Stem cell activity of porcine c-kit+ hematopoietic cells.
OBJECTIVE
A marker for hematopoietic stem cells (HSCs) of pigs, which are considered to be the most suitable donors for clinical xenotransplantation, has not yet been identified. In this study, we examined the HSC activity of porcine c-kit+ bone marrow cells (BMCs).


METHODS
The HSC activity of porcine c-kit+ BMCs was evaluated both in vitro using colony-forming unit (CFU) and cobblestone area-forming cell (CAFC) assays and in vivo in nonobese diabetic/severe combined immunodeficiency transgenic (NOD/SCID-Tg) mice carrying porcine cytokine transgenes.


RESULTS
Purified c-kit+ BMCs were substantially enriched for both CFUs and CAFCs in vitro and their transplantation led to long-term porcine hematopoiesis in vivo in mice. Although porcine chimerism was detectable in the peripheral blood of NOD/SCID-Tg mice receiving porcine c-kit- BMCs at early time points after transplantation, the levels were markedly lower than those in mice receiving purified c-kit+ BMCs (0.2%+/-0.14% vs 7.7%+/-1.6% and 0.17%+/-0.17% vs 5.6%+/-2.1% at weeks 3 and 6, respectively). Importantly, all mouse recipients of porcine c-kit+ BMCs showed durable multilineage chimerism (>19 weeks), whereas no recipients of porcine c-kit- BMCs sustained long-term engraftment. Moreover, porcine HSCs that had engrafted for 19 weeks in the recipients of porcine c-kit+ BMCs gave rise to clonogenic progenitors in vitro and reconstituted porcine hematopoiesis in secondary recipients.


CONCLUSIONS
The present study demonstrates that c-kit is an essential marker of both long-term-repopulating HSCs and progenitor cells with early engraftment capacity.
Le Guern
Annie C
AC
BioTransplant, Incorporated, Charlestown, Mass., USA.
Giovino
Maria A
MA
Abe
Masahiro
M
Theodore
Pierre R
PR
Qi
Jin
J
Down
Julian D
JD
Sachs
David H
DH
Sykes
Megan
M
Yang
Yong-Guang
YG
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000502:physiology; D003114:Colony-Forming Units Assay; D006085:Graft Survival; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D019009:Proto-Oncogene Proteins c-kit / Q000502:physiology; D033581:Stem Cell Transplantation; D013552:Swine; D014183:Transplantation, Heterologous
D019009:Proto-Oncogene Proteins c-kit