3D bio scaffold support osteogenic differentiation of mesenchymal stem cells

The regeneration of osteochondral lesions by tissue engineering techniques is challenging due to the lack of physicochemical characteristics and dual-lineage (osteogenesis and chondrogenesis). A scaffold with better mechanical properties and dual lineage capability is required for the regeneration of osteochondral defects. In this study, a hydrogel prepared from decellularized human umbilical cord tissue was developed and evaluated for osteochondral regeneration. Mesenchymal stem cells (MSCs) isolated from the umbilical cord were seeded with hydrogel for 28 days, and cell-hydrogel composites were cultured in basal and osteogenic media. Alizarin red staining, quantitative polymerase chain reaction, and immunofluorescent staining were used to confirm that the hydrogel was biocompatible and capable of inducing osteogenic differentiation in umbilical cord-derived MSCs. The findings demonstrate that human MSCs differentiated into an osteogenic lineage following 28 days of cultivation in basal and osteoinductive media. The expression was higher in the cell-hydrogel composites cultured in osteoinductive media, as evidenced by increased levels of messenger RNA and protein expression of osteogenic markers as compared to basal media cultured cell-hydrogel composites. Additionally, calcium deposits were also observed, which provide additional evidence of osteogenic differentiation. The findings demonstrate that the hydrogel is biocompatible with MSCs and possesses osteoinductive capability in vitro. It may be potentially useful for osteochondral regeneration.

Expansion of human umbilical cord derived mesenchymal stem cells in regenerative medicine

BACKGROUND

Stem cells are undifferentiated cells that possess the potential for self-renewal with the capacity to differentiate into multiple lineages. In humans, their limited numbers pose a challenge in fulfilling the necessary demands for the regeneration and repair of damaged tissues or organs. Studies suggested that mesenchymal stem cells (MSCs), necessary for repair and regeneration via transplantation, require doses ranging from 10 to 400 million cells. Furthermore, the limited expansion of MSCs restricts their therapeutic application.

AIM

To optimize a novel protocol to achieve qualitative and quantitative expansion of MSCs to reach the targeted number of cells for cellular transplantation and minimize the limitations in stem cell therapy protocols.

METHODS

Human umbilical cord (hUC) tissue derived MSCs were obtained and re-cultured. These cultured cells were subjected to the following evaluation procedures: Immunophenotyping, immunocytochemical staining, trilineage differentiation, population doubling time and number, gene expression markers for proliferation, cell cycle progression, senescence-associated β-galactosidase assay, human telomerase reverse transcriptase (hTERT) expression, mycoplasma, cytomegalovirus and endotoxin detection.

RESULTS

Analysis of pluripotent gene markers Oct4, Sox2, and Nanog in recultured hUC-MSC revealed no significant differences. The immunophenotypic markers CD90, CD73, CD105, CD44, vimentin, CD29, Stro-1, and Lin28 were positively expressed by these recultured expanded MSCs, and were found negative for CD34, CD11b, CD19, CD45, and HLA-DR. The recultured hUC-MSC population continued to expand through passage 15. Proliferative gene expression of Pax6, BMP2, and TGFb1 showed no significant variation between recultured hUC-MSC groups. Nevertheless, a significant increase (P < 0.001) in the mitotic phase of the cell cycle was observed in recultured hUC-MSCs. Cellular senescence markers (hTERT expression and β-galactosidase activity) did not show any negative effect on recultured hUC-MSCs. Additionally, quality control assessments consistently confirmed the absence of mycoplasma, cytomegalovirus, and endotoxin contamination.

CONCLUSION

This study proposes the development of a novel protocol for efficiently expanding stem cell population. This would address the growing demand for larger stem cell doses needed for cellular transplantation and will significantly improve the feasibility of stem cell based therapies.

Single dose human perinatal stem cells accelerate healing of cold-induced rat burn wound

Temporal phases of wound healing and their corresponding healing factors are essential in wound regeneration. Mesenchymal stem cells (MSCs) accelerate wound healing via their paracrine secretions by enhancing cell migration, angiogenesis, and reducing inflammation. This study evaluated the local therapeutic effect of human umbilical cord MSCs (hUCMSCs) in the healing of cold-induced burn wounds. An in vitro wound (scratch) was developed in rat skin fibroblasts. The culture was maintained in the conditioned medium (CM) which was prepared by inducing an artificial wound in hUCMSCs in a separate experiment. Treated fibroblasts were analyzed for the gene expression profile of healing mediators involved in wound closure. Findings revealed enhanced cell migration and increased levels of healing mediators in the treated fibroblasts relative to the untreated group. Cold-induced burn wounds were developed in Wistar rats, followed by a single injection of hUCMSCs. Wound healing pattern was examined based on the healing phases: hemostasis/inflammation (Days 1, 3), cell proliferation (Day 7), and remodeling (Day 14). Findings exhibited enhanced wound closure in the treated wound. Gene expression, histological, and immunohistochemical analyses further confirmed enhanced wound regeneration after hUCMSC transplantation. Temporal gene expression profile revealed that the level of corresponding cytokines was substantially increased in the treated wound as compared with the control, indicating improvement in the processes of angiogenesis and remodeling, and a substantial reduction in inflammation. Histology revealed significant collagen formation along with regenerated skin layers and appendages, whereas immunohistochemistry exhibited increased neovascularization during remodeling. Leukocyte infiltration was also suppressed in the treated group. Overall findings demonstrate that a single dose of hUCMSCs enhances wound healing in vivo, and their secreted growth factors accelerate cell migration in vitro.

Temporal and differential proteomic profile of molecular mediators associated with chronic and acute wound healing

The underlying pathophysiology of nonhealing chronic wounds is poorly understood due to the changes occurring at the gene level and the complexity arising in their proteomic profile. Here, we elucidated the temporal and differential profile of the normal and diabetic wound-healing mediators along with their interactions and associated pathways. Skin tissues corresponding to normal and diabetic wounds were isolated at Days 0, 3, 6, and 9 representing different healing phases. Temporal gene expression was analyzed by quantitative real-time PCR. Concurrently, differential protein patterns in the wound tissues were identified by Nano LC-ESI-TOF mass spectrometry and later confirmed by Western blot analysis. Gene ontology annotation, protein-protein interaction, and protein pathway analysis were performed using DAVID, PANTHER, and STRING bioinformatics resources. Uniquely identified proteins (complement C3, amyloid beta precursor protein, and cytoplasmic linker associated protein 2) in the diabetic wound tissue implied that these proteins are involved in the pathogenesis of diabetic wound. They exhibit enhanced catalytic activity, trigger pathways linked with inflammation, and negatively regulate wound healing. However, in the normal wound tissue, axin 1, chondroitin sulfate proteoglycan 4, and sphingosine-1-phosphate receptor were identified, which are involved in proliferation, angiogenesis, and remodeling. Our findings demonstrate the correlation between elevated gene expression of tumor necrosis factor-α, interleukin (IL)-1β, and identified mediators: aryl hydrocarbon receptor nuclear translocator, 5'-aminolevulinate synthase 2, and CXC-family, that inflicted an inflammatory response by activating downstream MAPK, JAK-STAT, and NF-κB pathways. Similarly, in normal wound tissue, the upregulated IL-4 and hepatocyte growth factor levels in conjunction with the identified proteins, serine/threonine-protein kinase mTOR and peroxisome proliferator-activated receptor gamma, played a significant role in the cellular response to platelet-derived growth factor stimulus, dermal epithelialization, and cell proliferation, processes associated with the repair mechanism. Furthermore, Western blot analysis indicated elevated levels of inflammatory markers and reduced levels of proliferative and angiogenic factors in the diabetic wound.

Assessment of the proteome profile of decellularized human amniotic membrane and its biocompatibility with umbilical cord-derived mesenchymal stem cells

Extracellular matrix-based bio-scaffolds are useful for tissue engineering as they retain the unique structural, mechanical, and physiological microenvironment of the tissue thus facilitating cellular attachment and matrix activities. However, considering its potential, a comprehensive understanding of the protein profile remains elusive. Herein, we evaluate the impact of decellularization on the human amniotic membrane (hAM) based on its proteome profile, physicochemical features, as well as the attachment, viability, and proliferation of umbilical cord-derived mesenchymal stem cells (hUC-MSC). Proteome profiles of decellularized hAM (D-hAM) were compared with hAM, and gene ontology (GO) enrichment analysis was performed. Proteomic data revealed that D-hAM retained a total of 249 proteins, predominantly comprised of extracellular matrix proteins including collagens (collagen I, collagen IV, collagen VI, collagen VII, and collagen XII), proteoglycans (biglycan, decorin, lumican, mimecan, and versican), glycoproteins (dermatopontin, fibrinogen, fibrillin, laminin, and vitronectin), and growth factors including transforming growth factor beta (TGF-β) and fibroblast growth factor (FGF) while eliminated most of the intracellular proteins. Scanning electron microscopy was used to analyze the epithelial and basal surfaces of D-hAM. The D-hAM displayed variability in fibril morphology and porosity as compared with hAM, showing loosely packed collagen fibers and prominent large pore areas on the basal side of D-hAM. Both sides of D-hAM supported the growth and proliferation of hUC-MSC. Comparative investigations, however, demonstrated that the basal side of D-hAM displayed higher hUC-MSC proliferation than the epithelial side. These findings highlight the importance of understanding the micro-environmental differences between the two sides of D-hAM while optimizing cell-based therapeutic applications.

Direct differentiation of rat skin fibroblasts into cardiomyocytes

Myocardial infarction (MI) is one of the major cardiovascular diseases caused by diminished supply of nutrients and oxygen to the heart due to obstruction of the coronary artery. Different treatment options are available for cardiac diseases, however, they do not completely repair the damage. Therefore, reprogramming terminally differentiated fibroblasts using transcription factors is a promising strategy to differentiate them into cardiac like cells in vitro and to increase functional cardiomyocytes and reduce fibrotic scar in vivo. In this study, skin fibroblasts were selected for reprogramming because they serve as a convenient source for the autologous cell therapy. Fibroblasts were isolated from skin of rat pups, propagated, and directly reprogrammed towards cardiac lineage. For reprogramming, two different approaches were adopted, i.e., cells were transfected with: (1) combination of cardiac transcription factors; GATA4, MEF2c, Nkx2.5 (GMN), and (2) combination of cardiac transcription factors; GATA4, MEF2c, Nkx2.5, and iPSC factors; Oct4, Klf4, Sox2 and cMyc (GMNO). After 72 h of transfection, cells were analyzed for the expression of cardiac markers at the mRNA and protein levels. For in vivo study, rat MI models were developed by ligating the left anterior descending coronary artery and the reprogrammed cells were transplanted in the infarcted heart. qPCR results showed that the reprogrammed cells exhibited significant upregulation of cardiac genes. Immunocytochemistry analysis further confirmed cardiomyogenic differentiation of the reprogrammed cells. For the assessment of cardiac function, animals were analyzed via echocardiography after 2 and 4 weeks of cell transplantation. Echocardiographic results showed that the hearts transplanted with the reprogrammed cells improved ejection fraction, fractional shortening, left ventricular internal systolic and diastolic dimensions, and end systolic and diastolic volumes. After 4 weeks of cell transplantation, heart tissues were harvested and processed for histology. The histological analysis showed that the reprogrammed cells improved wall thickness of left ventricle and reduced fibrosis significantly as compared to the control. It is concluded from the study that novel combination of cardiac transcription factors directly reprogrammed skin fibroblasts and differentiated them into cardiomyocytes. These differentiated cells showed cardiomyogenic characters in vitro, and reduced fibrosis and improved cardiac function in vivo. Furthermore, direct reprogramming of fibroblasts transfected with cardiac transcription factors showed better regeneration of the injured myocardium and improved cardiac function as compared to the indirect approach in which combination of cardiac and iPSC factors were used. The study after further optimization could be used as a better strategy for cell-based therapeutic approaches for cardiovascular diseases.

Mesenchymal Stem Cell-Derived Exosomes and Their MicroRNAs in Heart Repair and Regeneration

Mesenchymal stem cells (MSCs) can be differentiated into cardiac, endothelial, and smooth muscle cells. Therefore, MSC-based therapeutic approaches have the potential to deal with the aftermaths of cardiac diseases. However, transplanted stem cells rarely survive in damaged myocardium, proposing that paracrine factors other than trans-differentiation may involve in heart regeneration. Apart from cytokines/growth factors, MSCs secret small, single-membrane organelles named exosomes. The MSC-secreted exosomes are enriched in lipids, proteins, nucleic acids, and microRNA (miRNA). There has been an increasing amount of data that confirmed that MSC-derived exosomes and their active molecule microRNA (miRNAs) regulate signaling pathways involved in heart repair/regeneration. In this review, we systematically present an overview of MSCs, their cardiac differentiation, and the role of MSC-derived exosomes and exosomal miRNAs in heart regeneration. In addition, biological functions regulated by MSC-derived exosomes and exosomal-derived miRNAs in the process of heart regeneration are reviewed.

Effect of lawsone-preconditioned mesenchymal stem cells on the regeneration of pancreatic β cells in Type 1 diabetic rats

Diabetes is one of the major health issues globally. Type 1 diabetes mellitus develops due to the destruction of pancreatic β cells. Mesenchymal stem cells (MSCs) having remarkable self-renewal and differentiation potential, can regenerate β cells. MSCs preconditioned with bioactive small molecules possess enhanced biological features and therapeutic potential under in vivo environment. Interestingly, compounds of naphthoquinone class possess antidiabetic and anti-inflammatory properties, and can be explored as potential candidates for preconditioning MSCs. This study analyzed the effect of lawsone-preconditioned human umbilical cord MSCs (hUMSCs) on the regeneration of β cells in the streptozotocin (STZ)-induced Type 1 diabetes (T1D) rats. hUMSCs were isolated and characterized for the presence of surface markers. MSCs were preconditioned with optimized concentration of lawsone. T1D rat model was established by injecting 50 mg/kg of STZ intraperitoneally. Untreated and lawsone-preconditioned hUMSCs were transplanted into the diabetic rats via tail vein. Fasting blood sugar and body weight were monitored regularly for 4 weeks. Pancreas was harvested and β cell regeneration was evaluated by hematoxylin and eosin staining, and gene expression analysis. Immunohistochemistry was also done to assess the insulin expression. Lawsone-preconditioned hUMSCs showed better anti-hyperglycemic effect in comparison with untreated hUMSCs. Histological analysis presented the regeneration of islets of Langerhans with upregulated expression of βcell genes and reduced expression of inflammatory markers. Immunohistochemistry revealed strong insulin expression in the preconditioned hUMSCs compared with the untreated hUMSCs. It is concluded from the present study that lawsone-preconditioned hMSCs were able to exhibit pronounced anti-hyperglycemic effect in vivo compared with hUMSCs alone.

Chemical Hypoxic Preconditioning Improves Survival and Proliferation of Mesenchymal Stem Cells

Increasing evidence has demonstrated that mesenchymal stem cells (MSCs) have been linked to tissue regeneration both in vitro and in vivo. However, poor engraftment and low survival rate of transplanted MSCs are still a major concern. It has been found that the proliferation, survival, and migration of MSCs are all increased by hypoxic preconditioning. However, the molecular mechanism through which hypoxic preconditioning enhances these beneficial properties of MSCs remains to be fully investigated. Therefore, the present study is aimed to investigate the mechanism by which hypoxic preconditioning enhances the survival of MSCs. We used proteomic analysis to explore the molecules that may contribute to the survival and proliferation of hypoxic preconditioned (HP) MSCs. The analysis revealed a higher expression of prelamin A/C (Lmna), glutamate dehydrogenase 1(Glud1), Actin, cytoplasmic 1(Actb), Alpha-enolase (Eno1), Glucose-6-phosphate 1-dehydrogenase (G6pd), Protein disulfide-isomerase A3 (Pdia3), Malate dehydrogenase (Mdh1), Peroxiredoxin-6 (Prdx6), Superoxide dismutase (Sod1), and Annexin A2 (Anxa2) in HP-MSCs. These proteins are possibly involved in cellular survival and proliferation through various cellular pathways. This research could aid in understanding the processes involved in hypoxic preconditioning of MSCs and designing of cell-based therapeutic strategies for tissue regeneration.

Ascorbic acid and salvianolic acid B enhance the valproic acid and 5-azacytidinemediated cardiac differentiation of mesenchymal stem cells

BACKGROUND

Cardiovascular diseases remain a major cause of death globally. Cardiac cells once damaged, cannot resume the normal functioning of the heart. Bone marrow derived mesenchymal stem cells (BM-MSCs) have shown the potential to differentiate into cardiac cells. Epigenetic modifications determine cell identity during embryo development via regulation of tissue specific gene expression. The major epigenetic mechanisms that control cell fate and biological functions are DNA methylation and histone modifications. However, epigenetic modifiers alone are not sufficient to generate mature cardiac cells. Various small molecules such as ascorbic acid (AA) and salvianolic acid B (SA) are known for their cardiomyogenic potential. Therefore, this study is aimed to examine the synergistic effects of epigenetic modifiers, valproic acid (VPA) and 5-azacytidine (5-aza) with cardiomyogenic molecules, AA and SA in the cardiac differentiation of MSCs.

METHODS AND RESULTS

BM-MSCs were isolated, propagated, characterized, and then treated with an optimized dose of VPA or 5-aza for 24 h. MSCs were maintained in a medium containing AA and SA for 21 days. All groups were assessed for the expression of cardiac genes and proteins through q-PCR and immunocytochemistry, respectively. Results show that epigenetic modifiers VPA or 5-aza in combination with AA and SA significantly upregulate the expression of cardiac genes MEF2C, Nkx2.5, cMHC, Tbx20, and GATA-4. In addition, VPA or 5-aza pretreatment along with AA and SA enhanced the expression of the cardiac proteins connexin-43, GATA-4, cTnI, and Nkx2.5.

CONCLUSION

These findings suggest that epigenetic modifiers valproic acid and 5-azacytidine in combination with ascorbic acid and salvianolic acid B promote cardiac differentiation of MSCs. This pretreatment strategy can be exploited for designing future stem cell based therapeutic strategies for cardiovascular diseases.

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.

Mesenchymal Stem Cell-Derived Extracellular Vesicles Protect Rat Nucleus Pulposus Cells from Oxidative Stress

BACKGROUND

Oxidative stress (OS) is mainly associated with the pathogenesis of intervertebral disc (IVD) degeneration; it causes nucleus pulposus cells (NPCs) to undergo senescence and triggers autophagy and apoptosis. This study aims to evaluate the regeneration potential of extracellular vesicles (EVs) derived from human umbilical cord-mesenchymal stem cells (hUC-MSCs) in an in vitro rat NPC-induced OS model.

DESIGN

NPCs were isolated from rat coccygeal discs, propagated, and characterized. OS was induced by hydrogen peroxide (H₂O₂), which is confirmed by 2,7-dichlorofluorescein diacetate (H₂DCFDA) assay. EVs were isolated from hUC-MSCs and characterized by analyzing the vesicles using fluorescence microscope, scanning electron microscope (SEM), atomic force microscope (AFM), dynamic light scattering (DLS), and Western blot (WB). The in vitro effects of EVs on migration, uptake, and survival of NPCs were determined.

RESULTS

SEM and AFM topographic images revealed the size distribution of EVs. The phenotypes of isolated EVs showed that the size of EVs was 403.3 ± 85.94 nm, and the zeta potential was -0.270 ± 4.02 mV. Protein expression analysis showed that EVs were positive for CD81 and annexin V. Treatment of NPCs with EVs reduced H₂O₂-induced OS as evidenced by a decrease in reactive oxygen species (ROS) levels. Co-culture of NPCs with DiI-labeled EVs showed the cellular internalization of EVs. In the scratch assay, EVs significantly increased NPC proliferation and migration toward the scratched area. Quantitative polymerase chain reaction analysis showed that EVs significantly reduced the expression of OS genes.

CONCLUSION

EVs protected NPCs from H₂O₂-induced OS by reducing intracellular ROS generation and improved NPC proliferation and migration.

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&amp;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.

Alpha terpineol directs bone marrow mesenchymal stem cells toward neuronal lineage through regulation of wnt signaling pathway

Central nervous system anomalies give rise to neuropathological consequences with immense damage to the neuronal tissues. Cell based therapeutics have the potential to manage several neuropathologies whereby the differentiated cells are explored for neuronal regeneration. The current study analyzes the effect of a bioactive compound, alpha terpineol (AT) on the differentiation of rat bone marrow derived mesenchymal stem cells (BM-MSCs) toward neuronal lineage, and explores regulation of differentiation process through the study of Wnt pathway mediators. BM-MSCs were cultured and characterized based on their surface markers and tri-lineage differentiation. Safe dose of AT as optimized by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium bromide assay, was used for the treatment of MSCs. Treated cells were analyzed for the neuronal, astroglial and germ layer transition markers at the gene and protein levels, by quantitative polymerase chain reaction and immunocytochemistry, respectively. Temporal expression of Wnt pathway genes was assessed during the course of neuronal differentiation. AT treated group showed significant upregulation of neuron specific (NSE, MAP2, Tau, Nestin, and NefL) and astroglial (GFAP) genes with positive expression of late neuronal markers. Germ layer transition analysis showed the overexpression of ectodermal markers (NCAM, Nestin, and Pax6), whereas endodermal (AFP, MixL1, and Sox17), and mesodermal (Mesp1 and T Brachyury) markers were also found to be upregulated. Wnt signaling pathway was activated during the initial phase (30 min) of differentiation, which later was downregulated at 1, 3, and 5 h. AT efficiently induces neuronal differentiation of BM-MSCs by regulating Wnt signaling. Overexpression of both early and late neuronal markers indicate their neuro-progenitor state and thus can be utilized as a promising approach in cellular therapeutics to treat various neurodegenerative ailments. In addition, exploration of the molecular pathways may be helpful to understand the mechanism of cell-based neuronal regeneration.

Minocycline pre-treatment up-regulates antioxidant enzymes and enhances the regenerative potential of MSCs in rat myocardial infarction model

Objectives

To determine the effect of the pre-treatment of mesenchymal stem cells (MSCs) with minocycline on the expression of antioxidant genes and cardiac repair post myocardial infarction (MI) in rats.

METHODS

Rat bone marrow derived MSCs were used in the study. Cytotoxicity of minocycline in MSCs was determined using JC1 assay to identify a safe drug dose for further experiments. The MSCs were pre-treated with 1.0 µM minocycline for 24 hours and then treated with hydrogen peroxide (H2O2), after that mRNA was isolated and the expression levels of antioxidant genes including peroxiredoxin, glutathione peroxidase, and superoxide dismutase were determined. Finally, minocycline pre-treated MSCs were used to treat rats induced with MI by the ligation of left anterior descending coronary artery. The cardiac function was evaluated at two and four weeks post MI using echocardiography.

RESULTS

At 1.0 µM concentration, minocycline was found to be safe for MSCs and used for subsequent experiments. Minocycline pre-treatment was found to up regulate several antioxidant genes in oxidatively stressed MSCs. Furthermore, minocycline pre-treated MSCs displayed greater improvement in cardiac left ventricular function at two and four-weeks post MI as compared to untreated rats.

CONCLUSIONS

Pre-treatment of MSCs with minocycline enhances the expression of antioxidant genes and promotes their capability to repair cardiac function after MI.

Cardiac Transcription Regulators Differentiate Human Umbilical Cord Mesenchymal Stem Cells into Cardiac Cells

Stem cell-based therapy presents an attractive alternative to conventional therapies for degenerative diseases. Numerous studies have investigated the capability of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) to contribute to the regeneration of cardiomyocytes, and the results have encouraged further basic and clinical studies on the MSC-based treatment of cardiomyopathies. This study aimed to determine the potential of cardiomyogenic transcription factors in differentiating hUC-MSCs into cardiac-like cells in vitro. MSCs were isolated from umbilical cord tissue and were transduced with the transcription factor genes, GATA-4 and Nkx 2.5, via infection with lentiviruses, to promote differentiation into the cardiomyogenic lineage. Gene and protein expression were analysed with qPCR and immunocytochemical staining. After transduction, differentiated cardiac-like cells showed significant expression of cardiac genes and proteins, namely GATA-4, Nkx-2.5, cardiac troponin I (cTnI) and myosin heavy chain (MHC). The cardiomyogenic-induced group significantly overexpressed cardiac-specific genes (GATA-4, Nkx-2.5, cTnI, MHC, α-actinin and Wnt2). Expression of the calcium channel gene was also significantly increased, while the sodium channel gene was downregulated in the transduced hUC-MSCs, as compared to non-transduced cells. The results suggest that GATA-4 and Nkx-2.5 interact synergistically in the activation of downstream cardiac transcription factors, demonstrating the functional convergence of hUC-MSC differentiation into cardiac-like cells. These findings could potentially be utilised in the efficient production of cardiac-like cells from stem cells; these cardiac-like cells could then be used in various applications, such as for in vivo implantation in infarcted myocardium, and for drug screening in toxicity testing.

Rutin and quercetagetin enhance the regeneration potential of young and aging bone marrow-derived mesenchymal stem cells in the rat infarcted myocardium

Myocardial infarction (MI) damages cardiomyocytes permanently and compromises cardiac function. Mesenchymal stem cells (MSCs) with the potential to differentiate into multiple lineages are considered as one of the best options for the treatment of MI. However, aging affects their regeneration capability. With age, reactive oxygen species (ROS) accumulate in cells ultimately causing cell death. To successfully utilize these stem cells in clinic, novel strategies to improve their functional capability should be explored. In this study, we aimed to enhance the cardiac regeneration potential of bone marrow MSCs derived from aging rats by treating them with antioxidants, rutin or quercetagetin in separate in vivo experiments. Oxidative stress was induced by treating MSCs of young and aging rats with different concentrations of H₂O₂ which resulted in an increase in the ROS level. MSCs were treated with rutin or quercetagetin at varying concentrations and exposed to H₂O₂. It was observed that both antioxidants significantly (P < 0.001) suppressed H₂O₂-induced intracellular ROS accumulation in a dose-dependent manner. An optimized concentration of 10 µM rutin or quercetagetin was used for the in vivo experiments. MI models were developed in aging rats by ligation of left anterior descending artery and treated MSCs were transplanted in the MI models. Echocardiography was performed after 2 and 4 weeks of cell transplantation to evaluate the functional status of the infarcted heart and histological analysis was performed after 4 weeks to assess cardiac regeneration. Significant improvement was observed in cardiac parameters including LVEF% (P < 0.001), LVFS% (P < 0.01 and P < 0.001), LVIDd (P < 0.01 and P < 0.001), LVIDs (P < 0.001), LVEDV (P < 0.001) and LVESV (P < 0.001) in the treated young as well as aging MSCs. It is concluded from these findings that rutin and quercetagetin treatment enhance the regeneration efficiency of young and aging MSCs in vivo. These antioxidants can be effectively utilized to improve cellular therapy for myocardial infarction by suppressing ROS production.

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.

The role of epigenetic modifiers in the hepatic differentiation of human umbilical cord derived mesenchymal stem cells

Human umbilical cord (hUC) derived mesenchymal stem cells (MSCs) can be progressively differentiated into multiple lineages including hepatic lineages, and thus provide an excellent in vitro model system for the study of hepatic differentiation. At present, hepatic differentiation protocols are based on the use of soluble chemicals in the culture medium and provide immature hepatic like cells. Histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors (DNMTi) are two important epigenetic modifiers that regulate stem cell differentiation. Therefore, this study aimed to investigate the role of HDACi, valproic acid (VPA) and DNMTi,5-azacytidine (5-aza) along with a hepatic inducer in the hepatic differentiation of hUC-MSCs. hUC-MSCs were characterized via immunocytochemistry and flow cytometry. The final concentrations of VPA and 5-aza were optimized via MTT cytotoxicity assay. All treated groups were assessed for the presence of hepatic genes and proteins through qPCR and immunocytochemistry, respectively. The results showed that the pretreatment of epigenetic modifiers not only increased the hepatic genes but also increased the expression of the hepatic proteins. VPA induces hepatic differentiation in hUC-MSCs with significant gene expression of hepatic markers i.e., FOXA2 and CK8. Moreover, VPA pretreatment enhanced the expression of hepatic proteins AFP and TAT. The pretreatment of 5-aza shows significant gene expression of hepatic marker LDL-R. However, 5-aza treatment failed to induce hepatic protein expression. The results of the current study highlighted the effectiveness of epigenetic modifiers in the hepatic differentiation of hUC-MSCs. These differentiated cells can be employed in cell-based therapeutics for hepatic diseases in future.

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.

Potential of stem cell seeded three-dimensional scaffold for regeneration of full-thickness skin wounds

Hypoxic wounds are tough to heal and are associated with chronicity, causing major healthcare burden. Available treatment options offer only limited success for accelerated and scarless healing. Traditional skin substitutes are widely used to improve wound healing, however, they lack proper vascularization. Mesenchymal stem cells (MSCs) offer improved wound healing; however, their poor retention, survival and adherence at the wound site negatively affect their therapeutic potential. The aim of this study is to enhance skin regeneration in a rat model of full-thickness dermal wound by transplanting genetically modified MSCs seeded on a three-dimensional collagen scaffold. Rat bone marrow MSCs were efficiently incorporated in the acellular collagen scaffold. Skin tissues with transplanted subcutaneous scaffolds were histologically analysed, while angiogenesis was assessed both at gene and protein levels. Our findings demonstrated that three-dimensional collagen scaffolds play a potential role in the survival and adherence of stem cells at the wound site, while modification of MSCs with jagged one gene provides a conducive environment for wound regeneration with improved proliferation, reduced inflammation and enhanced vasculogenesis. The results of this study represent an advanced targeted approach having the potential to be translated in clinical settings for targeted personalized therapy.

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.

Abstract P1138: Combination Of Pluripotency And Cardiac Transcription Factors Reprogram Skin Fibroblasts Into Cardiomyocytes

Direct reprogramming of autologous somatic cells into cardiomyocytes is a novel approach which is being employed for cardiac regeneration. Multiple studies have combined different cardiac-specific factors that could directly reprogram cardiac fibroblasts into induced cardiomyocyte-like cells. However, this approach needs heart biopsy for the isolation of autologous fibroblasts which involves extensive surgical procedures that require precision. In this study, we aimed to develop an approach which can directly reprogram somatic cells into cardiomyocyte-like cells using a combination of pluripotency and cardiac transcription factors. Skin fibroblasts were isolated from rat neonatal pups and were induced into cardiomyocyte-like cells using non-viral integration of cardiac transcription factors (GATA4, Mef2c and Nkx2.5) and OKSIM plasmid carrying the iPSC factors, Sox2, Oct4, Klf4 and cMyc. After 72 h, cells were analyzed for the expression of cardiac markers by qPCR and immunocytochemistry. Gene expression analysis showed significantly higher expression of cardiac markers GATA4, cMHC, Mef2c, cTnT, cTnI, and Nkx2.5 Immunostaining confirmed the expression of cardiac proteins GATA4, cMHC, cTnT, cTnI, and Nkx2.5. These results imply that the transfected cells started differentiating towards cardiac lineage. Transfected cells were also transplanted in rat myocardial infarction (MI) model immediately after ligation of left ventricle descending (LAD) artery. After 2 and 4 weeks of cell transplantation, the animals were assessed for cardiac function via echocardiography. They showed significant improvement in the cardiac function as compared to MI and non-transfected groups. After 4 weeks, the hearts were harvested, and histological analysis was performed for the assessment of fibrosis and left ventricular wall thickness. Rats transplanted with transfected cells showed significantly reduced fibrosis and increased wall thickness as compared to MI and non-transfected groups. In conclusion, transient and combined expression of cardiac transcription and iPSC factors in neonatal somatic cells leads to the transdifferentiation of skin cells into myogenic lineage. This approach can be useful for future therapeutic application for cardiovascular diseases.

Abstract P1137: Combination Of Zebularine Treated Rat Bone Marrow Mesenchymal Stem Cells With 3d Collagen Scaffold Preserves Ventricular Remodeling In Rat Myocardial Infarction Model

Cardiovascular diseases (CVDs) are the leading cause of death globally due to immensely high morbidity and mortality ratio. The incidence of CVD, particularly myocardial infarction (MI), is expected to increase rapidly in the coming decades. MI causes the death of myocytes, which ultimately leads to heart failure. Advancements in medical and surgical treatments can only limit the disease progress but cannot improve the function of infarcted myocardium. Therefore, a promising treatment strategy for ischemic heart diseases is highly needed. Stem cell therapy holds great potential to regenerate the injured myocardium due to the self-renewal and differentiation potential of these cells. Among various types, mesenchymal stem cells (MSCs) are potential candidates for regenerating the damaged cardiac tissue due to their multi-lineage differentiation potential and ease of isolation. However, certain issues such as poor survival and engraftment can prevent them from fully restoring normal cardiac structure and function. The use of biomaterials provides suitable microenvironment to the cells to perform various biological functions, and can solve the poor cellular engraftment problem associated with cell transplantation alone. In this study, we used natural three dimensional (3D) collagen scaffold along with demethylating agent, zebularine, for in vivo transplantation in rat MI model. Treatment with zebularine is shown to enhance cardiac differentiation of MSCs. MSCs were isolated from rat bone marrow, characterized, seeded in collagen scaffold and treated with zebularine. Cytotoxicity analysis was performed to confirm the non-cytotoxic effect of the treatments, and gene and protein expression levels were analyzed using cardiac specific primers and antibodies, respectively. In vitro analysis revealed that treatment in the 3D environment significantly enhanced cardiac differentiation of MSCs both at gene and protein levels. For in vivo analysis, rat MI model was developed and zebularine treated MSC-seeded scaffold was transplanted and compared with the MI group, along with other groups in which only collagen scaffold and untreated MSC-seeded scaffold were transplanted. Echocardiographic analysis revealed enhanced functional improvement in zebularine treated MSC-seeded group as compared to the other groups. Histological analysis revealed tissue preservation, cardiac regeneration beneath the scaffold, reduction in the fibrotic scar and improvement in the ventricular wall thickness in the treated MSC group. This strategy is expected to overcome the problems associated with cell transplantation alone and to provide an effective therapeutic strategy for improved cardiac function.

Role of Wnt/β-catenin pathway in cardiac lineage commitment of human umbilical cord mesenchymal stem cells by zebularine and 2'-deoxycytidine

Wnt/β-catenin, a highly conserved signaling pathway, is involved in determining cell fate. During heart development, Wnt signaling controls specification, proliferation and differentiation of cardiac cells. This study is aimed to investigate the role of Wnt/β-catenin signaling in cardiac lineage commitment of human umbilical cord mesenchymal stem cells (hUCMSCs) after treatment with demethylating agents, zebularine and 2'-deoxycytidine (2-DC). hUCMSCs were treated with 20 µM zebularine or 2-DC for 24 h and cultured for 14 days. Control and treated MSCs were analyzed for cardiac lineage commitment at gene and protein levels. Significant upregulation of early and late cardiac markers, GATA4, Nkx2.5, cardiac myosin heavy chain (cMHC), α-actinin, cardiac troponin T (cTnT) and cardiac troponin I (cTnI) was observed in treated MSCs as compared to the untreated control. We also analyzed gene expression of key Wnt/β-catenin signaling molecules in cultures of treated and untreated hUCMSCs at 24 h, and days 3, 7 and 14. The pattern of mRNA gene expression showed that Wnt/β-catenin signaling is regulated during cardiac lineage commitment of hUCMSCs in a time-dependent manner, with the pathway being activated early but inhibited later in cardiac development. Findings of this study can lead us to identify more specific and effective strategies for cardiac lineage commitment.

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.

Comparative analysis of dental pulp stem cells and stem cells from human exfoliated teeth in terms of growth kinetics, immunophenotype, self-renewal and multi lineage differentiation potential for future perspective of calcified tissue regeneration

Background and Objectives:

Owing to high proliferation rate, multipotency and self-renewal capability, dental pulp stem cells (DPSC) and stem cells from human exfoliated teeth (SHED) have become stem cell source of choice for cell based regenerative therapies. We aimed to compare DPSC and SHED as stem cell sources with a future use in regeneration of calcified tissue.

Methods:

Explant derived human DPSC (n=9) and SHED (n=1) were cryopreserved, thawed and expanded for analysis of population doubling time, colony forming unit assay and efficiency. A growth curve was plotted to determine population doubling time, while colony forming numbers and efficiency was determined at plating cell densities of 5.6, 11.1 and 22.2 / cm2. The isolated cells were characterized for the presence of stem cell markers by immunophenotyping and immunofluorescence staining, and tri-lineage differentiation. Statistical analysis was performed by Pearson correlation, Exponential regression and two way Anova with Tukey test at p<0.05.

Results:

DPSC and SHED exhibited spindle shaped fibroblast like morphology. SHED was found superior than DPSC in terms of proliferation and colony forming efficiency. Immunophenotypes showed that DPSC contain 62.6±26.3 %, 90.9±14.8% and 19.8±0.1%, while SHED contain 90.5%, 97.7% and 0.1% positive cells for CD90, CD73 and CD105. DPSC were strongly positive for vimentin, CD29, CD73, while reactivity was moderate to weak against CD44 and CD90. SHED expressed vimentin, CD29, CD105, CD90 and CD44. Both were negative for CD45. Upon induction, both cell types differentiated into bone, fat and cartilage like cells.

Conclusion:

Cultured DPSC and SHED were proliferative and exhibited self-renewal property. Both DPSC and SHED expressed stem cell markers and were able to differentiate into bone, fat and cartilage like cells. Thus, these could be a suitable stem cell sources for cell based regenerative therapies.

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 α-pinene and thymoquinone on the differentiation of bone marrow mesenchymal stem cells into neuroprogenitor cells

Introduction: Neurodegenerative diseases are accompanied by loss of neuronal function and integrity. Stem cell therapy is utilized to regenerate neurons to repair the damaged area. Regeneration potential of stem cells can be enhanced by using chemicals with known bioactive properties. In the current study, two bioactive compounds, α-pinene (AP) and thymoquinone (TQ) were explored for their neuronal differentiation potential of rat bone marrow mesenchymal stem cells (MSCs).

Methods: MSCs were isolated, cultured and characterized immunocytochemically for the presence of specific surface markers. Optimized concentrations of both compounds (20 µM AP and 12 µM TQ) as determined by MTT assay, were used to treat MSCs in separate and combined groups. All groups were assessed for the presence of neuronal, astroglial, and germ layer markers through qPCR. Neuronal and glial protein expression were analyzed by immunocytochemistry.

Results: Both compounds alone and in combination induced differentiation in MSCs with significant gene expression of neuronal markers i.e. neuron specific enolase (NSE), nestin, microtubule-associated protein 2 (MAP2), neurofilament light chain (Nefl) and Tau, and astroglial marker i.e. glial fibrillary acidic protein (GFAP). AP treated group also showed significant upregulation of endodermal and mesodermal markers indicating transition of ectoderm towards the other two germ layers.

Conclusion: This study concludes that AP and TQ potentially differentiate MSCs into neuronal and astroglial lineages. However, AP treated group followed germ layer transition. Expression of neuronal as well as glial markers indicate that the differentiated neurons are at the neuroprogenitor stage and can be potential candidates for cellular therapeutics against neurodegenerative disorders.

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.

Effect of valproic acid on the hepatic differentiation of mesenchymal stem cells in 2D and 3D microenvironments

Mesenchymal stem cells (MSCs) have multi-lineage differentiation potential which make them an excellent source for cell-based therapies. Histone modification is one of the major epigenetic regulations that play central role in stem cell differentiation. Keeping in view their ability to maintain gene expression essential for successful differentiation, it was interesting to examine the effects of valproic acid (VPA), a histone deacetylase inhibitor, in the hepatic differentiation of MSCs within the 3D scaffold. MSCs were treated with the optimized concentration of VPA in the 3D collagen scaffold. Analyses of hepatic differentiation potential of treated MSCs were performed by qPCR, immunostaining and periodic acid Schiff assay. Our results demonstrate that MSCs differentiate into hepatic-like cells when treated with 5 mM VPA for 24 h. The VPA-treated MSCs have shown significant upregulation in the expression of hepatic genes, CK-18 (P < 0.05), TAT (P < 0.01), and AFP (P < 0.001), and hepatic proteins, AFP (P < 0.05) and ALB (P < 0.01). In addition, acetylation of histones (H3 and H4) was significantly increased (P < 0.001) in VPA-pretreated cells. Further analysis showed that VPA treatment significantly enhanced (P < 0.01) glycogen storage, an important functional aspect of hepatic cells. The present study revealed the effectiveness of VPA in hepatic differentiation within the 3D collagen scaffold. These hepatic-like cells may have an extended clinical applicability in future for successful liver regeneration.

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.

Abstract 412: Wnt / β-catenin Inhibitor Differentiates Human Mesenchymal Stem Cells into Myogenic Lineage in vitro and Improved Cardiac Function in vivo in Rat Model of Myocardial Infarction

Cardiovascular disease (CVD) is one of the major causes of morbidity and mortality. At present, available therapeutic options for the treatment of cardiovascular diseases are limited and provide solution only to reduce the symptoms of CVD. The indigenous capability of cardiac tissue to meet the degeneration is limited. The feasible option is stem cells based regenerative medicine to repair or regenerate the myocardial cells and restore normal cardiac function. The aim of the present study is to assess the potential of small molecules for the differentiation of MSCs into cardiomyocytes. In this study, MSCs were cultured in vitro and were characterized by immunochemistry, and flow cytometry for the presence of MSCs markers, CD90, CD73, CD44, CD29, and for tri-lineage differentiation. MSCs were treated with wiki-4 for 14 days to induce cardiac differentiation, and were characterized for the presence cardiac markers by gene and protein expression for GATA-4, α-actinin, cTnT, cTnI, and myosin heavy chain, and found positive for these markers. These induced cardiac progenitor cells were transplanted into the infarcted myocardium of rats, where they exhibited increased persistence, engraftment, and homing in the infarcted region, and expressed cardiac markers within the border zone. Transplanted group improved left ventricular wall thickness at 4 weeks post injury, and reduced infarct size. Functional performance of the hearts was analyzed through M-mode echocardiography, which results in significant (p<0.05) improvement in the heart function including left ventricular internal diameter systolic and diastolic, ejection fraction, fractional shortening, end systolic volume and diastolic volume, and stroke volume compared to control. Histological examination of the heart sections 4 weeks post MI showed that MSCs home towards the site of injury. The transplanted cells expressed cardiac markers and contributed to the cardiac tissue recovery. The results of the present study demonstrate that myocytes derived of MSCs enhance the regeneration potential of the infarcted myocardium.

IL-7 overexpression enhances therapeutic potential of rat bone marrow mesenchymal stem cells for diabetic wounds

This study was aimed to enhance the healing potential of rat bone marrow mesenchymal stem cells against chronic diabetic wounds through interleukin-7 (IL-7) transfection. IL-7 plays an important role in wound healing and acts as a survival factor in some cell types. This study involves isolation, propagation, and characterization of mesenchymal stem cells (MSCs) and their modification with IL-7 gene via retroviral transfection. Transfected MSCs were assessed for their effect on angiogenic genes by qPCR. Wound healing potential of transfected MSCs was analyzed by scratch assay in vitro and by transplanting these cells in rat diabetic wound models in vivo. Wound area was measured for a period of 15 days and subsequent histological analysis was performed. qPCR results showed increased expression of IL-7 gene (p ≤ 0.05) and also principal angiogenic genes, vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), VEGF receptor 1 (FLT-1), and VEGF receptor 2 (FLK-1) (p ≤ 0.05). Neuropilin-1 (NRP-1) did not show any significant change. In vitro analysis of IL-7 MSCs showed intense cell-cell connections and tube formation as compared to the normal MSCs. Rate of wound closure was more (p ≤ 0.001) in case of diabetic group transplanted with IL-7 MSCs. Histological examination revealed enhanced vascular supply in skin tissues of diabetic animals transplanted with IL-7 transfected MSCs as compared to normal MSCs. Immunohistochemical results showed significantly higher expression of IL-7 (p ≤ 0.001) and α-smooth muscle actin(p ≤ 0.001) in the tissue sections of IL-7 transfected group as compared to normal MSCs and the diabetic control group; the latter indicates increase in the number of blood vessels. It is concluded from this study that IL-7 overexpression in MSCs can enhance the healing potential of MSCs and aid in wound closure in diabetic animals through the induction of angiogenic genes.

Abstract PD5-03: Characterization of high TIL breast cancers reveals a prognostic and functionally distinct tissue-resident memory subpopulation

Background: Tumor infiltrating lymphocytes (TILs) assessed via light microscopy are prognostic and predictive in the early stage and advanced triple negative and HER2-amplified breast cancer (BC). Higher TILs can also identify patients more likely to benefit from anti-PD-1 therapy. In this study we interrogated T cell subsets that comprise high TILs to determine if distinct subpopulations are key mediators of anti-tumor immunity.

Methods: We characterised TILs with a focus on CD3+ T cells in 129 primary and metastatic BC samples using flow cytometry, bulk RNASeq on flow sorted T cell populations, multiplex immunohistochemistry and microdroplet based single cell 3' mRNA sequencing on the 10X Genomics Chromium platform. Cell type specific gene expression signatures were determined from differential expression between putative T cell subpopulations. These signatures were investigated in clinical cohorts, including trial cohorts treated with pembrolizumab.

Results: High TIL Infiltrates consisted primarily of CD3+ T cells, with both CD8 and CD4 populations. Unsupervised clustering of single cell sequencing identified 9 CD8 and CD4 subpopulations with distinct gene expression profiles. In addition to Tregs and CD8 effector memory (TEM) T cells, we found a CD8+ tissue resident memory (TRM) population expressing greater levels of T-cell checkpoints and cytotoxic markers compared to effector memory cells. In 2 primary tumours and 1 liver metastasis, bulk RNASeq of flow sorted TEM and TRM corroborated the single cell mRNASeq results. T cell receptor profiling (TCR) in the 3 samples found non-overlapping repertoires in the 2 primary tumours, but overlap in one metastatic lesion, suggesting divergent developmental origins in the breast, but the potential for nascent TRM differentiation in a metastatic niche. Clustering of these TCRs suggested differing antigen specificities between TRM and non-TRM CD8 T cells. Using Metabric data, the CD8 TRM gene expression signature was prognostic for disease free survival (DFS) in primary TNBCs (n=329, log-rank p=0.003), and was able to further stratify cases with high and low CD8A expression for DFS (log-rank p = 0.03). The CD8 TRM signature was enriched in baseline tumour samples of responders (n = 9) compared with non-responders (n=36) in 45 patients with metastatic melanoma treated with T cell checkpoint blockade (p &lt; 0.0001). Additional single cell sequencing data with TCR sequencing will be combined with these initial results, and an independent data set of single cell mRNASeq and TCR Seq on CD3+ BC TILs will be used to confirm our findings. Cell type specific signatures will be explored in additional clinical cohorts including KEYNOTE-086, and presented at the meeting.

Conclusion: Using single cell profiling of the immune microenvironment in BC we demonstrate that high TIL BCs contain multiple T cell subpopulations with different functional and prognostic significance. Our approach identified a CD8 TRM population with a distinct gene expression profile and strong expression of key immune checkpoints likely representing the presence of true tumor specific immunity. This population may be a key target of immune checkpoint blockade.

Citation Format: Savas P, Virassamy B, Ye C, Salim A, Mintoff CP, Caramia F, Salgado R, Teo ZL, Dushyanthen S, Byrne A, Luen SJ, Fox SB, Speed TP, Mackay LK, Neeson PJ, Loi S. Characterization of high TIL breast cancers reveals a prognostic and functionally distinct tissue-resident memory subpopulation [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD5-03.

Role of interleukin-7 in fusion of rat bone marrow mesenchymal stem cells with cardiomyocytes in vitro and improvement of cardiac function in vivo

AIMS

Mesenchymal stem cells (MSCs) hold significant promise as potential therapeutic candidates following cardiac injury. However, to ensure survival of transplanted cells in ischemic environment, it is beneficial to precondition them with growth factors that play important role in cell survival and proliferation. Aim of this study is to use interleukin-7 (IL-7), a cell survival growth factor, to enhance the potential of rat bone marrow MSCs in terms of cell fusion in vitro and cardiac function in vivo.

METHODS

Mesenchymal stem cells were transfected with IL-7 gene through retroviral vector. Normal and transfected MSCs were co-cultured with neonatal cardiomyocytes (CMs) and cell fusion was analyzed by flow cytometry and fluorescence microscopy. These MSCs were also transplanted in rat model of myocardial infarction (MI) and changes at tissue level and cardiac function were assessed by histological analysis and echocardiography, respectively.

RESULTS

Co-culture of IL-7 transfected MSCs and CMs showed significantly higher (P < 0.01) number of fused cells as compared to normal MSCs. Histological analysis of hearts transplanted with IL-7 transfected MSCs showed significant reduction (P < 0.001) in infarct size and better preservation (P < 0.001) of left ventricular wall thickness as compared to normal MSCs. Presence of cardiac-specific proteins, α-actinin, and troponin-T showed that the transplanted MSCs were differentiated into cardiomyocytes. Echocardiographic recordings of the experimental group transplanted with transfected MSCs showed significant increase in the ejection fraction and fractional shortening (P < 0.01), and decrease in diastolic and systolic left ventricular internal diameters (P < 0.001) and end systolic and diastolic volumes (P < 0.01 and P < 0.001, respectively).

CONCLUSION

Interleukin-7 is able to enhance the fusogenic properties of MSCs and improve cardiac function. This improvement may be attributed to the supportive action of IL-7 on cell proliferation and cell survival contributing to the regeneration of damaged myocardium.

Interferon-γ receptor-1 gene promoter polymorphisms and susceptibility for brucellosis in Makkah region

BACKGROUND

Genetic polymorphisms that affect the production levels of certain cytokines and/or their receptors may determine the risk, severity or protection in some infectious diseases like brucellosis.

OBJECTIVES

The aim of this study was to investigate the association of certain known Interferon-γ Receptor-1 (IFN-γ R1) gene promoter polymorphisms and the susceptibility to infection with Brucellosis in Saudi population.

METHODS

A cases-control association study was conducted in 69 individuals with human brucellosis and 94 healthy individuals. Genotyping of IFN-γ R1 - 56 C>T and IFN-γ R1 - 611 A>G polymorphism in both patients and healthy controls was done by PCR- restriction enzyme length polymorphisms (PCR-RFLP) and PCR- confronting two primer pairs (PCR-CTPP) methods and were assessed for potential associations with susceptibility for human brucellosis and their mode of penetrance.

RESULTS

Interestingly, we have designed a PCR-CTPP system to be used for genotyping of IFN-γ R1 - 611 A > G polymorphism. The PCR-CTPP is an accurate method for genotyping of SNPs. Moreover, it is time-saving, inexpensive and easy to perform.

CONCLUSION

Both tested polymorphisms, IFN-γ R1 - 56 C>T and IFN-γ R1 -611 A>G polymorphism had no role in genetic susceptibility to human brucellosis in the study population. The PCR-CTPP can be used for genotyping IFN-γ R1 - 611 A > G polymorphism and other types of mutation.