Medizinische Universitätsklinik
Innere Medizin II
Hämatologie, Onkologie, klinische Immunologie und Rheumatologie

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Adresse: Otfried-Müller-Straße 10
72076 Tübingen


Personenprofil: 07071 29-82711 Pforte


Telefonnummer: 07071 29-89200 24h Hotline


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Für akute Notfälle


Labor für Stammzellforschung

Identification and characterization of rare stem cell populations

To identify rare hematopoietic, mesenchymal, epithelial, and spermatogonial stem cell populations, monoclonal antibodies are used and/or raised against cell surface antigens that are expressed with high selectivity on these cells. Rare cells are defined by a population size of <1% in a heterogeneous cell mixture. Magnetic activated cell sorting (MACS) and/or fluorescence activated cell sorting (FACS) techniques are used to isolate these cells, The sorted cells are analyzed for their morphology, immunophenotype, proliferation (expansion) and differentiation potential (colony assays, phenotypic and functional analysis of differentiated cells).

Kontakt

Arbeitsgruppenleiter

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CD271+TNAP++ BM-MSC

 

  

Identification of new cell surface antigens defined by monoclonal antibodies

A major research interest is to identify the membrane antigens recognized by novel monoclonal antibodies. For this purpose, we use several strategies.

  • Affinity purification of cell lysates derived from positive cell lines. The lysates are then separated by SDS-PAGE and subjected to fingerprint or partial amino acid analysis.
  • Screening of the antibodies on retroviral expression libraries. Positive cells are cloned, the integrated cDNA isolated and sequenced.
  • Screening of the antibodies on available transfectant lines that express known and promising antigens on the cell surface.

Using these strategies we identified the following human cell surface antigens:

Cell Surface antigens
CD10 (Neutral endopeptidase) CD105 (endoglin) CD167a (discoidin receptor 1) CD340 (HER2)
CD13 (Aminopeptidase N) CD109 CD172a (SIRPα) CD344 (frizzled-4)
CD15 (Lewis X, X-Hapten) CD117 (c-kit) CD172b (SIRPβ) CD349 (frizzled-9)  
CD18 (ß2-Integrin) CD133 (prominin) CD203c (E-NPP3) HER3  
CD19 (Bgp95, B4) CD135 (FLT3) CD276 δ-opioid receptor
CD33 (MY9, Siglec3) CD140a (PDGF-RA) CD318 (CDCP1) LAR protein  
CD34 (My10, gp105-120) CD140b (PDGF-RB) CD324 (E-cadherin) TNAP  
CD47 (Integrin-associated protein) CD164 (endolyn) CD326 (Ep-CAM) SSEA-4  
    CD334 (FGFR-4) SUSD2  

and several other antibody-defined antigens selectively expressed on the surface of rare cell subsets.

Identification of new extracellular ligands

An additional research interest is the identification of membrane-bound ligands of membrane molecules. For this purpose, we perform cell attachment assays with recombinant proteins resembling the extracellular domains of the receptor. A binding cell line will be used to prepare cell lysates that will be affinity-purified on immobilized receptors. The purified ligand will then be subjected to fingerprint analysis. Using a modified strategy, we identified human SIRPα1 and SIRPα2 to be receptors for CD47. In contrast, SIRPβ1 did not bind to CD47.

Clustering of novel antibodies in HCDM (previously HLDA) workshops

During the past Conferences on Human Leukocyte Differentiation Antigens (HLDA) and Human Cell Differentiation Molecules (HCDM), several antibodies from our group were clustered (CD nomenclature). Novel antibodies are expected to be clustered In the forthcoming HCDM/HLDA conferences.

Collaborations

  • Prof. Dr. med. Handretinger

  

Grants

  • DFG-Projekt: Beteiligung einer CD56+ mesenchymalen Stammzellpopulation an der humanen hämatopoetischen Stammzellnische in unterschiedlichen Knochenkompartimenten (eingereicht).



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