Dynamic distribution and stem cell characteristics of Sox1-expressing cells in the cerebellar cortex

Bergmann glia cells are a discrete radial glia population surrounding Purkinje cells in the cerebellar cortex. Although Bergmann glia are essential for the development and correct arborization of Purkinje cells, little is known about the regulation of this cell population after the developmental phase. In an effort to characterize this population at the molecular level, we have analyzed marker expression and established that adult Bergmann glia express Soxl, Sox2 and Sox9, a feature otherwise associated with neural stem cells （NSCs）. In the present study, we have further analyzed the developmental pattern of Soxl-expressing cells in the developing cerebellum. We report that before becoming restricted to the Purkinje cell layer, Soxl-positive cells are present throughout the immature tissue, and that these cells show characteristics of Bergmann glia progenitors. Our study shows that these progenitors express Soxl, Sox2 and Sox9, a signature maintained throughout cerebellar maturation into adulthood. When isolated in culture, the Soxl-expressing cerebellar population exhibited neurosphere-forming ability, NSC-marker characteristics, and demonstrated multipotency at the clonal level. Our results show that the Bergmann glia population expresses Soxl during cerebellar development, and that these cells can be isolated and show stem cell characteristics in vitro, suggesting that they could hold a broader potential than previously thought.

In vivo analysis of hybrid hydrogels containing dual growth factor combinations,and skeletal stem cells under mechanical stimulation for bone repair

Bone tissue engineering requires a combination of materials,cells,growth factors and mechanical cues to recapitulate bone formation.In this study we evaluated hybrid hydrogels for minimally invasive bone formation by combining biomaterials with skeletal stem cells and staged release of growth factors together with mechanotransduction.Hybrid hydrogels consisting of alginate and decellularized,demineralised bone extracellular matrix(ALG/ECM)were seeded with Stro-1t human bone marrow stromal cells(HBMSCs).Dual combinations of growth factors within staged-release polylactic-co-glycolic acid(PLGA)microparticles were added to hydrogels to mimic,in part,the signalling events in bone regeneration:VEGF,TGF-β_(3),PTHrP(fast release),or BMP-2,vitamin D_(3)(slow release).Mechanotransduction was initiated using magnetic fields to remotely actuate superparamagnetic nanoparticles(MNP)targeted to TREK1 ion channels.Hybrid hydrogels were implanted subcutaneously within mice for 28 days,and evaluated for bone formation using micro-CT and histology.Control hydrogels lacking HBMSCs,growth factors,or MNP became mineralised,and neither growth factors,HBMSCs,nor mechanotransduction increased bone formation.However,structural differences in the newly-formed bone were influenced by growth factors.Slow release of BMP-2 induced thick bone trabeculae and PTHrP or VitD_(3)increased bone formation.However,fast-release of TGF-β_(3)and VEGF resulted in thin trabeculae.Mechanotransduction reversed the trabecular thinning and increased collagen deposition with PTHrP and VitD_(3).Our findings demonstrate the potential of hybrid ALG/ECM hydrogel–cell–growth factor constructs to repair bone in combination with mechanotransduction for fine-tuning bone structure.This approach may form a minimally invasive reparative strategy for bone tissue engineering applications.