Biology subjects

Baltazar, G.

Publications and source records attributed to Baltazar, G..

4 recordsLinked to original sources

bioRxiv2025

Quieting the Storm: Hypoxia as a Strategy to Boost UC-MSC Therapies for Neonatal Hypoxic-Ischemic Encephalopathy

Integrating stem cell therapies into clinical settings faces several challenges, particularly in achieving the high cell yields necessary for attaining therapeutic doses. Preconditioning with hypoxic conditions has shown promise in enhancing the UC-MSCs reparative capabilities of the central nervous system. Recent evidence suggests that oxygen concentration and exposure duration can shape MSCs phenotypes, supporting the need for further optimization of this strategy in a way to achieve maximal repair. In this study, we assessed the effects of both prolonged mild hypoxia (MH; 5% oxygen for 48 hours) and short severe hypoxia (SSH; 0.1% oxygen for 24 hours) on UC-MSCs ability to alleviate motor and cognitive deficits in a rodent model of neonatal HIE. Our results show that short, severe hypoxia led to more improvements in functional recovery than prolonged mild hypoxia, supporting that specific preconditioning parameters are crucial in maximizing UC-MSC therapeutic potential. To investigate the molecular effects of hypoxia-preconditioned MSCs in the neonatal brain post-HIE, we employed untargeted proteomics on ipsilesional brain samples from control, HIE, HIE treated with naive UC-MSCs, and HIE treated with SSH-preconditioned UC-MSCs groups, 30 days after lesion induction. This approach identified protein signatures related to injury and therapeutic intervention. Pathway enrichment analysis further revealed that administration of UC-MSCs preconditioned with short severe hypoxia significantly impacted neural signaling, protein synthesis, and energy metabolism pathways, pointing to long-term mechanisms that may support neuronal repair. These findings enhance our understanding of hypoxia-preconditioning in MSCs therapy in driving a positive therapeutic response, supporting the development of more effective and feasible treatments for neonatal HIE.

neuroscience↗

bioRxiv2025

Nose-to-Brain Healing: Hypoxia-Preconditioned Mesenchymal Stem Cells Prompt Recovery in Hypoxic-Ischemic Encephalopathy Rats

Neonatal HIE poses a significant risk factor for neurodevelopment impairment. Therapeutic hypothermia, the current standard of care for this condition, has several constraints and reduced effectivity, especially in more severe cases. Thus, it is necessary to explore novel therapeutics, like MSCs. Although previous studies report that administration of MSCs (from different sources) prompted the recovery of HIE-lesioned animals, high doses are currently used. First, this study compared the efficacy of IN versus IV administration of 50,000 UC-MSCs in a rat model of neonatal HI brain injury. For this cell dose, only IN-UC-MSC therapy reduced infarct volume, an effect accompanied by improvements of motor skills and recognition memory. Also, IN-UC-MSC administration restored myelination in the corpus callosum and mitigated glial reactivity more effectively than IV administration. In a second part of the study, to potentiate the effect of UC-MSCs administration, postnatal rats that underwent HI injury received 25,000 hypoxia-preconditioned UC-MSCs or its secretome two days later, via IN route. The administration of a low-dose of hypoxia-preconditioned UC-MSCs was sufficient to induce neurological recovery and modulation of glial response. Moreover, the administration of the secretome of these cells was enough to induce the same extent of recovery. These findings support the higher potential of IN-UC-MSC administration, compared to IV administration, while enhancing our understanding of hypoxia-preconditioning and the role of the MSCs secretome in driving a positive therapeutic response, contributing to the development of more effective and feasible treatments for neonatal HIE.

neuroscience↗

bioRxiv2023

Harnessing the power of whole human liver ex situ normothermic perfusion for preclinical AAV vector evaluation

Developing clinically predictive model systems for evaluating gene transfer and gene editing technologies has become increasingly important in the era of personalized medicine. Liver-directed gene therapies present a unique challenge due to the complexity of the human liver. In this work, we describe the application of whole human liver explants in an ex situ normothermic perfusion system to evaluate a set of fourteen natural and bioengineered adeno-associated viral (AAV) vectors directly in human liver, in the presence and absence of neutralizing human sera. Under non-neutralizing conditions, the recently developed AAV variants, AAV-SYD12 and AAV-LK03, emerged as the most functional variants in terms of cellular uptake and transgene expression. However, when assessed in the presence of human plasma containing anti-AAV neutralizing antibodies (NAbs), vectors of human origin, specifically those derived from AAV2/AAV3b, were extensively neutralized, whereas AAV8-derived variants performed efficiently. This study establishes the use of normothermic liver perfusion as an invaluable preclinical model for evaluating liver-targeted gene therapies and providing guidance for making essential decisions that promote the most effective translational programs.

molecular biology↗

bioRxiv2021

Nucleus accumbens neurons encode initiation and vigor of reward approach behavior

The nucleus accumbens (NAc) is considered an interface between motivation and action, with NAc neurons playing an important role in promoting reward approach. However, the encoding by NAc neurons that contribute to this role remains unknown. Here, we trained male rats to find rewards in an 8-arm radial maze. The activity of 62 neurons, mostly in the shell of the NAc, were recorded while rats ran towards each reward place. General linear model (GLM) analysis showed that variables related to the vigor of the locomotor approach, like speed and acceleration, and the fraction of the approach run completed were the best predictors of the firing rate for most NAc neurons. Nearly 23% of the recorded neurons, here named locomotion-off cells, were inhibited during the entire approach run, suggesting that reduction in firing of these neurons promotes initiation of locomotor approach. Another 24% of the neurons presented a peak of activity during acceleration followed by a valley during deceleration (peak-valley cells). Together, these neurons accounted for most of the speed and acceleration encoding identified in the GLM analysis. Cross-correlations between firing and speed indicated that the spikes of peak-valley cells were followed by increases in speed, suggesting that the activity of these neurons drives acceleration. In contrast, a further 19% of neurons presented a valley during acceleration followed by a peak just prior to or after reaching reward (valley-peak cells). These findings suggest that these three classes of NAc neurons control the initiation and vigor of the locomotor approach to reward. Significance StatementDeciphering the mechanisms by which the NAc controls the vigor of motivated behavior is critical to better understand and treat psychiatric conditions in which motivation is dysregulated. Manipulations of the NAc profoundly impair subjects ability to spontaneously approach reward-associated locations, preventing them from exerting effort to obtain reward. Here, we identify for the first time specific activity of NAc neurons in relation to spontaneous approach behavior. We discover three classes of neurons that could control initiation of movement and the speed vs. time trajectory during locomotor approach. These results suggest a prominent but heretofore unknown role for the NAc in regulating the kinematics of reward approach locomotion.

neuroscience↗