Exploiting the features of short peptides to recognize specific cell surface markers

Stem cells have an unlimited potential for cell division and the ability to transdifferentiate into other cell types.In recent years they grew to be a first-line weapon of regenerative medicine for repairing tissue and organic abnormalities caused by diseases, congenital deficiencies, and age-related effects 1 .Bone marrow-derived mesenchymal stem cells (MSCs) mainly develop in adipocytes, chondroblasts, and osteoblasts but also show the property to successfully transdifferentiate in neural, myocyte, and epidermal cells when engrafted in endogenous tissues under specific conditions 2 .Efficient isolation of MSCs from other cell components in the bone marrow is fundamental to obtaining valuable MSC clinical applications.Currently, the most widespread purification methods include the isolation of MSCs based on the expression of precise surface markers, thus involving specific antibodies 3 .In this work, we aimed to develop a fast and affordable method for the phenotypic characterization and isolation of MSCs from bone marrow without using immunoglobulins.To this purpose, we designed short peptides based on the deposited 3D structures of two specific MSCs surface markers, CD44 and CD271, in complex with their natural ligands.The peptides were selected by computational modeling, synthesized by solid-phase peptide synthesis, and tested in cell assays.Interestingly the data show that starting from a small set of peptides, using a protocol based on molecular simulations, it is possible to obtain small ligands endowed with a significant specificity in targeting CD44 and CD271 in place of their antibody, bypassing the common challenges and issues due to the use of immunoglobulins. Conclusions.In this poster, we report a methodology for the use of short peptide sequences as a tool for phenotypic characterization and the isolation of cell bodies, exploiting their binding of surface cell markers.Taken together, the data show that using an ad hoc designed computational protocol, it is possible to obtain short peptide sequences with adequate specificity to study the expression of the CD44 and CD271 receptors by an antibody-free assay.Replacing antibodies with short peptides can be a viable strategy in all procedures that require the use of antibodies to preserve sensitivity and specificity while avoiding high costs and complex laboratory protocols.This work paves the way towards the identification of a range of peptide aptamers targeting biomarkers relevant to existing or emerging biomedical applications such as regenerative medicine.In the latter case, the availability of these aptamers will enable the selection of specific cell populations suitable for tissue regeneration as such or in combination with nanoparticles.