Characterization and therapeutic applications of mesenchymal stem cells for regenerative medicine. Tissue Cell. 2020;64:101330. [PMID: 32473704 DOI: 10.1016/j.tice.2020.101330]

Reconstruction of rabbit corneal epithelium using adipose and / or bone marrow stem cells

One of the main causes of corneal blindness is corneal alkali burn, which can also result in serious side effects such as limbal stem cell deficit, corneal perforation, and permanent epithelial abnormalities. This study set out to investigate the therapeutic potential of ADMSCs and BMMSCs for the reconstruction of the corneal surface after chemical alkali burn. Twelve adult rabbits were divided equally into four groups. Each rabbit in the other groups had a chemical alkali burn applied to their right eye using 6 mm-wide NaoH soaked filter paper, while the negative control group had no intervention. All groups except negative control group received topical and subconjunctival injections. Group I (Negative control) received no therapy, whereas Group II received an injection of phosphate-buffered saline as the positive control. Group III received 1 mL of ADMSCs, while Group IV received 1 mL of BMMSCs. After 4 weeks, the corneal tissue underwent morphological, histological, immunohistochemical examination and gene expression. The ocular tissue underwent histopathological examination revealed re-epithelialization and nearly normal architecture in the BMMSC-treated group. The injured cornea treated with ADMSCs showed partial repair of the anterior epithelium, in addition to inflammatory cells infiltration. An immunohistochemical analysis revealed that, compared to ADMSCs and positive control groups, the majority of the stromal cells in the cornea treated by BMMSCs exhibited robust positive expression of vimentin and Ki67. BMMSCs exhibited considerably higher levels of gene expression for corneal indicators, such as keratin 12 and connexin 43, in comparison to other groups. In treating a corneal chemical burn, this study shows that MSCs produced from bone marrow and adipose tissue effectively reduce tissue inflammation, enhance corneal tissue repair, and stimulate cell renewal, with BMMSCs showing better outcomes.

Mesenchymal stem/stromal cells alleviate early-stage pulmonary fibrosis in a uPAR-dependent manner

Pulmonary fibrosis, a debilitating lung disorder characterised by excessive fibrous tissue accumulation in lung parenchyma, compromises respiratory function leading to a life-threatening respiratory failure. While its origins are multifaceted and poorly understood, the urokinase system, including urokinase-type plasminogen activator (uPA) and its receptor (uPAR), plays a significant role in regulating fibrotic response, extracellular matrix remodelling, and tissue repair. Mesenchymal stem/stromal cells (MSCs) hold promise in regenerative medicine for treating pulmonary fibrosis. Our study aimed to investigate the potential of MSCs to inhibit pulmonary fibrosis as well as the contribution of uPAR expression to this effect. We found that intravenous MSC administration significantly reduced lung fibrosis in the bleomycin-induced pulmonary fibrosis model in mice as revealed by MRI and histological evaluations. Notably, administering the MSCs isolated from adipose tissue of uPAR knockout mice (Plaur-/- MSCs) attenuated lung fibrosis to a lesser extent as compared to WT MSCs. Collagen deposition, a hallmark of fibrosis, was markedly reduced in lungs treated with WT MSCs versus Plaur-/- MSCs. Along with that, endogenous uPA levels were affected differently; after Plaur-/- MSCs were administered, the uPA content was specifically decreased within the blood vessels. Our findings support the potential of MSC treatment in attenuating pulmonary fibrosis. We provide evidence that the observed anti-fibrotic effect depends on uPAR expression in MSCs, suggesting that uPAR might counteract the uPA accumulation in lungs.

Amine-reactive crosslinking enhances type 0 collagen hydrogel properties for regenerative medicine

Introduction

Collagen is extensively utilised in regenerative medicine due to its highly desirable properties. However, collagen is typically derived from mammalian sources, which poses several limitations, including high cost, potential risk of immunogenicity and transmission of infectious diseases, and ethical and religious constraints. Jellyfish-sourced type 0 collagen represents a safer and more environmentally sustainable alternative collagen source.

Methods

Thus, we investigated the potential of jellyfish collagen-based hydrogels, obtained from Rhizostoma pulmo (R. pulmo) jellyfish, to be utilised in regenerative medicine. A variety of R. pulmo collagen hydrogels (RpCol hydrogels) were formed by adding a range of chemical crosslinking agents and their physicochemical and biological properties were characterised to assess their suitability for regenerative medicine applications.

Results and Discussion

The characteristic chemical composition of RpCol was confirmed by Fourier-transform infrared spectroscopy (FTIR), and the degradation kinetics, morphological, and rheological properties of RpCol hydrogels were shown to be adaptable through the addition of specific chemical crosslinking agents. The endotoxin levels of RpCol were below the Food and Drug Administration (FDA) limit for medical devices, thus allowing the potential use of RpCol in vivo. 8-arm polyethylene glycol succinimidyl carboxyl methyl ester (PEG-SCM)-crosslinked RpCol hydrogels preserved the viability and induced a significant increase in the metabolic activity of immortalised human mesenchymal stem/stromal cells (TERT-hMSCs), therefore demonstrating their potential to be utilised in a wide range of regenerative medicine applications.

Mesenchymal stromal cells derived from various tissues: Biological, clinical and cryopreservation aspects: Update from 2015 review

Mesenchymal stromal cells (MSCs) have become one of the most investigated and applied cells for cellular therapy and regenerative medicine. In this update of our review published in 2015, we show that studies continue to abound regarding the characterization of MSCs to distinguish them from other similar cell types, the discovery of new tissue sources of MSCs, and the confirmation of their properties and functions that render them suitable as a therapeutic. Because cryopreservation is widely recognized as the only technology that would enable the on-demand availability of MSCs, here we show that although the traditional method of cryopreserving cells by slow cooling in the presence of 10% dimethyl sulfoxide (Me2SO) continues to be used by many, several novel MSC cryopreservation approaches have emerged. As in our previous review, we conclude from these recent reports that viable and functional MSCs from diverse tissues can be recovered after cryopreservation using a variety of cryoprotectants, freezing protocols, storage temperatures, and periods of storage. We also show that for logistical reasons there are now more studies devoted to the cryopreservation of tissues from which MSCs are derived. A new topic included in this review covers the application in COVID-19 of MSCs arising from their immunomodulatory and antiviral properties. Due to the inherent heterogeneity in MSC populations from different sources there is still no standardized procedure for their isolation, identification, functional characterization, cryopreservation, and route of administration, and not likely to be a "one-size-fits-all" approach in their applications in cell-based therapy and regenerative medicine.

Sustainably cultured coral scaffold supports human bone marrow mesenchymal stromal cell osteogenesis

The current gold standard grafting material is autologous bone due to its osteoinductive and osteoconductive properties. Autograft harvesting results in donors site morbidity. Coral scaffolds offer a natural autograft alternative, sharing the density and porosity of human bone. This study investigated the biocompatibility and osteogenic potential of a novel, sustainably grown Pocillopora scaffold with human bone marrow-derived mesenchymal stromal cells (MSCs). The coral-derived scaffold displays a highly textured topography, with concavities of uniform size and a high calcium carbonate content. Large scaffold samples exhibit compressive and diametral tensile strengths in the range of trabecular bone, with strengths likely increasing for smaller particulate samples. Following the in vitro seeding of MSCs adjacent to the scaffold, the MSCs remained viable, continued proliferating and metabolising, demonstrating biocompatibility. The seeded MSCs densely covered the coral scaffold with organized, aligned cultures with a fibroblastic morphology. In vivo coral scaffolds with MSCs supported earlier bone and blood vessel formation as compared to control constructs containing TCP-HA and MSCs. This work characterized a novel, sustainably grown coral scaffold that was biocompatible with MSCs and supports their in vivo osteogenic differentiation, advancing the current repertoire of biomaterials for bone grafting.

Clinical observation on the safety and efficacy of umbilical cord mesenchymal stem cells in the treatment of bronchiolitis obliterans after allogeneic haematopoietic stem cell transplantation

Graft-versus-host disease (GVHD) is caused by a pathologic and destructive response of the organism as a result of the interaction between donor immunocompetent T lymphocytes and the recipient tisular antigens1. Graft-versus-host disease is considered a serious complication of hematopoietic stem cell transplantation. The skin, oral cavity and lungs are commonly affected organs. Among these complications bronchiolitis obliterans syndrome is a serious complication, which even can be life-threatening. Therefore, this research aims to do a clinical observation on the safety and efficacy of umbilical cord mesenchymal stem cells in the treatment of bronchiolitis obliterans after allogeneic haematopoietic stem cell transplantation. Fifteen patients were included in this study, who received allogeneic hematopoietic stem cell transplantation. Among these patients, both of them were treated with azithromycin, montelukast, glucocorticoid and pirfenidone. Two of them did not receive second line anti-rejection treatment due to economic reasons, and three of them were treated with mesenchymal stem cells. These bronchiolitis obliterans syndrome-related symptoms such as shortness of breath, chest tightness and wheezing have improved. Two of them died due to bronchiolitis obliterans syndrome related complications such as respiratory failure. Two of them not only improve the symptoms but also increased the FEV1/FVC, who were treated with mesenchymal stem cells. The comprehensive treatment regimen containing imatinib and ruxolitinib is safe and effective and mesenchymal stem cell is a promising treatment option to improve the prognosis of post-HSCT BOS.

MiR-145-5p overexpression rejuvenates aged adipose stem cells and accelerates wound healing

Adipose-derived stem cells (ADSCs) have been widely applied in translational and regenerative medicine. During aging, there is a recognized functional decline in ADSCs, which compromises their therapeutic effectiveness. Currently, the mechanisms of aging-induced stem cell dysfunction remain unclear, hence there is a need to elucidate these mechanisms and propose strategies for reversing this functional impairment. In this study, we found that ADSCs isolated from old donors (O-ADSCs) presented inferior phenotypes and decreased miR-145-5p levels compared to those from young donors (Y-ADSCs). To interrogate the role of miR-145-5p in ADSCs, gain- and loss-of-function assays were performed. The results indicated that miR-145-5p overexpression in O-ADSCs promoted cellular proliferation and migration, while reducing cell senescence. Further study demonstrated that miR-145-5p could regulate ADSCs function by targeting bone morphogenetic protein binding endothelial cell precursor-derived regulator (BMPER), which is a crucial modulator in angiogenesis. Moreover, in vivo experiments showed that miR-145-5p-overexpressing O-ADSCs accelerated wound healing by promoting wound re-epithelialization and angiogenesis. Collectively, this study indicates that miR-145-5p works as a positive regulator for optimizing O-ADSCs function, and may be a novel therapeutic target for restoring aging-associated impairments in stem cell function.

Fucoxanthin Enhances the Antifibrotic Potential of Placenta-derived Mesenchymal Stem Cells in a CCl4-induced Mouse Model of Liver

BACKGROUND

The effectiveness of fucoxanthin (Fx) in liver diseases has been reported due to its anti-inflammatory and antifibrotic effects. Mesenchymal stem cells (MSCs)-based therapy has also been proposed as a promising strategy for liver fibrosis treatment. Recent studies have shown that the co-administration of MSCs and drugs demonstrates a pronounced effect on liver fibrosis.

AIM

This study aimed to determine the therapeutic potential of placenta-derived MSCs (PD-MSCs) in combination with Fx to treat liver fibrosis and evaluate their impact on the main links of liver fibrosis pathogenesis.

METHODS

After PD-MSCs isolation and identification, outbred ICR/CD1 mice were divided into five groups: Control group, CCl4 group (CCl4), Fx group (CCl4+Fx), PD-MSCs group (CCl4+MSCs) and cotreatment group (CCl4+MSCs+Fx). Biochemical histopathological investigations were performed. Semiquantitative analysis of the alpha-smooth muscle actin (α-SMA+), matrix metalloproteinases (MMP-9+, MMP-13+), tissue inhibitor of matrix metalloproteinases-1 (TIMP-1+) areas, and the number of positive cells in them were studied by immunohistochemical staining. Transforming growth factor-beta (TGF-β), hepatic growth factor (HGF), procollagen-1 (COL1α1) in liver homogenate and proinflammatory cytokines in blood serum were determined using an enzyme immunoassay.

RESULTS

Compared to the single treatment with PD-MSCs or Fx, their combined administration significantly reduced liver enzyme activity, the severity of liver fibrosis, the proinflammatory cytokine levels, TGF-β level, α-SMA+, TIMP-1+ areas and the number of positive cells in them, and increased HGF level, MMP-13+, and MMP-9+ areas.

CONCLUSION

Fx enhanced the therapeutic potential of PD-MSCs in CCl4-induced liver fibrosis, but more investigations are necessary to understand the mutual impact of PD-MSCs and Fx.

Silica Replicas Derived from Mammalian Cells as an Innovative Approach to Physically Direct Cell Lineage Decisions of Mesenchymal Stem Cells

By means of a "live-cell" template strategy, silica replicas displaying the same morphology and topography of the mammalian cells used as templates are fabricated. The replicas are used as substrates to direct the differentiation of mesenchymal stem cells (MSCs) to predefined cell lineages. Upregulation of specific genes shows how the silica replica-based substrates have the ability to induce the molecular characteristics of the mature cell types from which they have been derived from. Thus, MSCs cultured in the presence of silica replicas of human osteoblasts (HObs) differentiate into HObs-like cells, as shown by the upregulation of specific osteogenic genes. Likewise, when MSCs are incubated with silica replicas derived from human chondrocytes, an enhanced expression of chondrogenic markers is observed. Importantly, the effects of the silica replicas are cell type-specific since the incubation of MSCs with HObs silica replicas does not result in upregulation of chondrogenic markers and vice versa. What is more, for both cases, the differentiation rate is enhanced when the silica replicas are used in combination with growth factors, suggesting a potential synergistic effect. These results demonstrate the potential of this innovative method as an efficient and cheap approach with the potential to eliminate, or at least reduce, the use of biochemically soluble compounds in stem cells research.

Investigating the potential of oncolytic viruses for cancer treatment via MSC delivery

Mesenchymal stem cells (MSCs) have attracted considerable interest as a promising approach for cancer treatment due to their ability to undergo tumor-trophic migration. MSCs possess the unique ability to selectively migrate to tumors, making them an excellent candidate for targeted delivery of oncolytic viruses (OVs) to treat isolated tumors and metastatic malignancies. OVs have attracted attention as a potential treatment for cancer due to their ability to selectively infect and destroy tumor cells while sparing normal cells. In addition, OVs can induce immunogenic cell death and contain curative transgenes in their genome, making them an attractive candidate for cancer treatment in combination with immunotherapies. In combination with MSCs, OVs can modulate the tumor microenvironment and trigger anti-tumor immune responses, making MSC-releasing OVs a promising approach for cancer treatment. This study reviews researches on the use of MSC-released OVs as a novel method for treating cancer. Video Abstract.

In Vitro Study of a Novel Vibrio alginolyticus-Based Collagenase for Future Medical Application

Mesenchymal stem cells extracted from adipose tissue are particularly promising given the ease of harvest by standard liposuction and reduced donor site morbidity. This study proposes a novel enzymatic method for isolating stem cells using Vibrio alginolyticus collagenase, obtaining a high-quality product in a reduced time. Initially, the enzyme concentration and incubation time were studied by comparing cellular yield, proliferation, and clonogenic capacities. The optimized protocol was phenotypically characterized, and its ability to differentiate in the mesodermal lineages was evaluated. Subsequently, that protocol was compared with two Clostridium histolyticum-based collagenases, and other tests for cellular integrity were performed to evaluate the enzyme's effect on expanded cells. The best results showed that using a concentration of 3.6 mg/mL Vibrio alginolyticus collagenase allows extracting stem cells from adipose tissue after 20 min of enzymatic reaction like those obtained with Clostridium histolyticum-based collagenases after 45 min. Moreover, the extracted cells with Vibrio alginolyticus collagenase presented the phenotypic characteristics of stem cells that remain after culture conditions. Finally, it was seen that Vibrio alginolyticus collagenase does not reduce the vitality of expanded cells as Clostridium histolyticum-based collagenase does. These findings suggest that Vibrio alginolyticus collagenase has great potential in regenerative medicine, given its degradation selectivity by protecting vital structures for tissue restructuration.

Total Glucosides of Paeony Regulate Immune Imbalance Mediated by Dermal Mesenchymal Stem Cells in Psoriasis Mice

OBJECTIVE

To investigate the therapeutic effects of total glucosides of paeony (TGP) on psoriasis based on the immunomodulatory effect of dermal mesenchymal stem cells (DMSCs).

METHODS

A total of 30 male BALB/c mice were divided into 6 groups (n=5 in each) by a random number table method, including control, psoriasis model (model, 5% imiquimod cream 42 mg/d), low-, medium- and high-dose TGP (50, 100, and 200 mg/kg, L, M-, and H-TGP, respectively), and positive control group (2.5 mg/kg acitretin). After 14 days of continuous administration, the skin's histopathological changes, apoptosis, secretion of inflammatory cytokines, and proportion of regulatory T cells (Treg) and T helper cell 17 (Th17) were evaluated using hematoxylin-eosin (HE) staining, TdT-mediated dUTP nick end labeling staining, enzyme-linked immunosorbent assay, and flow cytometry, respectively. DMSCs were further isolated from the skin tissues of normal and psoriatic mice, and the cell morphology, phenotype, and cycle were observed. Furthermore, TGP was used to treat psoriatic DMSCs to analyze the effects on the DMSCs immune regulation.

RESULTS

TGP alleviated skin pathological injury, reduced epidermis layer thickness, inhibited apoptosis, and regulated the secretion of inflammatory cytokines and the proportion of Treg and Th17 in the skin tissues of psoriatic mice (P<0.05 or P<0.01). There was no significant difference in cell morphology and phenotype between control and psoriatic DMSCs (P>0.05), however, more psoriatic DMSCs remained in G₀/G₁ phase compared with the normal DMSCs (P<0.01). TGP treatment of psoriatic DMSCs significantly increased cell viability, decreased apoptosis, relieved inflammatory response, and inhibited the expression of toll-like receptor 4 and P65 (P<0.05 or P<0.01).

CONCLUSION

TGP may exert a good therapeutic effect on psoriasis by regulating the immune imbalance of DMSCs.

Chromatographic Scalable Method to Isolate Engineered Extracellular Vesicles Derived from Mesenchymal Stem Cells for the Treatment of Liver Fibrosis in Mice

New therapeutic options for liver cirrhosis are needed. Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) have emerged as a promising tool for delivering therapeutic factors in regenerative medicine. Our aim is to establish a new therapeutic tool that employs EVs derived from MSCs to deliver therapeutic factors for liver fibrosis. EVs were isolated from supernatants of adipose tissue MSCs, induced-pluripotent-stem-cell-derived MSCs, and umbilical cord perivascular cells (HUCPVC-EVs) by ion exchange chromatography (IEC). To produce engineered EVs, HUCPVCs were transduced with adenoviruses that code for insulin-like growth factor 1 (AdhIGF-I-HUCPVC-EVs) or green fluorescent protein. EVs were characterized by electron microscopy, flow cytometry, ELISA, and proteomic analysis. We evaluated EVs' antifibrotic effect in thioacetamide-induced liver fibrosis in mice and on hepatic stellate cells in vitro. We found that IEC-isolated HUCPVC-EVs have an analogous phenotype and antifibrotic activity to those isolated by ultracentrifugation. EVs derived from the three MSCs sources showed a similar phenotype and antifibrotic potential. EVs derived from AdhIGF-I-HUCPVC carried IGF-1 and showed a higher therapeutic effect in vitro and in vivo. Remarkably, proteomic analysis revealed that HUCPVC-EVs carry key proteins involved in their antifibrotic process. This scalable MSC-derived EV manufacturing strategy is a promising therapeutic tool for liver fibrosis.

Conditioned medium from human cord blood mesenchymal stem cells attenuates age-related immune dysfunctions

Aging is accompanied with progressive deterioration of immune responses and tissue's function. Using 12-month-old mice as model, we showed that conditioned medium of human cord blood mesenchymal stem cells (CBMSC-CM) significantly reduced the population percentage of CD3^-CD335⁺ NK and CD4⁺CD25⁺ regulatory T-cells in peripheral blood. The CBMSC-CM administration also increased naïve T-cells number and restored the ratio of naïve to memory T-cells in CD4⁺ T-cells population. These results indicated that CBMSC-CM improved the immune response efficiency of aged mice. Moreover, we also found CBMSC-CM treatment significantly reduced the number of senescenT-cells in kidney tissues. Finally, we demonstrated that CBMSC-CM remarkably attenuated hydrogen peroxide triggered T-cell response and ameliorated oxidative stress induced cellular senescence. All of these data suggest a prominent anti-aging effect of secretome of CBMSCs.

Carbon Quantum Dots for Stem Cell Imaging and Deciding the Fate of Stem Cell Differentiation

Nanotechnology advancements and applications have paved the way for new possibilities in regenerative medicine and tissue engineering. It is a relatively new field that has the potential to improve stem cell differentiation and therapy greatly. Numerous studies have demonstrated that nanomaterials can function as a physiological niche for the formation and differentiation of stem cells. However, quantum dots (QDs), such as carbon quantum dots (CQDs) and graphene quantum dots (GQDs), have shown considerable promise in the field of regenerative medicine. To date, most research has focused on stem cell tracking and imaging using CQDs. However, their interaction with stem cells and the associated possibility for differentiation by selectively focusing chemical signals to a particular lineage has received scant attention. In this mini-review, we attempt to categorize a few pathways linked with the role of CQDs in stem cell differentiation.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles as Biological Carriers for Drug Delivery in Cancer Therapy

Cancer is the second leading cause of death worldwide, with 10.0 million cancer deaths in 2020. Despite advances in targeted therapies, some pharmacological drawbacks associated with anticancer chemo and immunotherapeutic agents include high toxicities, low bioavailability, and drug resistance. In recent years, extracellular vesicles emerged as a new promising platform for drug delivery, with the advantage of their inherent biocompatibility and specific targeting compared to artificial nanocarriers, such as liposomes. Particularly, mesenchymal stem/stromal cells were proposed as a source of extracellular vesicles for cancer therapy because of their intrinsic properties: high in vitro self-renewal and proliferation, regenerative and immunomodulatory capacities, and secretion of extracellular vesicles that mediate most of their paracrine functions. Moreover, extracellular vesicles are static and safer in comparison with mesenchymal stem/stromal cells, which can undergo genetic/epigenetic or phenotypic changes after their administration to patients. In this review, we summarize currently reported information regarding mesenchymal stem/stromal cell-derived extracellular vesicles, their proper isolation and purification techniques - from either naive or engineered mesenchymal stem/stromal cells - for their application in cancer therapy, as well as available downstream modification methods to improve their therapeutic properties. Additionally, we discuss the challenges associated with extracellular vesicles for cancer therapy, and we review some preclinical and clinical data available in the literature.

Modulation of miR-204 Expression during Chondrogenesis

RUNX2 and SOX9 are two pivotal transcriptional regulators of chondrogenesis. It has been demonstrated that RUNX2 and SOX9 physically interact; RUNX2 transactivation may be inhibited by SOX9. In addition, RUNX2 exerts reciprocal inhibition on SOX9 transactivity. Epigenetic control of gene expression plays a major role in the alternative differentiation fates of stem cells; in particular, it has been reported that SOX9 can promote the expression of miRNA (miR)-204. Our aim was therefore to investigate the miR-204-5p role during chondrogenesis and to identify the relationship between this miR and the transcription factors plus downstream genes involved in chondrogenic commitment and differentiation. To evaluate the role of miR-204 in chondrogenesis, we performed in vitro transfection experiments by using Mesenchymal Stem Cells (MSCs). We also evaluated miR-204-5p expression in zebrafish models (adults and larvae). By silencing miR-204 during the early differentiation phase, we observed the upregulation of SOX9 and chondrogenic related genes compared to controls. In addition, we observed the upregulation of COL1A1 (a RUNX2 downstream gene), whereas RUNX2 expression of RUNX2 was slightly affected compared to controls. However, RUNX2 protein levels increased in miR-204-silenced cells. The positive effects of miR204 silencing on osteogenic differentiation were also observed in the intermediate phase of osteogenic differentiation. On the contrary, chondrocytes’ maturation was considerably affected by miR-204 downregulation. In conclusion, our results suggest that miR-204 negatively regulates the osteochondrogenic commitment of MSCs, while it positively regulates chondrocytes’ maturation.

Role of MSC-derived small extracellular vesicles in tissue repair and regeneration

Mesenchymal stem cells (MSCs) are crucial for tissue homeostasis and repair, secreting vesicles to the extracellular environment. Isolated exosomes were shown to affect angiogenesis, immunomodulation and tissue regeneration. Numerous efforts have been dedicated to describe the mechanism of action of these extracellular vesicles (EVs) and guarantee their safety, since the final aim is their therapeutic application in the clinic. The major advantage of applying MSC-derived EVs is their low or inexistent immunogenicity, prompting their use as drug delivery or therapeutic agents, as well as wound healing, different cancer types, and inflammatory processes in the neurological and cardiovascular systems. MSC-derived EVs display no vascular obstruction effects or apparent adverse effects. Their nano-size ensures their passage through the blood-brain barrier, demonstrating no cytotoxic or immunogenic effects. Several in vitro tests have been conducted with EVs obtained from different sources to understand their biology, molecular content, signaling pathways, and mechanisms of action. Application of EVs to human therapies has recently become a reality, with clinical trials being conducted to treat Alzheimer's disease, retina degeneration, and COVID-19 patients. Herein, we describe and compare the different extracellular vesicles isolation methods and therapeutic applications regarding the tissue repair and regeneration process, presenting the latest clinical trial reports.

Modern Approaches to Acellular Therapy in Bone and Dental Regeneration

An approach called cell-free therapy has rapidly developed in regenerative medicine over the past decade. Understanding the molecular mechanisms and signaling pathways involved in the internal potential of tissue repair inspires the development of new strategies aimed at controlling and enhancing these processes during regeneration. The use of stem cell mobilization, or homing for regeneration based on endogenous healing mechanisms, prompted a new concept in regenerative medicine: endogenous regenerative medicine. The application of cell-free therapeutic agents leading to the recruitment/homing of endogenous stem cells has advantages in overcoming the limitations and risks associated with cell therapy. In this review, we discuss the potential of cell-free products such as the decellularized extracellular matrix, growth factors, extracellular vesicles and miRNAs in endogenous bone and dental regeneration.

Single-cell transcriptome analysis defines mesenchymal stromal cells in the mouse incisor dental pulp

The dental pulp is known to be highly heterogenous, comprising distinct cell types including mesenchymal stromal cells (MSCs), which represent neural-crest-derived cells with the ability to differentiate into multiple cell lineages. However, the cellular heterogeneity and the transcriptome signature of different cell clusters within the dental pulp remain to be established. To better understand discrete cell types, we applied a single-cell RNA sequencing strategy to establish the RNA expression profiles of individual dental pulp cells from 5- to 6-day-old mouse incisors. Our study revealed distinct subclasses of cells representing osteoblast, odontoblast, endothelial, pancreatic, neuronal, immune, pericyte and ameloblast lineages. Collectively, our research demonstrates the complexity and diversity of cell subclasses within the incisor dental pulp, thus providing a foundation for uncovering the molecular processes that govern cell fate decisions and lineage commitment in dental pulp-derived MSCs.

Supercritical carbon dioxide dried double layer laponite XLS and alginate/polyacrylamide construct and immune response

Fabrication of immunocompatible tissue constructs for bone-cartilage defect regeneration is of prime importance. In this study, a double layer hydrogel was successfully synthesized, where alginate/polyacrylamide were formulated to represent cartilage layer (5-10 % (w/w) total polymer ratio) and laponite XLS (2-5-8% (w/w))/alginate/polyacrylamide formed bone layer. Hydrogels were dried by supercritical CO₂ at 100 and 200 bar, 45 °C, 5 g/min CO₂ flow rate for 2 h. Constructs were treated with collagen, then cellularized and embedded in cell-laden GelMA to mimic the cellular microenvironment. The optimum weight ratio of alginate/polyacrylamide:laponite XLS was 10:5 based on mechanical strength test results. The constructs yielded high porosity (91.50 m²/g) and mesoporous structure, owing to the diffusivity of CO₂ at 200 bar (0.49 × 10^-7  m²/s). Constructs were then treated with collagen to increase cell adhesion and ATDC5 cells were seeded in the cartilage layer, whereas hFOB cells to the bone layer. About 10-15 % higher cell viability was attained. The porous structure of the construct allowed infiltration of macrophages, promoted polarization and positively affected the behavior of macrophages, yielding a decrease in M1 markers, whereas an increase in M2 on day 4. The formulated tissue constructs would be of value in tissue engineering applications.

Regenerative Approaches for the Treatment of Large Bone Defects

A variety of engineered materials have gained acceptance in orthopedic practice as substitutes for autologous bone grafts, although the regenerative efficacy of these engineered grafts is still limited compared with that of transplanted native tissues. For bone defects greater than 4-5 cm, however, common bone grafting procedures are insufficient and more complicated surgical interventions are required to repair and regenerate the damaged or missing bone. In this review, we describe current grafting materials and surgical techniques for the reconstruction of large bone defects, followed by tissue engineering (TE) efforts to develop improved therapies. Particular emphasis is placed on graft vascularization, because for both autologous bone and engineered alternatives, achieving adequate vascular development within the regenerating bone tissues remains a significant challenge in the context of large bone defects. To this end, TE and surgical strategies to induce development of a vasculature within bone grafts are discussed. Impact statement This review aims to present an accessible and thorough overview of current orthopedic surgical techniques as well as bone tissue engineering and vascularization strategies that might one day offer improvements to clinical therapies for the repair of large bone defects. We consider the lessons that clinical orthopedic reconstructive practices can contribute to the push toward engineered bone.

Mesenchymal stem cell-derived exosomes: therapeutic implications for rotator cuff injury

Rotator cuff injuries are a common clinical condition of the shoulder joint. Surgery that involves reattaching the torn tendon to its humeral head bony attachment has a somewhat lower success rate. The scar tissue formed during healing of the rotator cuff leads to poor tendon-related mechanical properties. To promote healing, a range of genetic interventions, as well as cell transplantation, and many other techniques have been explored. In recent years, the therapeutic promise of mesenchymal stem cells (MSCs) has been well documented in animal and clinical studies. Some data have suggested that MSCs can promote angiogenesis, reduce inflammation and cell proliferation and increase collagen deposition. These functions are likely paracrine effects of MSCs, particularly mediated through exosomes. Here, we review the use of MSCs-related exosomes in tissues and organs. We also discuss their potential utility for treating rotator cuff injuries, and explore the underlying mechanisms of their effects.

Basic and Preclinical Research for Personalized Medicine

Basic and preclinical research founded the progress of personalized medicine by providing a prodigious amount of integrated profiling data and by enabling the development of biomedical applications to be implemented in patient-centered care and cures. If the rapid development of genomics research boosted the birth of personalized medicine, further development in omics technologies has more recently improved our understanding of the functional genome and its relevance in profiling patients’ phenotypes and disorders. Concurrently, the rapid biotechnological advancement in diverse research areas enabled uncovering disease mechanisms and prompted the design of innovative biological treatments tailored to individual patient genotypes and phenotypes. Research in stem cells enabled clarifying their role in tissue degeneration and disease pathogenesis while providing novel tools toward the development of personalized regenerative medicine strategies. Meanwhile, the evolving field of integrated omics technologies ensured translating structural genomics information into actionable knowledge to trace detailed patients’ molecular signatures. Finally, neuroscience research provided invaluable models to identify preclinical stages of brain diseases. This review aims at discussing relevant milestones in the scientific progress of basic and preclinical research areas that have considerably contributed to the personalized medicine revolution by bridging the bench-to-bed gap, focusing on stem cells, omics technologies, and neuroscience fields as paradigms.

Calcium channels and their role in regenerative medicine

Stem cells hold indefinite self-renewable capability that can be differentiated into all desired cell types. Based on their plasticity potential, they are divided into totipotent (morula stage cells), pluripotent (embryonic stem cells), multipotent (hematopoietic stem cells, multipotent adult progenitor stem cells, and mesenchymal stem cells [MSCs]), and unipotent (progenitor cells that differentiate into a single lineage) cells. Though bone marrow is the primary source of multipotent stem cells in adults, other tissues such as adipose tissues, placenta, amniotic fluid, umbilical cord blood, periodontal ligament, and dental pulp also harbor stem cells that can be used for regenerative therapy. In addition, induced pluripotent stem cells also exhibit fundamental properties of self-renewal and differentiation into specialized cells, and thus could be another source for regenerative medicine. Several diseases including neurodegenerative diseases, cardiovascular diseases, autoimmune diseases, virus infection (also coronavirus disease 2019) have limited success with conventional medicine, and stem cell transplantation is assumed to be the best therapy to treat these disorders. Importantly, MSCs, are by far the best for regenerative medicine due to their limited immune modulation and adequate tissue repair. Moreover, MSCs have the potential to migrate towards the damaged area, which is regulated by various factors and signaling processes. Recent studies have shown that extracellular calcium (Ca²⁺) promotes the proliferation of MSCs, and thus can assist in transplantation therapy. Ca²⁺ signaling is a highly adaptable intracellular signal that contains several components such as cell-surface receptors, Ca²⁺ channels/pumps/exchangers, Ca²⁺ buffers, and Ca²⁺ sensors, which together are essential for the appropriate functioning of stem cells and thus modulate their proliferative and regenerative capacity, which will be discussed in this review.

NAT10 Promotes Osteogenic Differentiation of Mesenchymal Stem Cells by Mediating N4-Acetylcytidine Modification of Gremlin 1

Objective

To investigate the function of NAT10 in mesenchymal stem cell (MSC) osteogenic differentiation and study the mechanism by which NAT10 affects MSC osteogenesis by mediating Gremlin 1 N4-acetylcytidine (ac⁴C) modification.

Methods

Osteogenic differentiation of MSCs was induced, and the osteogenic ability was evaluated with alizarin red S (ARS) and alkaline phosphatase (ALP) assays. The NAT10 expression level during MSC osteogenesis was measured by western blot (WB). MSCs were transfected with lentiviruses to inhibit (Sh-NAT10) or overexpress NAT10 (Over-NAT10), and the osteogenic differentiation ability was assessed by ARS, ALP, and osteogenic gene marker assays. β-Catenin, Akt, and Smad signaling pathway component activation levels were assessed, and the expression levels of key Smad signaling pathway molecules were determined by PCR and WB. The Gremlin 1 mRNA ac⁴C levels were analyzed using RIP-PCR, and the Gremlin 1 mRNA degradation rate was determined. Sh-Gremlin 1 was transfected to further investigate the role of NAT10 and Gremlin 1 in MSC osteogenesis.

Results

During MSC osteogenesis, NAT10 expression, ARS staining, and the ALP level gradually increased. Decreasing NAT10 expression inhibited, and increasing NAT10 expression promoted MSC osteogenic differentiation. NAT10 affected the BMP/Smad rather than the Akt and β-Catenin signaling pathway activation by regulating Gremlin 1 expression. The Gremlin 1 mRNA ac⁴C level was positively regulated by NAT10, which accelerated Gremlin 1 degradation. Sh-Gremlin 1 abolished the promotive effect of NAT10 on MSC osteogenic differentiation.

Conclusion

NAT10 positively regulated MSC osteogenic differentiation through accelerating the Gremlin 1 mRNA degradation by increasing its ac⁴C level. These results may provide new mechanistic insight into MSC osteogenesis and bone metabolism in vivo.

The role and mechanism of mitochondrial functions and energy metabolism in the function regulation of the mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent cells that show self-renewal, multi-directional differentiation, and paracrine and immune regulation. As a result of these properties, the MSCs have great clinical application prospects, especially in the regeneration of injured tissues, functional reconstruction, and cell therapy. However, the transplanted MSCs are prone to ageing and apoptosis and have a difficult to control direction differentiation. Therefore, it is necessary to effectively regulate the functions of the MSCs to promote their desired effects. In recent years, it has been found that mitochondria, the main organelles responsible for energy metabolism and adenosine triphosphate production in cells, play a key role in regulating different functions of the MSCs through various mechanisms. Thus, mitochondria could act as effective targets for regulating and promoting the functions of the MSCs. In this review, we discuss the research status and current understanding of the role and mechanism of mitochondrial energy metabolism, morphology, transfer modes, and dynamics on MSC functions.

Menaquinone-7 Supplementation Improves Osteogenesis in Pluripotent Stem Cell Derived Mesenchymal Stem Cells

Development of clinical stem cell interventions are hampered by immature cell progeny under current protocols. Human mesenchymal stem cells (hMSCs) are characterized by their ability to self-renew and differentiate into multiple lineages. Generating hMSCs from pluripotent stem cells (iPSCs) is an attractive avenue for cost-efficient and scalable production of cellular material. In this study we generate mature osteoblasts from iPSCs using a stable expandable MSC intermediate, refining established protocols. We investigated the timeframe and phenotype of cells under osteogenic conditions as well as the effect of menaquinone-7 (MK-7) on differentiation. From day 2 we noted a significant increase in RUNX2 expression under osteogenic conditions with MK-7, as well as decreases in ROS species production, increased cellular migration and changes to dynamics of collagen deposition when compared to differentiated cells that were not treated with MK-7. At day 21 OsteoMK-7 increased alkaline phosphatase activity and collagen deposition, as well as downregulated RUNX2 expression, suggesting to a mature cellular phenotype. Throughout we note no changes to expression of osteocalcin suggesting a non-canonical function of MK-7 in osteoblast differentiation. Together our data provide further mechanistic insight between basic and clinical studies on extrahepatic activity of MK-7. Our findings show that MK-7 promotes osteoblast maturation thereby increasing osteogenic differentiation.

Stem cell-based therapeutic strategies for corneal epithelium regeneration

Any significant loss of vision or blindness caused by corneal damages is referred to as corneal blindness. Corneal blindness is the fourth most common cause of blindness worldwide, representing more than 5% of the total blind population. Currently, corneal transplantation is used to treat many corneal diseases. In some cases, implantation of artificial cornea (keratoprosthesis) is suggested after a patient has had a donor corneal transplant failure. The shortage of donors and the side effects of keratoprosthesis are limiting these approaches. Recently, researchers have been actively pursuing new approaches for corneal regeneration because of these limitations. Nowadays, tissue engineering of different corneal layers (epithelium, stroma, endothelium, or full thickness tissue) is a promising approach that has attracted a great deal of interest from researchers and focuses on regenerative strategies using different cell sources and biomaterials. Various sources of corneal and non-corneal stem cells have shown significant advantages for corneal epithelium regeneration applications. Pluripotent stem cells (embryonic stem cells and iPS cells), epithelial stem cells (derived from oral mucus, amniotic membrane, epidermis and hair follicle), mesenchymal stem cells (bone marrow, adipose-derived, amniotic membrane, placenta, umbilical cord), and neural crest origin stem cells (dental pulp stem cells) are the most promising sources in this regard. These cells could also be used in combination with natural or synthetic scaffolds to improve the efficacy of the therapeutic approach. As the ocular surface is exposed to external damage, the number of studies on regeneration of the corneal epithelium is rising. In this paper, we reviewed the stem cell-based strategies for corneal epithelium regeneration.

Urine-derived stem/progenitor cells: A focus on their characterization and potential

Cell therapy, i.e., the use of cells to repair an affected tissue or organ, is at the forefront of regenerative and personalized medicine. Among the multiple cell types that have been used for this purpose [including adult stem cells such as mesenchymal stem cells or pluripotent stem cells], urine-derived stem cells (USCs) have aroused interest in the past years. USCs display classical features of mesenchymal stem cells such as differentiation capacity and immunomodulation. Importantly, they have the main advantage of being isolable from one sample of voided urine with a cheap and unpainful procedure, which is broadly applicable, whereas most adult stem cell types require invasive procedure. Moreover, USCs can be differentiated into renal cell types. This is of high interest for renal cell therapy-based regenerative approaches. This review will firstly describe the isolation and characterization of USCs. We will specifically present USC phenotype, which is not an object of consensus in the literature, as well as detail their differentiation capacity. In the second part of this review, we will present and discuss the main applications of USCs. These include use as a substrate to generate human induced pluripotent stem cells, but we will deeply focus on the use of USCs for cell therapy approaches with a detailed analysis depending on the targeted organ or system. Importantly, we will also focus on the applications that rely on the use of USC-derived products such as microvesicles including exosomes, which is a strategy being increasingly employed. In the last section, we will discuss the remaining barriers and challenges in the field of USC-based regenerative medicine.

Topography: A Biophysical Approach to Direct the Fate of Mesenchymal Stem Cells in Tissue Engineering Applications

Tissue engineering is a promising strategy to treat tissue and organ loss or damage caused by injury or disease. During the past two decades, mesenchymal stem cells (MSCs) have attracted a tremendous amount of interest in tissue engineering due to their multipotency and self-renewal ability. MSCs are also the most multipotent stem cells in the human adult body. However, the application of MSCs in tissue engineering is relatively limited because it is difficult to guide their differentiation toward a specific cell lineage by using traditional biochemical factors. Besides biochemical factors, the differentiation of MSCs also influenced by biophysical cues. To this end, much effort has been devoted to directing the cell lineage decisions of MSCs through adjusting the biophysical properties of biomaterials. The surface topography of the biomaterial-based scaffold can modulate the proliferation and differentiation of MSCs. Presently, the development of micro- and nano-fabrication techniques has made it possible to control the surface topography of the scaffold precisely. In this review, we highlight and discuss how the main topographical features (i.e., roughness, patterns, and porosity) are an efficient approach to control the fate of MSCs and the application of topography in tissue engineering.

Characterising Vascular Cell Monolayers Using Electrochemical Impedance Spectroscopy and a Novel Electroanalytical Plot

INTRODUCTION

Biological research relies on the culture of mammalian cells, which are prone to changes in phenotype during experiments involving several passages of cells. In regenerative medicine, specifically, there is an increasing need to expand the characterisation landscape for stem cells by identifying novel stable markers. This paper reports on a novel electric cell-substrate impedance sensing-based electroanalytical diagram which can be used for the "electrical characterisation" of cell monolayers consisting of smooth muscle cells, endothelial cells or co-culture.

MATERIALS AND METHODS

Interdigitated electrodes were microfabricated using standard cleanroom procedures and integrated into cell chambers. Electrochemical impedance spectroscopy data were acquired for 2 vascular cell types after they formed monolayers on the electrodes.

RESULTS AND DISCUSSION

A Mean impedance per unit area vs Mean phase plots provided a reproducible, visually obvious and statistically significant method of characterising cell monolayers. This electroanalytic diagram has never been used in previous papers, but it confirms findings by other research groups using similar approaches that the complex impedance spectra of different cell type are different. Further work is required to determine whether this method could be extended to other cell types, and if this is the case, a library of "signature spectra" could be generated for "electrical characterisation" of cells.

Mesenchymal stem cells in the fight against viruses: Face to face with the invisible enemy

The relative ease of isolation of mesenchymal stem cells (MSCs) from different tissues coupled with their culture expansion in vitro and their differentiation capacity to mesodermal, endodermal and ectodermal lineages have made these cells attractive for a large number of therapeutic applications. In recent years, there has been remarkable progress in the utilization of MSCs in diverse clinical indications both in animal models and human clinical trials. However, the potential of MSCs to control or treat viral diseases is still in its infancy. In this study, we report quantitative data on the MSC-based clinical trials over the last ten years as they appear on the online database of clinical research studies from US National Institutes of Health. In particular, we provide comprehensive review of either completed or ongoing clinical trials using MSCs for virus-associated diseases focusing on HIV, hepatitis B virus and COVID-19 virus.