The Hoechst low-fluorescent profile of the side population: clonogenicity versus dye retention

Cyclodextrin-mediated formation of porous RNA nanospheres and their application in synergistic targeted therapeutics of hepatocellular carcinoma

Spherical and porous nanoparticles are ideal nanostructures for drug delivery. But currently they are mainly composed of non-degradable inorganic materials, which hinder clinical applications. Here, biological porous nanospheres using RNA as the building blocks and cyclodextrin as the adhesive were synthesized. The RNA contained the aptamer of EpCAM for targeting delivery and siRNA for gene silencing of EpCAM, while cyclodextrin could load insoluble sorafenib, the core drug of targeted therapy for hepatocellular carcinoma (HCC), through its hydrophobic cavity. After being internalized into targeted HCC cells under the assistance of the aptamer, the porous nanospheres could be degraded by the cytoplasmic Dicer enzymes, releasing siRNA and sorafenib for synergistic therapy. The synergistic efficacy of the porous RNA nanospheres has been validated at in vitro function assay, subcutaneous tumor bearing mice, and orthotopic tumor bearing mice in vivo models. In view of the broad prospects of synergy of gene therapy with chemotherapy, and the fact that RNA and cyclodextrin of the porous nanospheres can be extended to load various types of siRNA and small molecule drugs, respectively, this form of biological porous nanospheres offers opportunities for targeted delivery of suitable drugs for treatment of specific tumors.

Isolation and characterization of cancer stem cells in vitro

The cancer stem cell hypothesis is an appealing concept to account for intratumoral heterogeneity and the observation that systemic metastasis and treatment failure are often associated with the survival of a small number of cancer cells. Whilst in vivo evidence forms the foundation of this concept, in vitro methods and reagents are attractive as they offer opportunities to perform experiments that are not possible in an animal model. While there is abundant evidence that existing cancer cell lines are not reliable models of tumor heterogeneity, recent advances based on well validated novel cancer cell lines established de novo in defined serum-free media are encouraging, particularly in the study of glioblastoma multiforme. In this chapter we wish to broadly outline the process of establishing, characterizing, and managing novel cancer cell lines in defined serum-free media, and discuss the limitations and potential opportunities that may arise from these model systems.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) supports adhesion and migration of mesenchymal stem cells and tenocytes

AIM

To establish the potential of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) as a material for tendon repair.

METHODS

The biocompatibility of PHBHHx with both rat tenocytes (rT) and human mesenchymal stem cells (hMSC) was explored by monitoring adhesive characteristics on films of varying weight/volume ratios coupled to a culture atmosphere of either 21% O(2) (air) or 2% O(2) (physiological normoxia). The diameter and stiffness of PHBHHx films was established using optical coherence tomography and mechanical testing, respectively.

RESULTS

Film thickness correlated directly with weight/volume PHBHHx (r(2) = 0.9473) ranging from 0.1 mm (0.8% weight/volume) to 0.19 mm (2.4% weight/volume). Film stiffness on the other hand displayed a biphasic response which increased rapidly at values > 1.6% weight/volume. Optimal cell attachment of rT required films of ≥ 1.6% and ≥ 2.0% weight/volume PHBHHx in 2% O(2) and 21% O(2) respectively. A qualitative adhesion increase was noted for hMSC in films ≥ 1.2% weight/volume, becoming significant at 2% weight/volume in 2% O(2). An increase in cell adhesion was also noted with ≥ 2% weight/volume PHBHHx in 21% O(2). Cell migration into films was not observed.

CONCLUSION

This evaluation demonstrates that PHBHHx is a suitable polymer for future cell/polymer replacement strategies in tendon repair.

Human endometrial side population cells exhibit genotypic, phenotypic and functional features of somatic stem cells

During reproductive life, the human endometrium undergoes around 480 cycles of growth, breakdown and regeneration should pregnancy not be achieved. This outstanding regenerative capacity is the basis for women's cycling and its dysfunction may be involved in the etiology of pathological disorders. Therefore, the human endometrial tissue must rely on a remarkable endometrial somatic stem cells (SSC) population. Here we explore the hypothesis that human endometrial side population (SP) cells correspond to somatic stem cells. We isolated, identified and characterized the SP corresponding to the stromal and epithelial compartments using endometrial SP genes signature, immunophenotyping and characteristic telomerase pattern. We analyzed the clonogenic activity of SP cells under hypoxic conditions and the differentiation capacity in vitro to adipogenic and osteogenic lineages. Finally, we demonstrated the functional capability of endometrial SP to develop human endometrium after subcutaneous injection in NOD-SCID mice. Briefly, SP cells of human endometrium from epithelial and stromal compartments display genotypic, phenotypic and functional features of SSC.

Neuroblastoma cell lines contain pluripotent tumor initiating cells that are susceptible to a targeted oncolytic virus

Background

Although disease remission can frequently be achieved for patients with neuroblastoma, relapse is common. The cancer stem cell theory suggests that rare tumorigenic cells, resistant to conventional therapy, are responsible for relapse. If true for neuroblastoma, improved cure rates may only be achieved via identification and therapeutic targeting of the neuroblastoma tumor initiating cell. Based on cues from normal stem cells, evidence for tumor populating progenitor cells has been found in a variety of cancers.

Methodology/Principal Findings

Four of eight human neuroblastoma cell lines formed tumorspheres in neural stem cell media, and all contained some cells that expressed neurogenic stem cell markers including CD133, ABCG2, and nestin. Three lines tested could be induced into multi-lineage differentiation. LA-N-5 spheres were further studied and showed a verapamil-sensitive side population, relative resistance to doxorubicin, and CD133+ cells showed increased sphere formation and tumorigenicity. Oncolytic viruses, engineered to be clinically safe by genetic mutation, are emerging as next generation anticancer therapeutics. Because oncolytic viruses circumvent typical drug-resistance mechanisms, they may represent an effective therapy for chemotherapy-resistant tumor initiating cells. A Nestin-targeted oncolytic herpes simplex virus efficiently replicated within and killed neuroblastoma tumor initiating cells preventing their ability to form tumors in athymic nude mice.

Conclusions/Significance

These results suggest that human neuroblastoma contains tumor initiating cells that may be effectively targeted by an oncolytic virus.