Working together, chemists and biologists will be able to develop methods that combine genetic and metabolic engineering to introduce a range of unnatural epitopes onto cells without the restrictions imposed by nature’s biosynthetic machinery and metabolic building blocks. Advances in these technologies will also produce new, multifaceted tactics for landscaping cell surfaces. The potential for these techniques is tremendous. As a professional cell surface engineering services provider, Creative Biolabs is capable of providing customer-satisfied cell surface-based metabolic conjugation services to global clients.Fig.1 Metabolic engineering for introducing unnatural functional groups into cell-surface glycans for the subsequent bioorthogonal reaction. (Bi, 2018)
Much of enzyme-mediated labeling requires some aspects of time-intensive genetic engineering for tagged substrates. The continued pursuit of imparting orthogonality without the use of genetic manipulation has ignited the field of metabolic engineering. It is now possible to create new cell-surface epitopes via the metabolic incorporation of unnatural precursors into plasma membrane components. Oligosaccharides are particularly amenable to this type of metabolic engineering since the enzymes and transport proteins in certain biosynthetic pathways are tolerant of unnatural substrates. Cells will take up monosaccharide analogs from the extracellular environment and process them into cell-surface glycoconjugates. In contrast, the pathways for protein biosynthesis are more restrictive, and only the most conservatively modified amino acids are accepted.
Metabolic labeling is particularly advantageous in engineering cell surface proteoglycans, as glycostructures in various forms compose a significant portion of the extracellular matrix and the rapid turnover of these structures ensures rapid metabolic incorporation. In this method, azides were installed on the cell surface using the synthetic azido sugar precursor N-azidoacetylmannosamine (Ac4GalNAz). The precursors were incorporated into mucin-type O-linked glycoproteins in Jurkat cells via the N-acetylgalactosamine (GalNAc) salvage pathway. After 3 days of incubation, the glycostructures were orthogonally labeled with biotinylated triarylphosphine via click-based Staudinger ligation to produce stable cell-surface adducts. This strategy was also used to manipulate cell-cell interactions on peripheral blood mononuclear cells (PBMCs) to achieve targeted apoptosis.
While most cell therapies rely on cell surface engineering in vitro followed by in vivo administration, metabolic engineering can label cells in vivo without ex vivo or in vitro interventions. In an elegant strategy used to selectively label cancel cells in vivo, taking advantage of the enhanced enzyme activity exhibited in cancerous cells, researchers utilized a caged Ac4ManAz that can be selectively cleaved by cancer-overexpressed enzymes. Once decorated with azide moieties, an active tissue targeting via anchored click chemistry (ATTACK) strategy was employed to deliver alkyne labeled dibenzocyclooctyne doxorubicin conjugate to cancer tissue via click chemistry. The ATTACK strategy was deemed effective against MDAMB-231 triple-negative breast cancer, LS174T colon cancer, and 4T1 metastatic breast cancer in mice. Substantially reduced toxicity on non-cancerous cells was also observed with the use of ATTACK therapy.
Fig.2 Tumor targeted metabolic labeling. (Abbina, 2018)
Committed to cell surface conjugation research over years, Creative Biolabs has accumulated strong foundations such as advanced facilities, the latest technologies, and a team of professional experts. With reliable foundations and extensive experience accumulated step-by-step during practice, we are confident in providing every customer with satisfying cell surface-based metabolic conjugation services.
As an industry-leading cell surface engineering services provider, Creative Biolabs is your best partner. If you are interested in cell surface-based metabolic conjugation services or other cell surface engineering services, please feel free to contact us for more information.
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