Role of mechanotransduction mediated by YAP/TAZ in the treatment of neurogenic erectile dysfunction with low-intensity pulsed ultrasound.

BACKGROUND: Erectile dysfunction (ED) and weakness of the penis are processes related to hemodynamic alteration. Low-intensity pulsed ultrasound (LIPUS), as a new mechanical modality for the treatment of ED, deserves to be explored in depth for the biomechanical mechanisms it exerts. OBJECTIVE: The aim of this study was to explore the role of YAP/TAZ-mediated mechanotransduction in mechanical therapy for the treatment of neurogenic erectile dysfunction (NED). MATERIALS AND METHODS: Forty-two male SD rats (12 w old) were randomly divided into sham-operated (n = 14), bilateral cavernous nerve injury (BCNI, n = 14), and LIPUS-treated (n = 14) groups. Intracavernosal pressure/mean arterial pressure (ICP/MAP) was measured 14 and 28 days after treatment. Penile tissue specimens were collected for pathological examination, and the changes in YAP, TAZ, connective tissue growth factor (CTGF), CYR61, LATS1, and p38 mitogen-activated protein kinase expression levels were assessed by Western blot, real-time quantitative polymerase chain reaction (RT-qPCR) and immunological staining. RESULTS: Compared with BCNI, LIPUS significantly improved ICP/MAP levels and enhanced histopathological changes. The penile expression levels of YAP, TAZ, CTGF, and CYR61 were significantly downregulated in the BCNI group (p < 0.01), and LIPUS upregulated the expression levels of these proteins (p < 0.05). The expression levels of p-LATS1 and LATS1 were not significantly different among the groups (p > 0.05). Interestingly, the expression level of p-p38/p38 significantly increased in BCNI rats (p < 0.05), which was reversed by LIPUS treatment (p < 0.05). However, the p38 inhibitor SB203580 did not change the expression of YAP/TAZ in rat primary smooth muscle cells or mouse MOVAS cells (p > 0.05). DISCUSSION AND CONCLUSION: LIPUS can effectively improve penile erectile function in NED rats. The underlying mechanism may be related to the regulation of YAP/TAZ-mediated mechanotransduction. However, the upstream regulatory signal may differ from the classical Hippo pathway.

Roles of neuronal toll-like receptors in neuropathic pain and central nervous system injuries and diseases.

Toll-like receptors (TLRs) are innate immune receptors that are expressed in immune cells as well as glia and neurons of the central and peripheral nervous systems. They are best known for their role in the host defense in response to pathogens and for the induction of inflammation in infectious and non-infectious diseases. In the central nervous system (CNS), TLRs modulate glial and neuronal functions as well as innate immunity and neuroinflammation under physiological or pathophysiological conditions. The majority of the studies on TLRs in CNS pathologies investigated their overall contribution without focusing on a particular cell type, or they analyzed TLRs in glia and infiltrating immune cells in the context of neuroinflammation and cellular activation. The role of neuronal TLRs in CNS diseases and injuries has received little attention and remains underappreciated. The primary goal of this review is to summarize findings demonstrating the pivotal and unique roles of neuronal TLRs in neuropathic pain, Alzheimer's disease, Parkinson's disease and CNS injuries. We discuss how the current findings warrant future investigations to better define the specific contributions of neuronal TLRs to these pathologies. We underline the paucity of information regarding the role of neuronal TLRs in other neurodegenerative, demyelinating, and psychiatric diseases. We draw attention to the importance of broadening research on neuronal TLRs in view of emerging evidence demonstrating their distinctive functional properties.

Nerve injury and repair in a ketogenic milieu: A systematic review of traumatic injuries to the spinal cord and peripheral nervous tissue.

Dietary interventions such as intermittent fasting and the ketogenic diet have demonstrated neuroprotective effects in various models of neurological insult. However, there has been a lack of evaluation of these interventions from a surgical perspective despite their potential to augment reparative processes that occur following nerve injury. Thus, we sought to analyze the effects of these dietary regimens on nerve regeneration and repair by critical appraisal of the literature. Following PRISMA guidelines, a systematic review was performed to identify studies published between 1950 and 2020 that examined the impact of either the ketogenic diet or intermittent fasting on traumatic injuries to the spinal cord or peripheral nerves. Study characteristics and outcomes were analyzed for each included article. A total of 1,890 articles were reviewed, of which 11 studies met inclusion criteria. Each of these articles was then assessed based on a variety of qualitative parameters, including type of injury, diet composition, timing, duration, and outcome. In total, seven articles examined the ketogenic diet, while four examined intermittent fasting. Only three studies examined peripheral nerves. Neuroprotective effects manifested as either improved histological or functional benefits in most of the included studies. Overall, we conclude that intermittent fasting and the ketogenic diet may promote neuroprotection and facilitate the regeneration and repair of nerve fibers following injury; however, lack of consistency between the studies in terms of animal models, diet compositions, and timing of dietary interventions preclude synthesis of their outcomes as a whole.

α-Synuclein in traumatic and vascular diseases of the central nervous system.

α-Synuclein (α-Syn) is a small, soluble, disordered protein that is widely expressed in the nervous system. Although its physiological functions are not yet fully understood, it is mainly involved in synaptic vesicle transport, neurotransmitter synthesis and release, cell membrane homeostasis, lipid synthesis, mitochondrial and lysosomal activities, and heavy metal removal. The complex and inconsistent pathological manifestations of α-Syn are attributed to its structural instability, mutational complexity, misfolding, and diverse posttranslational modifications. These effects trigger mitochondrial dysfunction, oxidative stress, and neuroinflammatory responses, resulting in neuronal death and neurodegeneration. Several recent studies have discovered the pathogenic roles of α-Syn in traumatic and vascular central nervous system diseases, such as traumatic spinal cord injury, brain injury, and stroke, and in aggravating the processes of neurodegeneration. This review aims to highlight the structural and pathophysiological changes in α-Syn and its mechanism of action in traumatic and vascular diseases of the central nervous system.

Effects of Pacap on Schwann Cells: Focus on Nerve Injury.

Schwann cells, the most abundant glial cells of the peripheral nervous system, represent the key players able to supply extracellular microenvironment for axonal regrowth and restoration of myelin sheaths on regenerating axons. Following nerve injury, Schwann cells respond adaptively to damage by acquiring a new phenotype. In particular, some of them localize in the distal stump to form the Bungner band, a regeneration track in the distal site of the injured nerve, whereas others produce cytokines involved in recruitment of macrophages infiltrating into the nerve damaged area for axonal and myelin debris clearance. Several neurotrophic factors, including pituitary adenylyl cyclase-activating peptide (PACAP), promote survival and axonal elongation of injured neurons. The present review summarizes the evidence existing in the literature demonstrating the autocrine and/or paracrine action exerted by PACAP to promote remyelination and ameliorate the peripheral nerve inflammatory response following nerve injury.

Modelling human CNS injury with human neural stem cells in 2- and 3-Dimensional cultures.

The adult human central nervous system (CNS) has very limited regenerative capability, and injury at the cellular and molecular level cannot be studied in vivo. Modelling neural damage in human systems is crucial to identifying species-specific responses to injury and potentially neurotoxic compounds leading to development of more effective neuroprotective agents. Hence we developed human neural stem cell (hNSC) 3-dimensional (3D) cultures and tested their potential for modelling neural insults, including hypoxic-ischaemic and Ca2+-dependent injury. Standard 3D conditions for rodent cells support neuroblastoma lines used as human CNS models, but not hNSCs, but in all cases changes in culture architecture alter gene expression. Importantly, response to damage differs in 2D and 3D cultures and this is not due to reduced drug accessibility. Together, this study highlights the impact of culture cytoarchitecture on hNSC phenotype and damage response, indicating that 3D models may be better predictors of in vivo response to damage and compound toxicity.

Cervical Spine Movement in a Cadaveric Model of Severe Spinal Instability: A Study Comparing Tracheal Intubation with 4 Different Laryngoscopes.

BACKGROUND: This study compared the Macintosh blade direct laryngoscope, Glidescope, C-Mac d-Blade, and McGrath MAC X-blade video laryngoscopes in 2 cadaveric models with severe cervical spinal instability. We hypothesized that the Glidescope video laryngoscope would allow for intubation with the least amount of cervical spine movement. Our secondary endpoints were glottic visualization and intubation success. METHODS: In total, 2 fresh cadavers underwent maximal surgical destabilization from the craniocervical junction to the cervicothoracic junction by a neurosurgical spine specialist, with subsequent neutral positioning of the heads with surgical head fixation devices. On each cadaver, 8 experienced anesthesiologists performed four intubations with the 4 laryngoscopes in random order. Lateral radiographic measurements determined vertebral displacement during intubation. RESULTS: Cervical spine displacements were not significantly different amongst video laryngoscopes. Cormack-Lehane Grade 1 views were achieved with all attempts with each of the 3 video laryngoscopes; intubation attempts with the Macintosh blade achieved only grade 3 or grade 4 views. Intubation was successful every time with a video laryngoscope but only during 1 of 16 intubation attempts with the Macintosh blade. CONCLUSIONS: In a cadaveric model with maximally destabilized cervical spines, cervical spine movement was observed during attempted laryngoscopy using each of 3 video laryngoscopes, although there was no significant difference between the laryngoscopes. Given cervical spine displacement occurred, these video laryngoscopes do not prevent cervical spine motion during laryngoscopy. However, with improved glottic visualization and intubation success, video laryngoscopes are superior to the Macintosh blade in both cervical spine safety and intubation efficacy in the model studied.

Systemic Immune Response to Traumatic CNS Injuries-Are Extracellular Vesicles the Missing Link?

Inflammation following traumatic injury to the central nervous system (CNS) persists long after the primary insult and is known to exacerbate cell death and worsen functional outcomes. Therapeutic interventions targeting this inflammation have been unsuccessful, which has been attributed to poor bioavailability owing to the presence of blood-CNS barrier. Recent studies have shown that the magnitude of the CNS inflammatory response is dependent on systemic inflammatory events. The acute phase response (APR) to CNS injury presents an alternative strategy to modulating the secondary phase of injury. However, the communication pathways between the CNS and the periphery remain poorly understood. Extracellular vesicles (EVs) are membrane bound nanoparticles that are regulators of intercellular communication. They are shed from cells of the CNS including microglia, astrocytes, neurons and endothelial cells, and are able to cross the blood-CNS barrier, thus providing an attractive candidate for initiating the APR after acute CNS injury. The purpose of this review is to summarize the current evidence that EVs play a critical role in the APR following CNS injuries.

Nitrous Oxide Impairs Axon Regeneration after Nervous System Injury in Male Rats.

BACKGROUND: Nitrous oxide can induce neurotoxicity. The authors hypothesized that exposure to nitrous oxide impairs axonal regeneration and functional recovery after central nervous system injury. METHODS: The consequences of single and serial in vivo nitrous oxide exposures on axon regeneration in four experimental male rat models of nervous system injury were measured: in vitro axon regeneration in cell culture after in vivo nitrous oxide administration, in vivo axon regeneration after sharp spinal cord injury, in vivo axon regeneration after sharp optic nerve injury, and in vivo functional recovery after blunt contusion spinal cord injury. RESULTS: In vitro axon regeneration 48 h after a single in vivo 70% N2O exposure is less than half that in the absence of nitrous oxide (mean ± SD, 478 ± 275 um; n = 48) versus 210 ± 152 um (n = 48; P < 0.0001). A single exposure to 80% N2O inhibits the beneficial effects of folic acid on in vivo axonal regeneration after sharp spinal cord injury (13.4 ± 7.1% regenerating neurons [n = 12] vs. 0.6 ± 0.7% regenerating neurons [n = 4], P = 0.004). Serial 80% N2O administration reverses the benefit of folic acid on in vivo retinal ganglion cell axon regeneration after sharp optic nerve injury (1277 ± 180 regenerating retinal ganglion cells [n = 7] vs. 895 ± 164 regenerating retinal ganglion cells [n = 7], P = 0.005). Serial 80% N2O exposures reverses the benefit of folic acid on in vivo functional recovery after blunt spinal cord contusion (estimate for fixed effects ± standard error of the estimate: folic acid 5.60 ± 0.54 [n = 9] vs. folic acid + 80% N2O 5.19 ± 0.62 [n = 7], P < 0.0001). CONCLUSIONS: These data indicate that nitrous oxide can impair the ability of central nervous system neurons to regenerate axons after sharp and blunt trauma.

Peripheral nerve injuries in the pediatric population: a review of the literature. Part I: traumatic nerve injuries.

OBJECTIVE: This article reviews the clinical results that can be obtained after repair of a traumatic peripheral nerve injury in the pediatric population. METHODS: A systematic review of the published literature has been made. RESULTS: Functional outcome after major nerve injuries is sometimes disappointing in adults. However, children have been reported to experience much better functional results after nerve repair than adults. Moreover, recovery generally is faster in children. The superior capacity of children's central nervous system to adapt to external or internal environmental changes (neural plasticity) and the shorter recovery distance from the axon repair site to the target muscle are claimed to be crucial determinants of their favorable outcomes. Moreover, even in the pediatric population, it has been demonstrated that functional results are better the younger the patient is, including better clinical results in those injured in early childhood (< 6 years old) than in those injured in adolescence. Other favorable prognostic factors include the type of nerve injury (with complete transections doing less well than crush injuries) and the timing of surgery (with better outcomes after early repairs). CONCLUSIONS: All efforts should be done to repair in a timely and adequate fashion traumatic peripheral nerve injuries in children, as the results are good.

Evaluation of nerve growth factor (NGF) treated mesenchymal stem cells for recovery in neurotmesis model of peripheral nerve injury.

BACKGROUND: Peripheral nerve damages are a relatively common type of the nervous system injuries. Although peripheral nerves show some capacity of regeneration after injury, the extent of regeneration is not remarkable. The present study aimed to evaluate the effect of NGF treated mesenchymal stem cells on regeneration of transected sciatic nerve. MATERIALS AND METHODS: In this experimental study, forty-two male Wistar.rats (180-200 g) were randomly divided into 6 groups (n = 7) including control, Membrane + Cell (Mem + Cell), NGF group, NGF + Cell group, NGF + Mem group and NGF + Mem + Cell group. Regeneration of sciatic nerve was evaluated using behavioral analysis, electrophysiological assessment and histological examination. RESULTS: The rats in the NGF + Mem + Cell group showed significant decrease in sciatic functional index (SFI) and hot water paw immersion test during the 2nd to 8th weeks after surgery. (p < 0.001). At 8 weeks after surgery, electrophysiological findings showed that amplitude increased and latency decreased significantly in NGF + Mem + Cell group (p < 0.001). Measured histological parameters showed that number of nerve fibers, number of vessels and percent of vessel area also increased significantly in NGF + Mem + Cell group (p < 0.05). CONCLUSION: The present study showed that NGF in accompany with mesenchymal stem cells improved electrophysiological and histological indices.

Long-Term Regular Eccentric Exercise Decreases Neuropathic Pain-like Behavior and Improves Motor Functional Recovery in an Axonotmesis Mouse Model: the Role of Insulin-like Growth Factor-1.

Although training programs with regular eccentric (ECC) exercise are more commonly used for improving muscular strength and mobility, ECC exercise effects upon functional recovery of the sciatic nerve has not yet been determined. After sciatic nerve crush, different mice groups were subjected to run on the treadmill for 30 min at a speed of 6, 10, or 14 m/min with - 16° slope, 5 days per week, over 8 weeks. During the training time, neuropathic pain-like behavior (mechanical and cold hyperalgesia) was assessed and functional recovery was determined with the grip strength test and the Sciatic Functional and Static indexes (SFI and SSI). After 9 weeks, triceps surae muscle weight and morphological alterations were assessed. Tumor necrosis factor alpha (TNF-α), interleukin-1ß (IL-1ß), interleukin-4 (IL-4), interleukin-1Ra (IL-1Ra), insulin-like growth factor-1 (IGF-1) levels, and markers pro- and anti-inflammatory and regeneration, respectively, were quantified in the muscle and sciatic nerve on day 14 post-crushing. Exercised groups presented less neuropathic pain-like behavior and better functional recovery than non-exercised groups. Biochemically, ECC exercise reduced TNF-α increase in the muscle. ECC exercise increased sciatic nerve IGF-1 levels in sciatic nerve crush-subjected animals. These findings provide new evidence indicating that treatment with ECC might be a potential approach for neuropathy induced by peripheral nerve injury.

[Myositis Ossificans Traumatica in the Craniocervical Junction: A Case Report and Review of Literature]. / Myositis ossificans traumatica im kraniozervikalen Übergang ­ Fallbericht und Literaturübersicht.

Background Myosits ossificans (MO) is a rare but important differential diagnosis for a heterotrophic bony tumor in the muscles. It is often misdiagnosed as a malignant tumor. With a previous trauma the diagnosis is myositis ossificans traumatic (MOT). In most cases, it is benign and predominantly seen in the big muscles. But there can be malignant etiologies too. Case Description We report a rare case of MO in the muscle of the craniocervical junction. This 37-year-old woman had a riding accident years ago. Because of persisting pain and cervical dysfunction, we did a total resection. Clinical Implications MOT is a benign tumor that can be treated conservative in most cases. In case of persistent pain or neurological deficits, and especially for securing diagnosis, surgical resection is recommended.

Epigenetic Regulation of Axon Regeneration after Neural Injury.

When peripheral axons are damaged, neuronal injury signaling pathways induce transcriptional changes that support axon regeneration and consequent functional recovery. The recent development of bioinformatics techniques has allowed for the identification of many of the regeneration-associated genes that are regulated by neural injury, yet it remains unclear how global changes in transcriptome are coordinated. In this article, we review recent studies on the epigenetic mechanisms orchestrating changes in gene expression in response to nerve injury. We highlight the importance of epigenetic mechanisms in discriminating efficient axon regeneration in the peripheral nervous system and very limited axon regrowth in the central nervous system and discuss the therapeutic potential of targeting epigenetic regulators to improve neural recovery.

Serum-free bioprocessing of adult human and rodent skin-derived Schwann cells: implications for cell therapy in nervous system injury.

Peripheral nerve injury affects 2.8% of trauma patients with severe cases often resulting in long-lived permanent disability, despite nerve repair surgery. Autologous Schwann cell (SC) therapy currently provides an exciting avenue for improved outcomes for these patients, particularly with the possibility to derive SCs from easily-accessible adult skin. However, due to current challenges regarding the efficient expansion of these cells, further optimization is required before they can be seriously considered for clinical application. Here, a microcarrier-based bioreactor system is proposed as a means to scale-up large numbers of adult skin-derived SCs for transplantation into the injured nerve. Bioprocessing parameters that allow for the expansion of adult rodent SCs have been identified, whilst maintaining similar rates of proliferation (as compared to static-grown SCs), expression of SC markers, and, importantly, their capacity to myelinate axons following transplant into the injured sciatic nerve. The same bioprocessing parameters can be applied to SCs derived from adult human skin, and like rodent cells, they sustain their proliferative potential and expression of SC markers. Taken together, this dataset demonstrates the basis for a scalable bioprocess for the production of SCs, an important step towards clinical use of these cells as an adjunct therapy for nerve repair. Copyright © 2017 John Wiley & Sons, Ltd.

Differentiation of Pre- and Postganglionic Nerve Injury Using MRI of the Spinal Cord.

Brachial plexus injury (BPI) is a devastating type of nerve injury, potentially causing loss of motor and sensory function. Principally, BPI is either categorized as preganglionic or postganglionic, with the early establishment of injury level being crucial for choosing the correct treatment strategy. Despite diagnostic advances, the need for a reliable, non-invasive method for establishing the injury level remains. We studied the usefulness of in vivo magnetic resonance imaging (MRI) of the spinal cord for determination of injury level. The findings were related to neuronal and glial changes. Rats underwent unilateral L4 & L5 ventral roots avulsion or sciatic nerve axotomy. The injuries served as models for pre- and postganglionic BPI, respectively. MRI of the L4/L5 spinal cord segments 4 weeks after avulsion showed ventral horn (VH) shrinkage on the injured side compared to the uninjured side. Axotomy induced no change in the VH size on MRI. Following avulsion, histological sections of L4/L5 revealed shrinkage in the VH grey matter area occupied by NeuN-positive neurons, loss of microtubular-associated protein-2 positive dendritic branches (MAP2), pan-neurofilament positive axons (PanNF), synaptophysin-positive synapses (SYN) and increase in immunoreactivity for the microglial OX42 and astroglial GFAP markers. Axotomy induced no changes in NeuN-reactivity, modest decrease of MAP2 immunoreactivity, no changes in SYN and PanNF labelling, and a modest increase in OX42 and SYN labeling. Histological and radiological findings were congruent when assessing changes after axotomy, while MRI somewhat underestimated the shrinkage. This study indicates a potential diagnostic value of structural spinal cord MRI following BPI.

Methods of Drug Delivery in Neurotrauma.

The central nervous system (CNS) is protected by blood-brain barrier (BBB) and blood-cerebrospinal-fluid (CSF) barrier that limit toxic agents and most molecules from penetrating the brain and spinal cord. However, these barriers also prevent most pharmaceuticals from entering into the CNS. Drug delivery to the CNS following neurotrauma is complicated. Although studies have shown BBB permeability increases in various TBI models, it remains as the key mitigating factor for delivering drugs into the CNS. The commonly used methods for drug delivery in preclinical neurotrauma studies include intraperitoneal, subcutaneous, intravenous, and intracerebroventricular delivery. It should be noted that for a drug to be successfully translated into the clinic, it needs to be administered preclinically as it would be anticipated to be administered to patients. And this likely leads to better dose selection of the drug, as well as recognition of any possible side effects, prior to transition into a clinical trial. Additionally, novel approach that is noninvasive and yet circumvents BBB, such as drug delivery through nerve pathways innervating the nasal passages, needs to be investigated in animal models, as it may provide a viable drug delivery method for patients who sustain mild CNS injury or require chronic treatments. Therefore, the focus of this chapter is to present rationales and methods for delivering drugs by IV infusion via the jugular vein, and intranasally in preclinical studies.

Bridging the Gap of Standardized Animals Models for Blast Neurotrauma: Methodology for Appropriate Experimental Testing.

Recent military combat has heightened awareness to the complexity of blast-related traumatic brain injuries (bTBI). Experiments using animal, cadaver, or biofidelic physical models remain the primary measures to investigate injury biomechanics as well as validate computational simulations, medical diagnostics and therapies, or protection technologies. However, blast injury research has seen a range of irregular and inconsistent experimental methods for simulating blast insults generating results which may be misleading, cannot be cross-correlated between laboratories, or referenced to any standard for exposure. Both the US Army Medical Research and Materiel Command and the National Institutes of Health have noted that there is a lack of standardized preclinical models of TBI. It is recommended that the blast injury research community converge on a consistent set of experimental procedures and reporting of blast test conditions. This chapter describes the blast conditions which can be recreated within a laboratory setting and methodology for testing in vivo models within the appropriate environment.

Cellular Mechanisms and Behavioral Outcomes in Blast-Induced Neurotrauma: Comparing Experimental Setups.

Blast-induced neurotrauma (BINT) has increased in incidence over the past decades and can result in cognitive issues that have debilitating consequences. The exact primary and secondary mechanisms of injury have not been elucidated and appearance of cellular injury can vary based on many factors, such as blast overpressure magnitude and duration. Many methodologies to study blast neurotrauma have been employed, ranging from open-field explosives to experimental shock tubes for producing free-field blast waves. While there are benefits to the various methods, certain specifications need to be accounted for in order to properly examine BINT. Primary cell injury mechanisms, occurring as a direct result of the blast wave, have been identified in several studies and include cerebral vascular damage, blood-brain barrier disruption, axonal injury, and cytoskeletal damage. Secondary cell injury mechanisms, triggered subsequent to the initial insult, result in the activation of several molecular cascades and can include, but are not limited to, neuroinflammation and oxidative stress. The collective result of these secondary injuries can lead to functional deficits. Behavioral measures examining motor function, anxiety traits, and cognition/memory problems have been utilized to determine the level of injury severity. While cellular injury mechanisms have been identified following blast exposure, the various experimental models present both concurrent and conflicting results. Furthermore, the temporal response and progression of pathology after blast exposure have yet to be detailed and remain unclear due to limited resemblance of methodologies. This chapter summarizes the current state of blast neuropathology and emphasizes the need for a standardized preclinical model of blast neurotrauma.

Experimental Models for Neurotrauma Research.

Physical trauma in the central nervous system (CNS) is usually the result of a number of forces in different directions and dimensions. A large number of experimental models have been developed to improve the possibilities to understand the outcome of CNS trauma. In this chapter, we will describe the need for a variety of experimental models for research on traumatic brain injury (TBI) and spinal cord injury (SCI). Models can serve different needs, such as: to test new treatments for injuries, to reveal thresholds for injuries, to provide a better understanding of injury mechanisms, or to test tools and methods for translation between experiments and clinical data. In this chapter, we will discuss on the validation of models and translation between experimental and clinical studies.