Nanotopography reveals metabolites that maintain the immunomodulatory phenotype of mesenchymal stromal cells.

Mesenchymal stromal cells (MSCs) are multipotent progenitor cells that are of considerable clinical potential in transplantation and anti-inflammatory therapies due to their capacity for tissue repair and immunomodulation. However, MSCs rapidly differentiate once in culture, making their large-scale expansion for use in immunomodulatory therapies challenging. Although the differentiation mechanisms of MSCs have been extensively investigated using materials, little is known about how materials can influence paracrine activities of MSCs. Here, we show that nanotopography can control the immunomodulatory capacity of MSCs through decreased intracellular tension and increasing oxidative glycolysis. We use nanotopography to identify bioactive metabolites that modulate intracellular tension, growth and immunomodulatory phenotype of MSCs in standard culture and during larger scale cell manufacture. Our findings demonstrate an effective route to support large-scale expansion of functional MSCs for therapeutic purposes.

Cell shape and tension alter focal adhesion structure.

Cells are not only anchored to the extracellular matrix via the focal adhesion complex, the focal adhesion complex also serves as a sensor for force transduction. How tension influences the structure of focal adhesions is not well understood. Here, we analyse the effect of tension on the location of key focal adhesion proteins, namely vinculin, paxillin and actin. We use micropatterning on gold surfaces to manipulate the cell shape, to create focal adhesions at specific cell areas, and to perform metal-induced energy transfer (MIET) measurements on the patterned cells. MIET resolves the different protein locations with respect to the gold surface with nanometer accuracy. Further, we use drugs influencing the cellular motor protein myosin or mechanosensitive ion channels to get deeper insight into focal adhesions at different tension states. We show here that in particular actin is affected by the rationally tuned force balance. Blocking mechanosensitive ion channels has a particularly high influence on the actin and focal adhesion architecture, resulting in larger focal adhesions with elevated paxillin and vinculin and strongly lowered actin stress fibres. Our results can be explained by a balance of adhesion tension with cellular tension together with ion channel-controlled focal adhesion homeostasis, where high cellular tension leads to an elevation of vinculin and actin, while high adhesion tension lowers these proteins.

Vitronectin-based hydrogels recapitulate neuroblastoma growth conditions.

The tumor microenvironment plays an important role in cancer development and the use of 3D in vitro systems that decouple different elements of this microenvironment is critical for the study of cancer progression. In neuroblastoma (NB), vitronectin (VN), an extracellular matrix protein, has been linked to poor prognosis and appears as a promising therapeutic target. Here, we developed hydrogels that incorporate VN into 3D polyethylene glycol (PEG) hydrogel networks to recapitulate the native NB microenvironment. The stiffness of the VN/PEG hydrogels was modulated to be comparable to the in vivo values reported for NB tissue samples. We used SK-N-BE (2) NB cells to demonstrate that PEGylated VN promotes cell adhesion as the native protein does. Furthermore, the PEGylation of VN allows its crosslinking into the hydrogel network, providing VN retention within the hydrogels that support viable cells in 3D. Confocal imaging and ELISA assays indicate that cells secrete VN also in the hydrogels and continue to reorganize their 3D environment. Overall, the 3D VN-based PEG hydrogels recapitulate the complexity of the native tumor extracellular matrix, showing that VN-cell interaction plays a key role in NB aggressiveness, and that VN could potentially be targeted in preclinical drug studies performed on the presented hydrogels.

Experimental and Data Analysis Workflow for Soft Matter Nanoindentation.

Nanoindentation refers to a class of experimental techniques where a micrometric force probe is used to quantify the local mechanical properties of soft biomaterials and cells. This approach has gained a central role in the fields of mechanobiology, biomaterials design and tissue engineering, to obtain a proper mechanical characterization of soft materials with a resolution comparable to the size of single cells (µm). The most popular strategy to acquire such experimental data is to employ an atomic force microscope (AFM); while this instrument offers an unprecedented resolution in force (down to pN) and space (sub-nm), its usability is often limited by its complexity that prevents routine measurements of integral indicators of mechanical properties, such as Young's Modulus (E). A new generation of nanoindenters, such as those based on optical fiber sensing technology, has recently gained popularity for its ease of integration while allowing to apply sub-nN forces with µm spatial resolution, therefore being suitable to probe local mechanical properties of hydrogels and cells. In this protocol, a step-by-step guide detailing the experimental procedure to acquire nanoindentation data on hydrogels and cells using a commercially available ferrule-top optical fiber sensing nanoindenter is presented. Whereas some steps are specific to the instrument used herein, the proposed protocol can be taken as a guide for other nanoindentation devices, granted some steps are adapted according to the manufacturer's guidelines. Further, a new open-source Python software equipped with a user-friendly graphical user interface for the analysis of nanoindentation data is presented, which allows for screening of incorrectly acquired curves, data filtering, computation of the contact point through different numerical procedures, the conventional computation of E, as well as a more advanced analysis particularly suited for single-cell nanoindentation data.

Biophysical phenotyping of mesenchymal stem cells along the osteogenic differentiation pathway.

Mesenchymal stem cells represent an important resource, for bone regenerative medicine and therapeutic applications. This review focuses on new advancements and biophysical tools which exploit different physical and chemical markers of mesenchymal stem cell populations, to finely characterize phenotype changes along their osteogenic differentiation process. Special attention is paid to recently developed label-free methods, which allow monitoring cell populations with minimal invasiveness. Among them, quantitative phase imaging, suitable for single-cell morphometric analysis, and nanoindentation, functional to cellular biomechanics investigation. Moreover, the pool of ion channels expressed in cells during differentiation is discussed, with particular interest for calcium homoeostasis.Altogether, a biophysical perspective of osteogenesis is proposed, offering a valuable tool for the assessment of the cell stage, but also suggesting potential physiological links between apparently independent phenomena.

Association between Preoperative Adenomyosis Detection Rate during Pelvic Ultrasonography and the Specialty of the Reading Physician.

STUDY OBJECTIVE: To compare the detection rate of adenomyosis when ultrasound is performed by a radiologist compared with a gynecologic expert sonologist. DESIGN: A retrospective, single-center study. SETTING: A university teaching hospital. PATIENTS: All women above 18 years of age with a positive histopathology diagnosis of adenomyosis obtained in a hysterectomy specimen from October 1, 2011, to October 1, 2017, were screened for inclusion. Cases without a preoperative pelvic ultrasound report, those with coexisting premalignant/malignant conditions, and patients presenting to the clinic with symptoms other than abnormal uterine bleeding, dysmenorrhea, or abdominal pain were excluded. A total of 412 cases were included in the final analysis. MEASUREMENTS AND MAIN RESULTS: The preoperative ultrasound was performed by a radiologist in 241 patients (59%) and by an expert gynecologic sonologist in 171 patients (42%). Patients' age, body mass index, race, ethnicity, parity, and history of prior cesarean section were comparable between the 2 groups. The adenomyosis detection rate was significantly higher in the expert gynecologic sonologist group compared with radiologists (95 [56%] vs 29 [12%], p <.01). After controlling for patients' race, body mass index, prior cesarean sections, and presence of myomas using multivariable logistic regression, gynecologic expert sonologists were 7.8 times more likely to detect adenomyosis than radiologists (odds ratio = 7.84; 95% confidence interval, 4.58-13.44). Regardless of medical specialty, the presence of myomas significantly decreased the detection of adenomyosis compared with the absence of myomas (odds ratio = 0.23; 95% confidence interval, 0.13-0.39). CONCLUSION: The detection rate of adenomyosis was significantly higher when ultrasound was performed by expert gynecologic sonologists compared with radiologists. The presence of myomas significantly decreased detection rates regardless of specialty. Ultrasound evaluation for detecting adenomyosis should be preferentially performed by gynecologic expert sonologists.