Despite differential gene expression profiles pediatric MDS derived mesenchymal stromal cells display functionality in vitro.

Pediatric myelodysplastic syndrome (MDS) is a heterogeneous disease covering a spectrum ranging from aplasia (RCC) to myeloproliferation (RAEB(t)). In adult-type MDS there is increasing evidence for abnormal function of the bone-marrow microenvironment. Here, we extensively studied the mesenchymal stromal cells (MSCs) derived from children with MDS. MSCs were expanded from the bone-marrow of 17 MDS patients (RCC: n=10 and advanced MDS: n=7) and pediatric controls (n=10). No differences were observed with respect to phenotype, differentiation capacity, immunomodulatory capacity or hematopoietic support. mRNA expression analysis by Deep-SAGE revealed increased IL-6 expression in RCC- and RAEB(t)-MDS. RCC-MDS MSC expressed increased levels of DKK3, a protein associated with decreased apoptosis. RAEB(t)-MDS revealed increased CRLF1 and decreased DAPK1 expressions. This pattern has been associated with transformation in hematopoietic malignancies. Genes reported to be differentially expressed in adult MDS-MSC did not differ between MSC of pediatric MDS and controls. An altered mRNA expression profile, associated with cell survival and malignant transformation, of MSC derived from children with MDS strengthens the hypothesis that the micro-environment is of importance in this disease. Our data support the understanding that pediatric and adult MDS are two different diseases. Further evaluation of the pathways involved might reveal additional therapy targets.

Stem cell self-renewal: lessons from bone marrow, gut and iPS toward clinical applications.

The hematopoietic stem cell (HSC) is the prototype organ-regenerating stem cell (SC), and by far the most studied type of SC in the body. Currently, HSC-based therapy is the only routinely used SC therapy; however, advances in the field of embryonic SCs and induced pluripotent SCs may change this situation. Interest into in vitro generation of HSCs, including signals for HSC expansion and differentiation from these more primitive SCs, as well as advances in other organ-specific SCs, in particular the intestine, provide promising new applications for SC therapies. Here, we review the basic principles of different SC systems, and on the basis of the experience with HSC-based SC therapy, provide recommendations for clinical application of emerging SC technologies.

Toward a myeloablative regimen with clinical potential: II. Treosulfan induces specific skin graft tolerance across haploidentical MHC barriers.

Treosulfan is a water-soluble structural analog of busulfan, acting as a prodrug of alkylating epoxide species. It does not induce severe hepatotoxicity or veno-occlusive disease at or above the maximum tolerated dose, lacks significant nonhematological toxicity and has a limited organ toxicity. It is mainly indicated for the treatment of patients with ovarian cancer. In the present study, we report that permanent donor-specific tolerance and stable mixed multilineage chimerism can successfully be achieved across haploidentical MHC barriers when Treosulfan is administered in combination with anti-T-cell mAb and T-cell-depleted donor bone marrow cells. Furthermore, we show that less T-cell suppression is required when Treosulfan is included in the conditioning regimen. In conclusion, Treosulfan is a well-tolerated myeloablative agent with a low toxicity, and is a promising candidate drug for conditioning prior to bone marrow transplantation.

Towards a myeloablative regimen with clinical potential: I. Treosulfan conditioning and bone marrow transplantation allow induction of donor-specific tolerance for skin grafts across full MHC barriers.

To investigate whether we could create a radiation-free conditioning regimen to induce permanent mixed and multilineage chimerism and donor-specific tolerance, we treated recipient mice with anti-T-cell antibodies, varying and fractionated doses of Treosulfan and fully MHC disparate bone marrow cells. Treosulfan is mainly used in the treatment of ovarian cancer. It is a structural analog of busulfan, but it does not induce severe hepatotoxicity or veno-occlusive disease at or above the maximum tolerated dose, lacks significant nonhematological toxicity and has limited organ toxicity. We report here the successful induction of permanent mixed multilineage chimerism and donor-specific tolerance as was proven by skin transplantation and IFN-gamma ELISPOT. In conclusion, because of its lower nonhematological toxicity, compared with other myeloablative regimens (eg irradiation or busulfan admin- istration), Treosulfan could be a better candidate for conditioning to induce donor-specific allograft tolerance.

Fibroblast-like synoviocytes from rheumatoid arthritis patients have intrinsic properties of follicular dendritic cells.

The production of IgG rheumatoid factors in the inflamed synovium of many patients with rheumatoid arthritis (RA) implies that local sites exist where plasma cell precursors undergo isotype switching and affinity maturation by somatic mutation and selection. Lymphonodular infiltrates of the synovium-containing germinal centers (GCs), are candidates to fulfill such function in the rheumatoid patient. It has been suggested that these GCs are organized around, obviously ectopic, follicular dendritic cells (FDCs). The present study attempts to find out whether these putative FDCs 1) are specific for RA, 2) have the same phenotype and functional capacity as FDCs in lymphoid organs, and 3) may locally differentiate from fibroblast-like synoviocytes (FLS). Synovial biopsies from patients with RA versus non-RA, yet arthritic backgrounds, were compared. Cells with the FDC phenotype were found in both RA and non-RA tissues as well as in single cell suspensions thereof. When FLS were cultured in vitro, part of these cell lines could be induced with IL-1beta and TNF-alpha to express the FDC phenotype, irrespective of their RA or non-RA background. By contrast, the FDC function, i.e., stable binding of GC B cells and switching off the apoptotic machinery in B cells, appeared to be the prerogative of RA-derived FLS only. The present data indicate that FDC function of FLS in RA patients is intrinsic and support the idea that synovial fibroblast-like cells have undergone some differentiation process that is unique for this disease.