Assessing the functional heterogeneity of human perivascular cells

Perivascular cells found in multiple organs give rise to mesenchymal stromal/stem cells or MSCs in vitro. These include adventitial cells (CD34+ CD146- CD31- CD45-) isolated from large vessels and pericytes (CD34- CD146+ CD31-CD45-) found in small vessels and capillaries. Both populations play a key role in tissue remodelling during injury and disease and display phenotypic and functional heterogeneity. However, specific stem cell properties of both populations are unknown. During my PhD, I have identified aldehyde dehydrogenase (ALDH) activity as a marker of stem cell-like perivascular cells. We performed RNA sequencing on perivascular cells isolated based upon high- or low ALDH activity. I found transcriptional differences that suggest different functions in vivo including progenitor capacity and interaction with the immune system. Interestingly, I found that ALDH1A1, which has been associated with stem cell properties, is the main isoform present in ALDH high adventitial cells suggesting their involvement in the regeneration process post-tissue injury. Whether these cells change in culture remains unclear. I found that ALDH subsets isolated from adventitial cells become similar both transcriptionally and functionally upon expansion in MSC culture. Conversely, pericytes seem to maintain a different identity compared to adventitial cells in vitro. I next analysed ALDH1A1 expression in pathological tissues. In human glioblastoma, I found that ALDH1A1 expression in perivascular cells changes suggesting their involvement in angiogenesis and tumour growth. Compared to control, skeletal muscle in mice post-injury showed changes in ALDH1A1 expression distribution, suggesting their contribution to the regeneration process. In conclusion, my results show that ALDH high adventitial cells in large vessels mark a population of MSC progenitors expressing genes involved in processes such as angiogenesis and, matrix remodelling, amongst others. Importantly, I documented how culture conditions change these perivascular cells once they become MSCs in vitro. Finally, I showed that ALDH1A1 expression and cell distribution in disease or after injury is altered

Diseño conceptual, preliminar y detallado del cohete sonda recuperable “aristarco i” propulsado con propelente sólido.

En el presente documento se encuentra el desarrollo del diseño conceptual, preliminar y detallado de un cohete sonda propulsado por propelente sólido, llamado ARISTARCO I, cuya misión principal es la obtención de datos atmosféricos (presión y temperatura) por encima de un kilómetro de altitud; sin embargo, a partir de los sistemas desarrollados, el cohete a su vez puede realizar mediciones de altitud, tiempo, aceleración e inclinación del vehículo. Inicialmente se conceptualizan los componentes del cohete, y a través de variables cualitativas, se determina el tipo de cada uno de los componentes que serán implementados en el vehículo. Posteriormente se realiza el diseño preliminar, en el cual se dimensionan y evalúan los componentes que conforman el ARISTARCO I. De esta manera se conocen de forma cuantitativa, parámetros fundamentales en el desarrollo de la misión del cohete

Protocol to analyze and validate transcriptomic changes in PDGFRβ-KO mesenchymal stem cell osteogenic potential in the mouse embryo

Mesenchymal stem/stromal cells (MSCs) can differentiate into osteoblasts under appropriate conditions. PDGFRβ signaling controls MSC osteogenic potential both transcriptomically and in culture. Here, we present a “computer to the bench” protocol to analyze changes in MSC osteogenic potential at transcriptomic and cellular level in the absence of PDGFRβ. We detail the preparation of cells from mouse embryos, the analysis of transcriptomic changes from single-cell RNA-sequencing data, the procedure for MSC derivation and culture, and an osteogenic assay for functional validation. For complete details on the use and execution of this protocol, please refer to Sá da Bandeira et al. (2022).(1

Bone-forming perivascular cells: Cellular heterogeneity and use for tissue repair

: Mesenchymal progenitor cells are broadly distributed across perivascular niches-an observation conserved between species. One common histologic zone with a high frequency of mesenchymal progenitor cells within mammalian tissues is the tunica adventitia, the outer layer of blood vessel walls populated by cells with a fibroblastic morphology. The diversity and functions of (re)generative cells present in this outermost perivascular niche are under intense investigation; we have reviewed herein our current knowledge of adventitial cell potential with a somewhat narrow focus on bone formation. Antigens of interest to functionally segregate adventicytes are discussed, including CD10, CD107a, aldehyde dehydrogenase isoforms, and CD140a, among others. Purified adventicytes (such as CD10+ , CD107alow , and CD140a+ cells) have stronger osteogenic potential and promote bone formation in vivo. Recent bone tissue engineering applications of adventitial cells are also presented. A better understanding of perivascular progenitor cell subsets may represent a beneficial advance for future efforts in tissue repair and bioengineering

Runx1+ vascular smooth muscle cells are essential for hematopoietic stem and progenitor cell development in vivo

Hematopoietic stem cells (HSCs) produce all essential cellular components of the blood. Stromal cell lines supporting HSCs follow a vascular smooth muscle cell (vSMC) differentiation pathway, suggesting that some hematopoiesis-supporting cells originate from vSMC precursors. These pericyte-like precursors were recently identified in the aorta-gonad-mesonephros (AGM) region; however, their role in the hematopoietic development in vivo remains unknown. Here, we identify a subpopulation of NG2 +Runx1 + perivascular cells that display a sclerotome-derived vSMC transcriptomic profile. We show that deleting Runx1 in NG2 + cells impairs the hematopoietic development in vivo and causes transcriptional changes in pericytes/vSMCs, endothelial cells and hematopoietic cells in the murine AGM. Importantly, this deletion leads also to a significant reduction of HSC reconstitution potential in the bone marrow in vivo. This defect is developmental, as NG2 +Runx1 + cells were not detected in the adult bone marrow, demonstrating the existence of a specialised pericyte population in the HSC-generating niche, unique to the embryo. </p

In vivo biocompatibility testing of nanoparticle-functionalized alginate–chitosan scaffolds for tissue engineering applications

Background: There is a strong interest in designing new scaffolds for their potential application in tissue engineering and regenerative medicine. The incorporation of functionalization molecules can lead to the enhancement of scaffold properties, resulting in variations in scaffold compatibility. Therefore, the efficacy of the therapy could be compromised by the foreign body reaction triggered after implantation.Methods: In this study, the biocompatibilities of three scaffolds made from an alginate–chitosan combination and functionalized with gold nanoparticles (AuNp) and alginate-coated gold nanoparticles (AuNp + Alg) were evaluated in a subcutaneous implantation model in Wistar rats. Scaffolds and surrounding tissue were collected at 4-, 7- and 25-day postimplantation and processed for histological analysis and quantification of the expression of genes involved in angiogenesis, macrophage profile, and proinflammatory (IL-1β and TNFα) and anti-inflammatory (IL-4 and IL-10) cytokines.Results: Histological analysis showed a characteristic foreign body response that resolved 25 days postimplantation. The intensity of the reaction assessed through capsule thickness was similar among groups. Functionalizing the device with AuNp and AuNp + Alg decreased the expression of markers associated with cell death by apoptosis and polymorphonuclear leukocyte recruitment, suggesting increased compatibility with the host tissue. Similarly, the formation of many foreign body giant cells was prevented. Finally, an increased detection of alpha smooth muscle actin was observed, showing the angiogenic properties of the elaborated scaffolds.Conclusion: Our results show that the proposed scaffolds have improved biocompatibility and exhibit promising potential as biomaterials for elaborating tissue engineering constructs

TCR-stimulated changes in cell surface CD46 expression generate type 1 regulatory T cells

International audienc

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principle calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI. Supplemental material in the ancillary file

Microglia Are Mediators of Borrelia burgdorferi–Induced Apoptosis in SH-SY5Y Neuronal Cells

Inflammation has long been implicated as a contributor to pathogenesis in many CNS illnesses, including Lyme neuroborreliosis. Borrelia burgdorferi is the spirochete that causes Lyme disease and it is known to potently induce the production of inflammatory mediators in a variety of cells. In experiments where B. burgdorferi was co-cultured in vitro with primary microglia, we observed robust expression and release of IL-6 and IL-8, CCL2 (MCP-1), CCL3 (MIP-1α), CCL4 (MIP-1β) and CCL5 (RANTES), but we detected no induction of microglial apoptosis. In contrast, SH-SY5Y (SY) neuroblastoma cells co-cultured with B. burgdorferi expressed negligible amounts of inflammatory mediators and also remained resistant to apoptosis. When SY cells were co-cultured with microglia and B. burgdorferi, significant neuronal apoptosis consistently occurred. Confocal microscopy imaging of these cell cultures stained for apoptosis and with cell type-specific markers confirmed that it was predominantly the SY cells that were dying. Microarray analysis demonstrated an intense microglia-mediated inflammatory response to B. burgdorferi including up-regulation in gene transcripts for TLR-2 and NFκβ. Surprisingly, a pathway that exhibited profound changes in regard to inflammatory signaling was triggering receptor expressed on myeloid cells-1 (TREM1). Significant transcript alterations in essential p53 pathway genes also occurred in SY cells cultured in the presence of microglia and B. burgdorferi, which indicated a shift from cell survival to preparation for apoptosis when compared to SY cells cultured in the presence of B. burgdorferi alone. Taken together, these findings indicate that B. burgdorferi is not directly toxic to SY cells; rather, these cells become distressed and die in the inflammatory surroundings generated by microglia through a bystander effect. If, as we hypothesized, neuronal apoptosis is the key pathogenic event in Lyme neuroborreliosis, then targeting microglial responses may be a significant therapeutic approach for the treatment of this form of Lyme disease