A combined strategy using bioluminescence imaging, bone densitometry and histology was used to analyze the bone regeneration capacity of human bone marrow (hBMSC) and adipose tissue (hAMSC) mesenchymal stem cells, seeded in an osteoconductive arginine-glycine-aspartate (RGD) crosslinked hydrogel scaffold, implanted in a mouse calvarial bone defect. We show that firefly luciferase labeled stem cells can be monitored in vivo through a prolonged 90 days period, during which hBMSCs survive better than hAMSCs and that the density of scaffold bearing defects increased significantly more than that of defects without scaffolds.
"Toma et al.  evaluated the fate of MSCs after their vascular delivery into rat cremaster muscle microcirculation and found that after injection, microvascular plugging with obstruction of flow lead to a microischemia, resulting in loss of 86% of the cells within the first 24 hours. Degano et al.  analyzed the bone regenerating capacity of human bone marrow (hBMSC) and adipose tissue (hAMSC) MSCs implanted in a mouse calvarial bone defect and found that at 90 days, 37% of hBMSCs remained alive compared with only 5% of hAMSCs. A likely explanation for this limited cellular survival is that on implantation, MSCs encounter an ischemic environment composed of low oxygen tension and nutrient deprivation . "
[Show abstract][Hide abstract] ABSTRACT: Advances in the field of stem cell technology have stimulated the development and increased use of allogenic bone grafts containing live mesenchymal stem cells (MSCs), also known as cellular bone matrices (CBMs). It is estimated that CBMs comprise greater than 17% of all bone grafts and bone graft substitutes used.
The spine journal: official journal of the North American Spine Society 06/2014; 14(11). DOI:10.1016/j.spinee.2014.05.024 · 2.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this work we have evaluated the capacity of BMP-2 and fibrin-binding PDGF-BB to support cell growth and induce bone regeneration using two different imaging technologies to improve understanding of structural and organizational processes participating in tissue repair. Human mesenchymal stem cells from adipose tissue (hAMSCs) expressing two luciferase genes, one under the control of the CMV promoter and the other under the control of a tissue-specific promoter (osteocalcin or PECAM), were seeded in fibrin matrices containing BMP-2 and fibrin-binding PDGF-BB, and further implanted intramuscularly or in a mouse calvarial defect. Then, cell growth and bone regeneration were monitored by bioluminescence imaging (BLI) to analyze the evolution of target gene expression, indicative of cell differentiation towards the osteoblastic and endothelial lineages. Non-invasive imaging was supplemented with micro-computed tomography (microCT) to evaluate bone regeneration and high-resolution microCT of vascular casts. Results from BLI showed hAMSC growth during the first week in all cases, followed by a rapid decrease in cell number; as well as an increment of osteocalcin but not PECAM-1 expression 3 weeks after implantation. Results from microCT show that the delivery of BMP-2 and PDGF-BB by fibrin induced the formation of more bone and improves vascularization, resulting in more abundant and thicker vessels, in comparison with controls. Although inclusion of hAMSCs in the fibrin matrices made no significant difference in any of these parameters, there was a significative increment in the connectivity of the vascular network in defects treated with hAMSCs.
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