Blood, Vol. 93 No. 2 (January 15), 1999:
pp. 746-755
Proliferation and Survival of Mammary Carcinoma Cells Are Influenced
by Culture Conditions Used for Ex Vivo Expansion of CD34+
Blood Progenitor Cells
A. Spyridonidis,
W. Bernhardt,
D. Behringer,
G. Köhler,
M. Azemar,
A. Pflug, and
R. Henschler
From the Experimental Hematology Group, the Department of Hematology,
and the Department of Pathology, Freiburg University Medical Center,
Freiburg, Germany; and the Institute for Experimental Cancer Research,
Tumor Biology Center, Freiburg, Germany.
Malignant cell contamination in autologous transplants is a
potential origin of tumor relapse. Ex vivo expansion of
CD34+ blood progenitor cells (BPC) has been proposed as a
tool to eliminate tumor cells from autografts. To characterize the
influence of culture conditions on survival, growth, and clonogenicity
of malignant cells, we isolated primary mammary carcinoma cells from
pleural effusions and ascites of patients with metastatic breast cancer and cultured them in the presence of stem cell factor (SCF),
interleukin-1
(IL-1), IL-3, IL-6, and erythropoietin (EPO), ie,
conditions previously shown to allow efficient ex vivo expansion of
CD34+ BPC. In the presence of serum, tumor cells
proliferated during a 7-day culture period and no significant
growth-modulatory effect was attributable to the presence of
hematopoietic growth factors. When transforming growth factor-1
(TGF-1) was added to these cultures, proliferation of
breast cancer cells was reduced. Expansion of clonogenic tumor cells
was seen in the presence of SCF + IL-1 + IL-3 + IL-6 + EPO,
but was suppressed by TGF-1. Cocultures of tumor cells in direct
cellular contact with hematopoietic cells showed that tumor cell growth
could be stimulated by ex vivo expanded hematopoietic cells at high
cell densities (5 × 105/mL). In contrast, culture under
serum-free conditions resulted in death of greater than 90% of breast
cancer cells within 7 days and a further decrease in tumor cell numbers
thereafter. In the serum-free cultures, hematopoietic cytokines and
cellular contact with CD34+ BPC could not protect the
tumor cells from death. Therefore, ex vivo expansion of
CD34+ BPC in serum-free medium provides an environment
for efficient purging of contaminating mammary carcinoma cells. These
results have clinical significance for future protocols in autologous progenitor cell transplantation in cancer patients.
