Stem cell therapy and cellular engineering for treatment of neuronal dysfunction in Huntington's disease

Dermal Fibroblast Cell Line from a Patient with the Huntington's Disease as a Promising Model for Studying Disease Pathogenesis: Production and Characterization

Huntington's disease (HD) is an incurable hereditary disease caused by expansion of the CAG repeats in the HTT gene encoding the mutant huntingtin protein (mHTT). Despite numerous studies in cellular and animal models, the mechanisms underlying the biological role of mHTT and its toxicity to striatal neurons have not yet been established and no effective therapy for HD patients has been developed so far. We produced and characterized a new line of dermal fibroblasts (HDDF, Huntington's disease dermal fibroblasts) from a patient with a confirmed HD diagnosis. We also studied the growth characteristics of HDDF cells, stained them for canonical markers, karyotyped these cells, and investigated their phenotype. HDDF cells was successfully reprogrammed into induced striatal neurons via transdifferentiation. The new fibroblast line can be used as a cell model to study the biological role of mHTT and manifestations of HD pathogenesis in both fibroblasts and induced neuronal cells obtained from them by reprogramming techniques.

Human dental stem cell derived transgene-free iPSCs generate functional neurons via embryoid body-mediated and direct induction methods

Induced pluripotent stem cells (iPSCs) give rise to neural stem/progenitor cells, serving as a good source for neural regeneration. Here, we established transgene-free (TF) iPSCs from dental stem cells (DSCs) and determined their capacity to differentiate into functional neurons in vitro. Generated TF iPSCs from stem cells of apical papilla and dental pulp stem cells underwent two methods-embryoid body-mediated and direct induction, to guide TF-DSC iPSCs along with H9 or H9 Syn-GFP (human embryonic stem cells) into functional neurons in vitro. Using the embryoid body-mediated method, early stage neural markers PAX6, SOX1, and nestin were detected by immunocytofluorescence or reverse transcription-real time polymerase chain reaction (RT-qPCR). At late stage of neural induction measured at Weeks 7 and 9, the expression levels of neuron-specific markers Nav1.6, Kv1.4, Kv4.2, synapsin, SNAP25, PSD95, GAD67, GAP43, and NSE varied between stem cells of apical papilla iPSCs and H9. For direct induction method, iPSCs were directly induced into neural stem/progenitor cells and guided to become neuron-like cells. The direct method, while simpler, showed cell detachment and death during the differentiation process. At early stage, PAX6, SOX1 and nestin were detected. At late stage of differentiation, all five genes tested, nestin, βIII-tubulin, neurofilament medium chain, GFAP, and Nav, were positive in many cells in cultures. Both differentiation methods led to neuron-like cells in cultures exhibiting sodium and potassium currents, action potential, or spontaneous excitatory postsynaptic potential. Thus, TF-DSC iPSCs are capable of undergoing guided neurogenic differentiation into functional neurons in vitro, thereby may serve as a cell source for neural regeneration.

Is there a place for human fetal-derived stem cells for cell replacement therapy in Huntington's disease?

Huntington's disease (HD) is a neurodegenerative disease that offers an excellent paradigm for cell replacement therapy because of the associated relatively focal cell loss in the striatum. The predominant cells lost in this condition are striatal medium spiny neurons (MSNs). Transplantation of developing MSNs taken from the fetal brain has provided proof of concept that donor MSNs can survive, integrate and bring about a degree of functional recovery in both pre-clinical studies and in a limited number of clinical trials. The scarcity of human fetal tissue, and the logistics of coordinating collection and dissection of tissue with neurosurgical procedures makes the use of fetal tissue for this purpose both complex and limiting. Alternative donor cell sources which are expandable in culture prior to transplantation are currently being sought. Two potential donor cell sources which have received most attention recently are embryonic stem (ES) cells and adult induced pluripotent stem (iPS) cells, both of which can be directed to MSN-like fates, although achieving a genuine MSN fate has proven to be difficult. All potential donor sources have challenges in terms of their clinical application for regenerative medicine, and thus it is important to continue exploring a wide variety of expandable cells. In this review we discuss two less well-reported potential donor cell sources; embryonic germ (EG) cells and fetal neural precursors (FNPs), both are which are fetal-derived and have some properties that could make them useful for regenerative medicine applications.

Selection of chemotactic adipose-derived stem cells using a microfluidic gradient generator

We developed a microfluidics-based integrated method for on-chip selection of chemotactic adipose-derived stem cells.