All Publications

  • Postpartum Plasma-Derived Exosomes Confer Mitochondrial Stabilization and Neuroprotection against Ischemic Stroke. Research square Sun, X., Xu, L., Greer, M., McMillan, E., Arvola, O., Sultan, P., Ando, K., Min, J. J., Chavda, V., Wolf, J., Mahajan, V., Carvalho, B., Stary, C. M. 2026

    Abstract

    The molecular mechanisms governing adaptive neuroprotection during the postpartum period remain unknown. We hypothesized that circulating exosomes contain bioactive cargo (such as Hsp20) that confer neuroprotection against ischemic injury during the postpartum period.Exosomes were isolated from plasma of postpartum female mice (ppExos) and control female mice, and from serial blood samples obtained from healthy human volunteers during pregnancy (3rd trimester) and again on postpartum day 2. Exosomal size and protein markers were confirmed via nanoparticle tracking analysis and Western blotting. Neuroprotection with exosome treatment was assessed in vitro using mouse neuronal and astrocyte cultures and human retinal pigment cell line subjected to simulated ischemia. In vivo neuroprotection was assessed using transient middle cerebral artery occlusion (MCAO) in young adult and aged mice. Mitochondrial integrity and reactive oxygen species (ROS) production were evaluated by live cell imaging. In vivo neuroprotection was evaluated by assessing infarct volume and neurobehavioral scores. Changes in mitochondrial dynamics were measured by immunofluorescence and Western blot. Human exosomes were sent for proteomic assessment (SomaScan™) followed by differential expression analysis (R software v4). Protein quantification was validated by immunoblot.ppExos significantly reduced infarct volumes and improved neurological deficits post-MCAO in both young and aged female mice. In vitro, ppExos reduced ROS generation in all cell types after simulated ischemia and reduced mitochondrial fragmentation in astrocytes. Mitochondrial fusion proteins Mfn2 and Opa1 proteins were elevated in maternal postpartum brains, and preserved in both astrocyte and neuronal cell cultures after in vitro ischemia with ppExo treatment. Proteomics revealed significant upregulation of heat shock protein 20 (Hsp20) in human ppExos, while Western blot validated elevated Hsp20 in both human and mouse ppExos. Simulated ischemia significantly reduced Hsp20 in astrocyte and neuronal cultures which was reversed by treatment with ppExos. In conclusion, ppExos represent a previously unrecognized, naturally optimized neuroprotective agent that enhances mitochondrial resilience and antioxidant defenses associated with enhanced Hsp20 expression. These findings establish a novel platform for sex-informed, cell-free therapies in ischemic cerebrovascular accidents.

    View details for DOI 10.21203/rs.3.rs-9573067/v1

    View details for PubMedID 42245812

    View details for PubMedCentralID PMC13232446

  • Conditional neuronal deletion of microRNA-141/200c cluster, but not microRNA-181a/b-1 cluster, is protective against experimental stroke in male mice. Physiological reports Xu, L., Griffiths, B., Sun, X., Greer, M., Chang, H., McMillin, E., Manis, E., Russo, I., Dean, C. A., Stary, C. M. 2025; 13 (15): e70505

    Abstract

    MicroRNAs (miRs) regulate the translation of target genes often in a cell-type specific manner. We previously demonstrated that downregulation of either miR-181a or miR-200c with intracranial injection of an inhibitor is protective against experimental stroke in mice. Here, we generated genetic lines of inducible Ca2+-calmodulin kinase IIα (CKIIα) neuronal miR-181a/b-1 and miR-141/200c cluster deletion to investigate whether the protective effect of their inhibition could be neuron-specific. Jackson Lab strains Mirc14tm1.1Czc/J and Mirc13tm1Mtm/Mmjax were each crossed with the tamoxifen-inducible Cre-recombinase strain B6;129S6-Tg, CKIIα-cre/ERT2. Adult double transgenic male mice were randomized and treated with 3 mg tamoxifen or vehicle via oral gavage for 7 days prior to 1 h middle cerebral artery occlusion (MCAO) or sham surgery. Mice were assessed for gross motor function at 24 h and then sacrificed for quantification of infarct volume. Separate animals were assessed for cell-type specific brain expression of miR-181a and miR-200c via combined fluorescent immunohistochemistry and in situ hybridization. Brains from tamoxifen treated mice exhibited selective miR deletion in CKIIα neurons. Infarct volumes were significantly lower, and neurological scores significantly improved in CKIIα/miR-200c mice pretreated with tamoxifen versus vehicle alone. In contrast, no difference was observed in infarct volume or neurological score in CKIIα/miR-181a mice pretreated with tamoxifen versus vehicle.

    View details for DOI 10.14814/phy2.70505

    View details for PubMedID 40810631

  • Medical Misinformation and Quality of Public Video Content on Cannabis for Chronic Pain Management: A Cross-Sectional Analysis of the YouTube Platform. Journal of pain research Etumuse, B., Greer, M., Onyemachi, J., El-Abed, Y., Kamma, S., Shah, J. D., Tran, H. T., Hussain, N., Pittelkow, T. P., D'Souza, R. S. 2024; 17: 3577-3586

    Abstract

    As cannabis legalization expands nationally and globally, its use for chronic pain increases, prompting people to seek information on social media platforms like YouTube. This study evaluates the accuracy and quality of information of popular YouTube videos on cannabis for chronic pain.Using search terms related to cannabis for pain, the top 66 videos by view count were selected. Each video was classified as useful, misleading, or neither. The quality and reliability of each video were assessed using the modified DISCERN, mDISCERN, score and the Global Quality Scale, GQS. The video characteristics, usefulness classification, mDISCERN scores, and GQS scores were summarized. Continuous and categorical outcomes were compared using t-test and chi-square, respectively.Of the 66 videos, 22.73% (n=15) were classified as useful, and 77.27% (n=51) were classified as neither. Of useful videos, 40.00% (n=6) were uploaded by physicians, 40.00% (n=6) were uploaded by corporations, and 6.67% (n=1) were uploaded by an independent user. Of videos classified as neither useful nor misleading, news sources uploaded 27.45% (n=14) of these videos (P=0.02). Physicians uploaded 37.50% (n = 18) of videos with a GQS score ≥3 (P=0.04), while independent users uploaded significantly more videos with a mDISCERN score <3 (22.20%, P=0.02). Useful videos had a mean GQS of 4.00 ± 0.65 compared to a mean GQS of 2.76 ± 0.86 for videos deemed neither (P<0.0001).This study suggests a moderate quality of YouTube content on cannabis use for chronic pain. Given cannabis's growing popularity and potential for misinformation on popular social media platforms, healthcare professionals and organizations should consider uploading educational videos on this topic on YouTube.

    View details for DOI 10.2147/JPR.S479200

    View details for PubMedID 39526076

    View details for PubMedCentralID PMC11550692

  • Misinformation Persists in Complementary Health: Evaluating the Reliability and Quality of YouTube-Based Information on the Use of Acupuncture for Chronic Pain. Journal of pain research Greer, M., Kamma, S., Tran, H., Etumuse, B., Shah, J. D., El-Abed, Y., Onyemachi, J. O., Hussain, N., Pittelkow, T. P., D'Souza, R. S. 2024; 17: 1509-1518

    Abstract

    Acupuncture is commonly used to treat chronic pain. Patients often access public social media platforms for healthcare information when querying acupuncture. Our study aims to appraise the utility, accuracy, and quality of information available on YouTube, a popular social media platform, on acupuncture for chronic pain treatment.Using search terms such as "acupuncture for chronic pain" and "acupuncture pain relief", the top 54 videos by view count were selected. Included videos were >1 minute duration, contained audio in English, had >7000 views, and was related to acupuncture. One primary outcome of interest was categorizing each video's usefulness as useful, misleading, or neither. Another primary outcome of interest was the quality and reliability of each video using validated instruments, including the modified DISCERN (mDISCERN) tool and the Global Quality Scale (GQS). The means were calculated for the video production characteristics, production sources, and mDISCERN and GQS scores. Continuous and categorical outcomes were compared using Student's t-test and chi-square test, respectively.Of the 54 videos, 57.4% were categorized as useful, 14.8% were misleading, and 27.8% were neither. Useful videos had a mean GQS and mDISCERN score of 3.77±0.67 and 3.48±0.63, respectively, while misleading videos had mean GQS and mDISCERN score of 2.50±0.53 and 2.38±0.52, respectively. 41.8% of the useful videos were produced by a healthcare institution while none of the misleading videos were produced by a healthcare institution. However, 87.5% of the misleading videos were produced by health media compared to only 25.8% of useful videos from health media.As patients increasingly depend on platforms like YouTube for trustworthy information on complementary health practices such as acupuncture, our study emphasizes the critical need for more higher-quality videos from unbiased healthcare institutions and physicians to ensure patients are receiving reliable information regarding this topic.

    View details for DOI 10.2147/JPR.S459475

    View details for PubMedID 38646592

    View details for PubMedCentralID PMC11032134

  • Sexual Dimorphism Between Aged Mice in Activity of MicroRNA-181a, Bcl2 and Bcl2 m6A Methylated mRNA After Experimental Stroke Stary, C., Greer, M., Xu, L., Sun, X., Murray, I. LIPPINCOTT WILLIAMS & WILKINS. 2023: 594

    View details for Web of Science ID 001058985600206

  • MicroRNA-494 augments fibrotic transformation of human retinal pigment epithelial cells and targets p27 with cell-type specificity. Frontiers in ophthalmology Leng, T., Kamboj, G., Sun, X., Chang, H., Davda, P., Greer, M., Stary, C. M. 2023; 3: 1168650

    Abstract

    Epiretinal membranes (ERMs) are the result of fibro-cellular proliferation that cause distortion and impairment of central vision. We hypothesized that select microRNAs (miRs) regulate retinal fibro-proliferation and ERM formation. Following IRB approval, a pilot study was performed in patients presenting for retina surgery with and without clinical ERMs. Total RNA was isolated from ERM tissue and controls from non-ERM vitreous and subjected to miR profiling via microarray analysis. MiR-494 was identified as the only miR selectively expressed at significantly greater levels, and in silico analysis identified p27 as a putative fibroproliferative gene target of miR-494. In vitro testing of miR-494 and p27 in fibrotic transformation was assessed in spontaneously immortalized human retinal pigment epithelial (RPE) and human Müller cell lines, stimulated to transform into a fibroproliferative state via transforming growth factor beta (TGFβ). Fibroproliferative transformation was characterized by de novo cellular expression of alpha smooth muscle actin (αSMA). In both RPE and Müller cells, both TGFβ and miR-494 mimic decreased p27 expression. In parallel experiments, transfection with p27 siRNA augmented TGFβ-induced αSMA expression, while only in RPE cells did co-transfection with miR-494 inhibitor decrease αSMA levels. These results demonstrate that miR-494 augments fibrotic transformation in both Müller cells and RPEs, however only in RPEs does miR-494 mediate fibrotic transformation via p27. As p27 is known to regulate cellular proliferation and differentiation, future studies should extend clinical testing of miR-494 and/or p27 as a potential novel non-surgical therapy for ERMs, as well as identify relevant miR-494 targets in Müller cells.

    View details for DOI 10.3389/fopht.2023.1168650

    View details for PubMedID 38983004

    View details for PubMedCentralID PMC11182081

  • Inhibition of microRNA-200c preserves astrocyte sirtuin-1 and mitofusin-2, and protects against hippocampal neurodegeneration following global cerebral ischemia in mice. Frontiers in molecular neuroscience Griffiths, B., Xu, L., Sun, X., Greer, M., Murray, I., Stary, C. 2022; 15: 1014751

    Abstract

    Memory impairment remains a leading disability in survivors of global cerebral ischemia, occurring secondary to delayed neurodegeneration of hippocampal cornu ammonis-1 (CA1) neurons. MicroRNA-200c (miR-200c) is induced following ischemic stress and we have previously demonstrated that pre-treatment with anti-miR-200c is protective against embolic stroke in mice. In the present study we assessed the role of miR-200c on CA1 neurodegeneration, sirtuin-1 (SIRT1), and mitochondrial dynamic protein expression in a mouse model of transient global cerebral ischemia and in vitro in primary mouse astrocyte cultures after simulated ischemia. Mice were subjected to 10 min bilateral common carotid artery occlusion plus hypotension with 5% isoflurane. After 2 h recovery mice were treated with intravenous injection of either anti-miR-200c or mismatch control. Memory function was assessed by Barnes maze at post-injury days 3 and 7. Mice were sacrificed at post-injury day 7 for assessment of brain cell-type specific expression of miR-200c, SIRT1, and the mitochondrial fusion proteins mitofusin-2 (MFN2) and OPA1 via complexed fluorescent in situ hybridization and fluorescent immunohistochemistry. Global cerebral ischemia induced significant loss of CA1 neurons, impaired memory performance and decreased expression of CA1 SIRT1, MFN2, and OPA1. Post-injury treatment with anti-miR-200c significantly improved survival, prevented CA1 neuronal loss, improved post-injury performance in Barnes maze, and was associated with increased post-injury expression of CA1 SIRT1 and MFN2 in astrocytes. In vitro, primary mouse astrocyte cultures pre-treated with miR-200c inhibitor prior to oxygen/glucose deprivation preserved expression of SIRT1 and MFN2, and decreased reactive oxygen species generation, whereas pre-treatment with miR-200c mimic had opposite effects that could be reversed by co-treatment with SIRT1 activator. These results suggest that miR-200c regulates astrocyte mitochondrial homeostasis via targeting SIRT1, and that CA1 astrocyte mitochondria and SIRT1 represent potential post-injury therapeutic targets to preserve cognitive function in survivors of global cerebral ischemia.

    View details for DOI 10.3389/fnmol.2022.1014751

    View details for PubMedID 36466801

    View details for PubMedCentralID PMC9710226