Herb-Derived Products: Natural Tools to Delay and Counteract Stem Cell Senescence

Mitigating Oxidative Stress in Perinatal Cells: A Critical Step toward an Optimal Therapeutic Use in Regenerative Medicine

Oxidative stress (OS) occurs when the production of reactive oxygen species (ROS) is not balanced by the body's antioxidant defense system. OS can profoundly affect cellular health and function. ROS can have a profound negative impact on cells that undergo a predestined and time-regulated process of proliferation or differentiation, such as perinatal stem cells. Due to the large-scale employment of these immunotolerant stem cells in regenerative medicine, it is important to reduce OS to prevent them from losing function and increase their application in the regenerative medicine field. This goal can be achieved through a variety of strategies, such as the use of antioxidants and other compounds that can indirectly modulate the antioxidant defense system by enhancing cellular stress response pathways, including autophagy and mitochondrial function, thereby reducing ROS levels. This review aims to summarize information regarding OS mechanisms in perinatal stem cells and possible strategies for reducing their deleterious effects.

Plumbagin, a Natural Compound with Several Biological Effects and Anti-Inflammatory Properties

Phytochemicals from various medicinal plants are well known for their antioxidant properties and anti-cancer effects. Many of these bioactive compounds or natural products have demonstrated effects against inflammation, while some showed a role that is only approximately described as anti-inflammatory. In particular, naphthoquinones are naturally-occurring compounds with different pharmacological activities and allow easy scaffold modification for drug design approaches. Among this class of compounds, Plumbagin, a plant-derived product, has shown interesting counteracting effects in many inflammation models. However, scientific knowledge about the beneficial effect of Plumbagin should be comprehensively reported before candidating this natural molecule into a future drug against specific human diseases. In this review, the most relevant mechanisms in which Plumbagin plays a role in the process of inflammation were summarized. Other relevant bioactive effects were reviewed to provide a complete and compact scenario of Plumbagin's potential therapeutic significance.

Cytochalasin B Influences Cytoskeletal Organization and Osteogenic Potential of Human Wharton's Jelly Mesenchymal Stem Cells

Among perinatal stem cells of the umbilical cord, human Wharton's jelly mesenchymal stem cells (hWJ-MSCs) are of great interest for cell-based therapy approaches in regenerative medicine, showing some advantages over other MSCs. In fact, hWJ-MSCs, placed between embryonic and adult MSCs, are not tumorigenic and are harvested with few ethical concerns. Furthermore, these cells can be easily cultured in vitro, maintaining both stem properties and a high proliferative rate for several passages, as well as trilineage capacity of differentiation. Recently, it has been demonstrated that cytoskeletal organization influences stem cell biology. Among molecules able to modulate its dynamics, Cytochalasin B (CB), a cyto-permeable mycotoxin, influences actin microfilament polymerization, thus affecting several cell properties, such as the ability of MSCs to differentiate towards a specific commitment. Here, we investigated for the first time the effects of a 24 h-treatment with CB at different concentrations (0.1-3 μM) on hWJ-MSCs. CB influenced the cytoskeletal organization in a dose-dependent manner, inducing changes in cell number, proliferation, shape, and nanomechanical properties, thus promoting the osteogenic commitment of hWJ-MSCs, as confirmed by the expression analysis of osteogenic/autophagy markers.

Cytochalasin B Modulates Nanomechanical Patterning and Fate in Human Adipose-Derived Stem Cells

Cytoskeletal proteins provide architectural and signaling cues within cells. They are able to reorganize themselves in response to mechanical forces, converting the stimuli received into specific cellular responses. Thus, the cytoskeleton influences cell shape, proliferation, and even differentiation. In particular, the cytoskeleton affects the fate of mesenchymal stem cells (MSCs), which are highly attractive candidates for cell therapy approaches due to their capacity for self-renewal and multi-lineage differentiation. Cytochalasin B (CB), a cyto-permeable mycotoxin, is able to inhibit the formation of actin microfilaments, resulting in direct effects on cell biological properties. Here, we investigated for the first time the effects of different concentrations of CB (0.1–10 μM) on human adipose-derived stem cells (hASCs) both after 24 h (h) of CB treatment and 24 h after CB wash-out. CB influenced the metabolism, proliferation, and morphology of hASCs in a dose-dependent manner, in association with progressive disorganization of actin microfilaments. Furthermore, the removal of CB highlighted the ability of cells to restore their cytoskeletal organization. Finally, atomic force microscopy (AFM) revealed that cytoskeletal changes induced by CB modulated the viscoelastic properties of hASCs, influencing their stiffness and viscosity, thereby affecting adipogenic fate.

Thymoquinone-Mediated Modulation of Toll-like Receptors and Pluripotency Factors in Gingival Mesenchymal Stem/Progenitor Cells

Thymoquinone (TQ), the key active component of Nigella sativa (NS), demonstrates very promising biomedical anti-inflammatory, antioxidant, antimicrobial and anticancer properties. Several investigations have inspected the modulative activities of TQ on different stem/progenitor cell types, but its possible role in the regulation of gingival mesenchymal stem/progenitor cells (G-MSCs) has not yet been characterized. For the first time, this study investigates the effects of TQ on G-MSCs’ stemness and Toll-like receptor expression profiles. G-MSCs (n = 5) were isolated, sorted via anti-STRO-1 antibodies and then disseminated on cell culture dishes to create colony-forming units (CFUs), and their stem/progenitor cell attributes were characterized. TQ stimulation of the G-MSCs was performed, followed by an examination of the expression of pluripotency-related factors using RT-PCR and the expression profiles of TLRs 1−10 using flowcytometry, and they were compared to a non-stimulated control group. The G-MSCs presented all the predefined stem/progenitor cells’ features. The TQ-activated G-MSCs displayed significantly higher expressions of TLR3 and NANOG with a significantly reduced expression of TLR1 (p < 0.05, Wilcoxon signed-rank test). TQ-mediated stimulation preserves G-MSCs’ pluripotency and facilitates a cellular shift into an immunocompetent-differentiating phenotype through increased TLR3 expression. This characteristic modulation might impact the potential therapeutic applications of G-MSCs.

A Tailored Lipid Supplement Restored Membrane Fatty Acid Composition and Ameliorates In Vitro Biological Features of Human Amniotic Epithelial Cells

Cell culture conditions influence several biological and biochemical features of stem cells (SCs), including the membrane lipid profile, thus limiting the use of SCs for cell therapy approaches. The present study aims to investigate whether the in vitro culture may alter the membrane fatty acid signature of human Amniotic Epithelial Cells (hAECs). The analysis of the membrane fatty acid composition of hAECs cultured in basal medium showed a loss in polyunsaturated fatty acids (PUFA), in particular in omega-6 (ω-6) content, compared to freshly isolated hAECs. The addition to the basal culture medium of a chemically defined and animal-free tailored lipid supplement, namely Refeed^®, partially restored the membrane fatty acid signature of hAECs. Although the amelioration of the membrane composition did not prolong hAECs culture lifespan, Refeed^® influenced cell morphology, counteracted the onset of senescence, and increased the migratory capacity as well as the ability of hAECs to inhibit Peripheral Blood Mononuclear Cell (PBMC) proliferation. This study provides new information on hAEC features during culture passages and demonstrates that the maintenance of the membrane fatty acid signature preserved higher cell quality during in vitro expansion, suggesting the use of lipid supplementation for SC expansion in cell-based therapies.

Curcumin Alleviates the Senescence of Canine Bone Marrow Mesenchymal Stem Cells during In Vitro Expansion by Activating the Autophagy Pathway

Senescence in mesenchymal stem cells (MSCs) not only hinders the application of MSCs in regenerative medicine but is also closely correlated with biological aging and the development of degenerative diseases. In this study, we investigated the anti-aging effects of curcumin (Cur) on canine bone marrow-derived MSCs (cBMSCs), and further elucidated the potential mechanism of action based on the modulation of autophagy. cBMSCs were expanded in vitro with standard procedures to construct a cell model of premature senescence. Our evidence indicates that compared with the third passage of cBMSCs, many typical senescence-associated phenotypes were observed in the sixth passage of cBMSCs. Cur treatment can improve cBMSC survival and retard cBMSC senescence according to observations that Cur (1 μM) treatment can improve the colony-forming unit-fibroblasts (CFU-Fs) efficiency and upregulated the mRNA expression of pluripotent transcription factors (SOX-2 and Nanog), as well as inhibiting the senescence-associated beta-galactosidase (SA-β-gal) activities and mRNA expression of the senescence-related markers (p16 and p21) and pro-inflammatory molecules (tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)). Furthermore, Cur (0.1 μM~10 μM) was observed to increase autophagic activity, as identified by upregulation of microtubule-associated protein 1 light chain 3 (LC3), unc51-like autophagy-activating kinase-1 (ULK1), autophagy-related gene (Atg) 7 and Atg12, and the generation of type II of light chain 3 (LC3-II), thereby increasing autophagic vacuoles and acidic vesicular organelles, as well as causing a significant decrease in the p62 protein level. Moreover, the autophagy activator rapamycin (RAP) and Cur were found to partially ameliorate the senescent features of cBMSCs, while the autophagy inhibitor 3-methyladenine (3-MA) was shown to aggravate cBMSCs senescence and Cur treatment was able to restore the suppressed autophagy and counteract 3-MA-induced cBMSC senescence. Hence, our study highlights the important role of Cur-induced autophagy and its effects for ameliorating cBMSC senescence and provides new insight for delaying senescence and improving the therapeutic potential of MSCs.