Biology subjects

Fathi, F.

Publications and source records attributed to Fathi, F..

6 recordsLinked to original sources

bioRxiv2026

Time-Resolved Laser Speckle Contrast Imaging (TR-LSCI) of Cerebral Blood Flow Response to Intracranial Pressure Elevation

SignificanceCerebral autoregulation (CA) reflects the dynamic coupling among cerebral blood flow (CBF), intracranial pressure (ICP), and arterial blood pressure (ABP); its failure contributes to secondary brain injury. Existing bedside methods rely on indirect or spatially limited CBF surrogates and cannot resolve microvascular flow dynamics across space, depth, and time. AimTo develop, optimize, and apply a scalable, noncontact time-resolved laser speckle contrast imaging (TR-LSCI) platform for depth-sensitive, high-speed, wide-field CBF imaging during controlled ICP perturbations. ApproachTR-LSCI synchronizes a 20-MHz pulsed laser with a time-gated, single-photon avalanche diode (SPAD) camera (512 x 512 pixels) to detect diffuse photons at varying path lengths, enabling depth-resolved microvascular CBF imaging. Benchtop and mobile TR-LSCI systems were applied in adult rats and a neonatal piglet with synchronized invasive ICP and ABP measurements. ResultsTR-LSCI captured spatially heterogeneous, pulsatile CBF dynamics at up to 52 Hz over large cortical fields of view, with heart rate estimates statistically equivalent to those from ICP and ABP. Multivariable analysis identified reproducible, phase-dependent CA transitions encompassing preserved autoregulation, ABP-driven compensation, and ICP-constrained CBF suppression; notably, CBF alone exhibited distinct phase signatures. ConclusionsTR-LSCI enables dynamic, physiology-informed neurovascular monitoring and supports future bedside CA assessment.

neuroscience↗

bioRxiv2026

A universal platform for simultaneous TCRα/β removal enables safer and more potent TCR therapies and autoimmune modeling

Adoptive T-cell therapies using tumour-specific T-cell receptors (TCRs) are limited by competition with endogenous receptors, which impairs efficacy and poses risks of off-target autoreactivity. Here we present a CRISPR-based platform that completely and selectively eliminates both endogenous TCR- and -{beta} chains without affecting introduced transgenic TCRs, irrespective of codon optimization. This approach achieves >90% deletion efficiency in Jurkat and primary human T cells, markedly enhancing the expression, pairing fidelity, and functional potency of transgenic receptors. Using a clinically relevant HLA-A*02:01-restricted DMF5 TCR, we show that dual TCR ablation boosts antigen-specific activation and cytotoxicity in vitro and significantly enhances tumor clearance in vivo in human immune system (HIS) mice, while preventing graft-versus-host disease (GVHD). Targeted locus amplification revealed that CRISPR-induced double-strand breaks did not alter lentiviral integration profiles, confirming genomic safety. Extending this approach to four insulin-reactive TCRs demonstrated that removal of endogenous receptors increased transduction efficiency and functional activity, with one (1E6) showing selective activation and infiltration of stem cell-derived islet grafts (SC-islets) in vivo. This study establishes a universal, safe, and scalable genome-editing platform for generating functionally precise human T cells. By integrating cancer immunotherapy and autoimmune disease modelling within a single framework, it provides a strong preclinical rationale for dual endogenous TCR removal as a route to improved specificity, safety, and therapeutic efficacy in TCR-based cell therapies.

immunology↗

bioRxiv2025

Coordinated circulating and tissue-based T cell responses precede xenograft rejection

Despite the life-saving successes of solid organ transplantation, the number of individuals needing organ transplant far exceeds the number of organs available for use each year. Porcine xenotransplantation, or the use of pig organs for transplantation in people, holds substantial promise but xenograft rejection in humans is poorly understood. T cell rejection by the host immune system is a major challenge for human allografts and may limit the longevity of porcine xenografts. To study the xenograft rejection, we evaluated T cell responses and repertoire dynamics across tissues following porcine thymokidney transplantation in a decedent model over 61 days after bilateral native kidney nephrectomy. Despite induction with anti-thymocyte globulin and ongoing immune suppression consisting of rituximab, corticosteroids, calcineurin inhibition, and mycophenolate mofetil, human T cell infiltration of the xenograft was observed and was associated with xenograft dysfunction. Longitudinal analysis of T cell clonotypes in biopsies of thymokidney revealed accumulation of clonal human CD4 and CD8 T cell responses. Moreover, circulating activated T cells, including circulating T follicular helper (cTfh), were xeno-reactive and increased in frequency around rejection events. We confirmed clonal dominance of a single CD8 clonotype - identified as donor-reactive in a mixed lymphocyte reaction - in the circulation leading up to the acute cellular rejection event. Following re-treatment with anti-thymocyte globulin and intensification of corticosteroids, the T cell clonotypes were dramatically diminished in frequency in thymokidney and lymph nodes, though not eliminated. Over time of observation, the T cell clonotypes were shared across multiple compartments, including xenograft, circulation and lymph nodes and formed clonal families with known xeno-reactive clonotypes, suggesting a coordinated immune response against a limited pool of antigenic targets. Together, these data demonstrate T cell repertoire dynamics across tissues in the setting of xenograft rejection and highlight opportunities for early surveillance, prediction and potential intervention. One-sentence summaryAfter pig-to-human kidney xenotransplantation, xenoreactive T cells form clonotypic families across blood, graft, and lymphoid tissues, indicating a coordinated and targeted response.

immunology↗

bioRxiv2018

Expression of the miR-302/367 microRNA cluster is regulated by a conserved long non-coding host gene

MicroRNAs (miRNAs) are important regulators of cellular functions. MiR-302/367 is a polycistronic miRNA cluster including miR-302b/c/a/d (collectively termed miR-302s) and miR-367. The cluster is located in the intron of a non-coding host gene. MiR-302s have been shown to repress mRNAs required for differentiation and to induce pluripotency in somatic cells. The stem cell specific transcription factors OCT4, SOX2 and Nanog drive miR-302s expression, however, the reported expression in human and mice indicates a more complex transcriptional regulation. Here we investigate the transcriptional control and the processing of the miR-302 host gene. The murine miR-302 host gene is alternatively spliced, polyadenylated and exported from the nucleus. The regulatory sequences extend at least 2 kb upstream of the transcription start side and contain several conserved binding sites for both transcriptional activators and repressors. Reporter constructs with different upstream regions revealed a significant influence of the more distant regulatory sequences in pluripotent stem cells. The gene structure and regulatory elements like binding sites for activating and repressing transcriptional regulators, splice, and polyadenylation signals are highly conserved between mouse and human. So far, no miR-302 independent function has been annotated for the miR-302 host gene and we hypothesize that the complex and differential regulation of the miRNA transcription and processing might the reason for its conservation. Thus, regulation or micro-RNA expression might be a so far less recognized function of non-coding RNA genes.\n\nAuthor SummaryNon-coding RNAs constitute a large part of the mammalian genome. Interestingly, some long non-coding RNAs (lncRNA) are transcribed and processed in the same way as mRNAs but lack an open reading frame. Here we give evidence that a so far less recognized function of such lncRNAs could be to supply microRNAs with the complex transcriptional control and processing required for their intricate expression. As an example, we analyzed the regulatory sequences of the miR-302/367 host gene. MiR-302/367 is a microRNA cluster involved in the regulation of stem cells and cellular differentiation. We show here that the regulatory region is much more complex than anticipated, a complexity that can not be conferred alone by any of the stem cell specific transcription factors which were so far associated with the expression of miR-302/367.

genetics↗

bioRxiv2018

Transgenic Mice and Pluripotent Stem Cells Express EGFP under the Control of miR-302 Promoter

MicroRNAs are a group of short non-coding RNAs that undertake various roles in different cell signaling pathways and developmental stages. They regulate gene expression levels at the post-transcriptional stage, which results in cleavage of mRNAs or repression of their translation. Some miRNAs, including the miR-302 cluster, are critical regulators for the stemness state of embryonic stem cells and cell fate patterning. The miR-302 cluster is located in the intron of a non-coding gene that has no other reported function, other than hosting miR-302, and grant a complex expression regulation through upstream its regulatory sequences. To date, analysis of the miR-302 expression pattern in a transgenic mouse model has not been reported. In this study, we generated transgenic mice that expressed EGFP driven by miR-302 upstream regulatory sequences that harbored the core promoter of its host gene. We examined the activity of the miR-302 promotor in somatic tissues of transgenic mice, transgenic blastocysts, and embryonic stem cells derived from transgenic blastocysts. Our results showed that miR-302 highly expressed in both blastocysts and the first passages of transgenic embryonic stem cells, and has low expression in the somatic tissues of transgenic mice. It could be concluded that different temporal and spatial gene expression patterns occur during the embryonic and adult stages in mice.

developmental biology↗

bioRxiv2018

Isolation of cancer stem cells by selection for miR-302 expressing cells

Cancer stem cells receive increasing interest because they are believed to be a major reason for long-term therapy failure. The reason for the therapy resistance of cancer stem cells lies partially in their multi-drug resistance and partially in the ability to rest mitotically inactive in the hypoxic center of tumors. Due to their variable number and their often low proliferation rate, cancer stem cells are difficult to purify in decent quantities and to grow in cell culture systems, where they are easily outcompeted by faster growing more differentiated, i.e. less stem cell-like tumor cells. Here we present a proof of principle study based on the idea to select cancer stem cells by means of the expression of a stem cell-specific gene. We inserted a selectable egfp-neo coding sequence in the last exon of the non-coding murine miR-302 host gene. As a stem cell specific regulatory element, we used 2.1 kb of the genomic region immediately upstream of the miR-302 host gene transcription start. Stable transgenic CJ7 embryonic stem cells were used to induce teratomas. After three weeks, tumors were removed for analysis and primary cultures were established. Stem-like cells were selected from these culture based on G418 selection. When the selection was removed, stem cell morphology and miR-302 expression were rapidly lost, indicating that it were not the original ES cells that have been isolated. In conclusion, we show the possibility to use drug resistance expressed from a regulatory sequence of a stem cell-specific marker, to isolate and propagate cancer stem cells that otherwise might be hidden in the majority of tumor cells.

cancer biology↗