Ruzhang Jiang

Identification of tumorigenic retinal stem-like cells in human solid retinoblastomas.

Retinoblastoma (RB) is the most common malignant tumor of the retina in human children. Although it has been hypothesized for a long time that RB derives from multipotent retinal stem cells (RSCs) or retinoblasts, the direct evidence that the presence of tumorigenic RSCs in RB tumors is still lacking. Some studies indicate that malignant tumors contain tumor stem cells similar to their normal tissue stem cell counterparts. With in vitro culture and differentiation method we demonstrate that tumorigenic retinal stem‐like cells (RSLCs) indeed exist in RB lesions and that RB tumor‐derived cultures encompass undifferentiated cells capable of extensive proliferation as clonal nonadherent neurospheres and can differentiate into different retinal cells in vitro. Interestingly, cultured cells expressed retinal development related genes including nestin, CD133, pax6, chx10 and Rx, and overexpressed Bmi‐1, a gene required for self‐renewal and proliferation of stem cells. Significantly, when these cultured cells were intraocularly transplanted into SCID mice, they gave rise to new tumors with histomorphological features and immunophenotypes similar to their parental primary RBs. The results show that RBs contain tumorigenic RSLCs that contribute to tumorigenesis. This study provides a new insight to investigate the histogenesis of RBs and establishes a model for other RB research.

Role of MEF feeder cells in direct reprogramming of mousetail-tip fibroblasts

Pluripotent stem cells can be induced from somatic cells by the transcription factors Oct3/4, Sox2, c‐Myc and Klf4 when co‐cultured with mouse embryonic fibroblast (MEF) feeder cells. To date, the role of the feeder cells in the reprogramming process remains unclear. In this study, using a comparative analysis, we demonstrated that MEF feeder cells did not accelerate reprogramming or increase the frequency of induced pluripotent stem (iPS) cell colonies. However, feeder conditions did improve the growth of primary iPS colonies and were necessary for passaging the primary colonies after reprogramming was achieved. We further developed a feeder‐free culture system for supporting iPS growth and sustaining pluripotency by adding bFGF and activin A (bFA) to the medium. These data will facilitate the generation of human iPS cells without animal feeders for regenerative medicine.

Cholinergic neuronal differentiation of bone marrow mesenchymal stem cells in rhesus monkeys

The purpose of the present study was to determine the best cholinergic neuronal differentiation method of rhesus monkey bone marrow mesenchymal stem cells (BMSCs). Four methods were used to induce differentiation, and the groups were assigned accordingly: basal inducing group (culture media, bFGF, and forskolin); SHH inducing group (SHH, inducing group); RA inducing group (RA, basal inducing group); and SHH+RA inducing group (SHH, RA, and basal inducing group). All groups displayed neuronal morphology and increased expression of nestin and neuron-specific enolase. The basal inducing group did not express synapsin, and cells from the SHH inducing group did not exhibit neuronal resting membrane potential. In contrast, results demonstrated that BMSCs from the RA and SHH+RA inducing groups exhibited neuronal resting membrane potential, and cells from the SHH+RA inducing group expressed higher levels of synapsin and acetylcholine. In conclusion, the induction of cholinergic differentiation through SHH+RA was determined to be superior to the other methods.

Induced differentiation of bone marrow mesenchymal stem cells towards retinal ganglion precursor cells

Induced differentiation of bone marrow mesenchymal stem cells towards retinal ganglion precursor cells

A potential model for studying the plasticity and reprogramming of human epidermal stem cells through preimplantation blastocyst microinjection

Microinjection of adult stem cells (ASCs) into blastocysts provides a classic model for studying ASC plasticity. To explore the molecular mechanisms that govern the reprogramming of ASCs, we evaluated the experimental model through microinjection of human epidermal stem cells (hEpiSCs) into mouse blastocysts. Mouse blastocysts underwent regular embryogenesis after microinjection of allogeneic cells, confirmed by morphological observation and embryo cell counting. hEpiSCs survive and integrate into mouse embryos, by monitoring the migration of injected cells at 2, 4, 12, 16 and 24 h. In this xenogeneic system, hEpiSCs could be reprogrammed within 24 h, as evidenced by the silencing of CK15 and Integrinβ1 gene expression, without activation of Oct4 and Nanog. Microinjection of hEpiSCs into mouse blastocysts provides an efficient model for studying the molecular mechanisms of their plasticity. Moreover, the possibility of inducing pluripotent stem cells without transgenes or viruses can be entertained.