Integration of functional bacterial artificial chromosomes into human cord blood-derived multipotent stem cells

Autologous stem cell transplant with gene therapy for Friedreich ataxia

We advance the overarching hypothesis that stem cell therapy is a potent treatment for Friedreich's ataxia (FRDA). Here, we discuss the feasibility of autologous transplantation in FRDA, highlighting the need for the successful isolation of the FRDA patient's bone marrow-derived mesenchymal stem cells, followed by characterization that these cells maintain the GAA repeat expansion and the reduced FXN mRNA expression, both hallmark features of FRDA. Next, we discuss the need for assessment of the proliferative capability and pluripotency of FRDA patient's bone marrow-derived mesenchymal stem cells. In particular, we view the need for characterizing the in vitro differentiation of bone marrow-derived mesenchymal stem cells into the two cell types primarily affected in FRDA, peripheral neurons and cardiomyocytes. Finally, we discuss the need to test the application of bone marrow-derived mesenchymal stem cells as potent autologous donor cells for FRDA. The demonstration of the functional correction of the mutated gene in these cells will be a critical endpoint of determining the potential of stem cell therapy in FRDA. We envision a gene-based cell transplant strategy as a likely therapeutic approach for FRDA, involving stable insertion of functional human bacterial artificial chromosomes or BACs containing the intact FXN gene into stem cells, thereafter leading to the expression of frataxin protein in differentiated neurons/cardiomyocytes.

Generation of induced pluripotent stem cell lines from Friedreich ataxia patients

Friedreich ataxia (FRDA) is an autosomal recessive disorder characterised by neurodegeneration and cardiomyopathy. It is caused by a trinucleotide (GAA) repeat expansion in the first intron of the FXN gene that results in reduced synthesis of FXN mRNA and its protein product, frataxin. We report the generation of induced pluripotent stem (iPS) cell lines derived from skin fibroblasts from two FRDA patients. Each of the patient-derived iPS (FA-iPS) cell lines maintain the GAA repeat expansion and the reduced FXN mRNA expression that are characteristic of the patient. The FA-iPS cells are pluripotent and form teratomas when injected into nude mice. We demonstrate that following in vitro differentiation the FA-iPS cells give rise to the two cell types primarily affected in FRDA, peripheral neurons and cardiomyocytes. The FA-iPS cell lines have the potential to provide valuable models to study the cellular pathology of FRDA and to develop high-throughput drug screening assays. We have previously demonstrated that stable insertion of a functional human BAC containing the intact FXN gene into stem cells results in the expression of frataxin protein in differentiated neurons. As such, iPS cell lines derived from FRDA patients, following correction of the mutated gene, could provide a useful source of immunocompatible cells for transplantation therapy.

Stimulation of Activin A/Nodal signaling is insufficient to induce definitive endoderm formation of cord blood-derived unrestricted somatic stem cells

Introduction

Unrestricted somatic stem cells (USSC) derived from umbilical cord blood are an attractive alternative to human embryonic stem cells (hESC) for cellular therapy. USSC are capable of forming cells representative of all three germ line layers. The aim of this study was to determine the potential of USSC to form definitive endoderm following induction with Activin A, a protein known to specify definitive endoderm formation of hESC.

Methods

USSC were cultured for (1) three days with or without 100 ng/ml Activin A in either serum-free, low-serum or serum-containing media, (2) three days with or without 100 ng/ml Activin A in combination with 10 ng/ml FGF4 in pre-induction medium, or (3) four days with or without small molecules Induce Definitive Endoderm (IDE1, 100 nM; IDE2, 200 nM) in serum-free media. Formation of definitive endoderm was assessed using RT-PCR for gene markers of endoderm (Sox17, FOXA2 and TTF1) and lung epithelium (surfactant protein C; SPC) and cystic fibrosis transmembrane conductance regulator; CFTR). The differentiation capacity of Activin A treated USSC was also assessed.

Results

Activin A or IDE1/2 induced formation of Sox17+ definitive endoderm from hESC but not from USSC. Activin A treated USSC retained their capacity to form cells of the ectoderm (nerve), mesoderm (bone) and endoderm (lung). Activin A in combination with FGF4 did not induce formation of Sox17+ definitive endoderm from USSC. USSC express both Activin A receptor subunits at the mRNA and protein level, indicating that these cells are capable of binding Activin A.

Conclusions

Stimulation of the Nodal signaling pathway with Activin A or IDE1/2 is insufficient to induce definitive endoderm formation from USSC, indicating that USSC differ in their stem cell potential from hESC.

Umbilical cord blood cell transplantation after brain ischemia--from recovery of function to cellular mechanisms

Cell transplantation has been proposed as a potential approach to the treatment of neurological disorders. One cell population of interest consists of human umbilical cord blood (hUCB) cells, which have previously been shown to be useful for reparative medicine in haematological diseases. However, hUCB cells are also capable of differentiating into various non-haematopoietic cells, including those of the neural lineage. Moreover, hUCB cells can secrete numerous neurotrophic factors and modulate immune function and inflammatory reaction. Several studies on animal models of ischemic brain injury have demonstrated the potential of hUCB cells to minimize damage and promote recovery after ischemic brain injury.This review focuses on the treatment of both stroke and perinatal hypoxic-ischemic brain injury using hUCB cells. We discuss the therapeutic effects demonstrated after hUCB cell transplantation and emphasize possible mechanisms counteracting pathophysiological events of ischemia, thus leading to the generation of a regenerative environment that allows neural plasticity and functional recovery. The therapeutic functional effects of hUCB cells observed in animal models make the transplantation of hUCB cells a promising experimental approach in the treatment of ischemic brain injury. Together with its availability, low risk of transplantation, immaturity of cells, and simple route of application, hUCB transplantation may stand a good chance of being translated into a clinical setting for the therapy of ischemic brain injury.

Unrestricted somatic stem cells from human umbilical cord blood grow in serum-free medium as spheres

Background

Human umbilical cord blood-derived unrestricted somatic stem cells (USSCs), which are capable of multilineage differentiation, are currently under investigation for a number of therapeutic applications. A major obstacle to their clinical use is the fact that in vitro expansion is still dependent upon fetal calf serum, which could be a source of pathogens. In this study, we investigate the capacity of three different stem cell culture media to support USSCs in serum-free conditions; HEScGRO™, PSM and USSC growth medium^ACF. Our findings demonstrate that USSCs do not grow in HEScGRO™ or PSM, but we were able to isolate, proliferate and maintain multipotency of three USSC lines in USSC growth medium^ACF.

Results

For the first one to three passages, cells grown in USSC growth medium^ACF proliferate and maintain their morphology, but with continued passaging the cells form spherical cell aggregates. Upon dissociation of spheres, cells continue to grow in suspension and form new spheres. Dissociated cells can also revert to monolayer growth when cultured on extracellular matrix support (fibronectin or gelatin), or in medium containing fetal calf serum. Analysis of markers associated with pluripotency (Oct4 and Sox2) and differentiation (FoxA2, Brachyury, Goosecoid, Nestin, Pax6, Gata6 and Cytokeratin 8) confirms that cells in the spheres maintain their gene expression profile. The cells in the spheres also retain the ability to differentiate in vitro to form cells representative of the three germline layers after five passages.

Conclusions

These data suggest that USSC growth medium^ACF maintains USSCs in an undifferentiated state and supports growth in suspension. This is the first demonstration that USSCs can grow in a serum- and animal component-free medium and that USSCs can form spheres.