3D bioprinting-a model for skin aging

Human lifespan continues to extend as an unprecedented number of people reach their seventh and eighth decades of life, unveiling chronic conditions that affect the older adult. Age-related skin conditions include senile purpura, seborrheic keratoses, pemphigus vulgaris, bullous pemphigoid, diabetic foot wounds and skin cancer. Current methods of drug testing prior to clinical trials require the use of pre-clinical animal models, which are often unable to adequately replicate human skin response. Therefore, a reliable model for aged human skin is needed. The current challenges in developing an aged human skin model include the intrinsic variability in skin architecture from person to person. An ideal skin model would incorporate innate functionality such as sensation, vascularization and regeneration. The advent of 3D bioprinting allows us to create human skin equivalent for use as clinical-grade surgical graft, for drug testing and other needs. In this review, we describe the process of human skin aging and outline the steps to create an aged skin model with 3D bioprinting using skin cells (i.e. keratinocytes, fibroblasts and melanocytes). We also provide an overview of current bioprinted skin models, associated limitations and direction for future research.

Senescent cardiomyocytes contribute to cardiac dysfunction following myocardial infarction

Myocardial infarction is a leading cause of morbidity and mortality. While reperfusion is now standard therapy, pathological remodeling leading to heart failure remains a clinical problem. Cellular senescence has been shown to contribute to disease pathophysiology and treatment with the senolytic navitoclax attenuates inflammation, reduces adverse myocardial remodeling and results in improved functional recovery. However, it remains unclear which senescent cell populations contribute to these processes. To identify whether senescent cardiomyocytes contribute to disease pathophysiology post-myocardial infarction, we established a transgenic model in which p16 (CDKN2A) expression was specifically knocked-out in the cardiomyocyte population. Following myocardial infarction, mice lacking cardiomyocyte p16 expression demonstrated no difference in cardiomyocyte hypertrophy but exhibited improved cardiac function and significantly reduced scar size in comparison to control animals. This data demonstrates that senescent cardiomyocytes participate in pathological myocardial remodeling. Importantly, inhibition of cardiomyocyte senescence led to reduced senescence-associated inflammation and decreased senescence-associated markers within other myocardial lineages, consistent with the hypothesis that cardiomyocytes promote pathological remodeling by spreading senescence to other cell-types. Collectively this study presents a novel demonstration that senescent cardiomyocytes are major contributors to myocardial remodeling and dysfunction following a myocardial infarction. Therefore, to maximize the potential for clinical translation, it is important to further understand the mechanisms underlying cardiomyocyte senescence and how to optimize senolytic strategies to target this cell lineage.

IDENTIFICATION AND INVESTIGATION OF SENESCENT CELLS IN SKELETAL MUSCLE AGING

Skeletal muscle aging is marked by the loss and atrophy of resident fibers, and the accumulation of functionally diverse cell types including fibroblasts, adipocytes, and immune cells. Senescent cells amass in multiple tissues with advancing age where they contribute to aging, chronic disease, and physical decline. The role of senescence in mediating muscle aging has become a popular and sometimes contentious topic. However, to date, this concept has not been methodically tested. In this study, we characterized the changes in cell abundance and, importantly, cell-specific transcriptional profiles with skeletal muscle aging using scRNAseq. Interestingly, we identified a small population of p16 positive fibro-adipogenic progenitors (FAPs) which, upon further investigation using immunohistochemical methods, were found to express other senescence markers. This subpopulation of FAPs did not exhibit elevation in p21 levels with age. Instead, terminally differentiated myofibers were the source of the p21 increase. Myofibers with high p21 expression exhibit a strong inflammatory phenotype, which includes activated p53 signaling pathways together with strong cytokine-cytokine receptor interactions. We further identified large amounts of cross-talk between different cell types, suggesting that senescent FAPs and myofibers could contribute to skeletal muscle aging in a paracrine manner. Importantly, these observations in mice were confirmed in human samples, suggesting the strong translational power of these findings.

IDENTIFICATION AND INVESTIGATION OF SENESCENT CELLS IN SKELETAL MUSCLE AGING

Skeletal muscle aging is marked by the loss and atrophy of resident fibers, and the accumulation of functionally diverse cell types including fibroblasts, adipocytes, and immune cells. Senescent cells amass in multiple tissues with advancing age where they contribute to aging, chronic disease, and physical decline. The role of senescence in mediating muscle aging has become a popular and sometimes contentious topic. However, to date, this concept has not been methodically tested. In this study, we characterized the changes in cell abundance and, importantly, cell-specific transcriptional profiles with skeletal muscle aging using scRNAseq. Interestingly, we identified a small population of p16 positive fibro-adipogenic progenitors (FAPs) which, upon further investigation using immunohistochemical methods, were found to express other senescence markers. This subpopulation of FAPs did not exhibit elevation in p21 levels with age. Instead, terminally differentiated myofibers were the source of the p21 increase. Myofibers with high p21 expression exhibit a strong inflammatory phenotype, which includes activated p53 signaling pathways together with strong cytokine-cytokine receptor interactions. We further identified large amounts of cross-talk between different cell types, suggesting that senescent FAPs and myofibers could contribute to skeletal muscle aging in a paracrine manner. Importantly, these observations in mice were confirmed in human samples, suggesting the strong translational power of these findings.

IDENTIFICATION AND INVESTIGATION OF SENESCENT CELLS IN SKELETAL MUSCLE AGING

Skeletal muscle aging is marked by the loss and atrophy of resident fibers, and the accumulation of functionally diverse cell types including fibroblasts, adipocytes, and immune cells. Senescent cells amass in multiple tissues with advancing age where they contribute to aging, chronic disease, and physical decline. The role of senescence in mediating muscle aging has become a popular and sometimes contentious topic. However, to date, this concept has not been methodically tested. In this study, we characterized the changes in cell abundance and, importantly, cell-specific transcriptional profiles with skeletal muscle aging using scRNAseq. Interestingly, we identified a small population of p16 positive fibro-adipogenic progenitors (FAPs) which, upon further investigation using immunohistochemical methods, were found to express other senescence markers. This subpopulation of FAPs did not exhibit elevation in p21 levels with age. Instead, terminally differentiated myofibers were the source of the p21 increase. Myofibers with high p21 expression exhibit a strong inflammatory phenotype, which includes activated p53 signaling pathways together with strong cytokine-cytokine receptor interactions. We further identified large amounts of cross-talk between different cell types, suggesting that senescent FAPs and myofibers could contribute to skeletal muscle aging in a paracrine manner. Importantly, these observations in mice were confirmed in human samples, suggesting the strong translational power of these findings.

P04.02.A Integrated diagnosis and therapeutic decision of pediatric nervous system tumors using a comprehensive genomic profiling test

Background

Nervous system tumors (NST) are one of the leading causes of cancer-related death in children. Next-generation sequencing has enabled the identification of an increasing number of genetic markers, allowing for a more accurate diagnosis, and may help guide clinicians towards a more specific therapeutic approach.

Material and Methods

Retrospective cohort study of pediatric and young adult patients with NST analyzed with FoundationOneHeme® (FOH) panel from March 2020 to April 2021. This panel was requested, in addition to previously performed pathological reviews and routine genetic tests, in order to obtain more accurate diagnoses and/or possible therapeutic targets.

Results

Fifty NST were analyzed with FOH panel, corresponding to 49 patients. Median age at NST diagnosis was 13 years (range 0-23 years); 50% were females. Initial diagnoses were: 10 pilocytic astrocytomas, 10 diffuse gliomas, 5 ependymomas, 6 mixed neuronal-glial tumors, 7 embryonal tumors, 3 meningeal tumors, 5 peripheral nervous system tumors (PNST) and 4 other types of tumors. There was a change in the final integrated diagnosis after performing the FOH panel in 10 patients (1 pilocytic astrocytoma, 3 diffuse gliomas, 4 mixed neuronal-glial tumors and 1 PNST). In thirty patients, at least one possible therapeutic target was identified: in 5 patients the target therapies are approved for the patients’ tumor type; in 20 patients, target therapies are approved for the same mutations in other tumor types; and in 30 patients target therapies are still being evaluated in ongoing clinical trials. After the results of the FOH panel were known, the previous therapeutic approach was changed in 15 patients, but in only 4 this was attributed to the new genomic findings.

Conclusion

Comprehensive genomic profiling tests can improve diagnostic accuracy and allow for a more reliable approach to the management of pediatric patients with nervous system tumors. Although in most patients there was no immediate therapeutic application of the potential targets found, the genomic data obtained could be very useful to patients who may have tumor progressions in the future.

P11.74.A Plexiform Neurofibromas prevalence and treatment modalities in a referral comprehensive cancer center

Background

Neurofibromatosis type 1 (NF1) is the most common tumor predisposition syndrome, with an incidence of 1/3500. Plexiform neurofibromas (PN) are benign tumors that can occur along the nerve sheath throughout the body, with unpredictable growth and with risk of malignant transformation. Symptoms will depend on their size and location, and include pain, deformity and functional impairment. There is a great variability in the PN severity and impact on quality-of-life (QOL). An unknown percentage of NF1 patients may need treatment, either medical and/or surgical.

Objectives

To assess the frequency of PN in a NF1 population followed in a comprehensive cancer center.

Material and Methods

Retrospective study. All patients with NF1 and PN followed in our center, between 31/12/2000 and 31/12/2021.

Results

Of 438 NF1 patients, 185 had PN (42%). 52 NF1 patients with PN were children (≤ 18). The most common symptoms were pain in 71 people (38,4%), deformity in 70 (37,8%) and functional impairment in 69 (37,3%). Several patients had a combination of these symptoms. Different treatment modalities were used for PN: medical, surgical or both. In this study, 54 patients (29,1%) were treated with MEK inhibitors (selumetinib), 74 patients (40%) were treated surgically and 12,4% (23) needed a combined approach (medical and surgical treatment).

Conclusion

PN are frequent in NF1 patients. A significant percentage is symptomatic and will require treatment, surgical, medical or both. There is no standard of care for PN NF1. The timing and sequence of medical and surgical treatment is yet to be defined.

JS03.5.A Pediatric Neurofibromatosis type 1- associated Malignant Peripheral Nerve Sheath Tumors: a national experience

Background

Malignant peripheral nerve sheath tumors (MPNST) are rare soft tissue sarcomas and although less that 10% occur in the pediatric age, they are the most feared complication in the follow-up of Neurofibromatosis Type 1 (NF1) patients. NF1-children tend to have larger tumors and worse prognosis than non-NF1 patients. There is a lack of data regarding MPNST in pediatric populations with NF1, and the present work aims to characterize a Portuguese population of pediatric NF1 patients who developed a MPNST.

Material and Methods

Retrospective analysis of all NF1-pediatric patients diagnosed with MPNST between 2000 to 2021, from three centers in Portugal. Patient characteristics, treatment modalities and clinical outcomes were reviewed.

Results

12 patients (6 males and 6 females) met the inclusion criteria. 7 had no family history of NF1. Median age at diagnosis was 14.1 years (range 10-18). 5 had been diagnosed previously with Plexiform Neurofibroma and were treated with selumetinib (2) and partial surgery (2). MPNSTs were mostly located in the retroperitoneum (7) and in the proximal lower limbs (2). Only 1 patient had a resectable tumor at diagnosis and 3 patients had metastatic disease. In the FDG-PET scan of evaluated patients (7), the mean maximum standardized uptake value of the main lesion was 6 (range 3.6-9.7).Neoadjuvant ifosfamide plus doxorubicin chemotherapy was used in 4 patients. The median overall survival in this population was 10.3 months (95% CI 0.1-20.6) 2 patients remain alive.

Conclusion

The prognosis of MPNSTs in NF1 pediatric patients is very poor. In a subset of patients, MPNSTs develop from known Plexiform Neurofibromas. Current surveillance ant treatment protocols need to be improved.

Cystlike Lesions as a Late Sequela of Radiotherapy in Pediatric Patients

BACKGROUND AND PURPOSE

The developing nervous system is particularly vulnerable to late adverse effects of cranial radiation therapy, such as leukoencephalopathy, microbleeds, and cavernomas. Cystlike lesions have been rarely described and characterized in the literature. We aimed to characterize cystlike lesions, their risk factors, and association with other late adverse effects.

MATERIALS AND METHODS

Children treated for brain tumors during a 30-year period (n = 139) were included. We documented imaging findings, focusing on cystlike lesion development and its relationship with clinical history and other imaging findings. Multivariable analysis was performed using logistic regression and negative binomial regression models.

RESULTS

Cystlike lesions developed in 16.5% of patients treated with radiotherapy, with a median of 2 years until the development of the first lesion. For every 4-year age increase, there were 50% decreased odds of developing lesions and a 50% decrease in the average count of lesions. Females demonstrated a 4.00 rate ratio of developing a higher number of lesions. Patients who underwent chemoradiotherapy had 3.20 increased odds of developing cystlike lesions compared with patients with radiation therapy alone. A larger proportion of patients treated with methotrexate (25%) developed cystlike lesions, but this was not statistically significant. Cystlike lesions tended to develop in cerebral locations where leukoencephalopathy was worse. A strong relationship was found between the development of cystlike lesions and leukoencephalopathy severity.

CONCLUSIONS

Cystlike lesions are frequent and under-reported late adverse effects of cranial radiation therapy in children. Younger age, chemoradiotherapy, and the severity of leukoencephalopathy represent risk factors for the development of cystlike lesions.

P14.89 What happens after 15 years? A clinical picture of a cohort of survivors of CNS tumors treated with whole-brain irradiation in a National Cancer Center

BACKGROUND

Radiotherapy (RT) is standard curative treatment for many tumours, specially brain tumours. However, RT causes damage to normal brain tissue due to genetic instability, impairment of synaptic plasticity and increased oxidative stress and inflammation. With improved treatment, patient survival also increased in years, making long-term effect of RT more evident. Late toxicities of RT are well described for pediatric survivors but there is scant literature on late toxicities in adult survivors and, in general, the adult brain is considered less susceptible to radiation damage.

MATERIAL AND METHODS

Retrospective analysis of adult patients treated with whole-brain RT with more than 15 years of follow-up. Clinical charts were reviewed to collect clinical, demographic and outcome data.

RESULTS

From 18 patients found (mean age at diagnosis of 27 years, 13 male/ 5 female), 5 were diagnosed with medulloblastoma, 5 CNS lymphoma, 5 with germinoma, 3 with ependymoma and 1 with teratocarcinoma. Most common presentations were headache (61,1%), seizure (16,7%) and dizziness (16,7%). 5 patients (27,8%) had hydrocephalus at diagnosis. All patients received whole-brain RT (mean 40Gys, varying between 21 to 60Gys), alongside with complete surgical resection in 11 patients (61,1%) and chemotherapy in 10 patients (55,6%). Mean follow-up time was 23,6 years and only 1 patient died due to lymphoma recurrence 16,7 years after the initial diagnosis. During follow-up, all patients had late RT induced changes, leukoencephalopathy in 16 patients (88,9%; mean 8,6 years after RT), ischemic stroke in 9 patients (50,0%; mean 16,0 years after RT), cerebral microbleeds in 14 patients (77,8%; mean 15,4 years after RT), cognitive decline in 12 patients (66,7%; mean 15,8 years after RT), radio-induced meningioma in 3 patients (16,7%; mean 18,1 years after RT) and epilepsy in 2 patients (11,1%; mean 10,5 years after RT). Also 1 patient had neurosensorial loss 14,2 years after RT and another one had subarachnoid haemorrhage due to ruptured aneurysm 19 years after RT.

CONCLUSION

Our results show that late RT induced effects are progressive and irreversible in the adult survivors, in a very similar manner as has been reported in the pediatric survivors. The impact on quality of live is increasing as patients survive longer. RT is still an important tool in neuro-oncology, but its role in curing brain tumors needs further study.

JNK/SAPK Signaling Is Essential for Efficient Reprogramming of Human Fibroblasts to Induced Pluripotent Stem Cells

Reprogramming of somatic cells to the phenotypic state termed “induced pluripotency” is thought to occur through three consecutive stages: initiation, maturation, and stabilisation. The initiation phase is stochastic but nevertheless very important as it sets the gene expression pattern that permits completion of reprogramming; hence a better understanding of this phase and how this is regulated may provide the molecular cues for improving the reprogramming process. c‐Jun N‐terminal kinase (JNK)/stress‐activated protein kinase (SAPKs) are stress activated MAPK kinases that play an essential role in several processes known to be important for successful completion of the initiation phase such as cellular proliferation, mesenchymal to epithelial transition (MET) and cell cycle regulation. In view of this, we postulated that manipulation of this pathway would have significant impacts on reprogramming of human fibroblasts to induced pluripotent stem cells. Accordingly, we found that key components of the JNK/SAPK signaling pathway increase expression as early as day 3 of the reprogramming process and continue to rise in reprogrammed cells throughout the initiation and maturation stages. Using both chemical inhibitors and RNA interference of MKK4, MKK7 and JNK1, we tested the role of JNK/SAPK signaling during the initiation stage of neonatal and adult fibroblast reprogramming. These resulted in complete abrogation of fully reprogrammed colonies and the emergence of partially reprogrammed colonies which disaggregated and were lost from culture during the maturation stage. Inhibition of JNK/SAPK signaling resulted in reduced cell proliferation, disruption of MET and loss of the pluripotent phenotype, which either singly or in combination prevented establishment of pluripotent colonies. Together these data provide new evidence for an indispensable role for JNK/SAPK signaling to overcome the well‐established molecular barriers in human somatic cell induced reprogramming. Stem Cells2016;34:1198–1212

HTLV-1 modifies the clinical and immunological response to schistosomiasis

The immunological response in HTLV-1 infected individuals is characterized by a prominent Type-1 cytokine response with high production of IFN-gamma and TNF-alpha. In contrast, helminthic infections and in particular chronic schistosomiasis are associated with a predominant production of IL-4, IL-5, IL-10 and IL-13. Liver fibrosis is the main pathological finding in schistosomiasis that occurs after many years of infection. This pathology is T cell dependent but the immune response mechanisms are not completely understood. The North-east region of Brazil is endemic for both HTLV-1 and schistosomiasis. In the present study the immune response, clinical severity, and therapeutic response to praziquantel of patients with schistosomiasis coinfected with HTLV-1 were compared with patients infected only with S. mansoni. Patients with HTLV-1 and S. mansoni had lower levels of IL-5 (P < 0.05) and higher levels of IFN-gamma (P < 0.05) in cultures stimulated with S. mansoni antigen and decreased S. mansoni antigen specific IgE levels when compared with patients with schistosomiasis without HTLV-1 coinfection. Liver fibrosis was mild in all HTLV-1 coinfected patients and efficacy of praziquantel was lower in patients dually infected than in patients infected only with S. mansoni.