Isolation of FRET-positive cells using single 408-nm laser flow cytometry.

Background: Flow cytometry may be used to isolate large amounts of living, fluorescently labeled cells. Certain fluorescent labels, like enhanced cyan fluorescent protein (ECFP) and enhanced yellow fluorescent protein (EYFP), allow the assessment of direct protein-protein interaction in situ, by fluorescence resonance energy transfer (FRET). However, current flow cytometric methods either require elaborate technical adaptations or, using a single laser protocol, are hampered by background signal.

Programmed cell death is an intrinsic feature of MDS progenitors, predominantly found in the cluster-forming cells.

Objective: Bone marrows (BM) of myelodysplastic syndrome (MDS) patients show increased proliferation and premature programmed cell death (PCD) in vivo as well as in vitro. We explored the proliferative capacity and apoptotic propensity of CD34+ progenitor cells of MDS patients excluding accessory cell interference.

Materials And Methods: CD34+/CD3-/CD19- cells of 5 MDS patients and 5 normal BM were sorted as single cells into single wells and were cultured in liquid medium.

Regulation of LFA-1 Expression by CD34 Positive Cells and Inducible Growth Factor Production by Stroma Enable Formation of Bone Marrow Compartments; Subject Heading.

Leukocyte function associated antigen 1 (LFA-1) is an adhesion molecule indispensable in immune and inflammatory reactions, but its role in hematopoiesis is poorly understood. LFA-1 is considered as a marker of late stage stem cell maturation when expressed on CD34(+) bone marrow cells. We observed that CD34(+) bone marrow cells express LFA-1, that based on LFA-1 expression several subpopulations can be distinguished, and that the level of expression appeared highly variable among different donors.