Biology subjects

Morrow, L.

Publications and source records attributed to Morrow, L..

4 recordsLinked to original sources

bioRxiv2025

Microneedle delivery of stem cell derived retinal pigment epithelial cells

Retinal pigment epithelium (RPE) transplantation surgery has shown potential benefits in animal models and early clinical trials. However, current implantation techniques are limited by the need for large retinotomies when cell bearing scaffolds are used or cellular reflux in the case of cell suspension transplantation with micro-cannulae. Here we demonstrate that it is feasible to pass primary and stem cell derived RPE cells through microneedles with a bore as small as 30m. In vitro, there is no immediate loss of cell viability and this remains true throughout 14 days of live cell viability monitoring. Further, when the RPE cells are cultured over 14 days, they attach within 24 hours and become confluent, with normal morphological appearances. The formation of tight junctions is unimpeded with the typical polygonal pattern observed. The effects of shear stress due to passage of the cells through a small lumen were not evident in cultured cells labelled for the cytoskeletal protein F-actin. RPE cell VEGF secretion is unaffected by microneedle size in primary RPE and iPSC RPE cells. Ex vivo surgical implantation demonstrates that the technique is feasible, RPE cells engraft in the outer retina and we show that vitrectomy is not required to successfully transplant cells. Herein, we provide the first evidence of surgical microneedle cell delivery, which may have future applications more broadly within ophthalmic microsurgery and minimally invasive delivery strategies. Graphical summary O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/651158v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@19ca129org.highwire.dtl.DTLVardef@18c3feorg.highwire.dtl.DTLVardef@1eb6300org.highwire.dtl.DTLVardef@b0c946_HPS_FORMAT_FIGEXP M_FIG C_FIG Induced pluripotent stem cells (iPSC) are differentiated into retinal pigment epithelial cells (iPSC RPE) and cultured for 14 days until confluent. A single cell suspension of iPSC RPE is then injected using an Alcon Constellation Vision System machine through different microneedles into a 48 cell culture plate or in the subretinal space of an ex vivo pig eye 3-6 months in age. Cells and tissues were processed and stained by using various antibodies to assess viability, morphology, function and anatomical localization in the subretinal space to confirm the feasibility of microneedle cell delivery.

cell biology↗

bioRxiv2021

Sex- and Subtype-Specific Adaptations in Excitatory Signaling Onto Deep-Layer Prelimbic Cortical Pyramidal Neurons After Chronic Alcohol Exposure

Long-term alcohol use results in behavioral deficits including impaired working memory, elevated anxiety, and blunted inhibitory control that are associated with prefrontal cortical (PFC) dysfunction. Preclinical observations demonstrate multiple impairments in GABAergic neurotransmission onto deep-layer principal cells (PCs) in prelimbic cortex that suggest dependence-related cortical dysfunction is the product of elevated excitability in these cells. Despite accumulating evidence showing alcohol-induced changes in interneuron signaling onto PCs differ between sexes, there is limited data explicitly evaluating sex-specific ethanol effects on excitatory signaling onto deep-layer PCs that may further contribute to deficits in PFC-dependent behaviors. To address this, we conducted electrophysiological and behavioral tests in both male and female Sprague-Dawley rats to evaluate the effects of chronic ethanol exposure. Among our observations, we report a marked enhancement in glutamatergic signaling onto deep-layer PCs in male, but not female, rats after alcohol exposure. This phenomenon was furthermore specific to a sub-class of PC, sub-cortically projecting Type-A cells, and coincided with enhanced anxiety-like behavior, but no observable deficit in working memory. In contrast, female rats displayed an alcohol-induced facilitation in working memory performance with no change in expression of anxiety-like behavior. Together, these results suggest fundamental differences in alcohol effects on cell activity, cortical sub-circuits, and PFC-dependent behaviors across male and female rats.

neuroscience↗

bioRxiv2019

Nutritional Immunity and Antibiotic Drug Treatments Influence Microbial Composition but Fail to Eliminate Urethral Catheter Biofilms in Recurrently Catheterized Patients

Polymicrobial biofilms that form on indwelling urethral catheters used by neurogenic bladder patients are known to recur following catheter replacements. Uropathogens dominate in catheter biofilms (CBs), grow and disperse as multi-cellular aggregates. Their microbial complexity, the characteristics of host immune responses and the molecular crosstalk in this ecosystem are incompletely understood. By surveying eight patients over up to six months with meta-omics analysis methods, we shed new light on the longitudinal microbial dynamics in CBs and the microbial-host crosstalk. There was evidence of chronic innate immune responses in all patients. Pathogens dominated the microbial contents. Proteus mirabilis often out-competed other species in cases of salt encrustation of catheters. The examination of proteomes in CBs and associated urinary pellets revealed many abundant bacterial systems for transition metal ion (TMI) acquisition. TMIs are sequestered by effector proteins released by activated neutrophils and urothelial cells, such as lactotransferrin and calgranulins, which were abundant in the host proteomes. We identified positive quantitative correlations among systems responsible for siderophore biosynthesis, TMI/siderophore uptake and TMI cellular import in bacterial species, suggesting competition for TMIs to support their metabolism and growth in CBs. Enterococcus faecalis was prevalent as a cohabitant of CBs and expressed three lipoproteins with apparent TMI acquisition functions. Fastidious anaerobic bacteria such as Veillonella, Actinobaculum, and Bifidobacterium grew in CB communities that appeared to be oxygen starved. Finally, antibiotic drug treatments were shown to influence microbial composition of CBs but failed to prevent re-colonization of urethral catheters with persisting and/or drug-resistant newly emerging pathogens.

microbiology↗

bioRxiv2018

Longitudinal Surveys Show that Urethral Catheters Harbor Recurrent Polymicrobial Biofilms with Cooperative and Competitive Behaviors Among Cohabitating Pathogens

The analysis of catheter biofilms (CBs) from patients with neurogenic bladder disorders revealed persistent colonization by polymicrobial communities. The recurrence of bacterial species in the CBs of sequentially replaced catheters suggests urothelial reservoirs responsible for recolonization of the catheter surface. Proteomic data for CB samples were indicative of chronic inflammation in the patients urinary tracts via neutrophil and eosinophil infiltration and epithelial cell exfoliation. These host defense pathways, effective in killing pathogens during uncomplicated urinary tract infection, failed to eliminate CBs. Intermittent antibiotic drug treatment had different outcomes: either replacement of drug-susceptible by drug-tolerant bacteria or transient microbial biomass reduction followed by resurgence of the previously colonizing bacteria. Proteins that sequester iron and zinc such as lactotransferrin, lipocalin-2 and calprotectin were abundant in the patients CBs and urine sediments. Indicative of a host-pathogen battle for bivalent metal ions, acquisition and transport systems for such ions were highly expressed by many organisms residing in CBs. Species part of the Enterococcaceae and Aerococcaceae families, generally not well-characterized in their ability to synthesize siderophores, frequently cohabitated biofilms dominated by siderophore-producing Enterobacteriaceae. In support of metal acquisition cooperativity, we noticed positive abundance correlations for a Proteus mirabilis yersiniabactin-type siderophore system and two Enterococcus faecalis ABC transporters. Distinct bacterial strains highly expressed known or putative cytotoxins that appeared to compromise the survival of co-resident bacteria, e.g. a P. mirabilis hemolysin and Pseudomonas aeruginosa type 6 secretion and pyoverdin biosynthesis systems. In conclusion, there is support for cooperative and competitive behaviors among bacteria cohabitating CBs.

microbiology↗