Bone marrow-derived mesenchymal stem cells effectively regenerate fibrotic liver in bile duct ligation rat model

Potential impact of mesenchymal stem cells on nephrotoxicity induced by gamma irradiation and antiepileptic drugs cotherapy in rats

The goal of this study was to assess the influence of bone marrow-derived mesenchymal stem cells (BM-MSCs) on the nephrotoxicity induced by fractionated doses of gamma irradiation (Rad) and the cotherapy of levetiracetam and oxcarbazepine in male rats. Adult rats were randomly divided into four groups. Group I: Control, Group II: antiepileptic drugs (AEDs), Group III: AEDs +Rad and Group IV: AEDs + Rad + MSCs. Rats treated with AEDs and exposed to fractionated doses of γ-irradiation displayed a discernible increase in serum urea, creatinine, kidney injury marker, kidney malondialdehyde, transforming growth factor beta (TGF-β) and the relative expression of Smad3 along with a decrease in the relative expression of Smad7 and glutathione level. Alternatively, groups treated with BM-MSCs with AEDs and Rad showed a substantial modification in the majority of the evaluated parameters and looked to be successful in reducing the hazards of the combination therapy of AEDs and radiation. The reno-histopathological study supports the biochemical analysis. In conclusion, BM-MSCs exhibited therapeutic potential against nephrotoxicity induced by fractionated doses of γ-irradiation and AEDs. The outcome was brought about by the downregulation of the TGF-β/Smad pathway. BM-MSCs might be suggested as a valuable therapeutic strategy to overcome kidney injury induced by gamma irradiation during AEDs cotherapy.

Evaluation of in vivo and ex vivo pre-treated bone marrow-derived mesenchymal stem cells with resveratrol in streptozotocin-induced type 1 diabetic rats

OBJECTIVES

To compare the therapeutic potential of rat bone marrow-derived mesenchymal stem cells (BM-MSCs) preconditioned ex-vivo with resveratrol (MCR) and BM-MSCs isolated from resveratrol-pre-treated rats (MTR) in type-1 diabetic rats.

METHODS

Type-1 diabetes was induced by a single streptozotocin injection (50 mg/kg; ip) in 24 rats. Following the confirmation of T1DM, diabetic rats were randomly divided into four groups: diabetic control (DC), diabetic rats treated with insulin subcutaneous (7.5 IU/kg/day), diabetic rats treated with MCR cells (3 × 106cells/rat, intravenous) and diabetic rats treated with MTR cells (3 × 106cells/rat, intravenous). Rats were sacrificed 4 weeks following cellular transplantation.

KEY FINDINGS

Untreated diabetic rats suffered from pancreatic cell damage, had high blood glucose levels, increased apoptotic, fibrosis, and oxidative stress markers and decreased survival and pancreatic regeneration parameters. Both MSCs preconditioned ex-vivo with RES and MSCs isolated from rats pre-treated with RES homed successfully in injured pancreas and showed therapeutic potential in the treatment of STZ-induced T1DM. MCR cells showed better efficiency than MTR cells.

CONCLUSIONS

The pre-conditioning of BM-MSCs with resveratrol may be a promising therapeutic possibility in T1DM. Resveratrol-preconditioned BM-MSCs encouraged effects almost comparable to that of exogenous insulin with the advantages of cured pancreas and restored islets not attained by insulin.

Cell mediated ECM-degradation as an emerging tool for anti-fibrotic strategy

Investigation into the role of cells with respect to extracellular matrix (ECM) remodeling is still in its infancy. Particularly, ECM degradation is an indispensable process during the recovery from fibrosis. Cells with ECM degradation ability due to the secretion of various matrix metalloproteinases (MMPs) have emerged as novel contributors to the treatment of fibrotic diseases. In this review, we focus on the ECM degradation ability of cells associated with the repertoire of MMPs that facilitate the attenuation of fibrosis through the inhibition of ECM deposition. Besides, innovative approaches to engineering and characterizing cells with degradation ability, as well as elucidating the mechanism of the ECM degradation, are also illustrated. Studies conducted to date on the use of cell-based degradation for therapeutic purposes to combat fibrosis are summarized. Finally, we discuss the therapeutic potential of cells with high degradation ability, hoping to bridge the gap between benchside research and bedside applications in treating fibrotic diseases.

Advance of Mesenchymal Stem Cells in Chronic End-Stage Liver Disease Control

The chronic liver diseases will slowly develop into liver fibrosis, cirrhosis, and even liver cancer if no proper control is performed with high efficiency. Up to now, the most effective treatment for end-stage liver diseases is liver transplantation. However, liver transplantation has the problems of donor deficiency, low matching rate, surgical complications, high cost, and immune rejection. These problems indicate that novel therapeutic strategies are urgently required. Mesenchymal stem cells (MSCs) are somatic stem cells with multidirectional differentiation potential and self-renewal ability. MSCs can secrete a large number of cytokines, chemokines, immunomodulatory molecules, and hepatotrophic factors, as well as produce extracellular vesicles. They alleviate liver diseases by differentiating to hepatocyte-like cells, immunomodulation, homing to the injured site, regulating cell ferroptosis, regulating cell autophagy, paracrine effects, and MSC-mitochondrial transfer. In this review, we focus on the main resources of MSCs, underlying therapeutic mechanisms, clinical applications, and efforts made to improve MSC-based cell therapy efficiency.

Rho-kinase inhibition ameliorates non-alcoholic fatty liver disease in type 2 diabetic rats

Non-alcoholic fatty liver disease (NAFLD) is linked to type 2 diabetes mellitus (T2DM), obesity, and insulin resistance. The Rho/ROCK pathway had been involved in the pathophysiology of diabetic complications. This study was designed to assess the possible protective impacts of the Rho/Rho-associated coiled-coil containing protein kinase (Rho/ROCK) inhibitor fasudil against NAFLD in T2DM rats trying to elucidate the underlying mechanisms. Animals were assigned into control rats, non-treated diabetic rats with NAFLD, and diabetic rats with NAFLD that received fasudil treatment (10 mg/kg per day) for 6 weeks. The anthropometric measures and biochemical analyses were performed to assess metabolic and liver function changes. The inflammatory and oxidative stress markers and the histopathology of rat liver tissues were also investigated. Groups with T2DM showed increased body weight, serum glucose, and insulin resistance. They exhibited disturbed lipid profile, enhancement of inflammatory cytokines, and deterioration of liver function. Fasudil administration reduced body weight, insulin resistance, and raised liver enzymes. It improved the disturbed lipid profile and attenuated liver inflammation. Moreover, it slowed down the progression of high fat diet (HFD)-induced liver injury and reduced the caspase-3 expression. The present study demonstrated beneficial amelioration effect of fasudil on NAFLD in T2DM. The mechanisms underlying these impacts are improving dyslipidemia, attenuating oxidative stress, downregulated inflammation, improving mitochondrial architecture, and inhibiting apoptosis.

α-Lipoic Acid Protects against Cyclosporine A-Induced Hepatic Toxicity in Rats: Effect on Oxidative Stress, Inflammation, and Apoptosis

The clinical application of cyclosporine A (CsA) as an immunosuppressive agent is limited by its organ toxicity. We aimed to evaluate the effectiveness of α-lipoic acid against CsA-induced hepatotoxicity and to delineate the underlying molecular mechanisms. Male Wistar rats (n = 24, 8 per each group) received the vehicle, CsA (25 mg/kg) and/or ALA (100 mg/kg, p.o.) for 3 weeks. Biochemical markers of liver function (serum ALT, AST, ALP < GGT), oxidative stress (MDA, TAC, SOD, GSH, Nrf2/HO-1), inflammation (NF-κB, CD68, iNOS, NO, COX-2), and apoptosis (caspase-3) were assessed in serum and tissue. Liver histological analysis using H&E and Sirius red was performed. The development of liver injury in CsA-treated animals was indicated by elevated levels of liver enzymes, oxidants/antioxidants imbalance, inflammatory cells infiltration, up-regulated expression of inflammatory mediators, and apoptosis. These changes were associated with altered architecture of hepatic cells and fibrous connective tissue. ALA co-administration protected against CsA-induced liver damage and ameliorated biochemical changes and cellular injury. In conclusion, ALA demonstrated hepatoprotective potential against CsA-induced liver injury through combating oxidative stress, inflammation, and apoptosis, highlighting ALA as a valuable adjunct to CsA therapy.

Combined effect of hydrogen sulfide and mesenchymal stem cells on mitigating liver fibrosis induced by bile duct ligation: Role of anti-inflammatory, anti-oxidant, anti-apoptotic, and anti-fibrotic biomarkers

OBJECTIVES

Liver fibrosis eventually develops into cirrhosis and hepatic failure, which can only be treated with liver transplantation. We aimed to assess the potential role of hydrogen sulfide (H₂S) alone and combined with bone marrow-derived mesenchymal stem cells (BM-MSCs) on hepatic fibrosis induced by bile-duct ligation (BDL) and to compare their effects to silymarin.

MATERIALS AND METHODS

Alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TB), and alkaline phosphatase (ALP) were investigated in serum. Gene expression levels of CBS (cystathionine β-synthase), CSE (cystathionine γ-lyase), and alpha-smooth muscle actin (α- SMA) were measured in liver tissues using RT-PCR. Hepatic protein kinase (Akt) was assessed by Western blot assay. Liver oxidative stress markers, malondialdehyde (MDA), and reduced glutathione (GSH) were analyzed by the colorimetric method. Lipocalin-2 (LCN2) and transforming growth factor-β (TGF-β) were measured using ELIZA. Liver tissues were examined by H&E and Masson trichome staining for detection of liver necrosis or fibrosis. Caspase 3 expression was evaluated by immunohistochemistry.

RESULTS

H₂S and BM-MSCs ameliorated liver function and inhibited inflammation and oxidative stress detected by significantly decreased serum ALT, AST, ALP, TB, and hepatic MDA, Akt, TGF-β, LCN2, and α-SMA expression and significantly increased CBS and CSE gene expression levels. They attenuated hepatic apoptosis evidenced by decreased hepatic caspase expression.

CONCLUSION

Combined treatment with H₂S and BM-MSCs could attenuate liver fibrosis induced by BDL through mechanisms such as anti-inflammation, anti-oxidation, anti-apoptosis, anti-fibrosis, and regenerative properties indicating that using H₂S and MSCs may represent a promising approach for management of cholestatic liver fibrosis.

Vanillin augments liver regeneration effectively in Thioacetamide induced liver fibrosis rat model

AIMS

This study has been designed to investigate the role of vanillin either as prophylaxis or treatment in liver regeneration augmentation and liver fibrosis regression in thioacetamide (TAA) induced liver damage.

MATERIALS AND METHODS

Animals were injected with TAA to induce liver injury (200mg/kg twice weekly) for 8 weeks. In vanillin prophylaxis group; rats were administered vanillin (100 mg/Kg; IP, daily) from day 1 of TAA injection for 8 weeks. In vanillin treatment group; rats were confronted with the same dose of TAA injection for 8 weeks then treated with vanillin (100 mg/Kg, IP, daily) for 4 weeks. ALT, AST activities, serum albumin, hepatic GSH, MDA, HGF, VEGF, IL-6 and TNF-α levels were measured and also, MMP-2, TIMP-1 and cyclin D gene expression were determined. Liver sections were stained with H&E and Sirius red and immunostained for Ki-67 and α-SMA for histological and immunohistological changes analysis.

KEY FINDINGS

Vanillin improved liver function and histology. Also, showed a remarkable increase in hepatic HGF and VEGF level, and up-regulation of cyclin D1 expression accompanied by a significant up-regulation of MMP-2 and down- regulation of TIMP-1. All these effects were accompanied by TNF-α, IL-6 and oxidative stress significant attenuation.

SIGNIFICANCE

In conclusion, vanillin enhanced liver regeneration in TAA induced liver damage model; targeting growth factors (HGF, VEGF) and cellular proliferation marker cyclin D1. As well as stimulating fibrosis regression by inhibition of ECM accumulation and enhancing its degradation.

SOD2 overexpression in bone marrow‑derived mesenchymal stem cells ameliorates hepatic ischemia/reperfusion injury

Hepatic ischemia/reperfusion injury (HIRI) is a complex pathophysiological process that may develop after liver transplantation and resection surgery, as well as in uncontrolled clinical conditions. Bone marrow‑derived mesenchymal stem cells (BM‑MSCs) are potential targets for liver diseases. Thus, the present study aimed to investigate the effects of superoxide dismutase 2 (SOD2) overexpression in BM‑MSCs on HIRI by constructing a HIRI rat model. The adenoviral vector containing SOD2 and the corresponding control vector were designed and constructed, and SOD2‑overexpressing BM‑MSCs were injected into the tail vein of the rats. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, as well as pathological changes and the remnant liver regeneration rate were determined. The activities of SOD and glutathione peroxidase (GSH‑Px), and malondialdehyde (MDA) content were measured. Reactive oxygen species (ROS) were determined with 2',7'‑-dichlorofluorescein diacetate and measured via fluorescence microscopy. Cell apoptosis was assessed using TUNEL staining. Moreover, the expression levels of Bax, Bcl‑2 and caspase‑3 were detected via western blotting. SOD2‑overexpressing BM‑MSCs significantly reduced the elevation of serum AST and ALT levels. Furthermore, SOD2‑overexpressing BM‑MSCs enhanced SOD and GSH‑Px activities, and suppressed the production of MDA and ROS. Histopathological findings revealed that SOD2‑overexpressing BM‑MSCs decreased the number of TUNEL‑positive cells in the liver. It was also found that SOD2‑overexpressing BM‑MSCs promoted Bcl‑2 expression, but inhibited Bax and caspase‑3 expression in HIRI. Collectively, these findings suggest that SOD2‑overexpressing BM‑MSCs may provide therapeutic support in HIRI by inhibiting oxidative stress and hepatocyte apoptosis.

Current and Emerging Approaches for Hepatic Fibrosis Treatment

Liver fibrosis resulting from chronic liver injury is a key factor to develop liver cirrhosis and risk of hepatocellular carcinoma (HCC) which are major health burden worldwide. Therefore, it is necessary for antifibrotic therapies to prevent chronic liver disease progression and HCC development. There has been tremendous progress in understanding the mechanisms of liver fibrosis in the last decade, which has created new opportunities for the treatment of this condition. In this review, we aim to make an overview on information of different potential therapies (drug treatment, cell therapy, and liver transplantation) for the liver fibrosis and hope to provide the therapeutic options available for the treatment of liver fibrosis and discuss novel approaches.

Genetically-Modified Stem Cell in Regenerative Medicine and Cancer Therapy; A New Era

Recently, genetic engineering by various strategies to stimulate gene expression in a specific and controllable mode is a speedily growing therapeutic approach. Genetic modification of human stem or progenitor cells, such as embryonic stem cells (ESCs), neural progenitor cells (NPCs), mesenchymal stem/stromal cells (MSCs), and hematopoietic stem cells (HSCs) for direct delivery of specific therapeutic molecules or genes has been evidenced as an opportune plan in the context of regenerative medicine due to their supported viability, proliferative features, and metabolic qualities. On the other hand, a large number of studies have investigated the efficacy of modified stem cells in cancer therapy using cells from various sources, disparate transfection means for gene delivery, different transfected yields, and wide variability of tumor models. Accordingly, cell-based gene therapy holds substantial aptitude for the treatment of human malignancy as it could relieve signs or even cure cancer succeeding expression of therapeutic or suicide transgene products; however, there exist inconsistent results in this regard. Herein, we deliver a brief overview of stem cell potential to use in cancer therapy and regenerative medicine and importantly discuss stem cells based gene delivery competencies to stimulate tissue repair and replacement in concomitant with their potential to use as an anti-cancer therapeutic strategy, focusing on the last two decades in vivo studies.

Schwann cells promote prevascularization and osteogenesis of tissue-engineered bone via bone marrow mesenchymal stem cell-derived endothelial cells

Background

Tissue-engineered bone grafts (TEBGs) that undergo vascularization and neurotization evolve into functioning bone tissue. Previously, we verified that implanting sensory nerve tracts into TEBGs promoted osteogenesis. However, the precise mechanisms and interaction between seed cells were not explored. In this study, we hypothesized that neurotization may influence the osteogenesis of TEBGs through vascularization.

Methods

We cultured rat Schwann cells (SCs), aortic endothelial cells (AECs), and bone marrow-derived mesenchymal stem cells (BM-MSCs) and then obtained BM-MSC-derived induced endothelial cells (IECs) and induced osteoblasts (IOBs). IECs and AECs were cultured in an SC-conditioned medium (SC-CM) to assess proliferation, migration, capillary-like tube formation, and angiogenesis, and the vascular endothelial growth factor (VEGF) levels in the supernatants were detected. We established an indirect coculture model to detect the expression of nestin and VEGF receptors in IECs and tissue inhibitor of metalloproteinase (TIMP)-2 in SCs. Then, SCs, IECs, and IOBs were labeled and loaded into a β-tricalcium phosphate scaffold to induce prevascularization, and the scaffold was implanted into a 6-mm-long defect of rat femurs. Three groups were set up according to the loaded cells: I, SCs, and IECs (coculture for 3 days) plus IOBs; II, IECs (culture for 3 days) plus IOBs; III, IOBs. Nestin and TIMP-2 expression and osteogenesis of TEBGs were evaluated at 12 weeks post-implantation through histological and radiological assessments.

Results

We found that SC-CM promoted IEC proliferation, migration, capillary-like tube formation, and angiogenesis, but no similar effects were observed for AECs. IECs expressed nestin extensively, while AECs barely expressed nestin, and SC-CM promoted the VEGF secretion of IECs. In the coculture model, SCs promoted nestin and VEGF receptor expression in IECs, and IECs inhibited TIMP-2 expression in SCs. The promotion of prevascularized TEBGs by SCs and IECs in group I augmented new bone formation at 6 and 12 weeks. Nestin expression was higher in group I than in the other groups, while TIMP-2 expression was lower at 12 weeks.

Conclusions

This study demonstrated that SCs can promote TEBG osteogenesis via IECs and further revealed the related specific characteristics of IECs, providing preliminary cytological evidence for neurotization of TEBGs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02433-3.

The efficacy of bone marrow-derived mesenchymal stem cells and/or erythropoietin in ameliorating kidney damage in gamma irradiated rats: Role of non-hematopoietic erythropoietin anti-apoptotic signaling

Radiation-induced multiple organ injury, including γ-radiation nephropathy, is the most common. Even with dose fractionation strategy, residual late side effects are inevitable. Bone marrow-derived mesenchymal stem cells (BM-MSCs) transplantation and erythropoietin (EPO) have shown to be effective in treating chronic kidney disease and associated anemia. This study aimed to evaluate the effect of BM-MSCs and/or EPO in fractionated γ-irradiation induced kidney damage in rats. Adult male Wistar rats were randomized into 2 groups; normal and 8 Gy (fractionated dose of 2 Gy for 4 days) γ-irradiated rats. Animal from both groups were subdivided to receive the following treatments: BM-MSCs (1 × 10⁶ cells/rat, i.v - once), EPO (100 IU/kg, i.p - every other day for 30 days) or their combined treatment (BM-MSCs and EPO). γ-Irradiated rats showed a noticeable elevation in serum urea and creatinine, kidney malondialdehyde (MDA) and caspase 3 activity. They also revealed significant drop in kidney glutathione (GSH) and Bcl2 protein contents. Conspicuously, they revealed down-regulation of renal EPO signaling (EPO, EPOR, pJAK2, pPI3K and pAkt). Conversely, groups treated with BM-MSCs and/or EPO revealed significant modulation in most tested parameters and appeared to be effective in minimizing the hazard effects of radiation. In conclusion, BM-MSCs and/or EPO exhibited therapeutic potentials against nephrotoxicity induced by fractionated dose of γ-irradiation. An effect mediated by antioxidant and non-hematopoietic EPO downstream anti-apoptotic signaling (PI3K/Akt) pathway. EPO potentiate the repair capabilities of BM-MSCs making this combined treatment a promising therapeutic strategy to overcome radiotherapy-induced kidney damage.

Platelets Boost Recruitment of CD133+ Bone Marrow Stem Cells to Endothelium and the Rodent Liver-The Role of P-Selectin/PSGL-1 Interactions

We previously demonstrated that clinical administration of mobilized CD133⁺ bone marrow stem cells (BMSC) accelerates hepatic regeneration. Here, we investigated the potential of platelets to modulate CD133⁺BMSC homing to hepatic endothelial cells and sequestration to warm ischemic livers. Modulatory effects of platelets on the adhesion of CD133⁺BMSC to human and mouse liver-sinusoidal- and micro- endothelial cells (EC) respectively were evaluated in in vitro co-culture systems. CD133⁺BMSC adhesion to all types of EC were increased in the presence of platelets under shear stress. This platelet effect was mostly diminished by antagonization of P-selectin and its ligand P-Selectin-Glyco-Ligand-1 (PSGL-1). Inhibition of PECAM-1 as well as SDF-1 receptor CXCR4 had no such effect. In a model of the isolated reperfused rat liver subsequent to warm ischemia, the co-infusion of platelets augmented CD133⁺BMSC homing to the injured liver with heightened transmigration towards the extra sinusoidal space when compared to perfusion conditions without platelets. Extravascular co-localization of CD133⁺BMSC with hepatocytes was confirmed by confocal microscopy. We demonstrated an enhancing effect of platelets on CD133⁺BMSC homing to and transmigrating along hepatic EC putatively depending on PSGL-1 and P-selectin. Our insights suggest a new mechanism of platelets to augment stem cell dependent hepatic repair.

Mesenchymal stromal cells; a new horizon in regenerative medicine

In recent decades, mesenchymal stromal cells (MSCs) biomedical utilizing has attracted worldwide growing attention. After the first report of the human MSCs obtaining from the bone marrow (BM) tissue, these cells were isolated from wide types of the other tissues, ranging from adipose tissue to dental pulp. Their specific characteristics, comprising self-renewality, multipotency, and availability accompanied by their immunomodulatory properties and little ethical concern denote their importance in the context of regenerative medicine. Considering preclinical studies, MSCs can modify immune reactions during tissue repair and restoration, providing suitable milieu for tissue recovery; on the other hand, they can be differentiated into comprehensive types of the body cells, such as osteoblast, chondrocyte, hepatocyte, cardiomyocyte, fibroblast, and neural cells. Though a large number of studies have investigated MSCs capacities in regenerative medicine in varied animal models, the oncogenic capability of unregulated MSCs differentiation must be more assessed to enable their application in the clinic. In the current review, we provide a brief overview of MSCs sources, isolation, and expansion as well as immunomodulatory activities. More important, we try to collect and discuss recent preclinical and clinical research and evaluate current challenges in the context of the MSC-based cell therapy for regenerative medicine.

Therapeutic effect of bone marrow mesenchymal stem cells in a rat model of carbon tetrachloride induced liver fibrosis

Background

Liver fibrosis is a major medical problem with high mortality and morbidity rates where the formation of regenerative nodules and cirrhosis leads to loss of liver function and may result in the development of hepatocellular carcinoma. bone marrow mesenchymal stem cells (BM-MSCs) have drawn attention as a novel approach for treatment of liver fibrosis. This study aimed to evaluate the therapeutic effect of BM-MSCs on the liver structure in carbon tetrachloride (CCl₄) induced liver fibrosis in male rats relative to resveratrol and Silybum marianum as standard drugs derived from herbal plants.

Methods

Fifty adult male albino rats (Sprague Dawley strain; 180–220 g mean body weight) were purchased from the Laboratory Animal Unit in the Nile Center of Experimental Research, Mansoura, Egypt. Liver function were determined, isolation and preparation of BM- MSCs and detection of cell-surface markers by flow cytometry.

Results

Animals exposed to CCl₄ developed liver injury characterized by significant increase of liver enzymes, malondialdehyde (MDA), tumor necrosis factor alpha (TNFα), and CYP450, inhibition of antioxidant enzymes, and decreased albumin. Treatment with stem cells enhanced liver state more effectively than resveratrol and S. marianum. It significantly decreased AST, ALT, ALP, MDA, TNF-α, and CYP450 and increased albumin, SOD, GSH, GST, and CAT. Histopathological study and atomic force microscope results confirmed the therapeutic effects of MSCs.

Conclusions

BM-MSCs could restore liver structure and function in CCL₄ induced liver fibrosis rat model, ameliorating the toxicity of CCl₄ and improving liver function tests.

Mechanisms Underlying Cell Therapy in Liver Fibrosis: An Overview

Fibrosis is a common feature in most pathogenetic processes in the liver, and usually results from a chronic insult that depletes the regenerative capacity of hepatocytes and activates multiple inflammatory pathways, recruiting resident and circulating immune cells, endothelial cells, non-parenchymal hepatic stellate cells, and fibroblasts, which become activated and lead to excessive extracellular matrix accumulation. The ongoing development of liver fibrosis results in a clinically silent and progressive loss of hepatocyte function, demanding the constant need for liver transplantation in clinical practice, and motivating the search for other treatments as the chances of obtaining compatible viable livers become scarcer. Although initially cell therapy has emerged as a plausible alternative to organ transplantation, many factors still challenge the establishment of this technique as a main or even additional therapeutic tool. Herein, the authors discuss the most recent advances and point out the corners and some controversies over several protocols and models that have shown promising results as potential candidates for cell therapy for liver fibrosis, presenting the respective mechanisms proposed for liver regeneration in each case.

Adipose-Derived Tissue in the Treatment of Dermal Fibrosis: Antifibrotic Effects of Adipose-Derived Stem Cells

Treatment of hypertrophic scars and other fibrotic skin conditions with autologous fat injections shows promising clinical results; however, the underlying mechanisms of its antifibrotic action have not been comprehensively studied. Adipose-derived stem cells, or stromal cell-derived factors, inherent components of the transplanted fat tissue, seem to be responsible for its therapeutic effects on difficult scars. The mechanisms by which this therapeutic effect takes place are diverse and are mostly mediated by paracrine signaling, which switches on various antifibrotic molecular pathways, modulates the activity of the central profibrotic transforming growth factor β/Smad pathway, and normalizes functioning of fibroblasts and keratinocytes in the recipient site. Direct cell-to-cell communications and differentiation of cell types may also play a positive role in scar treatment, even though they have not been extensively studied in this context. A more thorough understanding of the fat tissue antifibrotic mechanisms of action will turn this treatment from an anecdotal remedy to a more controlled, timely administered technology.

BMSCs protect against liver injury via suppressing hepatocyte apoptosis and activating TGF-β1/Bax singling pathway

Many factors cause liver injury, including chronic consumption of alcohol, irregular use of drugs, excessive levels of arsenic in water. This study aims to investigate role of bone marrow-derived mesenchymal stem cells (BMSCs) in liver injury recovery and to explore mechanism. BMSCs and primary hepatocytes were isolated, cultured and identified. Hepatocyte model and hepatic fibrosis (HF) model were established using carbon tetrachloride (CCL-4). The role of BMSCs were investigated in both in vitro and in vivo levels. Cell proliferation was examined using MTT assay. Transforming growth factor-β1 (TGF-β1), Bcl-2 and Bax expression were detected using western blot and real-time PCR, respectively. Results indicated that BMSCs and primary hepatocytes were successfully isolated and identified, and hepatocyte model was successfully established. BMSCs and HGF treatment enhance viability of normal hepatocytes and hepatocyte injury model. Cell viability in BMSCs treatment and Bax-1 inhibitor treatment group was higher significantly compared to normal hepatocyte control and injury hepatocyte model, respectively (P<0.05). Bax-1 expression was significantly lower and Bcl-2 was significantly higher in Bax-1 inhibitor treatment and BMSCs treatment group compared to normal hepatocyte control (normal rats) and injury hepatocyte model (HF model), respectively (P<0.05). BMSCs significantly decreased ALT and AST levels compared to Saline group (P<0.05). In conclusion, function of BMSCs in liver injury was triggered by inhibiting hepatocyte apoptosis and leading cell proliferation through TGF-β1/Bax singling pathway. Our study proved protective role of BMSCs against liver injury via TGF-β1/Bax pathway, which would enrich application of BMSC in clinical.

Liver fibrosis alleviation after co-transplantation of hematopoietic stem cells with mesenchymal stem cells in patients with thalassemia major

The aims of this study are to determine the replacement rate of damaged hepatocytes by donor-derived cells in sex-mismatched recipient patients with thalassemia major and to determine whether co-transplantation of mesenchymal stem cells and hematopoietic stem cells (HSCs) can alleviate liver fibrosis. Ten sex-mismatched donor-recipient pairs who received co-transplantation of HSCs with mesenchymal stem cells were included in our study. Liver biopsy was performed before transplantation. Two other liver biopsies were performed between 2 and 5 years after transplantation. The specimens were studied for the presence of donor-derived epithelial cells or hepatocytes using fluorescence in situ hybridization by X- and Y-centromeric probes and immunohistochemical staining for pancytokeratin, CD45, and a hepatocyte-specific antigen. All sex-mismatched tissue samples demonstrated donor-derived hepatocyte independent of donor gender. XY-positive epithelial cells or hepatocytes accounted for 11 to 25% of the cells in histologic sections of female recipients in the first follow-up. It rose to 47-95% in the second follow-up. Although not statistically significant, four out of ten patients showed signs of improvement in liver fibrosis. Our results showed that co-transplantation of HSC with mesenchymal stem cells increases the rate of replacement of recipient hepatocytes by donor-derived cells and may improve liver fibrosis.

In vitro and in vivo study of the application of volvox spheres to co-culture vehicles in liver tissue engineering

Volvox sphere is a biomimetic concept of a natural Volvox, wherein a large outer sphere contains smaller inner spheres, which can encapsulate cells and provide a double-layer three-dimensional environment for culturing cells. This study simultaneously encapsulated rat mesenchymal stem cells (MSCs) and AML12 hepatocytes in volvox spheres and extensively evaluated the effects of various culturing modes on cell functions and fates. The results showed that compared with a static flask culture, MSCs encapsulated in volvox spheres differentiated into hepatocyte-like cells with a 2-fold increase in albumin (ALB) expression and a 2.5-fold increase in cytokeratin 18 expression in a dynamic bioreactor. Moreover, the restorative effects of volvox spheres encapsulating cells on retrorsine-exposed CCl₄-induced liver injuries in rats were evaluated. The data presented significant reductions in AST and ALT levels after the implantation of volvox spheres encapsulating both MSCs and AML12 hepatocytes in vivo. In contrast to the negative control group, histopathological analysis demonstrated liver repair and formation of the new liver tissue in groups implanted with volvox spheres containing cells. These results demonstrate that liver cells implanted with volvox spheres encapsulating both MSCs and AML12 hepatocytes promote liver repair and liver tissue regeneration in liver failure caused by necrotizing agents such as retrorsine and CCl₄. Hence, volvox spheres encapsulating MSCs and liver cells can be a promising and clinically effective therapy for liver injury.

STATEMENT OF SIGNIFICANCE

In this study, we used a volvox sphere, which is a unique design that mimics the natural Volvox, that consists of a large outer sphere that contains smaller inner spheres, which provide a three-dimensional environment to culture cells. The purpose of this study is to co-culture mesenchymal stem cells (MSCs) and AML12 liver cells in volvox spheres and evaluate two different culture methods, dynamic bioreactor and static culture flask,on the cultured cells. In addition, we aimed to evaluate the restorative effects of volvox spheres encapsulating MSCs and/or AML12 liver cells on rats with retrorsine-exposed CCl₄-induced liver injuries. The results showed that MSCs encapsulated in volvox spheres differentiated into hepatocyte-like cells with a 2-fold increase in albumin expression and a 2.5-fold increase in cytokeratin 18 expression ina dynamic bioreactor. Moreover, the data presented significant reductions in AST and ALT levels after the implantation of volvox spheres encapsulating both MSCs and AML12 hepatocytes in vivo. In contrast to the negative control group, histopathological analysis demonstrated liver repair and formation of new liver tissue in groups implanted with volvox spheres containing cells. These results demonstrate that liver cells implanted with volvox spheres encapsulating both MSCs and AML12 hepatocytes promote liver repair and liver tissue regeneration in liver failure caused by necrotizing agents such as retrorsine and CCl₄. Hence, volvox spheres encapsulating MSCs and liver cells can be a promising and clinically effective therapy for liver injury.

Mammalian MSC from selected species: Features and applications

Mesenchymal stromal/stem cells (MSC) are promising candidates for cellular therapy of different diseases in humans and in animals. Following the guidelines of the International Society for Cell Therapy, human MSC may be identified by expression of a specific panel of cell surface markers (CD105+, CD73+, CD90+, CD34-, CD14-, or CD11b-, CD79- or CD19-, HLA-DR-). In addition, multiple differentiation potential into at least the osteogenic, adipogenic, and chondrogenic lineage is a main criterion for MSC definition. Human MSC and MSC of a variety of mammals isolated from different tissues meet these criteria. In addition to the abovementioned, they express many more cell surface markers. Yet, these are not uniquely expressed by MSC. The gross phenotypic appearance like marker expression and differentiation potential is similar albeit not identical for MSC from different tissues and species. Similarly, MSC may feature different biological characteristics depending on the tissue source and the isolation and culture procedures. Their versatile biological qualities comprising immunomodulatory, anti-inflammatory, and proregenerative capacities rely largely on the migratory and secretory capabilities of MSC. They are attracted to sites of tissue lesion and secrete factors to promote self-repair of the injured tissue. This is a big perspective for clinical MSC applications in both veterinary and human medicine. Phase I/II clinical trials have been initiated to assess safety and feasibility of MSC therapies in acute and chronic disease settings. Yet, since the mode of MSC action in a specific disease environment is still unknown at large, it is mandatory to unravel the response of MSC from a given source onto a specific disease environment in suitable animal models prior to clinical applications. © 2017 International Society for Advancement of Cytometry.

Silymarin-loaded Eudragit(®) RS100 nanoparticles improved the ability of silymarin to resolve hepatic fibrosis in bile duct ligated rats

Some nano-formulations of silymarin (SM), a drug commonly used for liver diseases, were developed to overcome its poor solubility and poor bioavailability; antifibrotic effect of these formulations has not been tested yet. In this study we aimed to formulate and evaluate silymarin-loaded Eudragit(®) RS100 nanoparticles (SMnps) and to test the capability of SMnps to reverse an established fibrosis model. SMnps were prepared by solvent evaporation and nano-precipitation techniques. The influence of drug:polymer ratio, concentration of surfactant in the aqueous phase on particle size, drug entrapment efficiency (EE) % and in vitro drug releases were investigated. For in vivo evaluation, bile duct ligated (BDL)-rats were treated with either SM or SMnps every other day (125mg/kg) orally for 3 weeks started 3 weeks after BDL. Liver function tests, oxidative stress and fibrosis/fibrogenesis process were evaluated using biochemical and histopathological techniques. The formulation No (F4) of SMnps showed an average particle size of 632.28±12.15nm, a drug EE% of 89.47±1.65% and released the drug in a prolonged manner over 24h. The prepared SMnps were nearly spherical with smooth surfaces. In BDL-rats, treatments with either SM or SMnps corrected liver function and oxidative stress. Only SMnps was able to reverse the induced fibrosis; SMnps significantly decreased serum tumor necrosis factor- α (TNF-α), serum transforming growth factor- β1 (TGF-β1), hepatic hydroxyproline and downregulated the hepatic expression of tissue inhibitor metalloproteinase-1 (TIMP-1) and cytokeratin-19 (CK-19), whilst increased hepatic hepatocytes growth factor (HGF) and upregulated the hepatic expression of matrix metalloproteinase-2 (MMP-2) and increased MMP-2/TIMP-1 ratio at mRNA level. Livers of rats treated with SMnps showed very little collagen in ECM and restored hepatic architecture as compared to either BDL rats or rats treated with SM.

CONCLUSION

Formulation of silymarin as nanoparticles improved its ability to resolve cholestasis-induced liver fibrosis by restoring hepatic regenerative capabilities. Therefore, formulation of SMnps may represent a step forward in the field of anti-fibrotic drug development.