Osteogenesis of Heterotopically Transplanted Mesenchymal Stromal Cells in Rat Models of Chronic Kidney Disease

Authors

  • Rafael Kramann,

    Corresponding author
    1. Division of Nephrology and Clinical Immunology, Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
    2. Institute of Pathology, Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
    • Address correspondence to: Rafael Kramann, MD, Department of Nephrology and Clinical Immunology, Medical Faculty RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany. E-mail: rkramann@gmx.net

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  • Uta Kunter,

    1. Division of Nephrology and Clinical Immunology, Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
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  • Vincent M Brandenburg,

    1. Division of Cardiology, Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
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  • Isabelle Leisten,

    1. Institute of Pathology, Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
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  • Josef Ehling,

    1. Institute of Pathology, Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
    2. Department of Experimental Molecular Imaging (ExMI), Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
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  • Barbara M Klinkhammer,

    1. Division of Nephrology and Clinical Immunology, Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
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  • Ruth Knüchel,

    1. Institute of Pathology, Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
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  • Jürgen Floege,

    1. Division of Nephrology and Clinical Immunology, Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
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  • Rebekka K Schneider

    1. Institute of Pathology, Medical Faculty Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
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ABSTRACT

The current study is based on the hypothesis of mesenchymal stromal cells (MSCs) contributing to soft-tissue calcification and ectopic osteogenesis in chronic kidney disease (CKD). Rat MSCs were transplanted intraperitoneally in an established three-dimensional collagen-based model in healthy control animals and two rat models of CKD and vascular calcification: (1) 5/6 nephrectomy + high phosphorus diet; and (2) adenine nephropathy. As internal controls, collagen gels without MSCs were transplanted in the same animals. After 4 and 8 weeks, MSCs were still detectable and proliferating in the collagen gels (fluorescence-activated cell sorting [FACS] analysis and confocal microscopy after fluorescence labeling of the cells). Aortas and MSC-containing collagen gels in CKD animals showed distinct similarities in calcification (micro–computed tomography [µCT], energy-dispersive X-ray [EDX] analysis, calcium content), induction of osteogenic markers, (ie, bone morphogenic protein 2 [BMP-2], Runt related transcription factor 2 [Runx2], alkaline phosphatase [ALP]), upregulation of the osteocytic marker sclerostin and extracellular matrix remodeling with increased expression of osteopontin, collagen I/III/IV, fibronectin, and laminin. Calcification, osteogenesis, and matrix remodeling were never observed in healthy control animals and non-MSC–containing collagen gels in all groups. Paul Karl Horan 26 (PKH-26)-labeled, 3G5-positive MSCs expressed Runx2 and sclerostin in CKD animals whereas PKH-26-negative migrated cells did not express osteogenic markers. In conclusion, heterotopically implanted MSCs undergo osteogenic differentiation in rat models of CKD-induced vascular calcification, supporting our hypothesis of MSCs as possible players in heterotopic calcification processes of CKD patients. © 2013 American Society for Bone and Mineral Research.

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