LoxP 4-in-1 iPS Factor on Lentiviral Vectors for Efficient Reprogramming

Putting 4 iPS factors on one lentiviral vector, separated by 2A peptides, has appeared to be more efficient in generating iPS cells than having all 4 factors on individual viruses, at least in a number of cases. Stem cell-like colonies start to appear in about 2 weeks using Allele Biotech’s 4-in-1 lentivirus. In addition to the concerted effects from Oct3/4, Sox2, c-Myc, Klf4, it is also believed that the coordinated silencing of these factors after reprogramming help forming iPS colonies.

The 4-in-1 lentivirus from Allele Biotech contains loxP sites that can be used to remove the 4 cDNAs if so desired. For convenience, a new product kit is offered starting this week to include lenti-nCre in a kit with the 4-in-1 iPS viral products.

New Product of the Week 04-11-10 to 04-18-10: 4-In-One-Vector: Human OSKM Lentiviral Paticles (Oct3/4, Sox2, Klf4 and c-Myc) and Cre Lentiviral Particle kits, Cat # ABP-SC-LVI4IN1C1 or ABP-SC-LVI4IN1C5

Promotion of the Week 04-11-10 to 04-18-10: Single vial 4-in-1 is offered only this week. This product has been well established and validated, one of the reasons smaller packages are not normally offered. As a matter of fact, every batch of the 4-in-1 iPS lentivirus has been sold out.

Update note: Lentivirus inserts into the host chromosome, and is gradually being replaced by footprint-free reprogramming reagents, the best being Allele Biotech’s enhanced mRNA reprogramming factors that feature a patent-pending fusion gene.

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Launch of Allele-iPS Product Line

Induced pluripotent stem cells, or iPS (or iPSC as some call it), are differentiated cells from adult that “regained” capabilities to differentiate into all 3 germ layer specific cell types. The iPS induction process currently involves using viral vectors to introduce 3 or 4 cDNAs, which seemed surprisingly simple considering how complex it is for stem cells to go through each differentiation pathway.

The potentials of using iPS as models for research, cell assay systems, drug screening, toxicological testing, etc., seem to be tremendous at this point. However, for therapeutic use, the biggest hurdle standing in the way is the tendency of these iPS cells to form tumors once transplanted. It could be due to the oncogenic nature of the stemness inducing cDNAs themselves, or the retrovirus or lentivirus used for bring the cDNAs into the cells. A number of labs like that of Sheng Ding at Scripps, San Diego (Li et al., 2009), and Doug Melton at Harvard (Huangfu et al., 2008a; Huangfu et al., 2008b), are screening chemicals that would replace the use of some or maybe eventually all of the cDNAs. Such advances may help mitigate the oncogenic effects possibly associated with the inducing genes. Using non-integrating vectors as carriers would be preferred method for gene transfer if the retroviral or lentiviral vectors are the cause of tumors from iPS.

Today is the day that Allele launches its iPS product line, officially in this exciting field as one of the very first companies that produce products to make iPS research easier for everybody. New products in the pipeline include those for iPS induction and detection, stem cell culturing, differentiation tracking, and safer, novel delivery methods. It is just the beginning!

Huangfu, D., Maehr, R., Guo, W., Eijkelenboom, A., Snitow, M., Chen, A.E., and Melton, D.A. (2008a). Induction of pluripotent stem cells by defined factors is greatly improved by small-molecule compounds. Nature biotechnology 26, 795-797.
Huangfu, D., Osafune, K., Maehr, R., Guo, W., Eijkelenboom, A., Chen, S., Muhlestein, W., and Melton, D.A. (2008b). Induction of pluripotent stem cells from primary human fibroblasts with only Oct4 and Sox2. Nature biotechnology 26, 1269-1275.
Li, W., Wei, W., Zhu, S., Zhu, J., Shi, Y., Lin, T., Hao, E., Hayek, A., Deng, H., and Ding, S. (2009). Generation of rat and human induced pluripotent stem cells by combining genetic reprogramming and chemical inhibitors. Cell stem cell 4, 16-19.

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Wednesday, March 18th, 2009 iPSCs and other stem cells No Comments