Liver-derived human mesenchymal stem cells: a novel therapeutic source for liver diseases

Exploring the roles of non-coding RNAs in liver regeneration

Liver regeneration (LR) is a complex process encompassing three distinct phases: priming, proliferation phase and restoration, all influenced by various regulatory factors. After liver damage or partial resection, the liver tissue demonstrates remarkable restorative capacity, driven by cellular proliferation and repair mechanisms. The essential roles of non-coding RNAs (ncRNAs), predominantly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNA (circRNA), in regulating LR have been vastly studied. Additionally, the impact of ncRNAs on LR and their abnormal expression profiles during this process have been extensively documented. Mechanistic investigations have revealed that ncRNAs interact with genes involved in proliferation to regulate hepatocyte proliferation, apoptosis and differentiation, along with liver progenitor cell proliferation and migration. Given the significant role of ncRNAs in LR, an in-depth exploration of their involvement in the liver's self-repair capacity can reveal promising therapeutic strategies for LR and liver-related diseases. Moreover, understanding the unique regenerative potential of the adult liver and the mechanisms and regulatory factors of ncRNAs in LR are crucial for improving current treatment strategies and exploring new therapeutic approaches for various liver-related diseases. This review provides a brief overview of the LR process and the ncRNA expression profiles during this process. Furthermore, we also elaborate on the specific molecular mechanisms through which multiple key ncRNAs regulate the LR process. Finally, based on the expression characteristics of ncRNAs and their interactions with proliferation-associated genes, we explore their potential clinical application, such as developing predictive indicators reflecting liver regenerative activity and manipulating LR processes for therapeutic purposes.

Stem cell-based therapy for fibrotic diseases: mechanisms and pathways

Fibrosis is a pathological process, that could result in permanent scarring and impairment of the physiological function of the affected organ; this condition which is categorized under the term organ failure could affect various organs in different situations. The involvement of the major organs, such as the lungs, liver, kidney, heart, and skin, is associated with a high rate of morbidity and mortality across the world. Fibrotic disorders encompass a broad range of complications and could be traced to various illnesses and impairments; these could range from simple skin scars with beauty issues to severe rheumatologic or inflammatory disorders such as systemic sclerosis as well as idiopathic pulmonary fibrosis. Besides, the overactivation of immune responses during any inflammatory condition causing tissue damage could contribute to the pathogenic fibrotic events accompanying the healing response; for instance, the inflammation resulting from tissue engraftment could cause the formation of fibrotic scars in the grafted tissue, even in cases where the immune system deals with hard to clear infections, fibrotic scars could follow and cause severe adverse effects. A good example of such a complication is post-Covid19 lung fibrosis which could impair the life of the affected individuals with extensive lung involvement. However, effective therapies that halt or slow down the progression of fibrosis are missing in the current clinical settings. Considering the immunomodulatory and regenerative potential of distinct stem cell types, their application as an anti-fibrotic agent, capable of attenuating tissue fibrosis has been investigated by many researchers. Although the majority of the studies addressing the anti-fibrotic effects of stem cells indicated their potent capabilities, the underlying mechanisms, and pathways by which these cells could impact fibrotic processes remain poorly understood. Here, we first, review the properties of various stem cell types utilized so far as anti-fibrotic treatments and discuss the challenges and limitations associated with their applications in clinical settings; then, we will summarize the general and organ-specific mechanisms and pathways contributing to tissue fibrosis; finally, we will describe the mechanisms and pathways considered to be employed by distinct stem cell types for exerting anti-fibrotic events.

Oral ulcer treatment using human tonsil-derived mesenchymal stem cells encapsulated in trimethyl chitosan hydrogel: an animal model study

BACKGROUND

Oral ulcers are a common side effect of chemotherapy and affect patients' quality of life. While stem cell transplantation is a potential treatment for oral ulcers, its efficacy is limited as the stem cells tend to remain in the affected area for a short time. This study aims to develop a treatment for oral ulcers by using trimethyl chitosan (TMC) hydrogel with human tonsil-derived stem cells (hTMSCs) to increase the therapeutic effect of stem cells and investigate their effectiveness.

METHODS

Animals were divided into four experimental groups: Control, TMC hydrogel, hTMSCs, and hTMSCs loaded in TMC hydrogel (Hydrogel + hTMSCs) (each n = 8). Oral ulcers were chemically induced by anesthetizing the rats followed by injection of dilute acetic acid in the right buccal mucosa. After confirming the presence of oral ulcers in the animals, a single subcutaneous injection of 100 µL of each treatment was applied to the ulcer area. Histological analyses were performed to measure inflammatory cells, oral mucosal thickness, and fibrosis levels. The expression level of inflammatory cytokines was also measured using RT-PCR to gauge therapeutic the effect.

RESULTS

The ulcer size was significantly reduced in the TMC hydrogel + hTMSCs group compared to the control group. The stem cells in the tissue were only observed until Day 3 in the hTMSCs treated group, while the injected stem cells in the TMC Hydrogel + hTMSCs group were still present until day 7. Cytokine analysis related to the inflammatory response in the tissue confirmed that the TMC Hydrogel + hTMSCs treated group demonstrated superior wound healing compared to other experimental groups.

CONCLUSION

This study has shown that the adhesion and viability of current stem cell therapies can be resolved by utilizing a hydrogel prepared with TMC and combining it with hTMSCs. The combined treatment can promote rapid healing of oral cavity wounds by enhancing anti-inflammatory effects and expediting wound healing. Therefore, hTMSC loaded in TMC hydrogel was the most effective wound-healing approach among all four treatment groups prolonging stem cell survival. However, further research is necessary to minimize the initial inflammatory response of biomaterials and assess the safety and long-term effects for potential clinical applications.

Strategies to improve the therapeutic efficacy of mesenchymal stem cell-derived extracellular vesicle (MSC-EV): a promising cell-free therapy for liver disease

Liver disease has emerged as a significant worldwide health challenge due to its diverse causative factors and therapeutic complexities. The majority of liver diseases ultimately progress to end-stage liver disease and liver transplantation remains the only effective therapy with the limitations of donor organ shortage, lifelong immunosuppressants and expensive treatment costs. Numerous pre-clinical studies have revealed that extracellular vesicles released by mesenchymal stem cells (MSC-EV) exhibited considerable potential in treating liver diseases. Although natural MSC-EV has many potential advantages, some characteristics of MSC-EV, such as heterogeneity, uneven therapeutic effect, and rapid clearance in vivo constrain its clinical translation. In recent years, researchers have explored plenty of ways to improve the therapeutic efficacy and rotation rate of MSC-EV in the treatment of liver disease. In this review, we summarized current strategies to enhance the therapeutic potency of MSC-EV, mainly including optimization culture conditions in MSC or modifications of MSC-EV, aiming to facilitate the development and clinical application of MSC-EV in treating liver disease.

The Dual Role of Mesenchymal Stem Cells in Cancer Pathophysiology: Pro-Tumorigenic Effects versus Therapeutic Potential

Mesenchymal stem/stromal cells (MSCs) are multipotent cells involved in numerous physiological events, including organogenesis, the maintenance of tissue homeostasis, regeneration, or tissue repair. MSCs are increasingly recognized as playing a major, dual, and complex role in cancer pathophysiology through their ability to limit or promote tumor progression. Indeed, these cells are known to interact with the tumor microenvironment, modulate the behavior of tumor cells, influence their functions, and promote distant metastasis formation through the secretion of mediators, the regulation of cell-cell interactions, and the modulation of the immune response. This dynamic network can lead to the establishment of immunoprivileged tissue niches or the formation of new tumors through the proliferation/differentiation of MSCs into cancer-associated fibroblasts as well as cancer stem cells. However, MSCs exhibit also therapeutic effects including anti-tumor, anti-proliferative, anti-inflammatory, or anti-oxidative effects. The therapeutic interest in MSCs is currently growing, mainly due to their ability to selectively migrate and penetrate tumor sites, which would make them relevant as vectors for advanced therapies. Therefore, this review aims to provide an overview of the double-edged sword implications of MSCs in tumor processes. The therapeutic potential of MSCs will be reviewed in melanoma and lung cancers.

Advances in Understanding the Roles of Mesenchymal Stem Cells in Lung Cancer

Lung cancer is the most common and deadliest type of cancer worldwide. Research concerning lung cancer has made considerable progress in recent decades, but lung cancer remains the leading cause of malignancy-related mortality rate. Mesenchymal stem cells (MSCs) mainly exist in fat, umbilical cord blood, bone marrow, bone, and muscle. MSCs are a primary component of the tumor microenvironment (TME). Recent studies have shown that MSCs have roles in lung cancer-related proliferation, invasion, migration, and angiogenesis, but the underlying mechanisms are poorly understood. Because MSCs can migrate to the TME, there is increasing attention toward the use of MSCs in drugs or gene vectors for cancer treatment. This review summarizes the roles and effects of MSCs in lung cancer, while addressing clinical applications of MSCs in lung cancer treatment.

Stem cells for treatment of liver fibrosis/cirrhosis: clinical progress and therapeutic potential

Cost-effective treatment strategies for liver fibrosis or cirrhosis are limited. Many clinical trials of stem cells for liver disease shown that stem cells might be a potential therapeutic approach. This review will summarize the published clinical trials of stem cells for the treatment of liver fibrosis/cirrhosis and provide the latest overview of various cell sources, cell doses, and delivery methods. We also describe the limitations and strengths of various stem cells in clinical applications. Furthermore, to clarify how stem cells play a therapeutic role in liver fibrosis, we discuss the molecular mechanisms of stem cells for treatment of liver fibrosis, including liver regeneration, immunoregulation, resistance to injury, myofibroblast repression, and extracellular matrix degradation. We provide a perspective for the prospects of future clinical implementation of stem cells.

Exosomes Derived from Baicalin-Pretreated Mesenchymal Stem Cells Alleviate Hepatocyte Ferroptosis after Acute Liver Injury via the Keap1-NRF2 Pathway

Acute liver injury (ALI) is characterized as a severe metabolic dysfunction caused by extensive damage to liver cells. Ferroptosis is a type of cell death dependent on iron and oxidative stress, which differs from classical cell death, such as apoptosis and necrosis. Ferroptosis has unique morphological features, which mainly include mitochondrial dissolution and mitochondrial outline reduction. Furthermore, the intracellular accumulation of lipid peroxides directly affects the occurrence of ferroptosis. Baicalin, the main compound isolated from Scutellaria baicalensis, has anti-inflammatory and antioxidative effects. Recently, exosomes derived from preconditioned mesenchymal stem cells (MSCs) have shown great potential in the treatment of various diseases including ALI. This study investigates the ability of exosomes derived from baicalin-pretreated MSCs (Ba-Exo) to promote liver function recovery in mice with ALI compared with those without pretreatment. Through in vivo and in vitro experiments, this study demonstrates for the first time that Ba-Exo greatly attenuates D-galactosamine and lipopolysaccharide (D-GaIN/LPS)-induced liver damage and inhibits reactive oxygen species (ROS) production and lipid peroxide-induced ferroptosis. Moreover, P62 was significantly upregulated in Ba-Exo, whereas its downregulation in Ba-Exo counteracted the beneficial effect of Ba-Exo. P62 regulates hepatocyte ferroptosis by activating the Keap1-NRF2 pathway. The beneficial effect of Ba-Exo in inhibiting ferroptosis was also attenuated after the NRF2 pathway was inhibited. Therefore, baicalin pretreatment is an effective and promising approach to optimize the therapeutic efficacy of MSC-derived exosomes in ALI.

Stem Cell Therapy: From Idea to Clinical Practice

Regenerative medicine is a new and promising mode of therapy for patients who have limited or no other options for the treatment of their illness. Due to their pleotropic therapeutic potential through the inhibition of inflammation or apoptosis, cell recruitment, stimulation of angiogenesis, and differentiation, stem cells present a novel and effective approach to several challenging human diseases. In recent years, encouraging findings in preclinical studies have paved the way for many clinical trials using stem cells for the treatment of various diseases. The translation of these new therapeutic products from the laboratory to the market is conducted under highly defined regulations and directives provided by competent regulatory authorities. This review seeks to familiarize the reader with the process of translation from an idea to clinical practice, in the context of stem cell products. We address some required guidelines for clinical trial approval, including regulations and directives presented by the Food and Drug Administration (FDA) of the United States, as well as those of the European Medicine Agency (EMA). Moreover, we review, summarize, and discuss regenerative medicine clinical trial studies registered on the Clinicaltrials.gov website.

In vitro differentiation of human bone marrow stromal cells into neural precursor cells using small molecules

BACKGROUND

Neurogenic differentiation of human marrow stromal stem cells (hMSCs) into neural precursor cells (NPCs) offers new hope in many neurological diseases. Stromal cells can be differentiated into NPCs using small molecules acting as chemical inducers. The aim of this study is to formulate an efficient, direct, fast and safe protocol to differentiate hMSCs into NPCs using different inducers: b-mercaptoethanol (BME), triiodothyronine (T3), and curcumin (CUR). NEW METHOD: hMSCs were subjected to either 1 mM BME, 0.5 µM T3, or 5 µM CUR. Neurogenic differentiation was determined by assessing the protein expression of PAX6, SOX2, DLX2, and GAP-43 with flow cytometry and immunofluorescence, along with Nissl staining of differentiated cells.

RESULTS AND COMPARISON WITH EXISTING METHOD

It was revealed that T3 and CUR are 70-80% better than BME in terms of efficiency and safety, and surprisingly BME was a good promoting factor for cell preconditioning with limited effects on neural trans-differentiation related to its toxic effects on cell viability.

CONCLUSION

Reprogramming of bone marrow stromal cells into neural cells gives hope for treating different neurological disorders. Our study shows that T3 and CUR were effective in generation of NPCs from hMSCs with preservation of cell viability. BME was a good promoting factor for cell preconditioning with limited effects on neural transdifferentiation related to its toxic effects on cell viability.

Mesenchymal Stem/Stromal Cell-Derived Extracellular Vesicles for Chronic Kidney Disease: Are We There Yet?

Mesenchymal stem/stromal cells (MSCs) are the most utilized cell type for cellular therapy, partly due to their important proliferative potential and ability to differentiate into various cell types. MSCs produce large amounts of extracellular vesicles (EVs), which carry genetic and protein cargo to mediate MSC paracrine function. Recently, MSC-derived EVs have been successfully used in several preclinical models of chronic kidney disease. However, uncertainty remains regarding EV fate, safety, and long-term effects, which might impose important limitations on their path to clinical translation. This review discusses the therapeutic application of MSC-derived EV therapy for renal disease, with particular emphasis on potential mechanisms of kidney repair and major translational barriers. Emerging evidence indicates that the cargo of MSC-derived EVs is capable of modulating several pathways responsible for renal injury, including inflammation, oxidative stress, apoptosis, fibrosis, and microvascular remodeling. EV-induced modulation of these pathways has been associated with important renoprotective effects in experimental studies. However, scarce clinical data are available, and several challenges need to be addressed as we move toward clinical translation, including standardization of methods for EV isolation and characterization, EV fate, duration of EV effects, and effects of cardiovascular risk factors. MSC-derived EVs have the potential to preserve renal structure and function, but further experimental and clinical evidence is needed to confirm their protective effects in patients with chronic kidney disease.

Human delta like 1-expressing human mesenchymal stromal cells promote human T cell development and antigen-specific response in humanized NOD/SCID/IL-2R[Formula: see text]null (NSG) mice

Human delta-like 1 (hDlk1) is known to be able to regulate cell fate decisions during hematopoiesis. Mesenchymal stromal cells (MSCs) are known to exhibit potent immunomodulatory roles in a variety of diseases. Herein, we investigated in vivo functions of hDlk1-hMSCs and hDlk1+hMSCs in T cell development and T cell response to viral infection in humanized NOD/SCID/IL-2Rγnull (NSG) mice. Co-injection of hDlk1-hMSC with hCD34+ cord blood (CB) cells into the liver of NSG mice markedly suppressed the development of human T cells. In contrast, co-injection of hDlk1+hMSC with hCD34+ CB cells into the liver of NSG dramatically promoted the development of human T cells. Human T cells developed in humanized NSG mice represent markedly diverse, functionally active, TCR V[Formula: see text] usages, and the restriction to human MHC molecules. Upon challenge with Epstein-Barr virus (EBV), EBV-specific hCD8+ T cells in humanized NSG mice were effectively mounted with phenotypically activated T cells presented as hCD45+hCD3+hCD8+hCD45RO+hHLA-DR+ T cells, suggesting that antigen-specific T cell response was induced in the humanized NSG mice. Taken together, our data suggest that the hDlk1-expressing MSCs can effectively promote the development of human T cells and immune response to exogenous antigen in humanized NSG mice. Thus, the humanized NSG model might have potential advantages for the development of therapeutics targeting infectious diseases in the future.

Stem cell transplantation for treating liver diseases: progress and remaining challenges

With the development of regenerative medicine, various stem cells are increasingly considered for treating liver diseases. Various stem cells have been reported to play an essential role in liver recovery, and studies have verified the preliminary effectiveness and safety of these therapies. Stem cell-based therapies will emerge as an effective treatment strategy for liver diseases. Thus, the research progress and challenges to the related stem cells were reviewed, namely the classification of stem cells, cell culture, transplantation, cell tracing in the body, therapies for various liver diseases.

Directed differentiation of human induced pluripotent stem cells to hepatic stellate cells

Hepatic stellate cells (HSCs) are nonparenchymal liver cells responsible for extracellular matrix homeostasis and are the main cells involved in the development of liver fibrosis following injury. The lack of reliable sources of HSCs has hence limited the development of complex in vitro systems to model liver diseases and toxicity. Here we describe a protocol to differentiate human induced pluripotent stem cells (iPSCs) into hepatic stellate cells (iPSC-HSCs). The protocol is based on the addition of several growth factors important for liver development sequentially over 12 d. iPSC-HSCs present phenotypic and functional characteristics of primary HSCs and can be expanded or frozen and used to perform high-throughput in vitro studies. We also describe how to coculture iPSC-HSCs with hepatocytes, which self-assemble into three-dimensional (3D) hepatic spheroids. This protocol enables the generation of HSC-like cells for in vitro modeling and drug screening studies.

A bioartificial liver support system integrated with a DLM/GelMA-based bioengineered whole liver for prevention of hepatic encephalopathy via enhanced ammonia reduction

Although bioartificial liver support systems (BLSSs) play an essential role in maintaining partial liver functions and detoxification for liver failure patients, hepatocytes are unanimously seeded in biomaterials, which lack the hierarchal structures and mechanical cues of native liver tissues. To address this challenge, we developed a new BLSS by combining a decellularized liver matrix (DLM)/GelMA-based bioengineered whole liver and a perfusion-based, oxygenated bioreactor. The novel bioengineered whole liver was fabricated by integrating photocrosslinkable gelatin (GelMA) and hepatocytes into a DLM. The combination of GelMA and the DLM not only provided a biomimetic extracellular microenvironment (ECM) for enhanced cell immobilization and growth with elevated hepatic functions (e.g., albumin secretion and CYP activities), but also provided biomechanical support to maintain the native structure of the liver. In addition, the perfusion-based, oxygenated bioreactor helped deliver oxygen to the interior tissues of the bioengineered liver, which was of importance for long-term culture. Most importantly, this new bioengineered whole liver decreased ammonia concentration by 45%, whereas direct seeding of hepatocytes in a naked DLM showed no significant reduction. Thus, the developed BLSS integrated with the DLM/GelMA-based bioengineered whole liver can potentially help elevate liver functions and prevent HE in liver failure patients while waiting for liver transplantation.

Immunomodulatory and Regenerative Effects of Mesenchymal Stem Cells and Extracellular Vesicles: Therapeutic Outlook for Inflammatory and Degenerative Diseases

Mesenchymal stem cells (MSCs) are non-hematopoietic, multipotent stem cells derived from mesoderm, which can be easily isolated from many sources such as bone marrow, umbilical cord or adipose tissue. MSCs provide support for hematopoietic stem cells and have an ability to differentiate into multiple cell lines. Moreover, they have proangiogenic, protective and immunomodulatory properties. MSCs have the capacity to modulate both innate and adaptive immune responses, which accompany many diseases, by inhibiting pro-inflammatory reactions and stimulating anti-inflammatory activity. Recent findings revealed that the positive effect of MSCs is at least partly associated with the production of extracellular vesicles (EVs). EVs are small membrane structures, containing proteins, lipids and nuclei acids, which take part in intra-cellular communication. Many studies indicate that EVs contain protective and pro-regenerative properties and can modulate an immune response that is activated in various diseases such as CNS diseases, myocardial infarction, liver injury, lung diseases, ulcerative colitis or kidney injury. Thus, EVs have similar functions as their cells of origin and since they do not carry the risk of cell transplantation, such as tumor formation or small vessel blockage, they can be considered a potential therapeutic tool for cell-free therapy.

Antioxidative Capacity of Liver- and Adipose-Derived Mesenchymal Stem Cell-Conditioned Media and Their Applicability in Treatment of Type 2 Diabetic Rats

Type 2 diabetes mellitus (T2DM) is mainly characterized by insulin resistance and impaired insulin secretion, which cannot be reversed with existing therapeutic strategies. Using mesenchymal stem cells (MSCs), cell-based therapy has been demonstrated in displaying therapeutic effects in T2DM for their self-renewable, differentiation potential, and immunosuppressive properties and higher levels of angiogenic factors. Stem cell therapies are complicated and have a serious adverse effect including tumor formation and immunogenicity, while using mesenchymal stem cell-conditioned media (MSC-CM) significantly reduces stem cell risk, maintaining efficacy and showing significantly higher levels of growth factors, cytokines, and angiogenic factors that stimulate angiogenesis and promote fracture healing in diabetes. In the present study, we investigated the therapeutic potential of the liver and adipose MSC-CM in diabetic endothelial dysfunction compared with standard insulin therapy. Fifty adult male Sprague Dawley rats were divided equally into 5 groups as follows: control, diabetic, diabetic+insulin, diabetic+liver MSC-CM, and diabetic+adipose MSC-CM; all treatments continued for 4 weeks. Finally, we observed that liver MSC-CM therapy had the most apparent improvement in levels of blood glucose; HbA1c; AGEs; lipid panel (cholesterol, TG, LDL, HDL, and total lipids); renal function (urea, uric acid, creatinine, and total protein); liver function (AST, ALT, ALP, bilirubin, and albumin); CPK; C-peptide; HO-1; inflammatory markers including IL-6, TNF-α, and CRP; growth factors (liver and serum IGF-1); amylase; histopathological changes; pancreatic cell oxidative stress; and antioxidant markers (MDA, GSH, ROS, CAT, SOD, HO-1, and XO) toward the normal levels compared with insulin and adipose MSCs-CM. Moreover, both the liver and adipose MSC-CM relieved the hyperglycemic status by improving pancreatic islet β cell regeneration, promoting the conversion of alpha cells to beta cells, reducing insulin resistance, and protecting pancreatic tissues against oxidative stress-induced injury as well as possessing the ability to modulate immunity and angiogenesis. These results indicated that MSC-CM infusion has therapeutic effects in T2DM rats and may be a promising novel therapeutic target.

Cell Sources and Influencing Factors of Liver Regeneration: A Review

Liver regeneration (LR) is a set of complicated mechanisms between cells and molecules in which the processes of initiation, maintenance, and termination of liver repair are regulated. Although LR has been studied extensively, there are still numerous challenges in gaining its full understanding. Cells for LR have a wide range of sources and the feature of plasticity, and regeneration patterns are not the same under different conditions. Many patients undergoing partial hepatectomy develop cirrhosis or steatosis. The changes of LR in these cases are not clear. Many types of cells participate in LR. Hepatocytes, biliary epithelial cells, hepatic progenitor cells, and human liver stem cells can serve as the cell sources for LR. However, different types and degrees of damage trigger the response from the most suitable cells. Exploring the cell sources of LR is of great significance for accelerating recovery of liver function under different pathological patterns and developing a cell therapy strategy to cope with the shortage of donors for liver transplantation. In clinical practice, the background of the liver influences regeneration. Fibrosis and steatosis create different LR microenvironments and signal molecule interaction patterns. In addition, factors such as partial hepatectomy, aging, platelets, nerves, hormones, bile acids, and gut microbiota are widely involved in this process. Understanding the influencing factors of LR has practical value for individualized treatment of patients with liver diseases. In this review, we have summarized recent studies and proposed our views. We discuss cell sources and the influential factors on LR to help in solving clinical problems.

Biomaterials functionalized with MSC secreted extracellular vesicles and soluble factors for tissue regeneration

The therapeutic benefits of mesenchymal stromal cell (MSC) transplantation have been attributed to their secreted factors, including extracellular vesicles (EVs) and soluble factors. The potential of employing the MSC secretome as an alternative acellular approach to cell therapy is being investigated in various tissue injury indications, but EVs administered via bolus injections are rapidly sequestered and cleared. However, biomaterials offer delivery platforms to enhance EV retention rates and healing efficacy. In this review, we highlight the mechanisms underpinning the therapeutic effects of MSC-EVs and soluble factors as effectors of immunomodulation and tissue regeneration, conferred primarily via their nucleic acid and protein contents. We discuss how manipulating the cell culture microenvironment or genetic modification of MSCs can further augment the potency of their secretions. The most recent advances in the development of EV-functionalized biomaterials that mediate enhanced angiogenesis and cell survival, while attenuating inflammation and fibrosis, are presented. Finally, some technical challenges to be considered for the clinical translation of biomaterials carrying MSC-secreted bioactive cargo are discussed.

The mechanisms of cellular crosstalk between mesenchymal stem cells and natural killer cells: Therapeutic implications

Mesenchymal stem cells (MSCs) are mesenchymal precursors of various origins, with well-known immunomodulatory effects. Natural killer (NK) cells, the major cells of the innate immune system, are critical for the antitumor and antiviral defenses; however, in certain cases, they may be the main culprits in the pathogenesis of some NK-related conditions such as autoimmunities and hematological malignancies. On the other hand, these cells seem to be the major responders in beneficial phenomena like graft versus leukemia. Substantial data suggest that MSCs can variably affect NK cells and can be affected by these cells. Accordingly, acquiring a profound understanding of the crosstalk between MSCs and NK cells and the involved mechanisms seems to be a necessity to develop therapeutic approaches based on such interactions. Therefore, in this study, we made a thorough review of the existing literature on the interactions between MSCs and NK cells with a focus on the underlying mechanisms. The current knowledge herein suggests that MSCs possess a great potential to be used as tools for therapeutic targeting of NK cells in disease context and that preconditioning of MSCs, as well as their genetic manipulation before administration, may provide a wider variety of options in terms of eliciting more specific and desirable therapeutic outcomes. Nevertheless, our knowledge regarding the effects of MSCs on NK cells is still in its infancy, and further studies with well-defined conditions are warranted herein.

Hepatogenic Potential and Liver Regeneration Effect of Human Liver-derived Mesenchymal-Like Stem Cells

Human liver-derived stem cells (hLD-SCs) have been proposed as a possible resource for stem cell therapy in patients with irreversible liver diseases. However, it is not known whether liver resident hLD-SCs can differentiate toward a hepatic fate better than mesenchymal stem cells (MSCs) obtained from other origins. In this study, we compared the differentiation ability and regeneration potency of hLD-SCs with those of human umbilical cord matrix-derived stem cells (hUC-MSCs) by inducing hepatic differentiation. Undifferentiated hLD-SCs expressed relatively high levels of endoderm-related markers (GATA4 and FOXA1). During directed hepatic differentiation supported by two small molecules (Fasudil and 5-azacytidine), hLD-SCs presented more advanced mitochondrial respiration compared to hUC-MSCs. Moreover, hLD-SCs featured higher numbers of hepatic progenitor cell markers on day 14 of differentiation (CPM and CD133) and matured into hepatocyte-like cells by day 7 through 21 with increased hepatocyte markers (ALB, HNF4A, and AFP). During in vivo cell transplantation, hLD-SCs migrated into the liver of ischemia-reperfusion injury-induced mice within 2 h and relieved liver injury. In the thioacetamide (TAA)-induced liver injury mouse model, transplanted hLD-SCs trafficked into the liver and spontaneously matured into hepatocyte-like cells within 14 days. These results collectively suggest that hLD-SCs hold greater hepatogenic potential, and hepatic differentiation-induced hLD-SCs may be a promising source of stem cells for liver regeneration.

Phenotypic, Transcriptional, and Functional Analysis of Liver Mesenchymal Stromal Cells and Their Immunomodulatory Properties

The liver is an immunologically active organ with a tolerogenic microenvironment at a quiescent state. The immunoregulatory properties of the liver appear to be retained after transplantation because liver allografts can reduce alloresponses against other organs that are simultaneously transplanted. Mechanisms of this phenomenon remain unknown. Given the known immunomodulatory properties of mesenchymal stromal cells (MSCs), we hypothesized that liver mesenchymal stromal cells (L-MSCs) are superior immunomodulators and contribute to liver-mediated tolerance. L-MSCs, generated from human liver allograft biopsies, were compared with adipose mesenchymal stromal cells (A-MSCs) and bone marrow mesenchymal stromal cells (BM-MSCs). Trilineage differentiation of L-MSCs was confirmed by immunohistochemistry. Comparative phenotypic analyses were done by flow cytometry and transcriptome analyses by RNA sequencing in unaltered cell cultures. The in vitro functional analyses were performed using alloreactive T cell proliferation assays. The transcriptome analysis showed that the L-MSCs are different than the A-MSCs and BM-MSCs, with significant enrichment of genes and gene sets associated with immunoregulation. Compared with the others, L-MSCs were found to express higher cell surface levels of several select immunomodulatory molecules. L-MSCs (versus A-MSCs/BM-MSCs) inhibited alloreactive T cell proliferation (22.7% versus 56.4%/58.7%, respectively; P < 0.05) and reduced the frequency of interferon ɤ-producing T cells better than other MSCs (52.8% versus 94.4%/155.4%; P < 0.05). The antiproliferative impact of L-MSCs was not dependent on cell-to-cell contact, could be reversed incompletely by blocking programmed death ligand 1, and required a higher concentration of the competitive inhibitor of indoleamine 2,3-dioxygenase for complete reversal. In conclusion, L-MSCs appear to be uniquely well-equipped immunomodulatory cells, and they are more potent than A-MSCs and BM-MSCs in that capacity, which suggests that they may contribute to liver-induced systemic tolerance.

Human adipose-derived mesenchymal stem cells inhibit proliferation and induce apoptosis of human gastric cancer HGC-27 cells

The aim of this study was to explore the effects of human adipose-derived mesenchymal stem cells (ASCs) on the growth of gastric cancer cells in vivo and vitro and its mechanism. ASCs were isolated from abandoned adipose tissues, and the surface markers were identified by flow cytometry. In vitro experiments, HGC-27 cells cultured in ASCs-conditioned medium (CM) were assigned as the experimental group, while HGC-27 cells cultured in normal medium were as the control group. MTT and colony formation assays were performed to detect cell viability and colony formatting ability, respectively. Annexin-V/PI assay, Western blot, and caspase-3 enzyme activity assay were performed to detect cells apoptosis. The isolated ASCs could be differentiated into adipocytes and osteoblasts in vitro. Flow cytometry showed that CD73 and CD105 were positively expressed in HGC-27 cells. Compared with the mice injected HGC-27 cells only, the tumor formation in mice injected both ASCs and HGC-27 cells was significantly smaller (P < 0.05). The colony formation ability in experimental group was 40.09% smaller than control group (P < 0.05) and the cell apoptosis rate in experimental group was higher than the control group (P < 0.05). Furthermore, the expressions of cleaved PARP, cleaved caspase-3 proteins, and caspase-3 enzyme viability in experimental group were significantly higher than those of control group (P < 0.05). In conclusion, ASCs can effectively inhibit the growth of HGC-27 cells by inducing apoptosis.

Bone marrow mesenchymal stem cell-derived exosomes attenuate D-GaIN/LPS-induced hepatocyte apoptosis by activating autophagy in vitro

Background

Acute liver failure is an inflammation-mediated hepatocyte injury. Mesenchymal stem cell (MSC) transplantation is currently considered to be an effective treatment strategy for acute liver failure. Exosomes are an important paracrine factor that can be used as a direct therapeutic agent. However, the use of bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) in the treatment of acute liver failure has not been reported.

Purpose

Here, we established a model of hepatocyte injury and apoptosis induced by D-galactosamine and lipopolysaccharide (D-GalN/LPS) to study the protective effect of BMSC-Exos on hepatocyte apoptosis, and further explored its protective mechanism.

Methods

BMSC-Exos was identified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and Western blot. Laser confocal microscopy was used to observe the uptake of Dil-Exos by hepatocytes. D-GalN/LPS-induced primary hepatocytes were pretreated with BMSC-Exos in vitro, and then the cells were harvested. The apoptosis of hepatocytes was observed by TUNEL staining, flow cytometry and Western blot. Electron microscopy and mRFP-GFP-LC3 and Western blot was used to observe autophagy.

Results

BMSC-Exos increased the expression of autophagy marker proteins LC3 and Beclin-1 and promoted the formation of autophagosomes. After BMSC-Exos treatment, the expression levels of the proapoptotic proteins Bax and cleaved caspase-3 were significantly decreased, while the expression level of the anti-apoptotic protein Bcl-2 was upregulated. However, when the autophagy inhibitor 3MA was present, the effect of BMSC-Exos on inhibiting apoptosis was significantly reversed.

Conclusions

Our results showed for the first time that BMSC-Exos had the potential to reduce hepatocyte apoptosis after acute liver failure. In particular, we found that BMSC-Exos attenuated hepatocyte apoptosis by promoting autophagy. 

Application of Tonsil-Derived Mesenchymal Stem Cells in Tissue Regeneration: Concise Review

Since the discovery of stem cells and multipotency characteristics of mesenchymal stem cells (MSCs), there has been tremendous development in regenerative medicine. MSCs derived from bone marrow have been widely used in various research applications, yet there are limitations such as invasiveness of obtaining samples, low yield and proliferation rate, and questions regarding their practicality in clinical applications. Some have suggested that MSCs from other sources, specifically those derived from palatine tonsil tissues, that is, tonsil‐derived MSCs (TMSCs), could be considered as a new potential therapeutic tool in regenerative medicine due to their superior proliferation rate and differentiation capabilities with low immunogenicity and ease of obtaining. Several studies have determined that TMSCs have differentiation potential not only into the mesodermal lineage but also into the endodermal as well as ectodermal lineages, expanding their potential usage and placing them as an appealing option to consider for future studies in regenerative medicine. In this review, the differentiation capacities of TMSCs and their therapeutic competencies from past studies are addressed. stem cells2019;37:1252–1260

Dysfunctional Immune Response in Acute-on-Chronic Liver Failure: It Takes Two to Tango

Acute-on-chronic liver failure (ACLF) is characterized by the acute decompensation of cirrhosis associated with organ failure and high short-term mortality. The key event in the pathogenesis is a dysfunctional immune response arising from exacerbation of the two main immunological alterations already present in cirrhosis: systemic inflammation and immune cell paralysis. High-grade systemic inflammation due to predominant activation and dysregulation of the innate immune response leads to the massive release of cytokines. Recognition of acutely increased pathogen and damage-associated molecular patterns by specific receptors underlies its pathogenesis and contributes to tissue damage and organ failure. In addition, an inappropriate compensatory anti-inflammatory response over the course of ACLF, along with the exhaustion and dysfunction of both the innate and adaptive immune systems, leads to functional immune cell paralysis. This entails a high risk of infection and contributes to a poor prognosis. Therapeutic approaches seeking to counteract the immune alterations present in ACLF are currently under investigation.

Human liver stem cells attenuate concanavalin A-induced acute liver injury by modulating myeloid-derived suppressor cells and CD4+ T cells in mice

BACKGROUND

Acute liver failure (ALF) is a serious threat to the life of people all over the world. Finding an effective way to manage ALF is important. Human liver stem cells (HLSCs) are early undifferentiated cells that have been implicated in the regeneration and functional reconstruction of the liver. In this study, we aimed to evaluate the protective effects of the HLSC line HYX1 against concanavalin A (ConA)-induced acute liver injury.

METHODS

HYX1 cells were characterized by microscopy, functional assays, gene expression, and western blot analyses. We showed that HYX1 cells can differentiate into hepatocytes. We intraperitoneally injected HYX1 cells in mice and administered ConA via caudal vein injection 3, 6, 12, 24, and 48 h later. The effects of HYX1 cell transplantation were evaluated through blood tests, histology, and flow cytometry.

RESULTS

HYX1 cells reduced the levels of alanine transaminase (ALT), aspartate aminotransferase (AST), and total bilirubin (TBIL) in serum and dramatically decreased the severity of liver injuries. Mechanistically, HYX1 cells promoted myeloid-derived suppressor cell (MDSC) migration into the spleen and liver, while reducing CD4⁺ T cell levels in both tissues. In addition, HYX1 cells suppressed the secretion of proinflammatory cytokines, such as tumour necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), but led to increased interleukin-10 (IL-10) production.

CONCLUSIONS

These results confirm the efficacy of HLSCs in the prevention of the ConA-induced acute liver injury through modulation of MDSCs and CD4⁺ T cell migration and cytokine secretion.

The mesenchymal stem cell secretome as an acellular regenerative therapy for liver disease

The use of mesenchymal stem cells (MSC) for tissue repair has garnered much interest and has been evaluated in several disease settings. Recent evidence indicates that the beneficial effects observed with MSC-based therapy can be mediated through the paracrine release of extracellular vesicles and other soluble proteins or biologically active molecules, which collectively constitute the MSC secretome. In this concise overview, we highlight results from preclinical and other studies that demonstrate the therapeutic efficacy of the MSC secretome for diseases that are characterized by liver injury or fibrosis. The potential for the use of the MSC secretome as an acellular regenerative therapy and approaches for the isolation of a secretome product for therapeutic applications are highlighted. The use of the MSC secretome as an acellular therapeutic agent could provide several advantages over the use of cell-based therapies for liver diseases.

Ectopic expression of factor VIII in MSCs and hepatocytes derived from rDNA targeted hESCs

Hemophilia A is an X-linked recessive bleeding disorder caused by FVIII gene deficiency, which may result in spontaneous joint hemorrhages or life-threatening bleeding. Currently, cell-based gene therapy via ex vivo transduction of transplantable cells with integrating gene-expressing vectors offers an attractive treatment for HA. In present study, we targeted an expression cassette of B-domain-deleted FVIII into the ribosomal DNA (rDNA) locus of human embryonic stem cells (hESCs) by transfection with a nonviral targeting plasmid pHrn. The targeted hESCs clone could be expanded and retained the main pluripotent properties of differentiation into three germ layers both in vitro and in vivo. Importantly, under defined induction conditions, the targeted hESCs could differentiated into functional mesenchymal stem cells (MSCs) and hepatocytes, as validated by relevant specific cell markers and functional examination. Tumorgenesis assay demonstrated that these cells are relatively safe for future applications. Analysis on gene expression revealed that exogenous FVIII mRNA and FVIII proteins were both present in differentiated MSCs and hepatocytes. These results indicated that through gene targeting at hESCs rDNA locus a persistent cell source of transplantable genetic-modified cells can be accomplished for HA therapy.

Marrow Adiposity and Hematopoiesis in Aging and Obesity: Exercise as an Intervention

PURPOSE OF REVIEW

Changes in the bone marrow microenvironment, which accompany aging and obesity, including increased marrow adiposity, can compromise hematopoiesis. Here, we review deleterious shifts in molecular, cellular, and tissue activity and consider the potential of exercise to slow degenerative changes associated with aging and obesity.

RECENT FINDINGS

While bone marrow hematopoietic stem cells (HSC) are increased in frequency and myeloid-biased with age, the effect of obesity on HSC proliferation and differentiation remains controversial. HSC from both aged and obese environment have reduced hematopoietic reconstitution capacity following bone marrow transplant. Increased marrow adiposity affects HSC function, causing upregulation of myelopoiesis and downregulation of lymphopoiesis. Exercise, in contrast, can reduce marrow adiposity and restore hematopoiesis. The impact of marrow adiposity on hematopoiesis is determined mainly through correlations. Mechanistic studies are needed to determine a causative relationship between marrow adiposity and declines in hematopoiesis, which could aid in developing treatments for conditions that arise from disruptions in the marrow microenvironment.

Tumor-promoting cyanotoxin microcystin-LR does not induce procarcinogenic events in adult human liver stem cells

HL1-hT1 cell line represents adult human liver stem cells (LSCs) immortalized with human telomerase reverse transcriptase. In this study, HL1-hT1 cells were found to express mesenchymal markers (vimentin, CD73, CD90/THY-1 and CD105) and an early hepatic endoderm marker FOXA2, while not expressing hepatic progenitor (HNF4A, LGR5, α-fetoprotein) or differentiated hepatocyte markers (albumin, transthyretin, connexin 32). In response to microcystin-LR (MC-LR), a time- and concentration-dependent formation of MC-positive protein bands in HL1-hT1 cells was observed. Cellular accumulation of MC-LR occurred most likely via mechanisms independent on organic anion transporting polypeptides (OATPs) or multidrug resistance (MDR) proteins, as indicated (a) by a gene expression analysis of 11 human OATP genes and 4 major MDR genes (MDR1/P-glycoprotein, MRP1, MRP2 and BCRP); (b) by non-significant effects of OATP or MDR1 inhibitors on MC-LR uptake. Accumulation of MC-positive protein bands in HL1-hT1 cells was associated neither with alterations of cell viability and growth, dysregulations of ERK1/2 and p38 kinases, reactive oxygen species formation, induction of double-stranded DNA breaks nor modulations of stress-inducible genes (ATF3, HSP5). It suggests that LSCs might have a selective, MDR1-independent, survival advantage and higher tolerance towards MC-induced cytotoxic, genotoxic or cancer-related events than differentiated adult hepatocytes, fetal hepatocyte or malignant liver cell lines. HL1-hT1 cells provide a valuable in vitro tool for studying effects of toxicants and pharmaceuticals on LSCs, whose important role in the development of chronic toxicities and liver diseases is being increasingly recognized.

Human umbilical cord mesenchymal stem cells inhibit proliferation of hepatic stellate cells in vitro

The effect of human umbilical cord mesenchymal stem cells (hUC-MSCs) on the proliferation of hepatic stellate cells (HSCs) is largely unknown. The purpose of this study was to explore the mechanism of action of hUC-MSCs on the proliferation of HSCs in vitro. The upper and lower double-cell co-culture system was established between hUC-MSCs and HSCs in the experimental group. HSCs were cultured alone as a negative control group. Cell proliferation and apoptosis were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry, respectively. Cell supernatants were harvested to determine the concentration of transforming growth factor-β1 (TGF-β1) by ELISA. mRNA and protein of TGF-β1, Smad3 and Smad7 in HSCs were determined by reverse transcription-polymerase chain reaction and western blotting, respectively. In the co-culture group, the proliferation of HSCs was significantly inhibited compared with the negative control group at 24 and 48 h (p<0.05). Apoptosis of HSCs in the co-culture group increased compared with that in the negative control group, which was more obvious at 48 h (p<0.05). The concentration of TGF-β1 in the co-culture group was significantly lower than in the HSCs cultured alone (p<0.05). After HSCs were co-cultured with hUC-MSCs for 48 h, expression of TGF-β1 and Smad3 mRNA and protein was reduced and expression of Smad7 mRNA and protein was increased compared with the negative control group (p<0.05). hUC-MSCs inhibited proliferation of HSCs, possibly through inhibiting TGF-β1 and Smad3 expression and increasing Smad7 protein expression.

Current Perspectives Regarding Stem Cell-Based Therapy for Liver Cirrhosis

Liver cirrhosis is a major cause of mortality and a common end of various progressive liver diseases. Since the effective treatment is currently limited to liver transplantation, stem cell-based therapy as an alternative has attracted interest due to promising results from preclinical and clinical studies. However, there is still much to be understood regarding the precise mechanisms of action. A number of stem cells from different origins have been employed for hepatic regeneration with different degrees of success. The present review presents a synopsis of stem cell research for the treatment of patients with liver cirrhosis according to the stem cell type. Clinical trials to date are summarized briefly. Finally, issues to be resolved and future perspectives are discussed with regard to clinical applications.

Comparable osteogenic capacity of mesenchymal stem or stromal cells derived from human amnion membrane and bone marrow

So far, substantial attentions have been attracted to the application of mesenchymal stem or stromal cells (MSCs) in different therapeutic approaches. Although human bone marrow is commonly considered as a major source for MSCs, having an invasive collection method, ethical consideration and donor availability create a challenge for scientists, leading them to explore better alternative sources for MSCs. The study presented here aimed to characterize and compare osteogenic capacity of MSCs obtained from the amnion membrane (AM) with those originated from BM. Cells isolated from AMs and BMs were cultured in DMEM-low glucose supplemented with FBS, penicillin and streptomycin. After 24 h of incubation, cells adhered to the plastic surface of the flasks were allowed to proliferate for more days. A sub-confluent culture of cells was trypsinized and re-cultured. The MSCs were characterized by the expression of specific markers with flow cytometry. The osteogenic differentiation of MSCs was also validated by alkaline phosphatase and alizarian red S staining. Our results showed comparable expression of MSCs specific markers for both MSC sources (AM and BM). We also showed the optimum osteogenic differentiation of MSCs from both sources whereas hAM-MSCs revealed higher proliferation rate. We found no essential immunophenotypic differences between MSCs originated from bone marrow and amnion membrane while their differentiations into osteoblastic linage were also comparable. This was in addition to the higher proliferation rate observed for hAM-MSCs which suggests hAM as an easily accessible and reliable source of MSCs applicable for bone engineering, regenerative medicine or other therapeutic approaches.

Current Understanding of Stem Cell and Secretome Therapies in Liver Diseases

Liver failure is one of the main risks of death worldwide, and it originates from repetitive injuries and inflammations of liver tissues, which finally leads to the liver cirrhosis or cancer. Currently, liver transplantation is the only effective treatment for the liver diseases although it has a limitation due to donor scarcity. Alternatively, cell therapy to regenerate and reconstruct the damaged liver has been suggested to overcome the current limitation of liver disease cures. Several transplantable cell types could be utilized for recovering liver functions in injured liver, including bone marrow cells, mesenchymal stem cells, hematopoietic stem cells, macrophages, and stem cell-derived hepatocytes. Furthermore, paracrine effects of transplanted cells have been suggested as a new paradigm for liver disease cures, and this application would be a new strategy to cure liver failures. Therefore, here we reviewed the current status and challenges of therapy using stem cells for liver disease treatments.

A decade of progress in liver regenerative medicine

Liver diseases can be caused by viral infection, metabolic disorder, alcohol consumption, carcinoma or injury, chronically progressing to end-stage liver disease or rapidly resulting in acute liver failure. In either situation, liver transplantation is most often sought for life saving, which is, however, significantly limited by severe shortage of organ donors. Until now, tremendous multi-disciplinary efforts have been dedicated to liver regenerative medicine, aiming at providing transplantable cells, microtissues, or bioengineered whole liver via tissue engineering, or maintaining partial liver functions via extracorporeal support. In both directions, new compatible biomaterials, stem cell sources, and bioengineering approaches have fast-forwarded liver regenerative medicine towards potential clinical applications. Another important progress in this field is the development of liver-on-a-chip technologies, which enable tissue engineering, disease modeling, and drug testing under biomimetic extracellular conditions. In this review, we aim to highlight the last decade's progress in liver regenerative medicine from liver tissue engineering, bioartificial liver devices (BAL), to liver-on-a-chip platforms, and then to present challenges ahead for further advancement.

MSX1-Induced Neural Crest-Like Reprogramming Promotes Melanoma Progression

Melanoma cells share many biological properties with neural crest stem cells. Here we show that the homeodomain transcription factor MSX1, which is significantly correlated with melanoma disease progression, reprograms melanocytes and melanoma cells toward a neural crest precursor-like state. MSX1-reprogrammed normal human melanocytes express the neural crest marker p75 and become multipotent. MSX1 induces a phenotypic switch in melanoma, which is characterized by an oncogenic transition from an E-cadherin-high nonmigratory state toward a ZEB1-high invasive state. ZEB1 up-regulation is responsible for the MSX1-induced migratory phenotype in melanoma cells. Depletion of MSX1 significantly inhibits melanoma metastasis in vivo. These results show that neural crest-like reprogramming achieved by a single factor is a critical process for melanoma progression.

Liver epithelioid progenitor cells derived from fetal Luxi bovine alleviate liver fibrosis

Liver epithelioid progenitor cells (LEPCs) have important roles in liver therapy because of their hepatic differentiation potency in vitro and in vivo. Despite many researches on humans, mice, and rats, equivalent progenitor cells derived from bovine are relatively rare. The purpose of our current study is to characterize bovine LEPCs, and research on the cure potency of this heteroplastic progenitor cells on mice liver fibrosis. We have used collagenase IV digesting and differential adhesion method to isolate slabstone shape, EpCAM, LGR5, NCAM1 and SOX9 positive progenitor cells from fetal Luxi bovine liver. When cultured in hepatic differentiation media containing 20 ng/ml Oncostatin M, LEPCs can differentiate into hepatocytes in vitro. After 4 weeks of intravenous tail vein injection into CCl₄-injured mouse liver, LEPCs engrafted into liver parenchyma, differentiated into ALB positive hepatocytes, and could alleviate liver fibrosis through down regulating fibrosis genes-Tgfb1 and α-SMA as well as decreasing expression of collagen gene Col1a1, Col3a1, and Col4a1, and regain liver function by recovering ALT and AST. Our findings provided a useful tool for studying liver development in vitro, new cell resource for heterograft on mouse liver diseases, and a new platform for researches on immune rejection of heterogeneous cell transplantation.

New MSC: MSCs as pericytes are Sentinels and gatekeepers

Human Mesenchymal Stem Cells, hMSCs, were first named over 25 years ago with the "stem cell" nomenclature derived from the fact that we and others could cause these cells to differentiate into a number of different mesodermal phenotypes in cell culture. The capacity to form skeletal tissue in vitro encouraged the use of hMSCs for the fabrication of tissue engineered skeletal repair tissue with subsequent transplantation to in vivo sites. With the current realization that MSCs are derived from perivascular cells, pericytes, and the immunomodulatory and trophic capabilities of MSCs in both in vitro and in vivo test systems, a complete re-evaluation of the role and functions of MSCs in the body was required. Additionally, the skeleton is a preferred organ for cancer dissemination from various tumor malignancies. To date, most efforts to understand skeletal metastasis have focused on the invasive and digestive capability of disseminated tumor cells (DTCs). The contribution of the target organ-specific microvascular structure influencing extravasation is less well understood. Current targeted cancer therapies are designed to alter not only biological functions in DTCs, but also components of the tumor stroma/microenvironment such as blood vessels. We now have a comprehensive image of the critical role of the host vasculature as an instructive niche for DTCs. The focus of this manuscript is to present the current information about MSC function in situ and to emphasize how these new observations provide insight into understanding the role of the pericyte/MSC in skeletal activities including our new hypothesis for how these cells act as a gatekeeper for metastasis of melanoma into bone. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1151-1159, 2017.

A Comparative Study to Evaluate Myogenic Differentiation Potential of Human Chorion versus Umbilical Cord Blood-derived Mesenchymal Stem Cells

OBJECTIVE

Musculodegenerative diseases threaten the life of many patients in the world. Since drug administration is not efficient in regeneration of damaged tissues, stem cell therapy is considered as a good strategy to restore the lost cells. Since the efficiency of myogenic differentiation potential of human Chorion- derived Mesenchymal Stem Cells (C-MSCs) has not been addressed so far; we set out to evaluate myogenic differentiation property of these cells in comparison with Umbilical Cord Blood- derived Mesenchymal Stem Cells (UCB-MSCs) in the presence of 5-azacytidine.

MATERIALS & METHODS

To do that, neonate placenta Umbilical Cord Blood were transferred to the lab. After characterization of the isolated cells using flowcytometry and multilineage differentiation capacity, the obtained Mesenchymal Stem Cells were cultured in DMEM/F12 supplemented with 2% FBS and 10μM of 5-azacytidine to induce myogenic differentiation. Real-time PCR and immunocytochemistry were used to assess the myogenic properties of the cells.

RESULTS

Our data showed that C-MSCs and UCB-MSCs were spindle shape in morphology. They were positive for CD90, CD73 and CD44 antigens, and negative for hematopoietic markers. They also differentiated into osteoblast and adipoblast lineages. Real-time PCR results showed that the cells could express MyoD, desmin and α-MHC at the end of the first week (P<0.05). No significant upregulation was detected in the expression of GATA-4 in both groups. Immunocytochemical staining revealed the expression of Desmin, cTnT and α-MHC.

CONCLUSIONS

Results showed that these cells are potent to differentiate into myoblast- like cells. An upregulation in the expression of some myogenic markers (desmin, α- MHC) was observed in C-MSCs in comparison with UCB-MSCs.

Does vitamin C have the ability to augment the therapeutic effect of bone marrow-derived mesenchymal stem cells on spinal cord injury?

Methylprednisolone (MP) is currently the only drug confirmed to exhibit a neuroprotective effect on acute spinal cord injury (SCI). Vitamin C (VC) is a natural water-soluble antioxidant that exerts neuroprotective effects through eliminating free radical damage to nerve cells. Bone marrow mesenchymal stem cells (BMMSCs), as multipotent stem cells, are promising candidates in SCI repair. To evaluate the therapeutic effects of MP, VC and BMMSCs on traumatic SCI, 80 adult male rats were randomly divided into seven groups: control, SCI (SCI induction by weight-drop method), MP (SCI induction, followed by administration of 30 mg/kg MP via the tail vein, once every other 6 hours, for five times), VC (SCI induction, followed by intraperitoneal administration of 100 mg/kg VC once a day, for 28 days), MP + VC (SCI induction, followed by administration of MP and VC as the former), BMMSCs (SCI induction, followed by injection of 3 × 10⁶ BMMSCs at the injury site), and BMMSCs + VC (SCI induction, followed by BMMSCs injection and VC administration as the former). Locomotor recovery was assessed using the Basso Mouse Scale. Injured spinal cord tissue was evaluated using hematoxylin-eosin staining and immunohistochemical staining. Expression of transforming growth factor-beta, tumor necrosis factor-alpha, and matrix metalloproteinase-2 genes was determined using real-time quantitative PCR. BMMSCs intervention better promoted recovery of nerve function of rats with SCI, mitigated nerve cell damage, and decreased expression of transforming growth factor-beta, tumor necrosis factor-alpha, and matrix metalloproteinase-2 genes than MP and/or VC. More importantly, BMMSCs in combination with VC induced more obvious improvements. These results suggest that VC can enhance the neuroprotective effects of BMMSCs against SCI.

Prospects for Adult Stem Cells in the Treatment of Liver Diseases

Hepatocytes constitute the main bulk of the liver and perform several essential functions. After injury, the hepatocytes have a remarkable capacity to regenerate and restore functionality. However, in some cases, the endogenous hepatocytes cannot replicate or restore the function, and liver transplantation, which is not exempt of complications, is required. Stem cells offer in theory the possibility of generating unlimited supply of hepatocytes in vitro due to their capacity to self-renew and differentiate when given the right cues. Stem cells isolated from an array of tissues have been investigated for their capacity to differentiate into hepatocyte-like cells in vitro and are employed in rescue experiments in vivo. Adult stem cells have gained in attractiveness over embryonic stem cells for liver cell therapy due to their origin, multipotentiality, and the possibility of autologous transplantation. This review deals with the promise and limitations of adult stem cells in clinically restoring liver functionality.