Biology subjects

Martinez-Curiel, R.

Publications and source records attributed to Martinez-Curiel, R..

4 recordsLinked to original sources

bioRxiv2026

Ex vivo astrocyte-to-oligodendrocyte conversion in human adult cortical tissue using transcription factor overexpression

Multiple sclerosis (MS) is an autoimmune and neurological disorder characterized by myelin disruption and neuronal degeneration. Currently approved therapies focus on symptom relief but do not promote central nervous system (CNS) repair. In contrast, astrocytes proliferate and repopulate MS-related lesions. Moreover, in active lesions, they hinder regenerative processes such as neural progenitor migration. Here, we propose astrocytes as a potential target for myelin repair in the human diseased brain. To achieve this aim, we investigated whether glial fibrillary acidic protein (GFAP)+ astrocytes can be transdifferentiated into oligodendrocyte lineage cells through forced overexpression of transcription factors both in vitro and ex vivo organotypic cultures of human adult cortex. Our results show that overexpression of OLIG2 and SOX10 in human induced pluripotent stem cell-derived astrocytes gives rise to oligodendrocyte progenitor cells 12 days post-induction, as shown by morphological changes and O4 marker expression. Importantly, transdifferentiation of GFAP-expressing endogenous astrocytes in human adult cortical tissue give rise to mature oligodendrocytes, as shown by expression of CC1, after only 12 days of overexpression of OLIG2 and SOX10. To our knowledge, this is the first study to assess direct astrocyte-to-oligodendrocyte reprogramming in a human platform preserving the native three-dimensional architecture of the brain. Further work will be required to determine whether the reprogrammed cells can myelinate axons and to evaluate the potential of this approach for structural and functional repair in the demyelinated human CNS.

neuroscience↗

bioRxiv2025

Intracortical transplantation of human induced pluripotent stem cell-derived progenitors ameliorates delayed thalamic degeneration following cortical stroke

Cortical ischemic stroke can trigger secondary neurodegeneration in remote brain regions connected to the primary lesion, particularly the thalamus. Although secondary thalamic degeneration is well established, the temporal relationship among early disruption of the thalamocortical pathway, neuronal degeneration, neuroinflammation, and delayed thalamic atrophy remains incompletely defined. Here, we investigated the longitudinal progression of secondary thalamic degeneration after cortical stroke, with particular emphasis on diffusion MRI tractography to monitor changes in anatomically defined thalamocortical pathways. We further determined whether early intracortical transplantation of human induced pluripotent stem cell (hiPSC)-derived neuronal progenitors could protect the remote thalamus and preserve thalamocortical connectivity.Cortical ischemic stroke was induced by distal middle cerebral artery occlusion in rats, and animals were assessed at multiple time points up to 6 months after stroke using longitudinal volumetric MRI and diffusion MRI tractography, combined with histological analyses of neuronal degeneration and microglial activation. The cortical infarct was established within 3-4 days, whereas alterations in diffusion metrics of thalamocortical pathways were detected within the first days after stroke. Neuronal degeneration in the ipsilateral ventral posterior nucleus (VPN) was evident at 2 weeks and preceded measurable VPN atrophy, which began at 3 months. Microglial activation also peaked at 2 weeks, coinciding with the onset of neuronal degeneration. Early intracortical transplantation of cortically primed hiPSC-derived neuronal progenitors 48 h after stroke did not alter cortical infarct volume but preserved VPN neurons, reduced subsequent thalamic atrophy, and maintained diffusion properties of affected thalamocortical pathways.These findings define secondary thalamic degeneration as a temporally ordered process in which early alterations in the thalamocortical pathway precede neuronal loss and delayed structural atrophy. Importantly, longitudinal tractography monitored both cortical stroke-induced thalamocortical degeneration and its modification by hiPSC-derived neuronal transplantation, establishing an in vivo approach to assess remote circuit degeneration and transplantation-dependent neuroprotection after cortical stroke.

neuroscience↗

bioRxiv2024

Human cortical neurons rapidly generated by direct ES cell programming integrate into stroke-injured rat cortex

Stroke is a major cause of long-term disability in adult humans, the neuronal loss leading to motor, sensory, and cognitive impairments. Replacement of dead neurons by intracerebral transplantation of stem cell-derived neurons for reconstruction of injured neuronal networks has potential to become a novel therapeutic strategy to promote functional recovery after stroke. Here we describe a rapid and efficient protocol for the generation of cortical neurons via direct programming of human embryonic stem (hES) cells. Our results show that 7 days overexpression of the transcription factor neurogenin 2 (NGN2) in vitro was enough to generate hES-induced cells with cortical phenotype, as revealed by immunocytochemistry and RT-qPCR, and electrophysiological properties of neurons in an intermediate stage of maturity. At 3 months after translantation into the stroke-injured rat cortex, the hES-induced neurons (hES-iNs) showed immunocytochemical markers of mature layer-specific cortical neurons and sent widespread axonal projections to several areas in both hemispheres of the host brain. Their axons became myelinated and formed synaptic contacts with host neurons, as shown by immunoelectron microscopy. Our findings demonstrate for the first time that direct transcription factor programming of hES cells can efficiently and rapidly produce cortical neurons with capacity to integrate into the stroke-injured brain.

neuroscience↗

bioRxiv2023

Oligodendrocytes in human iPS cell-derived cortical grafts remyelinate adult rat and human cortical neurons

Neuronal loss and axonal demyelination underlie long-term functional impairments in patients affected by brain disorders such as ischemic stroke. Stem cell-based approaches reconstructing and remyelinating brain neural circuitry, leading to recovery, are highly warranted. Here we demonstrate the in vitro and in vivo production of myelinating oligodendrocytes from a human induced pluripotent stem (iPS) cell-derived long-term neuroepithelial stem (lt-NES) cell line, which also gives rise to neurons with the capacity to integrate into stroke-injured, adult rat cortical networks. Most importantly, the generated oligodendrocytes survive and form myelin ensheathing human axons in the host tissue after grafting onto adult human cortical organotypic cultures. This lt-NES cell line is the first human stem cell source that after intracerebral delivery can repair both injured neural circuitries and demyelinated axons. Our findings provide supportive evidence for the potential future use of human iPS cell-derived cell lines to promote effective clinical recovery following brain injuries.

neuroscience↗