luigi Warren, Jiwu Wang

This unit describes a feeder-free protocol for deriving induced pluripotent stem cells (iPSCs) from human fibroblasts by transfection of synthetic mRNA. The reprogramming of somatic cells requires transient expression of a set of transcription factors that collectively activate an endogenous gene regulatory network specifying the pluripotent phenotype. The necessary ectopic factor expression was first effected using retroviruses; however, as viral integration into the genome is problematic for cell therapy applications, the use of footprint-free vectors such as mRNA is increasingly preferred. Strong points of the mRNA approach include high efficiency, rapid kinetics, and obviation of a clean-up phase to purge the vector. Still, the method is relatively laborious and has, up to now, involved the use of feeder cells, which brings drawbacks including poor applicability to clinically oriented iPSC derivation. Using the methods described here, mRNA reprogramming can be performed without feeders at much-reduced labor and material costs relative to established protocols.

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Wednesday, November 13th, 2013 iPSCs and other stem cells No Comments

Picture Blog: mRNA Reprogramming for Human iPSCs without B18R!

Human induced pluripotent stem cells provide a great route towards personalized medicine and high accuracy drug screening. Allele Biotech has developed the most efficient method of making human iPSCs by using enhanced mRNAs, which have been adopted by leading pharmaceutical companies for clinical trials. The effects from medium-supplementing mRNAs are robust yet transient, and highly specific compared to both miRNAs (off-targets) and small molecules (unknown targets). To repress cellular immune response to introduced RNA molecules, viral protein B18R was previously used during mRNA reprogramming.

B18R is relatively expensive and inconvenient to use because it requires pre-aliquoting and -80C storage. The protocol has recently been dramatically improved at Allele through an NIDA-funded project. In our latest reprogramming run, all we needed to do was to include mRNA complex in the supplement during medium change for just a week without the need of adding any other type of molecules (such as B18R, miRNA, or chemicals) to help the mRNA mix, unlike all other known mRNA-reprogramming protocols. This advancement can make reprogramming human fibroblasts to footprint-free and xeno-free iPSCs a routine experiment for any lab to perform.

Human R-iPSCs were created without the need of B18R, dramatically reduced the cost and inconvenience. Shown is a newly formed iPSC colony.

mRNA reprogramming used to require B18R to repress cellular immune response from repeated exposure to RNA molecules.  Allele scientists lead by Dr. Jiwu Wang further developed their technology to bypass the use of B18R or any immune repressor.

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Thursday, August 15th, 2013 iPSCs and other stem cells Comments Off on Picture Blog: mRNA Reprogramming for Human iPSCs without B18R!

Allele Biotech Receives $200,000 Grant to Update Its mRNA Reprogramming Commercial Products and Services

On June 10, 2013 Allele received an SBIR award from the National Institute of Drug Abuse (NIDA/NIH) entitled “Revolutionary Technology for Efficient Derivation of Human iPSCs with Messenger RNA”. The goal of the proposed project is to provide to the biomedical research market an advanced reagent kit and services for highly efficient reprogramming of high quality human induced pluripotent stem cells (iPSCs). At the core of this kit is the Allele team’s recent development transcribed messenger RNA (mRNA). Compared to other reprogramming methods, such as lentivirus, Sendai virus, protein, small molecules or any combinations of these reagents, our new generation of the mRNA method often requires less than half the time while sometimes achieving “bulk conversion” efficiency.

While the Allele reprogramming technology was designed for clinical use as the process is feeder-free, xeno-free, chromosome integration-free, as well as without the need for cell splitting, PI, Dr. Jiwu Wang states, “Our purpose of executing the NIH-funded research it to make our method so easy that any researcher can integrate iPSC into his or her projects.” In addition to the extremely high efficiency, mRNA-generated iPSCs should also be more stable because there are no genetic alterations, more uniform among all clones as there is no clonal event, and ultimately suitable for future autologous cell therapy now that creating iPSCs from patient tissue cells should no longer be the rate-limiting steps.

Allele’s business model is to provide cGMP-grade iPSCs to pharmaceutical companies and perform large scale reprogramming by partnering first with university-affiliated hospitals. Great progress has been made in both directions, which has prompted the initiation of a cGMP unit within Allele’s newly acquired building in San Diego.

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mRNA Transfection for Better Transgene Expression

Different approaches have been developed to over-express or ectopically express a protein in cells: peptide or full length recombinant protein transfer, viral gene transfer, non-viral DNA transfer and non-viral mRNA transfer.

1) Peptide transfection can be efficient, yet it is limited to only a small part of the protein, limiting the functional potential. Protein transfection is not consistent enough so far, because of the complicated properties of different proteins. Allele Biotech has tested dozens of proteins with several proprietary reagents, leader peptides, etc. but we have decided not to carry a protein transfection product line due to its instability. Furthermore, protein production is an expensive and laborious process.

2) Viral gene transfer is very effective, such as the HIV-based lentivirus or MMLV-based retrovirus, adenovirus, adeno-like virus or baculovirus, etc. However, the potent side-effect will still need to be considered for certain applications, especially involving clinical studies. Nevertheless, as research tools, viral gene transfer is still a highly preferred method. Allele Biotech has been providing the most effective platform for both MMLV-based and HIV-1-based retrovirus packaging. Check out our product website for details.

3) Non-viral DNA transfer is the most widely used transgene method in the biological research community, due to the simplicity of the procedure. There are many commercial kits on the market. However, the low efficiency for transfecting most primary cells significantly limits their use. In recent years, several leading biotech companies have developed various electroporation systems to improve the transfection efficiency and cell viability; although these improvements help with getting DNA inside the cytoplasm, they hardly help transport it into nucleus where DNA is transcribed.

4) Non-viral mRNA transfer has been around for a long time, but it is not widely used. It made a big splash recently through its use for iPSCs reprogramming. IPSCs factor mRNAs greatly improved the iPSCs induction efficiency and completely avoided the viral integration. Other well-known examples of mRNA transfection include loading special cancer antigens or HIV antigens to dendritic cells (DCs) in vitro for personal immunotherapy. PSA antigen expressing DCs transfected by mRNA has moved on to Phrase I Clinical Trials for this purpose.

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