Browsing by Author "Seo, Joon Pyung"

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    Acoustically targeted measurement of transgene expression in the brain
    (AAAS, 2024) Seo, Joon Pyung; Trippett, James S.; Huang, Zhimin; Lee, Sangsin; Nouraein, Shirin; Wang, Ryan Z.; Szablowski, Jerzy O.; Bioengineering; Systems, Synthetic, and Physical Biology; Rice Applied Physics Graduate Program; Rice Neuroengineering Initiative
    Gene expression is a critical component of brain physiology, but monitoring this expression in the living brain represents a major challenge. Here, we introduce a new paradigm called recovery of markers through insonation (REMIS) for noninvasive measurement of gene expression in the brain with cell type, spatial, and temporal specificity. Our approach relies on engineered protein markers that are produced in neurons but exit into the brain’s interstitium. When ultrasound is applied to targeted brain regions, it opens the blood-brain barrier and releases these markers into the bloodstream. Once in blood, the markers can be readily detected using biochemical techniques. REMIS can noninvasively confirm gene delivery and measure endogenous signaling in specific brain sites through a simple insonation and a subsequent blood test. REMIS is reliable and demonstrated consistent improvement in recovery of markers from the brain into the blood. Overall, this work establishes a noninvasive, spatially specific method of monitoring gene delivery and endogenous signaling in the brain.
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    Acoustically targeted measurement of transgene expression in the brain
    (2025-04-25) Seo, Joon Pyung; Szablowski, Jerzy
    Gene expression is a critical component of brain physiology and activity. Brain development, function, and plasticity relies on a regulated process of converting genetic information into functional products. However, monitoring gene expression in the living brain has been a significant challenge. The confined structure of the brain, protected by the cranium and shielded by the blood-brain barrier, has posed difficulty in non-invasive and sensitive measurement of gene expression with specificity. The aim of this thesis is to develop a new paradigm of technology capable of measuring gene expression in the brain non-invasively with cell-type, spatial, and temporal specificity. To achieve this, we combined focused ultrasound liquid biopsy and recovery of engineered protein markers that are designed to be expressed in neurons and exit into the brain’s interstitium. When ultrasound is applied to targeted brain regions, it temporarily opens the blood-brain barrier and releases the interstitial markers into the bloodstream. Once in blood, the markers can be readily detected from blood collection followed by compatible biochemical techniques. We call this Recovery of Markers through InSonation (REMIS). We demonstrated improved recovery of engineered Gaussia luciferase marker, under constitutive promoter, from the brain into the blood in every tested animal. Further, we implemented the markers to measure endogenous neuronal signaling activity by controlling the expression of the marker under a genetic circuit that responds to c-Fos when activated by enhanced neuronal activity. Lastly, we measured enhanced serum level of overexpressed human alpha-synuclein in the engineered Parkinson’s disease model mThy1-aSyn (Line61) mouse strain with REMIS. Overall, our work demonstrates the feasibility of combining engineered gene expression reporters and focused ultrasound liquid biopsy to noninvasively and specifically measure gene expression in the intact brain.
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    Recovery of Markers through Insonation: An alternative to monitoring gene expression in deep tissues
    (2023-02-13) Seo, Joon Pyung; Szablowski, Jerzy
    We developed a method to noninvasively measure transgene expression in the specific brain regions using a blood test. To achieve this, we used engineered protein reporters that are released from the cells into the brain interstitium. We then used focused ultrasound (FUS) to transiently open the blood-brain barrier (BBBO) and release these reporters into the blood. We call this approach REcovery of Markers through InSonation, or REMIS. We show that levels of markers secreted from neurons into the serum correlate with the levels of transgene expression in the brain. We measured up to 5.5-fold increase of marker levels in the blood after opening of 8% of the blood-brain barrier (BBB). We show the procedure is well tolerated and avoids significant tissue damage, consistent with other BBB opening studies. Finally, we show that the marker is released from the brain over prolonged periods of time. The levels of the released marker were comparable at 7.5 minutes and 2 hours after FUS-BBBO (p=0.31, paired t-test). At the same time, the serum half-life of the marker injected intravenously was 7.6 minutes. This suggests that the marker was released from the brain gradually, replenishing the marker in the serum over 2 hours, and indicating a broad time window available for marker collection. Monitoring gene expression in deep tissues of living animals is critical for in vivo studies and translation of gene therapies. This technology allows for site-specific measurement of gene expression in the brain.