Archive for February, 2014

What Does It Take to Bring New Nano Antibodies (nAbs) to the Hands of Researchers?

Judging from the hundreds of papers published using camelid VHH antibodies as reagents, there are probably thousands of researchers who have experience with this type of antibodies by now. We like to call the ~15kD camelid VHH antibody nano antibody or nAbTM. Once someone experiences how well a nAb works for co-IP using a fluorescent protein as tag, they often wonder what it takes to bring nAbs to broader use.

The success of a nAb project starts with the antigen presentation. It is critical to build the capability to produce large quantities of recombinant antigen for immunization. At Allele, our scientists also established some unique presentation formats for traditionally difficult targets (e.g. large membrane proteins).

After llama immunization, the next step is screening. With the goal of creating large scale nano antibodies against diverse targets, we have developed multiple high throughput screening methods to cover very large, diverse libraries generated from immunized animals. The technologies will continue to evolve as the scale of nAb generation continues to expand. We have the ability to functionally screen for site-blocking antibodies and antibodies that only recognized natively folded targets, or targets in their naturally occurring presentations.

A nAb isolation project does not end with the obtaining of a cDNA clone. Or, if it does, the nAb is probably not as great as what Allele Biotech has been offering. In our hands, all nAbs go through an engineering step beginning with the generation of a 3D structural model of the isolated clone. We use structure-guided design to alter the protein, allowing us to improve its properties. This includes increasing affinity, solubility, or altering the protein to improve performance for specific applications. We also like to use known structures of traditional monoclonal antibodies to assist camelid VHH antibody engineering against specific targets.

With a finalized clone in hand, the next step is to establish protocols for commercial production. The Allele team spends a tremendous amount of effort aimed solely at high-yield, low-cost recombinant VHH antibody production in a variety of formats, so that the costs for other scientists to take advantage of these great reagents can be kept as low as possible.

Last but not the least, nAb labeling, including conjugating stable soluble VHH antibody to solid supports for immunoprecipitation or to fluorophores for detection, requires additional expertise and tight operation control. However, our vision is to have a modular system for antibody labeling that will enable the end user to select from a variety of fluorophores and other detection tags, which can be instantaneously and irreversibly coupled via simple mixing.

Note added: we work with commercial (diagnostic and clinical) partners from developing nAbs all the way to the market. We have expert scientists available to customers and licensees for consultation and troubleshooting antibody- and imaging-related questions and problems.

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Picture Blog: A Short Path from Human mRNA-iPSCs to Neurons in Record Speed

Traditional differentiation protocols use embryoid body (EB) formation as the first step of lineage restriction to mimic early human embryogenesis, which is then followed by manual selection of neuroepithelial precursors. This procedure is tedious and often inconsistent. We have developed a novel neural differentiation scheme that directs human iPSCs (created with the Allele 6F mRNA reprogramming kit) that progressed, as attached culture, to neural precursor cells (NPCs) in just 4-6 days, half the time it typically takes by other methods. From NPCs it takes about another 5-6 days for neural rosettes to form (see figures below); upon passage, cells in neural rosettes differentiate into neurons in 24 hours.

The neural progenitors at the rosettes stage can be stocked and expanded, before differentiated into different types of neurons. We are working on specifically and efficiently different these neural progenitor cells into dopaminergic, glutamatergic, GABAergic, and other types of sub-types of neurons with Allele’s technologies (Questions? email the Allele Stem Cell Group at iPSatAllelebiotech.com).

Neural rosettes formed efficiently in wells without going through EB.

neural rosettes formed as attached cells in less than 2 weeks

Human iPSC-derived neurons are created in a short regimen developed at Allele Biotech

Neurons appear from precursor cells shortly after the rosette stage

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Wednesday, February 5th, 2014 iPSCs and other stem cells, Open Forum No Comments