Busulfan is the most commonly used drug for preconditioning during the transplantation of hematopoietic stem cells and male germ cells. Here, we describe side effects of high doses of busulfan in male mongrel dogs. Busulfan was intravenously administered to three groups of dogs at doses of 10, 15, and 17.5 mg/kg body weight. The total white blood cell, neutrophil, eosinophil, lymphocyte, monocyte, and platelet counts steadily reduced in a dose-dependent manner following busulfan treatment. The white blood cell, neutrophil, and monocyte counts recovered after 6 weeks of busulfan treatment, however, the eosinophil, lymphocyte, and platelet counts remained unaltered. Additionally, there was one fatality in the each of the groups that were administered 15 and 17.5 mg/kg busulfan. The gross lesions included severe hemorrhage in the stomach, intestinal tracts, mesentery and urinary bladder. Microscopic investigation revealed severe pulmonary edema and hemorrhage in the lungs, and severe multifocal to coalescing transmural hemorrhage in the intestines and urinary bladder. These results indicated that treatment with busulfan at doses higher than 15 mg/kg initiates severe bleeding in the internal organs and can have fatal results.

Accumulating evidence suggests that chemotherapy can cause long‐term detrimental effects and alter the biology of the recipient environment. Therefore, a subsequent report claimed that the transplantation of female germline stem cells (FGSCs) into the ovaries of recipient mice that were pretreated with a high dose of busulfan and cyclophosphamide (B/C) resulted in the successful production of offspring. Therefore, this study was conducted to further clarify the impact of female germ cell transplantation on female ovaries after B/C treatment. RT‐PCR analysis showed that the period of germ cell depletion coincide with decreased Figla, Lhx8, Nobox, Kit, and Sox3 gene expression in the B/Ctreated ovary. However, depletion of female germ cells is mediated by a Fas/FasL‐, Kit/ Kitl‐, TNF‐, p53‐ and autophagy‐ independent pathway. Also, histological analysis is similar to that of Nobox null‐derived ovaries, indicating that follicle death after B/C treatment might be caused by down‐regulating of Nobox pathway. When female mice during 15 weeks after B/C treatment were checked for reproductive activity, B/C treated mice did not produce their pups. In addition, when 3×106 GFP positive primordial follicles were injected into B/C treated female mouse ovaries, donor follicle were not able to colonize into the ovaries of recipients. In conclusion, these data from a preclinical mouse model strongly suggested that female ovary until 15 weeks after B/C treatment could not support environment for maturing of exogenous FGSCs.

Identification of spermatogonial stem cell-specific surface molecules is important in understanding the molecular mechanisms underlying the maintenance and differentiation of these cells. We have found that spermatogonia from busulfan treated mice expressed an autoantigen that distinguishes between undifferentiated and differentiated spermatogonia. Four to six weeks after busulfan treatment, germ cells located in the basal compartment of seminiferous epithelium show isotype-specific IgG deposits that form due to autoimmunity. Before busulfan treatment, the level of testicular IgG was very low but IgG levels began to increase after week 4 and peaked at week 6. When cells from the busulfan treated testis were analyzed using laser scanning cytomeoy (LSC), the frequency of cells positive for IgG deposits, 6-integrin, and 1-integrin were 16.53.8%, 11.82.6%, and 9.0 1.4%, respectively. Immunofluorescent staining suggested that most, if not all of the cells with IgG-deposits isolated from a laminin-coated dish, were also positive for a spermatogonial stem cell marker \ulcorner6-integrins as well as for a germ cell-specific marker TRA 98. We determined serum and intratesticular IgG levels and the soundness of seminiferous tubule basement membrane from busulfan treated mice using electron microscopy, in order to study the mechanism responsible for IgG deposits in spermatogonia. We found that the basement membranes of seminiferous tubules from busulfan treated mice were severely impaired when compared to those of normal adult, neonates and w/wv mice. Furthermore, new blood cells were observed in the surface of the damaged basement membrane along the seminiferous tubules. These results suggest that the IgG in spermatogonial stem cells accumulates from circulating blood through the impaired basement membranes induced by busulfan treatment. Taken together, our study suggests that IgG can be used as a new marker for undifferentiated spermatogonia cells.

본 연구는 생식선 키메라 생산효율을 높이기 위한 방법으로 busulfan 가온 주입법을 이용하여 효과적인 원시생식 세포의 이동능력을 검증하였다. 효율적인 생식선 키메라 닭 생산에서 중요한 요건 중 하나인 공여체 원시생식세포의 생존율을 측정한 실험에서는 시간이 지남에 따라 생존율에 변화를 보였으나, 평균 을 유지하고 있었으며, busulfan 처리 유무에 따른 공여체 원시생식세포 이동능력은 형광염색 후 주입한 실험에서 대조구가 4.8%인 반면 실험구는 2