Insulin-like growth factor 1 (IGF-I) improves hepatic differentiation of human bone marrow-derived mesenchymal stem cells. Cell Biol Int. 2011;35:1169-1176. [PMID: 21910691 DOI: 10.1042/CBI20110016]

Recent advances in pre-conditioned mesenchymal stem/stromal cell (MSCs) therapy in organ failure; a comprehensive review of preclinical studies

Mesenchymal stem/stromal cells (MSCs)-based therapy brings the reassuring capability to regenerative medicine through their self-renewal and multilineage potency. Also, they secret a diversity of mediators, which are complicated in moderation of deregulated immune responses, and yielding angiogenesis in vivo. Nonetheless, MSCs may lose biological performance after procurement and prolonged expansion in vitro. Also, following transplantation and migration to target tissue, they encounter a harsh milieu accompanied by death signals because of the lack of proper tensegrity structure between the cells and matrix. Accordingly, pre-conditioning of MSCs is strongly suggested to upgrade their performances in vivo, leading to more favored transplantation efficacy in regenerative medicine. Indeed, MSCs ex vivo pre-conditioning by hypoxia, inflammatory stimulus, or other factors/conditions may stimulate their survival, proliferation, migration, exosome secretion, and pro-angiogenic and anti-inflammatory characteristics in vivo. In this review, we deliver an overview of the pre-conditioning methods that are considered a strategy for improving the therapeutic efficacy of MSCs in organ failures, in particular, renal, heart, lung, and liver.

Management of Persistent Pulmonary Hypertension After Correction of Congenital Heart Defect with Autologous Marrow-Derived Mononuclear Stem Cell Injection into the Pulmonary Artery: A Pilot Study

Pulmonary arterial hypertension (PAH) related to left-to-right shunt can progress to Eisenmenger syndrome, a serious and fatal disease that is not yet curable. This pilot study considered stem cell injection as a new treatment modality in persistent pulmonary hypertension after the correction of a congenital heart defect. Three patients with persistent pulmonary hypertension after ventricular septal defect repair were included in this pilot study for a clinical trial. Mononuclear stem cells derived from patients' bone marrow specimens were injected into the right and left pulmonary arteries via cardiac catheterization. The patients were followed over a 6-month period, with six-minute walk test, echocardiography and repeated angiography performed in the sixth month after treatment. The results of the study showed improvement of 40 m, 280 m and 100 m in 6-minute walk distance in patients 1 to 3, respectively. The peak PR gradient decreased 2, 5 and 9 mmHg by echocardiography, and mean PA pressure decreased 21, 22 and 9 mmHg by catheterization in patients 1 to 3, respectively. Pulmonary artery resistance decreased 4, 4.5 and 1.3 Wood units after 6 months of stem cell therapy in the three patients. No short-term complications were detected in this pilot trial, and all patients tolerated the procedure without any complications. Intrapulmonary artery injection of stem cells may have a role in the treatment of persistent PAH secondary to congenital heart disease. This procedure is feasible, with no significant complications, and this study can be considered as a platform for larger studies.

Insulin/IGF signaling and discoidin domain receptors: An emerging functional connection

The insulin/insulin-like growth factor system (IIGFs) plays a fundamental role in the regulation of prenatal and postnatal growth, metabolism and homeostasis. As a consequence, dysregulation of this axis is associated with growth disturbance, type 2 diabetes, chronic inflammation and tumor progression. A functional crosstalk between IIGFs and discoidin domain receptors (DDRs) has been recently discovered. DDRs are non-integrin collagen receptors that canonically undergo slow and long-lasting autophosphorylation after binding to fibrillar collagen. While both DDR1 and DDR2 functionally interact with IIGFs, the crosstalk with DDR1 is so far better characterized. Notably, the IIGFs-DDR1 crosstalk presents a feed-forward mechanism, which does not require collagen binding, thus identifying novel non-canonical action of DDR1. Further studies are needed to fully explore the role of this IIGFs-DDRs functional loop as potential target in the treatment of inflammatory and neoplastic disorders.

Insulin-like growth factor-I promotes hepatic differentiation of human adipose tissue-derived stem cells

There are numerous studies which provide support for the use of human adipose tissue-derived stem cells (hASCs) to generate hepatocyte-like cells. However, the produced cells exhibit only a certain level of differentiation, mainly due to inefficient induction conditions. Therefore, based on the important role of insulin-like growth factor (IGF-I) in hepatic function and development, in the current study we evaluated the differentiation efficacy of the mentioned factor to induce hASCs into functional hepatocyte-like cells. To investigate this, using a two-step protocol, hASCs were treated with a combination of HGF, Dex, and OSM in the presence or absence of IGF-I up to 21 days. Hepatic differentiation was evaluated by analyzing specific hepatocyte markers at different time points of differentiation induction. Increased expression of hepatocyte-specific genes including ALB, AFP, CK18, and HNF4a, downregulation of bile duct cells marker (CK19), the higher number of ALB positive cells, increased urea production together with higher glycogen deposit was observed upon the treatment of hASCs with the induction medium containing IGF-I compared to the other treatment. In conclusion, our findings suggest IGF-I as a potent inducer of hepatic differentiation of hASCs and its potential to generate more functional hepatocyte-like cells.

IGF-1 and somatocrinin trigger islet differentiation in human amniotic membrane derived mesenchymal stem cells

AIM

To induce differentiation of human amniotic membrane derived mesenchymal stem cells (hAMMSCs) into insulin producing cells (IPCs) by treating with somatocrinin or growth hormone releasing hormone (GHRH) and Insulin-like growth factor-1 (IGF-1).

MAIN METHOD

In this investigation, we cultivated and characterized hAMMSCs and then treated with IGF-1 and somatocrinin to find out whether this combination gives better yield of insulin producing cells. We showed that hAMMSCs can give rise to IPCs on exposure to serum-free defined media containing specific growth factors and differentiating agents in presence of IGF-1 and somatocrinin.

KEY FINDING

A combination of IGF-1 and somatocrinin lead to differentiation of large number of IPCs from hAMMSCs. These IPCs were found to be positive for dithizone indicating their insulin secretory mechanism. Moreover these cells were also found to be positive for C-peptide. IPCs released insulin in response to glucose challenge. Gene expression analysis exhibited significant up-regulation of pancreatic transcription factor GLUT2 and Insulin.

SIGNIFICANCE

Our data thus demonstrates for the first time that somatocrinin and IGF-1 synergistically enhance the differentiation of hAMMSCs into IPCs.

Establishing normal metabolism and differentiation in hepatocellular carcinoma cells by culturing in adult human serum

Tissue culture medium routinely contains fetal bovine serum (FBS). Here we show that culturing human hepatoma cells in their native, adult serum (human serum, HS) results in the restoration of key morphological and metabolic features of normal liver cells. When moved to HS, these cells show differential transcription of 22–32% of the genes, stop proliferating, and assume a hepatocyte-like morphology. Metabolic analysis shows that the Warburg-like metabolic profile, typical for FBS-cultured cells, is replaced by a diverse metabolic profile consistent with in vivo hepatocytes, including the formation of large lipid and glycogen stores, increased glycogenesis, increased beta-oxidation and ketogenesis, and decreased glycolysis. Finally, organ-specific functions are restored, including xenobiotics degradation and secretion of bile, VLDL and albumin. Thus, organ-specific functions are not necessarily lost in cell cultures, but might be merely suppressed in FBS. The effect of serum is often overseen in cell culture and we provide a detailed study in the changes that occur and provide insight in some of the serum components that may play a role in the establishment of the differentiated phenotype.

RNA-sequencing-based comparative analysis of human hepatic progenitor cells and their niche from alcoholic steatohepatitis livers

Hepatic progenitor cells (HPCs) are small cells with a relative large oval nucleus and a scanty cytoplasm situated in the canals of Hering that express markers of (immature) hepatocytes and cholangiocytes. HPCs are present in large numbers in alcoholic steatohepatitis (ASH), one of the leading causes of chronic liver disease. To date, the mechanisms responsible for proliferation and differentiation of human HPCs are still poorly understood and the role of HPCs in ASH development is unknown. In this study, we aimed to characterise human HPCs and their interactions with other cells through comparison, on both protein and RNA level, of HPC-enriched cell populations from adult human liver tissue using different isolation methods. Fresh human liver tissue was collected from ASH explant livers and HPC-enriched cell populations were obtained via four different isolation methods: side population (SP), epithelial cell adhesion molecule (EpCAM) and trophoblast antigen 2 (TROP-2) membrane marker isolation and laser capture microdissection. Gene expression profiles of fluorescent-activated cell-sorted HPCs, whole liver extracts and laser microdissected HPC niches were determined by RNA-sequencing. Immunohistochemical evaluation of the isolated populations indicated the enrichment of HPCs in the SP, EpCAM⁺ and TROP-2⁺ cell populations. Pathway analysis of the transcription profiles of human HPCs showed an enrichment and activation of known HPC pathways like Wnt/β-catenin, TWEAK and HGF. Integration of the HPC niche profile suggests autocrine signalling by HPCs (TNFα, PDGFB and VEGFA) as well as paracrine signalling from the surrounding niche cells including MIF and IGF-1. In addition, we identified IL-17 A signalling as a potentially novel pathway in HPC biology. In conclusion, we provide the first RNA-seq-based, comparative transcriptome analysis of isolated human HPCs from ASH patients and revealed active signalling between HPCs and their surrounding niche cells in ASH livers and suggest that HPCs can actively contribute to liver inflammation.

Regulation of Osteogenic Differentiation of Placental-Derived Mesenchymal Stem Cells by Insulin-Like Growth Factors and Low Oxygen Tension

Placental mesenchymal stem cells (PMSCs) are multipotent cells that can differentiate in vitro to multiple lineages, including bone. Insulin-like growth factors (IGFs, IGF-1 and IGF-2) participate in maintaining growth, survival, and differentiation of many stem cells, including osteoprogenitors. Low oxygen tension (PO₂) can maintain stem cell multipotency and impede osteogenic differentiation. In this study, we investigated whether PMSC osteogenic differentiation is influenced by low PO₂ and by IGFs. Our results indicated that low PO₂ decreased osteogenic markers RUNX2 and OPN; however, re-exposure to higher oxygen tension (room air) restored differentiation. IGFs, especially IGF-1, triggered an earlier expression of RUNX2 and enhanced OPN and mineralization. RUNX2 was phosphorylated in room air and augmented by IGFs. IGF-1 receptor (IGF-1R) was increased in low PO₂ and reduced by IGFs, while insulin receptor (IR) was increased in differentiating PMSCs and enhanced by IGF-1. Low PO₂ and IGFs maintained higher IR-A which was switched to IR-B in room air. PI3K/AKT was required for osteogenic differentiation, while MEK/ERK was required to repress an RUNX2 and OPN increase in low PO₂. Therefore, IGFs, specifically IGF-1, trigger the earlier onset of osteogenic differentiation in room air, whereas, reversibly, low PO₂ impedes complete differentiation by maintaining higher multipotency and lower differentiation markers.

The Roles of Insulin-Like Growth Factors in Mesenchymal Stem Cell Niche

Many tissues contain adult mesenchymal stem cells (MSCs), which may be used in tissue regeneration therapies. However, the MSC availability in most tissues is limited which demands expansion in vitro following isolation. Like many developing cells, the state of MSCs is affected by the surrounding microenvironment, and mimicking this natural microenvironment that supports multipotent or differentiated state in vivo is essential to understand for the successful use of MSC in regenerative therapies. Many researchers are, therefore, optimizing cell culture conditions in vitro by altering growth factors, extracellular matrices, chemicals, oxygen tension, and surrounding pH to enhance stem cells self-renewal or differentiation. Insulin-like growth factors (IGFs) system has been demonstrated to play an important role in stem cell biology to either promote proliferation and self-renewal or enhance differentiation onset and outcome, depending on the cell culture conditions. In this review, we will describe the importance of IGFs, IGF-1 and IGF-2, in development and in the MSC niche and how they affect the pluripotency or differentiation towards multiple lineages of the three germ layers.

The use of human umbilical cord blood serum is beneficial for the continuous production of hepatitis C virus

In this study we investigated if human umbilical cord blood serum (CBS) is a suitable replacement for foetal bovine serum (FBS) in cultures of human hepatoma cell line Huh7.5, particularly regarding its capacity to maintain high growth rates, differentiation status and its ability to support robust hepatitis C virus (HCV) infection. Generally, CBS-cultured Huh7.5 cells remained comparable to FBS-cultured cells, and proliferated equally well. Albumin secretion, a hepatocyte differentiation marker, had increased 8x in CBS; however, most other hepatocyte markers we tested had not changed. Surprisingly, CBS-cultured cells were able to sustain very high levels of HCV production, and HCV infection in CBS-cultured cells did not induce cell lysis, which is typically seen in HCV-infected cells cultured in FBS. We discuss some of the differences between CBS, adult human serum and FBS that may explain the differences observed.

Evaluation of bone marrow derived mesenchymal stem cells for full-thickness wound healing in comparison to tissue engineered chitosan scaffold in rabbit

BACKGROUND

Chronic wounds present a major challenge in modern medicine. Even under optimal conditions, the healing process may lead to scarring and fibrosis. The ability of mesenchymal stem cells (MSCs) to differentiate into other cell types makes these cells an attractive therapeutic tool for cell transplantation. Both tissue-engineered construct and MSC therapy are among the current wound healing procedures and potential care. Chitosan has been widely applied in tissue engineering because of its biocompatibility and biodegradability.

AIM

The aim of the current work was to compare the efficiency of MSCs and chitosan dressing, alone or in combination treatment on wound healing.

METHODS

This study was conducted on 15 rabbits, which were randomly divided in 3 groups based on the type of treatment with MSCs, chitosan dressing and combination of both. A full-thickness skin defect was excised from the right and left side of the back of each animals. Defects on right sides were filled with treatments and left side defects were left as control. Evaluation of the therapeutic effectiveness was performed through a variety of clinical and microscopical evaluations and measurements of the process of wound healing on days 7, 14, 21, and 28. Histological evaluation of wound healing was classified by different scoring systems.

RESULTS

The data indicated that wounds treated with bone marrow derived MSC had enhanced cellularity and better epidermal regeneration. During the early stages of wound healing, the closure rate of bone marrow derived MSC-treated wounds were significantly higher than other treatments (P<0.05). Although the MSCs in the wound edges enhance the healing of the full-thickness wound, the healing process of chitosan treatment was slower than the control group.

CONCLUSION

This study revealed advanced granulation tissue formation and epithelialization in wounds treated with MSCs, and may suggests this treatment as an effective applicant in wound healing process. Chitosan scaffold dressings, whether alone or in combination with MSCs, have worsened the wound healing as compared to the control group.

Tissue engineering strategy using mesenchymal stem cell-based chitosan scafolds in growth plate surgery: a preliminary study in rabbits

BACKGROUND

Growth plate injury in children could produce limb length discrepancy and angular deformity. Removal of damaged physis or bony bar and insertion of spacers produced variable results and for large defects in young children, the treatment is challenging. In this study, we used tissue-engineered mesenchymal stem cells (MSC-based chitosan scaffold) for restoration of the damaged physis. The usage of chitosan as a spacer was also investigated.

MATERIALS AND METHODS

An experimental model of growth arrest was created by removing lateral 50% of distal femoral physis of fourteen 4-week-olds albino rabbits. The left side growth plate defects were filled with MSC-based chitosan scaffold in 10 and scaffold alone in 4 rabbits. For all the rabbits, right-side defects were left alone as the control limb. After 3 months, femoral bones were harvested and gross inspection and radiology for measurement of angulations were done; histological study for evaluation of regeneration of physis was also done.

RESULTS

The hemiphyseal resection procedures were successful and all of the operated limbs showed angular deformities. There was a trend toward less angular deformity in cases in which more concentration of MSCs with chitosan scaffold was used. In cases of transfer of MSCs with concentration of less than 1.5 millions, mixed results were observed and angular deformities were not reduced. Transfer of chitosan alone yielded poor results.

CONCLUSION

In this study, we have developed an in vitro construction of a transplantable tissue-engineered disk, using natural chitosan scaffold and MSCs. We investigated the efficacy of these disks for repairing the defect of growth plate cartilage at distal femoral physis. Our results showed that the beneficial effect of these cells on scaffold appeared in more concentration of cells.

LEVEL OF EVIDENCE

Level III. Low power comparative study.

The multiple functional roles of mesenchymal stem cells in participating in treating liver diseases

Mesenchymal stem cells (MSCs) are a group of stem cells derived from the mesodermal mesenchyme. MSCs can be obtained from a variety of tissues, including bone marrow, umbilical cord tissue, umbilical cord blood, peripheral blood and adipose tissue. Under certain conditions, MSCs can differentiate into many cell types both in vitro and in vivo, including hepatocytes. To date, four main strategies have been developed to induce the transdifferentiation of MSCs into hepatocytes: addition of chemical compounds and cytokines, genetic modification, adjustment of the micro-environment and alteration of the physical parameters used for culturing MSCs. Although the phenomenon of transdifferentiation of MSCs into hepatocytes has been described, the detailed mechanism is far from clear. Generally, the mechanism is a cascade reaction whereby stimulating factors activate cellular signalling pathways, which in turn promote the production of transcription factors, leading to hepatic gene expression. Because MSCs can give rise to hepatocytes, they are promising to be used as a new treatment for liver dysfunction or as a bridge to liver transplantation. Numerous studies have confirmed the therapeutic effects of MSCs on hepatic fibrosis, cirrhosis and other liver diseases, which may be related to the differentiation of MSCs into functional hepatocytes. In addition to transdifferentiation into hepatocytes, when MSCs are used to treat liver disease, they may also inhibit hepatocellular apoptosis and secrete various bioactive molecules to promote liver regeneration. In this review, the capacity and molecular mechanism of MSC transdifferentiation, and the therapeutic effects of MSCs on liver diseases are thoroughly discussed.

Involvement of TNF-α in differential gene expression pattern of CXCR4 on human marrow-derived mesenchymal stem cells

Cell therapy and tissue repair are used in a variety of diseases including tissue and organ transplantation, autoimmune diseases and cancers. Now mesenchymal stem cells (MSCs) are an attractive and promising source for cell-based therapy according to their individual characteristics. Soluble factors which are able to induce MSCs migration have a vital role in cell engraftment and tissue regeneration. Tumor necrosis factor α (TNF-α) is a major cytokine present in damaged tissues. We have investigated the pattern of gene expression of chemokine receptor CXCR4 in nine groups of human bone marrow-derived MSCs stimulated with TNF-α in different dose and time manner. Comparison of TNF-α treated with untreated MSCs revealed the highest expression level of CXCR4 after treatment with 1, and 10 ng/ml of TNF-α in 24 h, and the production of CXCR4 mRNA was regulated up to 216 and 512 fold, respectively. Our results demonstrated the differential gene expression pattern of chemokine receptor CXCR4 in human marrow-derived MSCs stimulated with inflammatory cytokine TNF-α. These findings suggest that in vitro control of both dose and time factors may be important in stem cell migration capacity, and perhaps in future-stem cell transplantation therapies.

Role of stromal-epithelial interaction in the formation and development of cancer cells

Identification of gene expression mechanisms began with works on embryonic induction. The same mechanism of cell-cell interactions also contributes to the process of oncogenesis. Damage to epithelial cells' genetic apparatus turns them into precancerous stem cells that are not yet capable of tumor growth. They can be transformed into cancer stem cells and undergo further progression as a result of epigenetic effects of apocrine secretion by surrounding activated stromal cells (mostly myofibroblasts). These factors may activate the damaged genetic information. On the contrary, the level of malignancy can be decreased by adding culture medium from non-activated stromal cells. One must not exclude the possibility that in a number of cases genetically altered bone marrow may migrate to damaged or inflamed tissues and become there a source of stromal cells, as well as of parenchymal stem cells in a damaged organ, where they may give rise to changed epithelial (precancerous) stem cells or to activated stromal cells, thus leading to malignant tumor growth. Cancer treatment should also affect activated stromal cells. It may prevent emergence and progression of cancerous stem cells.

The key role of insulin-like growth factor I in limbal stem cell differentiation and the corneal wound-healing process

Limbal stem cells (LSC), which reside in the basal layer of the limbus, are thought to be responsible for corneal epithelial healing after injury. When the cornea is damaged, LSC start to proliferate, differentiate, and migrate to the site of injury. To characterize the signaling molecules ensuring communication between the cornea and LSC, we established a mouse model of mechanical corneal damage. The central cornea or limbal tissue was excised at different time intervals after injury, and the expression of genes in the explants was determined. It was observed that a number of genes for growth and differentiation factors were significantly upregulated in the cornea rapidly after injury. The ability of these factors to regulate the differentiation and proliferation of limbal cells was tested. It was found that the insulin-like growth factor-I (IGF-I), which is rapidly overexpressed after injury, enhances the expression of IGF receptor in limbal cells and induces the differentiation of LSC into cells expressing the corneal cell marker, cytokeratin K12, without any effect on limbal cell proliferation. In contrast, the epidermal growth factor (EGF) and fibroblast growth factor-β (FGF-β), which are also produced by the damaged corneal epithelium, supported limbal cell proliferation without any effect on their differentiation. Other factors did not affect limbal cell differentiation or proliferation. Thus, IGF-I was identified as the main factor stimulating the expression of IGF receptors in limbal cells and inducing the differentiation of LSC into cells expressing corneal epithelial cell markers. The proliferation of these cells was supported by EGF and FGF.

Progress in research of differentiation of mesenchymal stem cells into functional hepatocytes

Mesenchymal stem cells (MSCs) are a group of stem cells deriving from mesodermal mesenchyme. They can be recovered from a variety of tissues, including bone marrow, umbilical cord tissue, umbilical cord blood, peripheral blood and adipose tissue. Under given conditions, MSCs can differentiate into bone, fat, nerve cells, hepatocytes and many other cells, and thus can be used as a new treatment to substitute for organ transplantation. In recent years, the incidence of end-stage liver disease has been increasing and it has become one of the major diseases affecting human health. Donor scarcity and immunological rejection limit the clinical application of liver transplantation. Numerous studies have confirmed the therapeutic effects of MSCs on hepatic fibrosis, cirrhosis and other liver diseases, which may be related to the differentiation of MSCs into functional hepatocytes. This paper reviews the capacity, regulation and molecular mechanism of MSC differentiation and discusses the therapeutic effects of different sources of stem cells for liver fibrosis.