Chimerism of the transplanted heart.
BACKGROUND
Cases in which a male patient receives a heart from a female donor provide an unusual opportunity to test whether primitive cells translocate from the recipient to the graft and whether cells with the phenotypic characteristics of those of the recipient ultimately reside in the donor heart. The Y chromosome can be used to detect migrated undifferentiated cells expressing stem-cell antigens and to discriminate between primitive cells derived from the recipient and those derived from the donor.


METHODS
We examined samples from the atria of the recipient and the atria and ventricles of the graft by fluorescence in situ hybridization to determine whether Y chromosomes were present in eight hearts from female donors implanted into male patients. Primitive cells bearing Y chromosomes that expressed c-kit, MDR1, and Sca-1 were also investigated.


RESULTS
Myocytes, coronary arterioles, and capillaries that had a Y chromosome made up 7 to 10 percent of those in the donor hearts and were highly proliferative. As compared with the ventricles of control hearts, the ventricles of the transplanted hearts had markedly increased numbers of cells that were positive for c-kit, MDR1, or Sca-1. The number of primitive cells was higher in the atria of the hosts and the atria of the donor hearts than in the ventricles of the donor hearts, and 12 to 16 percent of these cells contained a Y chromosome. Undifferentiated cells were negative for markers of bone marrow origin. Progenitor cells expressing MEF2, GATA-4, and nestin (which identify the cells as myocytes) and Flk1 (which identifies the cells as endothelial cells) were identified.


CONCLUSIONS
Our results show a high level of cardiac chimerism caused by the migration of primitive cells from the recipient to the grafted heart. Putative stem cells and progenitor cells were identified in control myocardium and in increased numbers in transplanted hearts.
Quaini
Federico
F
Department of Medicine, New York Medical College, Valhalla 10595, USA.
Urbanek
Konrad
K
Beltrami
Antonio P
AP
Finato
Nicoletta
N
Beltrami
Carlo A
CA
Nadal-Ginard
Bernardo
B
Kajstura
Jan
J
Leri
Annarosa
A
Anversa
Piero
P
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis / Q000276:immunology; D000328:Adult; D000368:Aged; D000906:Antibodies / Q000032:analysis; D000950:Antigens, Ly / Q000032:analysis / Q000276:immunology; D016022:Case-Control Studies; D002455:Cell Division; D005260:Female; D006321:Heart / Q000502:physiology*; D016027:Heart Transplantation; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000032:analysis / Q000276:immunology; D008875:Middle Aged; D009206:Myocardium / Q000166:cytology*; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis / Q000276:immunology; D013234:Stem Cells / Q000502:physiology; D014019:Tissue Donors; D018183:Transplantation Chimera; D014998:Y Chromosome
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000906:Antibodies; D000950:Antigens, Ly; D008565:Membrane Proteins; D019009:Proto-Oncogene Proteins c-kit