Mesenchymal stem cells: Cell therapy and regeneration potential

Prenatal Neural Tube Anomalies: A Decade of Intrauterine Stem Cell Transplantation Using Advanced Tissue Engineering Methods

Neural tube defects (NTDs) are among the most common congenital defects during neurulation. Spina bifida is a type of NTD that can occur in different forms. Since myelomeningocele (MMC) is the most severe form of spina bifida, finding a satisfactory treatment for MMC is a gold standard for the treatment of spina bifida. The Management of Myelomeningocele Study (MOMS) demonstrated that intrauterine treatment of spina bifida could ameliorate the complications associated with spina bifida and would also reduce the placement of ventriculoperitoneal (VP) shunt by 50%. Recently developed tissue engineering (TE) approaches using scaffolds, stem cells, and growth factors allow treatment of the fetus with minimally invasive methods and promising outcomes. The application of novel patches with appropriate stem cells and growth factors leads to better coverage of the defect with fewer complications. These approaches with less invasive surgical procedures, even in animal models with similar characteristics as the human MMC defect, paves the way for the modern application of less invasive surgical methods. Significantly, the early detection of these problems and applying these approaches can increase the potential efficacy of MMC treatment with fewer complications. However, further studies should be conducted to find the most suitable scaffolds and stem cells, and their application should be evaluated in animal models. This review intends to discuss advanced TE methods for treating MMC and recent successes in increasing the efficacy of the treatment.

Improved Isolation of Human Vascular Wall-Resident Mesenchymal Stem Cells

Niches for tissue-resident mesenchymal stem cells (MSCs) have been identified in many adult tissues. In particular, MSCs residing in the vascular stem cell niche came into focus: the so-called vascular wall-resident MSCs (VW-MSCs) were, based upon their anatomic location, (1) distributed throughout the adult organism, and (2) supposed to be the first line cells which could be addressed in response to a pathologic trigger acting on or in close vicinity to the vascular system. Like tissue-resident MSCs in general, VW-MSC contribute to organ integrity and harbor the capacity to suppress inflammation and promote repair during normal vessel homeostasis, although resident MSCs present in the healthy situation of an individual seems not to bear sufficient for protection or repair following injury. In contrast, injury affected MSCs could contribute to disease induction and progression. A detailed understanding of the molecular repertoire as well as of the signaling pathways controlling stem cell fate of VW-MSCs is prerequisite to understand how (1) endogenous VW-MSCs contribute to normal vessel homeostasis as well as diseases that include the vascular system, (2) a potential on-site manipulation of these cells directly within their endogenous niche could be used for therapeutically benefits, and (3) isolated and therapeutically applied VW-MSCs in terms of exogenous MSCs with superior repair capabilities might be logically more efficient to address vascular diseases than MSCs derived from other tissues. This chapter describes a straightforward protocol for the improved isolation of human VW-MSCs.

Mesenchymal stem cells: Biological characteristics and application in disease therapy

Mesenchymal stem cells (MSCs) are multipotent stem cells. In addition to the capacity for self-renewal and multipotential differentiation, MSCs also have the following characteristics. MSCs can exert immunomodulatory functions through interaction with innate or adaptive immune cells, MSCs with poor immunogenicity can be used for allogeneic transplantation, and MSCs can "home" to inflammation and tumour sites. Based on these biological properties, MSCs demonstrate broad clinical application prospects in the treatment of tissue injury, autoimmune diseases, transplantation, cancer and other inflammation-related diseases. In this review we describe the biological characteristics of MSCs and discuss the research advances of MSCs in regenerative medicine, immunomodulation, oncology, and COVID-19, to fully understand the range of diseases in which MSC therapy may be beneficial.

Therapeutic Applications of Mesenchymal Stem Cells in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is an interstitial disease of unknown etiology characterized by progressive pulmonary fibrosis. Pirfenidone and nintedanib are the only drugs that can prolong the time to disease progression, slow down the decline in lung function, and prolong survival. However, they do not offer a cure and are associated with tolerability issues. The pluripotency of mesenchymal stem cells (MSCs) and their ability to regulate immunity, inhibit inflammation, and promote epithelial tissue repair highlight the promise of MSC therapy for treating interstitial lung disease. However, optimal protocols are lacking for multi-parameter selection in MSC therapy. This review summarizes preclinical studies on MSC transplantation for the treatment of interstitial lung disease and clinical studies with known results. An analysis of relevant factors for the optimization of treatment plans is presented, including MSCs with different sources, administration routes and timing, dosages, frequencies, and pretreatments with MSCs. This review proposes an optimized plan for guiding the design of future clinical research to identify therapeutic options for this complex disease.

Structure-function assessment of 3D-printed porous scaffolds by a low-cost/open source fused filament fabrication printer

Additive manufacturing encompasses a plethora of techniques to manufacture structures from a computational model. Among them, fused filament fabrication (FFF) relies on heating thermoplastics to their fusion point and extruding the material through a nozzle in a controlled pattern. FFF is a suitable technique for tissue engineering, given that allows the fabrication of 3D-scaffolds, which are utilized for tissue regeneration purposes. The objective of this study is to assess a low-cost/open-source 3D printer (In-House), by manufacturing both solid and porous samples with relevant microarchitecture in the physiological range (100-500 μm pore size), using an equivalent commercial counterpart for comparison. For this, compressive tests in solid and porous scaffolds manufactured in both printers were performed, comparing the results with finite element analysis (FEA) models. Additionally, a microarchitectural analysis was done in samples from both printers, comparing the measurements of both pore size and porosity to their corresponding computer-aided design (CAD) models. Moreover, a preliminary biological assessment was performed using scaffolds from our In-House printer, measuring cell adhesion efficiency. Finally, Fourier transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR) was performed to evaluate chemical changes in the material (polylactic acid) after fabrication in each printer. The results show that the In-House printer achieved generally better mechanical behavior and resolution capacity than its commercial counterpart, by comparing with their FEA and CAD models, respectively. Moreover, a preliminary biological assessment indicates the feasibility of the In-House printer to be used in tissue engineering applications. The results also show the influence of pore geometry on mechanical properties of 3D-scaffolds and demonstrate that properties such as the apparent elastic modulus (E_app) can be controlled in 3D-printed scaffolds.

Bone Marrow Mesenchymal Stem Cells Ameliorate Cisplatin-Induced Renal Fibrosis via miR-146a-5p/Tfdp2 Axis in Renal Tubular Epithelial Cells

Mesenchymal stem cells (MSCs) have regenerative properties in acute kidney injury (AKI). However, the potential function of MSCs in chronic kidney disease remains elusive. Renal fibrosis is the common endpoint of chronic progressive kidney diseases and causes a considerable health burden worldwide. In this study, the protective effects of bone marrow mesenchymal stem cells (BM-MSCs) were assessed in repeated administration of low-dose cisplatin-induced renal fibrosis mouse model in vivo as well as a TGF-β1-induced fibrotic model in vitro. Differentially expressed miRNAs in mouse renal tubular epithelial cells (mRTECs) regulated by BM-MSCs were screened by high-throughput sequencing. We found microRNA (miR)-146a-5p was the most significant up-regulated miRNA in mRTECs. In addition, the gene Tfdp2 was identified as one target gene of miR-146a-5p by bioinformatics analysis. The expression of Tfdp2 in the treatment of BM-MSCs on cisplatin-induced renal injury was evaluated by immunohistochemistry analysis. Our results indicate that BM-MSC attenuates cisplatin-induced renal fibrosis by regulating the miR-146a-5p/Tfdp2 axis in mRTECs.

Potential applications of deep learning in single-cell RNA sequencing analysis for cell therapy and regenerative medicine

When used in cell therapy and regenerative medicine strategies, stem cells have potential to treat many previously incurable diseases. However, current application methods using stem cells are underdeveloped, as these cells are used directly regardless of their culture medium and subgroup. For example, when using mesenchymal stem cells (MSCs) in cell therapy, researchers do not consider their source and culture method nor their application angle and function (soft tissue regeneration, hard tissue regeneration, suppression of immune function, or promotion of immune function). By combining machine learning methods (such as deep learning) with data sets obtained through single-cell RNA sequencing (scRNA-seq) technology, we can discover the hidden structure of these cells, predict their effects more accurately, and effectively use subpopulations with differentiation potential for stem cell therapy. scRNA-seq technology has changed the study of transcription, because it can express single-cell genes with single-cell anatomical resolution. However, this powerful technology is sensitive to biological and technical noise. The subsequent data analysis can be computationally difficult for a variety of reasons, such as denoising single cell data, reducing dimensionality, imputing missing values, and accounting for the zero-inflated nature. In this review, we discussed how deep learning methods combined with scRNA-seq data for research, how to interpret scRNA-seq data in more depth, improve the follow-up analysis of stem cells, identify potential subgroups, and promote the implementation of cell therapy and regenerative medicine measures.

Intrapancreatic MSC transplantation facilitates pancreatic islet regeneration

Background

Type 1 diabetes mellitus (T1D) is characterized by the autoimmune destruction of the pancreatic β cells. The transplantation of mesenchymal stromal/stem cells (MSC) was reported to rescue the damaged pancreatic niche. However, there is an ongoing discussion on whether direct physical contact between MSC and pancreatic islets results in a superior outcome as opposed to indirect effects of soluble factors released from the MSC entrapped in the lung microvasculature after systemic administration. Hence, MSC were studied in direct contact (DC) and indirect contact (IDC) with murine pancreatic β cell line MIN6-cells damaged by nitrosourea derivative streptozotocin (STZ) in vitro. Further, the protective and antidiabetic outcome of MSC transplantation was evaluated through the intrapancreatic route (IPR) and intravenous route (IVR) in STZ-induced diabetic NMRI nude mice.

Methods

MSC were investigated in culture with STZ-damaged MIN6-cells, either under direct contact (DC) or separated through a semi-permeable membrane (IDC). Moreover, multiple low doses of STZ were administered to NMRI nude mice for the induction of hyperglycemia. 0.5 × 10⁶ adipose-derived mesenchymal stem cells (ADMSC) were transferred through direct injection into the pancreas (IPR) or the tail vein (IVR), respectively. Bromodeoxyuridine (BrdU) was injected for the detection of proliferating islet cells in vivo, and real-time polymerase chain reaction (RT-PCR) was employed for the measurement of the expression of growth factor and immunomodulatory genes in the murine pancreas and human MSC. Phosphorylation of AKT and ERK was analyzed with Western blotting.

Results

The administration of MSC through IPR ameliorated hyperglycemia in contrast to IVR, STZ, and non-diabetic control in a 30-day window. IPR resulted in a higher number of replicating islet cells, number of islets, islet area, growth factor (EGF), and balancing of the Th1/Th2 response in vivo. Physical contact also provided a superior protection to MIN6-cells from STZ through the AKT and ERK pathway in vitro in comparison with IDC.

Conclusion

Our study suggests that the physical contact between MSC and pancreatic islet cells is required to fully unfold their protective potential.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02173-4.

Role of prostaglandin E2 in allogeneic mesenchymal stem cell therapy for cardiac repair

Ischemic heart disease is among the primary causes of cardiovascular-related deaths worldwide. Conventional treatments including surgical interventions and medical therapies aid in preventing further damage to heart muscle but are unable to provide a permanent solution. In recent years, stem cell therapy has emerged as an attractive alternative to restore damaged myocardium after myocardial injury. Allogeneic (donor-derived) mesenchymal stem cells (MSCs) have shown great promise in preclinical and clinical studies, making them the most widely accepted candidates for cardiac cell therapy. MSCs promote cardiac repair by modulating host immune system and secreting various soluble factors, of which prostaglandin E2 (PGE2) is an important one. PGE2 plays a significant role in regulating cardiac remodeling following myocardial injury. In this review, we provide an overview of allogeneic MSCs as candidates for myocardial regeneration with a focus on the role of the PGE2/cyclooxygenase-2 (COX2) pathway in mediating these effects.

First trimester placental mesenchymal stem cells improve cardiac function of rat after myocardial infarction via enhanced neovascularization

Acute myocardial infarction (AMI) is the most critical heart disease. Mesenchymal stem cells (MSCs) have been widely used as a therapy for AMI for several years. The human placenta has emerged as a valuable source of transplantable cells of mesenchymal origin that can be used for multiple cytotherapeutic purposes. However, the different abilities of first trimester placental chorion mesenchymal stem cells (FCMSCs) and third trimester placental chorion mesenchymal stem cells (TCMSCs) have not yet been explored. In this study, we aimed to compare the effectiveness of FCMSCs and TCMSCs on the treatment of AMI. FCMSCs and TCMSCs were isolated and characterized, and then they were subjected to in vitro endothelial cell (EC) differentiation induction and tube formation to evaluate angiogenic ability. Moreover, the in vivo effects of FCMSCs and TCMSCs on cardiac improvement were also evaluated in a rat MI model. Both FCSMCs and TCMSCs expressed a series of MSCs surface markers. After differentiation induction, FCMSCs-derived EC (FCMSCs-EC) exhibited morphology that was more similar to that of ECs and had higher CD31 and vWF levels than TCMSCs-EC. Furthermore, tube formation could be achieved by FCMSCs-EC that was significantly better than that of TCMSCs-EC. Especially, FCMSCs-EC expressed higher levels of pro-angiogenesis genes, PDGFD, VEGFA, and TNC, and lower levels of anti-angiogenesis genes, SPRY1 and ANGPTL1. In addition, cardiac improvement, indicated by left ventricular end-diastolic diameter (LVEDd), left ventricular end-systolic diameter (LVEDs), left ventricular ejection fraction (LVEF) and left ventricular shortening fraction (LVSF), could be observed following treatment with FCMSCs, and it was superior to that of TCMSCs and Bone marrow MSCs (BMSCs). FCMSCs exhibited a superior ability to generate EC differentiation, as evidenced by in vitro morphology, angiogenic potential and in vivo cardiac function improvement; further, increased levels of expression of pro-angiogenesis genes may be the mechanism by which this effect occurred.

WJMSC-derived small extracellular vesicle enhance T cell suppression through PD-L1

Both mesenchymal stem cells (MSCs) and their corresponding small extracellular vesicles (sEVs, commonly referred to as exosomes) share similar immunomodulatory properties that are potentially beneficial for the treatment of acute graft versus host disease (aGvHD). We report that clinical grade Wharton's Jelly‐derived MSCs (WJMSCs) secrete sEVs enriched in programmed death‐ligand 1 (PD‐L1), an essential ligand for an inhibitory immune checkpoint. A rapid increase in circulating sEV‐associated PD‐L1 was observed in patients with aGvHD and was directly associated with the infusion time of clinical grade WJMSCs. In addition, in vitro inhibitory antibody mediated blocking of sEV‐associated PD‐L1 restored T cell activation (TCA), suggesting a functional inhibitory role of sEVs‐PD‐L1. PD‐L1‐deficient sEVs isolated from WJMSCs following CRISPR‐Cas9 gene editing fail to inhibit TCA. Furthermore, we found that PD‐L1 is essential for WJMSC‐derived sEVs to modulate T cell receptors (TCRs). Our study reveals an important mechanism by which therapeutic WJMSCs modulate TCR‐mediated TCA through sEVs or sEV‐carried immune checkpoints. In addition, our clinical data suggest that sEV‐associated PD‐L1 may be not only useful in predicting the outcomes from WJMSC clinical administration, but also in developing cell‐independent therapy for aGvHD patients.

Melatonin activates ABCA1 via the BiP/NRF1 pathway to suppress high-cholesterol-induced apoptosis of mesenchymal stem cells

BACKGROUND

Retarded wound healing in patients with obesity contributes to a risk of complications associated with vascular insufficiency and oxidative stress. The high cholesterol levels of patients with obesity are associated with apoptosis of engrafted umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs). Melatonin contributes to the prevention of cholesterol accumulation in patients with obesity via a mechanism that is poorly understood. We therefore investigated the regulatory mechanism of melatonin in cholesterol-induced apoptosis.

METHODS

The protective effects of melatonin on cholesterol-induced apoptosis were investigated in UCB-MSCs. We used a mouse model of induced obesity to show that melatonin treatment restored the survival rate of transplanted UCB-MSCs and their wound-healing capacity. The mean values of the treatment groups were compared with those of the control group using Student's t test, and differences among three or more groups were analyzed using one-way analysis of variance with Dunnett's multiple comparison test.

RESULTS

Melatonin treatment increased the expression of ATP-binding cassette subfamily A member 1 (ABCA1), which reduced cholesterol accumulation and cholesterol-induced apoptosis. The mouse skin wound healing model showed that melatonin treatment restored the survival rate of transplanted UCB-MSCs and the wound-healing capacity of obese mice. Melatonin inhibited the expression of binding immunoglobulin protein (BiP) through the regulation of MT2/Sp1-dependent microRNA-597-5p. Melatonin decreased the co-localization of BiP with nuclear factor erythroid 2-related factor 1 (NRF1), which resulted in increased ABCA1 expression.

CONCLUSION

Melatonin induced the efflux of intracellular cholesterol through ABCA1 to decrease apoptosis of UCB-MSCs via an MT2-dependent BiP/NRF1 pathway.

Cell Sources for Human In vitro Bone Models

PURPOSE OF REVIEW

One aim in bone tissue engineering is to develop human cell-based, 3D in vitro bone models to study bone physiology and pathology. Due to the heterogeneity of cells among patients, patient's own cells are needed to be obtained, ideally, from one single cell source. This review attempts to identify the appropriate cell sources for development of such models.

RECENT FINDINGS

Bone marrow and peripheral blood are considered as suitable sources for extraction of osteoblast/osteocyte and osteoclast progenitor cells. Recent studies on these cell sources have shown no significant differences between isolated progenitor cells. However, various parameters such as medium composition affect the cell's proliferation and differentiation potential which could make the peripheral blood-derived stem cells superior to the ones from bone marrow. Peripheral blood can be considered a suitable source for osteoblast/osteocyte and osteoclast progenitor cells, being less invasive for the patient. However, more investigations are needed focusing on extraction and differentiation of both cell types from the same donor sample of peripheral blood.

[Regulatory effect of CCN3 on proliferation of mouse embryonic fibroblasts and its mechanism]

OBJECTIVE

To investigate the role of NOV/CCN3 in regulating the proliferation of mesenchymal stem cells (MSCs) and its regulatory mechanism and assess the value of CCN3 as a proliferative factor in bone tissue engineering.

METHODS

Mouse embryonic fibroblasts (MEFs) were used as the MSC model, in which CCN3 expression was up-regulated and downregulated by transfection with the recombinant adenovirus vectors Ad-CCN3 and Ad-siCCN3, respectively. Flow cytometry was used to analyze the changes in cell cycle and apoptosis of the transfected cells. Western blotting was used to detect the expression levels of the proliferation indicators (PCNA, cyclin E, and cyclin B1) and the apoptosis indicators (Bax and Bcl-2) to assess the effect of modulation of CCN3 expression on MEF proliferation and apoptosis. CCN3 protein secretion by the cells was detected using ELISA. RT-qPCR and Western blotting were employed to analyze the changes in the expressions of Notch1, ligand DLL1, the downstream key proteins or genes (Hey1, P300, H3K9) and MAPK pathway-related proteins ERK1+2 and p-ERK1+2.

RESULTS

Flow cytometry showed that compared with the control cells, MEFs transfected with Ad-CCN3 exhibited significantly increased cell proliferation index (P < 0.01) and lowered cell apoptosis rate (P < 0.05) with obviously enhanced expressions of PCNA, cyclin E and Bcl-2 proteins (P < 0.05). The results of RT-qPCR and Western blotting demonstrated that CCN3 overexpression significantly promoted the expression of Notch1 in the Notch signaling pathway (P < 0.001), inhibited the expressions of DLL1, Hey1, P300, and H3K9 (P < 0.05), and increased the protein expressions of ERK1+2 and P-ERk1+2 in the MAPK pathway (P < 0.01).

CONCLUSIONS

CCN3 over-expression promotes the proliferation and inhibits apoptosis of MEFs possibly by inhibiting the classical Notch signaling pathway and activating the MAPK pathway via binding to Notch1, suggesting the potential value of CCN3 as a proliferative factor of MSCs in bone tissue engineering.

Primary Cilia as a Biomarker in Mesenchymal Stem Cells Senescence: Influencing Osteoblastic Differentiation Potency Associated with Hedgehog Signaling Regulation

Bone tissue engineering-based therapy for bone lesions requires the expansion of seeding cells, such as autologous mesenchymal stem cells (MSCs). A major obstacle to this process is the loss of the phenotype and differentiation capacity of MSCs subjected to passage. Recent studies have suggested that primary cilia, primordial organelles that transduce multiple signals, particularly hedgehog signals, play a role in senescence. Therefore, we explored the relationships among senescence, primary cilia, and hedgehog signaling in MSCs. Ageing of MSCs by expansion in vitro was accompanied by increased cell doubling time. The osteogenic capacity of aged MSCs at passage 4 was compromised compared to that of primary cells. P4 MSCs exhibited reductions in the frequency and length of primary cilia associated with decreased intensity of Arl13b staining on cilia. Senescence also resulted in downregulation of the expression of hedgehog components and CDKN2A. Suppression of ciliogenesis reduced the gene expression of both Gli1, a key molecule in the hedgehog signaling pathway and ALP, a marker of osteoblastic differentiation. This study demonstrated that the senescence of MSCs induced the loss of osteoblastic differentiation potency and inactivated hedgehog signaling associated with attenuated ciliogenesis, indicating that primary cilia play a mediating role in and are biomarkers of MSC senescence; thus, future antisenescence strategies involving manipulation of primary cilia could be developed.

Adenine-Based Purines and Related Metabolizing Enzymes: Evidence for Their Impact on Tumor Extracellular Vesicle Activities

Extracellular vesicles (EVs), mainly classified as small and large EVs according to their size/origin, contribute as multi-signal messengers to intercellular communications in normal/pathological conditions. EVs are now recognized as critical players in cancer processes by promoting transformation, growth, invasion, and drug-resistance of tumor cells thanks to the release of molecules contained inside them (i.e., nucleic acids, lipids and proteins) into the tumor microenvironment (TME). Interestingly, secretion from donor cells and/or uptake of EVs/their content by recipient cells are regulated by extracellular signals present in TME. Among those able to modulate the EV-tumor crosstalk, purines, mainly the adenine-based ones, could be included. Indeed, TME is characterized by high levels of ATP/adenosine and by the presence of enzymes deputed to their turnover. Moreover, ATP/adenosine, interacting with their own receptors, can affect both host and tumor responses. However, studies on whether/how the purinergic system behaves as a modulator of EV biogenesis, release and functions in cancer are still poor. Thus, this review is aimed at collecting data so far obtained to stimulate further research in this regard. Hopefully, new findings on the impact of adenine purines/related enzymes on EV functions may be exploited in tumor management uncovering novel tumor biomarkers and/or druggable targets.

Delivery of miR-424-5p via Extracellular Vesicles Promotes the Apoptosis of MDA-MB-231 TNBC Cells in the Tumor Microenvironment

Programmed cell death ligand-1 (PD-L1) overexpressed on cancer cells has emerged as a key inhibitor that maintains the immunosuppressive microenvironment through its interaction with the PD-1 receptor in cancer. Here, we demonstrated that miR-424-5p delivery via extracellular vesicles (EVs) derived from adipose tissue-mesenchymal stromal cells (AT-MSCs) partly promotes proinflammation and enhances antitumor cytotoxicity in vitro and in vivo. Triple negative breast cancer (TNBC) exhibits increased expression of PD-L1, and PD-L1 is positively correlated with the overall survival of patients with TNBC. PD-L1 shows relatively higher expression in MDA-MB-231 (MM231) cells and can be downregulated by miR-424-5p. Furthermore, miR-424-5p transported by EVs can increase the secretion of proinflammatory cytokines, decrease the secretion of anti-inflammatory cytokines and promote the apoptosis of tumor cells. The intratumoral administration of miR-424-5p-EVs significantly slowed tumor growth. In conclusion, these results demonstrate that EVs may serve as a delivery system for novel immunotherapies for TNBC through the miR-424-5p/PD-L1 pathway.

Amniotic fluid-derived multipotent stromal cells drive diabetic wound healing through modulation of macrophages

Background

Cutaneous wounds in patients with diabetes exhibit impaired healing due to physiological impediments and conventional care options are severely limited. Multipotent stromal cells (MSCs) have been touted as a powerful new therapy for diabetic tissue repair owing to their trophic activity and low immunogenicity. However, variations in sources and access are limiting factors for broader adaptation and study of MSC-based therapies. Amniotic fluid presents a relatively unexplored source of MSCs and one with wide availability. Here, we investigate the potential of amniotic fluid-derived multipotent stromal cells (AFMSCs) to restore molecular integrity to diabetic wounds, amend pathology and promote wound healing.

Method

We obtained third trimester amniotic fluid from term cesarean delivery and isolated and expanded MSCs in vitro. We then generated 10 mm wounds in Lepr^db/db diabetic mouse skin, and splinted them open to allow for humanized wound modeling. Immediately after wounding, we applied AFMSCs topically to the sites of injuries on diabetic mice, while media application only, defined as vehicle, served as controls. Post-treatment, we compared healing time and molecular and cellular events of AFMSC-treated, vehicle-treated, untreated diabetic, and non-diabetic wounds. A priori statistical analyses measures determined significance of the data.

Result

Average time to wound closure was approximately 19 days in AFMSC-treated diabetic wounds. This was significantly lower than the vehicle-treated diabetic wounds, which required on average 27.5 days to heal (p < 0.01), and most similar to time of closure in wild type untreated wounds (an average of around 18 days). In addition, AFMSC treatment induced changes in the profiles of macrophage polarizing cytokines, resulting in a change in macrophage composition in the diabetic wound bed. We found no evidence of AFMSC engraftment or biotherapy induced immune response.

Conclusion

Treatment of diabetic wounds using amniotic fluid-derived MSCs encourages cutaneous tissue repair through affecting inflammatory cell behavior in the wound site. Since vehicle-treated diabetic wounds did not demonstrate accelerated healing, we determined that AFMSCs were therapeutic through their paracrine activities. Future studies should be aimed towards validating our observations through further examination of the paracrine potential of AFMSCs. In addition, investigations concerning safety and efficacy of this therapy in clinical trials should be pursued.

An Update on the Potential of Mesenchymal Stem Cell Therapy for Cutaneous Diseases

Mesenchymal stem or stromal cells (MSCs) are nonhematopoietic postnatal stem cells with self-renewal, multipotent differentiation, and potent immunomodulatory and anti-inflammatory capabilities, thus playing an important role in tissue repair and regeneration. Numerous clinical and preclinical studies have demonstrated the potential application of MSCs in the treatment of tissue inflammation and immune diseases, including inflammatory skin diseases. Therefore, understanding the biological and immunological characteristics of MSCs is important to standardize and optimize MSC-based regenerative therapy. In this review, we highlight the mechanisms underlying MSC-mediated immunomodulation and tissue repair/regeneration and present the latest development of MSC-based clinical trials on cutaneous diseases.

Preclinical Experimental Applications of miRNA Loaded BMSC Extracellular Vesicles

Bone marrow mesenchymal stem cells have been investigated for many years, especially for tissue regeneration, and have inherent limitations. One of the rapidly developing fields in the scientific world in recent years is extracellular vesicles. Especially, bone marrow mesenchymal stem cell originated extracellular vesicles are known to have positive contributions in tissue regeneration, and these extracellular vesicles have also been used as gene transfer systems for cellular therapy. Through gene expression analysis and bioinformatics tools, it is possible to determine which genes have changed in the targeted tissue or cell and which miRNAs that can correct this gene expression disorder. This approach connecting the stem cell, extracellular vesicles, epigenetics regulation and bioinformatics fields is one of the promising areas for the treatment of diseases in the future. With this review, it is aimed to present the studies carried out for the use of bone marrow stem cell-derived extracellular vesicles loaded with targeted miRNAs in different in vivo and in vitro human disease models and to discuss recent developments in this field.

Senescence-Associated Secretory Phenotype Suppression Mediated by Small-Sized Mesenchymal Stem Cells Delays Cellular Senescence through TLR2 and TLR5 Signaling

In order to provide a sufficient number of cells for clinical use, mesenchymal stem cells (MSCs) must be cultured for long-term expansion, which inevitably triggers cellular senescence. Although the small size of MSCs is known as a critical determinant of their fate, the main regulators of stem cell senescence and the underlying signaling have not been addressed. Umbilical cord blood-derived MSCs (UCB-MSCs) were obtained using size-isolation methods and then cultured with control or small cells to investigate the major factors that modulate MSC senescence. Cytokine array data suggested that the secretion of interukin-8 (IL-8) or growth-regulated oncogene-alpha (GROa) by senescent cells was markedly inhibited during incubation of small cells along with suppression of cognate receptor (C-X-C motif chemokine receptor2, CXCR2) via blockade of the autocrine/paracrine positive loop. Moreover, signaling via toll-like receptor 2 (TLR2) and TLR5, both pattern recognition receptors, drove cellular senescence of MSCs, but was inhibited in small cells. The activation of TLRs (2 and 5) through ligand treatment induced a senescent phenotype in small cells. Collectively, our data suggest that small cell from UCB-MSCs exhibit delayed cellular senescence by inhibiting the process of TLR signaling-mediated senescence-associated secretory phenotype (SASP) activation.

Investigation of the MSC Paracrine Effects on Alveolar-Capillary Barrier Integrity in the In Vitro Models of ARDS

Acute Respiratory Distress Syndrome (ARDS) is a devastating clinical disorder with high mortality rates and no specific pharmacological treatment available yet. It is characterized by excessive inflammation in the alveolar compartment resulting in edema of the airspaces due to loss of integrity in the alveolar epithelial-endothelial barrier leading to the development of hypoxemia and often severe respiratory failure. Changes in the permeability of the alveolar epithelial-endothelial barrier contribute to excessive inflammation, the formation of lung edema and impairment of the alveolar fluid clearance. In recent years, Mesenchymal Stromal Cells (MSCs) have attracted attention as a cell therapy for ARDS. MSCs are known to secrete a variety of biologically active factors (growth factors, cytokines, and extracellular vesicles). These paracrine factors have been shown to be major effectors of the anti-inflammatory and regenerative properties observed in multiple in vitro and in vivo studies. This chapter provides a simple protocol on how to investigate the paracrine effect of MSCs on the alveolar epithelial-endothelial barrier functions.

Circular RNA circ_0011269 sponges miR-122 to regulate RUNX2 expression and promotes osteoporosis progression

Circular RNAs (circRNAs) are a novel class of noncoding RNAs that are widely expressed in human disease. However, circRNAs expression profile and potential mechanism in osteoporosis pathogenesis remain to be further studied. In the present study, a total of 69 circRNAs were identified to be abnormally expressed in osteoporosis patient samples by microarray and bioinformatics analyses. We found that circ_0011269 was notably downregulated in osteoporosis (fold change, 3.94). By means of miRanda algorithm, we constructed the interaction network of circ_0011269-miRNAs in osteoporosis based on target binding and miR-122 was enrolled in the network. Dual-luciferase reporter assay verified the target relationship of miR-122 and circ_0011269/RUNX2. The expression of circ_0011269 and RUNX2 were gradually increased during osteogenic differentiation while miR-122 exhibited a decreased expression. Moreover, overexpression of circ_0011269 could promote RUNX2 expression and inhibit osteoporosis. In summary, this study found that circ_0011269 sponges miR-122 to regulate RUNX2 expression and promotes osteoporosis progression.

The Impact of Advanced Glycation End-Products (AGEs) on Proliferation and Apoptosis of Primary Stem Cells: A Systematic Review

Stem cell-based regenerative therapies hold great promises to treat a wide spectrum of diseases. However, stem cell engraftment and survival are still challenging due to an unfavorable transplantation environment. Advanced glycation end-products (AGEs) can contribute to the generation of these harmful conditions. AGEs are a heterogeneous group of glycated products, nonenzymatically formed when proteins and/or lipids become glycated and oxidized. Our typical Western diet as well as cigarettes contain high AGEs content. AGEs are also endogenously formed in our body and accumulate with senescence and in pathological situations. Whether AGEs have an impact on stem cell viability in regenerative medicine remains unclear, and research on the effect of AGEs on stem cell proliferation and apoptosis is still ongoing. Therefore, this systematic review provides a clear overview of the effects of glycated proteins on cell viability in various types of primary isolated stem cells used in regenerative medicine.

GPR173 agonist phoenixin 20 promotes osteoblastic differentiation of MC3T3-E1 cells

Osteogenic differentiation is critical to bone homeostasis, and its imbalance plays a key role in the progression of osteoporosis. Osteoblast cells are responsible for synthesizing new bone tissue, and understanding how to control osteoblastic differentiation is vital to the treatment of osteoporosis. Herein, we show that GPR173 signaling is involved in the regulation of osteoblastic differentiation in MC3T3-E1 cells. Our data reveals that GPR173 is abundantly expressed in MC3T3-E1 cells, and its expression is inducible upon the introduction of osteogenic media. The activation of GPR173 by its selective agonist phoenixin 20 induces the expression of several osteoblast signature genes including collagen type 1 alpha 1 (Col-I), osteocalcin (OCN), alkaline phosphatase (ALP) as well as increased matrix mineralization and ALP activity, suggesting that the activation of GPR173 promotes osteoblastic differentiation. Moreover, we show that the effect of phoenixin 20 is mediated by its induction on the key regulator runt-Related Transcription Factor 2 (Runx2). Mechanistically, we display that the action of phoenixin 20 requires the activation of MAPK kinase p38, and deactivation of p38 by its inhibitor SB203580 weakens the phoenixin 20-mediated induction of RUNX-2, ALP, and matrix mineralization. Silencing of GPR173 attenuates phoenixin 20-mediated osteoblastic differentiation, indicating its dependence on the receptor. Collectively, our study reveals a new role of GPR173 and its agonist phoenixin 20 in osteoblastic differentiation.

Human mesenchymal stem cells treatment improved hepatic lesions and reversed gut microbiome disorder in non-alcoholic steatohepatitis

Effective therapies for non-alcoholic steatohepatitis (NASH) are urgently needed. We investigated the effect of human mesenchymal stem cells (hMSCs) on the intestinal flora in NASH treatment. We isolated the hMSCs from the umbilical cords and divided male C57BL/6 mice into three groups, namely, chow, methionine-choline-deficient (MCD), and MCD+hMSCs. After collecting the feces and liver of the mice, we evaluated the histological changes in the liver and measured the inflammatory and fibrogenesis cytokines. Fecal microbiome and metabolome were analyzed using 16S rRNA gene sequencing analyses. The hMSCs treatment could alleviate hepatic steatosis, inflammation and fibrosis induced by MCD diet. It could also reverse the microbiome and metabolome disorders in the NASH model. Correlation analysis of the interaction among bacteria amplified the effects of the bacteria in host. In conclusion, hMSCs treatment could improve NASH-related lesions and reverse gut microbiome and metabolome disorder in NASH.

Establishment of human immortalized mesenchymal stem cells lines for the monitoring and analysis of osteogenic differentiation in living cells

Mesenchymal stem cells (MSCs) are expected to be useful in bone regeneration treatment for various diseases and conditions, including cleft lip and palate, fracture, and bone absorption. However, to date, MSCs have failed to produce satisfactory results in clinical settings. This is primarily due to the low rate of induced osteogenic differentiation. To realize MSC potential, it is necessary to establish methods for the isolation of MSC-derived living osteoblasts. However, no osteoblast markers have been reported to date. In an attempt to develop a method for the assessment of osteoblast differentiation, we established reporter human immortalized MSC (hiMSC) lines for in vitro monitoring of bone gamma-carboxyglutamate protein (BGLAP, osteocalcin) expression. To this end, we successfully knocked-in an enhanced green fluorescent protein (EGFP) gene cassette immediately downstream of the first ATG of BGLAP via CRISPR-Cas9, and established hiMSC lines expressing EGFP to monitor osteogenic differentiation. On differentiation day 7, EGFP-positive cells were collected by flow cytometric cell sorting, and the expression of EGFP and endogenous BGLAP was analyzed. During osteogenic differentiation, EGFP upregulation was found to correlate with expression of endogenous BGLAP. Moreover, mineralization was confirmed using Alizarin red-S staining after two weeks of osteogenic differentiation of the modified hiMSC lines. The modified hiMSC lines, as well as the derived differentiated osteoblasts obtained herein, are valuable tools for the monitoring osteoblast gene and protein expression, and can be used to develop novel methods for isolating living osteoblasts.

Regenerative medicine approaches for the management of respiratory tract fistulas

Respiratory tract fistulas (or fistulae) are abnormal communications between the respiratory system and the digestive tract or the adjacent organs. The origin can be congenital or, more frequently, iatrogenic and the clinical presentation is heterogeneous. Respiratory tract fistulas can lead to severely reduced health-related quality of life and short survival. Therapy mainly relies on endoscopic surgical interventions but patients often require prolonged hospitalization and may develop complications. Therefore, more conservative regenerative medicine approaches, mainly based on lipotransfer, have also been investigated. Adipose tissue can be delivered either as unprocessed tissue, or after enzymatic treatment to derive the cellular stromal vascular fraction. In the current narrative review, we provide an overview of the main tissue/cell-based clinical studies for the management of various types of respiratory tract fistulas or injuries. Clinical experience is limited, as most of the studies were performed on a small number of patients. Albeit a conclusive proof of efficacy cannot be drawn, the reviewed studies suggest that grafting of adipose tissue-derived material may represent a minimally invasive and conservative treatment option, alternative to more aggressive surgical procedures. Knowledge on safety and tolerability acquired in prior studies can lead to the design of future, larger trials that may exploit innovative procedures for tissue processing to further improve the clinical outcome.

Generation of Insulin-Producing Cells from Canine Adipose Tissue-Derived Mesenchymal Stem Cells

The potential of mesenchymal stem cells (MSCs) to differentiate into nonmesodermal cells such as pancreatic beta cells has been reported. New cell-based therapy using MSCs for diabetes mellitus is anticipated as an alternative treatment option to insulin injection or islet transplantation in both human and veterinary medicine. Several protocols were reported for differentiation of MSCs into insulin-producing cells (IPCs), but no studies have reported IPCs generated from canine MSCs. The purpose of this study was to generate IPCs from canine adipose tissue-derived MSCs (AT-MSCs) in vitro and to investigate the effects of IPC transplantation on diabetic mice in vivo. Culturing AT-MSCs with the differentiation protocol under a two-dimensional culture system did not produce IPCs. However, spheroid-like small clusters consisting of canine AT-MSCs and human recombinant peptide μ-pieces developed under a three-dimensional (3D) culture system were successfully differentiated into IPCs. The generated IPCs under 3D culture condition were stained with dithizone and anti-insulin antibody. Canine IPCs also showed gene expression typical for pancreatic beta cells and increased insulin secretion in response to glucose stimulation. The blood glucose levels in streptozotocin-induced diabetic mice were decreased after injection with the supernatant of canine IPCs, but the hyperglycemic states of diabetic mice were not improved after transplanting IPCs subcutaneously or intramesenterically. The histological examination showed that the transplanted small clusters of IPCs were successfully engrafted to the mice and included cells positive for insulin by immunofluorescence. Several factors, such as the transplanted cell number, the origin of AT-MSCs, and the differentiation protocol, were considered potential reasons for the inability to improve the hyperglycemic state after IPC transplantation. These findings suggest that canine AT-MSCs can be differentiated into IPCs under a 3D culture system and IPC transplantation may be a new treatment option for dogs with diabetes mellitus.

Analysis of cell-biomaterial interaction through cellular bridge formation in the interface between hGMSCs and CaP bioceramics

The combination of biomaterials and stem cells for clinical applications constitute a great challenge in bone tissue engineering. Hence, cellular networks derived from cells-biomaterials crosstalk have a profound influence on cell behaviour and communication, preceding proliferation and differentiation. The purpose of this study was to investigate in vitro cellular networks derived from human gingival mesenchymal stem cells (hGMSCs) and calcium phosphate (CaP) bioceramic interaction. Biological performance of CaP bioceramic and hGMSCs interaction was evaluated through cell adhesion and distribution, cellular proliferation, and potential osteogenic differentiation, at three different times: 5 h, 1 week and 4 weeks. Results confirmed that hGMSCs met the required MSCs criteria while displaying osteogenic differentiaton capacities. We found a significant increase of cellular numbers and proliferation levels. Also, protein and mRNA OPN expression were upregulated in cells cultured with CaP bioceramic by day 21, suggesting an osteoinductible effect of the CaP bioceramic on hGMSCs. Remarkably, CaP bioceramic aggregations were obtained through hGMSCs bridges, suggesting the in vitro potential of macrostructures formation. We conclude that hGMSCs and CaP bioceramics with micro and macropores support hGMSC adhesion, proliferation and osteogenic differentiation. Our results suggest that investigations focused on the interface cells-biomaterials are essential for bone tissue regenerative therapies.

Identifying Barriers to Umbilical Cord Blood Banking in Jordan: A Cross-Sectional Survey of Obstetricians

Background: The expansion of umbilical cord blood (UCB) banking necessitates a greater understanding among obstetricians in order to responsibly inform parents about UCB collection and storage. Gaps in knowledge can compromise public UCB banking efforts and result in missed opportunities and public misguidance about UCB banking. Materials and Methods: A cross-sectional survey was disseminated among obstetricians in Amman, Jordan. The questionnaire aimed to evaluate obstetricians' knowledge of and attitude toward UCB storage and applications, as well as current practice patterns. Results: Ninety-six obstetricians responded (55% response rate), most of whom were Jordanian (71%), female (83%), resident physicians (59%), and working in either private (43%) or public (42%) hospitals, with an average of 6.5 years in practice. Only 26% had personal experience in UCB collection, and 20% had received education on UCB collection. Nearly 75% said their hospitals lacked standard operating procedures, guidelines, or infectious disease screening for UCB units. Overall knowledge about UCB was moderate, and the internet was the most common information source (54%). Overall attitudes were positive, especially in desire to expand personal knowledge about UCB, integrate information into medical residency curricula, and establish a public UCB bank in Jordan. However, many believed that ethical (61%) and religious (56%) controversies surround UCB donation. Conclusion: This study identifies deficiencies in quality control and experience in UCB collection in Jordan, as well as areas of inadequate knowledge and ethical controversies among obstetricians. These issues contribute to public misinformation and limit public UCB donation programs, and requires improved medical education on this topic.

Stem Cell-Based Disease Modeling and Cell Therapy

Stem cell science is among the fastest moving fields in biology, with many highly promising directions for translatability. To centralize and contextualize some of the latest developments, this Special Issue presents state-of-the-art research of adult stem cells, induced pluripotent stem cells (iPSCs), and embryonic stem cells as well as cancer stem cells. The studies we include describe efficient differentiation protocols of generation of chondrocytes, adipocytes, and neurons, maturation of iPSC-derived cardiomyocytes and neurons, dynamic characterization of iPSC-derived 3D cerebral organoids, CRISPR/Cas9 genome editing, and non-viral minicircle vector-based gene modification of stem cells. Different applications of stem cells in disease modeling are described as well. This volume also highlights the most recent developments and applications of stem cells in basic science research and disease treatments.

Production of Baculovirus and Stem Cells for Baculovirus-Mediated Gene Transfer into Human Mesenchymal Stem Cells

The discovery of the genome-editing tool CRISPR-Cas9 is revolutionizing the world of gene therapy and will extend the gene therapy product pipeline. While applying gene therapy products, the main difficulty is an efficient and effective transfer of the nucleic acids carrying the relevant information to their target destination, the nucleus of the cells. Baculoviruses have shown to be very suitable transport vehicles for this task due to, inter alia, their ability to transduce mammalian/human cells without being pathogenic. This property allows the usage of baculovirus-transduced cells as cell therapy products, thus, combining the advantages of gene and cell therapy. To make such pharmaceuticals available for patients, a successful production and purification is necessary. In this chapter, we describe the generation of a pseudotyped baculovirus vector, followed by downstream processing using depth and tangential-flow filtration. This vector is used subsequently to transduce human mesenchymal stem cells. The production of the cells and the subsequent transduction process are illustrated.

Bioengineering strategies for the treatment of peripheral arterial disease

Peripheral arterial disease (PAD) is a progressive atherosclerotic disorder characterized by narrowing and occlusion of arteries supplying the lower extremities. Approximately 200 million people worldwide are affected by PAD. The current standard of operative care is open or endovascular revascularization in which blood flow restoration is the goal. However, many patients are not appropriate candidates for these treatments and are subject to continuous ischemia of their lower limbs. Current research in the therapy of PAD involves developing modalities that induce angiogenesis, but the results of simple cell transplantation or growth factor delivery have been found to be relatively poor mainly due to difficulties in stem cell retention and survival and rapid diffusion and enzymolysis of growth factors following injection of these agents in the affected tissues. Biomaterials, including hydrogels, have the capability to protect stem cells during injection and to support cell survival. Hydrogels can also provide a sustained release of growth factors at the injection site. This review will focus on biomaterial systems currently being investigated as carriers for cell and growth factor delivery, and will also discuss biomaterials as a potential stand-alone method for the treatment of PAD. Finally, the challenges of development and use of biomaterials systems for PAD treatment will be reviewed.

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Biomaterial systems investigated as carriers for cell and growth factor delivery for PAD are overviewed.

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Biomaterials as a potential stand-alone method for the treatment of PAD are discussed.

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The challenges of development and use of biomaterials systems for PAD treatment are commented.

Mesenchymal Stem Cell Therapy and Alzheimer's Disease: Current Status and Future Perspectives

Alzheimer's disease (AD) is the most common progressive neurodegenerative disease worldwide, but its cause remains unclear. Although a few drugs can provide temporary and partial relief of symptoms in some patients, no curative treatment is available. Therefore, attention has been focused on research using stem cells to treat AD. Among stem cells, mesenchymal stem cells (MSCs) have been used to treat the related pathologies in animal models of AD, and other neurodegenerative disease. This review describes latest research trends on the use of MSC-based therapies in AD and its action of mechanism. MSCs have several beneficial effects. They would be specified as the reduction of neuroinflammation, the elimination of amyloid-β, neurofibrillary tangles, and abnormal protein degradation, the promotion of autophagy-associated and blood-brain barrier recoveries, the upregulation of acetylcholine levels, improved cognition, and the recovery of mitochondrial transport. Therefore, this review describes the latest research trends in MSC-based therapy for AD by demonstrating the importance of MSC-based therapy and understanding of its mechanisms in AD and discusses the limitations and perspectives of stem cell therapy in AD.

β-mercaptoethanol promotes osteogenesis of human mesenchymal stem cells via sirt1-ERK pathway

Human umbilical cord-derived mesenchymal stem cells (hUMSCs) hold strong self-renewal capacity and low immunogenicity, which have attracted attention as potential candidates for bone repair and regeneration. However, insufficient osteogenic differentiation markedly hinders the clinical applications of hUMSCs. In the present study, the effect of β-mercaptoethanol (BME), a small molecule antioxidant which has been identified to regulate cell proliferation and differentiation, on osteogenic differentiation of hUMSCs and underlying signaling mechanism were investigated. The results indicated that under osteogenic induction conditions, BME treatment increased the alkaline phosphatase (ALP) activity and promoted calcium mineralization in hUMSCs. The gene and protein expression of osteogenesis-related markers such as ALP, osteopontin (OPN), osteocalcin (OCN) and collagen type I (COLI) were also significantly up-regulated. Besides, BME promoted the protein expression of silent information regulator type 1 (sirt1) and stimulated the activation of extracellular signal-related kinase (ERK), contributing to increased Runx2 expression. Furthermore, blocking the expression of sirt1 attenuated BME-enhanced ERK phosphorylation and osteogenic differentiation of hUMSCs. These results indicated that BME accelerated osteogenic differentiation of hUMSCs by activating the sirt1-ERK signaling pathway, thereby providing insights into the development of MSCs-based bone regeneration strategies.

MiR-920 promotes osteogenic differentiation of human bone mesenchymal stem cells by targeting HOXA7

Background

To explore the effect of miR-920 on osteogenic differentiation of human bone mesenchymal stem cells (hBMSCs) and the possible mechanism.

Methods

Osteoporosis (OP) and healthy control bone tissues were collected, and the relative expression of miR-920 and HOXA7 was measured. hBMSCs were isolated and cultured in vitro. Alkaline phosphatase activity and miR-920 and HOXA7 relative expression were measured during osteogenic differentiation of hBMSCs. Then, bioinformatic analysis was performed to assess the potential mechanism of miR-920. MiR-920 mimic and inhibitor were introduced into hBMSCs by lipofection transfection and were used to investigate the effect of miR-920 on the osteogenic differentiation of hBMSCs. A dual luciferase reporter assay was used to identify whether the 3′UTR of HOXA7 mRNA was a direct target of miR-920. Western blotting was performed to assess whether miR-920 affected the MAPK signaling pathway.

Results

We found that miR-920 was downregulated in OP patients compared with controls, while HOXA7 was upregulated, and miR-920 had a negative correlation with HOXA7 (r = − 0.859, P = 0.001). Moreover, miR-920 was increased during osteogenic differentiation of hBMSCs, while HOXA7 had the opposite tendency. Bioinformatic analysis revealed that there were a total of 207 target genes, and MAPK was a potential targeted signaling pathway. MiR-920 mimic significantly increased ALP activity, calcium deposition, osteoblastic protein expression (ALP and OSX), and p-p38 and p-JNK protein levels.

Conclusion

Overall, miR-920 promotes osteogenic differentiation of hBMSCs by targeting HOXA7 through the MAPK signaling pathway.

Inhibition of miR-34a reduces cellular senescence in human adipose tissue-derived mesenchymal stem cells through the activation of SIRT1

AIMS

Human adipose derived mesenchymal stem cells (hAD-MSCs) as the most promising target for cell therapy and regenerative medicine, face senescence as a major drawback resulting in their limited proliferation and differentiation potentials. To evaluate the efficacy of miR-34a silencing as an anti-senescence strategy in hAD-MSCs, in this study common hallmarks of senescence were assessed after transient inhibition of miR-34a in hAD-MSCs.

MATERIALS AND METHODS

The expression levels of miR-34a in hAD-MSCs at different passages were evaluated by real-time quantitative PCR. hAD-MSCs at passage 2 and passage 7 were transfected with miR-34a inhibitor. Doubling time assay, colony forming assay, and cell cycle analysis were performed to evaluate cell proliferation rate. The activity of senescence associated β-galactosidase (SA-β-gal) was assessed by histochemical staining. Moreover, the senescence associated molecular alterations including that of pro-senescence (P53, P21 and P16) and anti-senescence (SIRT1, HTERT and CD44) genes were examined by quantitative RT-PCR and western blot assays. To evaluate the differentiation potentials of MSCs, following adipogenic and osteogenic induction, the expression levels of lineage specific markers were analyzed by qPCR.

KEY FINDINGS

Our results showed that inhibition of miR-34a enhances the proliferation, promotes the adipogenic and osteogenic differentiation potency, reduces the senescence associated-β gal activity, and reverses the senescence associated molecular alterations in hAD-MSCs.

SIGNIFICANCE

In this study, we showed that inhibition of miR-34a reduces the cellular senescence through the activation of SIRT1. Our findings support the silencing of miR-34a as an anti-senescence approach to improve the therapeutic potentials of hAD-MSCs.

Mesenchymal stromal cells and their secreted extracellular vesicles as therapeutic tools for COVID-19 pneumonia?

The COVID-19 epidemic represents an unprecedented global health emergency, further aggravated by the lack of effective therapies. For this reason, several clinical trials are testing different off-label drugs, already approved for other pathologies. Mesenchymal stem/stromal cells (MSCs) have been tested during the last two decades for the treatment of various pathologic conditions, including acute and chronic lung diseases, both in animal models and in patients. In particular, promising results have been obtained in the experimental therapy of acute respiratory distress syndrome, which represents the most threatening complication of COVID-19 infection. Furthermore, more recently, great interest has been devoted to the possible clinical applications of extracellular vesicles secreted by MSCs, nanoparticles that convey much of the biological effects and of the therapeutic efficacy of their cells of origin. This review summarizes the experimental evidence underlying the possible use of MSCs and of MSC-EVs in severe COVID-19 infection and underlines the need to evaluate the possible efficacy of these therapeutic approaches through controlled studies under the supervision of the Regulatory Authorities.

Stem cell therapy for COVID-19 and other respiratory diseases: Global trends of clinical trials

Respiratory diseases, including coronavirus disease 2019 and chronic obstructive pulmonary disease (COPD), are leading causes of global fatality. There are no effective and curative treatments, but supportive care only. Cell therapy is a promising therapeutic strategy for refractory and unmanageable pulmonary illnesses, as proved by accumulating preclinical studies. Stem cells consist of totipotent, pluripotent, multipotent, and unipotent cells with the potential to differentiate into cell types requested for repair. Mesenchymal stromal cells, endothelial progenitor cells, peripheral blood stem cells, and lung progenitor cells have been applied to clinical trials. To date, the safety and feasibility of stem cell and extracellular vesicles administration have been confirmed by numerous phase I/II trials in patients with COPD, acute respiratory distress syndrome, bronchial dysplasia, idiopathic pulmonary fibrosis, pulmonary artery hypertension, and silicosis. Five routes and a series of doses have been tested for tolerance and advantages of different regimes. In this review, we systematically summarize the global trends for the cell therapy of common airway and lung diseases registered for clinical trials. The future directions for both new clinical trials and preclinical studies are discussed.

Tumor cells derived-exosomes as angiogenenic agents: possible therapeutic implications

Angiogenesis is a multistep process and various molecules are involved in regulating it. Extracellular vesicles are cell-derived particles, secreted from several types of cells and are known to mediate cell-to-cell communication. These vesicles contain different bio-molecules including nucleic acids, proteins, and lipids, which are transported between cells and regulate physiological and pathological conditions in the recipient cell. Exosomes, 30–150 nm extracellular vesicles, and their key roles in tumorigenesis via promoting angiogenesis are of great recent interest. In solid tumors, the suitable blood supply is the hallmark of their progression, growth, and metastasis, so it can be supported by angiogenesis. Tumor cells abundantly release exosomes containing different kinds of biomolecules such as angiogenic molecules that contribute to inducing angiogenesis. These exosomes can be trafficked between tumor cells or between tumor cells and endothelial cells. The protein and nucleic acid cargo of tumor derived-exosomes can deliver to endothelial cells mostly by endocytosis, and then induce angiogenesis. Tumor derived-exosomes can be used as biomarker for cancer diagnosis. Targeting exosome-induced angiogenesis may serve as a promising tool for cancer therapy. Taken together, tumor derived-exosomes are the major contributors in tumor angiogenesis and a supposed target for antiangiogenic therapies. However, further scrutiny is essential to investigate the function of exosomes in tumor angiogenesis and clinical relevance of targeting exosomes for suppressing angiogenesis.

Molecular and Functional Phenotypes of Human Bone Marrow-Derived Mesenchymal Stromal Cells Depend on Harvesting Techniques

Mesenchymal stromal cells (MSC) harvested in different tissues from the same donor exhibit different phenotypes. Each phenotype is not only characterized by a certain pattern of cell surface markers, but also different cellular functionalities. Only recently were different harvesting and processing techniques found to contribute to this phenomenon as well. This study was therefore set up to investigate proteomic and functional properties of human bone marrow-derived MSCs (hBM-MSC). These were taken from the same tissue and donor site but harvested either as aspirate or bone chip cultures. Both MSC populations were profiled for MSC markers defined by the International Society for Cellular Therapy (ISCT), MSC markers currently under discussion and markers of particular interest. While classic ISCT MSC markers did not show any significant difference between aspirate and outgrowth hBM-MSCs, our additional characterization panel revealed distinct patterns of differentially expressed markers. Furthermore, hBM-MSCs from aspirate cultures demonstrated a significantly higher osteogenic differentiation potential than outgrowth MSCs, which could be confirmed using a transcriptional approach. Our comparison of MSC phenotypes obtained by different harvesting techniques suggests the need of future standardized harvesting, processing and phenotyping procedures in order to gain better comparability in the MSC field.

Regenerative potential of Wharton's jelly-derived mesenchymal stem cells: A new horizon of stem cell therapy

Umbilical cord Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) have recently gained considerable attention in the field of regenerative medicine. Their high proliferation rate, differentiation ability into various cell lineages, easy collection procedure, immuno-privileged status, nontumorigenic properties along with minor ethical issues make them an ideal approach for tissue repair. Besides, the number of WJ-MSCs in the umbilical cord samples is high as compared to other sources. Because of these properties, WJ-MSCs have rapidly advanced into clinical trials for the treatment of a wide range of disorders. Therefore, this paper summarized the current preclinical and clinical studies performed to investigate the regenerative potential of WJ-MSCs in neural, myocardial, skin, liver, kidney, cartilage, bone, muscle, and other tissue injuries.

The cytotoxicity of advanced glycation end products was attenuated by UCMSCs in human vaginal wall fibroblasts by inhibition of an inflammatory response and activation of PI3K/AKT/PTEN

Pelvic organ prolapse (POP) occurs when the pelvic organs (bladder, bowel or uterus) herniate into the vagina, causing incontinence, voiding, and bowel and sexual dysfunction, negatively impacting upon a woman's quality of life. Intermediate intermolecular cross-links and advanced glycation cross-links increase in prolapsed tissue. Stem cells are able to participate in tissue repair due to their ability to differentiate into multiple lineages, and thus into various types of connective tissue cells, so they therefore hold great promise for treating pelvic floor dysfunction. The current study found that advanced glycation end products (AGEs) inhibited the viability and proliferation of human vaginal wall fibroblasts (VWFs), were cytotoxic to VWFs, and also induced the apoptosis of VWFs. In contrast, umbilical cord-derived mesenchymal stem cells (UCMSCs) secreted anti-inflammation cytokines to protect against the cytotoxic effects of fibroblasts induced by AGEs and attenuated the cytotoxic effect of AGE on fibroblasts by activation of the PI3K/Akt-PTEN pathway. This study demonstrated that UCMSCs inhibited the cytotoxic effect of AGE in cells from patients with POP by inducing an anti-inflammatory reaction and activating the PI3K/AKT/PTEN signaling pathway. The current results provide important insights into use of stem cells to treat POP.

Transplantation of human dental pulp stem cells in streptozotocin-induced diabetic rats

Type 1 diabetes mellitus (T1DM) is a chronic metabolic disease caused by the destruction of pancreatic β-cells. Human dental pulp stem cells represent a promising source for cell-based therapies, owing to their easy, minimally invasive surgical access, and high proliferative capacity. It was reported that human dental pulp stem cells can differentiate into a pancreatic cell lineage in vitro; however, few studies have investigated their effects on diabetes. Our study aimed to investigate the therapeutic potential of intravenous and intrapancreatic transplantation of human dental pulp stem cells in a rat model of streptozotocin-induced type 1 diabetes. Forty Sprague Dawley male rats were randomly categorized into four groups: control, diabetic (STZ), intravenous treatment group (IV), and intrapancreatic treatment group (IP). Human dental pulp stem cells (1 × 10⁶ cells) or vehicle were injected into the pancreas or tail vein 7 days after streptozotocin injection. Fasting blood glucose levels were monitored weekly. Glucose tolerance test, rat and human serum insulin and C-peptide, pancreas histology, and caspase-3, vascular endothelial growth factor, and Ki67 expression in pancreatic tissues were assessed 28 days post-transplantation. We found that both IV and IP transplantation of human dental pulp stem cells reduced blood glucose and increased levels of rat and human serum insulin and C-peptide. The cells engrafted and survived in the streptozotocin-injured pancreas. Islet-like clusters and scattered human dental pulp stem cells expressing insulin were observed in the pancreas of diabetic rats with some difference in the distribution pattern between the two injection routes. RT-PCR analyses revealed the expression of the human-specific pancreatic β-cell genes neurogenin 3 (NGN3), paired box 4 (PAX4), glucose transporter 2 (GLUT2), and insulin in the pancreatic tissues of both the IP and IV groups. In addition, the transplanted cells downregulated the expression of caspase-3 and upregulated the expression of vascular endothelial growth factor and Ki67, suggesting that the injected cells exerted pro-angiogenetic and antiapoptotic effects, and promoted endogenous β-cell replication. Our study is the first to show that human dental pulp stem cells can migrate and survive within streptozotocin-injured pancreas, and induce antidiabetic effects through the differentiation and replacement of lost β-cells and paracrine-mediated pancreatic regeneration. Thus, human dental pulp stem cells may have therapeutic potential to treat patients with long term T1DM.

Extracellular vesicles derived from human ES-MSCs protect retinal ganglion cells and preserve retinal function in a rodent model of optic nerve injury

Background

Retinal and/or optic nerve injury is one of the leading causes of blindness due to retinal ganglion cell (RGC) degeneration. There have been extensive efforts to suppress this neurodegeneration. Various somatic tissue-derived mesenchymal stem cells (MSCs) demonstrated significant neuroprotective and axogenic effects on RGCs. An alternative source of MSCs could be human embryonic stem cells (ES-MSCs), which proliferate faster, express lower levels of inflammatory cytokines, and are capable of immune modulation. It has been demonstrated that MSCs secrete factors or extracellular vesicles that may heal the injury. However, possible therapeutic effects and underlying mechanism of human ES-MSC extracellular vesicles (EVs) on optic nerve injury have not been assessed.

Methods

EVs were isolated from human ES-MSCs. Then, ES-MSC EV was applied to an optic nerve crush (ONC) mouse model. Immunohistofluorescence, retro- and anterograde tracing of RGCs, Western blot, tauopathy in RGCs, and function assessments were performed during 2-month post-treatment to evaluate ONC improvement and underlying mechanism of human ES-MSC EV in in vivo.

Results

We found that the ES-MSC EV significantly improved Brn3a+ RGCs survival and retro- and anterograde tracing of RGCs, while preventing retinal nerve fiber layer (RNFL) degenerative thinning compared to the vehicle group. The EVs also significantly promoted GAP43+ axon counts in the optic nerve and improved cognitive visual behavior. Furthermore, cis p-tau, a central mediator of neurodegeneration in the injured RGCs, is detectable after the ONC at the early stages demonstrated tauopathy in RGCs. Notably, after EV treatment cis p-tau was downregulated.

Conclusions

Our findings propose that human ES-MSC EVs, as an off-the-shelf and cell-free product, may have profound clinical implications in treating injured RGCs and degenerative ocular disease. Moreover, the possible mechanisms of human ES-MSC EV are related to the rescue of tauopathy process of RGC degeneration.