Modelling human CNS injury with human neural stem cells in 2- and 3-Dimensional cultures.

The adult human central nervous system (CNS) has very limited regenerative capability, and injury at the cellular and molecular level cannot be studied in vivo. Modelling neural damage in human systems is crucial to identifying species-specific responses to injury and potentially neurotoxic compounds leading to development of more effective neuroprotective agents. Hence we developed human neural stem cell (hNSC) 3-dimensional (3D) cultures and tested their potential for modelling neural insults, including hypoxic-ischaemic and Ca2+-dependent injury. Standard 3D conditions for rodent cells support neuroblastoma lines used as human CNS models, but not hNSCs, but in all cases changes in culture architecture alter gene expression. Importantly, response to damage differs in 2D and 3D cultures and this is not due to reduced drug accessibility. Together, this study highlights the impact of culture cytoarchitecture on hNSC phenotype and damage response, indicating that 3D models may be better predictors of in vivo response to damage and compound toxicity.

Chondrogenic differentiation of adipose tissue-derived stem cells within nanocaged POSS-PCU scaffolds: a new tool for nanomedicine.

Scaffold cellularization for cartilage engineering can aid implant properties, their retention and minimize repeated intervention, particularly in paediatric reconstructive craniofacial surgery. We developed novel bionanoscaffolds using paediatric adipose tissue-derived stem cells (hADSCs), an accessible autologous cell source, and POSS-PCU. Little is known about cellular responses to this nanomaterial, though it was used in human. We assessed: 1) POSS-PCU cellularization and bioaffinity to hADSCs; 2) hADSC chondrogenic differentiation ability in POSS-PCU; 3) whether bionanoscaffolds became encased within a vascular network and/or vascularised. POSS-PCU supported ADSC survival and proliferation and their migration and differentiation into cartilage within the nanoscaffold. Furthermore, after CAM-grafting, bionanoscaffolds were rapidly surrounded by blood vessels without any apparent negative reaction and erythrocytes of host origin were detected inside the scaffold, suggesting invasion from some capillaries. Altogether, this study demonstrates that POSS-PCU displays excellent bioactivity and hADSC/POSS-PCU bionanoscaffolds offer much promise for autologous cell-based tissue engineering for clinical applications. FROM THE CLINICAL EDITOR: In this study, human adipose tissue derived stem cells were used in combination with POSS-PCU nanoscaffolds to generate cartilage tissue demonstrating excellent bioactivity for autologous cell-based tissue engineering for clinical applications.

Cord blood Lin(-)CD45(-) embryonic-like stem cells are a heterogeneous population that lack self-renewal capacity.

Human umbilical cord blood (hUCB) has been proposed to contain not only haematopoietic stem cells, but also a rare pluripotent embryonic-like stem cell (ELSc) population that is negative for hematopoietic markers (Lin(-)CD45(-)) and expresses markers typical of pluripotent cells. The aim of this work was to isolate, characterise and expand this ELSc fraction from hUCB, as it may provide a valuable cell source for regenerative medicine applications. We found that we could indeed isolate a Lin(-)CD45(-) population of small cells (3-10 µm diameter) with a high nucleus to cytoplasm ratio that expressed the stem cell markers CD34 and CXCR4. However, in contrast to some previous reports, this fraction was not positive for CD133. Furthermore, although these cells expressed transcripts typical of pluripotent cells, such as SOX2, OCT3/4, and NANOG, they were not able to proliferate in any of the culture media known to support stem cell growth that we tested. Further analysis of the Lin(-)CD45(-) population by flow cytometry showed the presence of a Lin(-)CD45(-)Nestin(+) population that were also positive for CD34 (20%) but negative for CXCR4. These data suggest that the Lin(-)CD45(-) stem cell fraction present in the cord blood represents a small heterogeneous population with phenotypic characteristics of stem cells, including a Lin(-)CD45(-)Nestin(+) population not previously described. This study also suggests that heterogeneity within the Lin(-)CD45(-) cell fraction is the likely explanation for differences in the hUCB cell populations described by different groups that were isolated using different methods. These populations have been widely called "embryonic-like stem cell" on the basis of their phenotypical similarity to embryonic stem cells. However, the fact they do not seem to be able to self-renew casts some doubt on their identity, and warns against defining them as "embryonic-like stem cell" at this stage.