Shatry Alwi M, Jones Monica, Levy Robert B
Department of Microbiology, University of Miami School of Medicine, Miami, FL 33101, USA.
Stem Cells Dev. 2004 Feb;13(1):51-62. doi: 10.1089/154732804773099254.
These studies investigate the involvement of the spleen in progenitor (PC) cell numbers and "cross-talk" with the marrow compartment following syngeneic or allogeneic bone marrow transplantation (BMT) in sham or fully splenectomized mice. Intact recipient B6 mice were lethally irradiated prior to transplant with T cell-depleted bone marrow (BM-TCD). The kinetics of PC reconstitution following i.v. transplant consistently revealed a dramatic increase in splenic colony-forming unit interleukin-3 (CFU IL-3) and CFU (high proliferative potential-(HPP) levels between days 5 and 12 post-BMT. Direct injection of TCD-BM into the recipient marrow cavity did not alter this pattern of reconstitution in the splenic compartment. In contrast to spleens from normal adult B6 mice containing 0.9% and 0.6% of the total combined splenic and marrow committed (CFU IL-3) and primitive (CFU-HPP) progenitors, respectively, spleens of syngeneic BMT recipients at day 12 contained a 10-fold increase (p < 0.001) over the progenitor levels in normal spleens. These splenic numbers decreased to normal, homeostatic levels by day 28 post-BMT. In contrast, the level of marrow CFU IL-3 progenitors continued to increase post-transplant, reaching near homeostatic levels by day 28 post-BMT. Interestingly, early seeding of 5- (and -6)carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled or green fluorescent protein (GFP) donor bone marrow cells (BMC) to the marrow compartment was not different in sham splenectomies or recipients splenectomized 14 days earlier. However, recipient splenectomy consistently resulted in significantly higher numbers of CFU IL-3 in the bone marrow during the first 2 weeks post-transplant compared to sham controls. These elevated levels exceeded the combined progenitor numbers of the splenic and marrow compartments of intact recipients. Notably, this increase in marrow progenitor activity in splenectomized recipients was observed after syngeneic as well as allogeneic BMT. Allogeneic transplants across major, or those limited to minor, histocompatibility antigen differences exhibited this increased marrow progenitor activity. Splenectomy performed 2 h post-transplant to assure "normal" marrow seeding also resulted in higher marrow progenitor activity. Thus, this "marrow response" to splenectomy is not induced by early "shunting" of infused BM cells to the marrow compartment. These results suggest that communication between the splenic and marrow compartments following syngeneic and allogeneic BMT exists during early hematopoietic reconstitution, one effect of which is to impact the compartmental distribution of donor progenitor cells. The role of the spleen on engraftment, chimerism, and tolerance in allogeneic BMT models are now under investigation.
这些研究调查了在假手术或完全脾切除的小鼠中，同基因或异基因骨髓移植（BMT）后脾脏在祖细胞（PC）数量方面的作用以及与骨髓腔的“相互作用”。完整的受体B6小鼠在移植前接受致死剂量的照射，然后移植去除T细胞的骨髓（BM-TCD）。静脉注射移植后PC重建的动力学一致显示，在BMT后第5天至12天之间，脾集落形成单位白细胞介素-3（CFU IL-3）和CFU（高增殖潜能 - （HPP）水平显著增加。将TCD-BM直接注射到受体骨髓腔中并没有改变脾脏区室的这种重建模式。与正常成年B6小鼠的脾脏分别含有总联合脾脏和骨髓定向（CFU IL-3）和原始（CFU-HPP）祖细胞的0.9%和0.6%相比，同基因BMT受体在第12天的脾脏中祖细胞水平比正常脾脏增加了10倍（p < 0.001）。这些脾脏中的数量在BMT后第28天降至正常的稳态水平。相比之下，骨髓CFU IL-3祖细胞的水平在移植后继续增加，并在BMT后第28天达到接近稳态水平。有趣的是，将5 - （和 -6）羧基荧光素二乙酸琥珀酰亚胺酯（CFSE）标记或绿色荧光蛋白（GFP）供体骨髓细胞（BMC）早期接种到骨髓腔中，在假脾切除或提前14天脾切除的受体中没有差异。然而，与假手术对照组相比，受体脾切除在移植后的前2周内始终导致骨髓中CFU IL-3的数量显著增加。这些升高的水平超过了完整受体脾脏和骨髓区室联合祖细胞的数量。值得注意的是，在同基因以及异基因BMT后，在脾切除的受体中都观察到了骨髓祖细胞活性的增加。跨越主要组织相容性抗原差异或仅限于次要组织相容性抗原差异的异基因移植都表现出这种骨髓祖细胞活性的增加。在移植后2小时进行脾切除以确保“正常”的骨髓植入也导致了更高的骨髓祖细胞活性。因此，这种对脾切除的“骨髓反应”不是由注入的BM细胞早期“分流”到骨髓腔引起的。这些结果表明，在同基因和异基因BMT后的早期造血重建过程中，脾脏和骨髓区室之间存在相互作用，其作用之一是影响供体祖细胞的区室分布。目前正在研究脾脏在异基因BMT模型中的植入、嵌合体形成和耐受性方面的作用。
