Production of mesenchymal tumors in nude mice by Ph1 negative fibroblasts obtained from a Ph 1 positive CML patient: a preliminary report.

An experimental model system is presented for the investigation in humans of the role of hematopoietic stromal elements in the regulation of hematopoiesis as well as in the pathogenesis of myelofibrosis in myeloproliferative disorders. The model is based on the simultaneous application of three experimental techniques: (1) growth of bone-marrow derived fibroblastic colonies in vitro, (2) cytogenetic demonstration of marker chromosomes associated with hematopoietic malignancies, and (3) the transplantation of isolated stromal elements into athymic (nude) mice. Using this model, we describe the induction of mesenchymal tumors in nude mice by Ph1 negative fibroblasts obtained from the bone marrow of a patient with a Ph1 positive chronic myelogenous leukemia. Mesenchymal tumors also were induced in nude mice with bone marrow-derived fibroblasts from a patient with aplastic anemia, who was successfully treated with bone marrow transplantation, and from a normal human volunteer. Morphologic, cytogenetic and electron microscopic studies of bone marrow mesenchymal elements in culture and of tumors induced in nude mice from the CML patient indicate the cells composing the tumor are of human origin and are negative for the Ph1 chromosome. The results provide the first in vivo morphological and cytogenetic support using human materials, of the hypothesized relationship of progenitors of in vitro fibroblastic colonies to marrow stromal elements.