Rabbit model of retinoblastoma

Histone Deacetylases in Retinoblastoma

Retinoblastoma, a pediatric ocular malignancy, presents significant challenges in comprehending its molecular underpinnings and targeted therapeutic approaches. The dysregulated activity of histone deacetylases (HDACs) has been associated with retinoblastoma pathogenesis, influencing critical cellular processes like cell cycle regulation or retinal ganglion cell apoptosis. Through their deacetylase activity, HDACs exert control over key tumor suppressors and oncogenes, influencing the delicate equilibrium between proliferation and cell death. Furthermore, the interplay between HDACs and the retinoblastoma protein pathway, a pivotal aspect of retinoblastoma etiology, reveals a complex network of interactions influencing the tumor microenvironment. The examination of HDAC inhibitors, encompassing both established and novel compounds, offers insights into potential approaches to restore acetylation balance and impede retinoblastoma progression. Moreover, the identification of specific HDAC isoforms exhibiting varying expression in retinoblastoma provides avenues for personalized therapeutic strategies, allowing for interventions tailored to individual patient profiles. This review focuses on the intricate interrelationship between HDACs and retinoblastoma, shedding light on epigenetic mechanisms that control tumor development and progression. The exploration of HDAC-targeted therapies underscores the potential for innovative treatment modalities in the pursuit of more efficacious and personalized management strategies for this disease.

Review: New horizons in retinoblastoma treatment: an updated review article

Retinoblastoma (Rb) is a rare childhood intraocular malignancy with an incidence rate of approximately 9000 children per year worldwide. The management of Rb is inherently complex and depends on several factors. The orders of priorities in the treatment of Rb are saving life, globe salvage and vision salvage. Rarity and the young age at diagnosis impede conducting randomized clinical trials (RCTs) for new therapeutic options, and therefore pre-RCTs studies are needed. This review provides an overview of advances in Rb treatment options, focusing on the emergence of new small molecules to treat Rb. Articles related to the management and treatments of Rb were searched in different databases. Several studies and animal models discussing recent advances in the treatment of Rb were included to have a better grasp of the biological mechanisms of Rb. Over the years, the principles of management and treatment of Rb have changed significantly. Innovations in targeted therapies and molecular biology have led to improved patient and ocular survival. However, there is still a need for further evaluation of the long-term effects of these new treatments.

AN IN VIVO STUDY OF INTRAVITREAL RANIBIZUMAB FOLLOWING SUBRETINAL INOCULATION OF RB CELLS IN RABBITS EYES

AIM

This study aimed to determine the effects of a single intravitreal ranibizumab injection in rabbits induced with retinoblastoma (RB).

MATERIAL AND METHODS

RB was induced in six New Zealand white rabbits by subretinal injection of a cultured WERI-RBb-1 cell line into the right eye. After six weeks, Group A (n = 3) was given intravitreal ranibizumab injection (0.3mg in 0.03ml) and Group B (n = 3) was the control. Baseline and serial clinical examinations were performed on days 1, 3, 6, 12, 15, 18 and 21. The right eyes were enucleated for both groups on day 21 for histopathological examination.

RESULTS

The rabbits in both groups developed intraocular lesions which was detectable clinically at one-week post-tumor inoculation. The tumor grew slowly without spontaneous regression. After the animals in Group A were given an intravitreal ranibizumab injection, regression of the tumor was detected clinically, while the tumor in Group B continued to grow slowly. Histopathological findings confirmed the presence of a tumor that closely resembled features of poorly differentiated human RB cells. At the end of 21 days, the size of the tumor was larger in Group B in comparison to Group A. However, the treated group also developed a focal area of retinal hyperplasia. There was no significant side effect of ranibizumab injection except temporary high intraocular pressure immediately post-injection, which was relieved after paracentesis.

CONCLUSIONS

Intravitreal ranibizumab is a potential treatment for RB. It is an effective therapy with a tolerable safety profile in this animal experimental study.

Intravitreal HDAC Inhibitor Belinostat Effectively Eradicates Vitreous Seeds Without Retinal Toxicity In Vivo in a Rabbit Retinoblastoma Model

Purpose

Current melphalan-based regimens for intravitreal chemotherapy for retinoblastoma vitreous seeds are effective but toxic to the retina. Thus, alternative agents are needed. Based on the known biology of histone deacetylases (HDACs) in the retinoblastoma pathway, we systematically studied whether the HDAC inhibitor belinostat is a viable, molecularly targeted alternative agent for intravitreal delivery that might provide comparable efficacy, without toxicity.

Methods

In vivo pharmacokinetic experiments in rabbits and in vitro cytotoxicity experiments were performed to determine the 90% inhibitory concentration (IC₉₀). Functional toxicity by electroretinography and structural toxicity by optical coherence tomography (OCT), OCT angiography, and histopathology were evaluated in rabbits following three injections of belinostat 350 µg (2× IC₉₀) or 700 µg (4× IC₉₀), compared with melphalan 12.5 µg (rabbit equivalent of the human dose). The relative efficacy of intravitreal belinostat versus melphalan to treat WERI-Rb1 human cell xenografts in rabbit eyes was directly quantified. RNA sequencing was used to assess belinostat-induced changes in RB cell gene expression.

Results

The maximum nontoxic dose of belinostat was 350 µg, which caused no reductions in electroretinography parameters, retinal microvascular loss on OCT angiography, or retinal degeneration. Melphalan caused severe retinal structural and functional toxicity. Belinostat 350 µg (equivalent to 700 µg in the larger human eye) was equally effective at eradicating vitreous seeds in the rabbit xenograft model compared with melphalan (95.5% reduction for belinostat, P < 0.001; 89.4% reduction for melphalan, P < 0.001; belinostat vs. melphalan, P = 0.10). Even 700 µg belinostat (equivalent to 1400 µg in humans) caused only minimal toxicity. Widespread changes in gene expression resulted.

Conclusions

Molecularly targeted inhibition of HDACs with intravitreal belinostat was equally effective as standard-of-care melphalan but without retinal toxicity. Belinostat may therefore be an attractive agent to pursue clinically for intravitreal treatment of retinoblastoma.

Evaluation of osteochondral-like tissues using human freeze-dried cancellous bone and chondrocyte sheets to treat osteochondral defects in rabbits

Human freeze-dried cancellous bone combined with human chondrocyte sheets have recently been used to construct an osteochondral-like tissue, which resembled a cartilage layer on a subchondral bone layer. Nevertheless, the efficacy of these human tissues in a xenogeneic model has been rarely reported. Therefore, this study aimed to evaluate the potential of human freeze-dried cancellous bones combined with human chondrocyte sheets for the treatment of osteochondral defects in rabbits. The key roles of the extracellular matrix (ECM) and released cytokines in these tissues in osteochondral repair were also assessed. Triple-layered chondrocyte sheets were constructed using a temperature-responsive culture surface. Then, they were placed onto cancellous bone to form chondrocyte sheet-cancellous bone tissues. The immunostaining of collagen type II (COL2) and the proteomic analysis of the human tissues were carried out before the transplantation. In our in vitro study, the triple-layered chondrocyte sheets adhered well on the cancellous bone, and the COL2 expression was apparent throughout the tissue structures. From the proteomic analysis results, it was found that the major function of the secreted proteins found in these tissues was protein binding. The distinct pathways were focal adhesion and the ECM-receptor interaction pathways. Among the highly expressed proteins, laminin-alpha 5 (LAMA5) and fibronectin (FN) not only played roles in the protein binding and ECM-receptor interaction, but also were involved in the cytokine-mediated signaling pathway. At 12 weeks after xenogeneic transplantation, compared to the control group, the defects treated with the chondrocyte sheets showed more hyaline-like cartilage tissue, as indicated by the abundance of safranin-O and COL2 with a partial collagen type I (COL1) expression. At 4, 8, and 12 weeks, compared to the defects treated with the cancellous bone, the staining of safranin-O and COL2 was more apparent in the defects treated with the chondrocyte sheet-cancellous bone tissues. Therefore, the human chondrocyte sheets and chondrocyte sheet-cancellous bone tissues provide a potential treatment for rabbit femoral condyle defect. LAMA5 and FN found in these human xenografts and their culture media might play key roles in the ECM-receptor interaction and might be involved in the cytokine-mediated signaling pathway during tissue repair.

Complete preclinical platform for intravitreal chemotherapy drug discovery for retinoblastoma: Assessment of pharmacokinetics, toxicity and efficacy using a rabbit model

Current melphalan-based intravitreal chemotherapy regimens for retinoblastoma vitreous seeds are effective, but cause significant ocular toxicity. We describe protocols for each step of a drug discovery pipeline for preclinical development of novel drugs to maximize efficacy and minimize toxicity. These protocols include: 1) determination of vitreous pharmacokinetics in vivo, 2) in vitro assessment of drug cytotoxicity against retinoblastoma based on empiric pharmacokinetics, 3) back-calculation of minimum injection dose to achieve therapeutic concentrations, 4) in vivo determination of maximum-tolerable intravitreal dose, using a multimodal, structural and functional toxicity-assessment platform, and 5) in vivo determination of drug efficacy using a rabbit orthotopic xenograft model of retinoblastoma vitreous seeds. We likewise describe our methodology for direct quantitation of vitreous seeds, and the statistical methodology for assessment of toxicity and efficacy in evaluating novel drugs, as well as for comparisons between drugs.•Multi-step pipeline for intravitreal chemotherapy drug discovery for retinoblastoma, using novel rabbit models.•Detailed protocols for determination of vitreous pharmacokinetics, calculation of optimal dose to inject to achieve therapeutic vitreous levels, determination of maximum tolerable dose using a novel complete toxicity-assessment platform, and in vivo efficacy against retinoblastoma using methodology to directly quantify vitreous tumor burden.•Associated statistical methodology is also presented.

Increasing the efficiency of the retinoblastoma brachytherapy protocol with ultrasonic hyperthermia and gold nanoparticles: a rabbit model

PURPOSE

This study purposed to evaluate the efficacy of brachytherapy with the modality of ultrasonic hyperthermia in the presence of gold nanoparticles (GNPs) on an ocular retinoblastoma tumor in an animal model of the rabbit.

MATERIALS AND METHODS

A retinoblastoma tumor was induced by the injection of the human cell line of Y79 in rabbit eyes (n = 41). After two weeks, tumor size reached a diameter of about 5-7 mm. Seven groups were involved: control, GNPs injection, hyperthermia, hyperthermia with GNPs injection, brachytherapy with I-125, a combination of hyperthermia and brachytherapy, and a combination of brachytherapy, hyperthermia and, GNPs. The tumor area was measured using B-mode ultrasound images on the zero-day and at the end of the third week. The groups were evaluated for a histopathological study of tumor necrosis.

RESULTS

There was a significant difference between the relative area changes of tumor in the combination group with the other study groups (p < .05). The results of histopathologic studies confirmed the necrosis of living retinoblastoma cells.

CONCLUSION

Combination therapy of brachytherapy and hyperthermia with GNPs reduces the relative size of the tumor. This method increases the necrosis percentage of retinoblastoma and significantly reduces the retinoblastoma mass in the rabbit eyes.

Generation of genetically-engineered animals using engineered endonucleases

The key to successful drug discovery and development is to find the most suitable animal model of human diseases for the preclinical studies. The recent emergence of engineered endonucleases is allowing for efficient and precise genome editing, which can be used to develop potentially useful animal models for human diseases. In particular, zinc finger nucleases, transcription activator-like effector nucleases, and the clustered regularly interspaced short palindromic repeat systems are revolutionizing the generation of diverse genetically-engineered experimental animals including mice, rats, rabbits, dogs, pigs, and even non-human primates that are commonly used for preclinical studies of the drug discovery. Here, we describe recent advances in engineered endonucleases and their application in various laboratory animals. We also discuss the importance of genome editing in animal models for more closely mimicking human diseases.

Pharmacokinetics, Tissue Localization, Toxicity, and Treatment Efficacy in the First Small Animal (Rabbit) Model of Intra-Arterial Chemotherapy for Retinoblastoma

Purpose

Current intra-arterial chemotherapy (IAC) drug regimens for retinoblastoma have ocular and vascular toxicities. No small-animal model of IAC exists to test drug efficacy and toxicity in vivo for IAC drug discovery. The purpose of this study was to develop a small-animal model of IAC and to analyze the ocular tissue penetration, distribution, pharmacokinetics, and treatment efficacy.

Methods

Following selective ophthalmic artery (OA) catheterization, melphalan (0.4 to 1.2 mg/kg) was injected. For pharmacokinetic studies, rabbits were euthanized at 0.5, 1, 2, 4, or 6 hours following intra-OA infusion. Drug levels were determined in vitreous, retina, and blood by liquid chromatography tandem mass spectrometry. To assess toxicity, angiograms, photography, fluorescein angiography, and histopathology were performed. For in situ tissue drug distribution, matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) was performed. The tumor model was created by combined subretinal/intravitreal injection of human WERI-Rb1 retinoblastoma cells; the tumor was treated in vivo with intra-arterial melphalan or saline; and induction of tumor death was measured by cleaved caspase-3 activity.

Results

OA was selectively catheterized for 79 of 79 (100%) eyes in 47 of 47 (100%) rabbits, and melphalan was delivered successfully in 31 of 31 (100%) eyes, without evidence of vascular occlusion or retinal damage. For treated eyes, maximum concentration (Cmax) in the retina was 4.95 μM and area under the curve (AUC0→∞) was 5.26 μM·h. Treated eye vitreous Cmax was 2.24 μM and AUC0→∞ was 4.19 μM·h. Vitreous Cmax for the treated eye was >100-fold higher than for the untreated eye (P = 0.01), and AUC0→∞ was ∼50-fold higher (P = 0.01). Histology-directed MALDI-IMS revealed highest drug localization within the retina. Peripheral blood Cmax was 1.04 μM and AUC0→∞ was 2.07 μM·h. Combined subretinal/intravitreal injection of human retinoblastoma cells led to intra-retinal tumors and subretinal/vitreous seeds, which could be effectively killed in vivo with intra-arterial melphalan.

Conclusions

This first small-animal model of IAC has excellent vitreous and retinal tissue drug penetration, achieving levels sufficient to kill human retinoblastoma cells, facilitating future IAC drug discovery.

The wide utility of rabbits as models of human diseases

Studies using the European rabbit Oryctolagus cuniculus contributed to elucidating numerous fundamental aspects of antibody structure and diversification mechanisms and continue to be valuable for the development and testing of therapeutic humanized polyclonal and monoclonal antibodies. Additionally, during the last two decades, the use of the European rabbit as an animal model has been increasingly extended to many human diseases. This review documents the continuing wide utility of the rabbit as a reliable disease model for development of therapeutics and vaccines and studies of the cellular and molecular mechanisms underlying many human diseases. Examples include syphilis, tuberculosis, HIV-AIDS, acute hepatic failure and diseases caused by noroviruses, ocular herpes, and papillomaviruses. The use of rabbits for vaccine development studies, which began with Louis Pasteur’s rabies vaccine in 1881, continues today with targets that include the potentially blinding HSV-1 virus infection and HIV-AIDS. Additionally, two highly fatal viral diseases, rabbit hemorrhagic disease and myxomatosis, affect the European rabbit and provide unique models to understand co-evolution between a vertebrate host and viral pathogens.

Rabbits offer a powerful complement to rodents as a model for studying human immunology, disease pathology, and responses to infectious disease. A review from Pedro Esteves at the University of Porto, Portugal, Rose Mage of the National Institute of Allergy and Infectious Disease, Bethesda, USA and colleagues highlights some of the areas of research where rabbits offer an edge over rats and mice. Rabbits have a particularly sophisticated adaptive immune system, which could provide useful insights into human biology and produce valuable research and clinical reagents. They are also excellent models for studying - infectious diseases such as syphilis and tuberculosis, which produce pathology that closely resembles that of human patients. Rabbit-specific infections such as myxomatosis are giving researchers insights into how pathogens and hosts can shape each other’s evolution.

Heterogeneity in retinoblastoma: a tale of molecules and models

Retinoblastoma, an intraocular pediatric cancer, develops in the embryonic retina following biallelic loss of RB1. However, there is a wide range of genetic and epigenetic changes that can affect RB1 resulting in different clinical outcomes. In addition, other transformations, such as MYCN amplification, generate particularly aggressive tumors, which may or may not be RB1 independent. Recognizing the cellular characteristics required for tumor development, by identifying the elusive cell-of-origin for retinoblastoma, would help us understand the development of these tumors. In this review we summarize the heterogeneity reported in retinoblastoma on a molecular, cellular and tissue level. We also discuss the challenging heterogeneity in current retinoblastoma models and suggest future platforms that could contribute to improved understanding of tumor initiation, progression and metastasis in retinoblastoma, which may ultimately lead to more patient-specific treatments.

Establishment of human metastatic colorectal cancer model in rabbit liver: A pilot study

Rationale and objectives

To develop a human metastatic colorectal cancer (mCRC) model in a rabbit liver.

Materials and methods

Immunosuppression in 4 adult New Zealand White rabbits weighing 3.5 to 4.5 kg was induced with daily subcutaneous injection of 15 mg/kg Cyclosporine A (CsA). On day 3 open mini-laparotomy was performed and 0.2 ml (1.8x10⁵ cells) suspension of HCT-116 and HT-29 human CRC cells were injected into the left and right medial lobe respectively. On day 10 the CsA dose was reduced to 10 mg/kg daily maintenance dose. Rabbits were weighed weekly, closely monitored for CsA side effects (weight loss, gingival hyperplasia and gut modification). Rabbits were sacrificed 5, 6, 7, and 8 weeks after cells injection. Liver tumors were collected for histopathology and immunohistochemical analysis.

Results

HT-29 Tumor growth was observed in 3 rabbits (75%). Tumors measured 3, 4 and 6 mm after 5, 6 and 8 weeks respectively. Microscopically, tumors contained hyperchromatic, pleomorphic cells that stained for monoclonal carcinoembryonic antigen (CEA), polyclonal CEA, cytokeratin 20, vascular markers (CD31, CD34), and vascular endothelial growth factor (VEGF) by immunohistochemistry, supporting involvement by the poorly differentiated HT-29 colorectal cancer cell line. No gross tumor growth or microscopic viability was observed from HCT-116 cell injection. CsA extra-hepatic manifestations included minimal gum hyperplasia and decrease in gut motility in 3 rabbits (75%), which was treated with Azithromycin 15 mg/kg and Cisapride 0.5 mg/kg every 12 hours, respectively.

Conclusion

We successfully developed a human metastatic colon cancer model in immunosuppressed rabbit liver using HT-29 cells.

Rabbit M1 and M2 macrophages can be induced by human recombinant GM-CSF and M-CSF

Macrophages can change their phenotype in response to environmental cues. Polarized macrophages are broadly classified into two groups: classical activated M1 and alternative activated M2. Characterization of human macrophages has been widely studied, but polarized macrophages in rabbits have not been characterized. We characterized rabbit macrophages that were polarized using human recombinant GM-CSF and M-CSF. GM-CSF-treated macrophages had higher mRNA expression of proinflammatory cytokines (M1 phenotype) than did the M-CSF-treated counterpart. By contrast, high levels of TGF-β and IL-10 expression (M2 phenotype) were found in M-CSF-treated macrophages. The present study may be useful to understand roles of polarized macrophages in rabbit disease models.

Genetic characterization of interleukins (IL-1α, IL-1β, IL-2, IL-4, IL-8, IL-10, IL-12A, IL-12B, IL-15 and IL-18) with relevant biological roles in lagomorphs

ILs, as essential innate immune modulators, are involved in an array of biological processes. In the European rabbit (Oryctolagus cuniculus) IL-1α, IL-1β, IL-2, IL-4, IL-8, IL-10, IL-12A, IL-12B, IL-15 and IL-18 have been implicated in inflammatory processes and in the immune response against rabbit hemorrhagic disease virus and myxoma virus infections. In this study we characterized these ILs in six Lagomorpha species (European rabbit, pygmy rabbit, two cottontail rabbit species, European brown hare and American pika). Overall, these ILs are conserved between lagomorphs, including in their exon/intron structure. Most differences were observed between leporids and American pika. Indeed, when comparing both, some relevant differences were observed in American pika, such as the location of the stop codon in IL-1α and IL-2, the existence of a different transcript in IL8 and the number of cysteine residues in IL-1β. Changes at N-glycosylation motifs were also detected in IL-1, IL-10, IL-12B and IL-15. IL-1α is the protein that presents the highest evolutionary distances, which is in contrast to IL-12A where the distances between lagomorphs are the lowest. For all these ILs, sequences of human and European rabbit are more closely related than between human and mouse or European rabbit and mouse.

The Biology of Retinoblastoma

Retinoblastoma, the most common primary intraocular cancer of childhood, is a malignancy arising in the developing retina. Tumor formation usually begins with mutation in both alleles of the retinoblastoma tumor suppressor gene RB1, followed by a series of other genetic alterations that correlate with the clinical stage and pathologic findings of the tumor. Analysis of sporadic and heritable retinoblastoma led to the development of Knudson's Two-Hit Hypothesis. The tumor suppressor RB1 gene codes for the retinoblastoma protein which is a key regulator of cellular replication via its binding to the E2F family of transcription factors and chromatin remodeling proteins. Studies of preclinical models of retinoblastoma in the form of transgenic mice and xenograft animal models have significantly contributed to the development of effective therapies for this disease. Research on retinoblastoma has paved the way toward understanding many of the mechanisms in cancer genetics.

Establishment of an Orthotopic Xenograft Mice Model of Retinoblastoma Suitable for Preclinical Testing

Retinoblastoma is a rare cancer that occurs during childhood. The goal of current and future therapeutic strategies is to conserve the eye and visual function without using external beam radiotherapy, which is known to increase the risk of secondary cancers in genetically predisposed patients. Multimodality therapy (usually intravenous but also intra-arterial and intravitreal chemotherapy, transpupillary thermotherapy, cryotherapy, or brachytherapy) has recently improved the eye salvage rate in retinoblastoma and has led to a decreased need for external beam radiotherapy. However, the treatment of advanced intraocular retinoblastoma remains a real challenge, especially in cases of vitreous and subretinal seeding. There is a need for alternative and less toxic therapies as well as for better ways to administer the drugs. Animal models are an integral part of preclinical research in the field of oncology. This paper describes the different xenograft rodent models published in the literature so far. We will also describe a new orthotopic xenografted retinoblastoma model in immunodeficient mice, which is suitable for preclinical assays. The xenograft model was established from tumor tissue obtained directly from surgical samples and closely mimics human retinoblastoma.

Retinoblastoma. Fifty years of progress. The LXXI Edward Jackson Memorial Lecture

PURPOSE

To review the progress made in understanding the genetic basis, molecular pathology, and treatment of retinoblastoma since the previous Jackson lecture on the topic was published 50 years ago.

DESIGN

Perspective based on personal experience and the literature.

METHODS

The literature regarding retinoblastoma was reviewed since 1963. Advances in understanding the biology and treatment of retinoblastoma provided context through the author's clinical, pathologic, and research experiences.

RESULTS

Retinoblastoma was first identified in the 1500s and defined as a unique clinicopathologic entity in 1809. Until the mid-1900s, knowledge advanced sporadically, with technological developments of ophthalmoscopy and light microscopy, and with the introduction of surgical enucleation, chemotherapy, and radiation therapy. During the last 50 years, research and treatment have progressed at an unprecedented rate owing to innovations in molecular biology and the development of targeted therapies. During this time period, the retinoblastoma gene was discovered; techniques for genetic testing for retinoblastoma were developed; and plaque brachytherapy, chemoreduction, intra-arterial chemotherapy, and intraocular injections of chemotherapeutic agents were successfully introduced.

CONCLUSIONS

Nearly all patients with retinoblastoma in developed countries can now be cured of their primary cancer--a remarkable achievement for a childhood cancer that once was uniformly fatal. Much of this success is owed to deciphering the role of the Rb gene, and the benefits of targeted therapies, such as chemoreduction with consolidation as well as intra-arterial and intravitreal chemotherapies. Going forward, the main challenge will be ensuring that access to care is available for all children, particularly those in developing countries.

Progress and prospects for genetic modification of nonhuman primate models in biomedical research

The growing interest of modeling human diseases using genetically modified (transgenic) nonhuman primates (NHPs) is a direct result of NHPs (rhesus macaque, etc.) close relation to humans. NHPs share similar developmental paths with humans in their anatomy, physiology, genetics, and neural functions; and in their cognition, emotion, and social behavior. The NHP model within biomedical research has played an important role in the development of vaccines, assisted reproductive technologies, and new therapies for many diseases. Biomedical research has not been the primary role of NHPs. They have mainly been used for safety evaluation and pharmacokinetics studies, rather than determining therapeutic efficacy. The development of the first transgenic rhesus macaque (2001) revolutionized the role of NHP models in biomedicine. Development of the transgenic NHP model of Huntington's disease (2008), with distinctive clinical features, further suggested the uniqueness of the model system; and the potential role of the NHP model for human genetic disorders. Modeling human genetic diseases using NHPs will continue to thrive because of the latest advances in molecular, genetic, and embryo technologies. NHPs rising role in biomedical research, specifically pre-clinical studies, is foreseeable. The path toward the development of transgenic NHPs and the prospect of transgenic NHPs in their new role in future biomedicine needs to be reviewed. This article will focus on the advancement of transgenic NHPs in the past decade, including transgenic technologies and disease modeling. It will outline new technologies that may have significant impact in future NHP modeling and will conclude with a discussion of the future prospects of the transgenic NHP model.

Animal models in retinoblastoma research

Advances in animal models of retinoblastoma have accelerated research in this field, aiding in understanding tumor progression and assessing therapeutic modalities. The distinct pattern of mutations and specific location of this unique intraocular tumor have paved the way for two types of models- those based on genetic mutations, and xenograft models. Retinoblastoma gene knockouts with an additional loss of p107, p130, p53 and using promoters of Nestin, Chx10, and Pax6 genes show histological phenotypic changes close to the human form of retinoblastoma. Conditional knockout in specific layers of the developing retina has thrown light on the origin of this tumor. The use of xenograft models has overcome the obstacle of time delay in the presentation of symptoms, which remains a crucial drawback of genetic models. With the advances in molecular and imaging technologies, the current research aims to develop models that mimic all the features of retinoblastoma inclusive of its initiation, progression and metastasis. The combination of genetic and xenograft models in retinoblastoma research has and will help to pave way for better understanding of retinoblastoma tumor biology and also in designing and testing effective diagnostic and treatment modalities.

Quantitative RT-PCR profiling of the rabbit immune response: assessment of acute Shigella flexneri infection

Quantitative reverse transcription PCR analysis is an important tool to monitor changes in gene expression in animal models. The rabbit is a widely accepted and commonly used animal model in the study of human diseases and infections by viral, fungal, bacterial and protozoan pathogens. Only a limited number of rabbit genes have, however, been analyzed by this method as the rabbit genome sequence remains unfinished. Recently, increasing coverage of the genome has permitted the prediction of a growing number of genes that are relevant in the context of the immune response. We hereby report the design of twenty-four quantitative PCR primer pairs covering common cytokines, chemoattractants, antimicrobials and enzymes for a rapid, sensitive and quantitative analysis of the rabbit immune response. Importantly, all primer pairs were designed to be used under identical experimental conditions, thereby enabling the simultaneous analysis of all genes in a high-throughput format. This tool was used to analyze the rabbit innate immune response to infection with the human gastrointestinal pathogen Shigella flexneri. Beyond the known inflammatory mediators, we identified IL-22, IL-17A and IL-17F as highly upregulated cytokines and as first responders to infection during the innate phase of the host immune response. This set of qPCR primers also provides a convenient tool for monitoring the rabbit immune response during infection with other pathogens and other inflammatory conditions.