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

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 þ 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 [mCT], 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.

Romosozumab or Alendronate for Fracture Prevention in Women with Osteoporosis

“…Sclerostin is constitutively expressed in the aorta [16][17][18] and up-regulated in foci of vascular and valvular calcification. [19][20][21][22] The function of sclerostin in the vasculature is unknown. Although sclerostin may function as a negative regulator of vascular calcification and sclerostin inhibition could promote vascular calcification, studies have shown conflicting results.…”

Resistance to neoplastic transformation ofex-vivoexpanded human mesenchymal stromal cells after exposure to supramaximal physical and chemical stress

“…For the sake of patient safety, any clinical application of MSCs should take into account potential risks, such as ectopic tissue formation [14, 15] and tumor generation caused by malignant transformation of the cells during ex-vivo expansion [16]. After initial reports on the occurrence of neoplastic transformation in ex-vivo expanded huMSCs after long-term culture [16, 17, 18] this event has been subsequently described as uncommon, with an estimated frequency of <10 −9 [19, 20, 21, 22].…”

Association of circulating sclerostin with vascular calcification in Afro-Caribbean men

“…Although sclerostin is an established regulator of bone mineralization (17), its potential role in vascular biology and arterial health is less clear. Sclerostin has been detected in the human aorta(18) and is up-regulated in calcifying vascular smooth muscle cells(19, 20) and calcified valvular plaques(21). The relationship of human serum sclerostin and vascular calcification, to our knowledge, has been investigated in four previous studies with two showing a direct correlation with calcification(22, 23) and two reporting an inverse correlation(24, 25).…”