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A liver-metastatic model of human primary gastric lymphoma in nude mice orthotopically constructed by using histologically intact patient specimens.

BACKGROUND AND OBJECTIVE
In recent years, incidence and mortality of lymphoma are markedly increasing worldwide. However, the pathogenesis and mechanism of invasion and metastasis for lymphoma are not yet fully clarified. It is mainly due to the lack of ideal animal models, which can precisely simulate the invasion and metastasis of lymphoma in the human body. So, it is very necessary to establish a highly metastatic nude mouse model of human lymphoma. This study developed a liver-metastatic model of primary gastric lymphoma in nude mice by using orthotopic surgical implantation of histologically intact patient specimens into the corresponding organs of the recipient small animals.


METHODS
A histologically intact fragment of liver metastasis derived from a surgical specimen of a patient with primary gastric lymphoma was implanted into the submucosa of the stomach in nude mice. Tumorigenicity, invasion, metastasis, morphologic characteristics (via light microscopy, electron microscopy, and immunohistochemistry), karyotype analysis, and DNA content of the orthotopically transplanted tumors were studied.


RESULTS
An orthotopic liver metastatic model of human primary gastric lymphoma in nude mice (termed HGBL-0304) was successfully established. The histopathology of the transplanted tumors showed primary gastric diffuse large B-cell lymphoma. CD19, CD20, CD22, and CD79alpha were positive, but CD3 and CD7 were negative. The serum level of lactate dehydrogenase (LDH) was elevated [(1010.56+/-200.85) U/L]. The number of chromosomes ranged from 75 to 89. The DNA index (DI) was 1.45+/-0.25 (that is, heteroploid). So far, the HGBL-0304 model has been passed on for 45 generations of nude mice. A total of 263 nude mice were used for the transplantation. Both the growth and resuscitation rates of liquid nitrogen cryopreservation of the transplanted tumors were 100%. The transplanted tumors autonomically invasively grew and damaged a whole layer in the stomach of nude mice. The metastasis rates of liver, spleen, lymph node, and peritoneal seeding were 100%, 94.3%, 62.6%, and 43.5%, respectively.


CONCLUSIONS
The study successfully establishes an orthotopic liver metastatic model of human primary gastric lymphoma in nude mice. The HGBL-0304 model can completely simulate the natural clinical process of primary gastric lymphoma and provides an ideal animal model for the research on the biology of metastasis and antimetastatic experimental therapies of primary gastric lymphoma.