I-Ping Chen's research while affiliated with University of Connecticut and other places

Craniometaphyseal dysplasia (CMD), a rare craniotubular disorder, occurs in an autosomal dominant (AD) or autosomal recessive (AR) form. CMD is characterized by hyperostosis of craniofacial bones and flaring metaphyses of long bones. Many patients with CMD suffer from neurological symptoms. To date, the pathogenesis of CMD is not fully understood. Treatment is limited to decompression surgery. Here, we report a knock in (KI) mouse model for AR CMD carrying a R239Q mutation in CX43. Cx43KI/KI mice replicate many features of AR CMD in craniofacial and long bones. In contrast to Cx43+/+ littermates, Cx43KI/KI mice exhibit periosteal bone deposition and increased osteoclast (OC) numbers in the endosteum of long bones, leading to an expanded bone marrow cavity and increased cortical bone thickness. Although formation of Cx43+/+ and Cx43KI/KI resting OCs are comparable, on bone chips the actively resorbing Cx43KI/KI OCs resorb less bone. Cortical bones of Cx43KI/KI mice have an increase in degenerating osteocytes and empty lacunae. Osteocyte dendrite formation is decreased with reduced expression levels of Fgf23, Sost, Tnf-α, IL-1β, Esr1, Esr2, and a lower Rankl/Opg ratio. Female Cx43KI/KI mice display a more severe phenotype. Sexual dimorphism in bone becomes more evident as mice age. Our data show that the CX43R239Q mutation results in mislocalization of CX43 protein and impairment of gap junction and hemichannel activity. Different from CX43 ablation mouse models, the CX43R239Q mutation leads to the AR CMD-like phenotype in Cx43KI/KI mice not only by loss-of-function but also via a not yet revealed dominant function.

Currently, over 500 rare genetic bone disorders are identified. These diseases are often accompanied by dental abnormalities, which are sometimes the first clue for an early diagnosis. However, not many dentists are sufficiently familiar with phenotypic abnormalities and treatment approaches when they encounter patients with rare diseases. Such patients often need dental treatment but have difficulties in finding a dentist who can treat them appropriately. Herein we focus on major dental phenotypes and summarize their potential causes and mechanisms, if known. We discuss representative diseases, dental treatments, and their effect on the oral health of patients and on oral health‐related quality of life. This review can serve as a starting point for dentists to contribute to early diagnosis and further investigate the best treatment options for patients with rare disorders, with the goal of optimizing treatment outcomes.

Cherubism is a rare autosomal dominant disease caused mainly by a P416R point mutation of Src homology 3 Domain Binding Protein 2 (SH3BP2). Though macrophages and osteoblasts were thought to be the major contributors to the pathology in the past, the involvement of neutrophils in cherubism has been demonstrated by the increasing neutrophil infiltration and extensive neutrophil extracellular trap formation in the lesion recently. Here, we observed decreased expression of lineage marker Ly6G and impaired integrin activation on neutrophils, indicating a developmental defect of neutrophils in cherubism mice carrying the SH3BP2 P416R mutation. Furthermore, we performed single-cell RNA sequencing and compared transcriptomes between blood neutrophils, bone marrow neutrophils, and bone marrow leukocyte progenitors from wildtype and SH3BP2 P416R mice. RNA velocity and pathway analysis show that mutated neutrophils have stalled in the early stage of neutrophil development and failed to mature into granzyme pathway-enhanced, NET-formation-restrained mature neutrophil population in wildtype. Together, our study first illustrates the neutrophil development defects in cherubism as a mechanism for hyperinflammation characterized in cherubism. Ziming Cao and Keaton Karlinsey contributed equally. Beiyan Zhou, I-Ping Chen and Zhichao Fan are co-corresponding authors. This research was supported by grants from the National Institutes of Health, National Heart, Lung, and Blood Institute, USA (R01HL145454), and a startup fund from UConn Health. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Purpose Craniometaphyseal dysplasia (CMD) is a rare skeletal disorder that has progressive thickening and increased density of the craniofacial bones along with abnormal metaphyses of the long bones. Other features include a wide nasal bridge, paranasal bossing, hypertelorism, and an increase in the zygomatic width. We present a series of cases that showcase the three-dimensional radiographic features of this rare condition and compare it with an age and gender-matched controlled group using cone beam computed tomography (CBCT). Objective To evaluate the three-dimensional radiographic features of craniometaphyseal dysplasia (CMD). Materials and methods Retrospective analysis of CBCT scans of 7 patients who were diagnosed with the rare condition craniometaphyseal dysplasia was evaluated. Radiographic features of the craniofacial bones, the paranasal sinuses prominently maxillary, and frontal and sphenoid sinuses were evaluated. Skull bones were also evaluated, and the size and shape of the sella turcica and external auditory meatus were measured. Retained primary teeth and impactions were evaluated using a panoramic reformatted image. The type of occlusion and buccolingual dimensions of jaw bones were also assessed. Age and gender-matched control samples were used to measure the same features for comparing CMD patients to healthy controls. The quality of normal and syndromic patients’ cortical and trabecular bone was determined by measuring pixel intensity values (PIV) generated by CBCT scans. Results Cone beam CT images of patients with CMD were analyzed to evaluate cranial bones, their density, and any abnormalities associated with the sinuses and foramina. Patients with CMD had bones increased in size. A significant increase in the amount of bone formed was found in the inner table of the frontal and occipital bones. All seven patients with CMD had smaller foramina due to the deposition of sclerosed bone in the foramina of the skull base. The paranasal sinuses, prominently maxillary and frontal and sphenoid sinuses, were smaller than the age and gender-matched controls. The buccolingual dimensions of jawbones were increased. The maxillary and mandibular arch relationship ranged from class II to class III. The mean nasal bridge measurement for the CMD patients was 26.77 mm, while in the controls, the mean nasal bridge measurement was 19.48 mm. The mean measurements of the right and left orbits of CMD patients were 30.6 mm and 31.07 mm respectively, and the mean measurements of the right and left orbits of controls were 32.45 mm and 32.04 mm. Pixel intensity values (PIVs) representing density ranged between 100 and 1000 PIVs for cortical bone and between − 60 and 258 for trabecular bone suggesting a densely sclerotic texture, while in the control group patients, the PIVs for cortical bone were > 1000 and 150–300 for trabecular bone. Conclusion CMD patients had significantly larger bone widths, a lower density of the bone, and smaller sinuses compared to the control group.

Dental pain invokes the sympathetic nervous system, which can be measured by electrodermal activity (EDA). In the dental clinic, accurate quantification of pain is needed because it could enable optimized drug-dose treatments, thereby potentially reducing drug addiction. However, a confounding factor is that during pain there is also lingering residual stress, hence, both contribute to the EDA response. Therefore, we investigated whether EDA can differentiate stress from pain during dental examination. The use of electrical pulp test (EPT) is an ideal approach to tease out the dynamics of stress and mimic pain with lingering residual stress. Once the electrical sensation is felt and reaches a critical current threshold, the subject removes the probe from their tooth, hence, this stage of data represents largely EPT stimulus and the residual stress-induced EDA response is smaller. EPT was performed on necrotic and vital teeth in fifty-one subjects. We defined four different data groups of reactions based on each individual's EPT intensity level expectation based on the visual analog scale (VAS) of their baseline trial, as follows: mild stress, mild stress + EPT, strong stress, and strong stress + EPT. EDA-derived features exhibited significant difference between residual lingering stress + EPT groups and stress groups. We obtained 84.6% accuracy with 76.2% sensitivity and 86.8% specificity with multilayer perceptron in differentiating between pure-stress groups vs. stress + EPT groups. Moreover, EPT induced much greater EDA amplitude and faster response than stress. Our finding suggests that our machine learning approach can discriminate between stress and EPT stimulation in EDA signals.

Bio-signals are being increasingly used for the assessment of pathophysiological conditions including pain, stress, fatigue, and anxiety. For some approaches, a single signal is not sufficient to provide a comprehensive diagnosis; however, there is a growing consensus that multimodal approaches allow higher sensitivity and specificity. For instance, in visceral pain subjects, the autonomic activation can be inferred using electrodermal activity (EDA) and heart rate variability derived from the electrocardiogram (ECG), but including the muscle activation detected from the surface electromyogram (sEMG) can better differentiate the disease that causes the pain. There is no wearable device commercially capable of collecting these three signals simultaneously. This paper presents the validation of a novel multimodal low profile wearable data acquisition device for the simultaneous collection of EDA, ECG, and sEMG signals. The device was validated by comparing its performance to laboratory-scale reference devices. N = 20 healthy subjects were recruited to participate in a four-stage study that exposed them to an array of cognitive, orthostatic, and muscular stimuli, ensuring the device is sensitive to a range of stressors. Time and frequency domain analyses for all three signals showed significant similarities between our device and the reference devices. Correlation of sEMG metrics ranged from 0.81 to 0.95 and EDA/ECG metrics showed few instances of significant difference in trends between our device and the references. With only minor observed differences, we demonstrated the ability of our device to collect EDA, sEMG, and ECG signals. This device will enable future practical and impactful advances in the field of chronic pain and stress measurement and can confidently be implemented in related studies.

Aims: To explore whether electrodermal activity (EDA) can serve as a complementary tool for pulpal diagnosis (Aim 1) and an objective metric to assess dental pain before and after local anaesthesia (Aim 2). Methodology: A total of 53 subjects (189 teeth) and 14 subjects (14 teeth) were recruited for Aim 1 and Aim 2, respectively. We recorded EDA using commercially available devices, PowerLab and Galvanic Skin Response (GSR) Amplifier, in conjunction with cold and electric pulp testing (EPT). Participants rated their level of sensation on a 0-10 visual analogue scale (VAS) after each test. We recorded EPT-stimulated EDA activity before and after the administration of local anaesthesia for participants who required root canal treatment (RCT) due to painful pulpitis. The raw data were converted to the time-varying index of sympathetic activity (TVSymp), a sensitive and specific parameter of EDA. Statistical analysis was performed using Python 3.6 and its Scikit-post hoc library. Results: Electrodermal activity was upregulated by the stimuli of cold and EPT testing in the normal pulp. TVSymp signals were significantly increased in vital pulp compared to necrotic pulp by both cold test and EPT. Teeth that exhibited intensive sensitivity to cold with or without lingering pain had increased peak numbers of TVSymp than teeth with mild sensation to cold. Pre- and post-anaesthesia EDA activity and VAS scores were recorded in patients with painful pulpitis. Post-anaesthesia EDA signals were significantly lower compared to pre-anaesthesia levels. Approximately 71% of patients (10 of 14 patients) experienced no pain during treatment and reported VAS score of 0 or 1. The majority of patients (10 of 14) showed a reduction of TVSymp after the administration of anaesthesia. Two of three patients who experienced increased pain during RCT (post-treatment VAS > pre-treatment VAS) exhibited increased post-anaesthesia TVSymp. Conclusions: Our data show promising results for using EDA in pulpal diagnosis and for assessing dental pain. Whilst our testing was limited to subjects who had adequate communication skills, our future goal is to be able to use this technology to aid in the endodontic diagnosis of patients who have limited communication ability.

Background: Familial hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease and is typically caused by mutations in genes encoding sarcomeric proteins that regulate cardiac contractility. HCM manifestations include left ventricular hypertrophy and heart failure, arrythmias, and sudden cardiac death. How dysregulated sarcomeric force production is sensed and leads to pathological remodeling remains poorly understood in HCM, thereby inhibiting the efficient development of new therapeutics. Methods: Our discovery was based on insights from a severe phenotype of an individual with HCM and a second genetic alteration in a sarcomeric mechanosensing protein. We derived cardiomyocytes from patient-specific induced pluripotent stem cells (iPSC-CMs) and developed robust engineered heart tissues (EHTs) by seeding iPSC-CMs into a laser-cut scaffold possessing native cardiac fiber alignment in order to study human cardiac mechanobiology at both cellular and tissue levels. Coupled with computational modeling for muscle contraction and rescue of disease phenotype via gene editing and pharmacological interventions, we have identified a new mechanotransduction pathway in HCM, shown to be essential in modulating the phenotypic expression of HCM in five families bearing distinct sarcomeric mutations. Results: Enhanced actomyosin crossbridge formation caused by sarcomeric mutations in cardiac myosin heavy chain ( MYH7 ) led to increased force generation, which when coupled with slower twitch relaxation, destabilized the muscle LIM protein (MLP) stretch-sensing complex at the Z-disc. Subsequent reduction in the sarcomeric MLP level caused disinhibition of calcineurin-nuclear factor of activated T-cells (NFAT) signaling, which promoted cardiac hypertrophy. We demonstrate that the common MLP-W4R variant is an important modifier, exacerbating the phenotypic expression of HCM, but alone may not be a disease-causing mutation. By mitigating enhanced actomyosin crossbridge formation through either genetic or pharmacological means, we alleviated stress at the Z-disc, preventing the development of hypertrophy associated with sarcomeric mutations. Conclusions: Our studies have uncovered a novel biomechanical mechanism through which dysregulated sarcomeric force production is sensed and leads to pathological signaling, remodeling, and hypertrophic responses. Together, these establish the foundation for developing innovative mechanism-based treatments for HCM that stabilize the Z-disc MLP mechanosensory complex.

This chapter briefly describes the differentiation of keratinocytes from their precursors to mature cells in the epidermis of the skin and the protective role of the epidermis. In certain genetic skin disorders, the differentiation and function of keratinocytes are impaired. Since primary keratinocytes from patients with those disorders are not always available, there has been much interest to differentiate functional keratinocytes from human induced pluripotent stem cells (hiPSCs) for research and clinical use. Prior to the arrival of iPSC technologies research on keratinocyte differentiation was conducted with embryonic stem cells (ESCs). Similar to ESCs, hiPSCs can give rise to virtually any cell type and can be genetically corrected, allowing the development of therapies for many incurable disorders, including skin diseases. This chapter introduces significant findings that led to the development of keratinocyte differentiation protocols from hiPSCs that either use embryoid bodies, hiPSC colonies, or singularized hiPSCs. We also discuss the potential of skin-derived precursor cells and direct reprogramming of keratinocytes from fibroblasts or adipocytes. The use of hiPSC-derived keratinocytes for patient treatment is still very limited due to safety concerns inherent to the stem cell nature of hiPSCs. However, keratinocyte derivation from hiPSCs is an important research tool for clinical and basic research, not only when patient cells are unavailable. Disease mutations can be repaired by gene editing or can be introduced into healthy cells for research purposes thus creating isogenic cell lines with identical genetic background that differ only by the disease mutation. hiPSCs can be differentiated into typical cell types found in skin and are therefore ideal to generate organotypic skin equivalents for disease research, pharmacologic or cosmetic safety studies, and for toxicological studies. Recently, three-dimensional organotypic skin constructs can be grown in microfluidic devices (skin-on-chip) equipped with biosensors for physiologic and mechanical studies.

Cherubism (CBM), characterized by expansile jawbones with multilocular fibro‐cystic lesions, is caused by gain‐of‐function mutations in SH3 domain‐binding protein 2 (SH3BP2; mouse orthologue Sh3bp2). Loss of jawbone and dental integrity significantly decrease the quality of life for affected children. Treatment for CBM is limited to multiple surgeries to correct facial deformities. Despite significant advances made with CBM knockin (KI) mouse models (Sh3bp2KI/KI), the activation mechanisms of CBM lesions remain unknown because mutant mice do not spontaneously develop expansile jawbones. We hypothesize that bony inflammation of an unknown cause triggers jawbone expansion in CBM. To introduce jawbone inflammation in a spatiotemporally controlled manner, we exposed pulp of the first right mandibular molar of 6‐week‐old Sh3bp2+/+, Sh3bp2KI/+, and Sh3bp2KI/KI mice. Bacterial invasion from the exposed pulp into root canals led to apical periodontitis in wild‐type and mutant mice. This pathogen‐associated molecular patterns (PAMPs)‐induced inflammation of alveolar bone resulted in jawbone expansion in Sh3bp2KI/+ and Sh3bp2KI/KI mice. CBM‐like lesions developed exacerbated inflammation with increased neutrophil, macrophage, and osteoclast numbers. These lesions displayed excessive neutrophil extracellular traps (NETs) compared to Sh3bp2+/+ mice. Expression levels of IL‐1β, IL‐6, and TNF‐α were increased in periapical lesions of Sh3bp2+/+, Sh3bp2KI/+, and Sh3bp2KI/KI mice and also in plasma and the left untreated mandibles (with no pulp exposure) of Sh3bp2KI/KI mice, suggesting a systemic upregulation. Ablation of Tlr2/4 signaling or depletion of neutrophils by Ly6G antibodies ameliorated jawbone expansion induced by PAMPs in Sh3bp2KI/KI mice. In summary, successful induction of CBM‐like lesions in jaws of CBM mice is important for studying initiating mechanisms of CBM and for testing potential therapies. Our findings further emphasize a critical role of host immunity in the development of apical periodontitis and the importance of maintaining oral health in CBM patients. This article is protected by copyright. All rights reserved.