Biology subjects

Wilson, R. L.

Publications and source records attributed to Wilson, R. L..

5 recordsLinked to original sources

bioRxiv2023

Intervertebral Disc Elastography to Relate Shear Modulus and Relaxometry in Compression and Bending

Intervertebral disc degeneration is the most recognized cause of low back pain, characterized by the decline of tissue structure and mechanics. Image-based mechanical parameters (e.g., strain, stiffness) may provide an ideal assessment of disc function that is lost with degeneration but unfortunately remains underdeveloped. Moreover, it is unknown whether strain or stiffness of the disc may be predicted by MRI relaxometry (e.g. T1 or T2), an increasingly accepted quantitative measure of disc structure. In this study, we quantified T1 and T2 relaxation times and in-plane strains using displacement-encoded MRI within the disc under physiological levels of compression and bending. We then estimated shear modulus in orthogonal image planes and compared these values to relaxation times and strains within regions of the disc. Intratissue strain depended on the loading mode, and shear modulus in the nucleus pulposus was typically an order of magnitude lower than the annulus fibrosis, except in bending, where the apparent stiffness depended on the loading. Relative shear moduli estimated from strain data derived under compression generally did not correspond with those from bending experiments, with no correlations in the sagittal plane and only 4 of 15 regions correlated in the coronal plane, suggesting that future inverse models should incorporate multiple loading conditions. Strain imaging and strain-based estimation of material properties may serve as imaging biomarkers to distinguish healthy and diseased discs. Additionally, image-based elastography and relaxometry may be viewed as complementary measures of disc structure and function to assess degeneration in longitudinal studies.

bioengineering↗

bioRxiv2023

Maternal, placental and fetal response to a non-viral, polymetric nanoparticle gene therapy in nonhuman primates

BackgroundCurrently, there are no placenta-targeted treatments to alter the in utero environment. Water-soluble polymers have a distinguished record of clinical relevance outside of pregnancy. We have demonstrated the effective delivery of polymer-based nanoparticles containing a non-viral human insulin-like 1 growth factor (IGF1) transgene to correct placental insufficiency in small animal models of fetal growth restriction (FGR). Our goal was to extend these studies to the pregnant nonhuman primate (NHP) and assess maternal, placental and fetal responses to nanoparticle-mediated IGF1 treatment. MethodsPregnant macaques underwent ultrasound-guided intraplacental injections of nanoparticles (GFP- or IGF1-expressing plasmid under the control of the trophoblast-specific PLAC1 promoter complexed with a HPMA-DMEAMA co-polymer) at approximately gestational day 100 (term = 165 days). Fetectomy was performed 24 h (GFP; n =1), 48 h (IGF1; n = 3) or 10 days (IGF1; n = 3) after nanoparticle delivery. Routine pathological assessment was performed on biopsied maternal tissues, and placental and fetal tissues. Maternal blood was analyzed for complete blood count (CBC), immunomodulatory proteins and growth factors, progesterone (P4) and estradiol (E2). Placental ERK/AKT/mTOR signaling was assessed using western blot and qPCR. FindingsFluorescent microscopy and in situ hybridization confirmed placental uptake and transgene expression in villous syncytiotrophoblast. No off-target expression was observed in maternal and fetal tissues. Histopathological assessment of the placenta recorded observations not necessarily related to the IGF1 nanoparticle treatment. In maternal blood, CBCs, P4 and E2 remained within the normal range for pregnant macaques across the treatment period. Changes to placental ERK and AKT signaling at 48 h and 10 d after IGF1 nanoparticle treatment indicated an upregulation in placental homeostatic mechanisms to prevent over activity in the normal pregnancy environment. InterpretationMaternal toxicity profile analysis and lack of adverse reaction to nanoparticle-mediated IGF1 treatment, combined with changes in placental signaling to maintain homeostasis indicates no deleterious impact of treatment. FundingNational Institutes of Health, and Wisconsin National Primate Research Center.

physiology↗

bioRxiv2020

Insulin-like growth factor 1 signaling in the placenta requires endothelial nitric oxide synthase to support trophoblast function and normal fetal growth

Currently, there is no effective treatment for placenta dysfunction in utero. In a ligated mouse model of fetal growth restriction (FGR), nanoparticle-mediated human insulin-like 1 growth factor (hIGF1) gene delivery (NP-Plac1-hIGF1) increased hIGF1 expression and maintained fetal growth. However, whether it can restore fetal growth remains to be determined. Using the endothelial nitric oxide synthase knockout (eNOS-/-) mouse model, a genetic model of FGR, we found that despite inducing expression of hIGF1 in the placentas treated with NP-Plac1-hIGF1 (P=0.0425), FGR did not resolve. This was associated with no change to the number of fetal capillaries in the placenta labyrinth; an outcome increased with NP-Plac1-hIGF1 treatment in the ligated mouse model, despite increased expression of angiopoietin 1 (P=0.05) and suggested IGF1 signaling in the placenta requires eNOS to modulate placenta angiogenesis. To further assess this hypothesis, we used the BeWo Choriocarcinoma cell line and human placenta explant cultures that were treated with NP-Plac1-hIGF1, oxidative stress was induced with hydrogen peroxide (H2O2) and NOS activity inhibited using the inhibitor L-NMMA. In both BeWo and explants, the protective effect of NP-Plac1-hIGF1 treatment against H2O2 induced cell death/lactate dehydrogenase release was prevented by eNOS inhibition (P=0.003 and P<0.0001, respectively). This was associated with an increase in mRNA expression of oxidative stress markers HIF1 (P<0.0001) and ADAM10 (P=0.0002) in the NP-Plac1-hIGF1+H2O2+L-NMMA treated BeWo cells. These findings show for the first time the requirement of eNOS/NOS in IGF1 signaling in placenta cells that may have implications for placental angiogenesis and fetal growth.

physiology↗

bioRxiv2020

Placental and fetal characteristics of the Ohia mouse line recapitulate outcomes in human hypoplastic left heart syndrome

Congenital heart defects (CHDs) are the most common birth defect worldwide. The morbidity and mortality associated with these defects is compounded by increased frequency of fetal growth abnormalities. In the Ohia mouse model of hypoplastic left heart syndrome (HLHS), the double homozygous genotype is embryonically lethal at mid-pregnancy; a time in which optimal establishment of the placenta is crucial to fetal survival. We aimed to characterize placental and fetal growth and development in the double heterozygous genotype (Sap130m/+Pcdha9m/+) to determine whether the genetic mutations associated with HLHS in the Ohia mouse also affect the placenta. The frequency of fetuses with reduced weight near term was shifted in the Sap130m/+Pcdha9m/+ fetuses compared to wildtype. This shift in fetal weight distribution in the Sap130m/+Pcdha9m/+ fetuses was associated with reduced labyrinth region area (P<0.001) and reduced fetal capillary density (P<0.001) in the placentas. Positive correlations were observed between fetal weight and placenta mRNA expression of several nutrient transporters in the Sap130m/+Pcdha9m/+ fetuses but not observed in the wildtype. Increased protein expression of Slc7a5 (P<0.05) and Slc7a8 (P<0.05) was also found in the placenta of Sap130m/+Pcdha9m/+ fetuses. This data shows, despite a potential compensatory mechanism to increase nutrient transport, abhorrent placental vascularization leads to inadequate fetal growth in the Ohia mouse model. Such differences are similar to findings in studies of human placentas and highlights the importance of this mouse model in continuing to understand the developmental links and disruptions to the heart-placenta axis.

physiology↗

bioRxiv2019

A novel human enteroid-anaerobe co-culture system to study microbial-host interaction under physiological hypoxia

Mechanistic investigations of host-microbe interactions in the human gut are limited by current co-culture model systems. The intestinal epithelium requires oxygen for viability, while gut bacteria are facultative or obligate anaerobes. The ability to model host-commensal interactions under dynamic oxygen conditions is critical to understanding host-pathogen interactions in the human gut. Here, we demonstrate a simple, cost-effective method for co-culturing obligate anaerobic bacteria with human intestinal enteroid monolayers under variable oxygen conditions. The Enteroid-Anaerobe Co-Culture (EACC) system is able to recapitulate the steep oxygen gradient seen in vivo and induce expression of hypoxia-associated phenotypes such as increased barrier integrity and expression of antimicrobial peptide genes. Using clinical strains of the commensal anaerobes Bacteroides thetaiotaomicron and Blautia sp. on established patient-derived intestinal enteroid cell lines under physiological hypoxia, the EACC system can sustain host-anaerobe interactions for at least 24 hours. Following co-culture with anaerobic bacteria, we demonstrate patient-specific differences in epithelial response, reinforcing the potential to develop a personalized medicine approach to bacteriotherapy and host-microbe interaction investigations. Our innovative EACC system provides a robust model for investigating host-microbe interactions in complex, patient-derived intestinal tissues, that facilitates study of mechanisms underlying the role of the microbiome in health and disease.

bioengineering↗