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Updated: Aug 2, 2026
A Novel Stromal Fibroblast-Modulated 3D Tumor Spheroid Model for Studying Tumor-Stroma Interaction and Drug Discovery
Published on: February 28, 2020
In vitro and in vivo studies of stromal niches
P J Quesenberry1, R B Crittenden, P Lowry
1Department of Medicine, University of Massachusetts Medical Center, Worcester.
Insights
Stromal cells in bone marrow produce essential cytokines like Steel factor, supporting hematopoietic stem cell growth and function. These stem cells show robust engraftment potential in normal hosts.
Area of Science:
- Hematology
- Stem Cell Biology
- Molecular Biology
Background:
- Lymphohematopoiesis occurs within the bone marrow's complex microenvironment.
- Primitive lymphohematopoietic stem cells interact closely with various supportive stromal cells.
Purpose of the Study:
- To investigate cytokine production by bone marrow stromal cells in vitro.
- To determine the role of specific cytokines in supporting hematopoietic stem cell function and engraftment.
Main Methods:
- Utilized an in vitro long-term Dexter liquid culture system.
- Analyzed cytokine production via Northern blot, bioassay, and reverse-transcriptase PCR.
- Assessed stem cell function using high proliferative potential colony-forming cell assays and transplantation models.
Main Results:
- Stromal cells constitutively produce Steel factor, IL-6, and CSF-1.
- Granulocyte-CSF and granulocyte-macrophage-CSF mRNA detected upon refeeding.
- Steel factor is crucial for synergistic cytokine combinations supporting stem cell proliferation and engraftment.
- Hematopoietic stem cells demonstrate high engraftment rates in normal hosts, but post-5-fluorouracil bone marrow shows deficient engraftment.
Conclusions:
- Bone marrow stromal cells are a key source of cytokines regulating lymphohematopoiesis.
- Steel factor plays a central role in supporting hematopoietic stem cell function and engraftment.
- Hematopoietic stem cell engraftment capacity is influenced by the bone marrow microenvironment and prior treatments.
Abstract:
Lymphohematopoiesis occurs in the densely packed environment of the intramedullary spaces. Primitive lymphohematopoietic stem cells exist in close apposition to a variety of supportive cells including both hemopoietic and nonhemopoietic lineages. Using an in vitro long-term Dexter liquid culture system, we have established that a variety of cytokines are produced constitutively by such stromal cells in culture. These cytokines include Steel factor, interleukin-6 (IL-6), and colony-stimulating factor (CSF-1). Granulocyte-CSF and granulocyte-macrophage-CSF mRNA can be detected after refeeding of cultures, although in quiescent cultures message for these factors is difficult to detect. Interleukin-3, IL-4, and IL-5 are not detectable by standard Northern blot analysis or bioassay of condition media. However, IL-3--detectable by reverse-transcriptase PCR and biologic activity--was confirmed by growth of factor-dependent cells on stromal cells with IL-3 antibody blocking of such growth. Stem cells resident on such stromal cells are mirrored by the high proliferative potential colony-forming cell assay and are responsive to a relatively large number of cytokines, with Steel factor being of central importance, appearing to be a critical component of various synergistic combinations. Steel factor allows reduced levels of other factors in such combinations and works early in a temporal sequence. Hematopoietic stem cells can engraft in normal nonmyeloablated hosts. Using a male/female BALB/c transplantation model, we have shown high rates of engraftment into normal animals, out after marrow infusion to 25 months, after marrow infusion and that post-5-fluorouracil bone marrow is quite deficient in such engraftment.(ABSTRACT TRUNCATED AT 250 WORDS)
