Differentiation potential of human adipose tissue derived stem cells into photoreceptors through explants culture and enzyme methods.

AIM: To investigate the retinal photoreceptor differentiation potential of human orbital adipose tissue-derived stem cells (ADSCs) generated by enzyme (EN) and explant (EX) culture methods. METHODS: We investigated potentials of human orbital ADSCs to differentiate into photoreceptors through EN and EX culture methods. EN and EX orbital ADSCs were obtained from the same donor during rehabilitative orbital decompression, and then were subject to a 3-step induction using Noggin, DKK-1, IGF-1 and b-FGF at different time points for 38d. Stem cell, eye-field and photoreceptor-related gene and protein markers were measured by reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescent (IMF) staining. RESULTS: Both EX and EN orbital ADSCs expressed CD133, a marker of cell differentiation. Moreover, PAX6 and rhodopsin, markers of the retinal progenitor cells, were detected from EX and EN orbital ADSCs. In EX orbital ADSCs, PAX6 mRNA was detected on the 17th day and then the rhodopsin mRNA was detected on the 24th day. In contrast, the EN orbital ADSCs expressed PAX6 and rhodopsin mRNA on the 31st day. EX orbital ADSCs expressed rhodopsin protein on the 24th day, while EN orbital ADSCs expressed rhodopsin protein on the 31st day. CONCLUSION: Orbital ADSCs isolated by direct explants culture show earlier and stronger expressions of markers towards eye field and retinal photoreceptor differentiation than those generated by conventional EN method.

Evaluation of intracellular labeling with micron-sized particles of iron oxide (MPIOs) as a general tool for in vitro and in vivo tracking of human stem and progenitor cells.

Magnetic resonance imaging (MRI)-based tracking is increasingly attracting attention as a means of better understanding stem cell dynamics in vivo. Intracellular labeling with micrometer-sized particles of iron oxide (MPIOs) provides a practical MRI-based approach due to superior detectability relative to smaller iron oxide particles. However, insufficient information is available about the general utility across cell types and the effects on cell vitality of MPIO labeling of human stem cells. We labeled six human cell types from different sources: mesenchymal stem cells derived from bone marrow (MSCs), mesenchymal stem cells derived from adipose tissue (ASCs), presumptive adult neural stem cells (ad-NSCs), fetal neural progenitor cells (f-NPCs), a glioma cell line (U87), and glioblastoma tumor stem cells (GSCs), with two different sizes of MPIOs (0.9 and 2.84 µm). Labeling and uptake efficiencies were highly variable among cell types. Several parameters of general cell function were tested in vitro. Only minor differences were found between labeled and unlabeled cells with respect to proliferation rate, mitotic duration, random motility, and capacity for differentiation to specific phenotypes. In vivo behavior was tested in chicken embryos and severe combined immunodeficient (SCID) mice. Postmortem histology showed that labeled cells survived and could integrate into various tissues. MRI-based tracking over several weeks in the SCID mice showed that labeled GSCs and f-NPCs injected into the brain exhibited translocations similar to those seen for unlabeled cells and as expected from migratory behavior described in previous studies. The results support MPIO-based cell tracking as a generally useful tool for studies of human stem cell dynamics in vivo.

Transmembrane protein 18 enhances the tropism of neural stem cells for glioma cells.

The failure of current glioma therapies is mainly due to the ability of the tumor cells to invade extensively the surrounding healthy brain tissue, hence escaping localized treatments. Neural stem cells (NSC) are able to home in on tumor foci at sites distant from the main tumor mass, possibly enabling treatment of scattered glioma clusters. To make the strategy more effective, we performed a cDNA expression library screening to identify the candidate genes that once overexpressed would enhance the tropism of NSCs for gliomas. Here, we show that a previously unannotated gene, the one encoding transmembrane protein 18 (TMEM18), is one such gene. Overexpression of TMEM18 was seen in the current study to provide NSCs and neural precursors an increased migration capacity toward glioblastoma cells in vitro and in the rat brain. Functional inactivation of the TMEM18 gene resulted in almost complete loss of the migration activity of these cells. Thus, TMEM18 is a novel cell migration modulator. Overexpression of this protein could be favorably used in NSC-based glioma therapy.