Glioblastoma Spheroid Invasion through Soft, Brain-Like Matrices Depends on Hyaluronic Acid-CD44 Interactions.

Increased secretion of hyaluronic acid (HA), a glycosaminoglycan abundant in the brain extracellular matrix (ECM), correlates with worse clinical outcomes for glioblastoma (GBM) patients. GBM cells aggressively invade the brain parenchyma while encountering spatiotemporal changes in their local ECM, including HA concentration. To investigate how varying HA concentrations affect GBM invasion, patient-derived GBM cells are cultured within a soft, 3D matrix in which HA concentration is precisely varied and cell migration observed. Data demonstrate that HA concentration can determine the invasive activity of patient-derived GBM cells in a biphasic and highly sensitive manner, where the absolute concentration of HA at which cell migration peaked is specific to each patient-derived line. Furthermore, evidence that this response relies on phosphorylated ezrin, which interacts with the intracellular domain of HA-engaged CD44 to effectively link the actin cytoskeleton to the local ECM is provided. Overall, this study highlights CD44-HA binding as a major mediator of GBM cell migration that acts independently of integrins and focal adhesion complexes and suggests that targeting HA-CD44-ezrin interactions represents a promising therapeutic strategy to prevent tumor cell invasion in the brain.

Hydrogel Arrays Enable Increased Throughput for Screening Effects of Matrix Components and Therapeutics in 3D Tumor Models.

Cell-matrix interactions mediate complex physiological processes through biochemical, mechanical, and geometrical cues, influencing pathological changes and therapeutic responses. Accounting for matrix effects earlier in the drug development pipeline is expected to increase the likelihood of clinical success of novel therapeutics. Biomaterial-based strategies recapitulating specific tissue microenvironments in 3D cell culture exist but integrating these with the 2D culture methods primarily used for drug screening has been challenging. Thus, the protocol presented here details the development of methods for 3D culture within miniaturized biomaterial matrices in a multi-well plate format to facilitate integration with existing drug screening pipelines and conventional assays for cell viability. Since the matrix features critical for preserving clinically relevant phenotypes in cultured cells are expected to be highly tissue- and disease-specific, combinatorial screening of matrix parameters will be necessary to identify appropriate conditions for specific applications. The methods described here use a miniaturized culture format to assess cancer cell responses to orthogonal variation of matrix mechanics and ligand presentation. Specifically, this study demonstrates the use of this platform to investigate the effects of matrix parameters on the responses of patient-derived glioblastoma (GBM) cells to chemotherapy.

Adherence to nasal positive airway pressure therapy among school-aged children and adolescents with obstructive sleep apnea syndrome.

OBJECTIVES: Although many children with obstructive sleep apnea syndrome have complete resolution of obstructive sleep apnea syndrome after adenotonsillectomy, some patients have persistent obstructive sleep apnea syndrome requiring positive airway pressure treatment. Little is known about positive airway pressure adherence among school-aged children and adolescents. PATIENTS AND METHODS: We retrospectively reviewed records from January 2000 through December 2004 to assess positive airway pressure adherence following a comprehensive patient- and parent-focused positive airway pressure education program for children 7 to 19 years of age with persistent obstructive sleep apnea syndrome subsequent to indicated adenotonsillectomy. A polysomnogram was obtained before and after initiation of positive airway pressure therapy. Adherence was defined as > 4 hours per night and > or = 5 nights per week of positive airway pressure use. Clock-counter meters determined hours per night and nights per week of positive airway pressure use; parents estimated hours per night of positive airway pressure use. Nonparametric tests assessed associations between adherence and various clinical parameters and symptoms. RESULTS: Forty-six patients (56% male; 39% black, 61% white; mean age: 13.6 years; mean BMI: 39.8 kg/m2) were included. Two refused positive airway pressure. Meter readings were available for 27 patients (59%); positive airway pressure was used, on average, 7.0 hours per night, 73% of the week, and for a mean of 18.1 months. Nineteen (70%) were adherent regardless of age. There was good agreement between parental report and meter readings. Patients with greater improvement in apnea-hypopnea index were more likely to be adherent. Clinical parameters and symptoms improved after positive airway pressure therapy regardless of age or adherence. CONCLUSIONS: In this retrospective study, positive airway pressure adherence and symptom improvement among school-aged children and adolescents was achieved with comprehensive patient and parent education and follow-up.