Changes in the Transcriptome Profiles of Human Amnion-Derived Mesenchymal Stromal/Stem Cells Induced by Three-Dimensional Culture: A Potential Priming Strategy to Improve Their Properties

Mesenchymal stromal/stem cells (MSCs) are believed to function in vivo as a homeostatic tool that shows therapeutic properties for tissue repair/regeneration. Conventionally, these cells are expanded in two-dimensional (2D) cultures, and, in that case, MSCs undergo genotypic/phenotypic changes resulting in a loss of their therapeutic capabilities. Moreover, several clinical trials using MSCs have shown controversial results with moderate/insufficient therapeutic responses. Different priming methods were tested to improve MSC effects, and three-dimensional (3D) culturing techniques were also examined. MSC spheroids display increased therapeutic properties, and, in this context, it is crucial to understand molecular changes underlying spheroid generation. To address these limitations, we performed RNA-seq on human amnion-derived MSCs (hAMSCs) cultured in both 2D and 3D conditions and examined the transcriptome changes associated with hAMSC spheroid formation. We found a large number of 3D culture-sensitive genes and identified selected genes related to 3D hAMSC therapeutic effects. In particular, we observed that these genes can regulate proliferation/differentiation, as well as immunomodulatory and angiogenic processes. We validated RNA-seq results by qRT-PCR and methylome analysis and investigation of secreted factors. Overall, our results showed that hAMSC spheroid culture represents a promising approach to cell-based therapy that could significantly impact hAMSC application in the field of regenerative medicine.

Mesenchymal Stromal/Stem Cells-Derived Exosomes as an Antimicrobial Weapon for Orodental Infections

The oral cavity as the second most various microbial community in the body contains a broad spectrum of microorganisms which are known as the oral microbiome. The oral microbiome includes different types of microbes such as bacteria, fungi, viruses, and protozoa. Numerous factors can affect the equilibrium of the oral microbiome community which can eventually lead to orodental infectious diseases. Periodontitis, dental caries, oral leukoplakia, oral squamous cell carcinoma are some multifactorial infectious diseases in the oral cavity. In defending against infection, the immune system has an essential role. Depending on the speed and specificity of the reaction, immunity is divided into two different types which are named the innate and the adaptive responses but also there is much interaction between them. In these responses, different types of immune cells are present and recent evidence demonstrates that these cell types both within the innate and adaptive immune systems are capable of secreting some extracellular vesicles named exosomes which are involved in the response to infection. Exosomes are 30–150 nm lipid bilayer vesicles that consist of variant molecules, including proteins, lipids, and genetic materials and they have been associated with cell-to-cell communications. However, some kinds of exosomes can be effective on the pathogenicity of various microorganisms and promoting infections, and some other ones have antimicrobial and anti-infective functions in microbial diseases. These discrepancies in performance are due to the origin of the exosome. Exosomes can modulate the innate and specific immune responses of host cells by participating in antigen presentation for activation of immune cells and stimulating the release of inflammatory factors and the expression of immune molecules. Also, mesenchymal stromal/stem cells (MSCs)-derived exosomes participate in immunomodulation by different mechanisms. Ease of expansion and immunotherapeutic capabilities of MSCs, develop their applications in hundreds of clinical trials. Recently, it has been shown that cell-free therapies, like exosome therapies, by having more advantages than previous treatment methods are emerging as a promising strategy for the treatment of several diseases, in particular inflammatory conditions. In orodental infectious disease, exosomes can also play an important role by modulating immunoinflammatory responses. Therefore, MSCs-derived exosomes may have potential therapeutic effects to be a choice for controlling and treatment of orodental infectious diseases.

Mesenchymal stem/stromal cell-based therapies for severe viral pneumonia: therapeutic potential and challenges

Severe viral pneumonia is a significant cause of morbidity and mortality globally, whether due to outbreaks of endemic viruses, periodic viral epidemics, or the rarer but devastating global viral pandemics. While limited anti-viral therapies exist, there is a paucity of direct therapies to directly attenuate viral pneumonia-induced lung injury, and management therefore remains largely supportive. Mesenchymal stromal/stem cells (MSCs) are receiving considerable attention as a cytotherapeutic for viral pneumonia. Several properties of MSCs position them as a promising therapeutic strategy for viral pneumonia-induced lung injury as demonstrated in pre-clinical studies in relevant models. More recently, early phase clinical studies have demonstrated a reassuring safety profile of these cells. These investigations have taken on an added importance and urgency during the COVID-19 pandemic, with multiple trials in progress across the globe. In parallel with clinical translation, strategies are being investigated to enhance the therapeutic potential of these cells in vivo, with different MSC tissue sources, specific cellular products including cell-free options, and strategies to ‘licence’ or ‘pre-activate’ these cells, all being explored. This review will assess the therapeutic potential of MSC-based therapies for severe viral pneumonia. It will describe the aetiology and epidemiology of severe viral pneumonia, describe current therapeutic approaches, and examine the data suggesting therapeutic potential of MSCs for severe viral pneumonia in pre-clinical and clinical studies. The challenges and opportunities for MSC-based therapies will then be considered.

Human adipose-derived stromal/stem cells expressing doublecortin improve cartilage repair in rabbits and monkeys

Localized cartilage lesions in early osteoarthritis and acute joint injuries are usually treated surgically to restore function and relieve pain. However, a persistent clinical challenge remains in how to repair the cartilage lesions. We expressed doublecortin (DCX) in human adipose-derived stromal/stem cells (hASCs) and engineered hASCs into cartilage tissues using an in vitro 96-well pellet culture system. The cartilage tissue constructs with and without DCX expression were implanted in the knee cartilage defects of rabbits (n = 42) and monkeys (n = 12). Cohorts of animals were euthanized at 6, 12, and 24 months after surgery to evaluate the cartilage repair outcomes. We found that DCX expression in hASCs increased expression of growth differentiation factor 5 (GDF5) and matrilin 2 in the engineered cartilage tissues. The cartilage tissues with DCX expression significantly enhanced cartilage repair as assessed macroscopically and histologically at 6, 12, and 24 months after implantation in the rabbits and 24 months after implantation in the monkeys, compared to the cartilage tissues without DCX expression. These findings suggest that hASCs expressing DCX may be engineered into cartilage tissues that can be used to treat localized cartilage lesions.

Silk Fibroin Scaffolds as Biomaterials for 3D Mesenchymal Stromal Cells Cultures

Silk fibroin (SF), a protein-based fiber extracted from Bombyx mori cocoons, has recently emerged with great potential for the biomedical field to be used as a biomaterial processable in a variety of formats and applications, due to its natural characteristics. The aims of the present study were to characterize the structural properties of the SF scaffolds, in the format of porous sponges, and to investigate their feasibility to support the adhesion of mesenchymal stromal/stem cells isolated from human Wharton’s jelly of the umbilical cord (WJ-MSC). Adhesion is a prerequisite for using the SF scaffold as biomaterial for supporting three-dimensional (3D) WJ-MSC cultures for several applications. The integration among micro-computed tomography, confocal analysis, and field emission scanning electron microscopy allowed carrying out a deep investigation based on quantitative morphological parameters and qualitative observations at high resolution. High levels of porosity, interconnection, and contact surface–volume ratio confirmed the appropriateness of the designed SF porous scaffolds as supports for cell cultures. WJ-MSC was demonstrated to be capable of adhering to and colonizing the SF scaffold applicable as a 3D cell culture system, of conducting in vitro experiments in a more controlled environment, and possibly of being used in tissue engineering, regenerative medicine, and applications in oncology.

Proliferative Effect of Aqueous Extract of Sea Cucumber (Holothuria Parva) Body Wall on Human Umbilical Cord Mesenchymal Stromal/stem Cells

Background: The sea cucumber potentials for stem cell proliferation induction and their mechanisms of bioactive compounds in its extract have been studied. Human umbilical cord mesenchymal stromal/stem cells (hUC-MSCs) were exposed to aqueous extract of Holothuria parva body wall. Methods: Using GC-MS analysis on aqueous extract of H. parva, proliferative molecules were detected. The extract concentrations of 5, 10, 20, 40, and 80 µg/mL and 10 and 20 ng/mL of human epidermal growth factor (EGF) as positive controls were used. MTT proliferation, cell count, viability, and cell cycle assays were performed. Using Western blot analysis, effects of aqueous extract of H. parva and EGF on cell proliferation markers were detected. Computational modeling done to detect effective proliferative compounds in aqueous extract of H. parva. Results: MTT assay showed that the 10, 20, and 40 µg/mL aqueous extract of H. parva had proliferative effects on hUC-MSCs. Count of the cells treated with the 20 µg/mL of the extract was increased faster and higher than the control group (P<0.05). This concentration of extract did not have significant effects on hUC-MSCs viability. The cell cycle assay of hUC-MSCs showed that percent of cells in the G2 stage of the extract was biologically higher than the control group (P>0.05). Expression of the cyclin D1, cyclin D3, cyclin E, HIF-1α, and TERT were increased comparing with the control group. Moreover, expression of the p21 and PCNA decreased after treating hUC-MSCs with the extract. However, the CDC-2/cdk-1 and ERK1/2 had almost the same expression as the control group. The expression of the cdk-4 and cdk-6 was decreased after treatment with the extract. Between the detected compounds, 1-methyl-4-(1-methylethenyl)-benzene showed better affinity to cdk-4 and p21 than tetradecanoic acid. Conclusions: The H. parva aqueous extract showed proliferative potential on the hUC-MSCs.

Tumorigenic Aspects of MSC Senescence—Implication in Cancer Development and Therapy

As an organism ages, many physiological processes change, including the immune system. This process, called immunosenescence, characterized by abnormal activation and imbalance of innate and adaptive immunity, leads to a state of chronic low-grade systemic inflammation, termed inflammaging. Aging and inflammaging are considered to be the root of many diseases of the elderly, as infections, autoimmune and chronic inflammatory diseases, degenerative diseases, and cancer. The role of mesenchymal stromal/stem cells (MSCs) in the inflammaging process and the age-related diseases is not completely established, although numerous features of aging MSCs, including altered immunomodulatory properties, impeded MSC niche supporting functions, and senescent MSC secretory repertoire are consistent with inflammaging development. Although senescence has its physiological function and can represent a mechanism of tumor prevention, in most cases it eventually transforms into a deleterious (para-)inflammatory process that promotes tumor growth. In this review we are going through current literature, trying to explore the role of senescent MSCs in making and/or sustaining a microenvironment permissive to tumor development and to analyze the therapeutic options that could target this process.