Xenotransplantation of human adipose-derived stem cells in zebrafish embryos

Fabrication of Adipose-Derived Stem Cell-Based Self-Assembled Scaffold under Hypoxia and Mechanical Stimulation for Urethral Tissue Engineering

Long urethral strictures are often treated with autologous genital skin and buccal mucosa grafts; however, risk of hair ingrowth and donor site morbidity, restrict their application. To overcome this, we introduced a tissue-engineered human urethra comprising adipose-derived stem cell (ASC)-based self-assembled scaffold, human urothelial cells (UCs) and smooth muscle cells (SMCs). ASCs were cultured with ascorbic acid to stimulate extracellular matrix (ECM) production. The scaffold (ECM) was stained with collagen type-I antibody and the thickness was measured under a confocal microscope. Results showed that the thickest scaffold (28.06 ± 0.59 μm) was achieved with 3 × 10⁴ cells/cm² seeding density, 100 μg/mL ascorbic acid concentration under hypoxic and dynamic culture condition. The biocompatibility assessment showed that UCs and SMCs seeded on the scaffold could proliferate and maintain the expression of their markers (CK7, CK20, UPIa, and UPII) and (α-SMA, MHC and Smootheline), respectively, after 14 days of in vitro culture. ECM gene expression analysis showed that the ASC and dermal fibroblast-based scaffolds (control) were comparable. The ASC-based scaffold can be handled and removed from the plate. This suggests that multiple layers of scaffold can be stacked to form the urothelium (seeded with UCs), submucosal layer (ASCs only), and smooth muscle layer (seeded with SMCs) and has the potential to be developed into a fully functional human urethra for urethral reconstructive surgeries.

Xenotransplantation of adult hippocampal neural progenitors into the developing zebrafish for assessment of stem cell plasticity

Adult stem cells are considered multipotent, restricted to differentiate into a few tissue-specific cell types. With the advent of technologies which can dedifferentiate and transdifferentiate cell types, assumptions about the process of cell fate determination must be reconsidered, including the role of extrinsic versus intrinsic factors. To determine the plasticity of adult neural progenitors, rat hippocampal progenitor cells were xenotransplanted into embryonic zebrafish. These animals allow for easy detection of transplanted cells due to their external development and transparency at early stages. Adult neural progenitors were observed throughout the zebrafish for the duration of the experiment (at least five days post-transplantation). While the majority of transplanted cells were observed in the central nervous system, a large percentage of cells were located in superficial tissues. However, approximately one-third of these cells retained neural morphology and expression of the neuronal marker, Class III β-tubulin, indicating that the transplanted adult neural progenitors did not adapt alternate fates. A very small subset of cells demonstrated unique, non-neural flattened morphology, suggesting that adult neural progenitors may exhibit plasticity in this model, though at a very low rate. These findings demonstrate that the developing zebrafish may be an efficient model to explore plasticity of a variety of adult stem cell types and the role of external factors on cell fate.

The Power of Zebrafish in Personalised Medicine

The goal of personalised medicine is to develop tailor-made therapies for patients in whom currently available therapeutics fail. This approach requires correlating individual patient genotype data to specific disease phenotype data and using these stratified data sets to identify bespoke therapeutics. Applications for personalised medicine include common complex diseases which may have multiple targets, as well as rare monogenic disorders, for which the target may be unknown. In both cases, whole genome sequence analysis (WGS) is discovering large numbers of disease associated mutations in new candidate genes and potential modifier genes. Currently, the main limiting factor is the determination of which mutated genes are important for disease progression and therefore represent potential targets for drug discovery. Zebrafish have gained popularity as a model organism for understanding developmental processes, disease mechanisms and more recently for drug discovery and toxicity testing. In this chapter, we will examine the diverse roles that zebrafish can make in the expanding field of personalised medicine, from generating humanised disease models to xenograft screening of different cancer cell lines, through to finding new drugs via in vivo phenotypic screens. We will discuss the tools available for zebrafish research and recent advances in techniques, highlighting the advantages and potential of using zebrafish for high throughput disease modeling and precision drug discovery.

Tissue Inhibitor of Matrix Metalloproteinases-1 Knockdown Suppresses the Proliferation of Human Adipose-Derived Stem Cells

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a multifunctional matrix metalloproteinase, and it is involved in the regulation of cell proliferation and apoptosis in various cell types. However, little is known about the effect of TIMP-1 expression on the proliferation of adipose-derived stem cells (ADSCs). Therefore, TIMP-1 expression in the ADSCs was firstly detected by western blotting, and TIMP-1 gene was knocked down by lentivirus-mediated shRNA. Cell proliferation was then evaluated by MTT assay and Ki67 staining, respectively. Cell cycle progression was determined by flow cytometry. The changes of p51, p21, cyclin E, cyclin-dependent kinase 2 (CDK2), and P-CDK2 caused by TIMP-1 knockdown were detected by western blotting. The results indicated that ADSCs highly expressed TIMP-1 protein, and the knockdown of TIMP-1 inhibited cell proliferation and arrested cell cycle progression at G₁ phase in the ADSCs possibly through the upregulation of p53, p21, and P-CDK2 protein levels and concurrent downregulation of cyclin E and CDK2 protein levels. These findings suggest that TIMP-1 works as a positive regulator of cell proliferation in ADSCs.