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Adipocyte differentiation defect in mesenchymal stromal cells of patients with malignant infantile osteopetrosis
1Department of Pediatrics, Division of Hematology-Bone Marrow Transplantation Unit, University of Hacettepe Medical School, Ankara, Turkey. duckan@hacettepe.edu.tr
Insights
Malignant infantile osteopetrosis (MIOP) involves defective osteoclasts. In this study, mesenchymal stromal cells (MSCs) from MIOP patients showed impaired adipogenic differentiation, suggesting a bone marrow microenvironment defect contributing to the disease.
Area of Science:
- Bone Biology
- Hematology
- Cell Biology
Background:
- Malignant infantile osteopetrosis (MIOP) is a rare genetic disorder characterized by defective osteoclast function, leading to impaired bone resorption and often fatal outcomes in infancy.
- Mesenchymal stromal cells (MSCs) are crucial components of the bone marrow microenvironment, interacting closely with hematopoietic cells, including osteoclasts.
- This study investigates a potential link between MSC defects and osteoclast dysfunction in the context of MIOP.
Purpose of the Study:
- To investigate the characteristics and differentiation potential of bone marrow mesenchymal stromal cells (MSCs) derived from patients with malignant infantile osteopetrosis (MIOP).
- To determine if defects in MSCs contribute to the osteopetrosis phenotype observed in MIOP patients.
Main Methods:
- Bone marrow MSCs were isolated from six MIOP patients and expanded in vitro.
- Characterization included assessment of morphology, plastic adherence, immunophenotype, and multilineage differentiation potential.
- Adipogenic differentiation was specifically analyzed using gene expression of key adipogenic markers and Oil Red O staining.
Main Results:
- Patient-derived MSCs exhibited normal physical and immunophenotypic characteristics compared to healthy controls.
- A significant in vitro defect in adipogenic differentiation was observed in MIOP MSCs.
- This defect was associated with reduced or absent expression of critical adipogenic transcripts (e.g., PPARG, LEP, ADPN) upon induction.
- Bone marrow transplantation showed only minimal improvement in MSC adipogenic potential.
Conclusions:
- MIOP is associated with an in vitro failure of MSCs to differentiate into adipocytes, indicating a potential bone marrow microenvironment defect.
- This MSC defect may contribute to osteoclast dysfunction or be a consequence of the osteopetrotic bone marrow environment.
- Further research is warranted to elucidate the pathophysiological significance of this MSC defect and its potential therapeutic implications for MIOP.
Background:
Malignant infantile osteopetrosis (MIOP) is a disorder of osteoclasts characterized by defective bone resorption and death in infancy. The multipotent mesenchymal stromal cells (MSC) and their progeny (osteoblasts) are major components of the bone marrow (BM) microenvironment and are found in close contact with cells of hematopoietic origin, including osteoclasts. We hypothesized that MSC defects may be associated with osteoclast dysfunction and osteopetrosis phenotype.
Methods:
BM MSC, obtained from six patients with MIOP, were expanded in vitro and characterized by morphology, plastic-adherence, immunophenotype and multilineage differentiation potential.
Results:
Physical and immunophenotypic characteristics of patient MSC were similar to healthy age-matched controls. However, an isolated in vitro differentiation defect toward adipogenic lineage was demonstrated in patient MSC and confirmed by low or absent expression of adipogenic transcripts (peroxisome proliferator-activated receptor-gamma, adipophilin, stearoyl-CoA desaturase, leptin and adiponectin) upon induction of adipogenesis. Following BM transplantation, minimal improvement in adipogenic potency of MSC was demonstrated by Oil Red O staining.
Discussion:
MIOP is associated in vitro with a failure of MSC to differentiate into an adipogenic lineage, suggesting a BM microenvironment defect. The defect may contribute to osteoclast dysfunction, or may be attributed to the effect of the osteopetrotic marrow environment. Further investigations should determine the pathophysiologic importance of this novel defect, and could perhaps contribute to consideration of MSC therapy in MIOP.
