Umbilical cord as a long-term source of activatable mesenchymal stromal cells for immunomodulation

Immunomodulatory potential of cytokine-licensed human bone marrow-derived mesenchymal stromal cells correlates with potency marker expression profile

Cytokine(s) pre-activation/licensing is an effective way to enhance the immunomodulatory potency of mesenchymal stromal cells (MSCs). Currently, IFN-γ licensing received the most attention in comparison with other cytokines. After licensing human bone marrow-derived MSCs with pro-/anti-inflammatory cytokines IFN-γ, IL-1β, TNF-α, TGF-β1 alone or in combination, the in vitro immunomodulatory potency of these MSCs was studied by incubating with allogeneic T cells and macrophage-like THP-1 cells. In addition, immunomodulation-related molecules filtered by bioinformatics, complement 1 subcomponent (C1s), and interferon-induced GTP-binding protein Mx2 (MX2), were studied to verify whether to reflect the immunomodulatory potency. Herein, we reported that different cytokines cause different effects on the function of MSC. While TGF-β1 licensing enhances the capacity of MSCs to induce T cells with an immunosuppressive phenotype, IFN-γ-licensing strengthens the inhibitory effect of MSC on T cell proliferation. Both TGF-β1 and IFN-γ licensing can enhance the effect of MSC on reducing the expression of pro-inflammatory cytokines by M1 macrophage-like THP-1 cells. Interestingly, IFN-γ upregulates potential potency markers extracellular C1s and kynurenine (KYN) and intracellular MX2. These 3 molecules have the potential to reflect mesenchymal stromal cell immunomodulatory potency. In addition, we reported that there is a synergistic effect of TGF-β1 and IFN-γ in immunomodulation.

Safety and efficacy of umbilical cord tissue-derived mesenchymal stem cells in the treatment of patients with aging frailty: a phase I/II randomized, double-blind, placebo-controlled study

BACKGROUND

Mesenchymal stem cells (MSCs) hold a great promise for cell-based therapy in the field of regenerative medicine. In this study, we aimed to evaluate the safety and efficacy of intravenous infusion of human umbilical cord-derived MSCs (HUC-MSCs) in patients with aging frailty.

METHODS

In this randomized, double-blind, placebo-controlled trial, participants diagnosed with aging frailty were randomly assigned to receive intravenous administrations of HUC-MSCs or placebo. All of serious adverse events and AEs were monitored to evaluate the safety of treatment during the 6-month follow-up. The primary efficacy endpoint was alteration of physical component scores (PCS) of SF-36 qualities of life at 6 months. The secondary outcomes including physical performance tests and pro-inflammatory cytokines, were also observed and compared at each follow-up visits. All evaluations were performed at 1 week, 1, 2, 3 and 6 months following the first intravenous infusion of HUC-MSCs.

RESULTS

In the MSCs group, significant improvements in PCS of SF-36 were observed from first post-treatment visit and sustained throughout the follow-up period, with greater changes compared to the placebo group (p = 0.042). EQ-VAS scores of MSCs group improved significantly at 2 month (p = 0.023) and continued until the end of the 6-month visit (p = 0.002) in comparison to the placebo group. The timed up and go (TUG) physical performance test revealed significant group difference and showed continual enhancements over 6 months (p < 0.05). MSC transplantation improved the function of 4-m walking test (4MWT) compared with the placebo group with a decrease of 2.05 s at 6 months of follow-up (p = 0.21). The measurement of grip strength revealed group difference with MSCs group demonstrating better performance, particularly at 6 months (p = 0.002). Inflammatory cytokines (TNF-α, IL-17) exhibited declines in MSCs group at 6 months compared to the placebo group (p = 0.034 and 0.033, respectively). There was no difference of incidence of AEs between the two groups.

CONCLUSION

Intravenous transplantation of HUC-MSCs is a safe and effective therapeutic approach on aging frailty. The positive outcomes observed in improving quality of life, physical performance, and reducing chronic inflammation, suggest that HUC-MSC therapy may be a promising potential treatment option for aging frailty.

TRIAL REGISTRATION

Clinicaltrial.gov; NCT04314011; https://clinicaltrials.gov/ct2/show/NCT04314011 .

Clinical aspects of umbilical cord cannulation during transfer from the uterus to a liquid-based perinatal life support system for extremely premature infants a qualitative generic study

A liquid-based perinatal life support system (PLS) for extremely premature infants (born before 28 week of gestational age) envisions a connection between the infant's native umbilical cord and an artificial placenta system through cannulation. This system mimics a natural mothers' womb to achieve better organ maturations. The objective of this study is to gain insight into the clinical focus points of umbilical cord cannulation and how cannulation should be addressed in extremely premature infants during the transfer from the uterus to an in-utero simulating liquid-based PLS system. We performed an explorative qualitative study. Twelve medical specialists with knowledge of vessel cannulation participated. We collected data through twelve interviews and two focus group discussions. Data were analyzed using inductive content and constant comparison analysis via open and axial coding. Results were derived on the following topics: (1) cannulation technique, (2) cannula fixation, (3) local and systemic anticoagulation, and (4) vasospasm. A side-entry technique is preferred as this may decrease wall damage, stabilizes the vessel better and ensures continuous blood flow. Sutures, especially via an automatic microsurgery instrument, are favored above glue, stents, or balloons as these may be firmer and faster. Medication possibilities for both vasospasm and anticoagulation should function locally since there were uncertainties regarding the systemic effects. According to the findings of this research, the needed umbilical cord cannulation method should include minimal wall damage, improved vascular stability, blood flow maintenance, a strong fixation connection, and local anticoagulation effect.

Inflammation-inducible promoters to overexpress immune inhibitory factors by MSCs

BACKGROUND

Mesenchymal stromal cells (MSCs) are excessively investigated in the context of inflammation-driven diseases, but the clinical results are often moderate. MSCs are naturally activated by inflammatory signals, which lead to the secretion of immune inhibitory factors in inflamed tissues. Many work groups try to improve the therapeutic outcome of MSCs by genetic modification and the constitutive overexpression of immune modulatory transgenes. However, the ectopic secretion of immune inhibitory transgenes increases the chances of infections, and constitutive transgene expression is not necessary for chronic diseases undergoing different inflammatory stages.

METHODS

We designed and tested inflammation-induced promoters to control transgene expression from integrating lentiviral vectors in human umbilical cord MSCs. Therefore, we investigated different combinations of general transcription factor elements to achieve a minimal promoter with low basal activity. The best candidates were combined with interferon-induced GAS or ISRE DNA motifs. The constructs with the highest transgene expression upon addition of pro-inflammatory cytokines were compared to vectorized promoters from inflammation-induced genes (CD317, CXCL9, CXCL10, CXCL11 and IDO1). Finally, we investigated IL10 as a potential immune inhibitory transgene by transcriptome analyses, ELISA and in an acute lung injury mouse model.

RESULTS

The synthetic promoters achieved a high and specific transgene expression upon IFN-γ addition. However, the CXCL11 promoter showed synergistic activity upon IFN-γ, TNF-α and IL1-β treatment and surpassed the transgene expression height of all tested promoters in the study. We observed in transcriptome analyses that IL10 has no effect on MSCs and in ELISA that IL10 is only secreted by our genetically modified and activated CXCL11-IL10-MSCs. Finally, transplanted CXCL11-IL10-MSCs increased CD19+ and CD4+ lymphoid cells, and decreased CD11b+ Ly6g myeloid cells in an ALI mouse model.

CONCLUSION

These results provide new insights into MSC inflammatory activation and the subsequent translation into a tool for a tailored expression of transgenes in inflammatory microenvironments. The newly developed promoter elements are potentially interesting for other inflamed tissues, and can be combined with other elements or used in other cell types.

Preparation of Fibrinogen-Depleted Human Platelet Lysate to Support Heparin-Free Expansion of Umbilical Cord-Derived Mesenchymal Stem Cells

Human platelet lysate (hPL) has high levels of fibrinogen and coagulation factors, which can lead to gel and precipitate formation during storage and cell culture. Heparin derived from animals is commonly added to minimize these risks, but cannot completely eliminate them. Thus, this study proposes an alternative method to prepare fibrinogen-depleted hPL (Fd-hPL) that supports heparin-free expansion of mesenchymal stem cells (MSCs). hPL was added to heparin to prepare heparin-hPL (H-hPL), whilst Fd-hPL was prepared by adding calcium salt to hPL to remove the fibrin clot. The concentrations of calcium, fibrinogen, and growth factors in H-hPL and Fd-hPL were compared. The effects of H-hPL and Fd-hPL on umbilical cord-derived MSCs (UC-MSCs) were assessed. The results showed that Fd-hPL possessed a significantly higher calcium concentration and a lower fibrinogen level than H-hPL. The concentrations of BDNF, TGF-β1, and PDGF-BB showed no significant difference between H-hPL and Fd-hPL, but Fd-hPL had a lower VEGF concentration. Fd-hPL retained the characteristics of UC-MSCs, as it did not affect the cell viability, proliferation, multilineage differentiation potential, or surface marker expression. In conclusion, Fd-hPL effectively supported the in vitro expansion of MSCs without compromising their characteristics, positioning it as a potential substitute for FBS in MSC culture.

Umbilical cord-derived mesenchymal stromal cells preserve endogenous insulin production in type 1 diabetes: a Phase I/II randomised double-blind placebo-controlled trial

AIM/HYPOTHESIS

This study aimed to investigate the safety and efficacy of treatment with allogeneic Wharton's jelly-derived mesenchymal stromal cells (MSCs) in recent-onset type 1 diabetes.

METHODS

A combined Phase I/II trial, composed of a dose escalation followed by a randomised double-blind placebo-controlled study in parallel design, was performed in which treatment with allogeneic MSCs produced as an advanced therapy medicinal product (ProTrans) was compared with placebo in adults with newly diagnosed type 1 diabetes. Inclusion criteria were a diagnosis of type 1 diabetes <2 years before enrolment, age 18-40 years and a fasting plasma C-peptide concentration >0.12 nmol/l. Randomisation was performed with a web-based randomisation system, with a randomisation code created prior to the start of the study. The randomisation was made in blocks, with participants randomised to ProTrans or placebo treatment. Randomisation envelopes were kept at the clinic in a locked room, with study staff opening the envelopes at the baseline visits. All participants and study personnel were blinded to group assignment. The study was conducted at Karolinska University Hospital, Stockholm, Sweden.

RESULTS

Three participants were included in each dose cohort during the first part of the study. Fifteen participants were randomised in the second part of the study, with ten participants assigned to ProTrans treatment and five to placebo. All participants were analysed for the primary and secondary outcomes. No serious adverse events related to treatment were observed and, overall, few adverse events (mainly mild upper respiratory tract infections) were reported in the active treatment and placebo arms. The primary efficacy endpoint was defined as Δ-change in C-peptide AUC for a mixed meal tolerance test at 1 year following ProTrans/placebo infusion compared with baseline performance prior to treatment. C-peptide levels in placebo-treated individuals declined by 47%, whereas those in ProTrans-treated individuals declined by only 10% (p<0.05). Similarly, insulin requirements increased in placebo-treated individuals by a median of 10 U/day, whereas insulin needs of ProTrans-treated individuals did not change over the follow-up period of 12 months (p<0.05).

CONCLUSIONS/INTERPRETATION

This study suggests that allogeneic Wharton's jelly-derived MSCs (ProTrans) is a safe treatment for recent-onset type 1 diabetes, with the potential to preserve beta cell function.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03406585 FUNDING: The sponsor of the clinical trial is NextCell Pharma AB, Stockholm, Sweden.

Inhibition of LPS-Induced Inflammatory Response of Oral Mesenchymal Stem Cells in the Presence of Galectin-3

Galectin-3 (GAL-3) is a beta-galactoside binding lectin produced by mesenchymal stem cells (MSCs) and other cell sources under inflammatory conditions. Several studies have reported that GAL-3 exerts an anti-inflammatory action, regulated by its natural ligand GAL-3 BP. In the present study, we aimed to assess the GAL-3 mediated regulation of the MSC function in an LPS-induced inflammation setting. Human gingival mesenchymal stem cells (hGMSCs) were stimulated in vitro with LPSs; the expression of TLR4, NFκB p65, MyD88 and NALP3 were assessed in the hGMSCs via immunofluorescence imaging using confocal microscopy, Western blot assay, and RT-PCR before and after the addition of GAL-3, both alone and with the addition of its inhibitors. LPSs stimulated the expression of TLR4, NFκB p65, MyD88 and NALP3 in hGMSCs, which was inhibited by GAL-3. The addition of either GAL3-BP or the antibody to GAL-3 were able to revert the GAL-3-mediated effects, restoring the expression of TLR4, NFκB p65, MyD88 and NALP3. GAL-3 induces the downregulation of the LPS-induced inflammatory program in MSCs.

Subcellular spatially resolved gene neighborhood networks in single cells

Image-based spatial omics methods such as fluorescence in situ hybridization (FISH) generate molecular profiles of single cells at single-molecule resolution. Current spatial transcriptomics methods focus on the distribution of single genes. However, the spatial proximity of RNA transcripts can play an important role in cellular function. We demonstrate a spatially resolved gene neighborhood network (spaGNN) pipeline for the analysis of subcellular gene proximity relationships. In spaGNN, machine-learning-based clustering of subcellular spatial transcriptomics data yields subcellular density classes of multiplexed transcript features. The nearest-neighbor analysis produces heterogeneous gene proximity maps in distinct subcellular regions. We illustrate the cell-type-distinguishing capability of spaGNN using multiplexed error-robust FISH data of fibroblast and U2-OS cells and sequential FISH data of mesenchymal stem cells (MSCs), revealing tissue-source-specific MSC transcriptomics and spatial distribution characteristics. Overall, the spaGNN approach expands the spatial features that can be used for cell-type classification tasks.

Harmonised culture procedures minimise but do not eliminate mesenchymal stromal cell donor and tissue variability in a decentralised multicentre manufacturing approach

BACKGROUND

Mesenchymal stromal cells (MSCs), commonly sourced from adipose tissue, bone marrow and umbilical cord, have been widely used in many medical conditions due to their therapeutic potential. Yet, the still limited understanding of the underlying mechanisms of action hampers clinical translation. Clinical potency can vary considerably depending on tissue source, donor attributes, but importantly, also culture conditions. Lack of standard procedures hinders inter-study comparability and delays the progression of the field. The aim of this study was A- to assess the impact on MSC characteristics when different laboratories, performed analysis on the same MSC material using harmonised culture conditions and B- to understand source-specific differences.

METHODS

Three independent institutions performed a head-to-head comparison of human-derived adipose (A-), bone marrow (BM-), and umbilical cord (UC-) MSCs using harmonised culture conditions. In each centre, cells from one specific tissue source were isolated and later distributed across the network to assess their biological properties, including cell expansion, immune phenotype, and tri-lineage differentiation (part A). To assess tissue-specific function, angiogenic and immunomodulatory properties and the in vivo biodistribution were compared in one expert lab (part B).

RESULTS

By implementing a harmonised manufacturing workflow, we obtained largely reproducible results across three independent laboratories in part A of our study. Unique growth patterns and differentiation potential were observed for each tissue source, with similar trends observed between centres. Immune phenotyping verified expression of typical MSC surface markers and absence of contaminating surface markers. Depending on the established protocols in the different laboratories, quantitative data varied slightly. Functional experiments in part B concluded that conditioned media from BM-MSCs significantly enhanced tubulogenesis and endothelial migration in vitro. In contrast, immunomodulatory studies reported superior immunosuppressive abilities for A-MSCs. Biodistribution studies in healthy mice showed lung entrapment after administration of all three types of MSCs, with a significantly faster clearance of BM-MSCs.

CONCLUSION

These results show the heterogeneous behaviour and regenerative properties of MSCs as a reflection of intrinsic tissue-origin properties while providing evidence that the use of harmonised culture procedures can reduce but do not eliminate inter-lab and operator differences.

Obesity and Wound Healing: Focus on Mesenchymal Stem Cells

Chronic wounds represent nowadays a major challenge for both clinicians and researchers in the regenerative setting. Obesity represents one of the major comorbidities in patients affected by chronic ulcers and therefore diverse studies aimed at assessing possible links between these two morbid conditions are currently ongoing. In particular, adipose tissue has recently been described as having metabolic and endocrine functions rather than serving as a mere fat storage deposit. In this setting, adipose-derived stem cells, a peculiar subset of mesenchymal stromal/stem cells (MSCs) located in adipose tissue, have been demonstrated to possess regenerative and immunological functions with a key role in regulating both adipocyte function and skin regeneration. The aim of the present review is to give an overview of the most recent findings on wound healing, with a special focus on adipose tissue biology and obesity.

Evaluation of the Optimal Manufacturing Protocols and Therapeutic Properties of Mesenchymal Stem/Stromal Cells Derived from Wharton's Jelly

Wharton's jelly (WJ) from the umbilical cord (UC) is a good source of mesenchymal stem/stromal cells (MSCs), which can be isolated and used in therapy. Current knowledge shows that even small changes in the cell environment may result in obtaining a subpopulation of cells with different therapeutic properties. For this reason, the conditions of UC transportation, cell isolation, and cultivation and the banking of cells destined for clinical use should be unified and optimized. In this project, we tried various protocols for cell vs. bioptat isolation, banking, and transport in order to determine the most optimal. The most efficient isolation method of WJ-MSCs was chopping the whole umbilical matrix with a scalpel after vessel and lining membrane removal. The optimal solution for short term cell transportation was a multi-electrolyte fluid without glucose. Considering the use of WJ-MSCs in cell therapies, it was important to investigate the soluble secretome of both WJ bioptats and WJ-MSCs. WJ-MSCs secreted higher levels of cytokines and chemokines than WJ bioptats. WJ-MSCs secreted HGF, CCL2, ICAM-1, BDNF, and VEGF. Since these cells might be used in treating neurodegenerative disorders, we investigated the impact of cerebrospinal fluid (CSF) on WJ-MSCs' features. In the presence of CSF, the cells expressed consecutive neural markers both at the protein and gene level: nestin, β-III-tubulin, S-100-β, GFAP, and doublecortin. Based on the obtained results, a protocol for manufacturing an advanced-therapy medicinal product was composed.

Mesenchymal Stem Cells and MSCs-Derived Extracellular Vesicles in Infectious Diseases: From Basic Research to Clinical Practice

Mesenchymal stem cells (MSCs) are attractive in various fields of regenerative medicine due to their therapeutic potential and complex unique properties. Basic stem cell research and the global COVID-19 pandemic have given impetus to the development of cell therapy for infectious diseases. The aim of this review was to systematize scientific data on the applications of mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (MSC-EVs) in the combined treatment of infectious diseases. Application of MSCs and MSC-EVs in the treatment of infectious diseases has immunomodulatory, anti-inflammatory, and antibacterial effects, and also promotes the restoration of the epithelium and stimulates tissue regeneration. The use of MSC-EVs is a promising cell-free treatment strategy that allows solving the problems associated with the safety of cell therapy and increasing its effectiveness. In this review, experimental data and clinical trials based on MSCs and MSC-EVs for the treatment of infectious diseases are presented. MSCs and MSC-EVs can be a promising tool for the treatment of various infectious diseases, particularly in combination with antiviral drugs. Employment of MSC-derived EVs represents a more promising strategy for cell-free treatment, demonstrating a high therapeutic potential in preclinical studies.

Close-to-native bone repair via tissue-engineered endochondral ossification approaches

In order to solve the clinical challenges related to bone grafting, several tissue engineering (TE) strategies have been proposed to repair critical-sized defects. Generally, the classical TE approaches are designed to promote bone repair via intramembranous ossification. Although promising, strategies that direct the osteogenic differentiation of mesenchymal stem/stromal cells are usually characterized by a lack of functional vascular supply, often resulting in necrotic cores. A less explored alternative is engineering bone constructs through a cartilage-mediated approach, resembling the embryological process of endochondral ossification. The remodeling of an intermediary hypertrophic cartilaginous template triggers vascular invasion and bone tissue deposition. Thus, employing this knowledge can be a promising direction for the next generation of bone TE constructs. This review highlights the most recent biomimetic strategies for applying endochondral ossification in bone TE while discussing the plethora of cell types, culture conditions, and biomaterials essential to promote a successful bone regeneration process.

The dark side of adipose-derived mesenchymal stromal cells in cutaneous oncology: roles, expectations, and potential pitfalls

Adipose-derived stromal cells (ADSCs) have well-established regenerative and immunomodulatory properties. For such reasons, ADSCs are currently under investigation for their use in the setting of both regenerative medicine and autoimmune diseases. As per dermatological disorders, MSC-based strategies represent potential therapeutic tools not only for chronic ulcers and wound healing, but also for immune-mediated dermatoses. However, a growing body of research has been focusing on the role of MSCs in human cancers, due to the potential oncological risk of using MSC-based strategies linked to their anti-apoptotic, pro-angiogenic and immunosuppressive properties. In the dermatological setting, ADSCs have shown not only to promote melanoma growth and invasiveness, but also to induce drug-resistance. On the other hand, genetically modified ADSCs have been demonstrated to efficiently target therapies at tumor sites, due to their migratory properties and their peculiar tropism for cancer microenvironment. The present review briefly summarizes the findings published so far on the use of ADSCs in the dermato-oncological setting, with the majority of data being available for melanoma.

Interleukins Profiling in Umbilical Cord Mesenchymal Stem Cell-Derived Secretome

Background

Umbilical cord mesenchymal stem cells (UC-MSCs)-derived secretome is currently used in regenerative therapy. MSCs are believed to secrete a wide spectrum of bioactive molecules which give paracrine effects in immunomodulation and regenerative capacities. One group that was found in secretome is interleukins (ILs), a cytokine that plays an essential role in the process of proliferation, differentiation, maturation, migration, and adhesion of immune cells. However, as there are many types of ILs, the profile of ILs in the UC-MSCs-derived secretome has been limitedly reported. Therefore, in this study, we would like to profile and detect the interleukin concentration secreted by UC-MSCs.

Methods

UC-MSCs-derived secretome was collected from UC-MSCs passage 5 after 24- and 48-hour incubation (n=9). Secretome was filtered using 0.2 µm and stored at -80°C for further detection. All samples were normalized before the interleukin (IL-2, IL-4, IL-6, IL-9, IL-10, IL-12, IL-17A) detection using a MACSPlex Cytokine Kit.

Results

The IL-6 has the highest concentration among other interleukins in both groups and increases significantly (p<0.003) after incubation for 48 hours. The pro-inflammatory factors are decreasing while anti-inflammatory factors are increasing after 48-hour incubation.

Discussion

Our studies show that the UC-MSCs secrete pro- and anti-inflammatory interleukins. The concentration of anti-inflammatory interleukins shows to be increasing, while the pro-inflammatory interleukins are decreasing within the longer incubation time, but this not be applicable for IL-10 and IL-6. IL-6 has the highest concentration among other ILs. These results may provide important clues regarding when is the right time for secretome to be used in therapy patients, because all the molecules in the secretome can lead to many clinical manifestations.

Mesenchymal stromal cells promote the proliferation of basal stem cells and efficient epithelization in organotypic models of wound healing

Adipose derived mesenchymal stromal cells (ADSCs) represent a fascinating tool in the scenario of wound healing and regenerative medicine. Recent data already demonstrated that ADSCs could exert a stimulatory action on epithelial cells through secretion of soluble factors. The aim of the present study was to assess how ADSCs guide wound re‐epithelization in vitro in the presence of keratinocytes. We used an organotypic model of wound healing and we seeded keratinocytes on a ADSC‐induced dermal matrix. Conventional hematoxylin–eosin stain and immunohistochemistry staining for Ki67, p63 and pan‐keratins were performed at different timepoints. Histological sections of organotypic cultures showed complete coverage of the ADSC‐induced matrix by keratinocytes. Proliferation of basal stem cells was found to be the main mechanism responsible for epithelization of the dermis. In conclusion, ADSC do not only stimulate dermal regeneration through collagen deposition but also promote epithelization.

Immunomodulating Profile of Dental Mesenchymal Stromal Cells: A Comprehensive Overview

Dental mesenchymal stromal cells (MSCs) are multipotent cells present in dental tissues, characterized by plastic adherence in culture and specific surface markers (CD105, CD73, CD90, STRO-1, CD106, and CD146), common to all other MSC subtypes. Dental pulp, periodontal ligament, apical papilla, human exfoliated deciduous teeth, alveolar bone, dental follicle, tooth germ, and gingiva are all different sources for isolation and expansion of MSCs. Dental MSCs have regenerative and immunomodulatory properties; they are scarcely immunogenic but actively modulate T cell reactivity. in vitro studies and animal models of autoimmune diseases have provided evidence for the suppressive effects of dental MSCs on peripheral blood mononuclear cell proliferation, clearance of apoptotic cells, and promotion of a shift in the Treg/Th17 cell ratio. Appropriately stimulated MSCs produce anti-inflammatory mediators, such as transforming growth factor-β (TGF-β), prostaglandin E2, and interleukin (IL)-10. A particular mechanism through which MSCs exert their immunomodulatory action is via the production of extracellular vesicles containing such anti-inflammatory mediators. Recent studies demonstrated MSC-mediated inhibitory effects both on monocytes and activated macrophages, promoting their polarization to an anti-inflammatory M2-phenotype. A growing number of trials focusing on MSCs to treat autoimmune and inflammatory conditions are ongoing, but very few use dental tissue as a cellular source. Recent results suggest that dental MSCs are a promising therapeutic tool for immune-mediated disorders. However, the exact mechanisms responsible for dental MSC-mediated immunosuppression remain to be clarified, and impairment of dental MSCs immunosuppressive function in inflammatory conditions and aging must be assessed before considering autologous MSCs or their secreted vesicles for therapeutic purposes.

Investigating Optimal Autologous Cellular Platforms for Prenatal or Perinatal Factor VIII Delivery to Treat Hemophilia A

Patients with the severe form of hemophilia A (HA) present with a severe phenotype, and can suffer from life-threatening, spontaneous hemorrhaging. While prophylactic FVIII infusions have revolutionized the clinical management of HA, this treatment is short-lived, expensive, and it is not available to many A patients worldwide. In the present study, we evaluated a panel of readily available cell types for their suitability as cellular vehicles to deliver long-lasting FVIII replacement following transduction with a retroviral vector encoding a B domain-deleted human F8 transgene. Given the immune hurdles that currently plague factor replacement therapy, we focused our investigation on cell types that we deemed to be most relevant to either prenatal or very early postnatal treatment and that could, ideally, be autologously derived. Our findings identify several promising candidates for use as cell-based FVIII delivery vehicles and lay the groundwork for future mechanistic studies to delineate bottlenecks to efficient production and secretion of FVIII following genetic-modification.

Feasibility of reduced-dose posttransplant cyclophosphamide and cotransplantation of peripheral blood stem cells and umbilical cord-derived mesenchymal stem cells for SAA

Posttransplant cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis is an effective strategie for patients receiving matched sibling donor hematopoietic stem cell transplantation (MSD-HSCT) and haploidentical HSCT (haplo-HSCT). We evaluated the effectiveness and safety of reduced-dose cyclophosphamide, 20 mg/kg for 13 patients in MSD-HSCT cohort and 25 mg/kg for 22 patients in haplo-HSCT cohort, on days + 3, + 4 combined with cotransplantation of peripheral blood stem cells (PBSCs) and human umbilical cord-derived mesenchymal stem cells (UC-MSCs) for severe aplastic anemia (SAA). In MSD-PTCy cohort, the times to neutrophil and platelet engraftment were significantly shorter than those in the MSD-control cohort (P < 0.05). The cumulative incidence of acute GVHD (aGVHD) at day + 100 (15.4%) was lower than that in the MSD-control cohort (P = 0.050). No patient developed chronic GVHD (cGVHD). The 1-year overall survival (OS) and event-free survival (EFS) rates were 100% and 92.3%. In haplo-PTCy cohort, the times to neutrophil and platelet engraftment were significantly shorter than those in the haplo-control cohort (P < 0.05). The cumulative incidences of aGVHD at day + 100 and 1-year cGVHD were 31.8% and 18.2%, and the 1-year OS and EFS rates were 81.8% and 66.9%. Reduced-dose PTCy and cotransplantation of PBSCs and UC-MSCs is an acceptable alternative to patients with SAA.

Cell culture media notably influence properties of human mesenchymal stroma/stem-like cells from different tissues

BACKGROUND AIMS

Mesenchymal stroma/stem-like cells (MSCs) are a popular cell source and hold huge therapeutic promise for a broad range of possible clinical applications. However, to harness their full potential, current limitations in harvesting, expansion and characterization have to be overcome. These limitations are related to the heterogeneity of MSCs in general as well as to inconsistent experimental protocols. Here we aim to compare in vitro methods to facilitate comparison of MSCs generated from various tissues.

METHODS

MSCs from 3 different tissues (bone marrow, dental pulp, adipose tissue), exemplified by cells from 3 randomly chosen donors per tissue, were systematically compared with respect to their in vitro properties after propagation in specific in-house standard media, as established in the individual laboratories, or in the same commercially available medium.

RESULTS

Large differences were documented with respect to the expression of cell surface antigens, population doubling times, basal expression levels of 5 selected genes and osteogenic differentiation. The commercial medium reduced differences in these parameters with respect to individual human donors within tissue and between tissues. The extent, size and tetraspanin composition of extracellular vesicles were also affected.

CONCLUSIONS

The results clearly demonstrate the extreme heterogeneity of MSCs, which confirms the problem of reproducibility of results, even when harmonizing experimental conditions, and questions the significance of common parameters for MSCs from different tissues in vitro.

Off-the-shelf mesenchymal stem cells from human umbilical cord tissue can significantly improve symptoms in COVID-19 patients: An analysis of evidential relations

Coronavirus disease-2019 (COVID-19) has affected more than 200 countries worldwide. This disease has hugely affected healthcare systems as well as the economy to an extent never seen before. To date, COVID-19 infection has led to about 165000 deaths in 150 countries. At present, there is no specific drug or efficient treatment for this disease. In this analysis based on evidential relationships of the biological characteristics of MSCs, especially umbilical cord (UC)-derived MSCs as well as the first clinical trial using MSCs for COVID-19 treatment, we discuss the use of UC-MSCs to improve the symptoms of COVID-19 in patients.

Limited Potential or Unfavorable Manipulations? Strategies Toward Efficient Mesenchymal Stem/Stromal Cell Applications

Despite almost 50 years of research and over 20 years of preclinical and clinical studies, the question of curative potential of mesenchymal stem/stromal cells (MSCs) is still widely discussed in the scientific community. Non-reproducible treatment outcomes or even absence of treatment effects in comparison to control groups challenges the potential of these cells for routine application both in tissue engineering and in regenerative medicine. One of the reasons of such outcomes is non-standardized and often disadvantageous ex vivo manipulation of MSCs prior therapy. In most cases, clinically relevant cell numbers for MSC-based therapies can be only obtained by in vitro expansion of isolated cells. In this mini review, we will discuss point by point possible pitfalls in the production of human MSCs for cell therapies, without consideration of material-based applications. Starting with cell source, choice of donor and recipient, as well as isolation methods, we will then discuss existing expansion protocols (two-/three-dimensional cultivation, basal medium, medium supplements, static/dynamic conditions, and hypoxic/normoxic conditions) and influence of these strategies on the cell functionality after implantation. The role of potency assays will also be addressed. The final aim of this mini review is to illustrate the heterogeneity of current strategies for gaining MSCs for clinical applications with their strengths and weaknesses. Only a careful consideration and standardization of all pretreatment processes/methods for the different applications of MSCs will ensure robust and reproducible performance of these cell populations in the different experimental and clinical settings.

Primary Cilia Mediate Wnt5a/β-catenin Signaling to Regulate Adipogenic Differentiation of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells Following Calcium Induction

BACKGROUND

Regeneration of soft tissue defects is essential for adipose tissue pathologies and disease, trauma, or injury-induced damage. Here, we show that umbilical cord blood-derived mesenchymal stem cells could potentially be tailored and used for the reconstruction of specific damaged sites. Adipogenesis can be exploited in soft tissue reconstruction. Also, primary cilia play a role in the control of adipogenesis.

METHODS

The adipogenic differentiation capacity of mesenchymal stem cells (MSCs) was shown to influence ciliogenesis. MSCs transfected with intraflagellar transport 88 (IFT88) small interfering RNA (siRNA), which blocks the assembly and maintenance of cilia, were examined to confirm the relationship between adipogenesis and ciliogenesis. Also, 1,2-Bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM), calcium chelator, inhibited the ciliogenesis of MSCs in adipogenic differentiation.

RESULTS

IFT88-knockdown led to decreased cilia formation and limitation of cilia elongation in adipogenesis. Additionally, intracellular calcium triggered cilia formation in MSCs adipogenesis. Interestingly, intracellular calcium cannot overcome the inhibition of adipogenesis caused by low numbers of cilia in MSCs.

CONCLUSION

Our data suggested that ciliogenesis was negatively regulated by Wnt5a/β-catenin signaling during adipogenesis. Thus, we suggest that calcium induction triggers adipogenesis and ciliogenesis.