A gene edited pig model for studying LGR5+ stem cells: implications for future applications in tissue regeneration and biomedical research.

Recent advancements in genome editing techniques, notably CRISPR-Cas9 and TALENs, have marked a transformative era in biomedical research, significantly enhancing our understanding of disease mechanisms and helping develop novel therapies. These technologies have been instrumental in creating precise animal models for use in stem cell research and regenerative medicine. For instance, we have developed a transgenic pig model to enable the investigation of LGR5-expressing cells. The model was designed to induce the expression of H2B-GFP under the regulatory control of the LGR5 promoter via CRISPR/Cas9-mediated gene knock-in. Notably, advancements in stem cell research have identified distinct subpopulations of LGR5-expressing cells within adult human, mouse, and pig tissues. LGR5, a leucine-rich repeat-containing G protein-coupled receptor, enhances WNT signaling and these LGR5+ subpopulations demonstrate varied roles and anatomical distributions, underscoring the necessity for suitable translational models. This transgenic pig model facilitates the tracking of LGR5-expressing cells and has provided valuable insights into the roles of these cells across different tissues and species. For instance, in pulmonary tissue, Lgr5+ cells in mice are predominantly located in alveolar compartments, driving alveolar differentiation of epithelial progenitors via Wnt pathway activation. In contrast, in pigs and humans, these cells are situated in a unique sub-basal position adjacent to the airway epithelium. In fetal stages a pattern of LGR5 expression during lung bud tip formation is evident in humans and pigs but is lacking in mice. Species differences with respect to LGR5 expression have also been observed in the skin, intestines, and cochlea further reinforcing the need for careful selection of appropriate translational animal models. This paper discusses the potential utility of the LGR5+ pig model in exploring the role of LGR5+ cells in tissue development and regeneration with the goal of translating these findings into human and animal clinical applications.

Efficacious cellular therapy of descemetocele in a dog.

The cornea is comprised of 4 layers; the outermost layer is the epithelium, followed by the stroma, Descemet's membrane, and endothelium. Corneal descemetocele is a serious consequence of progressive corneal ulceration, characterized by a herniation of the Descemet membrane through an overlying stromal defect. It requires urgent intervention due to the risk of perforation. Although there are several treatments available for this type of corneal ulcer, conservative approaches may be inadequate due to the typical severity of this injury. Surgical interventions, including conjunctival autograft transplantation and corneoscleral transposition, are commonly used. Mesenchymal stem cells (MSCs) have been used to effectively treat corneal ulcers, but there are limited reports regarding its use for descemetocele. A 7-year-old female shih tzu was diagnosed with descemetocele. In this dog, 2 × 106 MSCs, provided by CellTech - Stem Cell Technologies, were injected bilaterally into the conjunctiva, with an additional 5 × 105 MSCs applied topically to each eye. The ulcer achieved complete remission with an absence of corneal opacity after 75 d, supporting the claim that MSCs are an effective and safe option for the treatment of descemetocele. Key clinical message: The dog's descemetocele healed completely after a single application of MSCs after 30 d, with scars and leukoma completely absent after 75 d. No surgical intervention was required.

Thérapie cellulaire efficace de la descemétocèle chez un chien. La cornée est composée de quatre couches; la couche la plus externe est l'épithélium, suivi du stroma, de la membrane de Descemet et de l'endothélium. La descémétocèle cornéenne est une conséquence grave de l'ulcération cornéenne progressive, caractérisée par une hernie de la membrane de Descemet à travers un défaut stromal sus-jacent. Elle nécessite une intervention urgente en raison du risque de perforation. Bien qu'il existe plusieurs traitements disponibles pour ce type d'ulcère cornéen, les approches conservatrices peuvent être inadéquates en raison de la gravité typique de cette blessure. Les interventions chirurgicales, y compris une autogreffe conjonctivale et la transposition cornéosclérale, sont couramment utilisées. Les cellules souches mésenchymateuses (MSCs) ont été utilisées pour traiter efficacement les ulcères cornéens, mais il existe peu de rapports concernant leur utilisation pour la descemétocèle. Une femelle shih tzu de 7 ans a été diagnostiquée avec descemetocele. Chez ce chien, 2 × 106 MSCs, fournies par CellTech ­ Stem Cell Technologies, ont été injectées bilatéralement dans la conjonctive, avec 5 × 105 MSCs supplémentaires appliquées localement sur chaque oeil. L'ulcère a obtenu une rémission complète avec une absence d'opacité cornéenne après 75 jours, soutenant l'affirmation selon laquelle les MSCs sont une option efficace et sûre pour le traitement de la descemétocèle.Message clinique clé:La descemétocèle de ce chien a complètement guéri après une seule application de MSCs après 30 jours, avec des cicatrices et un leucome complètement absents après 75 jours. Aucune intervention chirurgicale n'a été nécessaire.(Traduit par Dr Serge Messier).

Dysregulated Gene Expression of Imprinted and X-Linked Genes: A Link to Poor Development of Bovine Haploid Androgenetic Embryos.

Mammalian uniparental embryos are efficient models for genome imprinting research and allow studies on the contribution of the paternal and maternal genomes to early embryonic development. In this study, we analyzed different methods for production of bovine haploid androgenetic embryos (hAE) to elucidate the causes behind their poor developmental potential. Results indicate that hAE can be efficiently generated by using intracytoplasmic sperm injection and oocyte enucleation at telophase II. Although androgenetic haploidy does not disturb early development up to around the 8-cell stage, androgenetic development is disturbed after the time of zygote genome activation and hAE that reach the morula stage are less capable to reach the blastocyst stage of development. Karyotypic comparisons to parthenogenetic- and ICSI-derived embryos excluded chromosomal segregation errors as causes of the developmental constraints of hAE. However, analysis of gene expression indicated abnormal levels of transcripts for key long non-coding RNAs involved in X chromosome inactivation and genomic imprinting of the KCNQ1 locus, suggesting an association with X chromosome and some imprinted loci. Moreover, transcript levels of methyltransferase 3B were significantly downregulated, suggesting potential anomalies in hAE establishing de novo methylation. Finally, the methylation status of imprinted control regions for XIST and KCNQ1OT1 genes remained hypomethylated in hAE at the morula and blastocyst stages, confirming their origin from spermatozoa. Thus, our results exclude micromanipulation and chromosomal abnormalities as major factors disturbing the normal development of bovine haploid androgenotes. In addition, although the cause of the arrest remains unclear, we have shown that the inefficient development of haploid androgenetic bovine embryos to develop to the blastocyst stage is associated with abnormal expression of key factors involved in X chromosome activity and genomic imprinting.

Derivation and Differentiation of Canine Ovarian Mesenchymal Stem Cells.

Interest in mesenchymal stem cells (MSCs) has increased over the past decade due to their ease of isolation, expansion, and culture. Recently, studies have demonstrated the wide differentiation capacity that these cells possess. The ovary represents a promising candidate for cell-based therapies due to the fact that it is rich in MSCs and that it is frequently discarded after ovariectomy surgeries as biological waste. This article describes procedures for the isolation, expansion, and differentiation of MSCs derived from the canine ovary, without the necessity of cell-sorting techniques. This protocol represents an important tool for regenerative medicine because of the broad applicability of these highly differentiable cells in clinical trials and therapeutic uses.