Network-driven discovery yields new insight into Shox2-dependent cardiac rhythm control.

The homeodomain transcription factor SHOX2 is involved in the development and function of the heart's primary pacemaker, the sinoatrial node (SAN), and has been associated with cardiac conduction-related diseases such as atrial fibrillation and sinus node dysfunction. To shed light on Shox2-dependent genetic processes involved in these diseases, we established a murine embryonic stem cell (ESC) cardiac differentiation model to investigate Shox2 pathways in SAN-like cardiomyocytes. Differential RNA-seq-based expression profiling of Shox2+/+ and Shox2-/- ESCs revealed 94 dysregulated transcripts in Shox2-/- ESC-derived SAN-like cells. Of these, 15 putative Shox2 target genes were selected for further validation based on comparative expression analysis with SAN- and right atria-enriched genes. Network-based analyses, integrating data from the Mouse Organogenesis Cell Atlas and the Ingenuity pathways, as well as validation in mouse and zebrafish models confirmed a regulatory role for the novel identified Shox2 target genes including Cav1, Fkbp10, Igfbp5, Mcf2l and Nr2f2. Our results indicate that genetic networks involving SHOX2 may contribute to conduction traits through the regulation of these genes.

A novel approach to genetic engineering of T-cell subsets by hematopoietic stem cell infection with a bicistronic lentivirus.

Lentiviral modification of hematopoietic stem cells (HSCs) paved the way for in vivo experimentation and therapeutic approaches in patients with genetic disease. A disadvantage of this method is the use of a ubiquitous promoter leads not only to genetic modification of the leukocyte subset of interest e.g. T-cells, but also all other subsequent leukocyte progeny of the parent HSCs. To overcome this limitation we tested a bicistronic lentivirus, enabling subset specific modifications. Designed novel lentiviral constructs harbor a global promoter (mPGK) regulating mCherry for HSCs selection and a T-cell specific promoter upstream of eGFP. Two T-cell specific promoters were assessed: the distal Lck-(dLck) and the CD3δ-promoter. Transduced HSCs were FACS sorted by mCherry expression and transferred into sublethally irradiated C57/BL6 mice. Successful transplantation and T-cell specific expression of eGFP was monitored by peripheral blood assessment. Furthermore, recruitment response of lentiviral engineered leukocytes to the site of inflammation was tested in a peritonitis model without functional impairment. Our constructed lentivirus enables fast generation of subset specific leukocyte transgenesis as shown in T-cells in vivo and opens new opportunities to modify other HSCs derived subsets in the future.

Isolation of human mesenchymal stromal cells is more efficient by red blood cell lysis.

BACKGROUND: Human mesenchymal stromal cells (MSC) have raised high hopes for tissue engineering and clinical therapy. Their isolation usually involves density fractionation of mononuclear cells (MNC) but this is difficult to standardize, especially under good manufacturing practice (GMP) conditions. MSC represent a heterogeneous mixture of cell types and the composition of subpopulations is affected by the initial steps of cell preparation. METHODS: This study describes a straightforward method for isolation of human MSC based on red blood cell (RBC) lysis with ammonium chloride. Colony formation was compared directly with Ficoll density fractionation and culture of an untreated whole bone marrow (BM) aspirate. RESULTS: After 7 days the number of fibroblastic colony-forming units (CFU-F) per milliliter of BM aspirate was slightly higher upon RBC lysis and the colonies were significantly larger compared with density fractionation, possibly because of maintenance of platelets. In contrast, colony formation was much lower in untreated BM. The heterogeneous composition of subpopulations was reflected by differences between the initial colonies with regard to growth pattern (tight or disperse) and cell morphology (round or elongated). This heterogeneous composition was not affected by the three different isolation methods. Furthermore, enrichment of CD271(+) cells resulted in the same morphologic heterogeneity. All cell preparations demonstrated the same immunophenotype using a panel of surface markers and displayed adipogenic and osteogenic differentiation potential. DISCUSSION: This study demonstrates that human MSC can be efficiently isolated by RBC lysis. This technique is faster and can be standardized more easily for clinical application of MSC.

G-CSF-mobilized peripheral blood progenitor cells for allogeneic transplantation: comparison of T cell depletion strategies using different CD34+ selection systems or CAMPATH-1.

Allogeneic transplantation of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood progenitor cells (PBPC) appears to be an attractive alternative to allogeneic bone marrow transplantation (BMT). However, because vast amounts of potentially graft-vs.-host-reactive T cells are transfused with PBPC grafts, the use of PBPC in the allogeneic setting may be associated with an increased incidence or severity of graft-vs.-host disease (GVHD). To evaluate strategies for prevention of GVHD after PBPC allografting, we have studied T cell depletion (TCD) of G-CSF-mobilized PBPC samples harvested from six healthy donors and from five patients scheduled for autologous PBPC transplantation. Three approaches (CAMPATH-1 plus autologous complement [C], immunomagnetic CD34+ cell selection, and biotin-avidin-mediated CD34+ cell selection) were compared. TCD of PBPC samples with the monoclonal antibody (MAb) CAMPATH-1 plus autologous C resulted in a median elimination of 2.16 log CD3+ T cells, whereas 39% of CD56+ natural killer (NK) cells and 56% of CD34+ progenitor cells were recovered. TCD by CD34+ cell selection with the Isolex (Baxter, Munich, Germany) or Ceprate (CellPro, Bothell, WA) devices achieved median depletions (Isolex vs. Ceprate) of 4.04 vs. 3.12 log T cells and > 5 vs. 3.27 log NK cells while allowing the recovery of 36 vs. 27% CD34+ cells. The median purity of CD34+ cells in the final product was 1.7 (CAMPATH-1), 94 (Isolex), and 65% (Ceprate). We conclude that all methods tested effectively deplete T cells from PBPC preparations harvested from healthy donors. Whereas immunomagnetic CD34+ selection is most effective in terms of elimination of T cells, the less intensive T and NK cell depletions achieved with CAMPATH-1 might be advantageous with regard to retaining engraftment potential and graft-vs.-leukemia (GVL) activity of PBPC allografts.

Freezing of cells--replacement of serum by oxypolygelatine.

A commercially available plasma expander (Gelifundol) containing 5.5% oxypolygelatine in buffered saline was used instead of serum as a supplement for freezing several types of human cell and a mouse myeloma cell line in liquid nitrogen. Viability, recovery, proliferation and cytotoxic activity were compared after freezing with a plasma expander and after conventional freezing with human AB serum or fetal calf serum. The plasma expander proved to be equivalent or superior to AB serum by all parameters tested and acceptable even when compared with fetal calf serum. Furthermore, this preparation is cheap, sterile, free of BSE, viral and mycoplasmal contamination or antibodies and foreign serum proteins. We therefore recommend it for freezing of cells for culture of HLA typing.

Analysis of tolerance inducing mechanism after application of oncogen-transformed macrophages.

The purpose of this study was to examine the expression of T cell receptors (TCR) and their V beta subclasses under the influence of the parental cell line P388D1 and its clones mos2 and mos3, using a mouse model. It was shown, that v-mos oncogene-transformed cells of this line (mos2) induced selective immunological unresponsiveness in vitro. Because the induction of tolerance is of a central importance for the organ transplantation, this phenomenon, found in vitro, was also studied in vivo. We found that the in vivo injection of mos2 cells into mice induced a state of selective noncreativity. To further analyse these effects, we studied whether specific tolerance is the consequence of a decreased number of essential receptors or receptor families. For this purpose C57BL/6 mice were immunized with cells of the parental line P388D1 or mos2 and mos3 clones. Their spleen and thymus cells were examined phenotypically. The most impressive result of this study was a clearly changed amount of T cells receptors in mos2 immunized mice, in which a state of tolerance was induced. In these mice only the expression of CD3 T receptors as well as that of the V beta 11 chains was reduced. In spleen of these mice the CD3 expression was decreased, compared to D1 or nonimmunized control animals by 54-58% and compared to mos3 mice by 38-40%. Even though the differences in the thymus were not very pronounced, we still saw a decrease in CD3 stained cells selective in mos2 immunized C57B1/6. The expression of V beta 11 chains on the surface of spleen cells of mos2 animals was reduced by 33.3%, on the thymocytes even by 50% comparing to that in nonimmunized mice. Whether the reduced expression of T receptor V beta families is due to changes in the genetic material (cDNA), has to be studied.

Tissue distribution and persistence in mice of plasmid DNA encapsulated in a PLGA-based microsphere delivery vehicle.

Information regarding the distribution and persistence of DNA encapsulated in poly-(lactide co-glycolide) microspheres was collected to provide additional information regarding the safety of DNA vaccines and to support the clinical testing of this new delivery system for DNA. Plasmid DNA was encapsulated in poly(lactide co-glycolide) microspheres and the distribution and persistence of plasmid in murine tissues resulting from parenteral administration were examined by a sensitive PCR assay. Encapsulated DNA delivered by intramuscular or subcutaneous injection can be detected for 100 days post-injection and is distributed primarily at the site of injection and the lymphoid organs. Intravenous administration results in more widespread dissemination with long term persistence limited to the lymphoid organs and those of the reticuloendothelial system. Specific cellular uptake of DNA by professional antigen presenting cells (APCs) following injection suggests the utility of microspheres as DNA delivery agents. Distribution and persistence studies support the safety of encapsulated DNA and the specific cellular uptake of DNA by professional APCs following injection suggests the utility of microspheres as DNA delivery agents.