{"id":342721,"date":"2025-10-30T08:39:26","date_gmt":"2025-10-30T08:39:26","guid":{"rendered":"https:\/\/www.europesays.com\/us\/342721\/"},"modified":"2025-10-30T08:39:26","modified_gmt":"2025-10-30T08:39:26","slug":"thiorphan-reprograms-neurons-to-promote-functional-recovery-after-spinal-cord-injury","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/us\/342721\/","title":{"rendered":"Thiorphan reprograms neurons to promote functional recovery after spinal cord injury"},"content":{"rendered":"<p>We adopted a five-step pipeline to identify candidates for enhancing neural repair with a streamlined path that could lead to human testing (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig1\" target=\"_blank\" rel=\"noopener\">1a<\/a>). Step\u00a01 involves characterizing the transcriptomic state or \u2018signature\u2019 of a cell type that exhibits a beneficial biological effect. In this case, we used the transcriptome of corticospinal motor neurons that are capable of regeneration after SCI. We reported previously that, within 2\u2009weeks of SCI, the corticospinal neuron undergoes transient transcriptional reversion to an embryonic state\u2014a state in which it is capable of regenerating<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 1\" title=\"Poplawski, G. H. D. et al. Injured adult neurons regress to an embryonic transcriptional growth state. Nature 581, 77&#x2013;82 (2020).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR1\" id=\"ref-link-section-d103686477e714\" target=\"_blank\" rel=\"noopener\">1<\/a>. These data are publicly available. In Step\u20092, we perform an in silico screen to compare the regenerating corticospinal transcriptome with shifts in the transcriptome generated by more than 1,300 small molecules or compounds in the Broad CMap (<a href=\"https:\/\/bioconductor.org\/packages\/release\/data\/experiment\/html\/ConnectivityMap.html\" target=\"_blank\" rel=\"noopener\">https:\/\/bioconductor.org\/packages\/release\/data\/experiment\/html\/ConnectivityMap.html<\/a>). Drugs and small molecules in CMap have been exposed to various cell lines in vitro, and effects of these compounds on the transcriptome of the cultured cells have been characterized<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 3\" title=\"Lamb, J. et al. The Connectivity Map: using gene-expression signatures to connect small molecules, genes, and disease. Science 313, 1929&#x2013;1935 (2006).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR3\" id=\"ref-link-section-d103686477e725\" target=\"_blank\" rel=\"noopener\">3<\/a>. Thus, we searched CMap for compounds that generated transcriptomic shifts that parallel the state of regenerating corticospinal neurons. In Step\u20093, we took the lead candidates from the in silico screen and applied them to a medium-throughput in vitro assay consisting of cultures of adult motor cortex neurons; this screen became available only recently<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 2\" title=\"van Niekerk, E. A. et al. Methods for culturing adult CNS neurons reveal a CNS conditioning effect. Cell Rep. Methods 2, 100255 (2022).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR2\" id=\"ref-link-section-d103686477e729\" target=\"_blank\" rel=\"noopener\">2<\/a> and provides what could be the most useful in vitro system for predicting potential in vivo effects in the mature nervous system, because the screen consists of adult rather than embryonic or postnatal neurons. To date, in vitro cellular screens of the nervous system consisted of either embryonic or early postnatal neuronal cultures, which may not accurately reflect responses of adult central nervous system (CNS) neurons. Immortalized neural cell lines<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 4\" title=\"Whittemore, S. R. &amp; Onifer, S. M. Immortalized neural cell lines for CNS transplantation. Prog. Brain Res. 127, 49&#x2013;65 (2000).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR4\" id=\"ref-link-section-d103686477e734\" target=\"_blank\" rel=\"noopener\">4<\/a> suffer from similar limitations. Although adult dorsal root ganglia (DRG) neurons can be cultured routinely, these cells exhibit fundamentally different transcriptomes before and after injury<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 1\" title=\"Poplawski, G. H. D. et al. Injured adult neurons regress to an embryonic transcriptional growth state. Nature 581, 77&#x2013;82 (2020).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR1\" id=\"ref-link-section-d103686477e738\" target=\"_blank\" rel=\"noopener\">1<\/a>,<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 5\" title=\"Blesch, A. et al. Conditioning lesions before or after spinal cord injury recruit broad genetic mechanisms that sustain axonal regeneration: superiority to camp-mediated effects. Exp. Neurol. 235, 162&#x2013;173 (2012).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR5\" id=\"ref-link-section-d103686477e741\" target=\"_blank\" rel=\"noopener\">5<\/a>,<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 6\" title=\"Chandran, V. et al. A systems-level analysis of the peripheral nerve intrinsic axonal growth program. Neuron 89, 956&#x2013;970 (2016).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR6\" id=\"ref-link-section-d103686477e744\" target=\"_blank\" rel=\"noopener\">6<\/a> and, again, might not be accurate tools for predicting therapeutic benefits of candidate therapies for injured brain and spinal cord motor neurons. Induced pluripotent stem cells or neurons induced from other cell types also often exhibit early cellular markers<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 7\" title=\"Vadodaria, K. C., Jones, J. R., Linker, S. &amp; Gage, F. H. Modeling brain disorders using induced pluripotent stem cells. Cold Spring Harb. Perspect. Biol. 12, a035659 (2020).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR7\" id=\"ref-link-section-d103686477e748\" target=\"_blank\" rel=\"noopener\">7<\/a>. Cultures of adult neurons therefore may represent the most optimal in vitro screen developed for clinical translation<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 2\" title=\"van Niekerk, E. A. et al. Methods for culturing adult CNS neurons reveal a CNS conditioning effect. Cell Rep. Methods 2, 100255 (2022).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR2\" id=\"ref-link-section-d103686477e752\" target=\"_blank\" rel=\"noopener\">2<\/a>. Step\u20094 consists of in vivo validation of the top drug arising from the in vitro screen in a model of SCI. Finally, Step 5 consists of validating candidate compounds in cultures of adult primate cortical neurons, including human adult cortex. This step follows rather than precedes in vivo testing because of the scarcity of the primate and human neuronal resource: normal human neurons in particular are available only occasionally from surgical specimens and in our case were obtained from an individual undergoing tumour resection through a cortical window, where pathology confirmed the cortical biopsy was normal tissue. <\/p>\n<p><b id=\"Fig1\" class=\"c-article-section__figure-caption\" data-test=\"figure-caption-text\">Fig. 1: Drug discovery pipeline, in silico analysis and in vitro validation.<\/b><a class=\"c-article-section__figure-link\" data-test=\"img-link\" data-track=\"click\" data-track-label=\"image\" data-track-action=\"view figure\" href=\"https:\/\/www.nature.com\/articles\/s41586-025-09647-y\/figures\/1\" rel=\"nofollow noopener\" target=\"_blank\"><img decoding=\"async\" aria-describedby=\"Fig1\" src=\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/10\/41586_2025_9647_Fig1_HTML.png\" alt=\"figure 1\" loading=\"lazy\" width=\"685\" height=\"654\"\/><\/a><\/p>\n<p><b>a<\/b>, Drug discovery pipeline consisting of five steps: (1) creation of a transcriptomic dataset; (2) in silico analysis using CMap; (3) medium-throughput in vitro screen; (4) in vivo testing of lead candidate(s); and (5) in vitro monkey and human validation.\u00a0CST, corticospinal tract. <b>b<\/b>, In silico analysis shows ranking of compounds in CMap on the basis of\u00a0connectivity score (left y\u2009axis), specificity score (blue, right y\u2009axis) and reliability score (green, right y\u2009axis) (see text for further detail). <b>c<\/b>, Neurite extension in composite image of cortical neurons treated with DMSO control and thiorphan (250\u2009\u03bcM), Tuj1 labelling. <b>d<\/b>,<b>e<\/b>, In vitro screen of top three \u2018hits\u2019 from in silico screen, together with predicted negative modulator, adiphenine. Tested in cultures of adult mouse primary cortical neurons for 5\u2009days in vitro, three independent\u00a0biological replicates were performed on separate\u00a0days, each using neurons from four\u00a0adult\u00a0mice. For each condition, data from all neurons measured across replicates were combined to yield n\u00a0=\u00a0200 neurons per condition. Each neuron was spatially separated and analysed as an independent observation. Total neurite outgrowth per cell (Tuj1 labelling) is shown for each condition.\u00a0Median values: DMSO (82.9); thiorphan (90.7, 99.8, 132.4, 166.1); triflusal (74.3, 61.7, 94.5, 124.5); milrinone (78.9, 77.4, 68.5, 75.5); adiphenine (74.4, 44.5, 31.7, 3)\u00a0(<b>d<\/b>). Maximum neurite length per cell is shown for each condition.\u00a0Median values: DMSO (93.3); thiorphan (111.1, 105.4, 122.1, 128); triflusal (84.4, 85, 104.9, 114.3); milrinone (100.6, 81.7, 79, 78.6); adiphenine (87.4, 60, 30.6, 6.23) (<b>e<\/b>). Statistical significance was determined by two-tailed Student\u2019s t-test\u00a0(**P\u2009P\u2009d,<b>e<\/b>). Scale bar, 25 \u03bcm (<b>c<\/b>).<\/p>\n<p>Characterizing the transcriptomic state<\/p>\n<p>Step\u20091 was accomplished in this study by using our previous\u00a0data describing the transcriptome of the regenerating corticospinal neuron<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 1\" title=\"Poplawski, G. H. D. et al. Injured adult neurons regress to an embryonic transcriptional growth state. Nature 581, 77&#x2013;82 (2020).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR1\" id=\"ref-link-section-d103686477e835\" target=\"_blank\" rel=\"noopener\">1<\/a>, as referenced above.<\/p>\n<p>In silico analysis<\/p>\n<p>In silico analysis directly followed the original methodology of Lamb et al.<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 3\" title=\"Lamb, J. et al. The Connectivity Map: using gene-expression signatures to connect small molecules, genes, and disease. Science 313, 1929&#x2013;1935 (2006).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR3\" id=\"ref-link-section-d103686477e847\" target=\"_blank\" rel=\"noopener\">3<\/a>, identifying several compounds that most closely matched the expression profile of the regenerating corticospinal system (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig1\" target=\"_blank\" rel=\"noopener\">1b<\/a> and Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">1a<\/a>). A \u2018connectivity score\u2019 with a value between +1 and \u22121 described the similarity between the corticospinal transcriptomic profile and an individual compound\u2019s transcriptomic profile, where +1 was most similar and \u22121 was least similar to the corticospinal dataset (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig1\" target=\"_blank\" rel=\"noopener\">1b<\/a>). We further calculated a \u2018reliability score\u2019 for each compound that takes into account the connectivity score, P\u2009value, false detection rate (FDR), \u2018instance count\u2019 (number of experiments that include the compound), non-null score (the ratio of experiments that have a consistent score based on most experiments) and \u2018specificity score\u2019 derived from the distribution of enrichment scores for gene lists from MSigDB; see <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">Methods<\/a> for a more detailed description of the reliability score. The top compounds that met the criteria of highest enrichment, reliability and specificity scores were considered \u2018hits\u2019 in this assay and included: quinostatin (highest enrichment score +0.91\u2009\u00b1\u20090.07), thiorphan (+0.86\u2009\u00b1\u20090.11), triflusal (+0.79\u2009\u00b1\u20090.13) and milrinone (+0.78\u2009\u00b1\u20090.18), whereas adiphenine was the most negatively correlated (\u22120.78\u2009\u00b1\u20090.18; Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig1\" target=\"_blank\" rel=\"noopener\">1b<\/a> and Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">1b<\/a>). Biological annotation (<a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">Methods<\/a>) indicated that quinostatin inhibits PI3 kinase; thiorphan is a neutral endopeptidase inhibitor; triflusal inhibits nuclear factor \u03baB, phosphodiesterase and COX1, and milrinone is a phosphodiesterase inhibitor (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">1a<\/a>). Quinostatin was not available for purchase and attempts at synthesis did not yield adequate quality compound. Thiorphan has been characterized primarily as a neutral endopeptidase inhibitor targeting neprilysin<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 8\" title=\"Schwartz, J. C. et al. Enkephalin metabolism in brain and its inhibition. Prog. Neuropsychopharmacol. Biol. Psychiatry 6, 665&#x2013;671 (1982).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR8\" id=\"ref-link-section-d103686477e879\" target=\"_blank\" rel=\"noopener\">8<\/a>. It has also been linked to neuroprotective properties in models of perinatal excitotoxic brain lesions<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 9\" title=\"Medja, F. et al. Thiorphan, a neutral endopeptidase inhibitor used for diarrhoea, is neuroprotective in newborn mice. Brain 129, 3209&#x2013;3223 (2006).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR9\" id=\"ref-link-section-d103686477e884\" target=\"_blank\" rel=\"noopener\">9<\/a> and diabetic retinopathy<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 10\" title=\"Prasad, T. et al. Beneficial effects of combined AT1 receptor\/neprilysin inhibition (ARNI) versus AT1 receptor blockade alone in the diabetic eye. Invest. Ophthalmol. Vis. Sci. 57, 6722&#x2013;6730 (2016).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR10\" id=\"ref-link-section-d103686477e888\" target=\"_blank\" rel=\"noopener\">10<\/a>, and has \u03b2-amyloid degrading properties<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 11\" title=\"Hafez, D. et al. Neprilysin-2 is an important &#x3B2;-amyloid degrading enzyme. Am. J. Pathol. 178, 306&#x2013;312 (2011).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR11\" id=\"ref-link-section-d103686477e892\" target=\"_blank\" rel=\"noopener\">11<\/a>. Thiorphan, milrinone and triflusal were taken forward as positive candidates, and adiphenine was used as a negative control.<\/p>\n<p>In vitro adult motor cortical culture screen<\/p>\n<p>We assessed the lead candidate compounds in dissociated cultures of the adult (postnatal day\u200960) mouse motor cortex<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 2\" title=\"van Niekerk, E. A. et al. Methods for culturing adult CNS neurons reveal a CNS conditioning effect. Cell Rep. Methods 2, 100255 (2022).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR2\" id=\"ref-link-section-d103686477e904\" target=\"_blank\" rel=\"noopener\">2<\/a>. An average of 10,000 neurons per single motor cortex were obtained, and we quantified total neurite outgrowth and maximal neurite length per cell 5\u2009days after exposure to the candidate compounds. Several drug doses were applied (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig1\" target=\"_blank\" rel=\"noopener\">1d,e<\/a>), including the predicted negative modifier of corticospinal growth, adiphenine. Significant overall differences in neurite outgrowth were present using various compounds (drug type\u2009\u00d7\u2009dose interaction generalized estimating equation for total neurite outgrowth, Wald chi-square\u2009=\u200960.67, P\u2009P\u2009P\u20091d,e) and longest neurite length by 30% (post hoc generalized estimating equation, Wald chi-square\u2009=\u200912.62, P\u20091d,e). The effect of thiorphan was dose dependent, with peak effects occurring at doses between 100\u2009\u03bcM and 250\u2009\u03bcM. The effect of the next candidate drug for enhancing corticospinal regeneration, triflusal, was more modest, with an increase in neurite outgrowth of 30% at its peak dose of 250\u2009\u03bcM with no significant change in longest neurite length; none of these changes reached statistical significance (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig1\" target=\"_blank\" rel=\"noopener\">1e<\/a>). The third candidate in rank order, milrinone, did not significantly influence either total neurite outgrowth or longest neurite length at any dose (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig1\" target=\"_blank\" rel=\"noopener\">1d,e<\/a>). Validating the in silico screening process, the predicted negative regulator of corticospinal growth, adiphenine, strongly and significantly reduced total neurite outgrowth and longest neurite length in a dose-dependent manner (post hoc generalized estimating equation, P\u20091c\u2013e).<\/p>\n<p>In vivo testing in a\u00a0model of SCI<\/p>\n<p>Given the success of thiorphan in demonstrating efficacy in the in vitro screen, it advanced to Step\u20094: in vivo testing in a clinically relevant model of SCI. Adult Fischer 344 rats underwent severe contusive bilateral cervical SCI at the C5 spinal cord segment; mid-cervical lesions are the most common levels of human injury<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 12\" title=\"Alizadeh, A., Dyck, S. M. &amp; Karimi-Abdolrezaee, S. Traumatic spinal cord injury: an overview of pathophysiology, models and acute injury mechanisms. Front. Neurol. 10, 282 (2019).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR12\" id=\"ref-link-section-d103686477e952\" target=\"_blank\" rel=\"noopener\">12<\/a> (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">2a,b<\/a>). We then waited 2\u2009weeks\u2014a clinically relevant time to delay intervention to allow subject recovery from the acute effects of injury (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig2\" target=\"_blank\" rel=\"noopener\">2a<\/a>). Animals were then divided into one of four treatment groups: (1) lesion alone (n\u2009=\u20099), (2) thiorphan alone (n\u2009=\u200910), (3) diluent\u2009+\u2009NPC graft (n\u2009=\u20099) and (4) thiorphan\u2009+\u2009NPC graft (n\u2009=\u20099). We tested diluent\u2009+\u2009NPC grafts as a positive control in this lesion model because these cells support axonal regeneration into the lesion site, the formation of new neural relays across the injury site and partial functional recovery<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 13\" title=\"Kadoya, K. et al. Spinal cord reconstitution with homologous neural grafts enables robust corticospinal regeneration. Nat. Med. 22, 479&#x2013;487 (2016).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR13\" id=\"ref-link-section-d103686477e975\" target=\"_blank\" rel=\"noopener\">13<\/a>,<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 14\" title=\"Brock, J. H., Graham, L., Staufenberg, E., Im, S. &amp; Tuszynski, M. H. Rodent neural progenitor cells support functional recovery after cervical spinal cord contusion. J. Neurotrauma 35, 1069&#x2013;1078 (2018).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR14\" id=\"ref-link-section-d103686477e978\" target=\"_blank\" rel=\"noopener\">14<\/a>. We also compared thiorphan alone with NPCs. The combination of thiorphan\u2009+\u2009NPCs aimed to determine whether effects of both treatments were additive, thereby representing a method of further augmenting recovery after severe cervical SCI. Thiorphan was infused continuously into the left motor cortex because it does not cross the blood\u2013brain barrier. Infusions continued for 4\u2009weeks starting 2\u2009weeks after injury at a dose of 100\u2009mM (0.25\u2009\u03bcl\u2009h\u22121), based on extrapolation of in vitro dosing to in vivo dosing<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 15\" title=\"Coussens, N. P. et al. Assay guidance manual: quantitative biology and pharmacology in preclinical drug discovery. Clin. Transl. Sci. 11, 461&#x2013;470 (2018).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR15\" id=\"ref-link-section-d103686477e984\" target=\"_blank\" rel=\"noopener\">15<\/a>. An in vivo neprilysin cleavage assay confirmed the bioactivity of intraparenchymal motor cortex infusions of thiorphan over 1, 2 and 4\u2009weeks (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">2c<\/a>). Spinal cord NPC grafts were obtained from Fischer 344 embryonic-day-14 (E14) spinal cords as reported previously<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 16\" title=\"Lu, P. et al. Long-distance growth and connectivity of neural stem cells after severe spinal cord injury. Cell 150, 1264&#x2013;1273 (2012).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR16\" id=\"ref-link-section-d103686477e992\" target=\"_blank\" rel=\"noopener\">16<\/a> and injected through the dura into the lesion cavity 2\u2009weeks post SCI (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig2\" target=\"_blank\" rel=\"noopener\">2b<\/a>; <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">Methods<\/a>). Two weeks before euthanasia, the corticospinal projection was traced anterogradely using an AAV9-CAG\u2013Ruby2sm_Flag.<\/p>\n<p><b id=\"Fig2\" class=\"c-article-section__figure-caption\" data-test=\"figure-caption-text\">Fig. 2: Thiorphan improves functional outcomes after severe C5 bilateral contusion.<\/b><a class=\"c-article-section__figure-link\" data-test=\"img-link\" data-track=\"click\" data-track-label=\"image\" data-track-action=\"view figure\" href=\"https:\/\/www.nature.com\/articles\/s41586-025-09647-y\/figures\/2\" rel=\"nofollow noopener\" target=\"_blank\"><img decoding=\"async\" aria-describedby=\"Fig2\" src=\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/10\/41586_2025_9647_Fig2_HTML.png\" alt=\"figure 2\" loading=\"lazy\" width=\"685\" height=\"444\"\/><\/a><\/p>\n<p><b>a<\/b>, In vivo experimental outline of a\u00a0clinically relevant SCI model. <b>b<\/b>, Nissl stain of a\u00a0severe C5 bilateral contusion model. Sagittal section, rostral to left. Top, large contusion cavity in an\u00a0ungrafted animal after 3\u2009months. Bottom, NPC graft filling the\u00a0lesion cavity and providing substrate for potential corticospinal axon regeneration. <b>c<\/b>, Skilled forelimb successful pellet retrieval with right paw on Montoya staircase<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 23\" title=\"Montoya, C. P., Campbell-Hope, L. J., Pemberton, K. D. &amp; Dunnett, S. B. The &#x2018;staircase test&#x2019;: a measure of independent forelimb reaching and grasping abilities in rats. J. Neurosci. Methods 36, 219&#x2013;228 (1991).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR23\" id=\"ref-link-section-d103686477e1022\" target=\"_blank\" rel=\"noopener\">23<\/a>\u2009\u00b1\u2009s.e.m. Animals that received thiorphan and a substrate for axonal regeneration into the lesion site\u2014an NPC graft\u2014exhibit significant functional recovery over time compared with lesioned controls (P\u2009=\u20090.005, group\u2009\u00d7\u2009time interaction, Poisson generalized linear model). Treatment with thiorphan alone also trended towards significance (P\u2009=\u20090.14). The lesion model applied in this experiment is the most severe that we have tested, and NPC grafts also exhibited a trend towards better outcomes than lesioned controls but this did not reach statistical significance. Grey shading, period of thiorphan infusion into cortex. <b>d<\/b>, Thiorphan\u2009+\u2009NPC graft group also exhibits significant recovery of pellet retrieval accuracy in this severe lesion model (P\u2009=\u20090.001). Other treated groups trend towards improved outcomes compared with lesioned controls. Accuracy represents the number of pellets eaten divided by the number of pellets displaced plus the number of pellets eaten. *P c,<b>d<\/b>).\u00a0Scale bar, 500\u2009\u03bcm.<\/p>\n<p><a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM3\" target=\"_blank\" rel=\"noopener\">Source data<\/a><\/p>\n<p>Twelve weeks after SCI, animals treated with thiorphan\u2009+\u2009NPC grafts exhibited a significant, twofold improvement in forelimb grasping success (number of pellets grasped and eaten) after severe mid-cervical SCI compared with lesioned controls (Poisson generalized linear model, Wald chi-square\u2009=\u20097.92, P\u2009=\u20090.005; Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig2\" target=\"_blank\" rel=\"noopener\">2c<\/a>). Recipients of thiorphan alone or NPC grafts alone exhibited lesser degrees of forelimb recovery compared with lesioned controls that did not reach statistical significance (Poisson generalized linear model, Wald chi-square\u2009=\u20092.16, P\u2009=\u20090.14 comparing thiorphan with lesion alone, and Wald chi-square\u2009=\u20092.07, P\u2009=\u20090.15 comparing grafts-only with lesion alone; Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig2\" target=\"_blank\" rel=\"noopener\">2c<\/a>). The accuracy of pellet retrieval (percentage of pellets grasped that are eaten) also improved significantly in animals that received thiorphan\u2009+\u2009NPC grafts (Gamma generalized linear model, Wald chi-square\u2009=\u200910.13, P\u2009=\u20090.001) compared with lesioned controls (60% accuracy versus 30% accuracy; Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig2\" target=\"_blank\" rel=\"noopener\">2d<\/a>). Thus, as suggested by in silico and subsequent in vitro screens, thiorphan significantly improves functional outcomes when combined with neural stem cell grafts to sites of SCI by enhancing the potency of NPC grafting.<\/p>\n<p>To examine anatomical mechanisms underlying beneficial effects of thiorphan infusion on functional outcomes, we assessed corticospinal axon regeneration into stem cell grafts occupying the lesion site. Previously, we have shown that corticospinal axons regenerate into NPC grafts placed into sites of SCI and form synapses. Further, grafted NPC neurons extend axons from the lesion site to host neurons below the lesion and form synapses; consequently, new neural relays are formed across the lesion that support functional improvement<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 13\" title=\"Kadoya, K. et al. Spinal cord reconstitution with homologous neural grafts enables robust corticospinal regeneration. Nat. Med. 22, 479&#x2013;487 (2016).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR13\" id=\"ref-link-section-d103686477e1088\" target=\"_blank\" rel=\"noopener\">13<\/a>,<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" title=\"Lu, P. et al. Long-distance growth and connectivity of neural stem cells after severe spinal cord injury. Cell 150, 1264&#x2013;1273 (2012).\" href=\"#ref-CR16\" id=\"ref-link-section-d103686477e1091\">16<\/a>,<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" title=\"Rosenzweig, E. S. et al. Restorative effects of human neural stem cell grafts on the primate spinal cord. Nat. Med. 24, 484&#x2013;490 (2018).\" href=\"#ref-CR17\" id=\"ref-link-section-d103686477e1091_1\">17<\/a>,<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" title=\"Ceto, S., Sekiguchi, K. J., Takashima, Y., Nimmerjahn, A. &amp; Tuszynski, M. H. Neural stem cell grafts form extensive synaptic networks that integrate with host circuits after spinal cord injury. Cell Stem Cell 27, 430&#x2013;440 (2020).\" href=\"#ref-CR18\" id=\"ref-link-section-d103686477e1091_2\">18<\/a>,<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 19\" title=\"Koffler, J. et al. Biomimetic 3D-printed scaffolds for spinal cord injury repair. Nat. Med. 25, 263&#x2013;269 (2019).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR19\" id=\"ref-link-section-d103686477e1094\" target=\"_blank\" rel=\"noopener\">19<\/a>. In the present experiment, thiorphan significantly increased corticospinal regeneration into grafts by 60% (P\u20093a,c,e) compared with individuals that received NPC grafts alone (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig3\" target=\"_blank\" rel=\"noopener\">3b,d,e<\/a> and Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">3a,b<\/a>). Thiorphan administration in the absence of NPC grafts could not promote corticospinal regeneration into the lesion cavity because there was no cellular substrate onto which injured corticospinal axons could extend. Thin plane confocal microscopy showed colocalization of corticospinal axon terminals with synaptophysin apposed onto grafted neurons, indicating putative synapse formation from regenerating host axons to grafted neurons (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig3\" target=\"_blank\" rel=\"noopener\">3f<\/a>). Nearly all grafted animals in this experiment exhibited complete graft filling of the lesion cavity (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">4a,b<\/a>). Cortical infusion of thiorphan over 4\u2009weeks caused no damage or neuronal loss in the motor cortex (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">4c,d<\/a>).<\/p>\n<p><b id=\"Fig3\" class=\"c-article-section__figure-caption\" data-test=\"figure-caption-text\">Fig. 3: Thiorphan increases corticospinal axonal regeneration.<\/b><a class=\"c-article-section__figure-link\" data-test=\"img-link\" data-track=\"click\" data-track-label=\"image\" data-track-action=\"view figure\" href=\"https:\/\/www.nature.com\/articles\/s41586-025-09647-y\/figures\/3\" rel=\"nofollow noopener\" target=\"_blank\"><img decoding=\"async\" aria-describedby=\"Fig3\" src=\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/10\/41586_2025_9647_Fig3_HTML.png\" alt=\"figure 3\" loading=\"lazy\" width=\"685\" height=\"459\"\/><\/a><\/p>\n<p><b>a<\/b>, CST axons labelled anterogradely with Flag (red) show greater regeneration into E14 neural progenitor stem cell grafts (green (green fluorescent protein (GFP))) in animals with thiorphan cortical infusions. The white\u00a0dotted line indicates the\u00a0host\u2013graft interface; the boxed region is shown at higher magnification in <b>c<\/b>. <b>b<\/b>, Fewer corticospinal axons regenerate into animals that did not receive thiorphan cortical infusions. The white\u00a0dotted line indicates the\u00a0host\u2013graft interface; the boxed region is shown at higher magnification in <b>d<\/b>. <b>c<\/b>,<b>d<\/b>, Higher magnification views of the\u00a0boxed regions in <b>a<\/b> (<b>c<\/b>) and <b>b<\/b> (<b>d<\/b>) showing regenerating corticospinal axons. <b>e<\/b>, Corticospinal regeneration into graft occupying lesion site is increased 1.6-fold in the\u00a0presence of thiorphan infusion into the\u00a0motor cortex (*P\u2009t-test). In the absence of a graft, no host axons are present in the lesion site; non-grafted animals could not be quantified. <b>f<\/b>, Regenerating host corticospinal axons form putative synapses with grafted neurons, based on colocalization of regenerating CST (red) with synaptophysin (SYN, white) apposed to grafted neuron (GFP, green). DAPI in blue. Arrows indicate the\u00a0exact\u00a0orthogonal view intersection point,\u00a0single plane. Scale bars, 500\u2009\u03bcm (<b>a<\/b>,<b>b<\/b>); 200\u2009\u03bcm (<b>c<\/b>,<b>d<\/b>); 5\u2009\u03bcm (<b>f<\/b>).<\/p>\n<p><a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM4\" target=\"_blank\" rel=\"noopener\">Source data<\/a><\/p>\n<p>We also examined whether thiorphan treatment influenced corticospinal axonal sprouting above the lesion site: there were no significant differences in corticospinal axon density among the four animal groups (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">5a,b<\/a>). Although thiorphan was administered into the motor cortex, we also examined whether there was a difference in the growth of serotonergic or sensory (calcitonin gene-related-peptide-labelled) axons into the graft; as expected, there was no difference between thiorphan\u2009+\u2009NPC graft and the diluent\u2009+\u2009NPC grafted groups (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">6a\u2013f<\/a>). We further examined whether thiorphan administration into the cortex influenced the host\u2013graft glial border (glial fibrillary acidic protein immunoreactivity); it did not (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">7a\u2013c<\/a>). Finally, we examined whether thiorphan administration into the cortex affected graft differentiation: it did not (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">7d\u2013k<\/a>); as expected, neither did it affect graft-derived axon extension into the host (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">7l,m<\/a>). Thus, beneficial effects of thiorphan administration were detectable on the corticospinal system to which it was targeted.<\/p>\n<p>Testing in primate systems<\/p>\n<p>The final step in this process, Step 5, extended the clinical relevance of this work by determining whether thiorphan can also promote growth from adult primate motor cortex and human cortical neurons (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig4\" target=\"_blank\" rel=\"noopener\">4a\u2013c<\/a>). This step is performed last because these samples\u2014particularly normal human cortex samples\u2014are highly valuable. Human participant approval was obtained for these procedures. Neurons were isolated from the monkey M1 motor cortex, dissociated and cultured, adapted from ref. <a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 2\" title=\"van Niekerk, E. A. et al. Methods for culturing adult CNS neurons reveal a CNS conditioning effect. Cell Rep. Methods 2, 100255 (2022).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR2\" id=\"ref-link-section-d103686477e1232\" target=\"_blank\" rel=\"noopener\">2<\/a>, and treated with 100\u2009\u03bcM thiorphan for 5\u2009days in vitro (two replicates). These cultures are free of NPCs when assessed by markers such as Nestin and Sox2. Thiorphan treatment significantly increased total neurite outgrowth by 36% (P\u2009P\u20094a\u2013c). We then proceeded to culture the human cortex: normal cortex from the middle temporal gyrus of a 56-year-old man was obtained from biopsy, the tissue was dissociated and neuronal cultures established (adapted from ref. <a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 2\" title=\"van Niekerk, E. A. et al. Methods for culturing adult CNS neurons reveal a CNS conditioning effect. Cell Rep. Methods 2, 100255 (2022).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR2\" id=\"ref-link-section-d103686477e1246\" target=\"_blank\" rel=\"noopener\">2<\/a>; Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">8<\/a>). Treatment with 100\u2009\u03bcM thiorphan for 5\u2009days in vitro (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig4\" target=\"_blank\" rel=\"noopener\">4d\u2013f<\/a>) resulted in a significant increase in total neurite outgrowth by 30.3%\u2009\u00b1\u20097.3% (P\u2009P\u2009=\u20090.016) compared with controls. Thus, thiorphan retains biological activity when tested in monkey and human cortical cultures, exhibiting roughly 40% of the potency exhibited in rats in effects on total neurite outgrowth and 70% of the potency exhibited in rats in terms of longest neurite length.<\/p>\n<p><b id=\"Fig4\" class=\"c-article-section__figure-caption\" data-test=\"figure-caption-text\">Fig. 4: Thiorphan increases growth of monkey and human cortical neurons and induces pro-regenerative state.<\/b><a class=\"c-article-section__figure-link\" data-test=\"img-link\" data-track=\"click\" data-track-label=\"image\" data-track-action=\"view figure\" href=\"https:\/\/www.nature.com\/articles\/s41586-025-09647-y\/figures\/4\" rel=\"nofollow noopener\" target=\"_blank\"><img decoding=\"async\" aria-describedby=\"Fig4\" src=\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/10\/41586_2025_9647_Fig4_HTML.png\" alt=\"figure 4\" loading=\"lazy\" width=\"685\" height=\"728\"\/><\/a><\/p>\n<p><b>a<\/b>, Thiorphan significantly increased total neurite outgrowth from primary cultures of adult cynomolgus macaque motor cortex labelled for Tuj (***P\u2009t-test). Control cultures received DMSO. Each point represents the\u00a0total neurite length of individual neurons. Samples were run as technical duplicates, with neurons cultured for 5\u2009days. <b>b<\/b>, Thiorphan treatment also significantly increased the\u00a0maximum neurite length per cell by 1.8-fold (****P\u2009t-test). <b>c<\/b>, Representative images of cultures of adult primate motor cortex treated with diluent or thiorphan. <b>d<\/b>, Thiorphan significantly increased total neurite outgrowth from primary cultures of normal 56-year-old human cortex neurons labelled for Tuj (****P\u2009t-test). Neurons cultured for 5\u2009days. Each point represents\u00a0the total neurite length of one neuron. <b>e<\/b>, Thiorphan treatment of human cortical neurons also significantly increased the maximum neurite length per cell (**P\u2009t-test). <b>f<\/b>, Representative images of 56-year-old human cortical neurons in culture labelled for Tuj1. <b>g<\/b>, RNA sequencing was performed on cultures of adult primary motor cortex from rhesus monkeys treated for 5\u2009days with thiorphan or vehicle (DMSO). A total of 177 genes changed \u00b11.5-fold on a log2 scale. <b>h<\/b>, Gene ontology of these 177 genes demonstrates clear enrichment for developmental processes (Gene Ontology database<a data-track=\"click\" data-track-action=\"reference anchor\" data-track-label=\"link\" data-test=\"citation-ref\" aria-label=\"Reference 24\" title=\"Carbon, S. &amp; Mungall, C. Gene ontology data archive. Zenodo &#010;                https:\/\/doi.org\/10.5281\/zenodo.1205166&#010;                &#010;               (2025).\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#ref-CR24\" id=\"ref-link-section-d103686477e1325\" target=\"_blank\" rel=\"noopener\">24<\/a>, <a href=\"https:\/\/doi.org\/10.5281\/zenodo.10536401\" target=\"_blank\" rel=\"noopener\">https:\/\/doi.org\/10.5281\/zenodo.10536401<\/a>). <b>i<\/b>, To identify in vivo mechanisms recruited by thiorphan treatment, rat brains were removed after 2\u2009weeks of thiorphan infusion and compared with diluent-infused controls. Thiorphan treatment increased immunolabelling for both BDNF and phospho-AKT in the infused motor cortex, reflecting\u00a0a shift to a state that is developmental and pro-regenerative. Scale bars, 20\u2009\u03bcm (<b>c<\/b>,<b>f<\/b>). Scale bars, 25 \u03bcm, inset scale bars, 10\u2009\u03bcm.<\/p>\n<p>Thiorphan was identified as a potential candidate for improving axonal growth after CNS injury by virtue of its ability to shift the cellular transcriptome to an embryonic, pro-growth state. To assess whether this mechanism was actually recruited in neuronal target cells, we performed RNA sequencing (RNA-seq) of macaque M1 motor cortex cells exposed to thiorphan for 5 days in vitro compared with control cultures lacking thiorphan exposure (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig4\" target=\"_blank\" rel=\"noopener\">4g<\/a>). Because we had one sample of thiorphan-treated and one sample of vehicle (dimethylsulfoxide (DMSO))-treated cells, we compared mRNA species changing\u2009\u00b1\u20091.5 log2 units between the two samples: 177 genes reached this cut-off threshold (Supplementary Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"supplementary material anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#MOESM1\" target=\"_blank\" rel=\"noopener\">1c<\/a>). Gene ontology of these 177 genes identified 29 biological processes and remarkably, 16 of these 29 were related to development, including neuron development, nervous system development, and synapse assembly (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig4\" target=\"_blank\" rel=\"noopener\">4h<\/a>). To further examine mechanisms associated with thiorphan delivery, we infused it intracortically for two weeks in rats and performed immunolabelling of the infused region compared with animals that received vehicle infusions: thiorphan administration resulted in increased expression of brain-derived neurotrophic factor (BDNF) (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig4\" target=\"_blank\" rel=\"noopener\">4i<\/a>) and phospho-AKT (Fig. <a data-track=\"click\" data-track-label=\"link\" data-track-action=\"figure anchor\" href=\"http:\/\/www.nature.com\/articles\/s41586-025-09647-y#Fig4\" target=\"_blank\" rel=\"noopener\">4i<\/a>) in the infused region, paralleling higher levels of these molecules observed both in neural development and successful regeneration. These findings support a mechanistic framework in which thiorphan modifies the developmental, metabolic and signalling state of cells to impact neuronal regeneration, consistent with its initial identification on the basis of its ability to replicate the effects of SCI in driving neurons developmentally backward towards a state of embryonic development.<\/p>\n","protected":false},"excerpt":{"rendered":"We adopted a five-step pipeline to identify candidates for enhancing neural repair with a streamlined path that could&hellip;\n","protected":false},"author":3,"featured_media":342722,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[210,10046,10047,61208,159,168836,67,132,68],"class_list":{"0":"post-342721","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-health","8":"tag-health","9":"tag-humanities-and-social-sciences","10":"tag-multidisciplinary","11":"tag-neural-stem-cells","12":"tag-science","13":"tag-spinal-cord-injury","14":"tag-united-states","15":"tag-unitedstates","16":"tag-us"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@us\/115462220981673065","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/342721","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=342721"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/342721\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/342722"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=342721"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=342721"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=342721"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}