Microbial composition of Saharan dust plumes deposited as red rain in Granada (Southern Spain).

During durst storms, also biological material is transported from arid areas such as the Sahara Desert. In the present work, rain samples containing significant amounts of mineral dust have been collected in Granada during different red rain episodes. Biological features (bacteria, biofilm, pollen grain and fungal spore) as well as size-particle distribution and mineralogical composition were studied by SEM. Nanobacteria were observed for the first time in red rain samples. A preliminary metabarcoding analysis was performed on three red rain samples. Here, Bacillota made up 18 % and Pseudomonadota 23 % of the whole prokaryotic community. The fungal community was characterized by a high abundance of Ascomycota and, dependent on the origin, the presence of Chytridiomycota. By means of 16S rRNA sequencing, 18 cultivable microorganisms were identified. In general, members of the phyla Pseudomonadota and Bacillota made up the majority of taxa. Some species, such as Peribacillus frigoritolerans and Bacillus halotolerans were isolated during three different red rain episodes. Generally, red rain carries a wide variety of microorganisms, being their ecosystem and health effects largely unknown.

Generation of mesenchymal stromal cells from urine-derived iPSCs of pediatric brain tumor patients.

Human induced pluripotent stem cells (iPSCs) provide a virtually inexhaustible source of starting material for next generation cell therapies, offering new opportunities for regenerative medicine. Among different cell sources for the generation of iPSCs, urine cells are clinically relevant since these cells can be repeatedly obtained by non-invasive methods from patients of any age and health condition. These attributes encourage patients to participate in preclinical and clinical research. In particular, the use of urine-derived iPSC products is a convenient strategy for children with brain tumors, which are medically fragile patients. Here, we investigate the feasibility of using urine samples as a source of somatic cells to generate iPSC lines from pediatric patients with brain tumors (BT-iPSC). Urinary epithelial cells were isolated and reprogrammed using non-integrative Sendai virus vectors harboring the Yamanaka factors KLF4, OCT3/4, SOX2 and C-MYC. After reprogramming, BT-iPSC lines were subject to quality assessment and were compared to iPSCs obtained from urine samples of non-tumor pediatric patients (nonT-iPSC). We demonstrated that iPSCs can be successfully derived from a small volume of urine obtained from pediatric patients. Importantly, we showed that BT-iPSCs are equivalent to nonT-iPSCs in terms of morphology, pluripotency, and differentiation capacity into the three germ layers. In addition, both BT-iPSCs and nonT-iPSCs efficiently differentiated into functional mesenchymal stem/stromal cells (iMSC) with immunomodulatory properties. Therefore, this study provides an attractive approach to non-invasively generate personalized iMSC products intended for the treatment of children with brain tumors.

Mesenchymal stromal cell treatment of donor kidneys during ex vivo normothermic machine perfusion: A porcine renal autotransplantation study.

Normothermic machine perfusion (NMP) of injured kidneys offers the opportunity for interventions to metabolically active organs prior to transplantation. Mesenchymal stromal cells (MSCs) can exert regenerative and anti-inflammatory effects in ischemia-reperfusion injury. The aims of this study were to evaluate the safety and feasibility of MSC treatment of kidneys during NMP using a porcine autotransplantation model, and examine potential MSC treatment-associated kidney improvements up to 14 days posttransplant. After 75 min of kidney warm ischemia, four experimental groups of n = 7 underwent 14 h of oxygenated hypothermic machine perfusion. In three groups this was followed by 240 min of NMP with infusion of vehicle, 10 million porcine, or 10 million human adipose-derived MSCs. All kidneys were autotransplanted after contralateral nephrectomy. MSC treatment did not affect perfusion hemodynamics during NMP or cause adverse effects at reperfusion, with 100% animal survival. MSCs did not affect plasma creatinine, glomerular filtration rate, neutrophil gelatinase-associated lipocalin concentrations or kidney damage assessed by histology during the 14 days, and MSCs retention was demonstrated in renal cortex. Infusing MSCs during ex vivo NMP of porcine kidneys was safe and feasible. Within the short posttransplant follow-up period, no beneficial effects of ex vivo MSC therapy could be demonstrated.

Reparative effect of mesenchymal stromal cells on endothelial cells after hypoxic and inflammatory injury.

BACKGROUND: The renal endothelium is a prime target for ischemia-reperfusion injury (IRI) during donation and transplantation procedures. Mesenchymal stromal cells (MSC) have been shown to ameliorate kidney function after IRI. However, whether this involves repair of the endothelium is not clear. Therefore, our objective is to study potential regenerative effects of MSC on injured endothelial cells and to identify the molecular mechanisms involved. METHODS: Human umbilical vein endothelial cells (HUVEC) were submitted to hypoxia and reoxygenation and TNF-α treatment. To determine whether physical interaction or soluble factors released by MSC were responsible for the potential regenerative effects of MSC on endothelial cells, dose-response experiments were performed in co-culture and transwell conditions and with secretome-deficient MSC. RESULTS: MSC showed increased migration and adhesion to injured HUVEC, mediated by CD29 and CD44 on the MSC membrane. MSC decreased membrane injury marker expression, oxidative stress levels, and monolayer permeability of injured HUVEC, which was observed only when allowing both physical and paracrine interaction between MSC and HUVEC. Furthermore, viable MSC in direct contact with injured HUVEC improved wound healing capacity by 45% and completely restored their angiogenic capacity. In addition, MSC exhibited an increased ability to migrate through an injured HUVEC monolayer compared to non-injured HUVEC in vitro. CONCLUSIONS: These results show that MSC have regenerative effects on injured HUVEC via a mechanism which requires both physical and paracrine interaction. The identification of specific effector molecules involved in MSC-HUVEC interaction will allow targeted modification of MSC to apply and enhance the therapeutic effects of MSC in IRI.

Infusing Mesenchymal Stromal Cells into Porcine Kidneys during Normothermic Machine Perfusion: Intact MSCs Can Be Traced and Localised to Glomeruli.

Normothermic machine perfusion (NMP) of kidneys offers the opportunity to perform active interventions, such as the addition of mesenchymal stromal cells (MSCs), to an isolated organ prior to transplantation. The purpose of this study was to determine whether administering MSCs to kidneys during NMP is feasible, what the effect of NMP is on MSCs and whether intact MSCs are retained in the kidney and to which structures they home. Viable porcine kidneys were obtained from a slaughterhouse. Kidneys were machine perfused during 7 h at 37 °C. After 1 h of perfusion either 0, 105, 106 or 107 human adipose tissue derived MSCs were added. Additional ex vivo perfusions were conducted with fluorescent pre-labelled bone-marrow derived MSCs to assess localisation and survival of MSCs during NMP. After NMP, intact MSCs were detected by immunohistochemistry in the lumen of glomerular capillaries, but only in the 107 MSC group. The experiments with fluorescent pre-labelled MSCs showed that only a minority of glomeruli were positive for infused MSCs and most of these glomeruli contained multiple MSCs. Flow cytometry showed that the number of infused MSCs in the perfusion circuit steeply declined during NMP to approximately 10%. In conclusion, the number of circulating MSCs in the perfusate decreases rapidly in time and after NMP only a small portion of the MSCs are intact and these appear to be clustered in a minority of glomeruli.

Mesenchymal Stromal Cells Are Retained in the Porcine Renal Cortex Independently of Their Metabolic State After Renal Intra-Arterial Infusion.

The regenerative capacities of mesenchymal stromal cells (MSCs) make them suitable for renal regenerative therapy. The most common delivery route of MSC is through intravenous infusion, which is associated with off-target distribution. Renal intra-arterial delivery offers a targeted therapy, but limited knowledge is available regarding the fate of MSCs delivered through this route. Therefore, we studied the efficiency and tissue distribution of MSCs after renal intra-arterial delivery to a porcine renal ischemia-reperfusion model. MSCs were isolated from adipose tissue of healthy male pigs, fluorescently labeled and infused into the renal artery of female pigs. Flow cytometry allowed MSC detection and quantification in tissue and blood. In addition, quantitative polymerase chain reaction was used to trace MSCs by their Y-chromosome. During infusion, a minor number of MSCs left the kidney through the renal vein, and no MSCs were identified in arterial blood. Ischemic and healthy renal tissues were analyzed 30 min and 8 h after infusion, and 1-4 × 104 MSCs per gram of tissue were detected, predominantly, in the renal cortex, with a viability >70%. Confocal microscopy demonstrated mainly glomerular localization of MSCs, but they were also observed in the capillary network around tubuli. The infusion of heat-inactivated (HI) MSCs, which are metabolically inactive, through the renal artery showed that HI-MSCs were distributed in the kidney in a similar manner to regular MSCs, suggesting a passive retention mechanism. Long-term MSC survival was analyzed by Y-chromosome tracing, and demonstrated that a low percentage of the infused MSCs were present in the kidney 14 days after administration, while HI-MSCs were completely undetectable. In conclusion, renal intra-arterial MSC infusion limited off-target engraftment, leading to efficient MSC delivery to the kidney, most of them being cleared within 14 days. MSC retention was independent of the metabolic state of MSC, indicating a passive mechanism.

Effects of Normothermic Machine Perfusion Conditions on Mesenchymal Stromal Cells.

Ex-situ normothermic machine perfusion (NMP) of transplant kidneys allows assessment of kidney quality and targeted intervention to initiate repair processes prior to transplantation. Mesenchymal stromal cells (MSC) have been shown to possess the capacity to stimulate kidney repair. Therefore, the combination of NMP and MSC therapy offers potential to repair transplant kidneys. It is however unknown how NMP conditions affect MSC. In this study the effect of NMP perfusion fluid on survival, metabolism and function of thawed cryopreserved human (h)MSC and porcine (p)MSC in suspension conditions was studied. Suspension conditions reduced the viability of pMSC by 40% in both perfusion fluid and culture medium. Viability of hMSC was reduced by suspension conditions by 15% in perfusion fluid, whilst no differences were found in survival in culture medium. Under adherent conditions, survival of the cells was not affected by perfusion fluid. The perfusion fluid did not affect survival of fresh MSC in suspension compared to the control culture medium. The freeze-thawing process impaired the survival of hMSC; 95% survival of fresh hMSC compared to 70% survival of thawed hMSC. Moreover, thawed MSC showed increased levels of reactive oxygen species, which indicates elevated levels of oxidative stress, and reduced mitochondrial activity, which implies reduced metabolism. The adherence of pMSC and hMSC to endothelial cells was reduced after the thawing process, effect which was particularly profound in in the perfusion fluid. To summarize, we observed that conditions required for machine perfusion are influencing the behavior of MSC. The freeze-thawing process reduces survival and metabolism and increases oxidative stress, and diminishes their ability to adhere to endothelial cells. In addition, we found that hMSC and pMSC behaved differently, which has to be taken into consideration when translating results from animal experiments to clinical studies.

Immunomodulation By Therapeutic Mesenchymal Stromal Cells (MSC) Is Triggered Through Phagocytosis of MSC By Monocytic Cells.

Mesenchymal stem or stromal cells (MSC) are under investigation as a potential immunotherapy. MSC are usually administered via intravenous infusion, after which they are trapped in the lungs and die and disappear within a day. The fate of MSC after their disappearance from the lungs is unknown and it is unclear how MSC realize their immunomodulatory effects in their short lifespan. We examined immunological mechanisms determining the fate of infused MSC and the immunomodulatory response associated with it. Tracking viable and dead human umbilical cord MSC (ucMSC) in mice using Qtracker beads (contained in viable cells) and Hoechst33342 (staining all cells) revealed that viable ucMSC were present in the lungs immediately after infusion. Twenty-four hours later, the majority of ucMSC were dead and found in the lungs and liver where they were contained in monocytic cells of predominantly non-classical Ly6Clow phenotype. Monocytes containing ucMSC were also detected systemically. In vitro experiments confirmed that human CD14++ /CD16- classical monocytes polarized toward a non-classical CD14++ CD16+ CD206+ phenotype after phagocytosis of ucMSC and expressed programmed death ligand-1 and IL-10, while TNF-α was reduced. ucMSC-primed monocytes induced Foxp3+ regulatory T cell formation in mixed lymphocyte reactions. These results demonstrate that infused MSC are rapidly phagocytosed by monocytes, which subsequently migrate from the lungs to other body sites. Phagocytosis of ucMSC induces phenotypical and functional changes in monocytes, which subsequently modulate cells of the adaptive immune system. It can be concluded that monocytes play a crucial role in mediating, distributing, and transferring the immunomodulatory effect of MSC. Stem Cells 2018;36:602-615.

Mesenchymal Stromal Cells as Anti-Inflammatory and Regenerative Mediators for Donor Kidneys During Normothermic Machine Perfusion.

There is great demand for transplant kidneys for the treatment of end-stage kidney disease patients. To expand the donor pool, organs from older and comorbid brain death donors, so-called expanded criteria donors (ECD), as well as donation after circulatory death donors, are considered for transplantation. However, the quality of these organs may be inferior to standard donor organs. A major issue affecting graft function and survival is ischemia/reperfusion injury, which particularly affects kidneys from deceased donors. The development of hypothermic machine perfusion has been introduced in kidney transplantation as a preservation technique and has improved outcomes in ECD and marginal organs compared to static cold storage. Normothermic machine perfusion (NMP) is the most recent evolution of perfusion technology and allows assessment of the donor organ before transplantation. The possibility to control the content of the perfusion fluid offers opportunities for damage control and reparative therapies during machine perfusion. Mesenchymal stromal cells (MSC) have been demonstrated to possess potent regenerative properties via the release of paracrine effectors. The combination of NMP and MSC administration at the same time is a promising procedure in the field of transplantation. Therefore, the MePEP consortium has been created to study this novel modality of treatment in preparation for human trials. MePEP aims to assess the therapeutic effects of MSC administered ex vivo by NMP in the mechanisms of injury and repair in a porcine kidney autotransplantation model.

Biomineralization of carbonates by Halobacillus trueperi in solid and liquid media with different salinities.

We investigated the precipitation of carbonates by Halobacillus trueperi in both solid and liquid media at different salt concentrations and different magnesium/calcium ratios. H. trueperi precipitated at all assayed salt concentrations. When salt concentration increased, the quantity and the size of bioliths decreased and the time required increased. The precipitated minerals (determined by X-ray diffraction) were calcite, magnesium calcite and monohydrocalcite in variable proportions depending on the salinity and the physical state of the medium; the magnesium content of the magnesium calcites also varied with regard to the culture type. According to the saturation indices other minerals could also precipitate. Scanning electron microscopy showed that dominant morphologies of the bioliths were spherulitic with fibrous radiated interiors. We show that H. trueperi plays an active role in the precipitation of carbonates and we hypothesize about this process of biomineralization.