Chronic kidney failure mineral bone disorder leads to a permanent loss of hematopoietic stem cells through dysfunction of the stem cell niche

In chronic kidney disease (CKD), endothelial injury, is associated with disease progression and an increased risk for cardiovascular complications. Circulating cells with vascular reparative functions are hematopoietic and also reduced in CKD. To explore the mechanistic basis behind these observations, we have investigated hematopoietic stem cell (HSC) homeostasis in a mouse model for non-progressive CKD-mineral and bone disorder with experimentally induced chronic renal failure (CRF). In mice subjected to 12 weeks of CRF, bone marrow HSC frequencies were decreased and transplantation of bone marrow cells from CRF donors showed a decrease in long-term HSC repopulation compared to controls. This loss was directly associated with a CRF-induced defect in the HSC niche affecting the cell cycle status of HSC and could not be restored by the PTH-reducing agent cinacalcet. In CRF, frequencies of quiescent (G0) HSC were decreased coinciding with an increase in hematopoietic progenitor cells (HPC) in the S-and G2-phases of cell cycle. Moreover, in CRF mice, HSC-niche supporting macrophages were decreased compared to controls concomitant to impaired B lymphopoiesis. Our data point to a permanent loss of HSC and may provide insight into the root cause of the loss of homeostatic potential in CKD

Preparing for cell culture scale-out: establishing parity of bioreactor- and flask-expanded mesenchymal stromal cell cultures

Background: Cell-based therapies have the potential to become treatment options for many diseases, but efficient scale-out of these therapies has proven to be a major hurdle. Bioreactors can be used to overcome this hurdle, but changing the culture method can introduce unwanted changes to the cell product. Therefore, it is important to establish parity between products generated using traditional methods versus those generated using a bioreactor.Methods: Mesenchymal stromal cells (MSCs) are cultured in parallel using either traditional culture flasks, spinner vessels or a new bioreactor system. To investigate parity between the cells obtained from different methods, harvested cells are compared in terms of yield, phenotype and functionality.Results: Bioreactor-based expansion yielded high cell numbers (222–510 million cells). Highest cell expansion was observed upon culture in flasks [average 5.0 population doublings (PDL)], followed by bioreactor (4.0 PDL) and spinner flasks (3.3 PDL). Flow cytometry confirmed MSC identity (CD73+, CD90+ and CD105+) and lack of contaminating hematopoietic cell populations. Cultured MSCs did not display genetic aberrations and no difference in differentiation and immunomodulatory capacity was observed between culture conditions. The response to IFNγ stimulation was similar for cells obtained from all culture conditions, as was the capacity to inhibit T cell proliferation.Conclusions: The new bioreactor technology can be used to culture large amounts of cells with characteristics equivalent to those cultured using traditional, flask based, methods

Poor Outcomes for IgD Multiple Myeloma Patients Following High-Dose Melphalan and Autologous Stem Cell Transplantation: A Single Center Experience

Immunoglobulin (Ig) D multiple myeloma (MM) accounts for 2% of all MM cases and has been reported to be associated with poor prognosis compared with other MM subtypes. The aim of the present study was to compare the effects of high-dose melphalan treatment and autologous stem cell transplantation (ASCT) on the survival of patients with IgD MM and patients with other MM subtypes. Between November 1998 and January 2005, a total of 77 patients with MM who underwent ASCT at the Asan Medical Center were enrolled in this study. High-dose melphalan (total 200 mg/m2) was used as high-dose chemotherapy. The study population was divided into two groups based on MM subtype: those with IgD MM; and those with other MM subtypes. A total of 8 patients with IgD MM were identified, accounting for about 10% of the study population. Thirty-six patients (47%) had IgG MM, 17 patients (22%) had IgA MM, and 16 patients (20%) had free light-chain MM. The two groups were similar in baseline characteristics. The median follow-up was 17 months and the median overall survival (OS) was 39 months. In the IgD MM group, median event-free survival (EFS) and OS were 6.9 and 12 months, respectively. In the patients with other MM subtypes, median EFS and OS were 11.5 and 55.5 months (p=0.01, p<0.01), respectively. Multivariate analysis of all patients identified IgD subtype (p=0.002) and Southwest Oncology Group (SWOG) stage 2 or greater at the time of ASCT (p=0.01) as adverse prognostic factors for survival. In this small study at a single center in Korea, patients with IgD MM had poorer outcomes after ASCT than did patients with other MM subtypes

Biological Properties of Cells Other Than HSCs

The array of cellular players involved in the biology of HSCT clearly extends beyond HSC themselves and, in the case of transplantation from allogeneic sources, importantly includes cells of the innate and adaptive immune system. Historically, the discovery of the HLA system and the functional characterization of the different immune cell types had a transformational impact on our current understanding of the pathobiological sequelae of allo-HSCT (rejection, GVHD, the GVL effect). This body of knowledge coupled to the most recent exploit of biotechnology nowadays allows us to design strategies for in vivo stimulation or adoptive transfer of specific immune cell types with the potential to dramatically improve transplantation outcome

Targeting Lysophosphatidic Acid Signaling Retards Culture-Associated Senescence of Human Marrow Stromal Cells

Marrow stromal cells (MSCs) isolated from mesenchymal tissues can propagate in vitro to some extent and differentiate into various tissue lineages to be used for cell-based therapies. Cellular senescence, which occurs readily in continual MSC culture, leads to loss of these characteristic properties, representing one of the major limitations to achieving the potential of MSCs. In this study, we investigated the effect of lysophosphatidic acid (LPA), a ubiquitous metabolite in membrane phospholipid synthesis, on the senescence program of human MSCs. We show that MSCs preferentially express the LPA receptor subtype 1, and an abrogation of the receptor engagement with the antagonistic compound Ki16425 attenuates senescence induction in continually propagated human MSCs. This anti-aging effect of Ki16425 results in extended rounds of cellular proliferation, increased clonogenic potential, and retained plasticity for osteogenic and adipogenic differentiation. Expressions of p16Ink4a, Rb, p53, and p21Cip1, which have been associated with cellular senescence, were all reduced in human MSCs by the pharmacological inhibition of LPA signaling. Disruption of this signaling pathway was accompanied by morphological changes such as cell thinning and elongation as well as actin filament deformation through decreased phosphorylation of focal adhesion kinase. Prevention of LPA receptor engagement also promoted ubiquitination-mediated c-Myc elimination in MSCs, and consequently the entry into a quiescent state, G0 phase, of the cell cycle. Collectively, these results highlight the potential of pharmacological intervention against LPA signaling for blunting senescence-associated loss of function characteristic of human MSCs