Lesion-induced changes of brevican expression in the perineuronal net of the superior vestibular nucleus

Damage to the vestibular sense organs evokes static and dynamic deficits in the eye movements,posture and vegetative functions.After a shorter or longer period of time,the vestibular function is partially or completely restored via a series of processes such as modification in the efficacy of synaptic inputs.As the plasticity of adult central nervous system is associated with the alteration of extracellular matrix,including its condensed form,the perineuronal net,we studied the changes of brevican expression in the perineuronal nets of the superior vestibular nucleus after unilateral labyrinth lesion.Our results demonstrated that the unilateral labyrinth lesion and subsequent compensation are accompanied by the changing of brevican staining pattern in the perineuronal nets of superior vestibular nucleus of the rat.The reduction of brevican in the perineuronal nets of superior vestibular nucleus may contribute to the vestibular plasticity by suspending the non-permissive role of brevican in the restoration of perineuronal net assembly.After a transitory decrease,the brevican expression restored to the control level parallel to the partial restoration of impaired vestibular function.The bilateral changing in the brevican expression supports the involvement of commissural vestibular fibers in the vestibular compensation.All experimental procedures were approved by the 'University of Debrecen–Committee of Animal Welfare'(approval No.6/2017/DEMAB) and the 'Scientific Ethics Committee of Animal Experimentation'(approval No.HB/06/éLB/2270-10/2017;approved on June 6,2017).

Application of Hypoxic Exposure Combined with Osteogenic Induction for the Enhancement of Multiple Osteoinductive Capabilities in Rat Mesenchymal Cells

Objective: The enhancement of multiple functions, including osteogenesis, angiogenesis, and cell recruitment, is required for efficient bone regeneration therapy. Recently, special attention has been focused on the microenvironment of stem cells to facilitate bone regeneration. Herein, we examined the effects of various combinations of hypoxic conditions and osteogenic induction on rat mesenchymal cells, to develop a specific protocol for enhancing the multiple cellular functions beneficial to bone regeneration. Methods: Rat mesenchymal cells, isolated from bone marrow, adipose tissue, and periodontal ligament, were examined. The cells were cultured under varied conditions of O2 tension (hypoxia) and duration and timing of hypoxic exposure, with or without osteogenic induction. Consequently, four different protocols were examined by measuring the gene expression levels of Runx2, Vegfa, and Cxcl12, indicating a capability for osteogenesis, angiogenesis, and cell recruitment, respectively. Finally, the mineralization ability of the rat mesenchymal cells was assessed by quantitating their calcified nodule formation. Results: The simultaneous application of hypoxic exposure and osteogenic induction promoted Vegfa expression in all types of cells, but suppressed Runx2. In contrast, hypoxic preconditioning, followed by osteogenic induction, did not increase the expression of these genes;in fact, Vegfa expression decreased significantly. Among the various protocols, 0.5% O2 exposure for 12 h after osteogenic induction exhibited the largest fold changes of gene expression level, especially of Vegfa. Hypoxic post-conditioning enhanced the formation of calcified nodules in periodontal ligament-derived cells. Conclusion: Short-term hypoxic exposure after osteogenic induction could be used to improve the efficiency of mesenchymal cells for bone regeneration.