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Updated: Feb 20, 2026
Isolation, Culture, and Differentiation of Bone Marrow Stromal Cells and Osteoclast Progenitors from Mice
Published on: January 6, 2018
Immortalization and characterization of osteoblast cell lines generated from wild-type and Nmp4-null mouse bone
Marta B Alvarez1, Paul Childress, Binu K Philip
1Department of Anatomy & Cell Biology, Indiana University School of Medicine (IUSM), Indianapolis, IN 46202, USA.
Abstract:
Intermittent parathyroid hormone (PTH) adds new bone to the osteoporotic skeleton; the transcription factor Nmp4/CIZ represses PTH-induced bone formation in mice and as a consequence is a potential drug target for improving hormone clinical efficacy. To explore the impact of Nmp4/CIZ on osteoblast phenotype, we immortalized bone marrow stromal cells from wildtype (WT) and Nmp4-knockout (KO) mice using murine telomerase reverse transcriptase. Clonal lines were initially chosen based on their positive staining for alkaline phosphatase and capacity for mineralization. Disabling Nmp4/CIZ had no gross impact on osteoblast phenotype development. WT and KO clones exhibited identical sustained growth, reduced population doubling times, extended maintenance of the mature osteoblast phenotype, and competency for differentiating toward the osteoblast and adipocyte lineages. Additional screening of the immortalized cells for PTH-responsiveness permitted further studies with single WT and KO clones. We recently demonstrated that PTH-induced c-fos femoral mRNA expression is enhanced in Nmp4-KO mice and in the present study we observed that hormone stimulated either an equivalent or modestly enhanced increase in c-fos mRNA expression in both primary null and KO clone cells depending on PTH concentration. The null primary osteoblasts and KO clone cells exhibited a transiently enhanced response to bone morphogenetic protein 2 (BMP2). The clones exhibited lower and higher expressions of the PTH receptor (Pthr1) and the BMP2 receptor (Bmpr1a, Alk3), respectively, as compared to primary cells. These immortalized cell lines will provide a valuable tool for disentangling the complex functional roles underlying Nmp4/CIZ regulation of bone anabolism.
Insights
The transcription factor Nmp4/CIZ represses parathyroid hormone (PTH)-induced bone formation. Disabling Nmp4/CIZ in osteoblasts did not alter their development but enhanced PTH and bone morphogenetic protein 2 (BMP2) responses.
Area of Science:
- Bone biology and endocrinology
- Osteoblast differentiation and function
- Molecular regulation of bone metabolism
Background:
- Intermittent parathyroid hormone (PTH) therapy stimulates bone formation, crucial for treating osteoporosis.
- The transcription factor Nmp4/CIZ is known to inhibit PTH-induced bone anabolism in mice.
- Nmp4/CIZ represents a potential therapeutic target to enhance the efficacy of PTH treatment.
Purpose of the Study:
- To investigate the role of Nmp4/CIZ in regulating osteoblast phenotype and function.
- To develop and utilize immortalized Nmp4-knockout (KO) osteoblast cell lines for studying Nmp4/CIZ's effects.
- To assess the impact of Nmp4/CIZ deficiency on PTH and bone morphogenetic protein 2 (BMP2) responsiveness.
Main Methods:
- Immortalization of wildtype (WT) and Nmp4-knockout (KO) mouse bone marrow stromal cells using murine telomerase reverse transcriptase.
- Selection of clonal cell lines based on alkaline phosphatase staining and mineralization capacity.
- Assessment of osteoblast phenotype, proliferation, differentiation potential, and responsiveness to PTH and BMP2.
Main Results:
- Nmp4/CIZ deficiency did not grossly affect osteoblast phenotype development, including sustained growth and differentiation capacity.
- PTH-induced c-fos mRNA expression was equivalent or modestly enhanced in Nmp4-KO cells compared to WT.
- Nmp4-null primary osteoblasts and Nmp4-KO clone cells showed a transiently enhanced response to BMP2.
Conclusions:
- Immortalized Nmp4-KO osteoblast cell lines are valuable tools for studying Nmp4/CIZ's role in bone metabolism.
- Nmp4/CIZ does not appear essential for basic osteoblast development but influences hormonal responses.
- Further research using these cell lines can elucidate Nmp4/CIZ's complex regulatory functions in bone anabolism.
