Schmidt Ruppin-D—avian sarcoma virus誘発ラット脳腫瘍モデル—組織像と治療スクリーニングにおける意義

SCHMIDT RUPPIN-D-ASV-INDUCED PRIMARY RAT BRAIN TUMOR MODEL FOR THERAPEUTIC SCREENING

　抄録　悪性脳腫瘍に対する新たな治療法を始めるにあたつて，臨床応用の前に動物モデルにおいて効果，副作用を評価量することが不可欠である。従来動物モデルとしては，C₆，9Lといつた移植腫瘍より自然発生腫瘍の方が好ましいといわれているが，このような腫瘍は稀であり，現実に利用できる段階ではない。そこで次善の動物モデルとして，infectious cell free homogeneous subgroup D Schmidt—Ruppin avian sarco—ma virus （SR-D—ASV）を新生児フィッシャーラット頭蓋内に接種し，脳腫瘍誘発を試み，腫瘍誘発率，生存曲線，誘発脳腫瘍の病理組織につき検討した。生後3日目フィッシャーラットにASV 2×10⁶FFU／5μlを接種すると，接種後20日目に小さな腫瘍が発生し，40日〜50日目にかけ急速に増大し平均生存日数は58.7±12日であつた。腫瘍は接種ラットの100％に発生した。誘発腫瘍組織像を大きく3つのカテゴリーに分類すると，astrocytoma 70.6％（protoplasmic 23.5％，fibrillary 47.1％），sarcoma 17.6％，mixed astro—cytoma＆sarcoma 11.8％であつた。このようにSR-D—ASV誘発脳腫瘍モデルは100％に誘発量可能であり，70％以上がグリアより発生し，脳実質内で増大し，平均58日という適当な期間内に全部死亡するという条件をみたす優れた実験モデルと考えられる。

It is important to evaluate the therapeutic and side effects of new therapy for malignant brain tumors in an adequate animal model prior to its initial clinical investigation. For decades, neurooncologists have argued for the use of primary, autochthonous tumors rather than transplanted tumors such as C 6 glioma cells and 9 L gliosarcoma cells. But un-fortunately, no spontaneous animal astrocytomas are currently available as usable models. So we tried to establish the model of primary, auto-chthonous avian sarcoma virus-induced rat gliomas for experimental chemotherapy and immunotherapy. The present study was undertaken to determine the incidence and histologic pattern of tumors and the mean survival time of the animal model used.It was found that the intracerebral inoculation of 2×10⁶ FFU/5μl of infectious cell free homogeneous subgroup D Schmidt-Ruppin avian sarcoma virus (SR-D-ASV) into 3-day-old inbred Fischer 344 rats induced small sized tumors in all rats 20 days later. The mean survival time of inoculated rats were 58.7±12 days. As to the classification of SR-D-ASV induced brain tumors in Fischer rats, astro-cytoma was 70. 6% (protoplasmic astrocytoma 23. 5 %, fibrillary astrocytoma 47. 1%), sarcoma 17. 6%, and mixed astrocytoma and sarcoma 11.8%. In conclusion, this SR-D-ASV induced tumor in the rat fulfilled the following criteria for the desirable animal model:(1) Spontaneously arising. (2) Glial origin. (3) Intraparenchymal growth. (4) Uni-formly fatal within reasonable time period. Statis-tic evaluation of the effects of chemotherapy and immunotherapy was considered to be possible.