Large animal models for Huntington's disease research

Huntington'sdisease(HD)isahereditary neurodegenerative disorder for which there is currently no effectivetreatmentavailable.Consequently,the development of appropriate disease models is critical to thoroughly investigate disease progression.The genetic basis of HD involves the abnormal expansion of CAG repeats in the huntingtin(HTT)gene,leading to the expansion of a polyglutamine repeat in the HTT protein.Mutant HTT carrying the expanded polyglutamine repeat undergoes misfolding and forms aggregates in the brain,which precipitate selective neuronal loss in specific brain regions.Animal models play an important role in elucidating the pathogenesis of neurodegenerative disorders such as HD and in identifying potential therapeutic targets.Due to the marked species differences between rodents and larger animals,substantial efforts have been directed toward establishing large animal models for HD research.These models are pivotal for advancing the discovery of novel therapeutic targets,enhancing effective drug delivery methods,and improving treatment outcomes.We have explored the advantages of utilizing large animal models,particularly pigs,in previous reviews.Since then,however,significant progress has been made in developing more sophisticated animal models that faithfully replicate the typical pathology of HD.In the current review,we provide a comprehensive overview of large animal models of HD,incorporating recent findings regarding the establishment of HD knock-in(KI)pigs and their genetic therapy.We also explore the utilization of large animal models in HD research,with a focus on sheep,non-human primates(NHPs),and pigs.Our objective is to provide valuable insights into the application of these large animal models for the investigation and treatment of neurodegenerative disorders.

Large animal models of cardiac ischemia-reperfusion injury:Where are we now?

Large animal models of cardiac ischemia-reperfusion are critical for evaluation of the efficacy of cardioprotective interventions prior to clinical translation.Nonetheless,current cardioprotective strategies/interventions formulated in preclinical cardiovascular research are often limited to small animal models,which are not transferable or reproducible in large animal models due to different factors such as:(i)complex and varied features of human ischemic cardiac disease(ICD),which are challenging to mimic in animal models,(ii)significant differences in surgical techniques applied,and(iii)differences in cardiovascular anatomy and physiology between small versus large animals.This article highlights the advantages and disadvantages of different large animal models of preclinical cardiac ischemic reperfusion injury(IRI),as well as the different methods used to induce and assess IRI,and the obstacles faced in using large animals for translational research in the settings of cardiac IR.

Large animal ischemic stroke models: replicating human stroke pathophysiology

The high morbidity and mortality rate of ischemic stroke in humans has led to the development of numerous animal models that replicate human stroke to further understand the underlying pathophysiology and to explore potential therapeutic interventions.Although promising therapeutics have been identified using these animal models,with most undergoing significant testing in rodent models,the vast majority of these interventions have failed in human clinical trials.This failure of preclinical translation highlights the critical need for better therapeutic assessment in more clinically relevant ischemic stroke animal models.Large animal models such as non-human primates,sheep,pigs,and dogs are likely more predictive of human responses and outcomes due to brain anatomy and physiology that are more similar to humans-potentially making large animal testing a key step in the stroke therapy translational pipeline.The objective of this review is to highlight key characteristics that potentially make these gyrencephalic,large animal ischemic stroke models more predictive by comparing pathophysiological responses,tissue-level changes,and model limitations.

New pathogenic insights from large animal models of neurodegenerative diseases

Animal models are essential for investigating the pathogenesis and developing the treatment of human diseases.Identification of genetic mutations responsible for neurodegenerative diseases has enabled the creation of a large number of small animal models that mimic genetic defects found in the affected individuals.Of the current animal models,rodents with genetic modifications are the most commonly used animal models and provided important insights into pathogenesis.However,most of genetically modified rodent models lack overt neurodegeneration,imposing challenges and obstacles in utilizing them to rigorously test the therapeutic effects on neurodegeneration.Recent studies that used CRISPR/Cas9-targeted large animal(pigs and monkeys)have uncovered important pathological events that resemble neurodegeneration in the patient’s brain but could not be produced in small animal models.Here we highlight the unique nature of large animals to model neurodegenerative diseases as well as the limitations and challenges in establishing large animal models of neurodegenerative diseases,with focus on Huntington disease,Amyotrophic lateral sclerosis,and Parkinson diseases.We also discuss how to use the important pathogenic insights from large animal models to make rodent models more capable of recapitulating important pathological features of neurodegenerative diseases.

Localization of the hydrogen sulfide and oxytocin systems at the depth of the sulci in a porcine model of acute subdural hematoma

In the porcine model discussed in this review,the acute subdural hematoma was induced by subdural injection of autologous blood over the left parietal cortex,which led to a transient elevation of the intracerebral pressure,measured by bilateral neuromonitoring.The hematoma-induced brain injury was associated with albumin extravasation,oxidative stress,reactive astrogliosis and microglial activation in the ipsilateral hemisphere.Further proteins and injury markers were validated to be used for immunohistochemistry of porcine brain tissue.The cerebral expression patterns of oxytocin,oxytocin receptor,cystathionine-γ-lyase and cystathionine-β-synthase were particularly interesting:these four proteins all co-localized at the base of the sulci,where pressure-induced brain injury elicits maximum stress.In this context,the pig is a very relevant translational model in contrast to the rodent brain.The structure of the porcine brain is very similar to the human:the presence of gyri and sulci(gyrencephalic brain),white matter to grey matter proportion and tentorium cerebelli.Thus,pressure-induced injury in the porcine brain,unlike in the rodent brain,is reflective of the human pathophysiology.

A Hierarchical Helical Carbon Nanotube Fiber Artificial Ligament

For the optimal functional recovery of force-transmitting connective tissues,obtaining grafts that are mechanically robust and integrating them with host bone effectively to tolerate high loads during violent joint motions is both crucial and challenging.Recent research proposes that a hierarchical helical carbon nanotube fiber,which has the considerably high mechanical strength,and can integrate with the host bone and restore movement in animals,is a very promising artificial ligament.The above research marks a significant development in artificial ligament via the innovative utilization of hierarchical helical carbon nanotube fiber.

Immunological and functional features of decellularized xenogeneic heart valves after transplantation into GGTA1-KO pigs

Decellularization of xenogeneic heart valves might lead to excellent regenerative implants,from which many patients could benefit.However,this material carries various xenogeneic epitopes and thus bears a considerable inherent immunological risk.Here,we investigated the regenerative and immunogenic potential of xenogeneic decellularized heart valve implants using pigs deficient for the galactosyltransferase gene(GGTA1-KO)as novel large animal model.Decellularized aortic and pulmonary heart valves obtained from sheep,wild-type pigs or GGTA1-KO pigs were implanted into GGTA1-KO pigs for 3,or 6 months,respectively.Explants were analyzed histologically,immunhistologically(CD3,CD21 and CD172a)and anti-aGal antibody serum titers were determined by ELISA.Xenogeneic sheep derived implants exhibited a strong immune reaction upon implantation into GGTA1-KO pigs,characterized by massive inflammatory cells infiltrates,presence of foreign body giant cells,a dramatic increase of anti-aGal antibody titers and ultimately destruction of the graft,whereas wild-type porcine grafts induced only a mild reaction in GGTA1-KO pigs.Allogeneic implants,wild-type/wild-type and GGTA1-KO/GGTA1-KO valves did not induce a measurable immune reaction.Thus,GGTA1-KO pigs developed a‘human-like’immune response toward decellularized xenogeneic implants showing that immunogenicity of xenogeneic implants is not sufficiently reduced by decellularization,which detracts from their regenerative potential.