Diagnostic interobserver agreement for thyroid fine-needle aspirates: Effects of reviewer experience and molecular diagnostics.

OBJECTIVES: Few cytologically indeterminate thyroid fine-needle aspirations (FNAs) harbor BRAF V600E. Here, we assess interobserver agreement for The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) category III (atypia of undetermined significance [AUS]) FNAs harboring BRAF V600E and contrast their features with those harboring non-BRAF V600E alterations, with attention to cytopathology experience. METHODS: Seven reviewers evaluated 5 AUS thyroid FNAs harboring BRAF V600E. To blind reviewers, cases were intermixed with 19 FNAs falling within other TBSRTC categories and in which genetic alterations other than BRAF V600E had been identified (24 FNAs total). Interobserver agreement against both "index" and most popular ("mode") diagnoses was calculated. Four additional BRAF V600E cases were independently reviewed. RESULTS: Reviewers included 3 trainees and 3 American Board of Pathology (board)-certified cytopathologists. Board-certified cytopathologists, whose experience ranged from 2 to more than 15 subspecialty practice years, had known AUS rates. BRAF V600E was identified in 5 of 260 (2%) AUS FNAs. Interobserver agreement was higher among cytopathologists with more experience. Mode diagnosis differed from index diagnosis in 6 of 11 cases harboring RAS-like alterations; mode diagnosis was AUS in 4 of 5 BRAF V600E FNAs. CONCLUSIONS: Atypia of undetermined significance of thyroid FNAs harboring BRAF V600E is uncommon yet relatively reproducible, particularly among pathologists with experience. It is advisable to sequence BRAF across V600 in such cases.

Solitary fibrous tumor of deep parotid gland preoperatively classified as salivary gland neoplasm of uncertain malignant potential by the Milan system for reporting salivary gland cytopathology: A common diagnosis for a rare entity.

Solitary fibrous tumor (SFT) is a rare fibroblastic tumor with spindle cell morphology, which is characterized by a prominent branching vasculature and a NAB2-STAT6 gene rearrangement. SFT may occur in any anatomical site and may involve salivary glands, including the parotid gland. We present a young female with a primary parotid SFT diagnosed as "neoplasm-Salivary gland neoplasm of uncertain malignant potential (SUMP)" per the Milan system for reporting salivary gland cytopathology by fine-needle aspiration (FNA) with surgical pathology follow-up. Cytomorphology of SFT is diverse and overlaps with more common entities causing a diagnostic challenge. Non-diagnostic FNA results are not uncommon. Thankfully, the majority of SFTs involving the salivary gland can be identified as "neoplasm" on FNA. The Neoplasm-SUMP subcategory is considered for the majority of cases, which would warrant a diagnostic excision with clear surgical margins, which is also curative in most cases. The Neoplasm-SUMP also perfectly encompasses the neoplastic behavior of SFT, which runs on a scale from indolent to malignant.

Interobserver agreement and risk of malignancy using the International Academy of Cytology Yokohama System for reporting breast FNA biopsy in a liquid-based exclusive cohort.

BACKGROUND: Per the College of American Pathologist's National Breast Fine Needle Aspiration Biopsy (FNAB) Practice Survey, ∼40% of laboratories use liquid-based cytology (LBC) for breast FNAB. The reproducibility of the International Academy of Cytology Yokohama System (YS) for reporting breast FNAB on LBC was explored. DESIGN: Breast FNAB specimens submitted as LBC only (all ThinPrep) between January 2017 and January 2021 were retrieved. Cases without histopathologic follow-up were excluded. Clinical and radiologic information was collected. One cytologist and six cytopathologists rendered diagnoses per YS. All reviewers were blinded to the original diagnosis and histopathologic follow-up. The risk of malignancy was calculated. Concordance rates were calculated by a weighted Cohen Kappa score (κ). RESULTS: Review of 110 cases demonstrated substantial to near-perfect agreement between each reviewer (κ = 0.73-0.91) and follow-up histopathology (κ = 0.66-0.85). The agreement was lowest in the inadequate (κ = 0.05) and atypical (κ = 0.04) categories. The lack of concordance in the atypical category was common in cases with low cellularity or incomplete structural features. The risk of malignancy for inadequate, benign, atypical, suspicious for malignancy, and malignant categories were 12.5% (2/16), 3% (2/65), 67%, (8/12) 100% (1/1), and 100% (16/16). CONCLUSION: Interobserver agreement is excellent using the five YS categories in LBC. Lack of cellularity and incomplete architectural features were barriers to perfect agreement. Established pitfalls in the interpretation of LBC were cause for atypical diagnoses. Continuous training and education are recommended to avoid misdiagnosis because of the nonconventional cytomorphologic features of LBC and to improve inadequate and atypical rates within YS.

Clinical utility of a microRNA classifier in cytologically indeterminate thyroid nodules with RAS mutations: A multi-institutional study.

BACKGROUND: Molecular testing guides the management of cytologically indeterminate thyroid nodules. We evaluated the real-world clinical benefit of a commercially available thyroid mutation panel plus microRNA risk classifier in classifying RAS-mutated nodules. METHODS: We performed a subgroup analysis of the results of molecular testing of Bethesda III/IV nodules using the ThyGenX/ThyGeNEXT-ThyraMIR platform at 3 tertiary-care centers between 2017 and 2021, defining a positive result as 10% or greater risk of malignancy. RESULTS: We identified 387 nodules from 375 patients (70.7% female, median age 59.3 years) who underwent testing. Positive nodules (32.3%) were associated with increased surgical intervention (74.4% vs 14.9%, P < .0001) and carcinoma on surgical pathology (46.4% vs 3.4%, P < .0001) compared to negative modules. RAS mutations were the most common mutations, identified in 71 of 380 (18.7%) nodules, and were classified as ThyraMIR- (28 of 71; 39.4%) or ThyraMIR+ (43 of 71; 60.6%). Among RAS-mutated nodules, there was no significant difference in operative rate (P = .2212) or carcinoma diagnosis (P = .6277) between the ThyraMIR+ and ThyraMIR- groups, and the sensitivity, specificity, negative predictive value, and positive predictive value of ThyraMIR were 64.7%, 34.8%, 40.0%, and 59.5%, respectively. CONCLUSION: Although testing positive is associated with malignancy in surgical pathology, the ThyraMIR classifier failed to differentiate between benign and malignant RAS-mutated nodules. Diagnostic lobectomy should be considered for RAS-mutated nodules, regardless of microRNA expression status.

Use of the Afirma Xpression Atlas for cytologically indeterminate, Afirma Genomic Sequencing Classifier suspicious thyroid nodules: Clinicopathologic analysis with postoperative molecular testing.

OBJECTIVES: Afirma has recently introduced its Xpression Atlas (XA) as an adjunct to its Genomic Sequencing Classifier (GSC) for risk stratification of cytologically indeterminate thyroid nodules. We evaluated the performance of Afirma XA and associated pathologic findings for Afirma GSC suspicious nodules. METHODS: Intradepartmental records of thyroid fine-needle aspirations (FNAs) from January 2021 to December 2022 were identified and reviewed for patient and nodule characteristics, FNA findings, molecular test results, and final surgical pathology, if available. RESULTS: Material for Afirma GSC testing was collected in 624 thyroid FNAs, and 148 (24%) were classified as cytologically indeterminate. Afirma GSC testing was successful in 132 (89%) of those cases, of which 35 (27%) were Afirma GSC suspicious. Afirma XA testing was positive in 11 cases (11/35 [31%]). Eight (73%) patients underwent surgery that revealed 7 patients with papillary thyroid carcinoma and 1 patient with noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) (risk of malignancy: 100% [8/8]). Among the 24 patients with negative Afirma XA results, 19 (79%) underwent surgery, revealing 5 patients with malignancy and 3 patients with NIFTP (risk of malignancy: 42% [8/19]). Overall, the risk of malignancy for Afirma GSC suspicious nodules was 59% (16/27). CONCLUSIONS: Afirma XA improved risk stratification of thyroid disease with a high risk of malignancy in Afirma GSC suspicious nodules. A negative Afirma XA result, however, should not be used as a rule-out test.

Advances and Updates in Parathyroid Pathology.

Hyperparathyroidism is a common endocrine disorder characterized by elevated levels of parathyroid hormone and hypercalcemia and is divided into 3 types: primary, secondary, and tertiary. Distinction between these types is accomplished by correlation of clinical, radiologic, and laboratory findings with pathologic features. Primary hyperparathyroidism occurs sporadically in 85% of cases with the remaining cases associated with multiple familial syndromes. The pathologic manifestations of primary hyperparathyroidism include parathyroid adenoma, parathyroid hyperplasia, and parathyroid carcinoma. Recent advances in the understanding of the pathogenesis of parathyroid disease has helped to refine the diagnosis and classification of parathyroid lesions. The identification of multiple clonal proliferations in traditional multiglandular parathyroid hyperplasia has led to the adoption by the World Health Organization (WHO) of the alternate term of primary hyperparathyroidism-related multiglandular parathyroid disease. Additional nomenclature changes include the adoption of the term atypical parathyroid tumor in lieu of atypical parathyroid adenoma to reflect the uncertain malignant potential of these neoplasms. Clinical and morphologic features characteristic of familial disease have been described that can help the practicing pathologist identify underlying familial disease and provide appropriate management. Use of ancillary immunohistochemistry and molecular studies can be helpful in classifying parathyroid neoplasms. Parafibromin has proven useful as a diagnostic and prognostic marker in atypical parathyroid tumors and parathyroid carcinomas. This review provides an update on the diagnosis and classification of parathyroid lesions considering the recent advances in the understanding of the molecular and clinical features of parathyroid disease and highlights the use of ancillary studies (immunohistochemical, and molecular) to refine the diagnosis of parathyroid lesions.

Now you see me, now you don't: Isolated central nervous system recurrence of CD19-negative diffuse large B-cell lymphoma following CD19-directed CAR T-cell treatment.

The authors discuss a case of CD19-negative diffuse large B-cell lymphoma with central nervous system relapse following CD19-directed CAR T-cell treatment. Absence of CD19 expression by the tumour cells presented a challenge for flow cytometry evaluation.

Evaluating the role of Z-stack to improve the morphologic evaluation of urine cytology whole slide images for high-grade urothelial carcinoma: Results and review of a pilot study.

BACKGROUND: Whole slide imaging (WSI) adoption has been slower in cytopathology due, in part, to challenges in multifocal plane scanning on 3-dimensional cell clusters. ThinPrep and other liquid-based preparations may alleviate the issue by reducing clusters in a concentrated area. This study investigates the use of Z-stacked images for diagnostic assessment and the experience of evaluating urine ThinPrep WSI. METHODS: Thirty ThinPrep urine cases of high-grade urothelial carcinoma (n = 22) and cases of negative for high-grade urothelial carcinoma (n = 8) were included. Slides were scanned at 40× magnification without Z-stack and with Z-stack at 3 layers, 1 µm each. Six cytopathologists and 1 cytotechnologist evaluated the cases in 2 rounds with a 2-week wash-out period in a blinded manner. A Cohen's Kappa (CK) calculated concordance rates. A survey after each round evaluated participant experience. RESULTS: CK with the original report ranged from 0.606 to 1.0 (P < .05) without Z-stack and 0.533 to 1.0 (P < .05) with Z-stack both indicating substantial-to-perfect concordance. For both rounds, interobserver CK was moderate-to-perfect (0.417-1.0, P < .05). Intraobserver CK was 0.697-1.0 (P < 0.05), indicating substantial to perfect concordance. The average scan time and file size for slides without Z-stack and with Z-stack are 6.27 minute/0.827 GB and 14.06 minute/2.650 GB, respectively. Surveys demonstrated a range in comfort and use with slightly more favorable opinions for Z-stacked cases. CONCLUSIONS: Z-stack images provide minimal diagnostic benefit for urine ThinPrep WSI. In addition, Z-stacked urine WSI does not justify the prolonged scan times and larger storage needs compared to those without Z-stack.

Combining molecular testing and the Bethesda category III:VI ratio for thyroid fine-needle aspirates: A quality-assurance metric for evaluating diagnostic performance in a cytopathology laboratory.

BACKGROUND: Molecular testing (MT) of thyroid fine-needle aspiration (FNA)-derived genetic material is commonly used to assess malignancy risk for indeterminate cases. The Bethesda System for Reporting Thyroid Cytopathology (TBS) provides limited guidance for the appropriate use of category III (atypia of undetermined significance [AUS]). The authors combined MT with cytomorphology to monitor AUS diagnoses in a cytopathology laboratory. METHODS: Neoplasia-associated genetic alterations (NGAs) were determined by MT of preoperative FNA biopsies or resected malignancies and were categorized as BRAF V600E mutations, RAS-like mutations (HRAS, NRAS, or KRAS mutations or non-V600E BRAF mutations), or other mutations. RESULTS: Among 7382 thyroid FNA biopsies, the AUS rate was 9.3% overall and ranged from 4.3% to 24.2% among 6 cytopathologists (CPs) who evaluated >150 cases. The ratio of specimens falling into TBS category III to specimens falling into category VI (malignant) (the III:VI ratio) was 2.4 overall (range, 1.1-8.1), and the ratio of specimens falling into TBS categories III and IV (follicular neoplasm or suspicious for follicular neoplasm) combined (III+IV) to specimens falling into category VI (the [III+IV]:VI ratio) was 2.9 overall (range, 1.4-9.5). MT was performed on 588 cases from 560 patients (79% women) with a median age of 56 years (range, 8-89 years). BRAF V600E mutation was the most common (76% of cases) in TBS category VI and was rare (3%) in category III. RAS-like mutations were most common in TBS categories III (13%), IV (25%), and V (suspicious for malignancy) (17.5%). The NGA rate in AUS cases fell between 5% and 20% for 5 of 6 CPs and did not correlate with the III:VI ratio or the (III+IV):VI ratio. CONCLUSIONS: Lack of correlation between the NGA rate and easily calculable diagnostic ratios enables the calibration of diagnostic thresholds, even for CPs who have normal metrics. Specifically, calculation of the NGA rate and the III:VI ratio may allow individual CPs to determine whether they are overcalling or undercalling cases that other CPs might otherwise recategorize.

Root cause analysis of indeterminate diagnoses in serous fluids cytopathology.

INTRODUCTION: The International System for Reporting Serous Fluid Cytopathology proposed five diagnostic categories: Nondiagnostic (ND), Negative for Malignancy (NFM), Atypia of Undetermined Significance (AUS), Suspicious for Malignancy (SFM) and Malignant (MAL) (Primary or Metastatic). The indeterminate (AUS/SFM) categories are challenging for management. The goal of this study is to reveal the root causes contributing to indeterminate diagnoses (ID). MATERIALS AND METHODS: We searched our archives between 1 January 2017 and 30 June 2019, and performed a root cause analysis (RCA) using the "5 whys" method to determine the contributing factors of ID. RESULTS: Nine hundred eleven specimens were evaluated and diagnosed: ND (9, 1%), NFM (667, 73.2%), AUS (51, 5.6%), SFM (27, 3%) and MAL (157, 17.2%). More than one factor contributed to 38/78 ID. Low volume (<50 cc), and low cellularity were identified in 31 and 51 cases, respectively. Three cases were simply deferred to concurrent biopsy. Eleven cases were called atypical, favor reactive mesothelium despite confirmatory IHC. Atypical lymphoid population was reported in seven cases. Cellblocks (CB) were low in cellularity despite volume >1000 mL in 13 cases. Two mesotheliomas were underdiagnosed as suspicious. CONCLUSIONS: Low cellularity and low volume were the most common contributing factors, highlighting the importance of adequate sample collection. Adequate volume specimens with low cellularity may benefit from a close inspection and a second CB. Some IDs can be switched to NFM or MAL with careful consideration of clinical, radiologic findings and ancillary testing, and concurrent surgical pathology correlation when available.

Succinate dehydrogenase-deficient gastrointestinal stromal tumor of stomach diagnosed by endoscopic ultrasound-guided fine-needle biopsy: Report of a distinct subtype in cytology.

Succinate dehydrogenase (SDH)-deficient gastrointestinal stromal tumors (GISTs) are characterized by the lack of mutations in KIT receptor tyrosine kinase complex and platelet derived growth factor receptor-alpha (PDGFRA) that are commonly found in the majority of GISTs. SDH-deficient GISTs comprise approximately 5%-10% of all GISTs. This subset may be associated with Carney Triad and Carney-Stratakis syndrome. SDH-deficient GISTs show unique demographic, radiologic, morphologic findings, clinical behavior, and treatment response. To our knowledge, the identification and characterization of this subset of GISTs have not yet been described in the cytopathology literature. By understanding the clinical as well as the other unique features of this tumor, in addition to the rapidly evolving identification of specific molecular alterations and targeted therapies, cytopathologists may play an important role in the diagnosis and work-up of these patients to allow clinicians to better manage and treat them. We present a young female with gastric SDH-deficient GIST diagnosed by fine-needle biopsy with supporting surgical pathology follow-up and molecular confirmation. This report suggests that the diagnosis of SDH-deficient GIST can be made on cytology in the appropriate clinical setting by using cytomorphologic features and demonstrating SDH loss by IHC on the cell block. In addition, molecular testing may be possible on the cytology cell block or supernatant to confirm the diagnosis.

Nondiagnostic fine-needle aspirates of the pancreas: A root cause analysis.

BACKGROUND: Fine-needle aspiration (FNA) of the pancreas is considered the primary and least invasive diagnostic method in the evaluation of pancreatic lesions. A nondiagnostic sample may trigger repeat FNA or a more invasive diagnostic procedure. The goal of this study was to identify the root causes of nondiagnostic samples. METHODS: We performed a retrospective review of FNAs of the pancreas categorized as nondiagnostic at our institution between 2008 and 2019. Medical records and slides were reviewed to identify the features described by imaging, rapid on-site evaluation, fluid chemistry, final cytology diagnosis, and final histology. A root cause analysis was performed using the Ishikawa (or fishbone) diagram and the 5 Whys method. RESULTS: A total of 30 cases were identified: 11 adenocarcinomas, 6 cases of pancreatitis, 4 intraductal papillary mucinous neoplasms, 3 serous cystadenomas, 3 neuroendocrine tumors, 1 mucinous cystic neoplasm, 1 retention cyst, and 1 case of Brunner gland hyperplasia. The root causes identified were: man in 8 cases, machine in 1 case, method in 17 cases, and material in 18 cases. In many cases, more than 1 root cause contributed to the problem. CONCLUSION: Material related errors contributed to the majority of nondiagnostic results and were primarily related to fibrotic cancers, chronic pancreatitis, absence of diagnostic criteria of cystic lesions, and technically challenging cases. Only 1 major interpretation error was identified. Sampling and interpretive errors contributed equally to man-related causes. For mucinous cysts, neoplastic mucin was difficult to identify in liquid-based preparations. Pathologists tended to issue a nondiagnostic categorization when epithelial cells are lacking and particularly when the nature and radiological impression of the cyst was not communicated.

Tiny but mighty: use of next generation sequencing on discarded cytocentrifuged bile duct brushing specimens to increase sensitivity of cytological diagnosis.

Bile duct brushing (BDB) is used to evaluate pancreatobiliary lesions as it widely samples lesions with a low complication rate. Cytological evaluation of BDB is a specific but insensitive test. There is limited literature on the use of post-cytocentrifuged (PCC) samples, which are usually discarded, for next-generation sequencing (NGS) as an adjunct to cytological diagnosis of BDB. In this study we investigate whether molecular analysis by NGS of PCC specimens improves the sensitivity of diagnosis. PCC samples from 100 consecutive BDB specimens spanning 93 unique patients were retained. DNA was extracted and mutational analysis was performed agnostic of morphologic or clinical findings. Each BDB specimen was characterized as negative, atypical or positive based on morphological analysis by trained cytopathologists. Performance characteristics for mutational profiling and morphological analysis were calculated on the basis of clinicopathologic follow-up. There was sufficient clinicopathologic follow-up to classify 94 of 100 cases as either malignant (n = 43) or benign (n = 51). Based on morphologic analysis of cytology, these 94 cases were classified as either benign (n = 55), atypical (n = 18), or as at least suspicious or positive for malignancy (n = 21). Morphologic analysis of cytology showed a sensitivity of 49% and a specificity of 100% if atypical cases were considered negative. NGS revealed oncogenic alterations in 40/43 (93%) of malignant cases based on clinicopathologic follow-up. The most common alterations were in KRAS and TP53, observed in 77% and 49% of malignant cases respectively. No alterations were observed in the 51 benign cases classified based on clinicopathologic follow-up. Supplementing cytomorphologic analysis with molecular profiling of PCC by targeted NGS analysis increased the sensitivity to 93% and maintained specificity at 100%. This study provides evidence for the utility of NGS molecular profiling of PCC specimens to increase the sensitivity of BDB cytology samples, although studies with larger cohorts are needed to verify these findings.

Biallelic PTCH1 Inactivation Is a Dominant Genomic Change in Sporadic Keratocystic Odontogenic Tumors.

Keratocystic odontogenic tumors (KCOTs) are locally aggressive odontogenic neoplasms with recurrence rates of up to 60%. Approximately 5% of KCOTs are associated with nevoid basal cell carcinoma (Gorlin) syndrome and 90% of these show genomic inactivation of the PTCH1 gene encoding Patched 1. Sporadic KCOTs reportedly have PTCH1 mutations in 30% of cases, but previous genomic analyses have been limited by low tumor DNA yield. The aim of this study was to identify recurrent genomic aberrations in sporadic KCOTs using a next-generation sequencing panel with complete exonic coverage of sonic hedgehog (SHH) pathway members PTCH1, SMO, SUFU, GLI1, and GLI2. Included were 44 sporadic KCOTs from 23 female and 21 male patients with a median age of 50 years (range, 10 to 82 y) and located in the mandible (N=33) or maxilla (N=11). Sequencing identified PTCH1 inactivating mutations in 41/44 (93%) cases, with biallelic inactivation in 35 (80%) cases; 9q copy neutral loss of heterozygosity targeting the PTCH1 locus was identified in 15 (34%) cases. No genomic aberrations were identified in other sequenced SHH pathway members. In summary, we demonstrate PTCH1 inactivating mutations in 93% of sporadic KCOTs, indicating that SHH pathway alterations are a near-universal event in these benign but locally aggressive neoplasms. The high frequency of complete PTCH1 loss of function may provide a rational target for SHH pathway inhibitors to be explored in future studies.

Association of Bacterial Vaginosis and Human Papilloma Virus Infection With Cervical Squamous Intraepithelial Lesions.

OBJECTIVES: Human papillomavirus (HPV) is known to be associated with squamous intraepithelial lesions (SILs). However, there is limited and conflicting literature on the relationship between bacterial vaginosis (BV) and SIL. The aim of this study is to determine the prevalence of BV and evaluate the association between BV and SIL. METHODS: A retrospective study was performed on 10,546 cases between 2012 and 2017. HPV results were available in 7,081 cases. RESULTS: BV was present in 17.6% of cases. There was significant association between BV, positive HPV infection, and high-grade SIL. BV patients with negative HPV infection showed more squamous abnormalities than BV-negative HPV-negative patients. CONCLUSIONS: We found there is a significant association between BV and SIL. BV is more common among patients with HPV infection and is independently associated with squamous abnormalities in cervical smears and surgical follow-up.

Cyclin A2 promotes DNA repair in the brain during both development and aging.

Various stem cell niches of the brain have differential requirements for Cyclin A2. Cyclin A2 loss results in marked cerebellar dysmorphia, whereas forebrain growth is retarded during early embryonic development yet achieves normal size at birth. To understand the differential requirements of distinct brain regions for Cyclin A2, we utilized neuroanatomical, transgenic mouse, and mathematical modeling techniques to generate testable hypotheses that provide insight into how Cyclin A2 loss results in compensatory forebrain growth during late embryonic development. Using unbiased measurements of the forebrain stem cell niche, we parameterized a mathematical model whereby logistic growth instructs progenitor cells as to the cell-types of their progeny. Our data was consistent with prior findings that progenitors proliferate along an auto-inhibitory growth curve. The growth retardation inCCNA2-null brains corresponded to cell cycle lengthening, imposing a developmental delay. We hypothesized that Cyclin A2 regulates DNA repair and that CCNA2-null progenitors thus experienced lengthened cell cycle. We demonstrate that CCNA2-null progenitors suffer abnormal DNA repair, and implicate Cyclin A2 in double-strand break repair. Cyclin A2's DNA repair functions are conserved among cell lines, neural progenitors, and hippocampal neurons. We further demonstrate that neuronal CCNA2 ablation results in learning and memory deficits in aged mice.

Area postrema undergoes dynamic postnatal changes in mice and humans.

The postnatal period in mammals represents a developmental epoch of significant change in the autonomic nervous system (ANS). This study focuses on postnatal development of the area postrema, a crucial ANS structure that regulates temperature, breathing, and satiety, among other activities. We find that the human area postrema undergoes significant developmental changes during postnatal development. To characterize these changes further, we used transgenic mouse reagents to delineate neuronal circuitry. We discovered that, although a well-formed ANS scaffold exists early in embryonic development, the area postrema shows a delayed maturation. Specifically, postnatal days 0-7 in mice show no significant change in area postrema volume or synaptic input from PHOX2B-derived neurons. In contrast, postnatal days 7-20 show a significant increase in volume and synaptic input from PHOX2B-derived neurons. We conclude that key ANS structures show unexpected dynamic developmental changes during postnatal development. These data provide a basis for understanding ANS dysfunction and disease predisposition in premature and postnatal humans.

Deterministic transfection drives efficient nonviral reprogramming and uncovers reprogramming barriers.

Safety concerns and/or the stochastic nature of current transduction approaches have hampered nuclear reprogramming's clinical translation. We report a novel non-viral nanotechnology-based platform permitting deterministic large-scale transfection with single-cell resolution. The superior capabilities of our technology are demonstrated by modification of the well-established direct neuronal reprogramming paradigm using overexpression of the transcription factors Brn2, Ascl1, and Myt1l (BAM). Reprogramming efficiencies were comparable to viral methodologies (up to ~9-12%) without the constraints of capsid size and with the ability to control plasmid dosage, in addition to showing superior performance relative to existing non-viral methods. Furthermore, increased neuronal complexity could be tailored by varying BAM ratio and by including additional proneural genes to the BAM cocktail. Furthermore, high-throughput NEP allowed easy interrogation of the reprogramming process. We discovered that BAM-mediated reprogramming is regulated by AsclI dosage, the S-phase cyclin CCNA2, and that some induced neurons passed through a nestin-positive cell stage. FROM THE CLINICAL EDITOR: In the field of regenerative medicine, the ability to direct cell fate by nuclear reprogramming is an important facet in terms of clinical application. In this article, the authors described their novel technique of cell reprogramming through overexpression of the transcription factors Brn2, Ascl1, and Myt1l (BAM) by in situ electroporation through nanochannels. This new technique could provide a platform for further future designs.