Cranium growth, patterning and homeostasis.

Craniofacial development requires precise spatiotemporal regulation of multiple signaling pathways that crosstalk to coordinate the growth and patterning of the skull with surrounding tissues. Recent insights into these signaling pathways and previously uncharacterized progenitor cell populations have refined our understanding of skull patterning, bone mineralization and tissue homeostasis. Here, we touch upon classical studies and recent advances with an emphasis on developmental and signaling mechanisms that regulate the osteoblast lineage for the calvaria, which forms the roof of the skull. We highlight studies that illustrate the roles of osteoprogenitor cells and cranial suture-derived stem cells for proper calvarial growth and homeostasis. We also discuss genes and signaling pathways that control suture patency and highlight how perturbing the molecular regulation of these pathways leads to craniosynostosis. Finally, we discuss the recently discovered tissue and signaling interactions that integrate skull and cerebrovascular development, and the potential implications for both cerebrospinal fluid hydrodynamics and brain waste clearance in craniosynostosis.

A precision neuroscience approach to estimating reliability of neural responses during emotion processing: Implications for task-fMRI.

Recent work demonstrating low test-retest reliability of neural activation during fMRI tasks raises questions about the utility of task-based fMRI for the study of individual variation in brain function. Two possible sources of the instability in task-based BOLD signal over time are noise or measurement error in the instrument, and meaningful variation across time within-individuals in the construct itself-brain activation elicited during fMRI tasks. Examining the contribution of these two sources of test-retest unreliability in task-evoked brain activity has far-reaching implications for cognitive neuroscience. If test-retest reliability largely reflects measurement error, it suggests that task-based fMRI has little utility in the study of either inter- or intra-individual differences. On the other hand, if task-evoked BOLD signal varies meaningfully over time, it would suggest that this tool may yet be well suited to studying intraindividual variation. We parse these sources of variance in BOLD signal in response to emotional cues over time and within-individuals in a longitudinal sample with 10 monthly fMRI scans. Test-retest reliability was low, reflecting a lack of stability in between-person differences across scans. In contrast, within-person, within-session internal consistency of the BOLD signal was higher, and within-person fluctuations across sessions explained almost half the variance in voxel-level neural responses. Additionally, monthly fluctuations in neural response to emotional cues were associated with intraindividual variation in mood, sleep, and exposure to stressors. Rather than reflecting trait-like differences across people, neural responses to emotional cues may be more reflective of intraindividual variation over time. These patterns suggest that task-based fMRI may be able to contribute to the study of individual variation in brain function if more attention is given to within-individual variation approaches, psychometrics-beginning with improving reliability beyond the modest estimates observed here, and the validity of task fMRI beyond the suggestive associations reported here.

The biomechanics of chewing and suckling in the infant: A potential mechanism for physiologic metopic suture closure.

Craniosynostosis is a condition with neurologic and aesthetic sequelae requiring invasive surgery. Understanding its pathobiology requires familiarity with the processes underlying physiologic suture closure. Animal studies have shown that cyclical strain from chewing and suckling influences the closure of cranial vault sutures, especially the metopic, an important locus of craniosynostosis. However, there are no human data correlating strain patterns during chewing and suckling with the physiologically early closure pattern of the metopic suture. Furthermore, differences in craniofacial morphology make it challenging to directly extrapolate animal findings to humans. Eight finite-element analysis (FEA) models were built from craniofacial computer tomography (CT) scans at varying stages of metopic suture closure, including two with isolated non-syndromic metopic craniosynostosis. Muscle forces acting on the cranium during chewing and suckling were simulated using subject-specific jaw muscle cross-sectional areas. Chewing and suckling induced tension at the metopic and sagittal sutures, and compressed the coronal, lambdoid, and squamous sutures. Relative to other cranial vault sutures, the metopic suture experienced larger magnitudes of axial strain across the suture and a lower magnitude of shear strain. Strain across the metopic suture decreased during suture closure, but other sutures were unaffected. Strain patterns along the metopic suture mirrored the anterior to posterior sequence of closure: strain magnitudes were highest at the glabella and decreased posteriorly, with minima at the nasion and the anterior fontanelle. In models of physiologic suture closure, increased degree of metopic suture closure correlated with higher maximum principal strains across the frontal bone and mid-face, a strain regime not observed in models of severe metopic craniosynostosis. In summary, our work provides human evidence that bone strain patterns from chewing and suckling correlate with the physiologically early closure pattern of the metopic suture, and that deviations from physiologic strain regimes may contribute to clinically observed craniofacial dysmorphism.

OUHP: an optimized universal hairpin primer system for cost-effective and high-throughput RT-qPCR-based quantification of microRNA (miRNA) expression.

MicroRNAs (miRNAs or miRs) are single-stranded, ∼22-nucleotide noncoding RNAs that regulate many cellular processes. While numerous miRNA quantification technologies are available, a recent analysis of 12 commercial platforms revealed high variations in reproducibility, sensitivity, accuracy, specificity and concordance within and/or between platforms. Here, we developed a universal hairpin primer (UHP) system that negates the use of miRNA-specific hairpin primers (MsHPs) for quantitative reverse transcription PCR (RT-qPCR)-based miRNA quantification. Specifically, we analyzed four UHPs that share the same hairpin structure but are anchored with two, three, four and six degenerate nucleotides at 3'-ends (namely UHP2, UHP3, UHP4 and UHP6), and found that the four UHPs yielded robust RT products and quantified miRNAs with high efficiency. UHP-based RT-qPCR miRNA quantification was not affected by long transcripts. By analyzing 14 miRNAs, we demonstrated that UHP4 closely mimicked MsHPs in miRNA quantification. Fine-tuning experiments identified an optimized UHP (OUHP) mix with a molar composition of UHP2:UHP4:UHP6 = 8:1:1, which closely recapitulated MsHPs in miRNA quantification. Using synthetic LET7 isomiRs, we demonstrated that the OUHP-based qPCR system exhibited high specificity and sensitivity. Collectively, our results demonstrate that the OUHP system can serve as a reliable and cost-effective surrogate of MsHPs for RT-qPCR-based miRNA quantification for basic research and precision medicine.

Simultaneous Coronoid Bone Grafting in Ballistic Facial Trauma Patients Undergoing Coronoidectomy.

Ballistic facial trauma can cause complex fractures and overlying soft tissue damage, with a zone of injury that extends beyond the bullet tract. Early skeletal fixation is indicated, and previous large case series describe the use of debrided bone fragments as 'spare part' grafts. This series presents the indications and techniques for simultaneous coronoid bone grafting in 2 patients who sustained a gunshot wound to the right midface and required coronoidectomy. The coronoid process was used as (1) an interposition graft in the lateral buttress of the right maxilla for stability, and (2) an onlay graft on the right inferior orbital rim for contour. Both patients did not have graft infection, extrusion, or malposition at the 1-month clinic follow-up. The coronoid process of the mandible is a viable, safe spare-part option, despite the possible location of the coronoid process within the zone of injury in the reconstruction of complex ballistic facial trauma.

The Role of Digital Surgical Planning and Surgical Guides in the Treatment of Unilateral Condylar Hyperplasia.

Unilateral condylar hyperplasia (UCH) results in facial asymmetry, malocclusion, and temporomandibular joint dysfunction. Treatment consists of both surgical and orthodontic intervention. A review was performed for 4 patients with UCH who underwent digital surgical planning (DSP)-assisted condylectomy. All patients were female, aged 14 to 35 years at the time of operation with facial asymmetry and class III malocclusion. None of the patients had prior treatment and all had perioperative orthodontic appliances to provide fixation and postoperative elastic therapy. All patients underwent DSP-guided condylectomy, and intraoperative surgical cutting guides were used for 3 of the patients. All had significant improvement in facial symmetry and occlusion. None had recurrence, and additional intervention has not been required. If UCH is recognized before marked secondary changes in the maxilla, mandible, and occlusion, future orthognathic surgery may be potentially obviated. Craniomaxillofacial surgeons should consider using DSP and surgical guides in the treatment of UCH.

Pyrvinium doubles against WNT-driven cancer.

The WNT-ß-catenin signaling pathway has a major role in regulating cell proliferation and differentiation. Aberrant activation of the pathway contributes to various human cancer types. Because casein kinase CK1α-initiated phosphorylation of ß-catenin is a key first step to restrain WNT signaling, effective restoration of CK1α activity represents an innovative strategy to combat WNT-driven cancer. A recent study in JBC reveals the anthelmintic pyrvinium directly binds to CK1α as an activator and also stabilizes CK1α protein, doubling against WNT-driven cancer activity.

Lower implicit self-esteem as a pathway linking childhood abuse to depression and suicidal ideation.

Identifying the potential pathways linking childhood abuse to depression and suicidal ideation is critical for developing effective interventions. This study investigated implicit self-esteem-unconscious valenced self-evaluation-as a potential pathway linking childhood abuse with depression and suicidal ideation. A sample of youth aged 8-16 years (N = 240) completed a self-esteem Implicit Association Test (IAT) and assessments of abuse exposure, and psychopathology symptoms, including depression, suicidal ideation, anxiety, and externalizing symptoms. Psychopathology symptoms were re-assessed 1-3 years later. Childhood abuse was positively associated with baseline and follow-up depression symptoms and suicidal ideation severity, and negatively associated with implicit self-esteem. Lower implicit self-esteem was associated with both depression and suicidal ideation assessed concurrently and predicted significant increases in depression and suicidal ideation over the longitudinal follow-up period. Lower implicit self-esteem was also associated with baseline anxiety, externalizing symptoms, and a general psychopathology factor (i.e. p-factor). We found an indirect effect of childhood abuse on baseline and follow-up depression symptoms and baseline suicidal ideation through implicit self-esteem. These findings point to implicit self-esteem as a potential mechanism linking childhood abuse to depression and suicidal ideation.

Plastic Surgery Away Rotations During the Coronavirus Disease Pandemic: A Virtual Experience.

BACKGROUND: Plastic surgery has traditionally been a specialty that places a strong emphasis on away rotations during the final year of medical school. These rotations allow the program and residency candidates to become better acquainted and are often crucial, as a large portion of applicants match at programs where they rotated. The coronavirus disease 2019 (COVID-19) pandemic forced many institutions to modify their educational curriculums when away rotations were canceled. We present our experience creating and implementing a virtual plastic surgery rotation. METHODS: Our virtual program was designed to mirror the in-person away rotations as much as possible. Prerotation and postrotation surveys from the students as well as feedback interviews with the students, residents, and faculty were used to gather information on the experience. RESULTS: We created a 2-week curriculum including approximately 20 hours of lecture time, 28 hours of operating room time, 2.5 hours of one-on-one mentorship, and 3 hours of social opportunities. Students reported that they learned more about plastic surgery and the residency program, but in contrast to this, some found it difficult to make an impression. CONCLUSIONS: We developed a novel 2-week virtual curriculum that provided visiting medical students from across the country an opportunity to learn more about plastic surgery and our residency program. Virtual learning is becoming a vital part of education, and our study provides pearls and pitfalls when structuring these experiences.

Impact of Cleft Palate on Tongue-Based Upper Airway Obstruction in Pierre Robin Sequence: Implications for Mandibular Distraction Osteogenesis and Timing of Cleft Palate Repair.

INTRODUCTION: The objectives of this study are to analyze the impact of cleft palate (CP) on upper airway obstruction using polysomnography in patients with Pierre Robin Sequence (PRS) undergoing mandibular distraction osteogenesis (MDO) and subsequent CP repair. METHODS: A single-surgeon, retrospective chart review was performed of all patients with nonsyndromic PRS treated with MDO. Severity of upper airway obstruction was evaluated pre- and post-distraction via polysomnography. Details of MDO and CP repair were collected and any complications recorded. RESULTS: Twenty-one nonsyndromic PRS patients with CP and 6 patients without CP met inclusion criteria. There was no significant difference in predistraction apnea-hypopnea index between the 2 groups (53.4 ±â€Š42.1 versus 34.4 ±â€Š18.9; P = 0.3). Patients with CP had significantly higher predistraction SpO2 saturation (94.5 ±â€Š1.6% versus 91.0% ±â€Š4.8%; P = 0.01), SpO2 nadir (74.5% ±â€Š9.1% versus 63.6% ±â€Š11.6%; P = 0.03) and lower percentage time spent below 90% SpO2 (6.0% ±â€Š7.2% versus 23.6% ±â€Š29.9%; P = 0.04). The rate of oronasal fistulas formation was 38%. The time between MDO and CP repair was shorter for patients with complications (250.8 ±â€Š3.3 versus 370.8 ±â€Š191.9 days; P = 0.08). Five patients experienced relapse of respiratory difficulties after CP repair. CONCLUSIONS: The presence of CP in nonsyndromic PRS patients decreases the severity of obstructive sleep apnea by oxygen parameters on PSG. Palatal fistulas and relapse of respiratory distress are common complications of CP repair following MDO. Delaying CP repair may help to decrease complication rates.

BMP9-initiated osteogenic/odontogenic differentiation of mouse tooth germ mesenchymal cells (TGMCS) requires Wnt/ß-catenin signalling activity.

Teeth arise from the tooth germ through sequential and reciprocal interactions between immature epithelium and mesenchyme during development. However, the detailed mechanism underlying tooth development from tooth germ mesenchymal cells (TGMCs) remains to be fully understood. Here, we investigate the role of Wnt/ß-catenin signalling in BMP9-induced osteogenic/odontogenic differentiation of TGMCs. We first established the reversibly immortalized TGMCs (iTGMCs) derived from young mouse mandibular molar tooth germs using a retroviral vector expressing SV40 T antigen flanked with the FRT sites. We demonstrated that BMP9 effectively induced expression of osteogenic markers alkaline phosphatase, collagen A1 and osteocalcin in iTGMCs, as well as in vitro matrix mineralization, which could be remarkably blunted by knocking down ß-catenin expression. In vivo implantation assay revealed that while BMP9-stimulated iTGMCs induced robust formation of ectopic bone, knocking down ß-catenin expression in iTGMCs remarkably diminished BMP9-initiated osteogenic/odontogenic differentiation potential of these cells. Taken together, these discoveries strongly demonstrate that reversibly immortalized iTGMCs retained osteogenic/odontogenic ability upon BMP9 stimulation, but this process required the participation of canonical Wnt signalling both in vitro and in vivo. Therefore, BMP9 has a potential to be applied as an efficacious bio-factor in osteo/odontogenic regeneration and tooth engineering. Furthermore, the iTGMCs may serve as an important resource for translational studies in tooth tissue engineering.

The Pediatric Craniofacial Collaborative Group (PCCG) Consensus Conference Methodology.

OBJECTIVE: This article describes the methodology used for the Pediatric Craniofacial Collaborative Group (PCCG) Consensus Conference. DESIGN: This is a novel Consensus Conference of national experts in Pediatric Craniofacial Surgery and Anesthesia, who will follow standards set by the Institute of Medicine and using the Research and Development/University of California, Los Angeles appropriateness method, modeled after the Pediatric Critical Care Transfusion and Anemia Expertise Initiative. Topics related to pediatric craniofacial anesthesia for open cranial vault surgery were divided into twelve subgroups with a systematic review of the literature. SETTING: A group of 20 content experts met virtually between 2019 and 2020 and will collaborate in their selected topics related to perioperative management for pediatric open cranial vault surgery for craniosynostosis. These groups will also identify where future research is needed. CONCLUSIONS: Experts in pediatric craniofacial surgery and anesthesiology are developing recommendations on behalf of the Pediatric Craniofacial Collaborative Group for perioperative management of patients undergoing open cranial vault surgery for craniosynostosis and identifying future research priorities.

Facial Suture Pathology in Syndromic Craniosynostosis: Human and Animal Studies.

BACKGROUND: Facial deformities in syndromic craniosynostosis are not only functionally, psychosocially, and aesthetically impairing but also notoriously challenging to reconstruct. Whether facial suture synostosis plays a significant role in the pathogenesis of these deformities is inadequately studied in human patients. METHODS: The MEDLINE database was queried using a methodologically generated search term inventory. Article inclusion was adjudicated by 2 authors after independent review. Articles provided insight into facial suture involvement in either syndromic craniosynostosis patients or animal models of disease. RESULTS: Comprehensive review yielded 19 relevant articles meeting inclusion criteria. Mid-20th century craniofacial biologists characterized how patent facial sutures are essential for normal postnatal facial development. They also posited that premature ossification disrupts growth vectors, causing significant dysmorphologies. Recently, facial suture synostosis was found to cause midfacial deformities independent of cranial base pathology in mouse models of syndromic craniosynostosis. Few recent studies have begun exploring facial suture involvement in patients, and although they have paved the way for future research, they bear significant limitations. CONCLUSIONS: The hypothesis that facial suture synostosis acts in conjunction with cranial base pathology to produce the prominent, multifocal facial deformities in syndromic craniosynostosis may fundamentally alter surgical management and warrants further investigation. Methodically evaluating the literature, this review synthesizes all basic science and human clinical research thus far on the role of facial sutures in syndromic craniosynostosis and elucidates important topics for future research. We ultimately identify the need for rigorous imaging studies that longitudinally evaluate facial osteology across patients with various craniosynostosis syndromes.

A Novel Approach to Coronoidectomy: the Modified Keen Technique.

INTRODUCTION: Coronoid fractures are relatively rare fractures of the craniofacial skeleton, but typically occur concomitantly with high-velocity craniofacial trauma to the midface and lateral mandible. Management of coronoid fractures may vary, but when surgical excision is indicated, treatment frequently involves an intraoral approach through a posterior intraoral incision along the mandibular ramus. Here, the authors present an alternative and novel approach to the coronoid process based on the Keen approach to the lateral midface. TECHNICAL NOTE: The authors present a patient with a left zygomatico-maxillary complex fracture and left coronoid fracture. After disimpaction of the zygomatico-maxillary complex fracture, a maxillary vestibular incision in the gingivobuccal sulcus was made. After subperiosteal dissection, the maxillary fracture was exposed and fixated. A modified Keen approach was used to expose the coronoid process, perform temporalis myotomy, and excise the fracture fragment. DISCUSSION: Compared to the classic intraoral approach to coronoidectomy, the modified Keen approach is a quick, versatile technique that allows for direct visualization of the coronoid process without the use of endoscopy, facilitates fixation of concurrent midfacial fractures, and utilizes an anterior intraoral incision that is easy to retract and close. For these reasons, the modified Keen technique for coronoidectomy should be considered in the treatment of trismus when an intraoral approach is indicated.

Predictors of Opioid Prescription After Orthognathic Surgery in Opioid Naive Adults From a Large Database.

BACKGROUND: Orthognathic surgery often requires postoperative opioid pain management. The goal of this study was to examine opioid prescribing patterns in adults after orthognathic surgery and to analyze factors associated with high-dose postoperative opioid administration and persistent opioid use. METHODS: We included opioid naive adults in the IBM MarketScan Databases who had undergone orthognathic surgery from 2003 to 2017. Three outcomes were examined: presence of a perioperative outpatient opioid claim; total oral morphine milliequivalents (MMEs) in the perioperative period; and persistent opioid use. Univariate analysis and multiple regression were used to determine associations between the outcomes and independent variables. RESULTS: Our study yielded a cohort of 8163 opioid naive adults, 45.6% of whom had an opioid claim in the perioperative period. The average prescribed MMEs in the perioperative period was 466 MMEs total, and 66 MMEs daily. Of patients with an opioid claim, 17.9% had persistent opioid use past 90 days. The presence of a complication was a predictor of having an opioid claim (P<0.001). Increasing age (P<0.001) and days hospitalized (P < 0.001) were associated with increased opioid usage. Persistent opioid use was associated with being prescribed more than 600 MMEs in the perioperative period (P < 0.001), as well as increasing age and days hospitalized. Interestingly, patients undergoing double-jaw surgery did not have significantly more opioids prescribed than those undergoing single-jaw surgery. CONCLUSIONS: Prescription opioids are relatively uncommon after jaw surgery, although 17.9% of patients continue to use opioids beyond 3 months after surgery. Predictors of persistent opioid use in this population include the number of days hospitalized, increasing age, and increasing amount of opioid prescribed postoperatively.

Skin Deep: Perception of Scars After Cranial Vault Reconstruction.

PURPOSE: Children with craniosynostosis are vulnerable to stigmatization and social withdrawal. Cranial vault reconstruction (CVR) results in large bicoronal scars, which may trigger further insult to self-esteem and social outcasting. This study aimed to delineate determinants of patient scar self-consciousness, parental scar satisfaction, and parent satisfaction with their child's overall medical/surgical care. METHODS: A 14-item questionnaire was distributed to parents of 95 patients who underwent open CVR at our institution. Age at first surgery, race, hair type, typical style, number of surgeries, complications, and use of distractors were surveyed. Patient scar self-consciousness, parental scar satisfaction, and parent satisfaction with their child's overall medical/surgical care were also queried. T tests and linear regressions were performed for binary and continuous variables, respectively. RESULTS: Of 45 respondents, significant associations were found between: (1) complications and decreased parent scar satisfaction; (2) complications and decreased overall satisfaction with medical/surgical care, and (3) older age at time of initial surgery and decreased overall medical/surgical satisfaction. A significant association was found between parental scar satisfaction and overall medical/surgical satisfaction (ß = 0.65, P = .002). There was no significant association between parent scar satisfaction and parental-reported patient self-consciousness, or parental-reported patient self-consciousness and overall medical/surgical satisfaction. CONCLUSIONS: Our results underscore the value of scar aesthetics in reconstructive goals. Advanced age and complications are important determinants of satisfaction. However, the lack of association between parent-reported patient self-consciousness and parental scar satisfaction suggests differences in aesthetic priorities between parents and children. Further studies may elucidate additional aesthetic considerations of CVR in ethnic/racial minorities.

Evaluating the Effects of COVID-19 on Plastic Surgery Emergencies: Protocols and Analysis From a Level I Trauma Center.

BACKGROUND: The COVID-19 crisis has brought many unique challenges to the health care system. Across the United States, social distancing measures have been put in place, including stay-at-home (SAH) orders, to combat the spread of this infection. This has impacted the type and volume of traumatic injuries sustained during this time. Meanwhile, steps have been taken in our health care system to assure that adequate resources are available to maintain a high standard of patient care while recognizing the importance of protecting health care providers. Using comparative data, we aim to describe the trends in traumatic injuries managed by our plastic surgery service and detail the changes in consultation policies made to minimize provider exposure. METHODS: A retrospective chart review was performed of all plastic surgery emergencies at our institution during the 3 weeks preceding the issuance of SAH orders in Chicago and the 3 weeks after. The electronic medical record was queried for patient age, type and mechanism of injury, location where injury was sustained, presence of domestic violence, length of inpatient hospital stays, and treatment rendered. The two 3-week periods were then comparatively analyzed to determine differences and trends in these variables and treatment rendered. The 2 periods were then comparatively analyzed to determine differences and trends in these variables. RESULTS: There was a significant decrease in trauma consults since the issuance of SAH (88 pre-SAH vs 62 post-SAH) with a marked decrease in trauma-related hand injuries. There was an increase in the percentage of assault-related injuries including those associated with domestic violence, whereas there was an overall decrease in motor vehicle collisions. There was no notable change in the location where injuries were sustained. Significantly fewer patients were seen by house staff in the emergency room, whereas those requiring surgical intervention were able to receive care without delay. CONCLUSIONS: Stay-at-home orders in Chicago have impacted traumatic injury patterns seen by the Section of Plastic and Reconstructive Surgery at a level I Trauma Center. Safe and timely care can continue to be provided with thorough communication, vigilance, and guidance from our colleagues.

Custom Alloplastic Temporomandibular Joint Reconstruction: Expanding Reconstructive Horizons.

Custom alloplastic temporomandibular joint (TMJ) reconstruction has been well established for the management of end-stage TMJ disease. However, its use in congenital TMJ deformities is limited. Here, the authors present initial outcomes of skeletally mature patients who underwent custom alloplastic TMJ reconstruction and simultaneous orthognathic surgery.A retrospective case series of patients who underwent custom alloplastic TMJ reconstruction concurrent with orthognathic surgery between 2014 and 2019 was completed. Functional, aesthetic and orthodontic outcomes as well as complications were recorded.Seven TMJs in 5 skeletally mature patients (4 female, 1 male, ages 16-30) (2 bilateral, 3 unilateral) were replaced. All but 1 patient had previous attempts at reconstructive surgery with poor results. All cases were prepared using virtual surgical planning and underwent concomitant maxillomandibular orthognathic surgery. All patients demonstrated improved post-operative occlusions. Four of 5 patients achieved >30 millimeters of post-operative MIO. Complications included ear canal perforation and facial nerve dysfunction.There were no infections or other implant-related complications. Mean follow up was 2 years and 15 days. Alloplastic TMJ reconstruction at the time of skeletal maturity for patients with congenital mandibular TMJ defects is an alternative to existing management options. Further long-term prospective outcomes studies are ongoing.

Airway Morphological Changes in Pierre Robin Sequence: A Retrospective Study.

OBJECTIVE: To investigate airway morphology changes in patients with Pierre Robin sequence (PRS) pre-/post-mandibular distraction osteogenesis (MDO) and to compare morphologic changes to age-matched controls. DESIGN: Retrospective case-control study. SETTING: Urban, academic, tertiary medical center. PATIENTS, PARTICIPANTS: Fifteen patients with PRS after MDO to relieve upper airway obstruction (UAO) (2008-2018); age-matched controls for post-MDO patients. INTERVENTIONS: Mandibular distraction osteogenesis, curvilinear internal mandibular distractors. MAIN OUTCOME MEASURES: (1) Physiologic improvement after MDO (apnea-hypopnea index; minimum oxygen saturation); (2) airway size (volume, surface area, length, mean/minimum cross-sectional area), shape (lateral:anterior-posterior ratio, cross-sectional area ratios, uniformity, sphericity), and changes with MDO; and (3) post-MDO airway size, shape versus age-matched controls. RESULTS: Airway size increased after MDO (volume, P = .01; surface area, P = .02; length, P = .01), as did cross-sectional area (mean, P = .02; minimum, P = .02; minimum retropalatal, P = .05, mid-retroglossal, P = .02). Post-MDO PRS airways were larger than controls (volume, P < .01; surface area, P < .01; length, P < .01, cross-sectional area, P = .03). Airway shape remained nonuniform and flat post-MDO; control airways were round. Two syndromic patients required repeat MDO and had subphysiologic post-MDO airway cross-sectional area. Post-MDO PRS patients with supraphysiologic cross-sectional area along the entire airway had no UAO recurrence. CONCLUSIONS: In this small, heterogenous patient sample, MDO increases airway size, may preferentially affect the retropalatal airway, and often results in supraphysiologic airway dimensions. These retropalatal changes may be important in relieving severe UAO in patients with PRS. Generalizability of our results is limited by small cohort size and patient heterogeneity.

BMP9-induced osteoblastic differentiation requires functional Notch signaling in mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are multipotent progenitors that can differentiate into multiple lineages including osteoblastic lineage. Osteogenic differentiation of MSCs is a cascade that recapitulates most, if not all, of the molecular events occurring during embryonic skeletal development, which is regulated by numerous signaling pathways including bone morphogenetic proteins (BMPs). Through a comprehensive analysis of the osteogenic activity, we previously demonstrated that BMP9 is the most potent BMP for inducing bone formation from MSCs both in vitro and in vivo. However, as one of the least studied BMPs, the essential mediators of BMP9-induced osteogenic signaling remain elusive. Here we show that BMP9-induced osteogenic signaling in MSCs requires intact Notch signaling. While the expression of Notch receptors and ligands are readily detectable in MSCs, Notch inhibitor and dominant-negative Notch1 effectively inhibit BMP9-induced osteogenic differentiation in vitro and ectopic bone formation in vivo. Genetic disruption of Notch pathway severely impairs BMP9-induced osteogenic differentiation and ectopic bone formation from MSCs. Furthermore, while BMP9-induced expression of early-responsive genes is not affected by defective Notch signaling, BMP9 upregulates the expression of Notch receptors and ligands at the intermediate stage of osteogenic differentiation. Taken together, these results demonstrate that Notch signaling may play an essential role in coordinating BMP9-induced osteogenic differentiation of MSCs.