Serial booster transplants separated by brief intervals has been shown to enhance the engraftment levels in syngeneic postnatal models without myeloblation. Additionally, the prenatal transplantation of allogeneic marrow has been shown to result in long-term donorspecific tolerance. From these two observations, we hypothesized that serial booster transplants can enhance the engraftment of allogeneic marrow following in utero hematopoietic stem cell transplantation (lUHSCTx). To test this hypothesis we performed multiple transplants in an allogeneic murine strain combination with a congenic strain combination used as a naturally tolerant control. B6Pep3b(//2 , CD45.1) and SJL/J ( H2l CD45.1) were used as donors of adult marrow and C57B1/6 (H2h, CD45.2) were used as 14 day gestation fetal recipients. Adult marrow of both donor strains was subjected to CD3+ T cell magnetic bead depletion to eliminate the possibility of GVHD. All fetuses were injected intraperitoneally with 106 mononuclear cells. Boosted neonates were injected at days 2, 4, and 7 of life with 5xl06 cells. All animals were analyzed forperpheral blood chimerism by dual color flow cytometry for the isoforms of CD45. Data is presented from three groups of animals at 6 months of age: 1) recipients of lUHSCTx-only; 2) recipients of post-natal booster transplants only; and 3) recipients of combined lUHSCTx and post-natal booster transplantation. No significant difference was seen between the congenic (n=7) or allogeneic (n=4) lUHSCTx-only groups (0.54+0.35 vs. 0.37±0.24, p=0.36). Similar levels were also seen between the congenic (n=8) and allogenic (n=6) recipients of combined lUHSCTx and post-natal booster transplants (4.1±1.87 vs. 3.35±2.32, p=0.53). However, recipients of congenic post-natal transplants (n=8)only demonstrated significantly higher levels of donor cell engraftment than their allogeneic counterparts (n=6) (2.44±0.85 vs. 0.10±0.02, rxO.OOOl ). No evidence of GVHD was seen in any of the groups. From these results we conclude: 1) post-natal booster transplantation following lUHSCTx can achieve higher levels of engraftment similar to those levels in naturally tolerant strain combinations; and 2) in order to be successful, the allogeneic postnatal transplants require the tolerizing effect of a prenatal transplant. These studies establish that lUHSCTx can indeed facilitate successful allogeneic postnatal booster transplantation. Further studies with more aggressive postnatal regimens in this model are critical to achieving the higher levels of chimerism needed to treat diseases such as thalassemia or sickle cell anemia.
|Original language||English (US)|
|Issue number||11 PART II|
|State||Published - Dec 1 2000|
ASJC Scopus subject areas
- Cell Biology