Biology subjects

Leal, J.

Publications and source records attributed to Leal, J..

6 recordsLinked to original sources

bioRxiv2025

Perdurant TTC21B protein in the early mouse embryo is required for proper forebrain neural progenitor proliferation.

Primary cilia play a pivotal role in cellular signaling and development and disruptions in ciliary form and/or function leads to human ciliopathies. Here, we examine the role of Ttc21b, a key component of the intraflagellar transport-A complex, in mouse forebrain development using a Ttc21balien null allele. Our findings reveal significant microcephaly in homozygous mutants is caused by disrupted neural progenitor proliferation and differentiation. Histological and immunohistochemical analyses show an enlarged ventricular zone and reduced cortical plate thickness, accompanied by altered mitotic spindle angles, suggesting defects in symmetric versus asymmetric cell divisions. Despite low Ttc21b expression in the forebrain epithelium, early embryonic expression patterns imply that perdurant TTC21B protein may underlie these phenotypes. Progenitor proliferation kinetics were disrupted, with fewer cells re-entering the cell cycle, correlating with reduced TBR2-positive intermediate progenitors and altered neurogenesis dynamics. Neuronal processes in the cortical plate were significantly shortened, suggesting cytoskeletal defects specific to terminal differentiation stages. Our findings support a model where early Ttc21b expression in precursors destined for the forebrain is critical for sustaining later neural progenitor proliferation and differentiation. These results advance our understanding of primary cilia in cortical development and provide a framework for exploring cytoskeletal contributions to ciliopathies.

developmental biology↗

bioRxiv2023

Discovery of peptides for targeted delivery of mRNA lipid nanoparticles to cystic fibrosis lung epithelia

For cystic fibrosis (CF) patients, a lung targeted gene therapy would significantly alleviate pulmonary complications associated with morbidity and mortality. However, mucus in the airways and cell entry pose huge delivery barriers for local gene therapy. Here, we used phage display technology to select for and identify mucus- and cell-penetrating peptides against primary human bronchial epithelial cells (pHBECs) from CF patients cultured at air-liquid interface (ALI). At ALI, pHBECs produce mucus and reflect CF disease pathology, making it a clinically relevant model. Using this model, we discovered a lead candidate peptide, and incorporated it into lipid nanoparticles (LNPs) to deliver mRNA to pHBECs and mouse lungs in vivo. Compared to LNPs without our peptide, peptide-LNPs demonstrated 7.8-fold and 4.8-fold higher mRNA expression in vitro and in vivo, respectively. Since gene delivery to pHBECs is a significant challenge, we are encouraged by these results and anticipate that our peptide could be used to successfully deliver CF gene therapies in future work.

bioengineering↗

bioRxiv2022

Bioelectronic microfluidic wound healing

This work delves into the impact of direct current (DC) stimulation on both healthy and diabetic in vitro wound healing models of keratinocytes, the most prevalent cell type of the skin. The augmentation of non-metal electrode materials and prudent microfluidic design allowed for a platform to study the effects of different sustained (12 hours DC) electric field configurations on wound closure dynamics. We found that electric guidance cues ([~=] 200mVmm-1) enhance wound closure rate by nearly 3X for both healthy and diabetic-like keratinocyte sheets, compared to their respective controls. The motility-inhibited keratinocytes regained wound closure rates with stimulation (increase from 1.0 to 2.8% hr-1) comparable to healthy non-stimulated keratinocyte collectives (3.5% hr-1). Our results bring hope that electrical stimulation is a viable pathway to accelerate wound repair.

bioengineering↗

bioRxiv2019

Identification of peptide coatings that enhance diffusive transport of nanoparticles through the tumor microenvironment

In solid tumors, increasing drug penetration promotes their regression and improves the therapeutic index of compounds. However, the heterogeneous extracellular matrix (ECM) acts a steric and interaction barrier that hinders effective transport of therapeutics, including nanomedicines. Specifically, the interactions between the ECM and surface physicochemical properties of nanomedicines (e.g. charge, hydrophobicity) impedes their diffusion and penetration. To address the challenges using existing surface chemistries, we used peptide-presenting phage libraries as a high-throughput approach to screen and identify peptides as coatings with desired physicochemical properties that improve diffusive transport through the tumor microenvironment. Through iterative screening against the ECM and identification by next-generation DNA sequencing and analysis, we selected individual clones and measured their transport by diffusion assays. Here, we identified a net-neutral charge, hydrophilic peptide P4 that facilitates significantly higher diffusive transport of phage than negative control through in vitro tumor ECM. Through alanine mutagenesis, we confirmed that the hydrophilicity, charge, and their spatial ordering impact diffusive transport. P4 phage clone exhibited almost 200-fold improved uptake in ex vivo pancreatic tumor xenografts compared to the negative control. Nanoparticles coated with P4 exhibited [~]40-fold improvement in diffusivity in pancreatic tumor tissues, and P4-coated particles demonstrated less hindered diffusivity through the ECM compared to particles functionalized with gold standard poly(ethylene) glycol or iRGD peptide ligand. By leveraging the power of molecular diversity using phage display, we can greatly expand the chemical space of surface chemistries that can improve the transport of nanomedicines through the complex tumor microenvironment to ultimately improve their efficacy.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=99 SRC=\"FIGDIR/small/659524v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (23K):\norg.highwire.dtl.DTLVardef@18bc04forg.highwire.dtl.DTLVardef@1feb597org.highwire.dtl.DTLVardef@14403e5org.highwire.dtl.DTLVardef@5bbf6c_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2019

A combinatorial biomolecular strategy to identify peptides for improved transport across the sputum of cystic fibrosis patients and the underlying epithelia

Drugs and drug delivery systems have to traverse multiple biological barriers to achieve therapeutic efficacy. In diseases of mucosal-associated tissues such as cystic fibrosis (CF), successful delivery of gene and drug therapies remains a significant challenge due to an abnormally concentrated viscoelastic mucus, which prevents ~99% of all drugs and particles from penetrating the mucus barrier and the underlying epithelia for effective therapy, resulting in decreased survival. We used combinatorial peptide-presenting phage libraries and next-generation sequencing to identify hydrophilic, close to net-neutral charged peptides that penetrate the mucus barrier ex vivo in sputum from CF patients with ~600-fold better penetration than a positively charged control. After mucus penetration, nanoparticles conjugated with our selected peptides successfully translocated into lung epithelial cells derived from CF patients and demonstrated up to three-fold improved cell uptake compared to non-modified carboxylated- and gold standard PEGylated-nanoparticles. The selected peptides act as surface chemistries with synergistic functions to significantly improve the ability of drug delivery systems to overcome the human mucosal barriers and provide efficient cellular internalization. Our screening strategy provides a biologically-based discovery assay that directly addresses transport through mucus and cell barriers and has the potential to advance drug and gene delivery to multiple mucosal barriers.

bioengineering↗

bioRxiv2019

M13 phage display to identify a permeating peptide against hyperconcentrated mucin

Mucus is an impregnable barrier for drug delivery across the epithelia for treatment of mucosal-associated diseases. While current carriers are promising for mucus penetration, their surface chemistries do not possess chemical complexity to probe and identify optimal physicochemical properties desired for mucus penetration. As initial study, we use M13 phage display presenting random peptides to select peptides that can facilitate permeation through hyperconcentrated mucin. Here, a net-neutral charge, hydrophilic peptide was identified to facilitate transport of phage and fluorophore conjugates through mucin barrier compared to controls. This initial finding warrants further study to understand how composition and spatial distribution of physicochemical properties of peptides can be optimized to improve transport across the mucus barrier.

bioengineering↗