Sortase-A mediated chemoenzymatic lipidation of single-domain antibodies for cell membrane engineering

Abstract

Purpose: Membrane engineering has versatile applications in adoptive cell therapies, immune therapy or drug delivery. Incorporation of lipidated antibody-derived ligands into cells may enforce supraphysiological cell interactions that offer new therapeutic approaches. A challenge is the defined synthesis of lipidated ligands that effectively interact with such membranes.

Methods: Sortase-A was used to attach a PEGylated, dimyristyl lipid-anchor on single-domain antibodies (VHH). The membrane insertion was investigated on liposomal bilayers, myeloid-derived suppressor cells (MDSC) and T cells.

Results: The lipidated VHHs remodeled liposomal as well as cellular membranes. The VHH carrying liposomes were successfully targeted towards antigen-positive cells. MDSC and T cells were both modified with lipidated VHHs as detected with an FITC-anti-llama antibody. T cells that carried an anti-CD11b VHH showed cellular association in vitro with CD11b⁺Gr-1⁺ MDSC in a two-dimensional magnetic activated cell sorting / flow-cytometry assay.

Conclusion: The applied combination of chemoenzymatic ligation, PEGylated lipid anchors and single-domain antibodies delivers water-soluble and chemically defined lipidated ligands, which readily associate with liposomal and cellular membranes. This enables liposomal drug targeting and artificial cell-cell interactions. Hence, the presented concept for lipidation of single-domain antibodies is promising for further application in the field of drug delivery or cell-based therapies.

Keywords: Cell membrane engineering; Cell therapy; Hydrophobic insertion; Liposomes; Single-domain antibodies; Sortagging; Sortase-A.