Biology subjects

Saberi, A.

Publications and source records attributed to Saberi, A..

22 records · Page 2Linked to original sources

bioRxiv2022

Wireless closed-loop smart bandage for chronic wound management and accelerated tissue regeneration

Chronic non-healing wounds represent a major source of morbidity for patients and a significant economic burden. Current wound care treatments are generally passive and are unable to adapt to changes in the wound environment in real time. By integrating multimodal sensors and adding stimulators in a bandage, real-time physiological monitoring is possible and provides an opportunity for active intervention into the complex wound environment. Here, we develop a battery-free flexible bioelectronic system consisting of wirelessly powered, closed-loop sensing and stimulation circuits with tissue-interfacing tough conducting hydrogel electrodes for robust signal transduction, on-demand adhesion, and detachment. Using multiple pre-clinical models, we demonstrate the capability of our wound care system to continuously monitor skin impedance and temperature, to trigger directional electrical stimulation. The accelerated wound closure was confirmed to be due to the activation of pro-regenerative genes linked to accelerated wound closure, increased neovascularization, and enhanced dermal recovery.

bioengineering↗

bioRxiv2020

Human cerebral tissues created via active cellular reaggregation produce functionally interconnected 3D neuronal network to mimic pathological circuit disturbance

Various characteristics of a developing central nervous system, including sensory input-output1,2, neuronal migration3,4, and regionalization3,5, have been recapitulated through recent advances in the culture of brain organoids. These organoids can model the fundamental processes in brain development and disease. A remaining critical challenge, however, is to achieve complex neuronal networks with functional interconnectivity as in native brain tissue. Generation of current organoid models originates from classic dissociation-reaggregation paradigms6, often relying on mechanically-enforced quick reaggregation of pluripotent stem cells7. Here we describe an alternative method that promotes matrix-supported active (migrative) reaggregation of cells (MARC), reminiscent of in vivo developmental morphing processes, to engineer multi-regional brain tissues in vitro. Measurements of neuronal activity in intact 3D tissues revealed functional interconnectivity, characteristic of cerebral neuronal networks. As a proof of concept, we show that interconnected cerebral tissues produced using this approach can mimic propagation of epileptiform discharges in a custom-built in-vitro platform.

bioengineering↗

bioRxiv2018

A planarian nidovirus expands the limits of RNA genome size

RNA viruses are the only known RNA-protein (RNP) entities capable of autonomous replication (albeit within a permissive environment). A 33.5-kb nidovirus has been considered close to the upper size limit for such entities; conversely, the minimal cellular DNA genome is ~200 kb. This large difference presents a daunting gap for the transition from primordial RNP to contemporary DNA-RNP-based life. Whether or not RNA viruses represent transitional steps on the road to DNA-based life, studies of larger RNA viruses advance our understanding of size constraints on RNP entities. For example, emergence of the largest previously known RNA genomes (20-34 kb in positive-stranded nidoviruses, including coronaviruses) is associated with a proofreading exoribonuclease encoded in the nidoviral open reading frame 1b (ORF1b). However, apparent constraints on the size of ORF1b, which encodes this and other key replicative enzymes, have been hypothesized to limit further expansion of viral RNA genomes. Here, we characterize a novel nidovirus (planarian secretory cell nidovirus; PSCNV) whose disproportionately large ORF1b-like region, and overall 41.1 kb genome, substantially extend the presumed limits on RNA genome size. This genome encodes a predicted 13,556-aa polyprotein in an unconventional single ORF, yet retains canonical nidoviral genome organization and expression, and key replicative domains. Our evolutionary analysis suggests that PSCNV diverged early from multi-ORF nidoviruses, and subsequently acquired additional genes, including those typical of large DNA viruses or hosts. PSCNVs greatly expanded genome, proteomic complexity, and unique features - impressive in themselves - attest to the likelihood of still-larger RNA genomes awaiting discovery.\n\nSignificance StatementRNA viruses are the only known RNA-protein (RNP) entities capable of autonomous replication. The upper genome size for such entities was assumed to be <35 kb; conversely, the minimal cellular DNA genome is ~200 kb. This large difference presents a daunting gap for the proposed evolution of contemporary DNA-RNP-based life from primordial RNP entities. Here, we describe a nidovirus from planarians, whose 41.1 kb genome is 23% larger than the largest known of RNA virus. The planarian secretory cell nidovirus has broken apparent constraints on the size of the genomic subregion that encodes core replication machinery, and has acquired genes not previously observed in RNA viruses. This virus challenges and advances our understanding of the limits to RNA genome size.

microbiology↗

bioRxiv2018

Complete guide RNA design for CRISPR-mediated regulation of human long noncoding RNA transcription

Transcription inhibition and activation of long noncoding RNAs (lncRNAs) mediated by clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 technology provides potential advantages in high-throughput functional genomics studies over RNA interference or overexpression platforms. In this work, we identify over 90,000 lncRNA transcription start sites (TSSs) based on the MiTranscriptome human genome annotation and design single guide RNA (sgRNA) libraries with strong predicted activities and low off-target effects for CRISPR-mediated inhibition and activation (CRISPRi/a) of their transcription. A large fraction of these TSSs correspond to putative genes that are not annotated in common reference genome annotations and have never been functionally studied. Our CRISPRi/a libraries, or their context-dependent subsets, are potentially useful in genome-scale functional studies of human lncRNAs.

bioengineering↗