Generation of a Transgenic Zebrafish Model for Pancreatic Beta Cell Regeneration

Generation of Zebrafish Models of Human Retinitis Pigmentosa Diseases Using CRISPR/Cas9-Mediated Gene Editing System

Generating animal models can explore the role of new candidate genes in causing diseases and the pathogenicity of a specific mutation in the underlying genes. These animals can be used to identify new pharmaceutical or genetic therapeutic methods. In the present experiment, we developed a rpe65a knock out (KO) zebrafish as a retinitis pigmentosa (RP) disease model. Using the CRISPR/Cas9 system, the rpe65a gene was KO in zebrafish. Two specific single-guide RNAs (sgRNAs) were designed for the zebrafish rpe65a gene. SgRNAs were cloned into the DR274 plasmid and synthesized using in vitro transcription method. The efficiency of Ribonucleoprotein (synthesized sgRNA and recombinant Cas9) was evaluated by in vitro digestion experiment. Ribonucleoprotein complexes were microinjected into one to four-celled eggs of the TU zebrafish strain. The effectiveness of sgRNAs in KO the target gene was determined using the Heteroduplex mobility assay (HMA) and Sanger sequencing. Online software was used to determine the percent of mosaicism in the sequenced samples. By examining the sequences of the larvae that showed a mobility shift in the HMA method, the presence of indels in the binding region of sgRNAs was confirmed, so the zebrafish model for RP disease established. Zebrafish is an ideal animal model for the functional study of various diseases involving different genes and mutations and used for evaluating different therapeutic approaches in human diseases. This study presents the production of rpe65a gene KO zebrafish models using CRISPR/Cas9 technology. This model can be used in RP pathophysiology studies and preclinical gene therapy experiments.

Investigation of Kelussia Odoratissima and Angelica Sinensis Similarities in Zebrafish-based In-vivo Bioactivity Assays and Their Chemical Composition

BACKGROUND

Kelussia odoratissima and Angelica sinensis are two medicinal plants commonly used in Iran and China, respectively. They have been used in their indigenous traditional medicine, for various diseases including, blood refining, inflammation, cold, flu, stress, cardiovascular diseases, and nervous disorders. This study was conducted to evaluate the volatile oil composition of K. odoratissima leaves (KVL) and A. sinensis root (AVR); we also examined the biological activity of essential oils (EOs) and hydroalcoholic extracts of both plants using two different transgenic zebrafish (Danio rerio) models: angiogenesis and pancreatic beta cell (pBC) regeneration models.

MATERIALS AND METHODS

Both EOs were isolated by hydrodistillation and analysed by GC and GC/MS. For viability tests, larvae were treated with different concentrations of extracts to determine an appropriate starting concentration. Hydroalcoholic extracts and EOs have been tested in a dose-dependent manner for their biological activity using tissue-specific transgenic zebrafish Tg(fli-1: EGFP) and Tg (ins: GFP-NTR) embryos and larvae. One-way ANOVA was used to compare the mean of pBC area and intersegmental vessels (ISVs) outgrowth between the treatment groups.

RESULTS

Eleven compounds were in common to both oils, comprising 51.3% of KVL and 61.7% of AVR, of which 39.3% in KVL and 37.6% in AVR were phthalide structures. Results revealed that both EOs blocked ISVs formation in the Tg (fli-1: EGFP) embryos increased to 10% of the control value, while both hydroalcoholic extracts did not show any anti-angiogenesis effects in these embryos. In addition, AVR has been shown to significantly induce PBC regeneration following ablation in the Tg (ins: GFP-NTR), but its regenerative activity was lower than that of 5'-N-ethylcarboxamidoadenosine (NECA) as a positive control. Taken together, the anti-angiogenesis activity of both EOs could be attributed to the phthalide structures while for the PBC regenerative activity, other compounds including β-Thujaplicinol, exclusively existing in AVR, might be effective.

CONCLUSION

Although the genera, organs, and origin of these plants are different, their similar chemical composition and biological activities make them valuable resources for further investigation in basic medical and pharmaceutical science.

Non-Invasive Monitoring of Cutaneous Wound Healing in Non-Diabetic and Diabetic Model of Adult Zebrafish Using OCT Angiography

A diabetic wound presents a severe risk of infections and other complications because of its slow healing. Evaluating the pathophysiology during wound healing is imperative for wound care, necessitating a proper diabetic wound model and assay for monitoring. The adult zebrafish is a rapid and robust model for studying human cutaneous wound healing because of its fecundity and high similarities to human wound repair. OCTA as an assay can provide three-dimensional (3D) imaging of the tissue structure and vasculature in the epidermis, enabling monitoring of the pathophysiologic alterations in the zebrafish skin wound. We present a longitudinal study for assessing the cutaneous wound healing of the diabetic adult zebrafish model using OCTA, which is of importance for the diabetes research using the alternative animal models. We used non-diabetic (n = 9) and type 1 diabetes mellitus (DM) adult zebrafish models (n = 9). The full-thickness wound was generated on the fish skin, and the wound healing was monitored with OCTA for 15 days. The OCTA results demonstrated significant differences between diabetic and non-diabetic wound healing, involving delayed tissue remodeling and impaired angiogenesis for the diabetic wound, leading to slow wound recovery. The adult zebrafish model and OCTA technique may benefit long-term metabolic disease studies using zebrafish for drug development.

Research Progress on the Construction and Application of a Diabetic Zebrafish Model

Diabetes is a metabolic disease characterized by high blood glucose levels. With economic development and lifestyle changes, the prevalence of diabetes is increasing yearly. Thus, it has become an increasingly serious public health problem in countries around the world. The etiology of diabetes is complex, and its pathogenic mechanisms are not completely clear. The use of diabetic animal models is helpful in the study of the pathogenesis of diabetes and the development of drugs. The emerging vertebrate model of zebrafish has many advantages, such as its small size, large number of eggs, short growth cycle, simple cultivation of adult fish, and effective improvement of experimental efficiency. Thus, this model is highly suitable for research as an animal model of diabetes. This review not only summarizes the advantages of zebrafish as a diabetes model, but also summarizes the construction methods and challenges of zebrafish models of type 1 diabetes, type 2 diabetes, and diabetes complications. This study provides valuable reference information for further study of the pathological mechanisms of diabetes and the research and development of new related therapeutic drugs.

Establishment of a Drug Screening Model for Cardiac Complications of Acute Renal Failure

Acute renal failure (ARF) is a clinical critical syndrome with rapid and severe decline of renal function. Complications of ARF, especially its cardiac complications (cardiorenal syndrome type 3, CRS-3), are the main causes of death in patients with ARF. However, the shortage and limited efficacy of therapeutic drugs make it significant to establish new large-scale drug screening models. Based on the Nitroreductase/Metronidazole (NTR/MTZ) cell ablation system, we constructed a Tg(cdh17:Dendra2-NTR) transgenic zebrafish line, which can specifically ablate renal tubular epithelial cells. The absence of renal tubular epithelial cells can lead to ARF in zebrafish larvae. The ARF symptoms, such as heart enlargement, slow heart rate and blood stasis, are similar to the clinical manifestations of human CRS-3. Furthermore, two therapeutic drugs (digoxin and enalapril) commonly used in the clinical treatment of heart failure were also effective in alleviating the symptoms of CRS-3 in zebrafish, which proved the effectiveness of this model. Drug screening further discovered a potential drug candidate, α-lipoic acid, which can effectively alleviate the symptoms of CRS-3 through its antioxidant function. Accordingly, we established a new ARF model of zebrafish, which laid a foundation for large-scale screening of new therapeutic drugs for its complications.

Which Hyperglycemic Model of Zebrafish (Danio rerio) Suites My Type 2 Diabetes Mellitus Research? A Scoring System for Available Methods

Despite extensive studies on type 2 diabetes mellitus (T2DM), there is no definitive cure, drug, or prevention. Therefore, for developing new therapeutics, proper study models of T2DM is necessary to conduct further preclinical researches. Diabetes has been induced in animals using chemical, genetic, hormonal, antibody, viral, and surgical methods or a combination of them. Beside different approaches of diabetes induction, different animal species have been suggested. Although more than 85% of articles have proposed rat (genus Rattus) as the proper model for diabetes induction, zebrafish (Danio rerio) models of diabetes are being used more frequently in diabetes related studies. In this systematic review, we compare different aspects of available methods of inducing hyperglycemia referred as T2DM in zebrafish by utilizing a scoring system. Evaluating 26 approved models of T2DM in zebrafish, this scoring system may help researchers to compare different T2DM zebrafish models and select the best one regarding their own research theme. Eventually, glyoxalase1 (glo1-/-) knockout model of hyperglycemia achieved the highest score. In addition to assessment of hyperglycemic induction methods in zebrafish, eight most commonly proposed diabetic induction approval methods are suggested to help researchers confirm their subsequent proposed models.