Wnt signaling pathway inhibitor promotes mesenchymal stem cells differentiation into cardiac progenitor cells in vitro and improves cardiomyopathy in vivo

BACKGROUND

Cardiovascular diseases particularly myocardial infarction (MI) are the leading cause of mortality and morbidity around the globe. As cardiac tissue possesses very limited regeneration potential, therefore use of a potent small molecule, inhibitor Wnt production-4 (IWP-4) for stem cell differentiation into cardiomyocytes could be a promising approach for cardiac regeneration. Wnt pathway inhibitors may help stem cells in their fate determination towards cardiomyogenic lineage and provide better homing and survival of cells in vivo. Mesenchymal stem cells (MSCs) derived from the human umbilical cord have the potential to regenerate cardiac tissue, as they are easy to isolate and possess multilineage differentiation capability. IWP-4 may promote the differentiation of MSCs into the cardiac lineage.

AIM

To evaluate the cardiac differentiation ability of IWP-4 and its subsequent in vivo effects.

METHODS

Umbilical cord tissue of human origin was utilized to isolate the MSCs which were characterized by their morphology, immunophenotyping of surface markers specific to MSCs, as well as by tri-lineage differentiation capability. Cytotoxicity analysis was performed to identify the optimal concentration of IWP-4. MSCs were treated with 5 μM IWP-4 at two different time intervals. Differentiation of MSCs into cardiomyocytes was evaluated at DNA and protein levels. The MI rat model was developed. IWP-4 treated as well as untreated MSCs were implanted in the MI model, then the cardiac function was analyzed via echocardiography. MSCs were labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) dye for tracking, while the regeneration of infarcted myocardium was examined by histology and immunohistochemistry.

RESULTS

MSCs were isolated and characterized. Cytotoxicity analysis showed that IWP-4 was non-cytotoxic at 5 μM concentration. Cardiac specific gene and protein expression analyses exhibited more remarkable results in fourteen days treated group that was eventually selected for in vivo transplantation. Cardiac function was restored in the IWP-4 treated group in comparison to the MI group. Immunohistochemical analysis confirmed the homing of pre-differentiated MSCs that were labeled with DiI cell labeling dye. Histological analysis confirmed the significant reduction in fibrotic area, and improved left ventricular wall thickness in IWP-4 treated MSC group.

CONCLUSION

Treatment of MSCs with IWP-4 inhibits Wnt pathway and promotes cardiac differentiation. These pre-conditioned MSCs transplanted in vivo improved cardiac function by cell homing, survival, and differentiation at the infarcted region, increased left ventricular wall thickness, and reduced infarct size.

Zinc enhances the cell adhesion, migration, and self-renewal potential of human umbilical cord derived mesenchymal stem cells

BACKGROUND

Zinc (Zn) is the second most abundant trace element after Fe, present in the human body. It is frequently reported in association with cell growth and proliferation, and its deficiency is considered to be a major disease contributing factor.

AIM

To determine the effect of Zn on in vitro growth and proliferation of human umbilical cord (hUC)-derived mesenchymal stem cells (MSCs).

METHODS

hUC-MSCs were isolated from human umbilical cord tissue and characterized based on immunocytochemistry, immunophenotyping, and tri-lineage differentiation. The impact of Zn on cytotoxicity and proliferation was determined by MTT and Alamar blue assay. To determine the effect of Zn on population doubling time (PDT), hUC-MSCs were cultured in media with and without Zn for several passages. An in vitro scratch assay was performed to analyze the effect of Zn on the wound healing and migration capability of hUC-MSCs. A cell adhesion assay was used to test the surface adhesiveness of hUC-MSCs. Transcriptional analysis of genes involved in the cell cycle, proliferation, migration, and self-renewal of hUC-MSCs was performed by quantitative real-time polymerase chain reaction. The protein expression of Lin28, a pluripotency marker, was analyzed by immunocytochemistry.

RESULTS

Zn at lower concentrations enhanced the rate of proliferation but at higher concentrations (> 100 µM), showed concentration dependent cytotoxicity in hUC-MSCs. hUC-MSCs treated with Zn exhibited a significantly greater healing and migration rate compared to untreated cells. Zn also increased the cell adhesion rate, and colony forming efficiency (CFE). In addition, Zn upregulated the expression of genes involved in the cell cycle (CDC20, CDK1, CCNA2, CDCA2), proliferation (transforming growth factor β1, GDF5, hypoxia-inducible factor 1α), migration (CXCR4, VCAM1, VEGF-A), and self-renewal (OCT4, SOX2, NANOG) of hUC-MSCs. Expression of Lin28 protein was significantly increased in cells treated with Zn.

CONCLUSION

Our findings suggest that zinc enhances the proliferation rate of hUC-MSCs decreasing the PDT, and maintaining the CFE. Zn also enhances the cell adhesion, migration, and self-renewal of hUC-MSCs. These results highlight the essential role of Zn in cell growth and development.

Overexpression of OLIG2 and MYT1L Transcription Factors Enhance the Differentiation Potential of Human Mesenchymal Stem Cells into Oligodendrocytes

BACKGROUND

Demyelinating diseases represent a broad spectrum of disorders and are characterized by the loss of specialized glial cells (oligodendrocytes), which eventually leads to neuronal degeneration. Stem cell-based regenerative approaches provide therapeutic options to regenerate demyelination-induced neurodegeneration.

OBJECTIVES

The current study aims to explore the role of oligodendrocyte-specific transcription factors (OLIG2 and MYT1L) under suitable media composition to facilitate human umbilical-cord-derived mesenchymal stem cells (hUC-MSCs) differentiation toward oligodendrocyte for their potential use to treat demyelinating disorders.

METHODOLOGY

hUC-MSCs were isolated, cultured, and characterized based on their morphological and phenotypic characteristics. hUC-MSCs were transfected with OLIG2 and MYT1L transcription factors individually and in synergistic (OLIG2 + MYT1L) groups using a lipofectamine-based transfection method and incubated under two different media compositions (normal and oligo induction media). Transfected hUC-MSCs were assessed for lineage specification and differentiation using qPCR. Differentiation was also analyzed via immunocytochemistry by determining the expression of oligodendrocyte-specific proteins.

RESULTS

All the transfected groups showed significant upregulation of GFAP and OLIG2 with downregulation of NES, demonstrating the MSC commitment toward the glial lineage. Transfected groups also presented significant overexpression of oligodendrocyte-specific markers (SOX10, NKX2.2, GALC, CNP, CSPG4, MBP, and PLP1). Immunocytochemical analysis showed intense expression of OLIG2, MYT1L, and NG2 proteins in both normal and oligo induction media after 3 and 7 days.

CONCLUSIONS

The study concludes that OLIG2 and MYT1L have the potential to differentiate hUC-MSCs into oligodendrocyte-like cells, which is greatly facilitated by the oligo induction medium. The study may serve as a promising cell-based therapeutic strategy against demyelination-induced neuronal degeneration.

Osteochondral Tissue Engineering Dilemma: Scaffolding Trends in Regenerative Medicine

Orthopedic surgeons face a lot of difficulties in managing and repairing osteochondral defects. Damaged articular cartilage and the subchondral bone underneath are both present in osteochondral defects. The demands of the bone, cartilage, and the contact between the bone and the cartilage must be taken into consideration while repairing an osteochondral defect. Only palliative, not curative, therapeutic interventions are now available for the healing of osteochondral abnormalities. With its ability to successfully rebuild bone, cartilage, and the junction between bone and cartilage, tissue engineering has been recognized as an effective substitute. In correlation, mechanical stress and physical processes are commonly applied to the osteochondral area. Therefore, the ability of chondrocytes and osteoblasts to regenerate is influenced by bioactive molecules and the physicochemical characteristics of the surrounding matrix. The treatment of osteochondral disorders is said to benefit from the use of stem cells as an alternative intervention. In the field of tissue engineering, various approaches have been used such as the direct implantation of scaffolding materials at the site of tissue injury in patients, either alone or loaded with cells and bioactive molecules at the target site to imitate the natural extracellular matrix. Despite the extensive use and advancements of tissue-engineered biomaterials such as natural and synthetic polymer-based scaffolds, their repair capacity is limited due to challenges in combating antigenicity, designed to simulate in vivo microenvironment, and conducting mechanical or metabolic characteristics comparable to native organs/tissues. This study explores numerous osteochondral tissue engineering methodologies focusing on scaffold design, material varieties, manufacturing techniques, and functional features. This review is focused on recent breakthroughs in bioactive scaffolds that aid osteogenic and chondrogenic differentiation for bone and cartilage repair. The topic will cover fundamental anatomy, osteochondral repair methodologies and obstacles, cell selection, biochemical variables, and bioactive materials, as well as the design and manufacture of bioactive scaffolds. Additionally, we focus on the concept and construction of decellularized scaffolds, and the fabrication of dECM scaffolds in tissue engineering from various skin, bone, nerve, heart tissue, lung, liver, and kidney, and their application in osteochondral regeneration.

Co-regulation of Sox9 and TGFβ1 transcription factors in mesenchymal stem cells regenerated the intervertebral disc degeneration

Background

Intervertebral disc (IVD) shows aging and degenerative changes earlier than any other body connective tissue. Its repair and regeneration provide a considerable challenge in regenerative medicine due to its high degree of infrastructure and mechanical complexity. Mesenchymal stem cells, due to their tissue resurfacing potential, represent many explanatory pathways to regenerate a tissue breakdown.

Methods

This study was undertaken to evaluate the co-regulation of Sox9 and TGFβ1 in differentiating human umbilical cord mesenchymal stem cells (hUC-MSC) into chondrocytes. The combinatorial impact of Sox9 and TGFβ1 on hUC-MSCs was examined in vitro by gene expression and immunocytochemical staining. In in vivo, an animal model of IVD degeneration was established under a fluoroscopic guided system through needle puncture of the caudal disc. Normal and transfected MSCs were transplanted. Oxidative stress, pain, and inflammatory markers were evaluated by qPCR. Disc height index (DHI), water content, and gag content were analyzed. Histological examinations were performed to evaluate the degree of regeneration.

Results

hUC-MSC transfected with Sox9+TGFβ1 showed a noticeable morphological appearance of a chondrocyte, and highly expressed chondrogenic markers (aggrecan, Sox9, TGFβ1, TGFβ2, and type II collagens) after transfection. Histological observation demonstrated that cartilage regeneration, extracellular matrix synthesis, and collagen remodeling were significant upon staining with H&E, Alcian blue, and Masson's trichrome stain on day 14. Additionally, oxidative stress, pain, and inflammatory markers were positively downregulated in the animals transplanted with Sox9 and TGFβ1 transfected MSCs.

Conclusion

These findings indicate that the combinatorial effect of Sox9 and TGFβ1 substantially accelerates the chondrogenesis in hUC-MSCs. Cartilage regeneration and matrix synthesis were significantly enhanced. Therefore, a synergistic effect of Sox9 and TGFβ1 could be an immense therapeutic combination in the tissue engineering of cartilaginous joint bio-prostheses and a novel candidate for cartilage stabilization.

Role of quercetin and rutin in enhancing the therapeutic potential of mesenchymal stem cells for cold induced burn wound

Introduction

Cold burn wounds differ in their pathophysiological spectrum as compared to other types of burn wounds. These wounds have prolonged devastating effects on the body including hypertrophic scars, contracture, and necrosis. Mesenchymal stem cells (MSCs) are considered promising candidates for the complete regeneration of burn wounds. However, transplanted MSCs face the challenge to survive under the harsh tissue conditions. Preconditioning of MSCs with bioactive compounds may enhance their survival and regenerative potential for use in clinical applications. Bioactive compounds of Melia azedarach are well known for their potential role in treating different types of skin wounds due to their anti-inflammatory, anti-viral, anti-cytotoxic, and anti-oxidative properties. This study aims to evaluate the synergistic effects of human umbilical cord derived MSCs (hUC-MSCs) after preconditioning them with bioactive compounds of M. azedarach (quercetin and rutin) for cold induced burn wounds.

Method

Human umbilical cord MSCs (hUC-MSCs) were characterized based on their specific cell surface markers and treated with 20 μM of quercetin or rutin. In vitro scratch assay was performed to measure cell migration and wound closure. In vivo cold burn wound model was developed via direct exposure of the dorsal rat skin to liquid nitrogen. hUC-MSCs were subcutaneously transplanted next day of burn wound induction and wound was examined at different time points corresponding to the wound healing phases (days 3, 7, and 14). The regenerative potential of preconditioned hUC-MSCs was assessed in different groups; control (treated only with hUC-MSCs), and treated groups (quercetin or rutin treated hUC-MSCs). Healing potential and wound closure were evaluated by histological, gene expression, and immunohistochemical analyses of the wound tissues before and after treatment.

Results

Scratch assay exhibited enhanced cell migration towards wound closure in the treated groups as compared to the control. Macroscopic examination of the wound revealed scab formation at day 14 in control, whereas scab was detached and the wound tissue was remarkably remodeled in the treated groups. Comparison between the treated groups showed that burn wound treated with quercetin significantly increased healing potential than the rutin treated MSCs. Histological findings showed enhanced regeneration of skin layers along with hair follicles in the quercetin group, while increased neovascularization was noted in both treatment groups. Gene profile of wound healing mediators illustrated significant upregulation of IL-5, IL-4, GPX-7, TXNRD-2, PRDX, VEGF, and FGF and downregulation of inflammatory cytokines IL-1β and IL-6.

Conclusion

In conclusion, synergistic effect of hUC-MSCs and bioactive compounds of M. azedarach enhances wound healing by reducing the inflammation, mitigating oxidative stress and enhancing neovascularization. The study findings will aid in designing more effective treatment options for cold burn wounds.

Zinc and hypoxic preconditioning: a strategy to enhance the functionality and therapeutic potential of bone marrow-derived mesenchymal stem cells

The therapeutic use of bone marrow mesenchymal stem cells (BM-MSCs) requires a large number of cells (1-100 × 10⁶ cells/kg of body weight). Extensive in vitro growth is limited due to the aging of cultured BM-MSCs which leads to abnormal morphology and senescence. Hypoxia increases BM-MSC proliferation, but the question of whether hypoxia preconditioning is safe for clinical application of BM-MSCs remains to be answered. Zinc is essential for cell proliferation and differentiation, especially for the regulation of DNA synthesis and mitosis. It is a structural constituent of numerous proteins on a molecular level, including transcription factors and enzymes of cellular signaling machinery. All the tissues, fluids, and organs of the human body contain zinc. More than 95% of zinc is intracellular, of which 44% is involved in the transcription of DNA. We investigated the effects of ZnCl₂ on proliferation, morphology, migration, population doubling time (PDT), and gene expression of BM-MSCs under hypoxic (1% O₂) and normoxic (21% O₂) environments. BM-MSCs were preconditioned with optimized concentrations of ZnCl₂ under normoxic and hypoxic environments and further examined for morphology by the phase-contrast inverted microscope, cell proliferation by MTT assay, PDT, cell migration ability, and gene expression analysis. Zinc significantly enhanced the proliferation of BM-MSCs, and it decreases PDT under hypoxic and normoxic environments as compared to control cells. Migration of BM-MSCs toward the site of injury increased and expression of HIF1-α significantly decreased under hypoxic conditions as compared to non-treated hypoxic cells and control. At late passages (P₉), the morphology of normoxic BM-MSCs was transformed into large, wide, and flat cells, and they became polygonal and lost their communication with other cells. Conversely, zinc-preconditioned BM-MSCs retained their spindle-shaped, fibroblast-like morphology at P₉. The expression of proliferative genes was found significantly upregulated, while downregulation of genes OCT4 and CCNA2 was observed in zinc-treated BM-MSCs under both normoxic and hypoxic conditions. ZnCl₂ treatment can be used for extensive expansion of BM-MSCs in aged populations to obtain a large number of cells required for systemic administration to produce therapeutic efficacy.

Overexpression of GATA binding protein 4 and myocyte enhancer factor 2C induces differentiation of mesenchymal stem cells into cardiac-like cells

BACKGROUND

Heart diseases are the primary cause of death all over the world. Following myocardial infarction, billions of cells die, resulting in a huge loss of cardiac function. Stem cell-based therapies have appeared as a new area to support heart regeneration. The transcription factors GATA binding protein 4 (GATA-4) and myocyte enhancer factor 2C (MEF2C) are considered prominent factors in the development of the cardiovascular system.

AIM

To explore the potential of GATA-4 and MEF2C for the cardiac differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs).

METHODS

hUC-MSCs were characterized morphologically and immunologically by the presence of specific markers of MSCs via immunocytochemistry and flow cytometry, and by their potential to differentiate into osteocytes and adipocytes. hUC-MSCs were transfected with GATA-4, MEF2C, and their combination to direct the differentiation. Cardiac differentiation was confirmed by semiquantitative real-time polymerase chain reaction and immunocytochemistry.

RESULTS

hUC-MSCs expressed specific cell surface markers CD105, CD90, CD44, and vimentin but lack the expression of CD45. The transcription factors GATA-4 and MEF2C, and their combination induced differentiation in hUC-MSCs with significant expression of cardiac genes i.e., GATA-4, MEF2C, NK2 homeobox 5 (NKX2.5), MHC, and connexin-43, and cardiac proteins GATA-4, NKX2.5, cardiac troponin T, and connexin-43.

CONCLUSION

Transfection with GATA-4, MEF2C, and their combination effectively induces cardiac differentiation in hUC-MSCs. These genetically modified MSCs could be a promising treatment option for heart diseases in the future.

Combination of mesenchymal stem cells and three-dimensional collagen scaffold preserves ventricular remodeling in rat myocardial infarction model

BACKGROUND

Cardiovascular diseases are the major cause of mortality worldwide. Regeneration of the damaged myocardium remains a challenge due to mechanical constraints and limited healing ability of the adult heart tissue. Cardiac tissue engineering using biomaterial scaffolds combined with stem cells and bioactive molecules could be a highly promising approach for cardiac repair. Use of biomaterials can provide suitable microenvironment to the cells and can solve cell engraftment problems associated with cell transplantation alone. Mesenchymal stem cells (MSCs) are potential candidates in cardiac tissue engineering because of their multilineage differentiation potential and ease of isolation. Use of DNA methyl transferase inhibitor, such as zebularine, in combination with three-dimensional (3D) scaffold can promote efficient MSC differentiation into cardiac lineage, as epigenetic modifications play a fundamental role in determining cell fate and lineage specific gene expression.

AIM

To investigate the role of collagen scaffold and zebularine in the differentiation of rat bone marrow (BM)-MSCs and their subsequent in vivo effects.

METHODS

MSCs were isolated from rat BM and characterized morphologically, immunophenotypically and by multilineage differentiation potential. MSCs were seeded in collagen scaffold and treated with 3 μmol/L zebularine in three different ways. Cytotoxicity analysis was done and cardiac differentiation was analyzed at the gene and protein levels. Treated and untreated MSC-seeded scaffolds were transplanted in the rat myocardial infarction (MI) model and cardiac function was assessed by echocardiography. Cell tracking was performed by DiI dye labeling, while regeneration and neovascularization were evaluated by histological and immunohistochemical analysis, respectively.

RESULTS

MSCs were successfully isolated and seeded in collagen scaffold. Cytotoxicity analysis revealed that zebularine was not cytotoxic in any of the treatment groups. Cardiac differentiation analysis showed more pronounced results in the type 3 treatment group which was subsequently chosen for the transplantation in the in vivo MI model. Significant improvement in cardiac function was observed in the zebularine treated MSC-seeded scaffold group as compared to the MI control. Histological analysis also showed reduction in fibrotic scar, improvement in left ventricular wall thickness and preservation of ventricular remodeling in the zebularine treated MSC-seeded scaffold group. Immunohistochemical analysis revealed significant expression of cardiac proteins in DiI labeled transplanted cells and a significant increase in the number of blood vessels in the zebularine treated MSC-seeded collagen scaffold transplanted group.

CONCLUSION

Combination of 3D collagen scaffold and zebularine treatment enhances cardiac differentiation potential of MSCs, improves cell engraftment at the infarcted region, reduces infarct size and improves cardiac function.

Decellularized Human Umbilical Tissue-Derived Hydrogels Promote Proliferation and Chondrogenic Differentiation of Mesenchymal Stem Cells

Tissue engineering is a promising approach for the repair and regeneration of cartilaginous tissue. Appropriate three-dimensional scaffolding materials that mimic cartilage are ideal for the repair of chondral defects. The emerging decellularized tissue-based scaffolds have the potential to provide essential biochemical signals and structural integrity, which mimics the natural tissue environment and directs cellular fate. Umbilical cord-derived hydrogels function as 3D scaffolding material, which support adherence, proliferation, migration, and differentiation of cells due to their similar biochemical composition to cartilage. Therefore, the present study aimed to establish a protocol for the formulation of a hydrogel from decellularized human umbilical cord (DUC) tissue, and assess its application in the proliferation and differentiation of UC-MSCs along chondrogenic lineage. The results showed that the umbilical cord was efficiently decellularized. Subsequently, DUC hydrogel was prepared, and in vitro chondral differentiation of MSCs seeded on the scaffold was determined. The developed protocol efficiently removed the cellular and nuclear content while retaining the extracellular matrix (ECM). DUC tissue, pre-gel, and hydrogels were evaluated by FTIR spectroscopy, which confirmed the gelation from pre-gel to hydrogel. SEM analysis revealed the fibril morphology and porosity of the DUC hydrogel. Calcein AM and Alamar blue assays confirmed the MSC survival, attachment, and proliferation in the DUC hydrogels. Following seeding of UC-MSCs in the hydrogels, they were cultured in stromal or chondrogenic media for 28 days, and the expression of chondrogenic marker genes including TGF-β1, BMP2, SOX-9, SIX-1, GDF-5, and AGGRECAN was significantly increased (* p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001). Moreover, the hydrogel concentration was found to significantly affect the expression of chondrogenic marker genes. The overall results indicate that the DUC-hydrogel is compatible with MSCs and supports their chondrogenic differentiation in vitro.

Transcription regulators differentiate mesenchymal stem cells into chondroprogenitors, and their in vivo implantation regenerated the intervertebral disc degeneration

BACKGROUND

Intervertebral disc degeneration (IVDD) is the leading cause of lower back pain. Disc degeneration is characterized by reduced cellularity and decreased production of extracellular matrix (ECM). Mesenchymal stem cells (MSCs) have been envisioned as a promising treatment for degenerative illnesses. Cell-based therapy using ECM-producing chondrogenic derivatives of MSCs has the potential to restore the functionality of the intervertebral disc (IVD).

AIM

To investigate the potential of chondrogenic transcription factors to promote differentiation of human umbilical cord MSCs into chondrocytes, and to assess their therapeutic potential in IVD regeneration.

METHODS

MSCs were isolated and characterized morphologically and immunologically by the expression of specific markers. MSCs were then transfected with Sox-9 and Six-1 transcription factors to direct differentiation and were assessed for chondrogenic lineage based on the expression of specific markers. These differentiated MSCs were implanted in the rat model of IVDD. The regenerative potential of transplanted cells was investigated using histochemical and molecular analyses of IVDs.

RESULTS

Isolated cells showed fibroblast-like morphology and expressed CD105, CD90, CD73, CD29, and Vimentin but not CD45 antigens. Overexpression of Sox-9 and Six-1 greatly enhanced the gene expression of transforming growth factor beta-1 gene, BMP, Sox-9, Six-1, and Aggrecan, and protein expression of Sox-9 and Six-1. The implanted cells integrated, survived, and homed in the degenerated intervertebral disc. Histological grading showed that the transfected MSCs regenerated the IVD and restored normal architecture.

CONCLUSION

Genetically modified MSCs accelerate cartilage regeneration, providing a unique opportunity and impetus for stem cell-based therapeutic approach for degenerative disc diseases.

Regulating the fate of stem cells for regenerating the intervertebral disc degeneration

Lower back pain is a leading cause of disability and is one of the reasons for the substantial socioeconomic burden. The etiology of intervertebral disc (IVD) degeneration is complicated, and its mechanism is still not completely understood. Factors such as aging, systemic inflammation, biochemical mediators, toxic environmental factors, physical injuries, and genetic factors are involved in the progression of its pathophysiology. Currently, no therapy for restoring degenerated IVD is available except pain management, reduced physical activities, and surgical intervention. Therefore, it is imperative to establish regenerative medicine-based approaches to heal and repair the injured disc, repopulate the cell types to retain water content, synthesize extracellular matrix, and strengthen the disc to restore normal spine flexion. Cellular therapy has gained attention for IVD management as an alternative therapeutic option. In this review, we present an overview of the anatomical and molecular structure and the surrounding pathophysiology of the IVD. Modern therapeutic approaches, including proteins and growth factors, cellular and gene therapy, and cell fate regulators are reviewed. Similarly, small molecules that modulate the fate of stem cells for their differentiation into chondrocytes and notochordal cell types are highlighted.

Effect of glycyrrhizic acid and 18β-glycyrrhetinic acid on the differentiation of human umbilical cord-mesenchymal stem cells into hepatocytes

BACKGROUND

End-stage liver disease is a global health complication with high prevalence and limited treatment options. Cell-based therapies using mesenchymal stem cells (MSCs) emerged as an alternative approach to support hepatic regeneration. In vitro preconditioning strategies have been employed to strengthen the regenerative and differentiation potential of MSCs towards hepatic lineage. Chemical compounds of the triterpene class; glycyrrhizic acid (GA) and 18β-glycyrrhetinic acid (GT) possess diverse therapeutic properties including hepato-protection and anti-fibrosis characteristics. They are capable of modulating several signaling pathways that are crucial in hepatic regeneration. Preconditioning with hepato-protective triterpenes may stimulate MSC fate transition towards hepatocytes.

AIM

To explore the effect of GA and GT on hepatic differentiation of human umbilical cord-MSCs (hUC-MSCs).

METHODS

hUC-MSCs were isolated and characterized phenotypically by flow cytometry and immunocytochemistry for the expression of MSC-associated surface molecules. Isolated cells were treated with GA, GT, and their combination for 24 h and then analyzed at three time points; day 7, 14, and 21. qRT-PCR was performed for the expression of hepatic genes. Expression of hepatic proteins was analyzed by immunocytochemistry at day 21. Periodic acid Schiff staining was performed to determine the functional ability of treated cells.

RESULTS

The fusiform-shaped morphology of MSCs in the treatment groups in comparison with the untreated control, eventually progressed towards the polygonal morphology of hepatocytes with the passage of time. The temporal transcriptional profile of preconditioned MSCs displayed significant expression of hepatic genes with increasing time of differentiation. Preconditioned cells showed positive expression of hepatocyte-specific proteins. The results were further corroborated by positive periodic acid Schiff staining, indicating the presence of glycogen in their cytoplasm. Moreover, bi-nucleated cells, which is the typical feature of hepatocytes, were also seen in the preconditioned cells.

CONCLUSION

Preconditioning with glycyrrhizic acid, 18β-glycyrrhetinic acid and their combination, successfully differentiates hUC-MSCs into hepatic-like cells. These MSCs may serve as a better therapeutic option for degenerative liver diseases in future.

Human umbilical cord-derived mesenchymal stem cells and their chondroprogenitor derivatives reduced pain and inflammation signaling and promote regeneration in a rat intervertebral disc degeneration model

Intervertebral disc (IVD) degeneration is an asymptomatic pathophysiological condition and a strong causative factor of low back pain. There is no cure available except spinal fusion and pain management. Stem cell-based regenerative medicine is being considered as an alternative approach to treat disc diseases. The current study aimed to differentiate human umbilical cord-mesenchymal stem cells (hUC-MSCs) into chondrocyte-like cells and to elucidate their feasibility and efficacy in the degenerated IVD rat model. Chondrogenic induction medium was used to differentiate hUC-MSCs into chondroprogenitors. Rat tail IVD model was established with three consecutive coccygeal discs. qPCR was performed to quantify the molecular markers of pain and inflammation. Histological staining was performed to evaluate the degree of regeneration. Induced chondroprogenitors showed the expression of chondrogenic genes, SOX9, TGF-β1, ACAN, BMP2, and GDF5. Immunocytochemical staining showed positive expression of chondrogenic proteins SOX9, TGF-β1, TGF-β2, and Collagen 2. In in vivo study, transplanted chondroprogenitors showed better survival, homing, and distribution in IVD as compared to normal MSCs. Expression of pain and inflammatory genes at day 5 of cell transplantation modulated immune response significantly. The transplanted labeled MSCs and induced chondroprogenitors differentiated into functional nucleus pulposus (NP) cells as evident from co-localization of red (DiI) and green fluorescence for SOX9, TGF-β1, and TGF-β2. Alcian blue and H & E staining showed standard histological features, indicating better preservation of the NP structure and cellularity than degenerated discs. hUC-MSCs-derived chondroprogenitors showed better regeneration potential as compared to normal MSCs. The pain and inflammation genes were downregulated in the treated group as compared to the degenerated IVD.

Umbilical cord-derived mesenchymal stem cells preconditioned with isorhamnetin: potential therapy for burn wounds

BACKGROUND

Impaired wound healing can be associated with different pathological states. Burn wounds are the most common and detrimental injuries and remain a major health issue worldwide. Mesenchymal stem cells (MSCs) possess the ability to regenerate tissues by secreting factors involved in promoting cell migration, proliferation and differentiation, while suppressing immune reactions. Preconditioning of MSCs with small molecules having cytoprotective properties can enhance the potential of these cells for their use in cell-based therapeutics.

AIM

To enhance the therapeutic potential of MSCs by preconditioning them with isorhamnetin for second degree burn wounds in rats.

METHODS

Human umbilical cord MSCs (hU-MSCs) were isolated and characterized by surface markers, CD105, vimentin and CD90. For preconditioning, hU-MSCs were treated with isorhamnetin after selection of the optimized concentration (5 µmol/L) by cytotoxicity analysis. The migration potential of these MSCs was analyzed by the in vitro scratch assay. The healing potential of normal, and preconditioned hU-MSCs was compared by transplanting these MSCs in a rat model of a second degree burn wound. Normal, and preconditioned MSCs (IH + MSCs) were transplanted after 72 h of burn injury and observed for 2 wk. Histological and gene expression analyses were performed on day 7 and 14 after cell transplantation to determine complete wound healing.

RESULTS

The scratch assay analysis showed a significant reduction in the scratch area in the case of IH + MSCs compared to the normal untreated MSCs at 24 h, while complete closure of the scratch area was observed at 48 h. Histological analysis showed reduced inflammation, completely remodeled epidermis and dermis without scar formation and regeneration of hair follicles in the group that received IH + MSCs. Gene expression analysis was time dependent and more pronounced in the case of IH + MSCs. Interleukin (IL)-1β, IL-6 and Bcl-2 associated X genes showed significant downregulation, while transforming growth factor β, vascular endothelial growth factor, Bcl-2 and matrix metallopeptidase 9 showed significant upregulation compared to the burn wound, showing increased angiogenesis and reduced inflammation and apoptosis.

CONCLUSION

Preconditioning of hU-MSCs with isorhamnetin decreases wound progression by reducing inflammation, and improving tissue architecture and wound healing. The study outcome is expected to lead to an improved cell-based therapeutic approach for burn wounds.

Small molecule 2'-deoxycytidine differentiates human umbilical cord-derived MSCs into cardiac progenitors in vitro and their in vivo xeno-transplantation improves cardiac function

Small molecules are widely used to induce stem cell differentiation. 2'-deoxycytidine (2-DC) belongs to the cytidine family. It stimulates the expression of cardiac-specific genes and proteins, and directs mesenchymal stem cells towards cardiomyogenic differentiation. We aim to investigate the role of 2-DC-treated human umbilical cord mesenchymal stem cells (UC-MSCs) into myogenic lineage and explore their application in regeneration of infarcted myocardium. UC-MSCs were treated with 5, 10, 20, and 40 µM 2-DC following optimization by cytotoxicity analysis. Rat model of myocardial infarction (MI) was induced by ligating left anterior descending coronary artery. Normal, and 2-DC treated UC-MSCs were transplanted in the left ventricular wall immediately after ligation. Echocardiographic measurements were performed to assess cardiac function. Tissue architecture of the myocardium was examined by histological analysis to determine fate of the transplanted cells. MSCs were successfully isolated from human umbilical cord tissue. 2-DC treatment did not produce any significant cytotoxic effect in UC-MSCs at all concentrations. qPCR analysis of treated UC-MSCs showed induction of myogenic differentiation, which is more pronounced at 20 μM concentration. Fluorescently labeled 2-DC-treated UC-MSCs showed significant (**P < 0.01) homing in the infarcted myocardium as compared to normal UC-MSCs. Hearts transplanted with 2-DC-treated UC-MSCs significantly (***P < 0.001) improved the cardiac systolic and diastolic functions and pumping ability as compared to normal UC-MSCs and MI groups. Fibrotic area and left ventricular wall thickness were significantly improved (***P < 0.001) in 2-DC-treated group as compared to normal UC-MSCs. Immunohistochemical staining showed co-localization of fluorescently labeled cells and patches of differentiated myocytes which were stained for cardiac proteins in the infarct zone implying that the treated UC-MSCs regenerated cardiomyocytes. We report for the first time that 2-DC induces cardiac differentiation in UC-MSCs. Transplanted cells differentiated into functional cardiomyocytes and significantly improved cardiac performance. These pre-differentiated cardiac progenitors showed better survival, homing, and distribution in the infarcted zone. 2-DC treated cells not only improved cardiac function, but also restored tissue homeostasis, suggesting a better therapeutic option for the regeneration of cardiac tissue in the clinical setup.

Epac-Rap1-activated mesenchymal stem cells improve cardiac function in rat model of myocardial infarction

INTRODUCTION

Rap1, a member of Ras superfamily of small GTP-binding proteins, is involved in cardiovascular biology in numerous ways. It is an evolutionary conserved regulator of adhesion, polarity, differentiation and growth.

AIMS

Our aim was to analyze Rap1-activated rat bone marrow mesenchymal stem cells (MSCs) for their potential role in adhesion and cardiac differentiation.

METHODS

Myocardial infarction (MI) was produced in Sprague Dawley (SD) rats through occlusion of the left anterior descending coronary artery. MSCs were treated with 8-pCPT-2'-O-Me-cAMP (CPT) to activate Rap1. Normal (untreated) and CPT-treated MSCs were transplanted through intramyocardial injection in respective groups. Cardiac function was assessed by echocardiography at 2 and 4 weeks after cell transplantation. Histological analysis was performed to observe changes at tissue level.

RESULTS

Homing of CPT-treated MSCs was significantly (***P<.001) higher as compared to normal MSCs in the infarcted hearts. This may be due to increase in the gene expression of some of the cell adhesion molecules as evident by qRT-PCR analysis. Significant (***P<.001) improvement in the restoration of heart function in terms of left ventricular diastolic and systolic internal diameters (LVIDd, LVIDs), % ejection fraction, % fraction shortening and end-systolic and end-diastolic volumes were observed in CPT-treated MSCs as compared to the MI model. Histological analyses showed significant (***P<.001) reduction in scar formation in the CPT-treated group. Differentiation of treated MSCs into functional cardiomyocytes was evident through immunohistochemical staining. LV wall thickness was also preserved significantly (***P<.001). Blood vessel formation was more pronounced in CPT-treated group although both cell therapy groups showed significant increase as compared to MI model.

CONCLUSION

Our findings showed that pharmacological activation of Epac-Rap1 improves cardiac function through better survival, adhesion and differentiation of transplanted cells. Transplantation of these MSCs in the infarct area restored functional myocardium.

BET protein inhibitor JQ1 inhibits growth and modulates WNT signaling in mesenchymal stem cells

BACKGROUND

Efficacy and safety of anticancer drugs are traditionally studied using cancer cell lines and animal models. The thienodiazepine class of BET inhibitors, such as JQ1, has been extensively studied for the potential treatment of hematological malignancies and several small molecules belonging to this class are currently under clinical investigation. While these compounds are well known to inhibit cancer cell growth and cause apoptosis, their effects on stem cells, particularly mesenchymal stem cells (MSCs), which are important for regeneration of damaged cells and tissues, are unknown. In this study we employed umbilical cord derived MSCs as a model system to evaluate the safety of JQ1.

METHODS

Cord derived MSCs were treated with various doses of JQ1 and subjected to cell metabolic activity, apoptosis, and cell cycle analyses using MTT assay, Annexin-V/FITC and PI staining, and flow cytometry, respectively. The effect of JQ1 on gene expression was determined using microarray and quantitative real-time reverse transcriptase polymerase chain reaction analysis. Furthermore, protein expression of apoptotic and neuronal markers was carried out using western blot and immunostaining, respectively.

RESULTS

Our results showed that JQ1 inhibited cell growth and caused cell cycle arrest in G1 phase but did not induce apoptosis or senescence. JQ1 also down-regulated genes involved in self-renewal, cell cycle, DNA replication, and mitosis, which may have negative implications on the regenerative potential of MSCs. In addition, JQ1 interfered with signaling pathways by down regulating the expression of WNT, resulting in limiting the self-renewal. These results suggest that anticancer agents belonging to the thienodiazepine class of BET inhibitors should be carefully evaluated before their use in cancer therapy.

CONCLUSIONS

This study revealed for the first time that JQ1 adversely affected MSCs, which are important for repair and regeneration. JQ1 specifically modulated signal transduction and inhibited growth as well as self-renewal. These findings suggest that perinatal MSCs could be used to supplement animal models for investigating the safety of anticancer agents and other drugs.