Transfer and expression of rhSCF gene in human hematopoietic stem/progenitor cells

Stem cell factor (SCF) is a novel growth factor thatinfluences the growth and development of hematopoieticcells, germ cells and melanocytes. To explore the     

Autologous hematopoietic stem cells for refractory Crohn’s disease

Introduction: Autologous hematopoietic stem cells are gaining ground as an effective and safe treatment for treating severe refractory Crohn’s disease (CD). Autologous hematopoietic stem cell therapy (AHSCT) induces resetting of the immune system by de novo regeneration of T-cell repertoire and repopulation of epithelial cells by bone-marrow derived cells to help patients achieve clinical and endoscopic remission.

Areas covered: Herein, the authors discuss the use of AHSCT in treating patients with CD. Improvements in disease activity have been seen in patients with severe autoimmune disease and patients with severe CD who underwent AHSCT for a concomitant malignant hematological disease. Clinical and endoscopic remission has been achieved in patients treated with AHSCT for CD. The only randomized trial published to date, the ASTIC Trial, did not support further use of AHSCT to treat CD. Yet, critics of this trial have deemed AHSCT as a promising treatment for severe refractory CD.

Expert opinion: Even with the promising evidence presented for HSCT for refractory CD, protocols need to be refined through the collaboration of GI and hemato-oncology professionals. The goal is to incorporate safe AHSCT and restore tolerance by delivering an effective immune ‘cease fire’ as a treatment option for severe refractory CD.     

Human muscle–derived stem/progenitor cells promote functional murine peripheral nerve regeneration

Peripheral nerve injuries and neuropathies lead to profound functional deficits. Here, we have demonstrated that muscle-derived stem/progenitor cells (MDSPCs) isolated from adult human skeletal muscle (hMDSPCs) can adopt neuronal and glial phenotypes in vitro and ameliorate a critical-sized sciatic nerve injury and its associated defects in a murine model. Transplanted hMDSPCs surrounded the axonal growth cone, while hMDSPCs infiltrating the regenerating nerve differentiated into myelinating Schwann cells. Engraftment of hMDSPCs into the area of the damaged nerve promoted axonal regeneration, which led to functional recovery as measured by sustained gait improvement. Furthermore, no adverse effects were observed in these animals up to 18 months after transplantation. Following hMDSPC therapy, gastrocnemius muscles from mice exhibited substantially less muscle atrophy, an increase in muscle mass after denervation, and reorganization of motor endplates at the postsynaptic sites compared with those from PBS-treated mice. Evaluation of nerve defects in animals transplanted with vehicle-only or myoblast-like cells did not reveal histological or functional recovery. These data demonstrate the efficacy of hMDSPC-based therapy for peripheral nerve injury and suggest that hMDSPC transplantation has potential to be translated for use in human neuropathies.     

Human ovarian carcinoma–associated mesenchymal stem cells regulate cancer stem cells and tumorigenesis via altered BMP production

Accumulating evidence suggests that mesenchymal stem cells (MSCs) are recruited to the tumor microenvironment; however, controversy exists regarding their role in solid tumors. In this study, we identified and confirmed the presence of carcinoma-associated MSCs (CA-MSCs) in the majority of human ovarian tumor samples that we analyzed. These CA-MSCs had a normal morphologic appearance, a normal karyotype, and were nontumorigenic. CA-MSCs were multipotent with capacity for differentiating into adipose, cartilage, and bone. When combined with tumor cells in vivo, CA-MSCs promoted tumor growth more effectively than did control MSCs. In vitro and in vivo studies suggested that CA-MSCs promoted tumor growth by increasing the number of cancer stem cells. Although CA-MSCs expressed traditional MSCs markers, they had an expression profile distinct from that of MSCs from healthy individuals, including increased expression of BMP2, BMP4, and BMP6. Importantly, BMP2 treatment in vitro mimicked the effects of CA-MSCs on cancer stem cells, while inhibiting BMP signaling in vitro and in vivo partly abrogated MSC-promoted tumor growth. Taken together, our data suggest that MSCs in the ovarian tumor microenvironment have an expression profile that promotes tumorigenesis and that BMP inhibition may be an effective therapeutic approach for ovarian cancer.     

Kindlin-3–mediated integrin adhesion is dispensable for quiescent but essential for activated hematopoietic stem cells

Hematopoietic stem cells (HSCs) generate highly dividing hematopoietic progenitor cells (HPCs), which produce all blood cell lineages. HSCs are usually quiescent, retained by integrins in specific niches, and become activated when the pools of HPCs decrease. We report that Kindlin-3–mediated integrin activation controls homing of HSCs to the bone marrow (BM) and the retention of activated HSCs and HPCs but not of quiescent HSCs in their BM niches. Consequently, Kindlin-3–deficient HSCs enter quiescence and remain in the BM when cotransplanted with wild-type hematopoietic stem and progenitor cells (HSPCs), whereas they are hyperactivated and lost in the circulation when wild-type HSPCs are absent, leading to their exhaustion and reduced survival of recipients. The accumulation of HSPCs in the circulation of leukocyte adhesion deficiency type III patients, who lack Kindlin-3, underlines the conserved functions of Kindlin-3 in man and the importance of our findings for human disease.The entire hematopoietic system is derived from, and maintained by, a small number of hematopoietic stem cells (HSCs) that reside in the BM. HSCs are characterized by their low cycling rate and their ability to self-renew throughout the life span of an organism. After hematopoietic injury (e.g., bleeding), quiescent HSCs become activated, replenish the pool of hematopoietic effector cells, and return to the quiescent state (Trumpp et al., 2010). To maintain HSCs throughout the life of an animal, the oscillation of HSCs between quiescence, activation, self-renewal, and differentiation is precisely regulated in a specific microenvironment referred to as the stem cell niche (Morrison and Scadden, 2014). The oscillation of HSCs is regulated through interactions with niche cells (Kiel and Morrison, 2008), extracellular matrix (ECM) proteins (van der Loo et al., 1998), the action of cytokines, chemokines, and growth factors that are released by niche cells (Rizo et al., 2006), and calcium gradients established by osteoclasts during bone remodeling (Adams et al., 2006). Thus, an impairment of the HSC–niche interplay can result in loss of quiescence, uncontrolled activation, and finally exhaustion of HSCs.The interactions of HSCs with niche cells and ECM are mediated by adhesion molecules such as integrins (Wilson and Trumpp, 2006). Integrins are expressed on all cells including tissue stem cells, where they mediate binding to ECM and counter receptors (Hynes, 2002). The composition of niche cells and ECM components is unique in each organ, and hence tissue stem cells express specific integrin profiles to interact with their niche microenvironment. The integrin profile of HSCs includes multiple members of the β1 class (α2β1, α4β1, α5β1, α6β1, and α9β1), αLβ2 from the β2 class, and αvβ3 from the αv class (Grassinger et al., 2009). In vivo and in vitro studies using genetics or inhibitory antibodies demonstrated that integrins promote hematopoietic stem and progenitor cell (HSPC) homing to the BM (Potocnik et al., 2000) and their BM retention (Magnon and Frenette, 2008), proliferation, and differentiation (Arroyo et al., 1999).Integrin ligand binding and signaling require an activation step, which is induced after Talin and Kindlin bind to the cytoplasmic domains of integrin β subunits and is characterized by allosteric changes in the integrin ectodomain and transmembrane domains (Moser et al., 2009a; Shattil et al., 2010). Kindlins are evolutionarily conserved and consist of three members. Hematopoietic cells express Kindlin-3 (Ussar et al., 2006), whose deletion in mice abrogates integrin activation, resulting in hemorrhages, leukocyte adhesion defects, and osteopetrosis (Moser et al., 2008, 2009b; Schmidt et al., 2011). A human disease with similar abnormalities, called leukocyte adhesion deficiency type III (LAD-III), is also caused by null mutations of the KIND3 gene (also called FERMT3; Kuijpers et al., 2009; Malinin et al., 2009; Svensson et al., 2009).Because Kindlin-3 activates all integrins analyzed so far, it is perfectly suited to broadly abrogate integrin-dependent functions in HSCs. Here we report that proliferating hematopoietic progenitor cells (HPCs) require Kindlin-3 for their maintenance in the BM, whereas Kindlin-3–mediated integrin adhesion is dispensable for HSCs that enter quiescence. In a situation of hematopoietic stress and/or high demand for HPCs, quiescent HSCs are activated, refill the pools of HPCs, become dependent on Kindlin-3, and eventually are exhausted.     

Recombinant IL-7/HGFβ efficiently induces transplantable murine hematopoietic stem cells

Difficulty obtaining sufficient hematopoietic stem cells (HSCs) directly from the donor has limited the clinical use of HSC transplantation. Numerous attempts to stimulate the ex vivo growth of purified HSCs with cytokines and growth factors generally have induced only modest increases in HSC numbers while decreasing their in vivo reconstituting ability. We previously developed a recombinant single-chain form of a naturally occurring murine hybrid cytokine of IL-7 and the β chain of hepatocyte growth factor (rIL-7/HGFβ) that stimulates the in vitro proliferation and/or differentiation of common lymphoid progenitors, pre-pro-B cells, and hematopoietic progenitor cells (day 12 spleen colony-forming units) in cultures of mouse BM. Here we used the rIL-7/HGFβ in culture to induce large numbers of HSCs from multiple cell sources, including unseparated BM cells, purified HSCs, CD45^– BM cells, and embryonic stem cells. In each instance, most of the HSCs were in the G₀ phase of the cell cycle and exhibited reduced oxidative stress, decreased apoptosis, and increased CXCR4 expression. Furthermore, when injected i.v., these HSCs migrated to BM, self-replicated, provided radioprotection, and established long-term hematopoietic reconstitution. These properties were amplified by injection of rIL-7/HGFβ directly into the BM cavity but not by treatment with rIL-7, rHGF, and/or rHGFβ.     

Protein tyrosine phosphatase–σ regulates hematopoietic stem cell–repopulating capacity

Hematopoietic stem cell (HSC) function is regulated by activation of receptor tyrosine kinases (RTKs). Receptor protein tyrosine phosphatases (PTPs) counterbalance RTK signaling; however, the functions of receptor PTPs in HSCs remain incompletely understood. We found that a receptor PTP, PTPσ, was substantially overexpressed in mouse and human HSCs compared with more mature hematopoietic cells. Competitive transplantation of bone marrow cells from PTPσ-deficient mice revealed that the loss of PTPσ substantially increased long-term HSC-repopulating capacity compared with BM cells from control mice. While HSCs from PTPσ-deficient mice had no apparent alterations in cell-cycle status, apoptosis, or homing capacity, these HSCs exhibited increased levels of activated RAC1, a RhoGTPase that regulates HSC engraftment capacity. shRNA-mediated silencing of PTPσ also increased activated RAC1 levels in wild-type HSCs. Functionally, PTPσ-deficient BM cells displayed increased cobblestone area–forming cell (CAFC) capacity and augmented transendothelial migration capacity, which was abrogated by RAC inhibition. Specific selection of human cord blood CD34⁺CD38^–CD45RA^–lin^– PTPσ^– cells substantially increased the repopulating capacity of human HSCs compared with CD34⁺CD38^–CD45RA^–lin^– cells and CD34⁺CD38^–CD45RA^–lin^–PTPσ⁺ cells. Our results demonstrate that PTPσ regulates HSC functional capacity via RAC1 inhibition and suggest that selecting for PTPσ-negative human HSCs may be an effective strategy for enriching human HSCs for transplantation.     

Mesodermal iPSC–derived progenitor cells functionally regenerate cardiac and skeletal muscle

Conditions such as muscular dystrophies (MDs) that affect both cardiac and skeletal muscles would benefit from therapeutic strategies that enable regeneration of both of these striated muscle types. Protocols have been developed to promote induced pluripotent stem cells (iPSCs) to differentiate toward cardiac or skeletal muscle; however, there are currently no strategies to simultaneously target both muscle types. Tissues exhibit specific epigenetic alterations; therefore, source-related lineage biases have the potential to improve iPSC-driven multilineage differentiation. Here, we determined that differential myogenic propensity influences the commitment of isogenic iPSCs and a specifically isolated pool of mesodermal iPSC-derived progenitors (MiPs) toward the striated muscle lineages. Differential myogenic propensity did not influence pluripotency, but did selectively enhance chimerism of MiP-derived tissue in both fetal and adult skeletal muscle. When injected into dystrophic mice, MiPs engrafted and repaired both skeletal and cardiac muscle, reducing functional defects. Similarly, engraftment into dystrophic mice of canine MiPs from dystrophic dogs that had undergone TALEN-mediated correction of the MD-associated mutation also resulted in functional striatal muscle regeneration. Moreover, human MiPs exhibited the same capacity for the dual differentiation observed in murine and canine MiPs. The findings of this study suggest that MiPs should be further explored for combined therapy of cardiac and skeletal muscles.     

PDGFRα and CD51 mark human Nestin+ sphere-forming mesenchymal stem cells capable of hematopoietic progenitor cell expansion

The intermediate filament protein Nestin labels populations of stem/progenitor cells, including self-renewing mesenchymal stem cells (MSCs), a major constituent of the hematopoietic stem cell (HSC) niche. However, the intracellular location of Nestin prevents its use for prospective live cell isolation. Hence it is important to find surface markers specific for Nestin⁺ cells. In this study, we show that the expression of PDGFRα and CD51 among CD45⁻ Ter119⁻ CD31⁻ mouse bone marrow (BM) stromal cells characterizes a large fraction of Nestin⁺ cells, containing most fibroblastic CFUs, mesenspheres, and self-renewal capacity after transplantation. The PDGFRα⁺ CD51⁺ subset of Nestin⁺ cells is also enriched in major HSC maintenance genes, supporting the notion that niche activity co-segregates with MSC activity. Furthermore, we show that PDGFRα⁺ CD51⁺ cells in the human fetal BM represent a small subset of CD146⁺ cells expressing Nestin and enriched for MSC and HSC niche activities. Importantly, cultured human PDGFRα⁺ CD51⁺ nonadherent mesenspheres can significantly expand multipotent hematopoietic progenitors able to engraft immunodeficient mice. These results thus indicate that the HSC niche is conserved between the murine and human species and suggest that highly purified nonadherent cultures of niche cells may represent a useful novel technology to culture human hematopoietic stem and progenitor cells.Hematopoietic stem cells (HSCs) continuously replenish all blood cell lineages throughout their lifetime. Incipient hematopoiesis is first detected extraembryonically in the yolk sac and later in the aorta–gonad–mesonephros region, from where it moves transiently to the placenta and liver before being stabilized in the fetal BM (Wang and Wagers, 2011). In the adult stage, HSCs reside in a highly complex and dynamic microenvironment of the BM commonly referred to as the HSC niche (Schofield, 1978). The interactions between the niche constituents and HSCs ensure hematopoietic homeostasis by regulating HSC self-renewal, differentiation, and migration and by integrating neural and hormonal signals from the periphery (Méndez-Ferrer et al., 2009, 2010; Mercier et al., 2012). However, HSC maintenance and expansion ex vivo still remains challenging mainly because of our limited knowledge on the in vivo HSC niche constituents and the factors that drive HSC self-renewal.Although the cellular constituents of the HSC niche and their role are still poorly understood, in the last decade, several putative cellular components of the murine HSC niche have been proposed, including osteoblastic, endothelial, adipocytic, and perivascular cells (Calvi et al., 2003; Zhang et al., 2003; Arai et al., 2004; Kiel et al., 2005; Sugiyama et al., 2006; Chan et al., 2009; Naveiras et al., 2009; Méndez-Ferrer et al., 2010; Ding et al., 2012). Multipotent BM mesenchymal stem cells (MSCs) have long been suggested to also provide regulatory signals to hematopoietic progenitors, as mixed cultures derived from the adherent fraction of the BM stroma promote the maintenance of HSCs in vitro (Dexter et al., 1977). Although numerous studies explored the ability of mesenchymal stromal cultures to support the ex vivo expansion of hematopoietic stem and progenitor cells (HSPCs), currently these systems are still insufficient to preserve primitive HSCs with long-term multilineage engraftment capacity (Chou et al., 2010; Broxmeyer, 2011). This limitation may in part be associated with the heterogeneous composition of mesenchymal stromal cell cultures. The prospective identification and functional characterization of purified naive populations of mouse and/or human BM stromal MSCs have been mired by the absence of specific cell surface markers allowing prospective isolation. Several MSC-associated antigens have been proposed (such as CD31⁻ CD34⁻ CD45⁻ CD105⁺ CD90⁺ CD73⁺) in cultured cells (Dominici et al., 2006). Nevertheless, these markers are not homogeneously expressed across cultures, varying with isolation protocols and passage and therefore not necessarily representative of MSCs in vivo (Bianco et al., 2013; Frenette et al., 2013). Very few MSC-associated antigens have been validated using rigorous transplantation assays (Sacchetti et al., 2007; Méndez-Ferrer et al., 2010). In the mouse BM, the expression of the intermediate filament protein Nestin characterizes a rare population of multipotent MSCs in close contact with the vasculature and HSCs. Nestin⁺ stromal cells contain all of the fibroblastic CFU (CFU-F) activity within the mouse BM and the exclusive capacity to form clonal nonadherent spheres in culture. The selective ablation of mouse Nestin⁺ cells (Méndez-Ferrer et al., 2010) or CXCL12-abundant reticular (CAR) cells (Omatsu et al., 2010) led to significant alterations in the BM HSC and progenitor maintenance. Serial transplantation analyses revealed that Nestin⁺ cells are able to self-renew and generate hematopoietic activity in heterotopic bone ossicle assays (Méndez-Ferrer et al., 2010). This potential was also associated with a CD45⁻ Tie2⁻ αV⁺ CD105⁺ CD90⁻ subset from the fetal mouse bone (Chan et al., 2009). In the adult mouse BM, PDGFRα⁺ Sca1⁺ CD45⁻ Ter119⁻ cells were also shown capable to give rise to osteoblasts, reticular cells, and adipocytes in vivo upon transplantation into irradiated mice (Morikawa et al., 2009). However, human BM MSCs are still retrospectively isolated based on plastic adherence (Friedenstein et al., 1970; Pittenger et al., 1999). Human CD45⁻ CD146⁺ self-renewing osteoprogenitors isolated from stromal cultures containing all the human BM CFU-F activity were shown capable of generating a heterotopic BM niche in an s.c. transplantation model (Sacchetti et al., 2007). However, a recent study showed that human CD45⁻ CD271⁺ CD146^−/low BM cells also possess these capacities (Tormin et al., 2011).Because Nestin is an intracellular protein, its identification in nontransgenic mice requires cell permeabilization, which precludes prospective isolation of live cells. In this study, we have evaluated putative cell surface MSC markers to identify a stromal population equivalent to Nestin⁺ cells in the mouse and human BM. Our results show that the combination of PDGFRα and CD51 identify a large subset of perivascular Nestin⁺ cells that is highly enriched in MSC and HSC niche activities in both species. Furthermore, we show that PDGFRα⁺ CD51⁺ stromal cells isolated from human BM can also form self-renewing clonal mesenspheres capable of transferring hematopoietic niche activity in vivo and support the ex vivo maintenance and expansion of human HSPCs in a dose-dependent manner.     

Pancreatic cancer stem cells – insights and perspectives

Background: Solid tumours are the most common cancers and represent a major therapeutic challenge. The cancer stem cell (CSC) hypothesis is an attractive model to explain the functional heterogeneity commonly observed in solid tumours. It proposes a hierarchical organization of tumours, in which a subpopulation of stem cell-like cells sustains tumour growth, metastasis and resistance to therapy. Objective: Here we review the most recent advances in the CSC field, with particular emphasis on pancreatic cancer as one of the deadliest human tumours, and highlight open questions and caveats to be addressed in future studies. Methods: This review focuses on the role of CSC in the promotion and metastasis of solid tumours and summarizes recent findings regarding the targeting of signalling pathways that are of particular importance for the maintenance and the elimination of CSC as the proposed root of the tumour. Results/conclusions: There is increasing evidence that solid tumours, including pancreatic cancer, are hierarchically organized and sustained by a distinct subpopulation of CSC. Direct evidence for the CSC hypothesis has emerged from mouse models only recently. While the clinical relevance of CSC remains a fundamental issue, current findings suggest that specific targeting of these cells is possible and therapeutically relevant.     

Brain tumour stem cells and neural stem cells: still explored by the same approach?

Brain tumour stem cells (BTSCs) are chiefly responsible for the in vivo long-term growth and recurrence of malignant gliomas and may be a potential treatment target. They resemble neural stem cells (NSCs), so their self-renewal and differentiation are currently investigated by the same methods used to study NSCs. There are, however, essential differences between these cell types: in many cases the marker expression pattern of BTSCs does not match the CD133(+)/NSE(-)/FAP(-) pattern of NSCs; BTSC tumourigenicity is independent of marker expression; and while attachment, serum-containing medium and withdrawal of mitogens (epidermal growth factor [EGF] and basic fibroblast growth factor [bFGF]) are essential to induce NSCs to differentiate, they do not affect BTSC tumourigenicity. Evidence implies that research on the renewal and differentiation of BTSCs should be orientated towards tumourigenicity and is essentially a pharmaceutical problem. Such an approach may contribute to the development of an accurate definition of BTSCs and to the search for selective differentiation-inducing drugs for BTSCs.     

Experimental studies on gene transfer into hematopoietic stem cells mediated by liposome and the influence of expansion on gene expression

Liposomes have several advantages over viral vectorsfor gene delivery both in vitro and in vivo. However,few data are available concerning gene transfer intohematopoietic stem cells. In order to explore theefficiency and the stability of expression of gene transferinto hematopoietic stem cells, we have transduced twomarker genes (Neo~R and Lac Z) co-transfer into humanbone marrow CD34~ hematopoietic stem cells mediated     

How chondrogenic are human umbilical cord matrix cells? A comparison to adipose‐derived stem cells

The umbilical cord matrix as well as liposuction material have been demonstrated to contain cells capable of differentiating towards the mesodermal lineage. High availability and low donor site morbidity appear promising for the use of human umbilical cord matrix cells (HUCMs) and adipose‐derived stem cells (ASCs) in cell‐based therapies. In the present study we focused on cartilage regeneration and compared HUCMs and ASCs regarding their potential to differentiate towards the chondrogenic lineage. Cells were isolated by explantation culture or enzymatic digestion, phenotypically characterized by flow cytometry and differentiated as 3D micromass pellets for up to 35 days. Under tested conditions, ASCs demonstrated significantly higher glycosaminoglycan synthesis compared to HUCMs. qRT–PCR data gave evidence that chondrogenic genes are expressed by both ASCs and HUCMs. However, higher expression levels of ASCs suggest that this cell type has higher potential for differentiation towards a cartilage‐like phenotype than HUCMs. In conclusion, both cell types, HUCMs and ASCs, are easily available, possess typical properties of mesenchymal stem cells and are thus promising for cell‐based therapies. However, in terms of cartilage regeneration, ASCs might be more suitable than HUCMs. Copyright © 2009 John Wiley & Sons, Ltd.     

Bone marrow as a source of hematopoietic stem cells for human gene therapy of β-thalassemia

β-Thalassemia is a severe inherited anemia caused by insufficient production of β-globin chains. Allogeneic hematopoietic stem cell (HSC) transplantation is currently the only cure, and is limited by donor availability and regimen-related toxicity and mortality. Gene therapy is a promising therapeutic tool for all thalassemic patients lacking a compatible donor and potentially provides transfusion independence in the absence of transplant-related complications, such as graft rejection and graft-versus-host disease. The issue of HSC procurement is critical in this setting because of the specific features of thalassemic syndromes, which include bone marrow (BM) expansion, ineffective erythropoiesis, and splenomegaly. Little is known about the efficiency of CD34(+) cell yield from steady-state BM harvests from thalassemic patients. We have collected data on safety and cell yield from 20 pediatric patients with β-thalassemia who underwent autologous BM harvest before allogeneic HSC transplantation, and from 49 age-matched sibling donors who also underwent BM harvest. The procedure was safe, as no significant adverse events occurred. In terms of cell yield, no difference was found between patients and normal donors in the number of CD34(+) cells and total nucleated cells harvested. Most importantly, no difference was found in the proportion of myeloid and erythroid progenitors, suggesting a similar repopulating capacity. On the basis of these results, we conclude that steady-state BM can be used as a safe and efficient source of HSC for gene therapy of β-thalassemia.     

Autologous mesenchymal stem cell–derived dopaminergic neurons function in parkinsonian macaques

A cell-based therapy for the replacement of dopaminergic neurons has been a long-term goal in Parkinson’s disease research. Here, we show that autologous engraftment of A9 dopaminergic neuron-like cells induced from mesenchymal stem cells (MSCs) leads to long-term survival of the cells and restoration of motor function in hemiparkinsonian macaques. Differentiated MSCs expressed markers of A9 dopaminergic neurons and released dopamine after depolarization in vitro. The differentiated autologous cells were engrafted in the affected portion of the striatum. Animals that received transplants showed modest and gradual improvements in motor behaviors. Positron emission tomography (PET) using [¹¹C]-CFT, a ligand for the dopamine transporter (DAT), revealed a dramatic increase in DAT expression, with a subsequent exponential decline over a period of 7 months. Kinetic analysis of the PET findings revealed that DAT expression remained above baseline levels for over 7 months. Immunohistochemical evaluations at 9 months consistently demonstrated the existence of cells positive for DAT and other A9 dopaminergic neuron markers in the engrafted striatum. These data suggest that transplantation of differentiated autologous MSCs may represent a safe and effective cell therapy for Parkinson’s disease.     

Immunotherapy targeting glioma stem cells – insights and perspectives

Introduction: Glioblastoma multiforme (GBM) is the most aggressive and lethal primary malignant brain tumor. Although progress has been made in current conventional therapies for GBM patients, the effect of these advances on clinical outcomes has been disappointing. Recent research into the origin of cancers suggest that GBM cancer stem cells (GSC) are the source of initial tumor formation, resistance to current conventional therapeutics and eventual patient relapse. Currently, there are very few studies that apply immunotherapy to target GSC.

Areas covered: CD133, a cell surface protein, is used extensively as a surface marker to identify and isolate GSC in malignant glioma. We discuss biomarkers such as CD133, L1-cell adhesion molecule (L1-CAM), and A20 of GSC. We review developing novel treatment modalities, including immunotherapy strategies, to target GSC.

Expert opinion: There are very few reports of preclinical studies targeting GSC. Identification and validation of unique molecular signatures and elucidation of signaling pathways involved in survival, proliferation and differentiation of GSC will significantly advance this field and provide a framework for the rational design of a new generation of antigen-specific, anti-GSC immunotherapy- and nanotechnology-based targeted therapyies. Combined with other therapeutic avenues, GSC-targeting therapies may represent a new paradigm to treat GBM patients.