Anisotropic properties of elastomeric nanocomposites based on natural rubber and sp2carbon allotropes

This work provides a comprehensive investigation of the anisotropic mechanical and electrical properties of elastomeric nanocomposites based on natural rubber and sp2carbon allotropes. They can be either nanometric and with high shape anisotropy like Carbon Nanotubes (CNT) and lamellar nanographite, or nanostructured and nearly isometric like carbon black. Studies were performed on calendered and compression molded plates. A complete mechanical characterization along all main directions could be performed by a non-standard testing approach. Composites with nanometric, high aspect ratio fillers gave rise to remarkable mechanical anisotropy, revealing an orthotropic and transversally isotropic response: modulus values were very similar in the sheet plane and much larger (almost twice as much) in the orthogonal direction. The electrical anisotropy achieved its maximum at lower CNT content. Composites with carbon black did not reveal mechanical anisotropy, while, quite strikingly, a very large electrical anisotropy was observed for carbon black content close to the percolation threshold. These results provide insights into the anisotropic behavior of nanofilled elastomers, and could pave the way to their exploitation in advanced engineering design and biomimicking biomedical applications

Amniotic MSCs reduce pulmonary fibrosis by hampering lung B-cell recruitment, retention, and maturation

Growing evidence suggests a mechanistic link between inflammation and the development and progression of fibrotic processes. Mesenchymal stromal cells derived from the human amniotic membrane (hAMSCs), which display marked immunomodulatory properties, have been shown to reduce bleomycin-induced lung fibrosis in mice, possibly by creating a microenvironment able to limit the evolution of chronic inflammation to fibrosis. However, the ability of hAMSCs to modulate immune cells involved in bleomycin-induced pulmonary inflammation has yet to be elucidated. Herein, we conducted a longitudinal study of the effects of hAMSCs on alveolar and lung immune cell populations upon bleomycin challenge. Immune cells collected through bronchoalveolar lavage were examined by flow cytometry, and lung tissues were used to study gene expression of markers associated with different immune cell types. We observed that hAMSCs increased lung expression of T regulatory cell marker Foxp3, increased macrophage polarization toward an anti-inflammatory phenotype (M2), and reduced the antigen-presentation potential of macrophages and dendritic cells. For the first time, we demonstrate that hAMSCs markedly reduce pulmonary B-cell recruitment, retention, and maturation, and counteract the formation and expansion of intrapulmonary lymphoid aggregates. Thus, hAMSCs may hamper the self-maintaining inflammatory condition promoted by B cells that continuously act as antigen presenting cells for proximal T lymphocytes in injured lungs. By modulating B-cell response, hAMSCs may contribute to blunting of the chronicization of lung inflammatory processes with a consequent reduction of the progression of the fibrotic lesion

Human amniotic mesenchymal stromal cells support the ex vivo expansion of cord blood hematopoietic stem cells

Currently over 30 000 allogeneic hematopoietic stem cell (HSC) transplantations have been performed for the treatment of hematological and nonhematological diseases using HSC from umbilical cord blood (CB). However, the wide utilization of CB as a source of HSC is limited by the low number of cells recovered. One strategy to expand ex vivo CB-HSC is represented by the use of bone marrow mesenchymal stromal cells (BM-MSCs) as a feeder to enhance HSC proliferation while maintaining HSC stemness. Indeed, BM-MSCs have been recognized as one of the most relevant players in the HSC niche. Thus, it has been hypothesized that they can support the ex vivo expansion of HSC by mimicking the physiological microenvironment present in the hematopoietic niche. Due to the role of placenta in supporting fetal hematopoiesis, MSC derived from the amniotic membrane (hAMSC) of human term placenta could represent an interesting alternative to BM-MSC as a feeder layer to enhance the proliferation and maintain HSC stemness. Therefore, in this study we investigated if hAMSC could support the ex vivo expansion of HSC and progenitor cells. The capacity of hAMSCs to support the ex vivo expansion of CB-HSC was evaluated in comparison to the control condition represented by the CB-CD34+ cells without a feeder layer. The coculture was performed at two different CD34+:MSC ratios (1:2 and 1:8) in both cell-to-cell contact and transwell setting. After 7 days, the cells were collected and analyzed for phenotype and functionality. Our results suggest that hAMSCs represent a valuable alternative to BM-MSC to support: (a) the ex vivo expansion of CB-HSC in both contact and transwell systems, (b) the colony forming unit ability, and (c) long-term culture initiating cells ability. Overall, these findings may contribute to address the unmet need of high HSC content in CB units available for transplantation