Biology subjects

Stepankova, K.

Publications and source records attributed to Stepankova, K..

3 recordsLinked to original sources

bioRxiv2023

Alpha 9 integrin expression enables reconstruction of the spinal cord sensory pathway.

Full recovery from spinal cord injury can only occur if the axon pathways connecting the brain and spinal cord regenerate and restore motor and sensory connections. Neither sensory nor motor axons can regenerate spontaneously in the spinal cord in mammals. This failure is partly due to the lack of suitable adhesion molecules on the sensory axons that allows them to interact with the environment of the damaged spinal cord. In this rat study, an integrin adhesion molecule along with its activator was expressed in sensory neurons using an adeno-associated viral (AAV) vector. Expression of these adhesion molecules allowed sensory axons to regenerate through the spinal cord injury and all the way back to the brainstem, restoring the sensory pathway. Treated animals regained touch sensation and sensory behaviours. The integrin ligands in the injured spinal cord are tenascin-C and osteopontin, but adult PNS and CNS neurons lack receptors to them. Sensory neurons were transduced with 9 integrin, which combines with endogenous {beta}1 as 9{beta}1 (which is a tenascin/osteopontin receptor) together with the integrin activator kindlin-1. Regeneration from sensory neurons transduced with 9integrin and kindlin-1 was examined after C4 and after T10 dorsal column lesions with C6,7 and L4.5 sensory ganglia injected with AAV1 vectors. In animals treated with 9 integrin and kindlin-1, sensory axons regenerated through tenascin-C-expressing connective tissue strands and bridges across the lesion and then re-entered the CNS tissue. Many axons regenerated rostrally to the level of the medulla. Regenerated axons were particularly visible at the border between white and grey matter in the dorsal cord. Stimulation of the median/sciatic nerve caused many neurons rostral to the injury to activate and express cFos. VGLUT1/2 staining indicated newly formed functional synapses above the lesion. Behavioural recovery was seen in heat, mechanical sensation and tape removal tests. Many axons regenerated from the thoracic lesions to the brainstem, a distance of 4-5 cm, equivalent to the length of 1 or 2 spinal segments in humans.

neuroscience↗

bioRxiv2023

Oral administration of 4-methylumbelliferone reduces glial scar and promotes anatomical plasticity

Following a spinal cord injury (SCI), chondroitin sulfate proteoglycans (CSPGs) are up-regulated at the glial scar inhibiting neuroregeneration. Under normal physiological condition, CSPGs interact with hyaluronan (HA) and other extracellular matrix on neuronal surface forming a macromolecular structure called perineuronal nets (PNNs) which regulate neuroplasticity. 4-methylumbelliferone (4-MU) has been used previously to down-regulate HA synthesis but not been tested in SCI. In this study, we have evaluated the effect of 4-MU, an inhibitor of HA, in a chronic contusion model of SCI in rats. At a dose of 1.2 g/kg/day of 4-MU, we observed not only the reduction of HA in the uninjured spinal cords after 60 days of 4-MU administration, but also a down-regulation of CS glycosaminoglycans (CS-GAGs). In order to assess the effect of 4-MU in chronic SCI, rats with T8 spinal contusion injury were fed with 4-MU or placebo for 8 weeks in combination with daily treadmill rehabilitation for 16 weeks to promote neuroplasticity. 4-MU treatment promoted significant sprouting of 5-hydroxytryptamine (5-HT) positive fibres into ventral horns and reduced the HA synthesis by astrocytes around the lesion site. While 4-MU reduced astrogliosis in chronic stage of SCI, the current dose was not sufficient to down-regulate the increased production of CS-GAGs or behavioural performance. Together, these data suggest that oral treatment with 4-MU is able to induce anatomical plasticity but further adjustment on the dosage will be required to benefit functional recovery after SCI.

neuroscience↗

bioRxiv2023

4-methylumbelliferone enhances neuroplasticity in the central nervous system: potential oral treatment for SCI

Perineuronal nets (PNNs) are specialised extracellular matrix (ECM) structures that act as key plasticity regulators to the central nervous system. Removal of PNNs using chondroitinase ABC injections restores plasticity, however, there are limitations to its application to due to its enzymatic nature. Here, we explore the use of a small molecule 4-methylumbelliferone (4-MU) as an alternative non-invasive strategy to reversibly remove PNNs and enhance plasticity. Oral administration of 4-MU for 10 days successfully and dynamically removed PNNs in vitro. While 4-MU, preferentially downregulated hyaluronan in the spinal cord, a down-regulation of chondroitin sulphate proteoglycans is also observed in the cortex. Long term administration for 8-weeks administration revealed a partial removal of PNNs, and that injury-induced mechanisms promoting cortical structural plasticity are linked to endogenous modulation of ECM molecules. 4-MU is a new tool to unravel the limits of normal and pathological PNN-mediated plasticity.

neuroscience↗