TECHNOLOGY

Advances in the high resolution microscopes and digital imaging technologies have allowed us to visualize diffusible signaling cascades from the protein receptors in the cell membrane to the nucleus. As multi-omics biology evolves over time, building predictable DNA-RNA-protein expression, protein-protein interaction networks and thereby spatiotemporal dynamics of molecular events will help us to uncover differences on cell morphology and physiology between normal and disease states. Here we present an update on optical, fluorescence and electron transmitted microscopes and mass spectrometer imaging technologies and various ways we can apply them for biological discovery and diagnose of human diseases.

Due to its real-time, non-radiation based three-dimensional (3D) imaging capabilities, ultrasound (US) has been incorporated into various orthopedic procedures. However, imaging artifacts, low signal-to-noise ratio (SNR) and bone boundaries appearing several mm in thickness make the analysis of US data difficult. This paper provides a review about the state-of-the-art bone segmentation and enhancement methods developed for two-dimensional (2D) and 3D US data. First, an overview for the appearance of bone surface response in B-mode data is presented. Then, classification of the proposed techniques in terms of the image information being used is provided. Specifically, the focus is given on segmentation and enhancement of B-mode US data. The review is concluded by discussing future directions of research and additional challenges which need to be overcome in order to make this imaging modality more successful in orthopedics.

The transition of macrophages from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype is crucial for the progression of normal wound healing. Persistent M1 macrophages within the injury site may lead to an uncontrolled macrophage-mediated inflammatory response and ultimately a failure of the wound healing cascade, leading to chronic wounds. Mesenchymal stromal cells (MSCs) have been widely reported to promote M1 to M2 macrophage transition; however, it is unclear whether MSCs can drive this transition in the hypoxic environment typically observed in chronic wounds. Here we report on the effect of hypoxia (1% O${}_{\mathrm{\text{2}}})$ on MSCs’ ability to transition macrophages from the M1 to the M2 phenotype. While hypoxia had no effect on MSC secretion, it inhibited MSC-induced M1 to M2 macrophage transition, and suppressed macrophage expression and production of the anti-inflammatory mediator interleukin-10 (IL-10). These results suggest that hypoxic environments may impede the therapeutic effects of MSCs.

Neurocircuits in the human brain govern complex behavior and involve connections from many different neuronal subtypes from different brain regions. Recent advances in stem cell biology have enabled the derivation of patient-specific human neuronal cells of various subtypes for the study of neuronal function and disease pathology. Nevertheless, one persistent challenge using these human-derived neurons is the ability to reconstruct models of human brain circuitry. To overcome this obstacle, we have developed a compartmentalized microfluidic device, which allows for spatial separation of cell bodies of different human-derived neuronal subtypes (excitatory, inhibitory and dopaminergic) but is permissive to the spreading of projecting processes. Induced neurons (iNs) cultured in the device expressed pan-neuronal markers and subtype specific markers. Morphologically, we demonstrate defined synaptic contacts between selected neuronal subtypes by synapsin staining. Functionally, we show that excitatory neuronal stimulation evoked excitatory postsynaptic current responses in the neurons cultured in a separate chamber.

The anterior cruciate ligament (ACL) is the most commonly injured ligament in the knee, with more than 350,000 ACL injuries reported annually in the US. Current treatments include the use of autografts and allografts, which have a number of disadvantages. Previous attempts to use synthetic materials in ligament replacement have been unsuccessful due to their inability to replicate the long-term mechanical properties of the native ligament. The focus of this study was to develop twist-braid poly(L-lactic acid) (PLLA) scaffolds for ACL regeneration. Poly(ethylene glycol) diacrylate (PEGDA) was incorporated into the twist-braid scaffolds to evaluate its impact on their mechanical behavior. The twist-braid scaffolds were also compared with braided scaffolds. Scaffold mechanical properties were evaluated based on stress-relaxation, tensile and fatigue properties of the braided-only, twist-braid, and the twist-braid scaffolds with PEGDA. All the scaffolds exhibited properties comparable to the native human ACL with the twist-braid scaffolds displaying resistance to fatigue. Scaffolds were seeded with rat patellar tendon fibroblasts. Cell viability and the amount of protein released were studied over a course of 8 weeks. The scaffolds were stained with Picrosirius red after 8 weeks to show the deposition of extracellular matrix by the cells. The results from this study showed that the twist-braid scaffolds have properties most suitable for ligament regeneration.

The widespread bacterial resistance to a broad range of antibiotics necessitates rapid antibiotic susceptibility testing before effective treatment could start in the clinic. Among resistant bacteria, Staphylococcus aureus is one of the most important, and Methicillin-resistant (MRSA) strains are a common cause of life threatening infections. However, standard susceptibility testing for S. aureus is time consuming and thus the start of effective antibiotic treatment is often delayed. To circumvent the limitations of current susceptibility testing systems, we designed an assay that enables measurements of bacterial growth with higher spatial and temporal resolution than standard techniques. The assay consists of arrays of microwells that confine small number of bacteria in small spaces, where their growth is monitored with high precision. These devices enabled us to investigate the effect of different antibiotics on S. aureus growth. We measured the Minimal Inhibitory Concentration (MIC) in less than 3 hours. In addition to being significantly faster than the 48 hours needed for traditional microbiological methods, the assay is also capable of differentiating the specific effects of different antibiotic classes on S. aureus growth. Overall, this assay has the potential to become a rapid, sensitive, and robust tool for use in hospitals and laboratories to assess antibiotic sensitivity.