title: Horizontal gene transfer from human endothelial cells to rat cardiomyocytes after intracoronary transplantation.
abstract: OBJECTIVE
  Recent studies suggested that human umbilical vein endothelial cells (HUVECs) transdifferentiate into cardiomyocytes and smooth muscle cells in vitro. To test the functional relevance of this observation, we examined the transdifferentiation potential of HUVECs in vivo after intracoronary cell application in Wistar rats.
  
  
  RESULTS
  SPECT measurements (single photon emission computed tomography) revealed that 18% of (111)In-labelled HUVECs infused by intracoronary delivery stably transplanted to the rat heart. For long-term tracking, HUVECs-expressing enhanced green fluorescent protein (EGFP) were infused. Two days following transplantation, HUVECs were positive for caspase-3. Within 3 days, EGFP was associated with individual cardiomyocytes. No labelling of endothelial and smooth muscle cells was observed. The total number of EGFP-labelled cardiomyocytes accounted for 58% of all initially trapped cells. These EGFP positive cells stained negatively for human mitochondrial proteins, but were positive for rat monocarboxylate transporter-1 protein (MCT-1). Furthermore, EGFP-mRNA was detected in these cells by single-cell RT-PCR (reverse transcription followed by polymerase chain reaction). After 21 days, EGFP positive cells were no longer observed. To investigate the underlying mechanism, we generated in vitro apoptotic bodies from EGFP-labelled HUVECs and found them to contain the genetic information for EGFP. Co-incubation of apoptotic bodies with neonatal rat cardiomyocytes caused cardiomyocytes to express EGFP.
  
  
  CONCLUSIONS
  When transplanted into the rat heart by efficient intracoronary delivery, EGFP-expressing HUVECs cause the exclusive but transient labelling of cardiomyocytes. Our in vivo findings suggest that it is not cell fusion and/or transdifferentiation that occurs under these conditions but rather a horizontal gene transfer of the EGFP marker via apoptotic bodies from endothelial cells to cardiomyocytes.
authors.affiliation: Institute for Heart and Circulatory Physiology, Heinrich Heine University Duesseldorf, Universitaetsstr. 1, 40225 Duesseldorf, Germany. sandra.burghoff@uni-duesseldorf.de
authors.forename: Sandra
authors.initials: S
authors.lastname: Burghoff
authors.forename: Zhaoping
authors.initials: Z
authors.lastname: Ding
authors.forename: Stefanie
authors.initials: S
authors.lastname: Gödecke
authors.forename: Alexander
authors.initials: A
authors.lastname: Assmann
authors.forename: Andreas
authors.initials: A
authors.lastname: Wirrwar
authors.forename: Doris
authors.initials: D
authors.lastname: Buchholz
authors.forename: Olga
authors.initials: O
authors.lastname: Sergeeva
authors.forename: Cordula
authors.initials: C
authors.lastname: Leurs
authors.forename: Helmut
authors.initials: H
authors.lastname: Hanenberg
authors.forename: Hans-Wilhelm
authors.initials: HW
authors.lastname: Müller
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Bloch
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schrader
mesh_terms: D000818:Animals; D017209:Apoptosis; D002454:Cell Differentiation; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000637:transplantation*; D022761:Gene Transfer, Horizontal; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D008297:Male; D032383:Myocytes, Cardiac / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins