Ethnic variation in lower face anthropometry on facial computed tomography scans for patients seeking facial feminization surgery.

BACKGROUND: Facial feminization surgery (FFS) is the most common form of facial gender-affirming surgery. One of the current knowledge gaps is the understanding of differences among racial groups in baseline craniofacial norms for transgender and nonbinary patients. METHODS: All patients who sought consultation for FFS and underwent craniofacial computed tomography (CT) scans at a single institution between 2018 and 2023 were included. Patients who underwent previous facial surgeries were excluded. Chart reviews were conducted for patient characteristics, including race, age, hormone therapy duration, and prior gender-affirming surgeries. Racial categorizations included White, Latinx, African American, or Asian. Patients with other or multiracial identities were excluded. Lower face measurements were derived from preoperative facial CT scans. Comparative analyses were performed on all measurements among the racial groups. RESULTS: In this study, 204 patients were included with an average age of 32.0 ± 10.2 years and a median hormone therapy duration of 2.0 years. The notable differences among the racial groups were: 1. Zygomatic width was the largest in Asian patients (13.5 ± 0.6 cm) compared to all other racial groups (p = 0.03), 2. Nasolabial angle was the smallest in African American patients (82.5 ± 13.1 degrees, p < 0.001), 3. Lower face height was the largest in African American patients (6.9 ± 0.7 cm, p < 0.001), and 4. Lateral mandibular flare was the largest in African American patients (0.4 ± 0.1 cm) and the smallest in Latinx patients (0.2 ± 0.1 cm, p < 0.001). CONCLUSIONS: Specific target areas of FFS should be carefully considered to account for possible baseline ethnic differences. Relative facial proportions may also be a more salient surgical planning tool in transgender and gender nonbinary patients rather than absolute measurements alone.

Long-term outcomes of sphincter pharyngoplasty in patients with cleft palate.

OBJECTIVE: The purpose of this study was to evaluate long-term outcomes of sphincter pharyngoplasties, including speech outcomes, revision surgeries, and postoperative incidence of obstructive sleep apnea (OSA). DESIGN: Retrospective matched-cohort study SETTING: Two craniofacial centers in Los Angeles, CA PATIENTS: Patients (n = 166) with cleft lip and palate (CLP) or isolated cleft palate (iCP) who underwent sphincter pharyngoplasty from 1992 to 2022 were identified. An age- and diagnosis-matched control group of 67 patients with CLP/iCP without velopharyngeal insufficiency (VPI) was also identified. INTERVENTIONS: The pharyngoplasty group underwent sphincter pharyngoplasty, whereas the non-VPI group had no history of VPI surgery or sphincter pharyngoplasty. MAIN OUTCOME MEASURES: Postoperative speech outcomes, revision surgeries, and incidence of OSA were evaluated. Multivariable regression was used to evaluate independent predictors of OSA. RESULTS: Among the patients in the pharyngoplasty cohort, 63.9% demonstrated improved and sustained speech outcomes after a single pharyngoplasty, with a median postoperative follow-up of 8.8 years (interquartile range [IQR], 3.6-12.0 years). One-third of the patients who underwent pharyngoplasty required a revision surgery, with a median time to primary revision of 3.9 years (IQR, 1.9-7.0 years). OSA rates increased significantly among the pharyngoplasty cohort, from 3% before surgery to 14.5% after surgery (p < 0.001). The average time from sphincter pharyngoplasty to OSA diagnosis was 4.4 ± 2.4 years. Multivariable analysis results indicated that sphincter pharyngoplasty surgery was independently associated with a fourfold increase in OSA (p = 0.03). CONCLUSIONS: Although sphincter pharyngoplasty remains successful in improving long-term speech outcomes, persistent OSA is a sequela that should be monitored beyond the immediate postoperative period.

United States Health Policies on Gender-Affirming Care in 2022.

BACKGROUND: Within the United States, access to gender-affirming operations covered by health insurance has increased dramatically over the past decade. However, the perpetually changing landscape and inconsistencies of individual state health policies governing private and public insurance coverage present a lack of clarity for reconstructive surgeons and other physicians attempting to provide gender-affirming care. This work systematically reviewed the current U.S. health policies for both private insurance and Medicaid on a state-by-state basis. METHODS: Individual state health policies in effect as of August of 2022 on gender-affirming care were reviewed using the LexisNexis legal database, state legislature publications, and Medicaid manuals. Primary outcomes were categorization of policies as protective, restrictive, or unclear for each state. Secondary outcomes included analyses of demographics covered by current health policies and geographic differences. RESULTS: Protective state-level health policies related to gender-affirming care were present in approximately half of the nation for both private insurance (49.0%) and Medicaid (52.9%). Explicitly restrictive policies were found in 5.9% and 17.6% of states for private insurance and Medicaid, respectively. Regionally, the Northeast and West had the highest rates of protective policies, whereas the Midwest and South had the highest rates of restrictive policies on gender-affirming care. CONCLUSIONS: State-level health policies on gender-affirming care vary significantly across the United States with regional associations. Clarity in the current and evolving state-specific health policies governing gender-affirming care is essential for surgeons and physicians caring for transgender and gender-diverse individuals.

Bone-Anchored Maxillary Protraction for Adolescents with Cleft Palate and Class III Malocclusion: A Case Series.

To describe the long-term treatment course of bone-anchored maxillary protraction (BAMP) and evaluate orthognathic surgical indications after BAMP.Retrospective case series.Craniofacial/Cleft Palate Program at the Orthopaedic Institute for Children in Los Angeles, CA.Twelve male patients with cleft palate (CP), unilateral cleft lip and palate (UCLP), or bilateral cleft lip and palate (BCLP) and Class III malocclusion treated with BAMP (mean age: 11.4 ± 2.6 years) were included.BAMP treatment was performed by placement of bone-anchored maxillary and mandibular plates connected with intraoral Class III dental elastics or maxillary plates connected to a facemask.We retrospectively assessed BAMP treatment variables, including age at surgery, revision surgeries, and treatment duration. The primary goal was correction to class I occlusion.Twelve patients underwent BAMP treatment for an average of 4.4 ± 2.4 years. Two patients were corrected to class I occlusion at the time of this report. Le Fort I advancement was no longer required in two patients (16.7%), it was required for nine patients (75.0%) and was completed for one patient following BAMP treatment (8.3%).This preliminary report demonstrated that BAMP treatment may be associated with a minimal reduction in the requirement for Le Fort I advancement at skeletal maturity. Future studies with larger sample sizes are necessary to confirm this association.

Duration of Feminizing Hormone Therapy on Facial Fat Volumes.

BACKGROUND: Gender-affirming feminizing hormone therapy induces body fat redistribution. However, the amount and timing of facial fat changes in response to feminizing hormone therapy are unknown, albeit relevant to counseling and surgical planning for facial gender-affirming surgery. In this work, we assessed the influence of feminizing hormone therapy duration on malar and temporal fat volume. METHODS: Malar and temporal fat volumes were compared using computed tomography in transfeminine patients (age 20-29 years, body mass index [BMI] 18.5-24.9) treated with feminizing hormone therapy for <2 years versus ≥2 years. Patients with prior surgical or non-surgical facial soft-tissue interventions were excluded. Multivariable linear regressions evaluated the contribution of hormone therapy duration to malar and temporal fat volumes. RESULTS: 45 patients were included with 30 patients (66.7%) treated with feminizing hormone therapy for ≥2 years and 15 patients (33.3%) treated for <2 years (median[interquartile range, IQR]: 44.5[33.5-65.6] vs. 15.0[11.0-18.0] months, p<0.001). Patients treated with hormone therapy for ≥2 years demonstrated a 1.6-fold greater malar fat volume (5.5[4.2-6.3] vs. 3.4[2.3-4.2] cm 3,p<0.001) and 1.4-fold greater temporal fat volume (2.8[2.4-3.6] cm 3 vs. 2.0[1.7-2.4] cm 3, p=0.01) compared to those treated for <2 years. When accounting for other contributory variables such as BMI, skull size, and total soft-tissue depth in multivariable linear regression models, hormone therapy duration ≥2 years independently predicted higher malar (ß=0.51, p<0.001) and temporal (ß=0.32, p=0.02) fat volumes. CONCLUSIONS: Feminizing hormone therapy increases malar and temporal fat volumes by approximately 2 cm 3 and 0.8 cm 3 for each area, respectively, after 2 years of treatment.

Meta-Analysis and Meta-Regression of Complications and Failures of Autologous Heterotopic Cranial Bone versus Alloplastic Cranioplasties.

BACKGROUND: Fresh autologous cranial bone graft has been traditionally regarded as the ideal cranioplasty material, however long-term comparisons of outcomes with modern alloplastic materials are absent in the literature. In this work, we evaluated complications and failures among cranioplasties performed with fresh, heterotopic, cranial bone graft versus three common alloplastic materials. METHODS: Random-effects meta-analyses of logit-transformed proportions were performed on studies published between 1971-2021 to evaluate complications and failures of cranioplasties performed with fresh, autologous, heterotopic cranial bone, polyetheretherketone (PEEK), polymethylmethacrylate (PMMA), or titanium with a mean follow-up ≥12 months. Generalized mixed model meta-regressions were performed to account for heterogeneity and to evaluate the contributions of moderators to outcomes variables. RESULTS: 1490 patients (mean age 33.9±10.8 years) were included. Pooled, all-cause complications were 6.2% for fresh, heterotopic, autologous cranial bone (95% confidence interval [CI]:2.1-17.0%; I2=55.0%, p=0.02), 18.5% for PEEK (95%CI:14.0-24.0%; I2=0.0%, p=0.58), 26.1% for titanium (95%CI:18.7-35.1%; I2=60.6%, p<0.01), and 28.4% for PMMA (95%CI:12.9-51.5%; I2=88.5%, p<0.01). Pooled all-cause failures were 2.2% for fresh, autologous cranial bone (95%CI:0.4-10.6%; I2=0.0%, p=0.45), 6.3% for PEEK (95%CI:3.2-12.3%; I2=15.5%, p=0.31), 11.4% for titanium (95%CI:6.7-18.8%; I2=60.8%, p<0.01), and 12.7% for PMMA (95%CI:6.9-22.0%; I2=64.8%, p<0.01). Meta-regression models indicated that each alloplastic subtype significantly and independently predicted higher complications, while titanium and PMMA were significant predictors for all-cause failures compared to autologous bone. All three subtypes were predictive of higher cranioplasty failures secondary to infection compared to autologous bone. CONCLUSIONS: Cranioplasties performed with fresh, autologous heterotopic cranial bone grafts resulted in lower complications and failures compared to alloplastic materials.

Indole-Based and Cyclopentenylindole-Based Analogues Containing Fluorine Group as Potential 18F-Labeled Positron Emission Tomography (PET) G-Protein Coupled Receptor 44 (GPR44) Tracers.

Recently, growing evidence of the relationship between G-protein coupled receptor 44 (GPR44) and the inflammation-cancer system has garnered tremendous interest, while the exact role of GPR44 has not been fully elucidated. Currently, there is a strong and urgent need for the development of non-invasive in vivo GPR44 positron emission tomography (PET) radiotracers that can be used to aid the exploration of the relationship between inflammation and tumor biologic behavior. Accordingly, the choosing and radiolabeling of existing GPR44 antagonists containing a fluorine group could serve as a viable method to accelerate PET tracers development for in vivo imaging to this purpose. The present study aims to evaluate published (2000-present) indole-based and cyclopentenyl-indole-based analogues of the GPR44 antagonist to guide the development of fluorine-18 labeled PET tracers that can accurately detect inflammatory processes. The selected analogues contained a crucial fluorine nuclide and were characterized for various properties including binding affinity, selectivity, and pharmacokinetic and metabolic profile. Overall, 26 compounds with favorable to strong binding properties were identified. This review highlights the potential of GPR44 analogues for the development of PET tracers to study inflammation and cancer development and ultimately guide the development of targeted clinical therapies.

An enhanced recovery after surgery protocol for facial feminization surgery reduces perioperative opioid usage, pain, and hospital stay.

BACKGROUND: Prescription drug misuse in transgender individuals is estimated to be three times higher than that of the general population in the United States, suggesting that opioid-reduction strategies deserve significant consideration in gender-affirming surgeries. In this work, we describe the implementation of an enhanced recovery after surgery (ERAS) protocol to reduce opioid use after facial feminization surgery. METHODS: A total of 79 patients who underwent single-stage facial feminization surgery before (n = 38) or after (n = 41) ERAS protocol implementation were included. Primary outcomes assessed were perioperative opioid consumption (morphine equivalent dose/kilogram, MED/kg), average patient-reported pain scores, and length of hospital stay. Comparisons between groups and multivariable linear regression analyses were conducted to define the contribution of the ERAS protocol to each of the three primary outcomes. RESULTS: Age, body mass index, mental health diagnoses, and length of surgery did not differ between pre-ERAS and ERAS groups. Compared to pre-ERAS patients, patients treated under the ERAS protocol consumed less opioids (median [interquartile range, IQR], 0.8 [0.5-1.1] versus 1.5 [1.0-2.1] MED/kg, p < 0.001), reported lower pain scores (2.5 ± 1.8 versus 3.7 ± 1.6, p = 0.002), and required a shorter hospital stay (median [IQR], 27.3 [26.3-49.8] versus 32.4 [24.8-39.1] h, p < 0.001). When controlling for other contributing variables such as previous gender-affirming surgeries, mental health diagnoses, and length of surgery using multivariable linear regression analyses, ERAS protocol implementation independently predicted reduced opioid use, lower pain scores, and shorter hospital stay after facial feminization surgery. CONCLUSIONS: The current work details an ERAS protocol for facial feminization surgery that reduces perioperative opioid consumption, patient-reported pain scores, and hospital stays.

Physician behaviors associated with increased physician and nurse communication during bedside interdisciplinary rounds.

BACKGROUND: Effective team communication during interdisciplinary rounds (IDRs) is a hallmark of safe, efficient, patient-centered care. However, there is limited understanding of optimal IDR structures and procedures. OBJECTIVE: This study aimed to analyze direct observations of physician and nurse interactions during bedside IDR to identify behaviors associated with increased interprofessional communication. DESIGNS, SETTINGS AND PARTICIPANTS: Trained observers audited general medicine ward rounds at an academic medical center using a standardized tool to record physician and nurse behavior and communication in 1007 patient encounters in October 2019 to March 2020. RESULTS: There were significant differences in physician and nurse interaction time among physicians with different levels of training, with attendings demonstrating higher interaction time than residents (5.4 ± 4.6 vs. 4.3 ± 3.7 min, p = .02) and interns or medical students (3.0 ± 3.2 min, p = .002). Attendings were more likely to initiate a conversation about nurse concerns (76.9%) compared to residents (67.9%) and interns or medical students (59.3%, p = .03). Early nurse participation in bedside visits was associated with increased physician and nurse interaction time (5.0 ± 4.6 vs. 1.9 ± 1.7 min, p < .001) and physician initiative to ask about nurse concerns (74.8% vs. 64.3%, p = .04). In addition, physician initiative to ask the nurse for concerns rather than waiting for the nurse to offer concerns without being prompted was associated with a subsequent conversation about those concerns (74.5% vs. 61.8%, p < .001) and the physician asking about patient or family concerns (94.2% vs. 88.4%, p = .01). CONCLUSIONS: Implementing IDR structures and procedures that promote attending physician involvement, physician initiative, and early nurse participation could optimize interdisciplinary communication and quality of care.

Design, Synthesis, Computational and Biological Evaluation of Novel Structure Fragments Based on Lithocholic Acid (LCA).

The regulation of bile acid pathways has become a particularly promising therapeutic strategy for a variety of metabolic disorders, cancers, and diseases. However, the hydrophobicity of bile acids has been an obstacle to clinical efficacy due to off-target effects from rapid drug absorption. In this report, we explored a novel strategy to design new structure fragments based on lithocholic acid (LCA) with improved hydrophilicity by introducing a polar "oxygen atom" into the side chain of LCA, then (i) either retaining the carboxylic acid group or replacing the carboxylic acid group with (ii) a diol group or (iii) a vinyl group. These novel fragments were evaluated using luciferase-based reporter assays and the MTS assay. Compared to LCA, the result revealed that the two lead compounds 1a-1b were well tolerated in vitro, maintaining similar potency and efficacy to LCA. The MTS assay results indicated that cell viability was not affected by dose dependence (under 25 µM). Additionally, computational model analysis demonstrated that compounds 1a-1b formed more extensive hydrogen bond networks with Takeda G protein-coupled receptor 5 (TGR5) than LCA. This strategy displayed a potential approach to explore the development of novel endogenous bile acids fragments. Further evaluation on the biological activities of the two lead compounds is ongoing.

Convergence of Calcium Channel Regulation and Mechanotransduction in Skeletal Regenerative Biomaterial Design.

Cells are known to perceive their microenvironment through extracellular and intracellular mechanical signals. Upon sensing mechanical stimuli, cells can initiate various downstream signaling pathways that are vital to regulating proliferation, growth, and homeostasis. One such physiologic activity modulated by mechanical stimuli is osteogenic differentiation. The process of osteogenic mechanotransduction is regulated by numerous calcium ion channels-including channels coupled to cilia, mechanosensitive and voltage-sensitive channels, and channels associated with the endoplasmic reticulum. Evidence suggests these channels are implicated in osteogenic pathways such as the YAP/TAZ and canonical Wnt pathways. This review aims to describe the involvement of calcium channels in regulating osteogenic differentiation in response to mechanical loading and characterize the fashion in which those channels directly or indirectly mediate this process. The mechanotransduction pathway is a promising target for the development of regenerative materials for clinical applications due to its independence from exogenous growth factor supplementation. As such, also described are examples of osteogenic biomaterial strategies that involve the discussed calcium ion channels, calcium-dependent cellular structures, or calcium ion-regulating cellular features. Understanding the distinct ways calcium channels and signaling regulate these processes may uncover potential targets for advancing biomaterials with regenerative osteogenic capabilities.

Association of Patient-Reported Anxiety and Pain After Alveolar Bone Grafting.

OBJECTIVE: To evaluate the role of psychosocial well-being on perioperative pain and opioid use among patients with cleft lip and palate (CLP) undergoing alveolar bone grafting (ABG). DESIGN: Retrospective review. SETTING: Tertiary level craniofacial clinic. PARTICIPANTS: 34 patients with CLP (median age: 11.7 years), including 25 (73.5%) unilateral CLP and 9 (26.5%) bilateral CLP, who underwent ABG from 2015 to 2022. INTERVENTIONS: ABG using iliac crest bone graft. Patients were prospectively administered four patient-reported psychosocial instruments from the Patient-Reported Outcomes Measurement Information System. MAIN OUTCOME MEASURES: Perioperative opioid use in morphine equivalent dosage/kilogram, patient-reported pain scores, and length of hospital stay after ABG. RESULTS: Patient-reported anxiety (r = 0.41, p = 0.02) and depressive symptoms (r = 0.35, p = 0.04) correlated to higher perioperative opioid usage. Multivariable regression models including psychosocial scores, total acetaminophen usage, length of surgery, and other simultaneous surgeries were developed for total opioid usage, patient-reported pain, and length of hospital stay. Patient-reported anxiety was independently predictive of higher perioperative opioid use (ß=0.36, p = 0.01) and higher pain scores (ß=0.39, p = 0.02), but not length of hospital stay. CONCLUSIONS: We identified an association for patient-reported anxiety and perioperative opioid use and pain in a CLP cohort undergoing ABG. Future considerations in preoperative patient and family consultation may be indicated in patients self-reporting higher anxiety in an effort to minimize perioperative opioid usage.

Modulating Temporospatial Phosphate Equilibrium by Nanoparticulate Mineralized Collagen Materials Induces Osteogenesis via PiT-1 and PiT-2.

The temporospatial equilibrium of phosphate contributes to physiological bone development and fracture healing, yet optimal control of phosphate content has not been explored in skeletal regenerative materials. Nanoparticulate mineralized collagen glycosaminoglycan (MC-GAG) is a synthetic, tunable material that promotes in vivo skull regeneration. In this work, the effects of MC-GAG phosphate content on the surrounding microenvironment and osteoprogenitor differentiation are investigated. This study finds that MC-GAG exhibits a temporal relationship with soluble phosphate with elution early in culture shifting to absorption with or without differentiating primary bone marrow-derived human mesenchymal stem cells (hMSCs). The intrinsic phosphate content of MC-GAG is sufficient to stimulate osteogenic differentiation of hMSCs in basal growth media without the addition of exogenous phosphate in a manner that can be severely reduced, but not eliminated, by knockdown of the sodium phosphate transporters PiT-1 or PiT-2. The contributions of PiT-1 and PiT-2 to MC-GAG-mediated osteogenesis are nonredundant but also nonadditive, suggestive that the heterodimeric form is essential to its activity. These findings indicate that the mineral content of MC-GAG alters phosphate concentrations within a local microenvironment resulting in osteogenic differentiation of progenitor cells via both PiT-1 and PiT-2.

Osteoprotegerin-eluting nanoparticulate mineralized collagen scaffolds improve skull regeneration.

Custom synthesis of extracellular matrix (ECM)-inspired materials for condition-specific reconstruction has emerged as a potentially translatable regenerative strategy. In skull defect reconstruction, nanoparticulate mineralized collagen glycosaminoglycan scaffolds (MC-GAG) have demonstrated osteogenic and anti-osteoclastogenic properties, culminating in the ability to partially heal in vivo skull defects without the addition of exogenous growth factors or progenitor cell loading. In an effort to reduce catabolism during early skull regeneration, we fabricated a composite material (MCGO) of MC-GAG and recombinant osteoprotegerin (OPG), an endogenous anti-osteoclastogenic decoy receptor. In the presence of differentiating osteoprogenitors, MCGO demonstrated an additive effect with endogenous OPG limited to the first 14 days of culture with total eluted and scaffold-bound OPG exceeding that of MC-GAG. Functionally, MCGO exhibited similar osteogenic properties as MC-GAG, however, MCGO significantly reduced maturation and resorptive activities of primary human osteoclasts. In a rabbit skull defect model, MCGO scaffold-reconstructed defects displayed higher mineralization as well as increased hardness and microfracture resistance compared to non-OPG functionalized MC-GAG scaffolds. The current work suggests that MCGO is a development in the goal of reaching a materials-based strategy for skull regeneration.

COVID-19 Pandemic Associated With Increased Self-reported Depressive Symptoms in Patients With Congenital Craniofacial Diagnoses.

OBJECTIVE: The current study investigated the influence of the coronavirus (COVID-19) pandemic on patients with congenital craniofacial diagnoses. METHODS: Patients (n = 66) with craniofacial diagnoses aged between 8 and 17 were prospectively evaluated with longitudinal psychosocial assessments using the anger, anxiety, depressive symptoms, and peer relationships instruments within the pediatric Patient-Reported Outcomes Measurement Information System (PROMIS). The COVID-19 cohort (n = 33) included patients with assessments within 2 years prior to the pandemic (t0) and during the pandemic (t1; March 2020 to March 2021). An age-matched comparison cohort (n = 33) with similar demographics and diagnoses included patients assessed twice over 3 years prior to the pandemic. RESULTS: All PROMIS measures were in the average range clinically for both groups across time points. However, the COVID-19 group reported a significant increase in depressive symptoms during the pandemic (t1) compared to pre-pandemic (t0) scores (48.2 ± 10.1 vs 44.3 ± 9.4, P = .04, d = -0.37), while the comparison group did not demonstrate any differences in psychosocial functioning between t0 and t1. For the COVID-19 cohort, only the pandemic timeframe (r = 0.21, P = .03) was significantly associated with increased depressive symptom scores, and no other sociodemographic or medical variables were associated with depressive symptoms. CONCLUSIONS: Self-reported depressive symptoms increased during the COVID-19 pandemic in patients with congenital craniofacial diagnoses. Longitudinal studies are needed to elucidate whether such changes will be persistent or compound known variables associated with psychosocial functioning.

Biodistribution of Intra-Arterial and Intravenous Delivery of Human Umbilical Cord Mesenchymal Stem Cell-Derived Extracellular Vesicles in a Rat Model to Guide Delivery Strategies for Diabetes Therapies.

Umbilical cord mesenchymal stem cell-derived extracellular vesicles (UC-MSC-EVs) have become an emerging strategy for treating various autoimmune and metabolic disorders, particularly diabetes. Delivery of UC-MSC-EVs is essential to ensure optimal efficacy of UC-MSC-EVs. To develop safe and superior EVs-based delivery strategies, we explored nuclear techniques including positron emission tomography (PET) to evaluate the delivery of UC-MSC-EVs in vivo. In this study, human UC-MSC-EVs were first successfully tagged with I-124 to permit PET determination. Intravenous (I.V.) and intra-arterial (I.A.) administration routes of [124I]I-UC-MSC-EVs were compared and evaluated by in vivo PET-CT imaging and ex vivo biodistribution in a non-diabetic Lewis (LEW) rat model. For I.A. administration, [124I]I-UC-MSC-EVs were directly infused into the pancreatic parenchyma via the celiac artery. PET imaging revealed that the predominant uptake occurred in the liver for both injection routes, and further imaging characterized clearance patterns of [124I]I-UC-MSC-EVs. For biodistribution, the uptake (%ID/gram) in the spleen was significantly higher for I.V. administration compared to I.A. administration (1.95 ± 0.03 and 0.43 ± 0.07, respectively). Importantly, the pancreas displayed similar uptake levels between the two modalities (0.20 ± 0.06 for I.V. and 0.24 ± 0.03 for I.A.). Therefore, our initial data revealed that both routes had similar delivery efficiency for [124I]I-UC-MSC-EVs except in the spleen and liver, considering that higher spleen uptake could enhance immunomodulatory application of UC-MSC-EVs. These findings could guide the development of safe and efficacious delivery strategies for UC-MSC-EVs in diabetes therapies, in which a minimally invasive I.V. approach would serve as a better delivery strategy. Further confirmation studies are ongoing.

Ramatroban-Based Analogues Containing Fluorine Group as Potential 18F-Labeled Positron Emission Tomography (PET) G-Protein Coupled Receptor 44 (GPR44) Tracers.

Diabetes remains one of the fastest growing chronic diseases and is a leading source of morbidity and accelerated mortality in the world. Loss of beta cell mass (BCM) and decreased sensitivity to insulin underlie diabetes pathogenesis. Yet, the ability to safely and directly assess BCM in individuals with diabetes does not exist. Measures such as blood glucose provide only a crude indirect picture of beta cell health. PET imaging could, in theory, allow for safe, direct, and precise characterization of BCM. However, identification of beta cell-specific radiolabeled tracers remains elusive. G-protein coupled receptor 44 (GPR44) is a transmembrane protein that was characterized in 2012 as highly beta cell-specific within the insulin-positive islets of Langerhans. Accordingly, radiolabeling of existing GPR44 antagonists could be a viable method to accelerate PET tracer development. The present study aims to evaluate and summarize published analogues of the GPR44 antagonist ramatroban to develop 18F-labeled PET tracers for BCM analysis. The 77 corresponding ramatroban analogues containing a fluorine nuclide were characterized for properties including binding affinity, selectivity, and pharmacokinetic and metabolic profile, and 32 compounds with favorable properties were identified. This review illustrates the potential of GPR44 analogues for the development of PET tracers.