Department of Agriculture, Utsunomiya University, Tochigi, Japan.
Exp Hematol. 2012 Jun;40(6):436-44. doi: 10.1016/j.exphem.2012.01.018. Epub 2012 Feb 2.
In utero transplantation (IUT) of human hematopoietic stem cells has been conducted in sheep, which are used as large animal models of human hematopoietic reconstitution and models for clinical IUT; however, the levels of engraftment have generally been low. Busulfan (BU), a myeloablative agent, is often administered to patients before hematopoietic stem cells transplantation to improve the engraftment. In this study, hematopoietic activity was evaluated in adult sheep after administering BU at different doses. Next, pregnant ewes were administered BU, and dams as well as their fetuses were evaluated, as BU readily crosses the sheep placenta. Then, the BU dose with the desired outcomes was selected and administered to pregnant ewes at 2 or 6 days before performing IUT using human cord blood CD34(+) cells. The engraftment was evaluated in recipients that underwent IUT in the presence or absence of BU. As a result, hematopoietic activity was safely and transiently suppressed in adult sheep treated with 5 to 7.5 mg/kg BU. BU crossed the sheep placenta, and fetal sheep were indeed conditioned by administering 3 mg/kg BU to pregnant ewes. Engraftment of human CD34(+) cells in fetal recipients was enhanced when IUT was carried out 6 days post-BU. Up to 3.3% engraftment levels (in terms of bone marrow colony-forming units) were achieved with the IUT of 0.72 to 2.4 million CD34(+) cells when BU was used. BU can be administered to pregnant ewes to effectively condition the fetal recipient for IUT with enhanced engraftment of donor cells.
体内人造血干细胞移植（IUT）已在绵羊中进行，绵羊被用作人类造血重建的大动物模型和临床 IUT 模型；然而，植入水平通常较低。白消安（BU）是一种骨髓清除剂，常被用于造血干细胞移植前以提高植入率。在这项研究中，在不同剂量下给予 BU 后评估成年绵羊的造血活性。接下来，对怀孕母羊给予 BU，并评估母羊及其胎儿，因为 BU 很容易穿过绵羊胎盘。然后，选择具有所需结果的 BU 剂量，并在进行 IUT 之前 2 或 6 天给予怀孕母羊，使用人脐带血 CD34(+)细胞。在存在或不存在 BU 的情况下，评估接受 IUT 的受者的植入情况。结果，5 至 7.5mg/kg BU 治疗的成年绵羊的造血活性被安全且短暂地抑制。BU 穿过绵羊胎盘，并且当向怀孕母羊给予 3mg/kg BU 时，胎儿绵羊确实被调理。当在 BU 后 6 天进行 IUT 时，增强了胎儿受者中人 CD34(+)细胞的植入。当使用 BU 时，通过 IUT 输注 0.72 至 240 万个 CD34(+)细胞，可达到高达 3.3%的植入水平（以骨髓集落形成单位表示）。可以向怀孕母羊给予 BU，以有效调理胎儿受者，从而增强供体细胞的植入。
