The CD34-like protein PODXL and α6-integrin (CD49f) identify early progenitor MSCs with increased clonogenicity and migration to infarcted heart in mice

Abstract

We screened for surface proteins expressed only by the early progenitor cells present in low-passage, low-density cultures of the adult stem/progenitor cells from bone marrow referred to as mesenchymal stem cells or multipotent stromal cells (MSCs). Six proteins were identified that were selectively expressed in the early progenitors: podocalyxin-like protein (PODXL), ␣6-integrin (CD49f), ␣4-integrin (CD49d), c-Met, CXCR4, and CX3CR1. All were previously shown to be involved in cell trafficking or tumor progression. Antibodies to CD49f and PODXL, a sialomucin in the CD34 family, were the most robust for FACScan assays. PODXL hi /CD49f hi MSCs were more clonogenic and differentiated more efficiently than PODXL lo /CD49f lo cells. Inhibition of expression of PODXL with RNA interference caused aggregation of the cells. Furthermore, PODXL hi /CD49f hi MSCs were less prone to produce lethal pulmonary emboli, and larger numbers were recovered in heart and kidney after intravenous infusion into mice with myocardial infarcts. (Blood. 2009;113:816-826) IntroductionAmong the cells being used for cell therapies for nonhematopoietic tissues are the stem/progenitor cells from bone marrow that were referred to initially as fibroblast colony-forming units, 1 subsequently as marrow stromal cells, then as mesenchymal stem cells 2 and, most recently, as multipotent mesenchymal stromal cells or MSCs. 3 Clinical trials with MSCs are now in progress, 4-9 but several questions are still unresolved as to how the cells should be isolated, expanded in culture, and characterized. One view is that confluent cultures of MSCs ( Figure 1A) are useful and perhaps the optimal preparations for therapy. An opposing view is that confluent cultures of MSCs are partially committed to differentiation or even senescence. Therefore, they lack some of the therapeutic potentials of low-density cultures that contain a subpopulation of rapidly self-replicating cells [10][11][12][13] that display a different pattern of expressed genes, 14 that have a greater capacity to generate singlecell-derived clones, 10,11 and that more efficiently engraft in vivo. 15 MSCs were originally described by Friedenstein et al 1 and Owen and Friedenstein,16 who isolated the cells by their ready adherence to tissue culture surfaces, an isolation technique that subsequently was followed by most investigators. 17 The cells were characterized primarily by their ability to generate colonies in culture and to differentiate into adipocytes, osteoblasts, and chondrocytes. Numerous attempts were made to develop more specific procedures for isolation and characterization of the cells by preparing antibodies to surface epitopes on MSC. The first antibody was the monoclonal immunoglobulin M antibody STRO-1, which was raised against confluent cultures of human MSCs that were used as feeder layers for hematopoietic stem cells. 18 STRO-1 alone or in combination with other antibodies subsequently was used extensively to identify and isolate MSCs. [19][20][21][22][23][24][25][26] Also, a se...

Aggregation of human mesenchymal stromal cells (MSCs) into 3D spheroids enhances their antiinflammatory properties

“…Quantitative assays confirmed some of the important differences. As expected, there was a marked decrease in the anticell-adhesion protein PODXL (24) and a decrease in cell cycling. Of special note was that several of the differences had important implications for the potential therapeutic uses of hMSCs.…”

“…Therefore a significantly smaller number was trapped in the lung after i.v. infusion and thus larger numbers were found in many tissues (14,24).…”

“…Because aggregated hMSCs were detected in the pulmonary microemboli observed after i.v. infusion of the cells (14,24), we tested the hypothesis that aggregation of hMSCs in culture may provide an effective procedure to preactivate the cells to express TSG-6, and thereby, enhance their antiinflammatory effects through a reduction in the lag period for expression of the gene in vivo.…”

MSCs derived from iPSCs with a modified protocol are tumor-tropic but have much less potential to promote tumors than bone marrow MSCs

“…MSCs from various tissues have a unique tumor-homing capacity that enables them to serve as vehicles for gene therapy of advanced cancers. The tumor tropism of these MSCs is mediated by multiple chemokine receptors such as CXCR4 and CXCR6 (4-6), CD44 (33), and VEGFR1 (3) and integrins such as ITGA6 and ITGB1 (34,35). The expression of VEGFR1 was dramatically higher in iPSC-MSCs than in BM-MSCs, whereas the expression of other homing-related genes was comparable between iPSC-MSCs and BM-MSCs ( Fig.…”

Allogeneic Murine Mesenchymal Stem Cells: Migration to Inflamed Joints In Vivo and Amelioration of Collagen Induced Arthritis When Transduced to Express CTLA4Ig

“…We identified eGFP DNA in the lungs and liver after systemic infusion of FVB-GFP MSCs to mice with and without arthritis. MSCs have been shown to engraft to lung and liver and this is to be expected due to the high circulating blood volume in these organs [48][49][50]. During active inflammation, hepatocytes become upregulated and increase production of acute phase proteins [51] leading to the hypothesis that the increased hepatocyte activity may generate chemoattractants for MSCs.…”