Biology subjects

Stoppel, W. L.

Publications and source records attributed to Stoppel, W. L..

5 recordsLinked to original sources

bioRxiv2025

Regionalization of gene expression and cell types in the silk gland of the pantry moth Plodia interpunctella

Lepidopteran silk glands include a posterior silk gland (PSG) that secretes core fibers and a middle silk gland (MSG) that secretes adhesive sericins. While well-studied in the silkworm (Bombyx mori), little is known about the gene expression profiles underlying the diversity of lepidopteran silks. Here we characterized the silk gland from the pantry moth Plodia interpunctella using a combination of quantitative and spatial assays. RNA-seq analyses of differential gene expression between the MSG and PSG depict the transcriptomic divergence between these two secretory tissues. In the PSG, high expression of fibroin genes FibL and FibH were detected, whereas MSG samples were dominated by transcripts encoding major sericins-- bioadhesive proteins that form the coating of the silk fiber. Hybridization Chain Reaction (HCR) mRNA profiling revealed sharp cellular boundaries within the silk gland: PSG cells exclusively expressed fibroins, while MSG comprised two compartments each expressing different combinations of sericins. Our findings corroborate the conserved organization of lepidopteran silk glands into specialized secretory subdivisions, and establish Plodia as a promising comparative model for studying silk diversity. This work provides a foundation for future research into the cellular and evolutionary basis of silk production across Lepidoptera.

genomics↗

bioRxiv2023

Silk Fibroin Particles as Carriers in the Development of All-Natural Hemoglobin-Based Oxygen Carriers (HBOCs)

Oxygen therapeutics have a range of applications in transfusion medicine and disease treatment. Synthetic molecules and all-natural or semi-synthetic hemoglobin-based oxygen carriers (HBOCs) have seen success as potential circulating oxygen carriers. However, many early HBOC products were removed from the market due to side effects from excess hemoglobin in the blood stream and hemoglobin entering the tissue. To overcome these issues, research has focused on increasing the molecular diameter of hemoglobin by polymerizing hemoglobin molecules or encapsulating hemoglobin in liposomal carriers, where immune responses and circulation times remain a challenge. This work looks to leverage the properties of silk fibroin, a cytocompatible and non-thrombogenic biopolymer, known to entrap protein-based cargo, to engineer a silk fibroin-hemoglobin-based oxygen carrier (sfHBOC). Herein, an all-aqueous solvent evaporation technique was used to form silk fibroin particles with and without hemoglobin to tailor the formulation for specific particle sizes. The encapsulation efficiency and ferrous state of hemoglobin were analyzed, resulting in 60% encapsulation efficiency and a maximum of 20% ferric hemoglobin, yielding 100 {micro}g/mL active hemoglobin in certain sfHBOC formulations. The system did not elicit a strong inflammation response in vitro, demonstrating the potential for this particle system to serve as an injectable HBOC. Table of Contents Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/530637v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@75421aorg.highwire.dtl.DTLVardef@46c895org.highwire.dtl.DTLVardef@11ac0ceorg.highwire.dtl.DTLVardef@1682663_HPS_FORMAT_FIGEXP M_FIG C_FIG Table of Contents Figure: In this manuscript, we generate silk fibroin particles using an all-aqueous processing technique starting from silk fibroin polymer systems of differing molecular weights. We analyze the extent to which silk concentration and extraction time affect particle size. Further, we analyze the encapsulation of hemoglobin in the particle system and assess immune activation in macrophage-like cultures.

bioengineering↗

bioRxiv2022

Impact of bioactive molecule inclusion in lyophilized silk scaffolds varies between in vivo and in vitro assessments

Biomaterials can influence the coordinated efforts required to achieve tissue rehabilitation. Sponge-like silk fibroin scaffolds that include bioactive molecules have been shown to influence tissue repair. However, the mechanisms by which scaffold formulations elicit desired in vivo responses is unclear. Here, acellular silk scaffolds consisting of type I collagen, heparin, and/or vascular endothelial growth factor (VEGF) were used to investigate material fabrication and composition parameters that drive scaffold degradation, cell infiltration, and adipose tissue deposition in vivo. In subcutaneous implants, scaffold degradation was assessed, and results show that the percentage of cells infiltrating the scaffold increased when scaffold formulations contained bioactive molecules. To gain further insight, calculated in vitro enzymatic degradation rates increased with higher enzyme concentrations and theoretical cleavage sites. However, the addition of type I collagen and heparin to the scaffold at relevant concentrations did not change degradation rates, compared to silk alone. These in vitro results are contrary to observations in vivo, where bioactive molecules influence local protein deposition, immune cell infiltration rates, and vascularization. Thus, quantitative in vitro and in vivo evaluations aid in determining the mechanisms by which biomaterials influence tissue repair and support intentional biomaterial design for clinical applications. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=157 SRC="FIGDIR/small/493207v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@7b403forg.highwire.dtl.DTLVardef@1b6ed79org.highwire.dtl.DTLVardef@a0b439org.highwire.dtl.DTLVardef@9843f3_HPS_FORMAT_FIGEXP M_FIG C_FIG This work examines the role of scaffold fabrication and bioactive molecule inclusion on the enzymatic degradation of silk fibroin-based lyophilized sponges. Specifically, the roles of collagen I, heparin, and vascular endothelial growth factor are analyzed to determine the impact of formulation on rate of degradation. In addition, scaffolds are either pre-fabricated, where these bioactive molecules are included in the polymer solution prior to casting the scaffold or the bioactive molecules are introduced following scaffold formation through passive adsorption to the silk fibroin scaffold surface. Scaffolds are enzymatically degraded in vitro, and kinetic rate constants are calculated for the different formulations. In vivo, cellularity, adipose tissue accumulation, and scaffold area are assessed over time. Additionally, immunohistochemistry is used to visualize VEGF Receptor 2, CD 68, and -smooth muscle actin over time.

bioengineering↗

bioRxiv2021

Jointly Optimized Spatial Histogram UNET Architecture (JOSHUA) for Adipose Tissue Segmentation

ObjectiveWe quantify adipose tissue deposition at surgical sites as a function of biomaterial implantation. Impact StatementTo our knowledge, this study is the first investigation to apply convolutional neural network (CNN) models to identify and segment adipose tissue in histological images from silk fibroin biomaterial implants. IntroductionWhen designing biomaterials for the treatment of various soft tissue injuries and diseases, one must consider the extent of adipose tissue deposition. In this work, we implant silk fibroin biomaterials in a rodent subcutaneous injury model. Current strategies for quantifying adipose tissue after biomaterial implantation are often tedious and prone to human bias during analysis. MethodsWe used CNN models with novel spatial histogram layer(s) that can more accurately identify and segment regions of adipose tissue in hematoxylin and eosin (H&E) and Massons Trichrome stained images, allowing for determination of the optimal biomaterial formulation. We compared the method, Jointly Optimized Spatial Histogram UNET Architecture (JOSHUA), to the baseline UNET model and an extension of the baseline model, Attention UNET, as well as to versions of the models with a supplemental "attention"-inspired mechanism (JOSHUA+ and UNET+). ResultsThe inclusion of histogram layer(s) in our models shows improved performance through qualitative and quantitative evaluation. ConclusionOur results demonstrate that the proposed methods, JOSHUA and JOSHUA+, are highly beneficial for adipose tissue identification and localization. The new histological dataset and code for our experiments are publicly available.

bioengineering↗

bioRxiv2020

Extracellular matrix and cyclic stretch alter fetal cardiomyocyte proliferation and maturation in a rodent model of heart hypoplasia

Birth defects, particularly those that affect development of the heart, are a leading cause of morbidity and mortality in infants and young children. Babies born with heart hypoplasia (HH) disorders often have a poor prognosis. It remains unclear whether cardiomyocytes from hypoplastic hearts retain the potential to recover growth, although this knowledge would be beneficial for developing therapies for HH disorders. The objective of this study was to determine the proliferation and maturation potential of cardiomyocytes from hypoplastic hearts and whether these behaviors are influenced by biophysical signaling from the extracellular matrix (ECM) and cyclic mechanical stretch. Congenital diaphragmatic hernia (CDH)-associated HH was induced in rat fetuses by maternal exposure to nitrofen. Hearts were isolated from embryonic day 21 nitrofen-treated fetuses positive for CDH (CDH+) and from fetuses without nitrofen administration during gestation. CDH+ hearts were smaller and had decreased myocardial proliferation, along with evidence of decreased maturity compared to healthy hearts. In culture, CDH+ cardiomyocytes remained immature and demonstrated increased proliferative capacity compared to their healthy counterparts. Culture on ECM derived from CDH+ hearts led to a significant reduction in proliferation for both CDH+ and healthy cardiomyocytes. Healthy cardiomyocytes were dosed with exogenous nitrofen to examine whether nitrofen may have an abhorrent effect on the proliferative ability of cardiomyocyte, yet no significant change in proliferation was observed. When subjected to stretch, CDH+ cardiomyocytes underwent lengthening of sarcomeres while healthy cardiomyocyte sarcomeres were unaffected. Taken together, our results suggest that alterations to environmental cues such as ECM and stretch may be important factors in the pathological progression of HH.

cell biology↗