Potential application for mesenchymal stem cells in the treatment of cardiovascular diseases

Human bone marrow mesenchymal stem cell-derived hepatocytes improve the mouse liver after acute acetaminophen intoxication by preventing progress of injury

Mesenchymal stem cells from human bone marrow (hMSC) have the potential to differentiate into hepatocyte-like cells in vitro and continue to maintain important hepatocyte functions in vivo after transplantation into host mouse livers. Here, hMSC were differentiated into hepatocyte-like cells in vitro (hMSC-HC) and transplanted into livers of immunodeficient Pfp/Rag2⁻/⁻ mice treated with a sublethal dose of acetaminophen (APAP) to induce acute liver injury. APAP induced a time- and dose-dependent damage of perivenous areas of the liver lobule. Serum levels of aspartate aminotransferase (AST) increased to similar levels irrespective of hMSC-HC transplantation. Yet, hMSC-HC resided in the damaged perivenous areas of the liver lobules short-term preventing apoptosis and thus progress of organ destruction. Disturbance of metabolic protein expression was lower in the livers receiving hMSC-HC. Seven weeks after APAP treatment, hepatic injury had completely recovered in groups both with and without hMSC-HC. Clusters of transplanted cells appeared predominantly in the periportal portion of the liver lobule and secreted human albumin featuring a prominent quality of differentiated hepatocytes. Thus, hMSC-HC attenuated the inflammatory response and supported liver regeneration after acute injury induced by acetaminophen. They hence may serve as a novel source of hepatocyte-like cells suitable for cell therapy of acute liver diseases.

Differentiation and migration of bone marrow mesenchymal stem cells transplanted through the spleen in rats with portal hypertension

Aims

The goals of this paper were to evaluate the differentiation of bone marrow mesenchymal stem cells (BMSCs) into hepatocyte-like cells invitro, and to determine whether stem cells can migrate and plant into the liver with portal hypertension accompanied by the end-stage of liver disease.

Methods

BMSCs were isolated from rats and amplified with hepatocyte growth factor (HGF) and fibroblast growth factor-4 (FGF-4). The expression of alpha-fetoprotein (AFP), cytokeratin 18 (CK-18), and albumin (ALB) was detected by immunofluorescence in induced cells. Rats were randomly divided into experimental (with common bile duct ligation) and control groups. After injection of fluorescence labeled cells, cell distribution was observed under a fluorescence microscope. The integrated optical density (IOD) and cell distribution scores were evaluated using Image-Pro Plus 6.0 software. The portal pressure was measured before the rats were killed.

Results

After being induced with HGF and FGF-4, the Golgi apparatus, endoplasmic reticulum, ribosomes, and mitochondria all significantly increased in the fifth generation cells. Immunofluorescent analysis showed that the induced cells expressed AFP, CK-18, and ALB. BMSCs were stained by CM-Dil, and the labeling rate was as high as 95.5%. The portal pressure in experimental group was much higher than that of the control group (18.04±2.35 vs. 9.75±1.40cm H₂O p<0.01). The IOD of transplanted cells in the experimental group was also significantly higher than that of the control group (11.30±2.09×10⁵ vs. 2.93±0.88×10⁵, p<0.01). In addition, the cell distribution score in the experimental group was lower than that of the control group (1.99±0.36 vs. 2.36±0.27, P<0.05).

Conclusions

The combination of HGF and FGF-4 induces the differentiation of BMSCs into hepatocyte-like cells, which express AFP, CK-18, and ALB. In addition, the recruitment of BMSCs (after transplantation in the spleen) was improved in rats with portal hypertension.

Autologous bone marrow cell infusions suppress tumor initiation in hepatocarcinogenic mice with liver cirrhosis

We have previously reported the efficacy and safety of autologous bone marrow cell infusion (ABMi) therapy for liver cirrhosis patients without hepatocellular carcinoma in a multicenter clinical trial. However, since liver cirrhosis is highly oncogenic, evaluation of the effects of ABMi on the mechanisms of hepatocarcinogenesis is of great importance. Therefore, frequent ABMi was performed in hepatocarcinogenic mice, and its effects on hepatocarcinogenesis were analyzed. The N-nitrosodiethylamine (DEN)/green fluorescent protein (GFP)-carbon tetrachloride (CCl(4) ) model was developed by administering DEN once, followed by repeated administration of CCl(4) intraperitoneally as for the control group. In the administration (ABMi) group, GFP-positive bone marrow cells were infused through a tail vein. The kinetics of hepatocarcinogenesis were evaluated histologically 4.5 months after DEN treatment. At 4.5 months, there was significantly lower incidence of foci and tumors in the ABMi group, and they were smaller in number, while their size was almost equal. No GFP-positive tumors were found in ABMi livers. Moreover, ABMi livers showed significantly reduced liver fibrosis, consistent with significantly lower 8-hydroxy-2'-deoxyguanosine levels, higher superoxide dismutase activity, and increased nuclear translocation of nuclear factor-erythroid 2 p45-related factor 2. These results demonstrate that frequent ABMi might contribute to suppressed tumor initiation during stages of hepatocarcinogenesis, consistent with improvements in liver fibrosis and stabilization of redox homeostasis.

Stem cells in liver failure

Orthotopic liver transplantation (OLT) represents the only reliable therapeutic approach for acute liver failure (ALF), liver failure associated to end-stage chronic liver diseases (CLD) and non-metastatic liver cancer. The clinical impact of liver failure is relevant because of the still high ALF mortality and the increasing worldwide prevalence of cirrhosis that, in turn, is the main predisposing cause for hepatocellular carcinoma (HCC). Moreover, in the next decade because an increased number of patients reaching end-stage disease and requiring OLT may face a shortage of donor livers. This clinical scenario led several laboratories to explore the feasibility and efficiency of alternative approaches, involving cellular therapy, to counteract liver failure. The present chapter overviews results and concepts emerged from recent experimental and clinical studies in which adult or embryonic hepatocytes, hepatic stem/progenitor cells, induced pluripotent stem (iPS) cells as well as extrahepatic stem cells have been used as putative transplantable cell sources.

Chondrogenesis from umbilical cord blood cells stimulated with BMP-2 and BMP-6

Umbilical cord blood contains undifferentiated mesenchymal stem cells (MSCs) with chondrogenic potential that may be used for the repair of joint damage. The role of growth factors during the process of chondrogenesis is still not entirely understood. The objective of this study was to evaluate the formation of chondrocytes, cartilaginous matrix and type II collagen from human umbilical cord blood stem cells exposed to two different growth factors, BMP-6 and BMP-2, while being cultured as a micromass or a monolayer. Umbilical cord blood was obtained from full-term deliveries, and then, mononuclear cells were separated and cultured for expansion. Afterward, these cells were evaluated by flow cytometry using antibodies specific for MSCs and induced to chondrogenic differentiation in micromass and monolayer cultures supplemented with BMP-2 and BMP-6. Cellular phenotype was evaluated after 7, 14 and 21 days by RT-PCR and Western blot analysis to identify the type II collagen and aggrecan. The expanded cells displayed surface antigens characteristic of mesenchymal progenitor cells and were negative for hematopoietic differentiation antigens. Type II collagen and aggrecan mRNAs were expressed from day 14 in cells stimulated with BMP-2 or BMP-6. Type II collagen was demonstrated by Western blotting in both groups, and the greatest expression was observed 21 days after the cells were stimulated with BMP-2 cultured in micromass. BMP-2 in micromass culture was more efficient to induce the chondrogenesis.

Hepatic transplantation of mesenchymal stem cells in rodent animal models

The hepatocyte is the smallest functional entity of the liver and executes the majority of this organ's -metabolic functions. Hence, hepatocyte transplantation has become a versatile alternative to whole organ liver transplantation. This novel treatment option is based on the assumption that transplanted -hepatocytes integrate into the host liver, proliferate at the site of tissue damage, take over the long-term hepatic -synthetic capacity, and thus substitute for the diseased host tissue. However, clinical success is still waiting for a breakthrough, likely because of two major reasons including (1) the scarcity of cadaveric donor livers and (2) the largely poor quality of cells isolated from marginal quality donor organs. Therefore, alternative cell sources have to be established to further prompt the clinical success of hepatocyte transplantation. Due to their multiple differentiation potential and nearly unlimited availability, stem cells are an attractive -alternate resource. Because of both clinical and ethical objections, adult stem cells are often preferred over embryonic stem cells as a starting material. Recent studies have demonstrated the ability of mesenchymal stem cells derived from various tissues to differentiate into hepatocyte-like cells in vitro as well as showing specific hepatocyte functions in vivo after transplantation into the livers of mice or rats.

Stem cell therapy for liver disease: parameters governing the success of using bone marrow mesenchymal stem cells

BACKGROUND & AIMS

Liver transplantation is the primary treatment for various end-stage hepatic diseases but is hindered by the lack of donor organs and by complications associated with rejection and immunosuppression. There is increasing evidence to suggest the bone marrow is a transplantable source of hepatic progenitors. We previously reported that multipotent bone marrow-derived mesenchymal stem cells differentiate into functional hepatocyte-like cells with almost 100% induction frequency under defined conditions, suggesting the potential for clinical applications. The aim of this study was to critically analyze the various parameters governing the success of bone marrow-derived mesenchymal stem cell-based therapy for treatment of liver diseases.

METHODS

Lethal fulminant hepatic failure in nonobese diabetic severe combined immunodeficient mice was induced by carbon tetrachloride gavage. Mesenchymal stem cell-derived hepatocytes and mesenchymal stem cells were then intrasplenically or intravenously transplanted at different doses.

RESULTS

Both mesenchymal stem cell-derived hepatocytes and mesenchymal stem cells, transplanted by either intrasplenic or intravenous route, engrafted recipient liver, differentiated into functional hepatocytes, and rescued liver failure. Intravenous transplantation was more effective in rescuing liver failure than intrasplenic transplantation. Moreover, mesenchymal stem cells were more resistant to reactive oxygen species in vitro, reduced oxidative stress in recipient mice, and accelerated repopulation of hepatocytes after liver damage, suggesting a possible role for paracrine effects.

CONCLUSIONS

Bone marrow-derived mesenchymal stem cells can effectively rescue experimental liver failure and contribute to liver regeneration and offer a potentially alternative therapy to organ transplantation for treatment of liver diseases.

Mesenchymal stem cells cooperate with bone marrow cells in therapy of diabetes

Several recent studies have suggested that the adult bone marrow harbors cells that can influence beta-cell regeneration in diabetic animals. Other reports, however, have contradicted these findings. To address this issue, we used an animal model of type 1 diabetes in which the disease was induced with streptozotocin in mice. Freshly prepared sex-mismatched bone marrow cells (BMCs) and syngeneic or allogeneic mesenchymal stem cells (MSCs) were concomitantly administrated into sublethally irradiated diabetic mice. Blood glucose and serum insulin concentrations rapidly returned to normal levels, accompanied by efficient tissue regeneration after a single injection of a mixture of 10(6) BMCs per 10(5) MSCs. Neither BMC nor MSC transplantation was effective alone. Successful treatment of diabetic animals was not due to the reconstitution of the damaged islet cells from the transplant, since no donor-derived beta-cells were found in the recovered animals, indicating a graft-initiated endogenous repair process. Moreover, MSC injection caused the disappearance of beta-cell-specific T lymphocytes from diabetic pancreas. Therefore, we suggest that two aspects of this successful treatment regimen operate in parallel and synergistically in our model. First, BMCs and MSCs induce the regeneration of recipient-derived pancreatic insulin-secreting cells. Second, MSCs inhibit T-cell-mediated immune responses against newly formed beta-cells, which, in turn, are able to survive in this altered immunological milieu. Thus, the application of this therapy in human patients suffering from diabetes and/or other tissue destructive autoimmune diseases may be feasible.

Environmental monitoring in stem cell banks

The processing of stem cell lines for application in human therapy requires a physical environment in which air quality (i.e., the number of airborne particles) is controlled to minimize risk of contamination. The processing facility should be constructed and operated to minimise the introduction, generation and retention of particles and microorganisms. A formal program of environmental monitoring should be maintained in each stem cell bank to specify and assess key factors and their influence on the microbiological quality of the process and product. This program should assure the manipulation of cells involved in the derivation of stem cell lines and their culture under established limits for airborne particles and for microbial contamination of the air and surfaces. Environmental monitoring should also address the regulatory requirements in the countries in which the cells will be used. The monitoring programme will depend on local conditions in each processing centre or cell bank. Each centre will need to evaluate its specific needs and establish appropriate monitoring procedures which should not become intrusive to the extent that they might compromise the quality of the cell banks or products.